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Evaluation of image quality and radiation dose at prospective ECG-triggered axial 256-slice multi-detector CT in infants with congenital heart disease
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Huang, Mei-ping; Liang, Chang-hong; Zhao, Zhen-jun; Liu, Hui; Li, Jing-lei; Zhang, Jin-e; Cui, Yan-hai; Yang, Lin; Liu, Qi-shun [Guangdong Academy of Medical Sciences, Guangdong General Hospital, Department of Radiology, Guangzhou (China); Ivanc, Thomas B.; Vembar, Mani [Philips Healthcare, CT Clinical Science, Highland Heights, OH (United States)
There are a limited number of reports on the technical and clinical feasibility of prospective electrocardiogram (ECG)-gated multi-detector computed tomography (MDCT) in infants with congenital heart disease (CHD). To evaluate image quality and radiation dose at weight-based low-dose prospectively gated 256-slice MDCT angiography in infants with CHD. From November 2009 to February 2010, 64 consecutive infants with CHD referred for pre-operative or post-operative CT were included. All were scanned on a 256-slice MDCT system utilizing a low-dose protocol (80 kVp and 60-120 mAs depending on weight: 60 mAs for {<=}3 kg, 80 mAs for 3.1-6 kg, 100 mAs for 6.1-10 kg, 120 mAs for 10.1-15 kg). No serious adverse events were recorded. A total of 174 cardiac deformities, confirmed by surgery or heart catheterization, were studied. The sensitivity of MDCT for cardiac deformities was 97.1%; specificity, 99.4%; accuracy, 95.9%. The mean heart rate during scan was 136.7 {+-} 14.9/min (range, 91-160) with a corresponding heart rate variability of 2.8 {+-} 2.2/min (range, 0-8). Mean scan length was 115.3 {+-} 11.7 mm (range, 93.6-143.3). Mean volume CT dose index, mean dose-length product and effective dose were 2.1 {+-} 0.4 mGy (range, 1.5-2.8), 24.7 {+-} 5.9 mGy.cm (range, 14.7-35.8) and 1.6 {+-} 0.3 mSv (range, 1.1-2.5), respectively. Diagnostic-quality images were achieved in all cases. Satisfactory diagnostic quality for visualization of all/proximal/distal coronary artery segments was achieved in 88.4/98.8/80.0% of the scans. Low-dose prospectively gated axial 256-slice CT angiography is a valuable tool in the routine clinical evaluation of infants with CHD, providing a comprehensive three-dimensional evaluation of the cardiac anatomy, including the coronary arteries. (orig.)
Prospective ECG-triggered axial CT at 140-kV tube voltage improves coronary in-stent restenosis visibility at a lower radiation dose compared with conventional retrospective ECG-gated helical CT
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Horiguchi, Jun; Fujioka, Chikako; Kiguchi, Masao; Kohno, Shingo [Hiroshima University Hospital, Department of Clinical Radiology, Hiroshima (Japan); Yamamoto, Hideya; Kitagawa, Toshiro [Hiroshima University, Department of Molecular and Internal Medicine, Division of Clinical Medical Science, Programs for Applied Biomedicine, Graduate School of Biomedical Sciences, Hiroshima (Japan); Ito, Katsuhide [Hiroshima University, Department of Radiology, Division of Medical Intelligence and Informatics, Programs for Applied Biomedicine, Graduate School of Biomedical Sciences, Hiroshima (Japan)
The purpose of this study was to compare coronary 64-slice CT angiography (CTA) protocols, specifically prospective electrocardiograph (ECG)-triggered and retrospective ECG-gated CT acquisition performed using a tube voltage of 140 kV and 120 kV, regarding intracoronary stent imaging. Coronary artery stents (n=12) with artificial in-stent restenosis (50% luminal reduction, 40 HU) on a cardiac phantom were examined by CT at heart rates of 50-75 beats per minute (bpm). The subjective visibility of in-stent restenosis was evaluated with a three-point scale (1 clearly visible, 2 visible, and 3 not visible), and artificial lumen narrowing [(inner stent diameter - measured lumen diameter)/inner stent diameter], lumen attenuation increase ratio [(in-stent attenuation - coronary lumen attenuation)/coronary lumen attenuation], and signal-to-noise ratio of in-stent lumen were determined. The effective dose was estimated. The artificial lumen narrowing (mean 43%), the increase of lumen attenuation (mean 46%), and signal-to-noise ratio (mean 7.8) were not different between CT acquisitions (p=0.12-0.91). However, the visibility scores of in-stent restenosis were different (p<0.05) between ECG-gated CTA techniques: (a) 140-kV prospective (effective dose 4.6 mSv), 1.6; (b) 120-kV prospective (3.3 mSv), 1.8; (c) 140-kV retrospective (16.4-18.8 mSv), 1.9; and (d) 120-kV retrospective (11.0-13.4 mSv), 1.9. Thus, 140-kV prospective ECG-triggered CTA improves coronary in-stent restenosis visibility at a lower radiation dose compared with retrospective ECG-gated CTA. (orig.)
Cerebral angiography with prospective ECG triggering preliminary study of dual-source CT
International Nuclear Information System (INIS)
Xue Yuejun; Qian Nong; Shao Yanhui; Pan Changjie; Rong Weiliang; Xu Yiqun
Objective: To study the image quality and radiation dose in dual-source CT cerebral angiography with prospective ECG-triggered sequence mode (step-and-shoot, SAS). Methods: A total of forty-three patients with clinically suspected cerebral vascular disease underwent cerebral CT angiography with prospective ECG-triggering (step-and-shoot, SAS). Data acquisition was at 60% R-R interval of the ECG presentation mode. The post-processing included maximum intensity projection (MIP), multiplanar reformation (MPR) and volume rendering (VR). The CTA image quality, radiation dose and rates of excellent images were evaluated. Results: The CTA image quality score was 4.72 ± 0.50 and 97.7% (42/43) patients had excellent CTA images. The average effective dose of SAS-CTA was (0.22 ± 0.01)mSv, which was lower by 76.31% than that of DE-CTA. Conclusions: Prospective ECG-triggering sequence could be used in cerebral angiography with a significant reduction in radiation dose and diagnostic image quality. (authors)
Impact of heart rate and rhythm on radiation exposure in prospectively ECG triggered computed tomography
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Luecke, Christian, E-mail: email@example.com [University of Leipzig – Heart Center, Department of Diagnostic and Interventional Radiology, Strümpellstrasse 39, D-04289, Leipzig (Germany); Andres, Claudia; Foldyna, Borek [University of Leipzig – Heart Center, Department of Diagnostic and Interventional Radiology, Strümpellstrasse 39, D-04289, Leipzig (Germany); Nagel, Hans Dieter [Wissenschaft and Technik für die Radiologie, Buchhholz i.d.N (Germany); Hoffmann, Janine; Grothoff, Matthias; Nitzsche, Stefan; Gutberlet, Matthias; Lehmkuhl, Lukas [University of Leipzig – Heart Center, Department of Diagnostic and Interventional Radiology, Strümpellstrasse 39, D-04289, Leipzig (Germany)
Purpose: To evaluate the influence of different heart rates and arrhythmias on scanner performance, image acquisition and applied radiation exposure in prospectively ECG triggered computed tomography (pCT). Materials and methods: An ECG simulator (EKG Phantom 320, Müller and Sebastiani Elektronik GmbH, Munich, Germany) was used to generate different heart rhythms and arrhythmias: sinus rhythm (SR) at 45, 60, 75, 90 and 120/min, supraventricular arrhythmias (e.g. sinus arrhythmia, atrial fibrillation) and ventricular arrhythmias (e.g. ventricular extrasystoles), pacemaker-ECGs, ST-changes and technical artifacts. The analysis of the image acquisition process was performed on a 64-row multidetector CT (Brilliance, Philips Medical Systems, Cleveland, USA). A prospectively triggered scan protocol as used for routine was applied (120 kV; 150 mA s; 0.4 s rotation and exposure time per scan; image acquisition predominantly in end-diastole at 75% R-R-interval, in arrythmias with a mean heart rate above 80/min in systole at 45% of the R-R-interval; FOV 25 cm). The mean dose length product (DLP) and its percentage increase from baseline (SR at 60/min) were determined. Result: Radiation exposure can increase significantly when the heart rhythm deviates from sinus rhythm. ECG-changes leading to a significant DLP increase (p < 0.05) were bifocal pacemaker (61%), pacemaker dysfunction (22%), SVES (20%), ventricular salvo (20%), and atrial fibrillation (14%). Significantly (p < 0.05) prolonged scan time (>8 s) could be observed in bifocal pacemaker (12.8 s), pacemaker dysfunction (10.7 s), atrial fibrillation (10.3 s) and sinus arrhythmia (9.3 s). Conclusion: In prospectively ECG triggered CT, heart rate and rhythm can provoke different types of scanner performance, which can significantly alter radiation exposure and scan time. These results might have an important implication for indication, informed consent and contrast agent injection protocols.
Impact of heart rate and rhythm on radiation exposure in prospectively ECG triggered computed tomography
International Nuclear Information System (INIS)
Luecke, Christian; Andres, Claudia; Foldyna, Borek; Nagel, Hans Dieter; Hoffmann, Janine; Grothoff, Matthias; Nitzsche, Stefan; Gutberlet, Matthias; Lehmkuhl, Lukas
Purpose: To evaluate the influence of different heart rates and arrhythmias on scanner performance, image acquisition and applied radiation exposure in prospectively ECG triggered computed tomography (pCT). Materials and methods: An ECG simulator (EKG Phantom 320, Müller and Sebastiani Elektronik GmbH, Munich, Germany) was used to generate different heart rhythms and arrhythmias: sinus rhythm (SR) at 45, 60, 75, 90 and 120/min, supraventricular arrhythmias (e.g. sinus arrhythmia, atrial fibrillation) and ventricular arrhythmias (e.g. ventricular extrasystoles), pacemaker-ECGs, ST-changes and technical artifacts. The analysis of the image acquisition process was performed on a 64-row multidetector CT (Brilliance, Philips Medical Systems, Cleveland, USA). A prospectively triggered scan protocol as used for routine was applied (120 kV; 150 mA s; 0.4 s rotation and exposure time per scan; image acquisition predominantly in end-diastole at 75% R-R-interval, in arrythmias with a mean heart rate above 80/min in systole at 45% of the R-R-interval; FOV 25 cm). The mean dose length product (DLP) and its percentage increase from baseline (SR at 60/min) were determined. Result: Radiation exposure can increase significantly when the heart rhythm deviates from sinus rhythm. ECG-changes leading to a significant DLP increase (p 8 s) could be observed in bifocal pacemaker (12.8 s), pacemaker dysfunction (10.7 s), atrial fibrillation (10.3 s) and sinus arrhythmia (9.3 s). Conclusion: In prospectively ECG triggered CT, heart rate and rhythm can provoke different types of scanner performance, which can significantly alter radiation exposure and scan time. These results might have an important implication for indication, informed consent and contrast agent injection protocols
Double prospectively ECG-triggered high-pitch spiral acquisition for CT coronary angiography: Initial experience
International Nuclear Information System (INIS)
Wang, Q.; Qin, J.; He, B.; Zhou, Y.; Yang, J.-J.; Hou, X.-L.; Yang, X.-B.; Chen, J.-H.; Chen, Y.-D.
Aim: To evaluate the feasibility of double prospectively electrocardiogram (ECG)-triggered high-pitch spiral acquisition mode (double high-pitch mode) for coronary computed tomography angiography (CTCA). Materials and methods: One hundred and forty-nine consecutive patients [40 women, 109 men; mean age 58.2 ± 9.2 years; sinus rhythm ≤70 beats/min (bpm) after pre-medication, body weight ≤100 kg] were enrolled for CTCA examinations using a dual-source CT system with 2 × 128 × 0.6 mm collimation, 0.28 s rotation time, and a pitch of 3.4. Double high-pitch mode was prospectively triggered first at 60% and later at 30% of the R–R interval within two cardiac cycles. Image quality was evaluated using a four-point scale (1 = excellent, 4 = non-assessable). Results: From 2085 coronary artery segments, 86.4% (1802/2085) were rated as having a score of 1, 12.3% (257/2085) as score of 2, 1.2% (26/2085) as score of 3, and none were rated as "non-assessable". The average image quality score was 1.15 ± 0.26 on a per-segment basis. The effective dose was calculated by multiplying the coefficient factor of 0.028 by the dose–length product (DLP); the mean effective dose was 3.5 ± 0.8 mSv (range 1.7–7.6 mSv). The total dosage of contrast medium was 78.7 ± 2.9 ml. Conclusion: Double prospectively ECG-triggered high-pitch spiral acquisition mode provides good image quality with an average effective dose of less than 5 mSv in patients with a heart rate ≤70 bpm
Coronary CT angiography using prospective ECG triggering. High diagnostic accuracy with low radiation dose
International Nuclear Information System (INIS)
Arnoldi, E.; Ramos-Duran, L.; Abro, J.A.; Costello, P.; Zwerner, P.L.; Schoepf, U.J.; Nikolaou, K.; Reiser, M.F.
The purpose of this study was to evaluate the diagnostic performance of coronary CT angiography (coronary CTA) using prospective ECG triggering (PT) for the detection of significant coronary artery stenosis compared to invasive coronary angiography (ICA). A total of 20 patients underwent coronary CTA with PT using a 128-slice CT scanner (Definition trademark AS+, Siemens) and ICA. All coronary CTA studies were evaluated for significant coronary artery stenoses (≥50% luminal narrowing) by 2 observers in consensus using the AHA-15-segment model. Findings in CTA were compared to those in ICA. Coronary CTA using PT had 88% sensitivity in comparison to 100% with ICA, 95% to 88% specificity, 80% to 92% positive predictive value and 97% to 100% negative predictive value for diagnosing significant coronary artery stenosis on per segment per patient analysis, respectively. Mean effective radiation dose-equivalent of CTA was 2.6±1 mSv. Coronary CTA using PT enables non-invasive diagnosis of significant coronary artery stenosis with high diagnostic accuracy in comparison to ICA and is associated with comparably low radiation exposure. (orig.) [de
Imaging of pulmonary vein anatomy using low-dose prospective ECG-triggered dual-source computed tomography
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Blanke, Philipp; Baumann, Tobias; Langer, Mathias; Pache, Gregor [University Hospital Freiburg, Department of Diagnostic Radiology, Freiburg (Germany)
To prospectively investigate the feasibility, image quality and radiation dose estimates for computed tomography angiography (CTA) of the pulmonary veins and left atrium using prospective electrocardiography (ECG)-triggered sequential dual-source (DS) data acquisition at end-systole in patients with paroxysmal atrial fibrillation undergoing radiofrequency ablation. Thirty-five patients (mean age 66.2 {+-} 12.6 years) with paroxysmal atrial fibrillation underwent prospective ECG-triggered sequential DS-CTA with tube current (250 mAs/rotation) centred 250 ms past the R-peak. Tube voltage was adjusted to the BMI (<25 kg/m{sup 2}: 100 kV, >25 kg/m{sup 2}: 120 kV). Presence of motion or stair-step artefacts was assessed. Effective radiation dose was calculated from the dose-length product. All data sets could be integrated into the electroanatomical mapping system. Twenty-two patients (63%) were in sinus rhythm (mean heart rate 69.2 {+-} 11.1 bpm, variability 1.0 {+-} 1.7 bpm) and 13 (37%) showed an ECG pattern of atrial fibrillation (mean heart rate 84.8 {+-} 16.6 bpm, variability 17.9 {+-} 7.5 bpm). Minor step artefacts were observed in three patients (23%) with atrial fibrillation. Mean estimated effective dose was 1.1 {+-} 0.3 and 3.0 {+-} 0.5 mSv for 100 and 120 kV respectively. Imaging of pulmonary vein anatomy is feasible using prospective ECG-triggered sequential data acquisition at end-systole regardless of heart rate or rhythm at the benefit of low radiation dose. (orig.)
Imaging of pulmonary vein anatomy using low-dose prospective ECG-triggered dual-source computed tomography
International Nuclear Information System (INIS)
Blanke, Philipp; Baumann, Tobias; Langer, Mathias; Pache, Gregor
To prospectively investigate the feasibility, image quality and radiation dose estimates for computed tomography angiography (CTA) of the pulmonary veins and left atrium using prospective electrocardiography (ECG)-triggered sequential dual-source (DS) data acquisition at end-systole in patients with paroxysmal atrial fibrillation undergoing radiofrequency ablation. Thirty-five patients (mean age 66.2 ± 12.6 years) with paroxysmal atrial fibrillation underwent prospective ECG-triggered sequential DS-CTA with tube current (250 mAs/rotation) centred 250 ms past the R-peak. Tube voltage was adjusted to the BMI ( 2 : 100 kV, >25 kg/m 2 : 120 kV). Presence of motion or stair-step artefacts was assessed. Effective radiation dose was calculated from the dose-length product. All data sets could be integrated into the electroanatomical mapping system. Twenty-two patients (63%) were in sinus rhythm (mean heart rate 69.2 ± 11.1 bpm, variability 1.0 ± 1.7 bpm) and 13 (37%) showed an ECG pattern of atrial fibrillation (mean heart rate 84.8 ± 16.6 bpm, variability 17.9 ± 7.5 bpm). Minor step artefacts were observed in three patients (23%) with atrial fibrillation. Mean estimated effective dose was 1.1 ± 0.3 and 3.0 ± 0.5 mSv for 100 and 120 kV respectively. Imaging of pulmonary vein anatomy is feasible using prospective ECG-triggered sequential data acquisition at end-systole regardless of heart rate or rhythm at the benefit of low radiation dose. (orig.)
Calcium scoring with prospectively ECG-triggered CT: Using overlapping datasets generated with MPR decreases inter-scan variability
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Rutten, A.; Isgum, I.; Prokop, M.
Objective: To examine the feasibility of reducing the inter-scan variability of prospectively ECG-triggered calcium-scoring scans by using overlapping 3-mm datasets generated from multiplanar reformation (MPR) instead of non-overlapping 3-mm or 1.5-mm datasets. Patients and methods: Seventy-five women (59-79 years old) underwent two sequential prospectively ECG-triggered calcium-scoring scans with 16 mm x 1.5 mm collimation in one session. Between the two scans patients got off and on the table. We performed calcium scoring (Agatston and mass scores) on the following datasets: contiguous 3-mm sections reconstructed from the raw data (A), contiguous 3-mm sections from MPR (B), overlapping 3-mm sections from MPR (C) and contiguous 1.5-mm sections from the raw data (D). To determine the feasibility of the MPR approach, we compared MPR (B) with direct raw data reconstruction (A). Inter-scan variability was calculated for each type of dataset (A-D). Results: Calcium scores ranged from 0 to 1455 (Agatston) and 0 to 279 mg (mass) for overlapping 3-mm sections (C). Calcium scores (both Agatston and mass) were nearly identical for MPR (B) and raw data approaches (A), with inter-quartile ranges of 0-1% for inter-scan variability. Median inter-scan variability with contiguous 3-mm sections (B) was 13% (Agatston) and 11% (mass). Median variability was reduced to 10% (Agatston and mass) with contiguous 1.5-mm sections (D) and to 8% (Agatston) and 7% (mass) with overlapping 3-mm MPR (A). Conclusion: Calcium scoring on MPR yields nearly identical results to calcium scoring on images directly reconstructed from raw data. Overlapping MPR from prospectively ECG-triggered scans improve inter-scan variability of calcium scoring without increasing patient radiation dose.
Feasibility and diagnostic accuracy of a low radiation exposure protocol for prospective ECG-triggering coronary MDCT angiography
International Nuclear Information System (INIS)
Pontone, G.; Andreini, D.; Bartorelli, A.L.; Bertella, E.; Mushtaq, S.; Foti, C.; Formenti, A.; Chiappa, L.; Annoni, A.; Cortinovis, S.; Baggiano, A.; Conte, E.; Bovis, F.; Veglia, F.; Ballerini, G.; Agostoni, P.; Fiorentini, C.; Pepi, M.
Aim: To compare the feasibility, accuracy, and effective radiation dose (ED) of multidetector computed tomography (MDCT) in the detection of coronary artery disease using a combined ED-saving strategy including prospective electrocardiogram (ECG) triggering with a short x-ray window and a body mass index (BMI)-adapted imaging protocol using adaptive statistical iterative reconstruction (ASIR; group 1), in comparison with a prospective ECG triggering strategy alone (group 2). Materials and methods: One hundred and seventy patients scheduled for invasive coronary angiography (ICA) were evaluated. Fourteen patients were not eligible for MDCT. The remaining 156 patients were randomized to group 1 (78 patients) and group 2 (78 patients). Eight and 11 patients in groups 1 and 2, respectively, were excluded after randomization because the patients' heart rates were >65 beats/min. MDCT images were assessed for feasibility, signal-to-noise ration (SNR), and contrast-to-noise ratio (CNR), accuracy in detection of coronary stenoses >50% versus ICA and for ED. Results: The feasibility, SNR, CNR, accuracy in a segment-based and patient-based model were similar in both groups (97 versus 95%, 14.5 ± 3.9 versus 14.2 ± 4.1, 16 ± 4.6 versus 16.5 ± 4.4, 95 versus 94% and 97 versus 99%, respectively). The ED in group 1 was 72% lower than in group 2 (2.1 ± 1.2 versus 7.5 ± 1.8 mSv, respectively; p < 0.01). Conclusions: The use of a multi-parametric ED saving protocol results in a significant reduction in ED without a negative impact on accuracy.
Feasibility and diagnostic accuracy of a low radiation exposure protocol for prospective ECG-triggering coronary MDCT angiography
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Pontone, G., E-mail: firstname.lastname@example.com [Centro Cardiologico Monzino, IRCCS, Milan (Italy); Andreini, D. [Centro Cardiologico Monzino, IRCCS, Milan (Italy); Bartorelli, A.L. [Centro Cardiologico Monzino, IRCCS, Milan (Italy); Department of Cardiovascular Sciences, University of Milan, Milan (Italy); Bertella, E.; Mushtaq, S.; Foti, C.; Formenti, A.; Chiappa, L.; Annoni, A.; Cortinovis, S.; Baggiano, A.; Conte, E.; Bovis, F.; Veglia, F.; Ballerini, G. [Centro Cardiologico Monzino, IRCCS, Milan (Italy); Agostoni, P.; Fiorentini, C. [Centro Cardiologico Monzino, IRCCS, Milan (Italy); Department of Cardiovascular Sciences, University of Milan, Milan (Italy); Pepi, M. [Centro Cardiologico Monzino, IRCCS, Milan (Italy)
Aim: To compare the feasibility, accuracy, and effective radiation dose (ED) of multidetector computed tomography (MDCT) in the detection of coronary artery disease using a combined ED-saving strategy including prospective electrocardiogram (ECG) triggering with a short x-ray window and a body mass index (BMI)-adapted imaging protocol using adaptive statistical iterative reconstruction (ASIR; group 1), in comparison with a prospective ECG triggering strategy alone (group 2). Materials and methods: One hundred and seventy patients scheduled for invasive coronary angiography (ICA) were evaluated. Fourteen patients were not eligible for MDCT. The remaining 156 patients were randomized to group 1 (78 patients) and group 2 (78 patients). Eight and 11 patients in groups 1 and 2, respectively, were excluded after randomization because the patients' heart rates were >65 beats/min. MDCT images were assessed for feasibility, signal-to-noise ration (SNR), and contrast-to-noise ratio (CNR), accuracy in detection of coronary stenoses >50% versus ICA and for ED. Results: The feasibility, SNR, CNR, accuracy in a segment-based and patient-based model were similar in both groups (97 versus 95%, 14.5 {+-} 3.9 versus 14.2 {+-} 4.1, 16 {+-} 4.6 versus 16.5 {+-} 4.4, 95 versus 94% and 97 versus 99%, respectively). The ED in group 1 was 72% lower than in group 2 (2.1 {+-} 1.2 versus 7.5 {+-} 1.8 mSv, respectively; p < 0.01). Conclusions: The use of a multi-parametric ED saving protocol results in a significant reduction in ED without a negative impact on accuracy.
Diagnostic accuracy of sub-mSv prospective ECG-triggering cardiac CT in young infant with complex congenital heart disease.
Gao, Wei; Zhong, Yu Min; Sun, Ai Min; Wang, Qian; Ouyang, Rong Zhen; Hu, Li Wei; Qiu, Han Sheng; Wang, Shi Yu; Li, Jian Ying
To explore the clinical value and evaluate the diagnostic accuracy of sub-mSv low-dose prospective ECG-triggering cardiac CT (CCT) in young infants with complex congenital heart disease (CHD). A total of 102 consecutive infant patients (53 boys and 49 girls with mean age of 2.9 ± 2.4 m and weight less than 5 kg) with complex CHD were prospectively enrolled. Scans were performed on a 64-slice high definition CT scanner with low dose prospective ECG-triggering mode and reconstructed with 80 % adaptive statistical iterative reconstruction algorithm. All studies were performed during free breathing with sedation. The subjective image quality was evaluated by 5-point grading scale and interobserver variability was calculated. The objective image noise (standard deviation, SD) and contrast to noise ratio (CNR) was calculated. The effective radiation dose from the prospective ECG-triggering mode was recorded and compared with the virtual conventional retrospective ECG-gating mode. The detection rate for the origin of coronary artery was calculated. All patients also underwent echocardiography before CCT examination. 81 patients had surgery and their preoperative CCT and echocardiography findings were compared with the surgical results and sensitivity, specificity, positive and negative predictive values and accuracy were calculated for separate cardiovascular anomalies. Heart rates were 70-161 beats per minute (bpm) with mean value of 129.19 ± 14.52 bpm. The effective dose of 0.53 ± 0.15 mSv in the prospective ECG-triggering cardiac CT was lower than the calculated value in a conventional retrospective ECG-gating mode (2.00 ± 0.35 mSv) (p ECG-triggering CCT with sub-mSv effective dose provides excellent imaging quality and high diagnostic accuracy for young infants with complex CHD.
Dose reduction using prospective electrocardiograph-triggered axial coronary scan on the 64-slice spiral CT
International Nuclear Information System (INIS)
Wang Yanyan; Wu Guogeng; Zhou Cheng; Gao Jianhua; Jiao Sheng; Cao Huizhi
Objective: To compare radiation dose and image quality between prospective electrocardiograph (ECG)-triggered axial scan and retrospective ECG-gated helical scan in coronary 64-slice CT angiography (CTA). Methods: Seventy-seven consecutive patients [group A. Average body mass index (BMI): 24.6, heart rate 0.05). Conclusion: Prospective ECG-triggered axial scan in 64-slice coronary CTA can significantly reduce radiation exposure and the image quality can fulfill clinical diagnostic needs. (authors)
Feasibility of prospectively ECG-triggered high-pitch coronary CT angiography with 30 mL iodinated contrast agent at 70 kVp: initial experience
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Zhang, Long Jiang; Qi, Li; Tang, Chun Xiang; Zhou, Chang Sheng; Ji, Xue Man; Lu, Guang Ming [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Wang, Jing [Medical School of Nanjing University, Department of Cardiology, Jinling Hospital, Nanjing, Jiangsu (China); Spearman, James V.; De Cecco, Carlo Nicola; Meinel, Felix G. [Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States); Schoepf, U.J. [Medical School of Nanjing University, Department of Medical Imaging, Jinling Hospital, Nanjing, Jiangsu (China); Medical University of South Carolina, Department of Radiology and Radiological Science, Charleston, SC (United States)
To evaluate the feasibility, image quality and radiation dose of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) with 30 mL contrast agent at 70 kVp. Fifty-eight patients with suspected coronary artery disease, a body mass index (BMI) of less than 25 kg/m{sup 2}, sinus rhythm and a heart rate (HR) of less than 70 beats per minute (bpm) were prospectively enrolled in this study. Thirty mL of 370 mg I/mL iodinated contrast agent was administrated at a flow rate of 5 mL/s. All patients underwent prospectively ECG-triggered high-pitch CCTA on a second-generation dual-source CT system at 70 kVp using automated tube current modulation. Fifty-six patients (96.6 %) had diagnostic CCTA images and two patients (3.4 %) had one vessel with poor image quality each rated as non-diagnostic. No significant effects of HR, HR variability and BMI on CCTA image quality were observed (all P > 0.05). Effective dose was 0.17 ± 0.02 mSv and the size-specific dose estimate was 1.03 ± 0.13 mGy. Prospectively ECG-triggered high-pitch CCTA at 70 kVp with 30 mL of contrast agent can provide diagnostic image quality at a radiation dose of less than 0.2 mSv in patients with a BMI of less than 25 kg/m{sup 2} and an HR of less than 70 bpm. (orig.)
Prospectively ECG-triggered sequential dual-source coronary CT angiography in patients with atrial fibrillation: comparison with retrospectively ECG-gated helical CT
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Xu, Lei; Yang, Lin; Zhang, Zhaoqi [Capital Medical University, Department of Radiology, Beijing Anzhen Hospital, Beijing (China); Wang, Yining; Jin, Zhengyu [Chinese Academy of Medical Sciences, Department of Radiology, Peking Union Medical College Hospital, Beijing (China); Zhang, Longjiang; Lu, Guangming [Nanjing University, Department of Medical Imaging, Jinling Hospital, Clinical School of Medical College, Nanjing, Jiangsu (China)
To investigate the feasibility of applying prospectively ECG-triggered sequential coronary CT angiography (CCTA) to patients with atrial fibrillation (AF) and evaluate the image quality and radiation dose compared with a retrospectively ECG-gated helical protocol. 100 patients with persistent AF were enrolled. Fifty patients were randomly assigned to a prospective protocol and the other patients to a retrospective protocol using a second-generation dual-source CT (DS-CT). Image quality was evaluated using a four-point grading scale (1 = excellent, 2 = good, 3 = moderate, 4 = poor) by two reviewers on a per-segment basis. The coronary artery segments were considered non-diagnostic with a quality score of 4. The radiation dose was evaluated. Diagnostic segment rate in the prospective group was 99.4 % (642/646 segments), while that in the retrospective group was 96.5 % (604/626 segments) (P < 0.001). Effective dose was 4.29 {+-} 1.86 and 11.95 {+-} 5.34 mSv for each of the two protocols (P < 0.001), which was a 64 % reduction in the radiation dose for prospective sequential imaging compared with retrospective helical imaging. In AF patients, prospectively ECG-triggered sequential CCTA is feasible using second-generation DS-CT and can decrease >60 % radiation exposure compared with retrospectively ECG-gated helical imaging while improving diagnostic image quality. (orig.)
The optimal dose reduction level using iterative reconstruction with prospective ECG-triggered coronary CTA using 256-slice MDCT
International Nuclear Information System (INIS)
Hou, Yang; Xu, Shu; Guo, Wenli; Vembar, Mani; Guo, Qiyong
Aim: To assess the image quality (IQ) of an iterative reconstruction (IR) technique (iDose 4 ) from prospective electrocardiography (ECG)-triggered coronary computed tomography angiography (coronary CTA) on a 256-slice multi-detector CT (MDCT) scanner and determine the optimal dose reduction using IR that can provide IQ comparable to filtered back projection (FBP). Method and materials: 110 consecutive patients (69 men, 41 women; age: 54 ± 10 years) underwent coronary CTA on a 256-slice MDCT (Brilliance iCT, Philips Healthcare). The control group (Group A, n = 21) were scanned using the conventional tube output (120 kVp, 210 mAs) and reconstructed using FBP. The other 4 groups were scanned with the same kVp but successively reduced tube output as follows: B[n = 15]: 125 mAs; C[n = 22]: 105 mAs; D[n = 36]: 84 mAs: E[n = 16]: 65 mAs) and reconstructed using IR levels of L3 (Group B), L4 (Group C) and L5 (Groups D and E), to compensate for the noise increase. All images were reconstructed using the same kernel (XCB). Two radiologists graded IQ in a blinded fashion on a 4-point scale (4 – excellent, 3 – good, 2 – fair and 1 – poor). Quantitative measurements of CT values, image noise and contrast-to-noise (CNR) were measured in each group. A receiver-operating characteristic (ROC) analysis was performed to determine a radiation reduction threshold up to which excellent IQ was maintained. Results: There were no significant differences in objective noise, SNR and CNR values among Groups A, B, C, D, and E (P = 0.14, 0.09, 0.17, respectively). There were no significant differences in the scores of the subjective IQ between Group A, and Groups B, C, D, E (P = 0.23–0.97). Significant differences in image sharpness and study acceptability were observed between groups A and E (P < 0.05). Using the criterion of excellent IQ (score 4), the ROC curve of dose levels and IQ acceptability established a reduction of 60% of tube output (Group D) as optimum cutoff point (AUC
Prospective ECG triggering reduces prosthetic heart valve-induced artefacts compared with retrospective ECG gating on 256-slice CT
Symersky, P.; Habets, J.; Westers, P.; Mol, de B.A.J.M.; Prokop, M.; Budde, R.P.J.
Objectives Multidetector computed tomography (MDCT) has diagnostic value for the evaluation of prosthetic heart valve (PHV) dysfunction but it is hampered by artefacts. We hypothesised that image acquisition using prospective triggering instead of retrospective gating would reduce artefacts related
Image quality, radiation dose, and diagnostic accuracy of prospectively ECG-triggered high-pitch coronary CT angiography at 70 kVp in a clinical setting: comparison with invasive coronary angiography
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Zhang, Long Jiang; Qi, Li; Zhou, Chang Sheng; Zhao, Yan E.; Li, Xie; Lu, Guang Ming [Jinling Hospital, Medical School of Nanjing University, Department of Medical Imaging, Nanjing, Jiangsu (China); Wang, Yining; Cao, Jian; Jin, Zhengyu [Peking Union Medical College Hospital, Department of Radiology, Beijing (China); Schoepf, U.J. [Jinling Hospital, Medical School of Nanjing University, Department of Medical Imaging, Nanjing, Jiangsu (China); Medical University of South Carolina, Division of Cardiovascular Imaging, Charleston, SC (United States); Meinel, Felix G. [Medical University of South Carolina, Division of Cardiovascular Imaging, Charleston, SC (United States); Ludwig-Maximilians-University Hospital, Institute for Clinical Radiology, Munich (Germany); Bayer, Richard R. [Medical University of South Carolina, Division of Cardiovascular Imaging, Charleston, SC (United States); Gong, Jian Bin [Jinling Hospital, Medical School of Nanjing University, Department of Cardiology, Nanjing, Jiangsu (China)
To investigate image quality, radiation dose, and diagnostic performance of prospectively ECG-triggered high-pitch coronary CT angiography (CCTA) at 70 kVp compared to invasive coronary angiography (ICA) as reference standard. Forty-three patients underwent prospectively ECG-triggered high-pitch CCTA at 70 kVp using 30 cc (11 g iodine) contrast medium and ICA. Subjective and objective image quality was evaluated for each CCTA study. CCTA performance for diagnosing ≥50 % stenosis was assessed. Results were stratified according to heart rate (HR), body mass index (BMI), Agatston score, and image quality. At CCTA, 94.3 % (500/530) of coronary segments were of diagnostic quality. Using ICA as reference standard, sensitivity and accuracy were 100 % and 93.0 % on a per-patient basis. Per-vessel and per-segment performances were 92.2 % and 89.5 %; 79.5 % and 88.3 %, respectively. No differences were found in diagnostic accuracy between different HR, BMI, and calcification subgroups (all P > 0.05) on a per-patient basis. However, low image quality reduced diagnostic accuracy on a per-patient, per-vessel and per-segment basis (all P < 0.05). The mean effective radiation dose was 0.2 ± 0.0 mSv. Our presented protocol results in an effective radiation dose of 0.2 mSv and high diagnostic accuracy for stenosis detection in a selected, non-obese population. (orig.)
Prospective ECG triggering versus low-dose retrospective ECG-gated 128-channel CT coronary angiography: comparison of image quality and radiation dose
International Nuclear Information System (INIS)
Feng, Q.; Yin, Y.; Hua, X.; Zhu, R.; Hua, J.; Xu, J.
Aim: To evaluate image quality and radiation dose for 128-detector prospective electrocardiogram (ECG)-gated computed tomography coronary angiography (CTCA) compared with a low-dose retrospective ECG-gated imaging protocol. Materials and methods: Thirty-one and 47 patients suspected of having coronary artery disease were enrolled into groups examined using prospective and low-dose retrospective ECG-gated CT protocols respectively. All examinations were performed on a 128-detector CT system (Definition AS, Siemens Healthcare, Forchheim, Germany). Prospective CTCA was performed using following parameters: tube voltage 100 kV; tube current 205 mAs; centre of acquisition window 70% of the RR interval. The tube current for low-dose retrospective ECG-gated CTCA was full dose during 40-70% of the RR interval and partial dose for the rest of RR interval. The pitch varied between 0.2 and 0.5 depending on heart rate and patient size. Image quality of coronary arteries was evaluated using a four-point grading scale. The signal-to-noise ratios (SNRs) of enhanced arteries and myocardium were also measured, corresponding contrast-to-noise ratios (CNRs) were calculated, and the radiation doses received were recorded. Results: There was a significant difference in the image quality scores between the retrospective and prospective gating protocols (Chi-square = 15.331, p = 0.009). There was no significant difference between the SNRs of the contrasted artery and myocardium in these two groups, but the CNRs were increased in the prospective group. The mean radiation dose of prospective gating group was 2.71 ± 0.67 mSv (range, 1.67-3.59 mSv), which was significantly lower than that of the retrospective group (p < 0.001). Conclusion: Prospective CT angiography can achieve lower radiation dose than that of low-dose retrospective CT angiography, with preserved image quality.
Prospective ECG triggering versus low-dose retrospective ECG-gated 128-channel CT coronary angiography: comparison of image quality and radiation dose
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Feng, Q.; Yin, Y.; Hua, X.; Zhu, R.; Hua, J. [Department of Radiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai (China); Xu, J., E-mail: email@example.com [Department of Radiology, Renji Hospital, Shanghai Jiaotong University School of Medicine, Shanghai (China)
Aim: To evaluate image quality and radiation dose for 128-detector prospective electrocardiogram (ECG)-gated computed tomography coronary angiography (CTCA) compared with a low-dose retrospective ECG-gated imaging protocol. Materials and methods: Thirty-one and 47 patients suspected of having coronary artery disease were enrolled into groups examined using prospective and low-dose retrospective ECG-gated CT protocols respectively. All examinations were performed on a 128-detector CT system (Definition AS, Siemens Healthcare, Forchheim, Germany). Prospective CTCA was performed using following parameters: tube voltage 100 kV; tube current 205 mAs; centre of acquisition window 70% of the RR interval. The tube current for low-dose retrospective ECG-gated CTCA was full dose during 40-70% of the RR interval and partial dose for the rest of RR interval. The pitch varied between 0.2 and 0.5 depending on heart rate and patient size. Image quality of coronary arteries was evaluated using a four-point grading scale. The signal-to-noise ratios (SNRs) of enhanced arteries and myocardium were also measured, corresponding contrast-to-noise ratios (CNRs) were calculated, and the radiation doses received were recorded. Results: There was a significant difference in the image quality scores between the retrospective and prospective gating protocols (Chi-square = 15.331, p = 0.009). There was no significant difference between the SNRs of the contrasted artery and myocardium in these two groups, but the CNRs were increased in the prospective group. The mean radiation dose of prospective gating group was 2.71 {+-} 0.67 mSv (range, 1.67-3.59 mSv), which was significantly lower than that of the retrospective group (p < 0.001). Conclusion: Prospective CT angiography can achieve lower radiation dose than that of low-dose retrospective CT angiography, with preserved image quality.
In vitro measurement of CT density and estimation of stenosis related to coronary soft plaque at 100 kV and 120 kV on ECG-triggered scan
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Horiguchi, Jun, E-mail: firstname.lastname@example.com [Department of Clinical Radiology, Hiroshima University Hospital, 1-2-3, Kasumi-cho, Minami-ku, Hiroshima 734-8551 (Japan); Fujioka, Chikako, E-mail: firstname.lastname@example.com [Department of Clinical Radiology, Hiroshima University Hospital, 1-2-3, Kasumi-cho, Minami-ku, Hiroshima 734-8551 (Japan); Kiguchi, Masao, E-mail: email@example.com [Department of Clinical Radiology, Hiroshima University Hospital, 1-2-3, Kasumi-cho, Minami-ku, Hiroshima 734-8551 (Japan); Yamamoto, Hideya, E-mail: firstname.lastname@example.com [Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical Sciences and Hiroshima University Hospital, 1-2-3, Kasumi-cho, Minami-ku, Hiroshima 734-8551 (Japan); Shen, Yun, E-mail: email@example.com [CT Lab of Great China, GE Healthcare, L12 and L15, Office Tower, Langham Place, 8 Argyle Street, Mongkok Kowloon (Hong Kong); Kihara, Yasuki, E-mail: email@example.com [Department of Cardiovascular Medicine, Hiroshima University Graduate School of Biomedical Sciences and Hiroshima University Hospital, 1-2-3, Kasumi-cho, Minami-ku, Hiroshima 734-8551 (Japan)
Purpose: The purpose of the study was to compare 100 kV and 120 kV prospective electrocardiograph (ECG)-triggered axial coronary 64-detector CT angiography (64-MDCTA) in soft plaque diagnosis. Materials and methods: Coronary artery models (n = 5) with artificial soft plaques (-32 HU to 53 HU at 120 kV) with three stenosis levels (25%, 50% and 75%) on a cardiac phantom (mimicking slim patient's environment) were scanned in heart rates of 55, 60 and 65 beats per minute (bpm). Four kinds of intracoronary enhancement (205 HU, 241 HU, 280 HU and 314 HU) were simulated. The soft plaque density and the measurement error of stenosis (in percentage), evaluated by two independent observers, were compared between 100 kV and 120 kV. The radiation dose was estimated. Results: Interobserver correlation of the measurement was excellent (density; r = 0.95 and stenosis measure; r = 0.97). Neither the density of soft plaque nor the measurement error of stenosis was different between 100 kV and 120 kV (p = 0.22 and 0.08). The estimated radiation doses were 2.0 mSv and 3.3 mSv (in 14 cm coverage) on 100 kV and 120 kV prospective ECG-triggered axial scans, respectively. Conclusion: The 100 kV prospective ECG-triggered coronary MDCTA has comparable performance to 120 kV coronary CTA in terms of soft plaque densitometry and measurement of stenosis, with a reduced effective dose of 2 mSv.
ECG-triggered MDR-CT for the detection of pulmonary metastases
International Nuclear Information System (INIS)
Pauls, S.; Wahl, J.; Aschoff, A.J.; Brambs, H.J.; Fleiter, T.R.
Purpose: Comparison of multidetector-row CT (MDR-CT) of the chest with and without ECG triggering for the detection of pulmonary metastases. Materials and Methods: Fifty patients with malignant tumors underwent CT of the chest. The unenhanced phase was performed with ECG-triggered MDR-CT and the contrast-enhanced phase with helical MDR-CT. The ECG-triggered and standard helical scans were interpreted in separate sessions, with the analysis determining the number and demarcation of the intrapulmonary nodules and the delineation of the mediastinal structure (rated 1 = excellent to 5 = poor). Results: ECG-MDR-CT images detected 38% more pulmonary nodules than MDR-CT. The detection rate for tumors [de
Comparison between retrospective gating and ECG triggering in magnetic resonance velocity mapping
DEFF Research Database (Denmark)
Søndergaard, L; Ståhlberg, F; Thomsen, C
ECG-triggered cinematographic studies of the cardiovascular system are hampered by several technical restrictions such as the inability to image end-diastole, ghosting, varying signal intensity, and phase contributions from eddy currents. Retrospective gating may solve these problems, but involves...... of flow pulses. However, by reducing the time window retrospectively gated flow measurements were in good agreement with those that are ECG triggered. When fulfilling the demand of a narrow time window for interpolation, retrospective gating offers several advantages in MR velocity mapping....
Assessment of maximal myocardial perfusion by ECG-triggered digital subtraction angiography
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Pijls, N.H.J.; Uijen, G.J.H.; Werf, T. van der (Katholieke Univ. Nijmegen (Netherlands). Cardiology Dept.)
Early studies about calculation of coronary blood flow by analysis of contrast agent passage on the coronary arteriogram were reported more than 2 decades ago by Rutishauser et al. and Smith et al. Thereafter is was shown that visualization of contrast passage through the myocardium could be enhanced by ECG-triggered digital subtraction imaging and it was suggested that myocardial flow could be calculated by studying the temporal changes in contrast intensity in a myocardial region of interest (ROI) as a function of time: the time density curve (TDC). (orig./GDG).
[Axial lumbar interbody fusion: prospective monocentric study].
Stulík, J; Adámek, S; Barna, M; Kaspříková, N; Polanecký, O; Kryl, J
The aim of this prospective study was to evaluate clinical and radiographic results in the patients who underwent L5-S1 fixation using the technique of percutaneous lumbar interbody fusion (AxiaLIF). The study comprised 23 patients, 11 women and 12 men, who ranged from age of 21 to 63 years, with an average of 48.2 years. In all patients surgical posterior stabilisation involving the L5-S1 segment had previously been done. The initial indications for surgery were L5-S1 spondylolisthesis in 20 and L5-S1 spondylosis and stenosis in three patients. The AxiaLIF technique for L5-S1 fixation was indicated in overweight patients and in those after repeated abdominal or retroperitoneal surgery. A suitable position and shape of the sacrum or lumbosacral junction was another criterion. The patients were evaluated between 26 and 56 months (average, 40.4 months) after primary surgery and, on the basis of CT and radiographic findings, bone union and lumbosacral junction stability were assessed. The clinical outcome was investigated using the ODI and VAS systems and the results were statistically analysed by the Wilcoxon test for paired samples with statistical significance set at a level of 0.05. The average VAS value was 6.6 before surgery and, after surgery, 5.2 at three months, 4.2 at six months, 3.1 at one year, 2.9 at two years and 2.1 at three years (n=18). At two post-operative years, improvement in the VAS value by 56.1% was recorded. The average pre-operative ODI value was 25.1; the post-operative values were 17.0 at six months, 12.3 at one year, 10.6 at two years and 8.2 at three years (n=18). At two years after surgery the ODI value improved by 57.8%. To the question concerning their willingness to undergo, with acquired experience, surgery for the same diagnosis, 21 patients (91.3%) gave an affirmative answer. Neither screw breakage nor neurovascular damage or rectal injury was found. CT scans showed complete interbody bone fusion in 22 of the 23 patients (95
Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection
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Li, Jing-Lei, E-mail: firstname.lastname@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Huang, Mei-Ping, E-mail: email@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liang, Chang-Hong, E-mail: firstname.lastname@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhao, Zhen-Jun, E-mail: email@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Hui, E-mail: firstname.lastname@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Cui, Yan-Hai, E-mail: firstname.lastname@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Liu, Qi-Shun, E-mail: email@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Zhang, Jin-E., E-mail: firstname.lastname@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Yang, Lin, E-mail: email@example.com [Department of Radiology, Guangdong Academy of Medical Sciences, Guangdong General Hospital, 106 Zhongshan Er Road, Guangzhou 510080 (China); Ivanc, Thomas B., E-mail: email@example.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States); Yanof, Jeffrey H., E-mail: email@example.com [CT Clinical Science, Philips Healthcare, Highland Heights, OH (United States)
Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R{sup 2} = 0.603). Effective radiation dose was reduced from 16.6 {+-} 0.9 to 9.8 {+-} 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.
Individualized radiation dose control in 256-slice CT coronary angiography (CTCA) in retrospective ECG-triggered helical scans: Using a measure of body size to adjust tube current selection
International Nuclear Information System (INIS)
Li, Jing-Lei; Huang, Mei-Ping; Liang, Chang-Hong; Zhao, Zhen-Jun; Liu, Hui; Cui, Yan-Hai; Liu, Qi-Shun; Zhang, Jin-E.; Yang, Lin; Ivanc, Thomas B.; Yanof, Jeffrey H.
Purpose: To reduce radiation dose for retrospective ECG-triggered helical 256-slice CTCA by determining an optimal body size index to prospectively adjust tube current. Methods: 102 consecutive patients with suspected CAD underwent retrospective ECG-triggered CTCA using 256-slice CT scanner. Six body size indexes including BMI, nipple level (NL) bust, thoracic anteroposterior diameter at NL, chest circumference (CC) at NL, left main and right coronary artery (RCA) origin level were measured and their correlation with noise was evaluated using linear regression. An equation was developed to use this index to adjust tube current. Additional 102 consecutive patients were scanned with the index-based mA s adjustment. A t-test for independent samples was used to compare radiation dose levels with and without the index-based mA s selection method. Results: Linear regression indicated that CC RCA had the best correlation with noise (R 2 = 0.603). Effective radiation dose was reduced from 16.6 ± 0.9 to 9.8 ± 2.7 mSv (p < 0.01), i.e. 40.9% lower dose with the CC RCA-adapted tube current method. The image quality scores indicated no significant difference with and without the size-based mA s selection method. Conclusion: An accessible measure of body size, such as CC RCA, can be used to adapt tube current for individualized radiation dose control.
Combined 201Th myocardial scintiscanning and ECG-triggered ventricular scintiscanning for an evaluation of the left ventricular function after myocardial infarction
International Nuclear Information System (INIS)
Nuetzel, W.
74 patients in whom old transmural myocardial infarctions had been detected by catheterisation of the heart were examined by 201 Th myocardial scintiscanning and ECG-triggered ventricular scintiscanning. There was a control group of 16 patients where coronary disease was excluded by the catheter examination. The findings of the nuclear methods are compared with those of invasive and non-invasive cardiological diagnostics. Nuclear techniques were more sensitive (95%) than ECG (77%) in detecting old infarctions. In volumina determination, there was a satisfactory correlation with angiography for the telediastolic volume (r = 0.77) and a good correlation for the telesystolic volume (r = 0.84) and the ejection fraction (r = 0.89). (orig./AJ) [de
Evaluation of physiotherapy in a prospective cohort of early axial spondyloarthritis. Data from the DESIR cohort.
Escalas, Cécile; Dalichampt, Marie; Dougados, Maxime; Poiraudeau, Serge
To evaluate the effect of physiotherapy on functional limitation in an observational cohort of early axial spondyloarthritis. prospective population-based cohort study. 708 patients with early axial spondyloarthritis between 2007 and 2010 naive of TNF blockers. early physiotherapy defined by at least eight supervised sessions of physical therapy during the first six months. the primary outcome was functional improvement defined by a relative improvement of at least 20% in BASFI at six months. Secondary outcomes were improvement in BASFI at one and two years and ASAS20 response criteria at six months. a propensity score of having physiotherapy was developed and multivariate analysis using propensity score weighting were used to assess the effect of physiotherapy on outcome. Overall, 166 (24%) patients had physiotherapy during the first six months. After using propensity score weighting, there was no functional improvement on the primary outcome in patients treated with early physical therapy (relative risk [IC95%]: 1.15 [0.91-1.45]). No differences were observed on secondary outcomes (relative risk [IC95%]: 0.94 [0.80-1.11]). It seems there is no functional benefit for patients with early spondyloarthritis to be treated early by physiotherapy in daily practice, even though the efficacy of physiotherapy has been shown in several randomized controlled studies. Copyright © 2015 Société française de rhumatologie. Published by Elsevier SAS. All rights reserved.
Divergent axial morphogenesis and early shh expression in vertebrate prospective floor plate
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Stanislav Kremnyov
Full Text Available Abstract Background The notochord has organizer properties and is required for floor plate induction and dorsoventral patterning of the neural tube. This activity has been attributed to sonic hedgehog (shh signaling, which originates in the notochord, forms a gradient, and autoinduces shh expression in the floor plate. However, reported data are inconsistent and the spatiotemporal development of the relevant shh expression domains has not been studied in detail. We therefore studied the expression dynamics of shh in rabbit, chicken and Xenopus laevis embryos (as well as indian hedgehog and desert hedgehog as possible alternative functional candidates in the chicken. Results Our analysis reveals a markedly divergent pattern within these vertebrates: whereas in the rabbit shh is first expressed in the notochord and its floor plate domain is then induced during subsequent somitogenesis stages, in the chick embryo shh is expressed in the prospective neuroectoderm prior to the notochord formation and, interestingly, prior to mesoderm immigration. Neither indian hedgehog nor desert hedgehog are expressed in these midline structures although mRNA of both genes was detected in other structures of the early chick embryo. In X. laevis, shh is expressed at the beginning of gastrulation in a distinct area dorsal to the dorsal blastopore lip and adjacent to the prospective neuroectoderm, whereas the floor plate expresses shh at the end of gastrulation. Conclusions While shh expression patterns in rabbit and X. laevis embryos are roughly compatible with the classical view of "ventral to dorsal induction" of the floor plate, the early shh expression in the chick floor plate challenges this model. Intriguingly, this alternative sequence of domain induction is related to the asymmetrical morphogenesis of the primitive node and other axial organs in the chick. Our results indicate that the floor plate in X. laevis and chick embryos may be initially
Coronary artery visibility in free-breathing young children with congenital heart disease on cardiac 64-slice CT: dual-source ECG-triggered sequential scan vs. single-source non-ECG-synchronized spiral scan
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Goo, Hyun Woo; Yang, Dong Hyun [University of Ulsan College of Medicine, Department of Radiology and Research Institute of Radiology, Asan Medical Center, Seoul (Korea, Republic of)
The potential impact of dual-source ECG-triggered sequential CT scan on coronary artery visibility has not been evaluated in free-breathing young children. To compare coronary artery visibility in free-breathing young children with congenital heart disease on cardiac 64-slice CT between dual-source ECG-triggered sequential (DSET) scan and single-source non-ECG-synchronized spiral (SSNE) scan. In 93 young children, 108 cardiac 64-slice CT examinations were performed during free-breathing. Visibility of coronary arteries and side branches was compared between SSNE and DSET scans. Heart rates and trigger delays for DSET scan were recorded. Effective dose of each scan technique was calculated. Visual grades were significantly higher (P < 0.001 or =0.011) on DSET scan than on SSNE scan except for the distal left anterior descending artery. Coronary arteries were traceable in 79.3% on DSET scan and 54.3% on SSNE scan in the overlapped scan range (P < 0.0001), and 97.1% and 71.9% for the origins and proximal segments (P < 0.0001). Visibility of side branches was improved on DSET scan by a factor of 2.0. Heart rates and trigger delays for DSET scan were 131 {+-} 24 beats per min and 199 {+-} 44 ms, respectively. Effective doses of DSET and SSNE scans were 0.36 {+-} 0.12 mSv and 0.99 {+-} 0.23 mSv, respectively. DSET scan improves visibility of coronary arteries on cardiac 64-slice CT in free-breathing young children with congenital heart disease, compared with SSNE scan. (orig.)
Coronary Artery Stent Evaluation Using a Vascular Model at 64-Detector Row CT: Comparison between Prospective and Retrospective ECG-Gated Axial Scans
International Nuclear Information System (INIS)
Suzuki, Shigeru; Furui, Shigeru; Kaminaga, Tatsuro; Miyazawa, Akiyoshi; Ueno, Yasunari; Konno, Kumiko; Kuwahara, Sadatoshi; Mehta, Dhruv
We wanted to evaluate the performance of prospective electrocardiogram (ECG)-gated axial scans for assessing coronary stents as compared with retrospective ECG-gated helical scans. As for a vascular model of the coronary artery, a tube of approximately 2.5-mm inner diameter was adopted and as for stents, three (Bx-Velocity, Express2, and Micro Driver) different kinds of stents were inserted into the tube. Both patent and stenotic models of coronary artery were made by instillating different attenuation (396 vs. 79 Hounsfield unit [HU]) of contrast medium within the tube in tube model. The models were scanned with two types of scan methods with a simulated ECG of 60 beats per minute and using display field of views (FOVs) of 9 and 18 cm. We evaluated the in-stent stenosis visually, and we measured the attenuation values and the diameter of the patent stent lumen. The visualization of the stent lumen of the vascular models was improved with using the prospective ECG-gated axial scans and a 9-cm FOV. The inner diameters of the vascular models were underestimated with mean measurement errors of -1.10 to -1.36 mm. The measurement errors were smaller with using the prospective ECG-gated axial scans (Bx-Velocity and Express2, p < 0.0001; Micro Driver, p = 0.0004) and a 9-cm FOV (all stents: p < 0.0001), as compared with the other conditions, respectively. The luminal attenuation value was overestimated in each condition. For the luminal attenuation measurement, the use of prospective ECG-gated axial scans provided less measurement error compared with the retrospective ECG-gated helical scans (all stents: p < 0.0001), and the use of a 9-cm FOV tended to decrease the measurement error. The visualization of coronary stents is improved by the use of prospective ECG-gated axial scans and using a small FOV with reduced blooming artifacts and increased spatial resolution
Detection of Airway Anomalies in?Pediatric?Patients with Cardiovascular Anomalies with Low Dose Prospective ECG-Gated Dual-Source CT
Jiao, Hui; Xu, Zhuodong; Wu, Lebin; Cheng, Zhaoping; Ji, Xiaopeng; Zhong, Hai; Meng, Chen
OBJECTIVES: To assess the feasibility of low-dose prospective ECG-gated dual-source CT (DSCT) in detecting airway anomalies in pediatric patients with cardiovascular anomalies compared with flexible tracheobronchoscopy (FTB). METHODS: 33 pediatrics with respiratory symptoms who had been revealed cardiovascular anomalies by transthoracic echocardiography underwent FTB and contrast material-enhanced prospective ECG-triggering CT were enrolled. The study was approved by our institution review bo...
Prosthesis alignment affects axial rotation motion after total knee replacement: a prospective in vivo study combining computed tomography and fluoroscopic evaluations
Directory of Open Access Journals (Sweden)
Harman Melinda K
Full Text Available Abstract Background Clinical consequences of alignment errors in total knee replacement (TKR have led to the rigorous evaluation of surgical alignment techniques. Rotational alignment in the transverse plane has proven particularly problematic, with errors due to component malalignment relative to bone anatomic landmarks and an overall mismatch between the femoral and tibial components' relative positions. Ranges of nominal rotational alignment are not well defined, especially for the tibial component and for relative rotational mismatch, and some studies advocate the use of mobile-bearing TKR to accommodate the resulting small rotation errors. However, the relationships between prosthesis rotational alignment and mobile-bearing polyethylene insert motion are poorly understood. This prospective, in vivo study evaluates whether component malalignment and mismatch affect axial rotation motions during passive knee flexion after TKR. Methods Eighty patients were implanted with mobile-bearing TKR. Rotational alignment of the femoral and tibial components was measured from postoperative CT scans. All TKR were categorized into nominal or outlier groups based on defined norms for surgical rotational alignment relative to bone anatomic landmarks and relative rotational mismatch between the femoral and tibial components. Axial rotation motion of the femoral, tibial and polyethylene bearing components was measured from fluoroscopic images acquired during passive knee flexion. Results Axial rotation motion was generally accomplished in two phases, dominated by polyethylene bearing rotation on the tibial component in early to mid-flexion and then femoral component rotation on the polyethylene articular surface in later flexion. Opposite rotations of the femur-bearing and bearing-baseplate articulations were evident at flexion greater than 80°. Knees with outlier alignment had lower magnitudes of axial rotation and distinct transitions from external to
Axial Globe Position Measurement: A Prospective Multi-center Study by the International Thyroid Eye Disease Society
Bingham, Chad M.; Sivak-Callcott, Jennifer A.; Gurka, Matthew J.; Nguyen, John; Hogg, Jeffery P.; Feldon, Steve E.; Fay, Aaron; Seah, Lay-Leng; Strianese, Diego; Durairaj, Vikram D.; Uddin, Jimmy; Devoto, Martin H.; Harris, Matheson; Saunders, Justin; Osaki, Tammy H.; Looi, Audrey; Teo, Livia; Davies, Brett W.; Elefante, Andrea; Shen, Sunny; Realini, Tony; Fischer, William; Kazim, Michael
Purpose Identify a reproducible measure of axial globe position (AGP) for multicenter studies of patients with thyroid eye disease (TED). Methods This is a prospective, international, multicenter, observational study in which 3 types of AGP evaluation were examined: radiologic, clinical, and photographic. In this study, computed tomography (CT) was the modality to which all other methods were compared. CT AGP was measured from an orthogonal line between the anterior lateral orbital rims to the cornea. All CT measurements were made at a single institution by 3 individual clinicians. Clinical evaluation was performed with exophthalmometry. Three clinicians from each clinical site assessed AGP with 3 different exophthalmometers and horizontal palpebral width using a ruler. Each physician made 3 separate measurements with each type of exophthalmometer, not in succession. All photographic measurements were made at a single institution. AGP was measured from lateral photographs in which a standard marker was placed at the anterior lateral orbital rim. Horizontal and vertical palpebral fissure were measured from frontal photographs. Three trained readers measured 3 separate times, not in succession. Exophthalmometry and photography method validity was assessed by agreement with CT (mean differences calculation, ICC's, Bland-Altman figures). Correlation between palpebral fissure and CT AGP was assessed with Pearson correlation. Intraclinician and interclinician reliability was evaluated using intraclass correlation coefficients (ICC). Results Sixty-eight patients from 7 centers participated. CT mean AGP was 21.37mm (15.96 – 28.90mm) right, 21.22mm (15.87 – 28.70mm) left (ICC 0.996 and 0.995). Exophthalmometry AGP fell between 18mm and 25mm. Intraclinician agreement across exophthalmometers was ideal (ICC 0.948 – 0.983). Agreement between clinicians was greater than 0.85 for all upright exophthalmometry measurements. Photographic mean AGP was 20.47mm (10.92 – 30
Stress-related psychological symptoms contribute to axial pain persistence after motor vehicle collision: path analysis results from a prospective longitudinal study.
Feinberg, Rose K; Hu, JunMei; Weaver, Mark A; Fillingim, Roger B; Swor, Robert A; Peak, David A; Jones, Jeffrey S; Rathlev, Niels K; Lee, David C; Domeier, Robert M; Hendry, Phyllis L; Liberzon, Israel; McLean, Samuel A
Posttraumatic stress disorder (PTSD) symptoms and pain after traumatic events such as motor vehicle collision (MVC) have been proposed to be mutually promoting. We performed a prospective multicenter study that enrolled 948 individuals who presented to the emergency department within 24 hours of MVC and were discharged home after evaluation. Follow-up evaluations were completed 6 weeks, 6 months, and 1 year after MVC. Path analysis results supported the hypothesis that axial pain after MVC consistently promotes the maintenance of hyperarousal and intrusive symptoms, from the early weeks after injury through 1 year. In addition, path analysis results supported the hypothesis that one or more PTSD symptom clusters had an influence on axial pain outcomes throughout the year after MVC, with hyperarousal symptoms most influencing axial pain persistence in the initial months after MVC. The influence of hyperarousal symptoms on pain persistence was only present among individuals with genetic vulnerability to stress-induced pain, suggesting specific mechanisms by which hyperarousal symptoms may lead to hyperalgesia and allodynia. Further studies are needed to better understand the specific mechanisms by which pain and PTSD symptoms enhance one another after trauma, and how such mechanisms vary among specific patient subgroups, to better inform the development of secondary preventive interventions.
Prospective Comparison of F-18 Choline PET/CT Scan Versus Axial MRI for Detecting Bone Metastasis in Biochemically Relapsed Prostate Cancer Patients
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Wouter Huysse
Full Text Available We compared fluor-18 choline positron emission tomography/computed tomography (PET/CT and axial skeleton magnetic resonance imaging (MRI prospectively obtained for the detection of bone metastases in non-castrated patients with biochemically recurrent prostate cancer following primary treatment. PET/CT was performed 45 min post-injection of 3–4 MBq/kg F-18 methyl choline. MRI included T1- and fluid sensitive T2-weighted images of the spine and pelvis. Readers were initially blinded from other results and all scans underwent independent double reading. The best valuable comparator (BVC defined the metastatic status. On the basis of the BVC, 15 out of 64 patients presented with 24 bone metastases. On a patient level, the sensitivity and specificity of MRI and PET were not significantly different. On a lesion level, the sensitivity of MRI was significantly better compared to PET, and the specificity did not differ significantly. In conclusion, axial MRI is an interesting screening tool for the detection of bone metastases because of its low probability of false negative results. However, F-18 choline PET is a valuable addition as it can overrule false positive MRI results and detect non-axial metastases.
Prospectively ECG-triggered high-pitch coronary angiography with third-generation dual-source CT at 70 kVp tube voltage: feasibility, image quality, radiation dose, and effect of iterative reconstruction.
Hell, Michaela M; Bittner, Daniel; Schuhbaeck, Annika; Muschiol, Gerd; Brand, Michael; Lell, Michael; Uder, Michael; Achenbach, Stephan; Marwan, Mohamed
Low tube voltage reduces radiation exposure in coronary CT angiography (CTA). Using 70 kVp tube potential has so far not been possible because CT systems were unable to provide sufficiently high tube current with low voltage. We evaluated feasibility, image quality (IQ), and radiation dose of coronary CTA using a third-generation dual-source CT system capable of producing 450 mAs tube current at 70 kVp tube voltage. Coronary CTA was performed in 26 consecutive patients with suspected coronary artery disease, selected for body weight Image noise was lower in IR vs FBP (60 ± 10 HU vs 74 ± 8 HU; P < .001). In patients <100 kg and with a regular heart rate <60 beats/min, third-generation dual-source CT using high-pitch spiral acquisition and 70 kVp tube voltage is feasible and provides both robust IQ and very low radiation exposure. Copyright © 2014 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.
DEFF Research Database (Denmark)
Witting, Nanna; Andersen, Linda K; Vissing, John
Classically, myopathies are categorized according to limb or cranial nerve muscle affection, but with the growing use of magnetic resonance imaging it has become evident that many well-known myopathies have significant involvement of the axial musculature. New disease entities with selective axial...
Imaging quality and effective radiation dose of prospective ECG-gated axial multidetector row computed tomography coronary angiography
International Nuclear Information System (INIS)
Capunay, C.; Carrascosa, P.; Vallejos, J.; Deviggiano, A.; Pollono, P.M.; Garcia, M.J.
Objective. To determine the imaging quality and effective radiation dose (ERD) of prospective ECG-gated multidetector row computed tomography coronary angiography (PMDCTCA) compared to retrospective ECG-gating (RMDCT-CA). Materials and Methods. Forty-five PMDCT-CA scans were retrospectively reviewed for assessing imaging quality and ERD, and compared to 90 RMDCT-CA scans performed with (n=45) and without (n=45) tube current modulation, selected from our database on the basis of similar demographical characteristics. ERD was compared between all three groups. Imaging quality was assessed by two independent observers and compared to the imaging quality of the group of RMDCT-CA scans performed with tube current modulation. The interobserver variability was also determined. Results. There were no significant differences in imaging quality between the two groups. Interobserver variability was k=0.92 (95 % CI: 0.87-0.96). The ERD (mean ± SD) using PMDCT-CA was 2.88 ± 0.37 mSv compared to 10.50 ± 1.15 mSv (p [es
Impact of Cervical Sagittal Alignment on Axial Neck Pain and Health-related Quality of Life After Cervical Laminoplasty in Patients With Cervical Spondylotic Myelopathy or Ossification of the Posterior Longitudinal Ligament: A Prospective Comparative Study.
Fujiwara, Hiroyasu; Oda, Takenori; Makino, Takahiro; Moriguchi, Yu; Yonenobu, Kazuo; Kaito, Takashi
This is prospective observational study. To prospectively investigate the correlation among axial neck pain; a newly developed patient-based quality of life outcome measure, the Japanese Orthopaedic Association Cervical Myelopathy Evaluation Questionnaire (JOACMEQ); and cervical sagittal alignment after open-door laminoplasty for cervical myelopathy. Many studies have focused on postoperative axial neck pain after laminoplasty. However, the correlation among cervical sagittal alignment, neck pain, and JOACMEQ has not been investigated. In total, 57 consecutive patients treated by open-door laminoplasty for cervical myelopathy were included (mean age, 63.7 y; 15 women and 42 men) and divided into 2 groups according to diagnosis [cervical spondylotic myelopathy (CSM) group: 35 patients, and ossification of the posterior longitudinal ligament (OPLL) group: 22 patients]. JOA score, a subdomain of cervical spine function (CSF) in the JOACMEQ, and the visual analog scale for axial neck pain were assessed preoperatively and 12 months postoperatively. Radiographic cervical sagittal parameters were measured by C2 sagittal vertical axis (C2 SVA), C2-C7 lordosis, C7 sagittal slope (C7 slope), and range of motion. C2 SVA values in both groups shifted slightly anteriorly between preoperative and 12-month postoperative measurements (CSM: +19.7±10.9 mm; OPLL: +22.1±13.4 mm vs. CSM: +23.2±16.1 mm; OPLL: +28.7±15.4 mm, respectively). Postoperative axial neck pain in the OPLL group showed strong negative correlations with C2 SVA and C7 slope. Strong negative correlations were found between axial neck pain and CSF in both the preoperative CSM and OPLL groups (CSM: r=-0.45, P=0.01; OPLL: r=-0.61, Ppain and CSF in the postoperative OPLL group (r=-0.51, P=0.05). This study demonstrated a significant negative correlation between neck pain and CSF in both the CSM and OPLL groups preoperatively and in the OPLL group postoperatively. Radiographic cervical sagittal alignment
International Nuclear Information System (INIS)
Brueckner, K.A.; Lewis, J.H.
The invention relates to axial tomography, sometimes referred to as cross-sectional x-ray. The apparatus described may utilize the conventional x-ray or ultrasonic source and detector and scanning mechanism for producing the plurality of sets of radiation detector output signals. It has the means for storing the detector output signals in analog form with the signals of one set overlying the signals of another set so that signals resulting from radiation through a zone of the object being examined are summed at a corresponding zone in the storage device, typically an electronic storage tube. The summed signals are read from the storage device with a radially inversely proportional reader producing a second signal for storage, again typically in an electronic storage tube. These signals stored in the second storage device are read with Laplacian relation, with the resultant sigal being a video signal that may be connected to a TV monitor for display of the sectional image. In alternative embodiments, optical film systems and electrostatic systems are utilized. (JTA)
Coronary computed tomography angiography using prospective electrocardiography-gated axial scans with 64-detector computed tomography. Evaluation of stair-step artifacts and padding time
International Nuclear Information System (INIS)
Kimura, Fumiko; Umezawa, Tatsuo; Asano, Tomonari; Chihara, Ruri; Nishi, Naoko; Nishimura, Shigeyoshi; Sakai, Fumikazu
We compared stair-step artifacts and radiation dose between prospective electrocardiography (ECG)-gated coronary computed tomography angiography (prospective CCTA) and retrospective CCTA using 64-detector CT and determined the optimal padding time (PT) for prospective CCTA. We retrospectively evaluated 183 patients [mean heart rate (HR) <65 beats/min, maximum HR instability <5 beats/min] who had undergone CCTA. We scored stair-step artifacts from 1 (severe) to 5 (none) and evaluated the effective dose in 53 patients with retrospective CCTA and 130 with prospective CCTA (PT 200 ms, n=32; PT 50 ms, n=98). Mean artifact scores were 4.3 in both retrospective and prospective CCTAs. However, statistically more arteries scored <3 (nonassessable) on prospective CCTA (P<0.001). Mean scores for prospective CCTA with 200- and 50-ms PT were 4.1 and 4.3, respectively (no significant difference). The radiation dose of prospective CCTA was reduced by 59.1% to 80.7%. Prospective CCTA reduces the radiation dose and allows diagnostic imaging in most cases but shows more nonevaluable artifacts than retrospective CCTA. Use of 50-ms instead of 200-ms PT appears to maintain image quality in patients with a mean HR <65 beats/min and HR instability of <5 beats/min. (author)
Prospective electrocardiogram-gated axial 64-detector computed tomographic angiography vs retrospective gated helical technique to assess coronary artery bypass graft anastomosis. Comparison of image quality and patient radiation dose
International Nuclear Information System (INIS)
Machida, Haruhiko; Masukawa, Ai; Tanaka, Isao; Fukui, Rika; Suzuki, Kazufumi; Ueno, Eiko; Kodera, Kojiro; Nakano, Kiyoharu; Shen, Y.
In the present study the effective dose and image quality at distal anastomoses were retrospectively compared between prospective electrocardiogram (ECG)-gated axial and retrospective ECG-gated helical techniques on 64-detector computed tomographic (CT) angiography following coronary artery bypass graft surgery. Following bypass surgery, 52 patients with a heart rate <65 beats/min underwent CT angiography: 26 patients each with prospective and retrospective ECG gating techniques. The effective dose was compared between the 2 groups using a 4-point scale (4, excellent; 1, poor) to grade the quality of curved multiplanar reformation images at distal anastomoses. Patient characteristics of the 2 groups were well matched, and the same CT scan parameters were used for both, except for the interval between surgery and CT examination, tube current, and image noise index. Image quality scores did not differ significantly (3.26±0.95 vs 3.35±0.87; P=0.63), but the effective dose was significantly lower in the prospective (7.3±1.8 mSv) than in the retrospective gating group (23.6±4.5 mSv) (P<0.0001). Following bypass surgery, 64-detector CT angiography using prospective ECG gating is superior to retrospective gating in limiting the radiation dose and maintaining the image quality of distal anastomoses. (author)
Comparative study of image quality and radiation dose between prospective and retrospective ECG gating technique in coronary artery imaging with 64-slice spiral CT
International Nuclear Information System (INIS)
Liu Jianxin; Liu Jian; Dou Yanbin; Wang Jichen; Sun Hongyue
Objective: To compare the image quality and radiation dose between prospective ECG-trigering and retrospective ECG gating technique in coronary artery imaging. Methods: 33 patients suspected coronary artery disease were included in this study and divided into experimental group (prospective ECG-triggering coronary artery imaging, heart rate 0.05). The mean DLP of experimental group (234.4 mGy · cm) was DLP of control group (974.4 mGy · cm) 24.1%. The mean effective dose of prospective ECG gating coronary artery imaging was 3.2 mSv. Effective dose reduced 76.47 %. Conclusions: Prospective ECG gating coronary artery imaging can obtain the similar image quality compared with prospective ECG gating coronary artery imaging but the effective dose reduced 76.47 %. Prospective ECG gating coronary artery imaging has clinical value to peoples who are able to not accept high radiation dose and with low heart rate. (authors)
A Comparison of Macintosh and Airtraq Laryngoscopes for Endotracheal Intubation in Adult Patients With Cervical Spine Immobilization Using Manual In Line Axial Stabilization: A Prospective Randomized Study.
Vijayakumar, Vinodhadevi; Rao, Shwethapriya; Shetty, Nanda
During cervical spine immobilization using Manual In Line Axial Stabilization (MILS), it is difficult to visualize the larynx by aligning the oropharyngeolaryngeal axes using Macintosh laryngoscope. Theoretically, Airtraq an anatomically shaped blade with endotracheal tube guide channel offers advantage over Macintosh. We hypothesized that intubation would be easier and faster with Airtraq compared with Macintosh laryngoscope. Ninety anesthetized adult patients with normal airways were intubated by experienced anesthesiologists after cervical immobilization with MILS either with Macintosh or Airtraq. Primary outcomes compared were successful intubation, and degree of difficulty of intubation as assessed by Intubation Difficulty Scale (IDS) score. Secondary outcomes compared were duration of laryngoscopy and intubation, degree of difficulty of intubation as assessed by Numerical Rating Scale score, soft tissue, and dental trauma. All 90 patients were successfully intubated in the first attempt. Intubation as assessed by IDS score was easier in Airtraq (84.44%) in contrast to slight difficulty in the Macintosh (77.78%) group; Numerical Rating Scale score was easy in both the groups (Airtraq-91.12%; Macintosh-93.34%). The median (interquartile range [IQR]) time for laryngoscopy, (12 s [IQR, 8 to 17.5) vs. 8 s [IQR, 6 to 12]); total duration for intubation (25 s [IQR, 20-33] vs. 22 s [IQR, 18-27.5]) were prolonged in Airtraq group in comparison to Macintosh group. In anesthetized adult patients with MILS compared with Macintosh, Airtraq provides equal success rate of intubation, statistically significant (although clinically insignificant) longer duration for laryngoscopy and intubation. Intubation with Airtraq was significantly easier than Macintosh as assessed by the IDS score.
Image Quality, Overall Evaluability, and Effective Radiation Dose of Coronary Computed Tomography Angiography With Prospective Electrocardiographic Triggering Plus Intracycle Motion Correction Algorithm in Patients With a Heart Rate Over 65 Beats Per Minute.
Pontone, Gianluca; Muscogiuri, Giuseppe; Baggiano, Andrea; Andreini, Daniele; Guaricci, Andrea I; Guglielmo, Marco; Fazzari, Fabio; Mushtaq, Saima; Conte, Edoardo; Annoni, Andrea; Formenti, Alberto; Mancini, Elisabetta; Verdecchia, Massimo; Fusini, Laura; Bonfanti, Lorenzo; Consiglio, Elisa; Rabbat, Mark G; Bartorelli, Antonio L; Pepi, Mauro
Recently, a new intracycle motion correction algorithm (MCA) was introduced to reduce motion artifacts from heart rate (HR) in coronary computed tomography angiography (cCTA). The aim of the study was to evaluate the image quality, overall evaluability, and effective radiation dose (ED) of cCTA with prospective electrocardiographic (ECG) triggering plus MCA as compared with standard protocol with retrospective ECG triggering in patients with HR≥65 bpm. One hundred consecutive patients (67±10 y) scheduled for cCTA with 65Ethics Committee and a written informed consent was obtained from all patients. Image noise, signal to noise ratio, contrast to noise ratio, Likert image quality score (score 1, nondiagnostic; score 2, adequate; score 3, good; score 4, excellent), overall image evaluability, and ED were measured and compared between the 2 groups. Both vessel-based and patient-based analyses were evaluated. Student test or Wilcoxon test were used to evaluate differences of continuous variables, whereas the χ test was used to study differences with regard to categorical data. A P-value <0.05 was considered statistically significant. cCTA was successfully performed in all patients. In a segment-based model, group 1 compared with group 2 showed a lower rate of overall artifacts (67% vs. 83%; P<0.001) and motion artifacts (49% vs. 66%; P<0.001), resulting in a better Likert image quality score (2.83±1.03 vs. 2.37±1.02; P<0.01) and overall evaluability (85% vs. 75%; P<0.01). Group 1 showed a lower ED as compared with group 2 (3.1±1.9 vs. 11.9±3.3 mSv; P<0.01). MCA and cCTA with prospective ECG-triggering acquisition in patients with high HR improves image quality and overall evaluability compared with cCTA with standard retrospective ECG triggering.
Low-dose prospectively electrocardiogram-gated axial dual-source CT angiography in patients with pulsatile bilateral bidirectional Glenn Shunt: an alternative noninvasive method for postoperative morphological estimation.
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Xiaopeng Ji
Full Text Available To explore the clinical value of low-dose prospectively electrocardiogram-gated axial dual-source CT angiography (low-dose PGA scanning, CTA in patients with pulsatile bilateral bidirectional Glenn shunt (bBDG as an alternative noninvasive method for postoperative morphological estimation.Twenty patients with pulsatile bBDG (mean age 4.2±1.6 years underwent both low-dose PGA scanning and conventional cardiac angiography (CCA for the morphological changes. The morphological evaluation included the anatomy of superior vena cava (SVC and pulmonary artery (PA, the anastomotic location, thrombosis, aorto-pulmonary collateral circulation, pulmonary arteriovenous malformations, etc. Objective and subjective image quality was assessed. Bland-Altman analysis and linear regression analyses were used to evaluate the correlation on measurements between CTA and CCA. Effective radiation dose of both modalities was calculated.The CT attenuation value of bilateral SVC and PA was higher than 300 HU. The average subjective image quality score was 4.05±0.69. The morphology of bilateral SVC and PA was displayed completely and intuitively by CTA images. There were 24 SVC above PA and 15 SVC beside PA. Thrombosis was found in 1 patient. Collateral vessels were detected in 13 patients. No pulmonary arteriovenous malformation was found in our study. A strong correlation (R2>0.8, P0.The mean effective dose of CTA and CCA was 0.50±0.17 mSv and 4.85±1.34 mSv respectively.CT angiography with a low-dose PGA scanning is an accurate and reliable noninvasive examination in the assessment of morphological changes in patients with pulsatile bBDG.
International Nuclear Information System (INIS)
Huffer, J.
The purpose of this calculation is to develop axial profiles for estimating the axial variation in burnup of a boiling water reactor (BWR) assembly spent nuclear fuel (SNF) given the average burnup of an assembly. A discharged fuel assembly typically exhibits higher burnup in the center and lower burnup at the ends of the assembly. Criticality safety analyses taking credit for SNF burnup must account for axially varying burnup relative to calculations based on uniformly distributed assembly average burnup due to the under-burned tips. Thus, accounting for axially varying burnup in criticality analyses is also referred to as accounting for the ''end effect'' reactivity. The magnitude of the reactivity change due to ''end effect'' is dependent on the initial assembly enrichment, the assembly average burnup, and the particular axial profile characterizing the burnup distribution. The set of bounding axial profiles should incorporate multiple BWR core designs and provide statistical confidence (95 percent confidence that 95 percent of the population is bound by the profile) that end nodes are conservatively represented. The profiles should also conserve the overall burnup of the fuel assembly. More background on BWR axial profiles is provided in Attachment I
Computerised Axial Tomography (CAT)
Ministry of' Defence, Defence Research Information Centre, UK. Computerised Axial Tomography ( CAT ) Report Secufty C"uMiauion tide Onadtiicadon (U. R, Cor S...DRIC T 8485 COMPUTERISED AXIAL TOMOGRAPHY ( CAT ) F.P. GENTILE, F. SABETTA, V. TRO1* ISS R 78/4.Rome, 1.5 Mlarch 1978 (from Italian) B Distribution(f...dello Radiazioni ISSN 0390--6477 F.P. GENTILE, F. SABETTA. V. TROI Computerised Axial Tomography ( CAT ) March 15, 1978). This paper is a review of
Signatures for axial chromodynamics
International Nuclear Information System (INIS)
Pati, J.C.
Within the context of basic left-right symmetry and the hypothesis of unification of weak, electromagnetic and strong forces at a mass level approximately equal to 10 4 -10 6 GeV, relatively light ''mass'' axial gluons, confined or liberated, must be postulated. The authors remark that the existence of such ''light'' axial gluons supplementing the familiar vector octet preserves the successes of QCD, both for deep inelastic processes and charmonium physics. Through the characteristic spin-spin force, generated by their exchange, they may even help resolve some of the discrepancies between vector QCD predictions and charmonium physics. The main remark of this note is that if colour is liberated, not only vector but also axial-vector gluons are produced in high-energy e - e + experiments, e.g. at PETRA and PEP, with fairly large cross-section. Distinctive decay modes of such liberated axial gluons are noted
128-slice Dual-source Computed Tomography Coronary Angiography in Patients with Atrial Fibrillation: Image Quality and Radiation Dose of Prospectively Electrocardiogram-triggered Sequential Scan Compared with Retrospectively Electrocardiogram-gated Spiral Scan.
Lin, Lu; Wang, Yi-Ning; Kong, Ling-Yan; Jin, Zheng-Yu; Lu, Guang-Ming; Zhang, Zhao-Qi; Cao, Jian; Li, Shuo; Song, Lan; Wang, Zhi-Wei; Zhou, Kang; Wang, Ming
Objective To evaluate the image quality (IQ) and radiation dose of 128-slice dual-source computed tomography (DSCT) coronary angiography using prospectively electrocardiogram (ECG)-triggered sequential scan mode compared with ECG-gated spiral scan mode in a population with atrial fibrillation. Methods Thirty-two patients with suspected coronary artery disease and permanent atrial fibrillation referred for a second-generation 128-slice DSCT coronary angiography were included in the prospective study. Of them, 17 patients (sequential group) were randomly selected to use a prospectively ECG-triggered sequential scan, while the other 15 patients (spiral group) used a retrospectively ECG-gated spiral scan. The IQ was assessed by two readers independently, using a four-point grading scale from excel-lent (grade 1) to non-assessable (grade 4), based on the American Heart Association 15-segment model. IQ of each segment and effective dose of each patient were compared between the two groups. Results The mean heart rate (HR) of the sequential group was 96±27 beats per minute (bpm) with a variation range of 73±25 bpm, while the mean HR of the spiral group was 86±22 bpm with a variationrange of 65±24 bpm. Both of the mean HR (t=1.91, P=0.243) and HR variation range (t=0.950, P=0.350) had no significant difference between the two groups. In per-segment analysis, IQ of the sequential group vs. spiral group was rated as excellent (grade 1) in 190/244 (78%) vs. 177/217 (82%) by reader1 and 197/245 (80%) vs. 174/214 (81%) by reader2, as non-assessable (grade 4) in 4/244 (2%) vs. 2/217 (1%) by reader1 and 6/245 (2%) vs. 4/214 (2%) by reader2. Overall averaged IQ per-patient in the sequential and spiral group showed equally good (1.27±0.19 vs. 1.25±0.22, Z=-0.834, P=0.404). The effective radiation dose of the sequential group reduced significantly compared with the spiral group (4.88±1.77 mSv vs. 10.20±3.64 mSv; t=-5.372, P=0.000). Conclusion Compared with retrospectively
On renormalization of axial anomaly
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Efremov, A.V.; Teryaev, O.V.
It is shown that multiplicative renormalization of the axial singlet current results in renormalization of the axial anomaly in all orders of perturbation theory. It is a necessary condition for the Adler - Bardeen theorem being valid. 10 refs.; 2 figs
International Nuclear Information System (INIS)
An axial tomographic system is described comprising axial tomographic means for collecting sets of data corresponding to the transmission or absorption of a number of beams of penetrating radiation through a planar slice of an object. It includes means to locate an object to be analyzed, a source and detector for directing one or more beams of penetrating radiation through the object from the source to the detector, and means to rotate (and optionally translate) the source as well as means to process the collected sets of data. Data collection, data processing, and data display can each be conducted independently of each other. An additional advantage of the system described is that the raw data (i.e., the originally collected data) are not destroyed by the data processing but instead are retained intact for further reference or use, if needed
Directory of Open Access Journals (Sweden)
Walt Wells
Full Text Available Our objective in this paper is to solve a second order differential equation for a long, simply supported column member subjected to a lateral axial load using Heun's numerical method. We will use the solution to find the critical load at which the column member will fail due to buckling. We will calculate this load using Euler's derived analytical approach for an exact solution, as well as Euler's Numerical Method. We will then compare the three calculated values to see how much they deviate from one another. During the critical load calculation, it will be necessary to calculate the moment of inertia for the column member.
Axial skeletal CT densitometry
International Nuclear Information System (INIS)
Lampmann, L.E.H.
Since the discovery of the Roentgen ray a precise and accurate assessment of bone mineral content has been a challenge to many investigators. A number of methods have been developed but no one satisfied. Considering its technical possibilities computed tomography is very promising in determination of bone mineral content (BMC). The new modality enables BMC estimations in the axial skeletal trabecular bone. CT densitometry can be performed on a normal commercially available third generation whole body CT scanner. No dedicated device in a special clinical set-up is necessary. In this study 106 patients, most of them clinically suspected of osteoporosis, were examined. The new method CT densitometry has been evaluated. The results have been correlated to alternative BMC determination methods. (Auth.)
Cumulative impact of axial, structural, and repolarization ECG findings on long-term cardiovascular mortality among healthy individuals in Japan: National Integrated Project for Prospective Observation of Non-Communicable Disease and its Trends in the Aged, 1980 and 1990.
Inohara, Taku; Kohsaka, Shun; Okamura, Tomonori; Watanabe, Makoto; Nakamura, Yasuyuki; Higashiyama, Aya; Kadota, Aya; Okuda, Nagako; Murakami, Yoshitaka; Ohkubo, Takayoshi; Miura, Katsuyuki; Okayama, Akira; Ueshima, Hirotsugu
Various cohort studies have shown a close association between long-term cardiovascular disease (CVD) outcomes and individual electrocardiographic (ECG) abnormalities such as axial, structural, and repolarization changes. The combined effect of these ECG abnormalities, each assumed to be benign, has not been thoroughly investigated. Community-dwelling Japanese residents from the National Integrated Project for Perspective Observation of Non-Communicable Disease and its Trends in the Aged, 1980-2004 and 1990-2005 (NIPPON DATA80 and 90), were included in this study. Baseline ECG findings were classified using the Minnesota Code and categorized into axial (left axis deviation, clockwise rotation), structural (left ventricular hypertrophy, atrial enlargement), and repolarization (minor and major ST-T changes) abnormalities. The hazard ratios of the cumulative impacts of ECG findings on long-term CVD death were estimated by stratified Cox proportional hazard models, including adjustments for cohort strata. In all, 16,816 participants were evaluated. The average age was 51.2 ± 13.5 years; 42.7% participants were male. The duration of follow up was 300,924 person-years (mean 17.9 ± 5.8 years); there were 1218 CVD deaths during that time. Overall, 4203 participants (25.0%) had one or more categorical ECG abnormalities: 3648 (21.7%) had a single abnormality, and 555 (3.3%) had two or more. The risk of CVD mortality increased as the number of abnormalities accumulated (single abnormality HR 1.29, 95% CI 1.13-1.48; ≥2 abnormalities HR 2.10, 95% CI 1.73-2.53). Individual ECG abnormalities had an additive effect in predicting CVD outcome risk in our large-scale cohort study. © The European Society of Cardiology 2013 Reprints and permissions: sagepub.co.uk/journalsPermissions.nav.
Notari, Alessio
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term $\\frac{\\phi}{f_\\gamma} F \\tilde{F}$, such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density $\\rho_R$, which which can lead to inflation without the need of a flat potential. We analyze the system, for momenta $k$ smaller than the cutoff $f_\\gamma$, including numerically the backreaction. We consider the evolution from a given static initial condition and explicitly show that, if $f_\\gamma$ is smaller than the field excursion $\\phi_0$ by about a factor of at least ${\\cal O} (20)$, there is a friction effect which turns on before that the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of...
Characterization of Multiflux Axial Compressors
International Nuclear Information System (INIS)
Brasnarof, Daniel; Kyung Kyu-Hyung; Rivarola, Martin; Gonzalez Jose; Florido, Pablo; Orellano, Pablo; Bergallo, Juan
In the present work the results of analytical models of performance are compared with experimental data acquired in the multi flux axial compressor test facility, built in The Pilcaniyeu Technological Complex for the SIGMA project.We describe the experimental circuit and the data of the dispersion inside the axial compressor obtained using a tracer gas through one of the annular inlets.The attained results can be used to validate the design code for the multi flux axial compressors and SIGMA industrial plant
Axial gap rotating electrical machine
Direct drive rotating electrical machines with axial air gaps are disclosed. In these machines, a rotor ring and stator ring define an axial air gap between them. Sets of gap-maintaining rolling supports bear between the rotor ring and the stator ring at their peripheries to maintain the axial air gap. Also disclosed are wind turbines using these generators, and structures and methods for mounting direct drive rotating electrical generators to the hubs of wind turbines. In particular, the rotor ring of the generator may be carried directly by the hub of a wind turbine to rotate relative to a shaft without being mounted directly to the shaft.
Study of axial magnetic effect
Energy Technology Data Exchange (ETDEWEB)
Braguta, Victor [IHEP, Protvino, Moscow region, 142284 Russia ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 (Russian Federation); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Chernodub, M. N. [CNRS, Laboratoire de Mathématiques et Physique Théorique, Université François-Rabelais Tours, Fédération Denis Poisson, Parc de Grandmont, 37200 Tours, France Department of Physics and Astronomy, University of Gent, Krijgslaan 281, S9, B-9000 Gent (Belgium); School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Goy, V. A. [School of Natural Sciences, Far Eastern Federal University, Sukhanova street 8, Vladivostok, 690950 (Russian Federation); Landsteiner, K. [Instituto de Física Teórica UAM/CSIC, C/ Nicolás Cabrera 13-15, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid (Spain); Molochkov, A. V. [School of Biomedicine, Far Eastern Federal University, Ajax 10 Building 25, Russian island, Vladivostok, 690922 (Russian Federation); Ulybyshev, M. [ITEP, B. Cheremushkinskaya street 25, Moscow, 117218 Russia Institute for Theoretical Problems of Microphysics, Moscow State University, Moscow, 119899 (Russian Federation)
The Axial Magnetic Effect manifests itself as an equilibrium energy flow of massless fermions induced by the axial (chiral) magnetic field. Here we study the Axial Magnetic Effect in the quenched SU(2) lattice gauge theory with massless overlap fermions at finite temperature. We numerically observe that in the low-temperature hadron phase the effect is absent due to the quark confinement. In the high-temperature deconfinement phase the energy flow is an increasing function of the temperature which reaches the predicted asymptotic T{sup 2} behavior at high temperatures. We find, however, that energy flow is about one order of magnitude lower compared to a theoretical prediction.
Energy Technology Data Exchange (ETDEWEB)
Notari, Alessio [Departament de Física Fondamental i Institut de Ciències del Cosmos, Universitat de Barcelona, Martí i Franquès 1, Barcelona, 08028 Spain (Spain); Tywoniuk, Konrad, E-mail: firstname.lastname@example.com, E-mail: firstname.lastname@example.com [Theoretical Physics Department, CERN, Geneva (Switzerland)
We analyze in detail the background cosmological evolution of a scalar field coupled to a massless abelian gauge field through an axial term φ/ f {sub γ} F ∼ F , such as in the case of an axion. Gauge fields in this case are known to experience tachyonic growth and therefore can backreact on the background as an effective dissipation into radiation energy density ρ{sub R}, which can lead to inflation without the need of a flat potential. We analyze the system, for momenta k smaller than the cutoff f {sub γ}, including the backreaction numerically. We consider the evolution from a given static initial condition and explicitly show that, if f {sub γ} is smaller than the field excursion φ{sub 0} by about a factor of at least O (20), there is a friction effect which turns on before the field can fall down and which can then lead to a very long stage of inflation with a generic potential. In addition we find superimposed oscillations, which would get imprinted on any kind of perturbations, scalars and tensors. Such oscillations have a period of 4–5 efolds and an amplitude which is typically less than a few percent and decreases linearly with f {sub γ}. We also stress that the curvature perturbation on uniform density slices should be sensitive to slow-roll parameters related to ρ{sub R} rather than φ-dot {sup 2}/2 and we discuss the existence of friction terms acting on the perturbations, although we postpone a calculation of the power spectrum and of non-gaussianity to future work and we simply define and compute suitable slow roll parameters. Finally we stress that this scenario may be realized in the axion case, if the coupling 1/ f {sub γ} to U(1) (photons) is much larger than the coupling 1/ f {sub G} to non-abelian gauge fields (gluons), since the latter sets the range of the potential and therefore the maximal allowed φ{sub 0∼} f {sub G}.
Reduction of radiation exposure and improvement of image quality with BMI-adapted prospective cardiac computed tomography and iterative reconstruction
International Nuclear Information System (INIS)
Hosch, Waldemar; Stiller, Wolfram; Mueller, Dirk; Gitsioudis, Gitsios; Welzel, Johanna; Dadrich, Monika; Buss, Sebastian J.; Giannitsis, Evangelos; Kauczor, Hans U.; Katus, Hugo A.; Korosoglou, Grigorios
Purpose: To assess the impact of body mass index (BMI)-adapted protocols and iterative reconstruction algorithms (iDose) on patient radiation exposure and image quality in patients undergoing prospective ECG-triggered 256-slice coronary computed tomography angiography (CCTA). Methods: Image quality and radiation exposure were systematically analyzed in 100 patients. 60 Patients underwent prospective ECG-triggered CCTA using a non-tailored protocol and served as a 'control' group (Group 1: 120 kV, 200 mA s). 40 Consecutive patients with suspected coronary artery disease (CAD) underwent prospective CCTA, using BMI-adapted tube voltage and standard (Group 2: 100/120 kV, 100–200 mA s) versus reduced tube current (Group 3: 100/120 kV, 75–150 mA s). Iterative reconstructions were provided with different iDose levels and were compared to filtered back projection (FBP) reconstructions. Image quality was assessed in consensus of 2 experienced observers and using a 5-grade scale (1 = best to 5 = worse), and signal- and contrast-to-noise ratios (SNR and CNR) were quantified. Results: CCTA was performed without adverse events in all patients (n = 100, heart rate of 47–87 bpm and BMI of 19–38 kg/m 2 ). Patients examined using the non-tailored protocol in Group 1 had the highest radiation exposure (3.2 ± 0.4 mSv), followed by Group 2 (1.7 ± 0.7 mSv) and Group 3 (1.2 ± 0.6 mSv) (radiation savings of 47% and 63%, respectively, p < 0.001). Iterative reconstructions provided increased SNR and CNR, particularly when higher iDose level 5 was applied with Multi-Frequency reconstruction (iDose5 MFR) (14.1 ± 4.6 versus 21.2 ± 7.3 for SNR and 12.0 ± 4.2 versus 18.1 ± 6.6 for CNR, for FBP versus iDose5 MFR, respectively, p < 0.001). The combination of BMI adaptation with iterative reconstruction reduced radiation exposure and simultaneously improved image quality (subjective image quality of 1.4 ± 0.4 versus 1.9 ± 0.5 for Group 2 reconstructed using iDose5 MFR versus
Clinical usefullness of ECG-triggered single photon emission comuter tomography of blood-pool
International Nuclear Information System (INIS)
Eilles, Chr.; Boerner, W.; Strauss, P.; Gerhards, W.; Reiners, Ch.
ECT allows direct measurement of the volume of an organ and imaging without disturbing background-superposition. This makes ECT to an useful instrument for ECG-gated blood-pool imaging. Acquisition is made after the injection of 25 mCi Tc-99m HSA with a rotating Anger-Camera-System. ECG-gated imaging is done for each projection; herewith 50-70 cycles per projection are added according to the phase of the heart-cycle. Transversal-Sections of the heart are reconstructed with filtered-back-projection. For each slice a representative cycle, consisting of 10-16 frames, is computed. As shown by our group before a good quality of the reconstructed images can be obtained. Comparison is made with the results of the ECG-gated blood-pool-ECT, the results of the conventional blood-pool-studies and with the results of Laevo-Cardiography. (Author)
Estimation of radiation exposure of retrospective gated and prospective triggered 128-slice triple-rule-out CT angiography
International Nuclear Information System (INIS)
Ketelsen, Dominik; Fenchel, Michael; Thomas, Christoph; Boehringer, Nadine; Tsiflikas, Ilias; Kaempf, Michael; Claussen, Claus D; Heuschmid, Martin; Buchgeister, Markus
Background: CT has become an important role in the differential diagnosis of acute chest pain to exclude an aortic dissection, pulmonary embolism and acute coronary artery syndrome. However, the additional radiation exposure is a cause of concern and dose saving strategies should be applied, if possible. Purpose: To estimate effective dose of retrospective gated and prospective ECG-triggered triple-rule-out computed tomography angiography (TRO-CTA). Material and Methods: An Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a 128-slice single source scanner. The following scan parameters were used (retrospective ECG-gated): 120 kV, 190 mAs/rot., collimation 128x0.6 mm, rotation time 0.3 s. Protocols with a simulated heart rate (HR) of 60 and 100 bpm were performed using the standard ECG-pulsing as well as MinDose. Additionally, a prospective triggered TRO-CTA was acquired (HR 60 bpm). Results: The estimated effective dose of retrospective ECG-gated TRO-CTA ranged from 7.4-13.4 mSv and from 10.1-17.5 mSv for men and women, respectively. Due to radiosensitive breast tissue, women received a significant increased effective dose of up to 64.7% ± 0.03% (p = 0.028) compared to men. MinDose reduces radiation exposure of up to 33.0% ± 6.5% in comparison to standard ECG-pulsing (p < 0.001). The effective dose increased significantly with lower heart rates (p < 0.001). Prospective ECG-triggered TRO-CTA showed an effective dose of 5.9 mSv and 8.2 mSv for men and women, respectively. Compared to retrospective ECG-gated TRO-CTA a significant dose reduction was observed (p < 0.001). Conclusion: Due to the significant different dose exposure, scan protocols should be specifically adapted in a patient- and problem-oriented manner
Estimation of radiation exposure of retrospective gated and prospective triggered 128-slice triple-rule-out CT angiography
Energy Technology Data Exchange (ETDEWEB)
Ketelsen, Dominik; Fenchel, Michael; Thomas, Christoph; Boehringer, Nadine; Tsiflikas, Ilias; Kaempf, Michael; Claussen, Claus D; Heuschmid, Martin (Dept. of Diagnostic and Interventional Radiology, Univ. Hospital Tuebingen, Tuebingen (Germany)), email: firstname.lastname@example.com; Buchgeister, Markus (Depts. of Radiotherapy and Radiooncology, Univ. Hospital Tuebingen, Tuebingen (Germany))
Background: CT has become an important role in the differential diagnosis of acute chest pain to exclude an aortic dissection, pulmonary embolism and acute coronary artery syndrome. However, the additional radiation exposure is a cause of concern and dose saving strategies should be applied, if possible. Purpose: To estimate effective dose of retrospective gated and prospective ECG-triggered triple-rule-out computed tomography angiography (TRO-CTA). Material and Methods: An Alderson-Rando-phantom equipped with thermoluminescent dosimeters was used for dose measurements. Exposure was performed on a 128-slice single source scanner. The following scan parameters were used (retrospective ECG-gated): 120 kV, 190 mAs/rot., collimation 128x0.6 mm, rotation time 0.3 s. Protocols with a simulated heart rate (HR) of 60 and 100 bpm were performed using the standard ECG-pulsing as well as MinDose. Additionally, a prospective triggered TRO-CTA was acquired (HR 60 bpm). Results: The estimated effective dose of retrospective ECG-gated TRO-CTA ranged from 7.4-13.4 mSv and from 10.1-17.5 mSv for men and women, respectively. Due to radiosensitive breast tissue, women received a significant increased effective dose of up to 64.7% +- 0.03% (p = 0.028) compared to men. MinDose reduces radiation exposure of up to 33.0% +- 6.5% in comparison to standard ECG-pulsing (p < 0.001). The effective dose increased significantly with lower heart rates (p < 0.001). Prospective ECG-triggered TRO-CTA showed an effective dose of 5.9 mSv and 8.2 mSv for men and women, respectively. Compared to retrospective ECG-gated TRO-CTA a significant dose reduction was observed (p < 0.001). Conclusion: Due to the significant different dose exposure, scan protocols should be specifically adapted in a patient- and problem-oriented manner
International Nuclear Information System (INIS)
Beetle, Christopher; Wilder, Shawn
This note describes how to characterize and normalize an axial Killing field on a general Riemannian geometry or four-dimensional Lorentzian geometry. No global assumptions are necessary, such as that the orbits of the Killing field all have period 2π. Rather, any Killing field that vanishes at at least one point necessarily has the expected global properties. (note)
Axial structure of the nucleon
Energy Technology Data Exchange (ETDEWEB)
Veronique Bernard; Latifa Elouadrhiri; Ulf-G Meissner
We review the current status of experimental and theoretical understanding of the axial nucleon structure at low and moderate energies. Topics considered include (quasi)elastic (anti)neutrino-nucleon scattering, charged pion electroproduction off nucleons and ordinary as well as radiative muon capture on the proton.
Axial magnetic field produced by axially and radially magnetized permanent rings
International Nuclear Information System (INIS)
Peng, Q.L.; McMurry, S.M.; Coey, J.M.D.
Axial magnetic fields produced by axially and radially magnetized permanent magnet rings were studied. First, the axial magnetic field produced by a current loop is introduced, from which the axial field generated by an infinitely thin solenoid and by an infinitely thin current disk can be derived. Then the axial fields produced by axially and by radially magnetized permanent magnet rings can be obtained. An analytic formula for the axial fields produced by two axially magnetized rings is given. A permanent magnet with a high axial gradient field is fabricated, the measured results agree with the theoretical calculation very well. As an example, the axial periodic field produced by an arrangement of alternating axially and radially magnetized rings has been discussed
View of the Axial Field Spectrometer
The Axial Field Spectrometer, with the vertical uranium/scintillator calorimeter and the central drift chamber retracted for service. One coil of the Open Axial Field Magnet is just visible to the right.
Axial-Centrifugal Compressor Program
Assembly . .. . .... ..... 33 5 Tie Bolt...... .. .. .. .. . *.. .. .. .. .. .. ... 34 6 Axial Compressor Rotor Assembly Runouts . . .. . 34 7 CCV Blow...1.796 Impeller Slip Factor 'Ce2/U 2 ) .91 Impeller Wheel Speed ft/sec 1992.2 Impellet '.ip Radius in. 3.780 Blade Tip Metal Angle- deg 0 Numbec of Blades...test item to the next Phase V component test. The test vehicle final balance levels and rotor runouts were normal at teardown, and no rubsI were
Evaluation of a Chest Circumference-Adapted Protocol for Low-Dose 128-Slice Coronary CT Angiography with Prospective Electrocardiogram Triggering
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Lu, Chenying; Wang, Zufei; Ji, Jiansong; Wang, Hailin; Hu, Xianghua; Chen, Chunmiao [Department of Radiology, Lishui Central Hospital, The Fifth Affiliated Hospital of Wenzhou Medical College, Lishui, Zhejiang 323000 (China)
To assess the effect of chest circumference-adapted scanning protocol on radiation exposure and image quality in patients undergoing prospective electrocardiogram (ECG)-triggered coronary CT angiography (CCTA). One hundred-eighty-five consecutive patients, who had undergone prospective ECG triggering CCTA with a 128-slice CT, were included in the present study. Nipple-level chest circumference, body weight and height were measured before CT examinations. Patients were divided into four groups based on kV/ref·mAs = 100/200, 100/250, 120/200, and 120/250, when patient's chest circumference was ≤ 85.0 (n = 56), 85.0-90.0 (n = 53), 90.0-95.0 (n = 44), and > 95.0 (n = 32), respectively. Image quality per-segment was independently assessed by two experienced observers. Image noise and attenuation were also measured. Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were calculated. The effective radiation dose was calculated using CT dose volume index and the dose-length product. A significant correlation was observed between patients' chest circumference and body mass index (r = 0.762, p < 0.001). Chest circumference ranged from 74 to 105 cm, and the mean effective radiation dose was 1.9-3.8 mSv. Diagnostic image quality was obtained in 98.5% (2440/2478) of all evaluated coronary segments without any significant differences among the four groups (p = 0.650). No significant difference in image noise was observed among the four groups (p = 0.439), thus supporting the validity of the chest circumference-adapted scanning protocol. However, vessel attenuation, SNR and CNR were significantly higher in the 100 kV groups than in the 120 kV groups (p < 0.05). A measure of chest circumference can be used to adapt tube voltage and current for individualized radiation dose control, with resultant similar image noise and sustained diagnostic image quality.
Electron angular distribution axial channeling
International Nuclear Information System (INIS)
Khokonov, A.Kh.; Khokonov, M.Kh.
Angular distributions of ultra-relativistic electrons are calculated in the assumption about presence of statistical equilibrium. Analysis is based on numerical solution of Fokker-Planck type kinetic equation. It is shown that in contrast to case of amorphous medium, the multiple scattering at axial channeling of negative particles results in self-focusing of the initial beam particles and due to it number of electrons moving at an angles to the chain, which are smaller, than critical angle of channeling, may increase by several times as compared to the initial one
Axially alignable nuclear fuel pellets
International Nuclear Information System (INIS)
Johansson, E.B.; Klahn, D.H.; Marlowe, M.O.
An axially alignable nuclear fuel pellet of the type stacked in end-to-end relationship within a tubular cladding is described. Fuel cladding failures can occur at pellet interface locations due to mechanical interaction between misaligned fuel pellets and the cladding. Mechanical interaction between the cladding and the fuel pellets loads the cladding and causes increased cladding stresses. Nuclear fuel pellets are provided with an end structure that increases plastic deformation of the pellets at the interface between pellets so that lower alignment forces are required to straighten axially misaligned pellets. Plastic deformation of the pellet ends results in less interactions beween the cladding and the fuel pellets and significantly lowers cladding stresses. The geometry of pellets constructed according to the invention also reduces alignment forces required to straighten fuel pellets that are tilted within the cladding. Plastic deformation of the pellets at the pellet interfaces is increased by providing pellets with at least one end face having a centrally-disposed raised area of convex shape so that the mean temperature and shear stress of the contact area is higher than that of prior art pellets
International Nuclear Information System (INIS)
J.M. Acaglione
The purpose of this activity is to develop a representative ''limiting'' axial burnup profile for pressurized water reactors (PWRs), which would encompass the isotopic axial variations caused by different assembly irradiation histories, and produce conservative isotopics with respect to criticality. The effect that the low burnup regions near the ends of spent fuel have on system reactivity is termed the ''end-effect''. This calculation will quantify the end-effects associated with Pressurized Water Reactor (PWR) fuel assemblies emplaced in a hypothetical 21 PWR waste package. The scope of this calculation covers an initial enrichment range of 3.0 through 5.0 wt% U-235 and a burnup range of 10 through 50 GWd/MTU. This activity supports the validation of the process for ensuring conservative generation of spent fuel isotopics with respect to criticality safety applications, and the use of burnup credit for commercial spent nuclear fuel. The intended use of these results will be in the development of PWR waste package loading curves, and applications involving burnup credit. Limitations of this evaluation are that the limiting profiles are only confirmed for use with the B andW 15 x 15 fuel assembly design. However, this assembly design is considered bounding of all other typical commercial PWR fuel assembly designs. This calculation is subject to the Quality Assurance Requirements and Description (QARD) because this activity supports investigations of items or barriers on the Q-list (YMP 2001)
Exact axially symmetric galactic dynamos
Henriksen, R. N.; Woodfinden, A.; Irwin, J. A.
We give a selection of exact dynamos in axial symmetry on a galactic scale. These include some steady examples, at least one of which is wholly analytic in terms of simple functions and has been discussed elsewhere. Most solutions are found in terms of special functions, such as associated Lagrange or hypergeometric functions. They may be considered exact in the sense that they are known to any desired accuracy in principle. The new aspect developed here is to present scale-invariant solutions with zero resistivity that are self-similar in time. The time dependence is either a power law or an exponential factor, but since the geometry of the solution is self-similar in time we do not need to fix a time to study it. Several examples are discussed. Our results demonstrate (without the need to invoke any other mechanisms) X-shaped magnetic fields and (axially symmetric) magnetic spiral arms (both of which are well observed and documented) and predict reversing rotation measures in galaxy haloes (now observed in the CHANG-ES sample) as well as the fact that planar magnetic spirals are lifted into the galactic halo.
Axial vector mass spectrum and mixing angles
International Nuclear Information System (INIS)
Caffarelli, R.V.; Kang, K.
Spectral sum rules of the axial-vector current and axial-vector current-pseudoscalar field are used to study the axial-vector mass spectrum and mixing angles, as well as the decay constants and mixing angles of the pseudoscalar mesons. In general, the result is quite persuasive for the existence of the Jsup(PC) = 1 ++ multiplet in which one has a canonical D-E mixing. (Auth.)
Electric machines with axial magnetic flux
Nuca, I.; Ambros, T.; Burduniuc, M.; Deaconu, S. I.; Turcanu, A.
The paper contains information on the performance of axial machines compared to cylindrical ones. At the same time, various constructive schemes of synchronous electromechanical converters with permanent magnets and asynchronous with short-circuited rotor are presented. In the developed constructions, the aim is to maximize the usage of the material of the stator windings. The design elements of the axial machine magnetic system are presented. The FEMM application depicted the array of the magnetic field of an axial machine.
Centrifugal and axial compressor control
McMillan, Gregory K
Control engineers, mechanical engineers and mechanical technicians will learn how to select the proper control systems for axial and centrifugal compressors for proper throughput and surge control, with a particular emphasis on surge control. Readers will learn to understand the importance of transmitter speed, digital controller sample time, and control valve stroking time in helping to prevent surge. Engineers and technicians will find this book to be a highly valuable guide on compressor control schemes and the importance of mitigating costly and sometimes catastrophic surge problems. It can be used as a self-tutorial guide or in the classroom with the book's helpful end-of-chapter questions and exercises and sections for keeping notes.
Axial channeling in electron diffraction
International Nuclear Information System (INIS)
Ichimiya, A.; Lehmpfuhl, G.
Kossel patterns from Silicon and Niobium were obtained with a convergent electron beam. An intensity maximum in the direction of the zone axes [001] and [111] of Nb was interpreted as axial channeling. The intensity distribution in Kossel patterns was calculated by means of the Bloch wave picture of the dynamical theory of electron diffraction. Particularly zone axis patterns were calculated for different substance-energy combinations and they were compared with experimental observations. The intensity distribution in the calculated Kossel patterns was very sensitive to the model of absorption and it was found that a treatment of the absorption close to the model of Humphreys and Hirsch [Phil. Mag. 18, 115 (1968)] gave the best agreement with the experimental observations. Furthermore it is shown which Bloch waves are important for the intensity distribution in the Kossel patterns, how they are absorbed and how they change with energy. (orig.) [de
Axial channeling of uttrarelativistic electrons
Energy Technology Data Exchange (ETDEWEB)
Telegin, V.I.; Khokonov, M.Kh. (Moskovskij Gosudarstvennyj Univ. (USSR). Nauchno-Issledovatel' skij Inst. Yadernoj Fiziki)
The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements.
Axial channeling of uttrarelativistic electrons
International Nuclear Information System (INIS)
Telegin, V.I.; Khokonov, M.Kh.
The dynamics of motion of ultrarelativistic electrons under axial channeling conditions is investigated. The analysis is based on the solution of the kinetic equation obtained recently by Beloshitsky and Kumakhov. The particle dechanneling function is investigated as depending on the type of a crystal, particle energy and angle of entrance into the single crystal. It is found that for most of the beam the major diffusion mechanism is scattering by electrons. It is shown that an optimal depth range exists for which the fraction of channeled particles sharply increases at the expense of the quasi-channeled particles. In a number of cases the dechanneling length for crystals with high atomic numbers may be greater than that of light elements
Bone Disease in Axial Spondyloarthritis.
Van Mechelen, Margot; Gulino, Giulia Rossana; de Vlam, Kurt; Lories, Rik
Axial spondyloarthritis is a chronic inflammatory skeletal disorder with an important burden of disease, affecting the spine and sacroiliac joints and typically presenting in young adults. Ankylosing spondylitis, diagnosed by the presence of structural changes to the skeleton, is the prototype of this disease group. Bone disease in axial spondyloarthritis is a complex phenomenon with the coexistence of bone loss and new bone formation, both contributing to the morbidity of the disease, in addition to pain caused by inflammation. The skeletal structural changes respectively lead to increased fracture risk and to permanent disability caused by ankylosis of the sacroiliac joints and the spine. The mechanism of this new bone formation leading to ankylosis is insufficiently known. The process appears to originate from entheses, specialized structures that provide a transition zone in which tendon and ligaments insert into the underlying bone. Growth factor signaling pathways such as bone morphogenetic proteins, Wnts, and Hedgehogs have been identified as molecular drivers of new bone formation, but the relationship between inflammation and activation of these pathways remains debated. Long-standing control of inflammation appears necessary to avoid ankylosis. Recent evidence and concepts suggest an important role for biomechanical factors in both the onset and progression of the disease. With regard to new bone formation, these processes can be understood as ectopic repair responses secondary to inflammation-induced bone loss and instability. In this review, we discuss the clinical implications of the skeletal changes as well as the underlying molecular mechanisms, the relation between inflammation and new bone formation, and the potential role of biomechanical stress.
Resolution of axial shear strain elastography
International Nuclear Information System (INIS)
Thitaikumar, Arun; Righetti, Raffaella; Krouskop, Thomas A; Ophir, Jonathan
The technique of mapping the local axial component of the shear strain due to quasi-static axial compression is defined as axial shear strain elastography. In this paper, the spatial resolution of axial shear strain elastography is investigated through simulations, using an elastically stiff cylindrical lesion embedded in a homogeneously softer background. Resolution was defined as the smallest size of the inclusion for which the strain value at the inclusion/background interface was greater than the average of the axial shear strain values at the interface and inside the inclusion. The resolution was measured from the axial shear strain profile oriented at 45 0 to the axis of beam propagation, due to the absence of axial shear strain along the normal directions. The effects of the ultrasound system parameters such as bandwidth, beamwidth and transducer element pitch along with signal processing parameters such as correlation window length (W) and axial shift (ΔW) on the estimated resolution were investigated. The results show that the resolution (at 45 0 orientation) is determined by the bandwidth and the beamwidth. However, the upper bound on the resolution is limited by the larger of the beamwidth and the window length, which is scaled inversely to the bandwidth. The results also show that the resolution is proportional to the pitch and not significantly affected by the axial window shift
Origin of axial current in scyllac
International Nuclear Information System (INIS)
Sugisaki, K.
The origin of the axial current observed in Scyllac (a high beta stellarator experiment) is discussed. A shaped coil and/or helical winding produce rotational transform which links magnetic lines of force to the plasma column and the axial current is induced electromagnetically. This phenomenon is inherent in a pulsed high-beta stellarator. The rotational transform produced by the induced axial current is much smaller than that associated with the l = 1, 0 equilibrium fields. The effect of the axial current on the equilibrium and stability of the plasma column is thus small. It is also shown that the magnetic field shear near a plasma surface is very strong
Radial and axial compression of pure electron
International Nuclear Information System (INIS)
Park, Y.; Soga, Y.; Mihara, Y.; Takeda, M.; Kamada, K.
Experimental studies are carried out on compression of the density distribution of a pure electron plasma confined in a Malmberg-Penning Trap in Kanazawa University. More than six times increase of the on-axis density is observed under application of an external rotating electric field that couples to low-order Trivelpiece-Gould modes. Axial compression of the density distribution with the axial length of a factor of two is achieved by controlling the confining potential at both ends of the plasma. Substantial increase of the axial kinetic energy is observed during the axial compression. (author)
Stochastic quantization for the axial model
International Nuclear Information System (INIS)
Farina, C.; Montani, H.; Albuquerque, L.C.
We use bosonization ideas to solve the axial model in the stochastic quantization framework. We obtain the fermion propagator of the theory decoupling directly the Langevin equation, instead of the Fokker-Planck equation. In the Appendix we calculate explicitly the anomalous divergence of the axial-vector current by using a regularization that does not break the Markovian character of the stochastic process
Health and imaging outcomes in axial spondyloarthritis
Machado, P.M.
This thesis focuses on the assessment and monitoring of health and imaging outcomes in axial spondyloarthritis (SpA) and the relationship between these outcomes. Four major contributions to the understanding and management of axial SpA were made: 1) the improvement and facilitation of the assessment
Axial anomalies of Lifshitz fermions
Bakas, Ioannis
We compute the axial anomaly of a Lifshitz fermion theory with anisotropic scaling z=3 which is minimally coupled to geometry in 3+1 space-time dimensions. We find that the result is identical to the relativistic case using path integral methods. An independent verification is provided by showing with spectral methods that the eta-invariant of the Dirac and Lifshitz fermion operators in three dimensions are equal. Thus, by the integrated form of the anomaly, the index of the Dirac operator still accounts for the possible breakdown of chiral symmetry in non-relativistic theories of gravity. We apply this framework to the recently constructed gravitational instanton backgrounds of Horava-Lifshitz theory and find that the index is non-zero provided that the space-time foliation admits leaves with harmonic spinors. Using Hitchin's construction of harmonic spinors on Berger spheres, we obtain explicit results for the index of the fermion operator on all such gravitational instanton backgrounds with SU(2)xU(1) isom...
Modernity: A new axial (era culture?
Directory of Open Access Journals (Sweden)
Wolfgang Schluchter
Full Text Available The proposition of an axial age, lasting roughly from 800 to 200 B.C. and occurring in major civilizations (China, India, Near East independent of each other, first introduced by Alfred Weber and Karl Jaspers, then further developed by Robert Bellah and S. N. Eisenstadt among others, implied from the outset the question whether there has been a second axial age, leading to modernity, and if so, whether this second axial age consists in a secularization of the achievements of the first axial age. In this article it is argued that the notion of a second axial age is meaningful, but that the emergence of modernity can›t be accounted for in terms of secularization of the achievements of the first axial age. Rather, a new axial principle was institutionalized which separates the modern from the premodern world. This new principle is spelled out with reference to Hans Blumenberg, Charles Taylor and especially Max Weber. The emphasis is on the dialectics of disenchantment and the place of religion in a secular age
Development of submersible axial pump for wastewater
Energy Technology Data Exchange (ETDEWEB)
Yun, Jeong Eui [Kangwon Nat' l Univ., Chuncheon (Korea, Republic of)
This study was performed to develop a high efficiency submersible axial pump for concentration wastewater treatment. To do this, we simulated the effect of some parameters such as the axial twist angle of a blade({beta}), the radial twist angle of a blade({alpha}) and the length of a blade ({iota}) on pump efficiency using commercial code, ANSYS CFX and BladeGen. The results showed that the axial twist angle of a blade({beta}) was the most sensible parameter on the pump efficiency. And the pump efficiency had a maximum at {beta}=20.deg, {alpha}=110.deg and {iota}=240mm.
sizing of wind powered axial flux permanent magnet alternator using
African Journals Online (AJOL)
Oct 4, 2016 ... Keywords: Wind-Power, Axial flux, Axial Flux Permanent Machines (AFPM), Axial Flux Permanent Magnet ... energy for power generation, a high constraint is the .... arrangements as Single-Rotor Single-Stator Structure.
Imaging features suggestive of a conjoined nerve root on routine axial MRI
Energy Technology Data Exchange (ETDEWEB)
Song, Su Jin; Lee, Joon Woo; Kang, Heung Sik [Seoul National University Bundang Hospital, Department of Radiology, Gyeongi-do (Korea); Choi, Ja-Young; Hong, Sung Hwan; Kim, Na Ra [Seoul National University College of Medicine, Department of Radiology, Seoul (Korea); Kim, Ki-Jeong; Chung, Sang-Ki; Kim, Hyun-Jib [Seoul National University Bundang Hospital, Department of Neurosurgery, Gyeongi-Do (Korea)
The purpose of our study is to evaluate imaging features suggestive of a conjoined nerve root on routine axial MRI. Two radiologists and two surgeons retrospectively reviewed the MRI of three cases in which a conjoined nerve root was discovered during operation and found three suggestive signs on routine axial MR images: ''corner'' (asymmetric morphology of the anterolateral corner of the dural sac), ''fat crescent'' (intervening extradural fat between the asymmetric dura and the nerve root), and ''parallel'' signs (visualization of the entire parallel course of the nerve root at the disc level). Two radiologists prospectively found these signs during routine MRI interpretation sessions over a period of 6 months. If one or a combination of signs were noted on axial MR images, contiguous axial scans were additionally obtained. Three cases that were previously found during operations were also included. Prevalence and confidence scores for each sign were assessed on axial T1- and T2-weighted images. Twelve patients showed one or a combination of the three signs, 9 had contiguous axial MR scans. Five cases were confirmed by operation. The prevalence of the corner, fat crescent, and parallel signs were 12 out of 12 (100%), 6 out of 12 (50%), and 8 out of 12 (67.7%) on axial T1-weighted images. The overall diagnostic confidence was higher on T1- than on T2-weighted images (P < 0.05). On routine axial L-spine MRI, corner, fat crescent, and parallel signs are suggestive of and assist in the recognition of a conjoined nerve root. (orig.)
The accuracy of axial length measurements in cases of macula-off retinal detachment.
Abou-Shousha, Mohsen; Helaly, Hany Ahmed; Osman, Ihab Mohamed
To assess the accuracy of axial length measurements in cases of macula-off retinal detachment using different methods (optical biometry, A-scan ultrasound, and combined applanation vector-A/B-scan biometry). This prospective clinical study included 100 eyes of 100 patients who underwent vitrectomy alone or phacovitrectomy for macula-off retinal detachment. All patients included signed an informed consent. Preoperative examination of the patients included recording the axial length measurements using optical biometry, A-scan ultrasound, and combined applanation vector-A/B-scan biometry. The mean postoperative IOLMaster axial length after macular reattachment was 26.11 ± 2.91 mm. The mean preoperative IOLMaster axial length with macula-off was 25.32 ± 2.72 mm. The mean preoperative A-scan axial length with macula-off was 25.29 ± 2.80 mm. The mean preoperative vector-A/B-scan axial length with macula-off was 26.03 ± 2.90 mm. The preoperative vector-A/B-scan mean absolute error was 0.59 ± 0.48 D (range, 0.10-2.25 D). Regular methods (optical biometry and A-scan biometry) of measuring the axial length in cases with a detached macula proved to be variable and less accurate. The vector-A/B-scan offered good measurements of the actual axial length in the patients. This was reflected on more accurate postoperative refractive outcome. Copyright © 2016 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.
African Journals Online (AJOL)
Dr Obe
Sep 1, 1984 ... VERY SLOW SPEED AXIAL MOTION RELUCTANCE MOTOR by. L. A. Agu ... order as that of the screw-thread motor can be obtained. LIST OF .... The n stator have equal non- magnetic spacers .... induction motor. An.
Precision axial translator with high stability.
Bösch, M A
We describe a new type of translator which is inherently stable against torsion and twisting. This concentric translator is also ideally suited for precise axial motion with clearance of the center line.
Axial force measurement for esophageal function testing
DEFF Research Database (Denmark)
Gravesen, Flemming Holbæk; Funch-Jensen, Peter; Gregersen, Hans
force (force in radial direction) whereas the bolus moves along the length of esophagus in a distal direction. Force measurements in the longitudinal (axial) direction provide a more direct measure of esophageal transport function. The technique used to record axial force has developed from external...... force transducers over in-vivo strain gauges of various sizes to electrical impedance based measurements. The amplitude and duration of the axial force has been shown to be as reliable as manometry. Normal, as well as abnormal, manometric recordings occur with normal bolus transit, which have been...... documented using imaging modalities such as radiography and scintigraphy. This inconsistency using manometry has also been documented by axial force recordings. This underlines the lack of information when diagnostics are based on manometry alone. Increasing the volume of a bag mounted on a probe...
Theorem on axially symmetric gravitational vacuum configurations
Energy Technology Data Exchange (ETDEWEB)
Papadopoulos, A; Le Denmat, G [Paris-6 Univ., 75 (France). Inst. Henri Poincare
A theorem is proved which asserts the non-existence of axially symmetric gravitational vacuum configurations with non-stationary rotation only. The eventual consequences in black-hole physics are suggested.
Buoyant Helical Twin-Axial Wire Antenna
February 2017 The below identified patent application is available for licensing. Requests for information should be addressed to...300169 1 of 9 BUOYANT HELICAL TWIN-AXIAL WIRE ANTENNA CROSS REFERENCE TO OTHER PATENT APPLICATIONS [0001] This application is a divisional...application and claims the benefit of the filing date of United States Patent Application No. 14/280,889; filed on May 19, 2014; and entitled "Twin-Axial
Nonperturbative Aspects of Axial Vector Vertex
Institute of Scientific and Technical Information of China (English)
ZONG Hong-Shi; CHEN Xiang-Song; WANG Fan; CHANG Chao-Hsi; ZHAO En-Guang
It is shown how the axial vector current of current quarks is related to that of constituent quarks within the framework of the global color symmetry model.Gluon dressing of the axial vector vertex and the quark self-energy functions are described by the inhomogeneous Bethe-Salpeter equation in the ladder approximation and the Schwinger Dyson equation in the rainbow approximation,respectively.
High temperature co-axial winding transformers
Divan, Deepakraj M.; Novotny, Donald W.
The analysis and design of co-axial winding transformers is presented. The design equations are derived and the different design approaches are discussed. One of the most important features of co-axial winding transformers is the fact that the leakage inductance is well controlled and can be made low. This is not the case in conventional winding transformers. In addition, the power density of co-axial winding transformers is higher than conventional ones. Hence, using co-axial winding transformers in a certain converter topology improves the power density of the converter. The design methodology used in meeting the proposed specifications of the co-axial winding transformer specifications are presented and discussed. The final transformer design was constructed in the lab. Co-axial winding transformers proved to be a good choice for high power density and high frequency applications. They have a more predictable performance compared with conventional transformers. In addition, the leakage inductance of the transformer can be controlled easily to suit a specific application. For space applications, one major concern is the extraction of heat from power apparatus to prevent excessive heating and hence damaging of these units. Because of the vacuum environment, the only way to extract heat is by using a cold plate. One advantage of co-axial winding transformers is that the surface area available to extract heat from is very large compared to conventional transformers. This stems from the unique structure of the co-axial transformer where the whole core surface area is exposed and can be utilized for cooling effectively. This is a crucial issue here since most of the losses are core losses.
Dechanneling function for relativistic axially channeled electrons
International Nuclear Information System (INIS)
Muralev, V.A.; Telegin, V.I.
Behaviour of the x(t) dechanneling function depending on the depth is theoretically studied. Theoretical consideration of x(t) for axial channeled relativistic electrons in anisotropic medium results in two-dimensional kinetic equation with mixed derivatives of the parabolic type. The kinetic equation in the approximation of the continuous Lindchard model for relativistic axial channeled electrons is numerically solved. The depth dependence of the x(t) dechanneling function is obtained [ru
Axial forces in centrifugal compressor couplings
Ivanov, A. N.; Ivanov, N. M.; Yun, V. K.
The article presents the results of the theoretical and experimental investigation of axial forces arising in the toothed and plate couplings of centrifugal compressor shaft lines. Additional loads on the thrust bearing are considered that can develop in the toothed couplings as a result of coupled rotors misalignment. Design relationships to evaluate the level of axial forces and recommendations for their reduction in the operating conditions are given.
Singlet axial constant from QCD sum rules
International Nuclear Information System (INIS)
Belitskij, A.V.; Teryaev, O.V.
We analyze the singlet axial form factor of the proton for small momentum transferred in the framework of QCD sum rules using the interpolating nucleon current which explicitly accounts for the gluonic degrees of freedom. As the result we come to the quantitative prediction of the singlet axial constant. It is shown that the bilocal power corrections play the most important role in the analysis. 21 refs., 3 figs
Computer axial tomography in geosciences
International Nuclear Information System (INIS)
Duliu, Octavian G.
Computer Axial Tomography (CAT) is one of the most adequate non-invasive techniques for the investigation of the internal structure of a large category of objects. Initially designed for medical investigations, this technique, based on the attenuation of X- or gamma-ray (and in some cases neutrons), generates digital images which map the numerical values of the linear attenuation coefficient of a section or of the entire volume of the investigated sample. Shortly after its application in medicine, CAT has been successfully used in archaeology, life sciences, and geosciences as well as for the industrial materials non-destructive testing. Depending on the energy of the utilized radiation as well as on the effective atomic number of the sample, CAT can provide with a spatial resolution of 0.01 - 0.5 mm, quantitative as well as qualitative information concerning local density, porosity or chemical composition of the sample. At present two types of axial Computer Tomographs (CT) are in use. One category, consisting of medical as well as industrial CT is equipped with X-ray tubes while the other uses isotopic gamma-ray sources. CT provided with intense X-ray sources (equivalent to 12-15 kCi or 450-550 TBq) has the advantage of an extremely short running time (a few seconds and even less) but presents some disadvantages known as beam hardening and absorption edge effects. These effects, intrinsically related to the polychromatic nature of the X-rays generated by classical tubes, need special mathematical or physical corrections. A polychromatic X-ray beam can be made almost monochromatic by means of crystal diffraction or by using adequate multicomponent filters, but these devices are costly and considerably diminish the output of X-ray generators. In the case of CT of the second type, monochromatic gamma-rays generated by radioisotopic sources, such as 169 Yb (50.4 keV), 241 Am (59 keV), 192 Ir (310.5 and 469.1 keV ) or 137 Cs (662.7 keV), are used in combination with
Hyperquenched hyaloclastites from Axial Seamount
Zezin, D.; Helo, C.; Richard, D.; Clague, D. A.; Dingwell, D. B.; Stix, J.
We determined apparent cooling rates for basaltic hyaloclastites from Axial caldera, Juan de Fuca Ridge. Samples originate from different stratigraphic layers within the unconsolidated volcaniclastic sequences, on flanks of the volcanic edifice. Water depth is ~1400 m below sea level. The hyaloclastite glass fragments comprise two principal morphologies: (1) angular fragments, and (2) thin glassy melt films interpreted as bubble walls, called deep-sea limu o Pele. A natural cooling rate was estimated for each sample of ~50 carefully selected glass shards. The heat capacity was first measured with a differential scanning calorimeter in two heating scans with heating rates of 20 K/min, and a matching cooling rate between those scans. The fictive temperatures Tf were then determined from both heating cycles, and the natural cooling rate derived by the non-Arrhenian relationship between Tf and cooling rate. All samples display hyperquenched states, manifested in a strong exothermic energy release during the initial heating cycle before reaching the glass transition. Cooling rates range from 10 6.73 K/s to 10 3.94 K/s for the limu, and 10 4.92 K/s to 10 2.34 K/s for the angular fragments. Almost all samples of limu shards show elevated cooling rates compared to their angular counterparts of comparable grain mass. In addition, the exothermic part of the enthalpy curves reveal two superimposed relaxation domains, the main broad exothermal peak, ranging from ~350 K to the onset of the glass transition, and a small subordinate peak/shoulder occurring between 550 K and 700 K. The magnitude of the latter varies from clearly identifiable to nearly absent, and tends to be more pronounced in curves obtained from angular fragments. The main exothermal peak is related to the frozen-in structure of the glass and consequently to its thermal history when passing through the glass transition. The subordinate peak may represent strain rate-induced and tensile stress accumulation
Predictors of Persistent Axial Neck Pain After Cervical Laminoplasty.
Kimura, Atsushi; Shiraishi, Yasuyuki; Inoue, Hirokazu; Endo, Teruaki; Takeshita, Katsushi
Retrospective analysis of prospective data. The aim of this study was to reveal baseline predictors of persistent postlaminoplasty neck pain. Axial neck pain is one of the most common complications after cervical laminoplasty; however, baseline predictors of persistent postlaminoplasty neck pain are unclear. We analyzed data from 156 patients who completed a 2-year follow-up after double-door laminoplasty for degenerative cervical myelopathy. Patients rated the average intensity of axial neck pain in the last month using an 11-point numerical rating scale preoperatively and at the 2-year follow-up. The dependent variable was the presence of moderate-to-severe neck pain (numerical rating scale ≥4) at the 2-year follow-up. The independent variables included patient characteristics, baseline radiological parameters, surgical variables, baseline axial neck pain intensity, and baseline functions, which were measured by the Japanese Orthopaedic Association score and the Short Form-36 survey (SF-36). Logistic regression analysis was performed to identify independent predictors of moderate-to-severe neck pain after laminoplasty. At the 2-year follow-up, 51 patients (32%) had moderate-to-severe neck pain, and 106 patients (68%) had no or mild pain. Univariate analysis revealed that the ratio of cervical anterolisthesis, ratio of current smoking, baseline neck pain intensity, and baseline SF-36 Mental Component Summary differed significantly between the groups. Multivariate logistic regression analysis showed that independent predictors of moderate-to-severe neck pain at the 2-year follow-up include the presence of anterolisthesis, current smoking, moderate-to-severe baseline neck pain, and lower SF-36 Mental Component Summary. The presence of anterolisthesis and moderate-to-severe baseline neck pain were also associated with significantly poorer physical function after surgery. The presence of anterolisthesis was associated not only with the highest odds ratio of
Three-dimensional surface reconstruction imaging for evaluation of congenital heart disease from ECG-triggered MR images
International Nuclear Information System (INIS)
Vannier, M.W.; Laschinger, J.; Knapp, R.H.; Gutierrez, F.R.; Gronnemeyer, S.A.
Three-dimensional surface reconstruction images of the heart and great vessels were produced from contiguous sequences of electrocardiographically triggered MR images in 25 patients with congenital heart disease and in three healthy subjects. The imaging data were semiautomatically processed to separate the epicardial and endocardial surfaces and to define the outline of the enclosed blood volumes on a section by section basis. Images were obtained at 5-mm intervals in patients aged 3 months to 30 years with anomalies of the great vessels, tetralogy of Fallot, septal defects, pulmonary atresia, and other congenital heart malformations. The results were used to facilitate the surgical treatment of these patients and were compared with echocardiographic and cineradiographic studies, and with surgical findings or pathologic specimens. These surface reconstruction images were useful for communicating the results of diagnostic examinations to cardiac surgeons, for sizing and location of intracardiac defects, for imaging the pulmonary venous drainage, and for assessing regional and global function
Are Upper-Body Axial Symptoms a Feature of Early Parkinson's Disease?
Moreau, Caroline; Baille, Guillaume; Delval, Arnaud; Tard, Céline; Perez, Thierry; Danel-Buhl, Nicolas; Seguy, David; Labreuche, Julien; Duhamel, Alain; Delliaux, Marie; Dujardin, Kathy; Defebvre, Luc
Background Axial disorders are considered to appear late in the course of Parkinson's disease (PD). The associated impact on quality of life (QoL) and survival and the lack of an effective treatment mean that understanding and treating axial disorders is a key challenge. However, upper-body axial disorders (namely dysarthria, swallowing and breathing disorders) have never been prospectively assessed in early-stage PD patients. Objectives To characterize upper-body axial symptoms and QoL in consecutive patients with early-stage PD. Methods We prospectively enrolled 66 consecutive patients with early-stage PD (less than 3 years of disease progression) and assessed dysarthria, dysphagia and respiratory function (relative to 36 controls) using both objective and patient-reported outcomes. Results The mean disease duration was 1.26 years and the mean UPDRS motor score was 19.4 out of 108. 74% of the patients presented slight dysarthria (primarily dysprosodia). Men appeared to be more severely affected (i.e. dysphonia). This dysfunction was strongly correlated with low swallowing speed (despite the absence of complaints about dysphagia), respiratory insufficiency and poor QoL. Videofluorography showed that oral-phase swallowing disorders affected 60% of the 31 tested patients and that pharyngeal-phase disorders affected 21%. 24% of the patients reported occasional dyspnea, which was correlated with anxiety in women but not in men. Marked diaphragmatic dysfunction was suspected in 42% of the patients (predominantly in men). Conclusion Upper body axial symptoms were frequent in men with early-stage PD, whereas women presented worst non-motor impairments. New assessment methods are required because currently available tools do not reliably detect these upper-body axial disorders. PMID:27654040
Vector and axial constants of the baryon decuplet
International Nuclear Information System (INIS)
Belyaev, V.M.; Blok, B.Y.; Kogan, Y.I.
On the basis of the QCD sum rules for the polarization operator in external axial and vector fields we determine the vector and axial transition constants in the 3/2 + baryon decuplet. We show that the renormalization of the axial constant is due to the interaction of the external axial field with the quark condensate
Δ(1232) Axial Charge and Form Factors from Lattice QCD
International Nuclear Information System (INIS)
Alexandrou, Constantia; Gregory, Eric B.; Korzec, Tomasz; Koutsou, Giannis; Negele, John W.; Sato, Toru; Tsapalis, Antonios
We present the first calculation on the Δ axial vector and pseudoscalar form factors using lattice QCD. Two Goldberger-Treiman relations are derived and examined. A combined chiral fit is performed to the nucleon axial charge, N to Δ axial transition coupling constant and Δ axial charge.
Using axial magnetized permanent rings to build axial gradient magnetic field
International Nuclear Information System (INIS)
Peng Quanling
Axial field produced by an axially magnetized permanent ring was studied. For two permanent magnet rings, if they are magnetized in the same direction, a nearly uniform axial field can be produced; if they are magnetized in opposite direction, an axial gradient field can be produced in the region between the two permanent rings, with the field strength changing from -B 0 to B 0 . A high gradient axial magnetic field has been built by using two axially magnetized permanent rings, the measured field results agree with the PANDIRA calculation very well. It is desirable that the field gradient can be varied to match various requirements. A method to produce the variable gradient field is presented. Axial gradient field can also be used as a beam focusing facility for linear accelerator if axial periodic field can be produced. Its magnetic field is similar to that of a solenoid, in which, large stray field will leak to the outside environment. A method for shielding the outside stray field is discussed
Optimization of residual heat removal pump axial thrust and axial bearing
International Nuclear Information System (INIS)
Schubert, F.
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies
Optimization of residual heat removal pump axial thrust and axial bearing
Energy Technology Data Exchange (ETDEWEB)
Schubert, F.
The residual heat removal (RHR) pumps of German 1300 megawatt pressurized-water reactor (PWR) power plants are of the single stage end suction type with volute casing or with diffuser and forged circular casing. Due to the service conditions the pumps have to cover the full capacity range as well as a big variation in suction static pressure. This results in a big difference in the axial thrust that has to be borne by the axial bearing. Because these pumps are designed to operate without auxiliary systems (things that do not exist can not fail), they are equipped with antifriction bearings and sump oil lubrication. To minimize the heat production within the bearing casing, a number of PWR plants have pumps with combined axial/radial bearings of the ball type. Due to the fact that the maximum axial thrust caused by static pressure and hydrodynamic forces on the impeller is too big to be borne by that type of axial bearing, the impellers were designed to produce a hydrodynamic axial force that counteracts the static axial force. Thus, the resulting axial thrust may change direction when the static pressure varies.
Improving the lattice axial vector current
International Nuclear Information System (INIS)
Horsley, R.; Perlt, H.; Schiller, A.; Zanotti, J.M.
For Wilson and clover fermions traditional formulations of the axial vector current do not respect the continuum Ward identity which relates the divergence of that current to the pseudoscalar density. Here we propose to use a point-split or one-link axial vector current whose divergence exactly satisfies a lattice Ward identity, involving the pseudoscalar density and a number of irrelevant operators. We check in one-loop lattice perturbation theory with SLiNC fermion and gauge plaquette action that this is indeed the case including order O(a) effects. Including these operators the axial Ward identity remains renormalisation invariant. First preliminary results of a nonperturbative check of the Ward identity are also presented.
Diagnostic value of axial CT scan
International Nuclear Information System (INIS)
Kiuchi, Sousuke
Axial CT scan was used to investigate the radiological details of the temporal bone of 33 patients with chronic otitis media, secondary cholesteatoma, sensorineural hearing loss, Meniere disease, vertigo, facial spasm, and neoplasma. The axial scans showed anatomic details of the temporal bone, and at the same time clearly demonstrated the extent of the soft-tissue masses in the middle ears, as well as the destructions of the ossicles. Bone changes of the anterior walls of the epitympanum and external auditory meatus were more clearly demonstrated than by coronary CT scan. However, the axial scan had the disadvantages in demonstrating the stapes, crista transversa, and the mastoid portion of the facial canal. (author)
Axial Vircator for Electronic Warfare Applications
Directory of Open Access Journals (Sweden)
L. Drazan
Full Text Available This paper deals with a high power microwave generator with virtual cathode – vircator in axial release for electronic warfare applications. The classification of directed energy weapons microwave (DEWM is introduced together with basic block diagrams of a particular class of DEWM. In the paper, methods for designing vircator pulsed power supply, axial vircator structure, measurement methods and experimental results are presented. The vircator in electromagnetic ammunition is powered by magneto-cumulative generator and in weapons for defense of objects (WDO, it is powered by Marx generator. The possible applications of a vircator in the DEWM area are discussed.
Axial loaded MRI of the lumbar spine
Energy Technology Data Exchange (ETDEWEB)
Saifuddin, A. E-mail: email@example.com; Blease, S.; MacSweeney, E
Magnetic resonance imaging is established as the technique of choice for assessment of degenerative disorders of the lumbar spine. However, it is routinely performed with the patient supine and the hips and knees flexed. The absence of axial loading and lumbar extension results in a maximization of spinal canal dimensions, which may in some cases, result in failure to demonstrate nerve root compression. Attempts have been made to image the lumbar spine in a more physiological state, either by imaging with flexion-extension, in the erect position or by using axial loading. This article reviews the literature relating to the above techniques.
Axial nucleon form factors from lattice QCD
International Nuclear Information System (INIS)
Alexandrou, C.; Brinet, M.; Carbonell, J.; Harraud, P. A.; Papinutto, M.; Constantinou, M.; Guichon, P.; Jansen, K.; Korzec, T.
We present results on the nucleon axial form factors within lattice QCD using two flavors of degenerate twisted mass fermions. Volume effects are examined using simulations at two volumes of spatial length L=2.1 fm and L=2.8 fm. Cut-off effects are investigated using three different values of the lattice spacings, namely a=0.089 fm, a=0.070 fm and a=0.056 fm. The nucleon axial charge is obtained in the continuum limit and chirally extrapolated to the physical pion mass enabling comparison with experiment.
The Axially Symmetric One-Monopole
International Nuclear Information System (INIS)
Wong, K.-M.; Teh, Rosy
We present new classical generalized one-monopole solution of the SU(2) Yang-Mills-Higgs theory with the Higgs field in the adjoint representation. We show that this solution with θ-winding number m = 1 and φ-winding number n = 1 is an axially symmetric generalization of the 't Hooft-Polyakov one-monopole. We construct this axially symmetric one-monopole solution by generalizing the large distance asymptotic solutions of the 't Hooft-Polyakov one-monopole to the Jacobi elliptic functions and solving the second order equations of motion numerically when the Higgs potential is vanishing. This solution is a non-BPS solution.
Axial injection in Orsay superconducting cyclotron
International Nuclear Information System (INIS)
Depauw, J.; Kugler, M.F.; Legoff, A.; Potier, J.C.; Richomme, A.; Skowron, R.; Mandrillon, P.; Schapira, J.P.
The compact superconducting cyclotron currently planned at IPN at Orsay is designed for light ion acceleration together with heavy ion acceleration. From the beginning, for this reason, a central geometry able to receive an inflector (to 90deg C) allowing the axial injection of low energy ion beams given by an outer source. The present study is aimed at showing the technical feasibility of theoretical results obtained on axial injection. First experimental study has been made of spatial repartition in three dimensions of electric potential developed by a central geometry of 3 electrodes. Then, the electric study of an electrostatic mirror has been made [fr
Directory of Open Access Journals (Sweden)
Sh. F. Erdes
Full Text Available The clear definition of the concept of «flare in axial spondyloarthritis» is of paramount importance for clinical trials and routine practice in particular. It will be able to unify the characteristics of outcomes over a particular period of time on the one hand and to standardize therapeutic approaches on the other. On 4 February 2016, the journal Annals of Rheumatic Diseases published the on-line paper «Preliminary definitions of 'flare' in axial spondyloarthritis, based on pain, BASDAI and ASDAS-CRP: an ASAS initiative» by L. Gossec et al., which was devoted to this topic.
BPHZL-subtraction scheme and axial gauges
Energy Technology Data Exchange (ETDEWEB)
Kreuzer, M.; Rebhan, A.; Schweda, M.; Piguet, O.
The application of the BPHZL subtraction scheme to Yang-Mills theories in axial gauges is presented. In the auxillary mass formulation we show the validity of the convergence theorems for subtracted momentum space integrals, and we give the integral formulae necessary for one-loop calculations. (orig.).
Accessory caudal axial and pelvic ribs
International Nuclear Information System (INIS)
Bohutova, J.; Kolar, J.; Vitovec, J.; Vyhnanek, L.
Accessory caudal ribs are reported as an extremely curious anomaly in five patients. Once the fracture of this rib was a source of pains after injury. The different shapes of the ribs are documented in this clinical survey which is the most extensive in the present literature. Anomalous ribs arise due to inappropriate segmentation during the embryonal development of the axial skeleton. (orig.) [de
Aryabha~ and Axial Rotation of Earth
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 4. Aryabhata and Axial Rotation of Earth - Naksatra Dina (the Sidereal Day). Amartya Kumar Dutta. General Article Volume 11 Issue 4 April 2006 pp 56-74. Fulltext. Click here to view fulltext PDF. Permanent link:
Aryabhala and Axial Rotation of Earth
Indian Academy of Sciences (India)
Home; Journals; Resonance – Journal of Science Education; Volume 11; Issue 3. Aryabhata and Axial Rotation of Earth - Khagola (The Celestial Sphere). Amartya Kumar Dutta. General Article Volume 11 Issue 3 March 2006 pp 51-68. Fulltext. Click here to view fulltext PDF. Permanent link:
Helical axial injection concept for cyclotrons
Energy Technology Data Exchange (ETDEWEB)
Hudson, E.D.
A concept for an external beam injection system using a helical beam path centered on the cyclotron axis is described. This system could be used to couple two accelerator stages, with or without intermediate stripping, in cases where conventional axial injection or radial injection are not practical.
Helical axial injection concept for cyclotrons
International Nuclear Information System (INIS)
Hudson, E.D.
A concept for an external beam injection system using a helical beam path centered on the cyclotron axis is described. This system could be used to couple two accelerator stages, with or without intermediate stripping, in cases where conventional axial injection or radial injection are not practical
The axial polarizability of nucleons and nuclei
International Nuclear Information System (INIS)
Ericson, M.; Figureau, A.
The part of the static nuclear axial polarizability arising from the nucleonic excitations is derived from the low energy expansion of the πN amplitude. It is shown that the contribution of the Δ intermediate state, though dominant, does not saturate the nucleonic response. A similar effect, though more pronounced, is known to occur for the magnetic susceptibility
Optimisation of efficiency of axial fans
Kruyt, Nicolaas P.; Pennings, P.C.; Faasen, R.
A three-stage research project has been executed to develop ducted axial-fans with increased efficiency. In the first stage a design method has been developed in which various conflicting design criteria can be incorporated. Based on this design method, an optimised design has been determined
Axial crystals macroscopic symmetry and tensor properties
Czech Academy of Sciences Publication Activity Database
Janovec, Václav
Roč. 90, č. 1 (2017), s. 1-10 ISSN 0141-1594 Institutional support: RVO:68378271 Keywords : axial * polar * pseudopolar * chiral * enantiomorphism * optical activity Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 1.060, year: 2016
Review of Axial Burnup Distribution Considerations for Burnup Credit Calculations
International Nuclear Information System (INIS)
Wagner, J.C.; DeHart, M.D.
This report attempts to summarize and consolidate the existing knowledge on axial burnup distribution issues that are important to burnup credit criticality safety calculations. Recently released Nuclear Regulatory Commission (NRC) staff guidance permits limited burnup credit, and thus, has prompted resolution of the axial burnup distribution issue. The reactivity difference between the neutron multiplication factor (keff) calculated with explicit representation of the axial burnup distribution and keff calculated assuming a uniform axial burnup is referred to as the ''end effect.'' This end effect is shown to be dependent on many factors, including the axial-burnup profile, total accumulated burnup, cooling time, initial enrichment, assembly design, and the isotopics considered (i.e., actinide-only or actinides plus fission products). Axial modeling studies, efforts related to the development of axial-profile databases, and the determination of bounding axial profiles are also discussed. Finally, areas that could benefit from further efforts are identified
On the problem of axial anomaly in supersymmetric gauge theories
International Nuclear Information System (INIS)
Kazakov, D.I.
The explicit relation is found between the axial current obeying the Adler-Bardeen theorem and the supersymmetric one belonging to a supermultiplet. It is shown that the axial and superconformal anomalies are consistent in all orders of perturbation theory
Cross-flow filtration and axial filtration
International Nuclear Information System (INIS)
Kraus, K.A.
Two relatively novel alternative solid-liquid-separation techniques of filtration are discussed. In cross-flow filtration, the feed is pumped past the filtering surface. While in axial filtration the filter, mounted on a rotor, is moved with respect to the feed. While large-scale application of the axial filter is still in doubt, it permits with little expenditure of time and money, duplication of many hydrodynamic aspects of cross-flow filtration for fine-particle handling problems. The technique has been applied to municipal wastes, low-level radioactive waste treatment plant, lead removal from industrial wastes, removal of pulp-mill contaminants, textile-mill wastes, and pretreatment of saline waters by lime-soda process in preparation for hyperfiltration. Economics and energy requirements are also discussed
Computerized axial tomography in traumatic cervical lesions
International Nuclear Information System (INIS)
Koyama, Tsunemaro
Although plain computerized axial tomography cannot routinely demonstrate the spinal cord, it does provide excellent visualization of the bony outline of the spinal canal and vertebral column. So it should be reasonable to use this technique in cases of cervical traumatic disorders. In this paper we presented 10 cases of cervical traumatic lesions; 3 atlanto-axial dislocation, 2 cervical canal stenosis, 3 OPLL, 1 intramedullary hematoma and 1 C 2 -neurinoma. In some patients neurologic deficits were induced by cervical trauma. Bony lesions appeared more adequately deliniated than intraspinal lesions, however, in some cases intramedullary changes could also be demonstrated. The use of metrizamide with high resolution CT-scanner could improve the usefullness of this technique. (author)
Ventajas de los motores de flujo axial
Directory of Open Access Journals (Sweden)
Alberto M Basanta Otero
Full Text Available Es importante conocer sobre una familia de motores que a diferencia de los convencionales o tradicionales no presentanun flujo rotatorio radial, denominados motores de flujo axial. Dichos motores presentan altos valores de par motriz abajas velocidades, una alta eficiencia y alta densidad de potencia. Este trabajo constituye un breve análisis dealgunos motores de la referencia bibliográfica. Is important to know about a family of motors that at difference whit the traditional, don't have a rotator radial flux,called, axial flux motors. These motors have high torque for low speed, high efficiency and high power density. Thiswork is a brief analysis of several motors of the bibliographic references.
Internal and external axial corner flows
Kutler, P.; Shankar, V.; Anderson, D. A.; Sorenson, R. L.
The inviscid, internal, and external axial corner flows generated by two intersecting wedges traveling supersonically are obtained by use of a second-order shock-capturing, finite-difference approach. The governing equations are solved iteratively in conical coordinates to yield the complicated wave structure of the internal corner and the simple peripheral shock of the external corner. The numerical results for the internal flows compare favorably with existing experimental data.
Axial flux permanent magnet brushless machines
Gieras, Jacek F; Kamper, Maarten J
Axial Flux Permanent Magnet (AFPM) brushless machines are modern electrical machines with a lot of advantages over their conventional counterparts. They are being increasingly used in consumer electronics, public life, instrumentation and automation system, clinical engineering, industrial electromechanical drives, automobile manufacturing industry, electric and hybrid electric vehicles, marine vessels and toys. They are also used in more electric aircrafts and many other applications on larger scale. New applications have also emerged in distributed generation systems (wind turbine generators
Axial gravity, massless fermions and trace anomalies
Energy Technology Data Exchange (ETDEWEB)
Bonora, L. [International School for Advanced Studies (SISSA), Trieste (Italy); KEK, Tsukuba (Japan). KEK Theory Center; INFN, Sezione di Trieste (Italy); Cvitan, M.; Giaccari, S.; Stemberga, T. [Zagreb Univ. (Croatia). Dept. of Physics; Prester, P.D. [Rijeka Univ. (Croatia). Dept. of Physics; Pereira, A.D. [UERJ-Univ. Estadual do Rio de Janeiro (Brazil). Dept. de Fisica Teorica; UFF-Univ. Federal Fluminense, Niteroi (Brazil). Inst. de Fisica
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones. (orig.)
Axial gravity, massless fermions and trace anomalies
International Nuclear Information System (INIS)
Bonora, L.; Cvitan, M.; Giaccari, S.; Stemberga, T.; Prester, P.D.; Pereira, A.D.; UFF-Univ. Federal Fluminense, Niteroi
This article deals with two main topics. One is odd parity trace anomalies in Weyl fermion theories in a 4d curved background, the second is the introduction of axial gravity. The motivation for reconsidering the former is to clarify the theoretical background underlying the approach and complete the calculation of the anomaly. The reference is in particular to the difference between Weyl and massless Majorana fermions and to the possible contributions from tadpole and seagull terms in the Feynman diagram approach. A first, basic, result of this paper is that a more thorough treatment, taking account of such additional terms and using dimensional regularization, confirms the earlier result. The introduction of an axial symmetric tensor besides the usual gravitational metric is instrumental to a different derivation of the same result using Dirac fermions, which are coupled not only to the usual metric but also to the additional axial tensor. The action of Majorana and Weyl fermions can be obtained in two different limits of such a general configuration. The results obtained in this way confirm the previously obtained ones. (orig.)
Golimumab for the treatment of axial spondyloarthritis.
Palazzi, Carlo; D'angelo, Salvatore; Gilio, Michele; Leccese, Pietro; Padula, Angela; Olivieri, Ignazio
Anti-TNF drugs have represented an epochal revolution in the treatment of rheumatoid arthritis and spondyloarthritis. In the field of axial spondyloarthritis, golimumab, a fully human monoclonal anti-TNFα administered subcutaneously every 4 weeks, has shown significant efficacy and good safety in patients with ankylosing spondylitis. More recently, it was also indicated as an effective treatment for patients suffering from non-radiographic axial spondyloarthitits. Areas covered: A systematic literature search was completed, using the largest electronic databases (Medline, Embase and Cochrane), with the aim to review all data concerning the administration of golimumab in patients suffering from axial spondyloartritis. Expert opinion: In the 16-week GO-AHEAD study, golimumab was effective in patients with non-radiographic spondyloarthritis with high levels of CRP and/or positive MRI findings, but not in subjects with both negative CRP and MRI. This finding allows for the addressing the of anti-TNF treatment more specifically. Preliminary data concerning an open-label extension of the GO-AHEAD study outlined the high retention-rate of the drug at 52 weeks. The production of antibodies against golimumab is rare and it seems to exert scarce influence on the drug performances. In conclusion, golimumab appears as a very useful and well tolerated anti-TNF agent.
Computational analysis of a multistage axial compressor
Mamidoju, Chaithanya
Turbomachines are used extensively in Aerospace, Power Generation, and Oil & Gas Industries. Efficiency of these machines is often an important factor and has led to the continuous effort to improve the design to achieve better efficiency. The axial flow compressor is a major component in a gas turbine with the turbine's overall performance depending strongly on compressor performance. Traditional analysis of axial compressors involves throughflow calculations, isolated blade passage analysis, Quasi-3D blade-to-blade analysis, single-stage (rotor-stator) analysis, and multi-stage analysis involving larger design cycles. In the current study, the detailed flow through a 15 stage axial compressor is analyzed using a 3-D Navier Stokes CFD solver in a parallel computing environment. Methodology is described for steady state (frozen rotor stator) analysis of one blade passage per component. Various effects such as mesh type and density, boundary conditions, tip clearance and numerical issues such as turbulence model choice, advection model choice, and parallel processing performance are analyzed. A high sensitivity of the predictions to the above was found. Physical explanation to the flow features observed in the computational study are given. The total pressure rise verses mass flow rate was computed.
Axial Dispersion during Hanford Saltcake Washing
International Nuclear Information System (INIS)
Josephson, Gary B.; Geeting, John GH; Lessor, Delbert L.; Barton, William B.
Clean up of Hanford salt cake wastes begins with dissolution retrieval of the sodium rich salts that make up the dominant majority of mass in the tanks. Water moving through the porous salt cake dissolves the soluble components and also displaces the soluble radionuclides (e.g. 137Cs and 99TcO4- ). The separation that occurs from this displacement, known as Selective dissolution, is an important component in Hanford?s pretreatment of low activity wastes for subsequent Supplemental treatment. This paper describes lab scale testing conducted to evaluate Selective dissolution of cesium from non-radioactive Hanford tank 241-S-112 salt cake simulant containing the primary chemicals found the actual tank. An modified axial dispersion model with increasing axial dispersion was developed to predict cesium removal. The model recognizes that water dissolves the salt cake during washing, which causes an increase in the axial dispersion during the wash. This model was subsequently compared with on-line cesium measurements from the retrieval of tank 241-S-112. The model had remarkably good agreement with both the lab scale and full scale data
Bessel beam CARS of axially structured samples
Heuke, Sandro; Zheng, Juanjuan; Akimov, Denis; Heintzmann, Rainer; Schmitt, Michael; Popp, Jürgen
We report about a Bessel beam CARS approach for axial profiling of multi-layer structures. This study presents an experimental implementation for the generation of CARS by Bessel beam excitation using only passive optical elements. Furthermore, an analytical expression is provided describing the generated anti-Stokes field by a homogeneous sample. Based on the concept of coherent transfer functions, the underling resolving power of axially structured geometries is investigated. It is found that through the non-linearity of the CARS process in combination with the folded illumination geometry continuous phase-matching is achieved starting from homogeneous samples up to spatial sample frequencies at twice of the pumping electric field wave. The experimental and analytical findings are modeled by the implementation of the Debye Integral and scalar Green function approach. Finally, the goal of reconstructing an axially layered sample is demonstrated on the basis of the numerically simulated modulus and phase of the anti-Stokes far-field radiation pattern.
Dynamic control of knee axial deformities
Directory of Open Access Journals (Sweden)
E. E. Malyshev
Full Text Available The authors have evaluated the clinical examination of the patients with axial malalignments in the knee by the original method and device which was named varovalgometer. The measurements were conducted by tension of the cord through the spina iliaca anterior superior and the middle of the lower pole of patella. The deviation of the center of the ankle estimated by metal ruler which was positioned perpendicular to the lower leg axis on the level of the ankle joint line. The results of comparison of our method and computer navigation in 53 patients during the TKA show no statistically significant varieties but they differ by average 5° of valgus in clinical examination in comparison with mechanical axis which was identified by computer navigation. The dynamic control of axial malalignment can be used in clinical practice for estimation of the results of treatment of pathology with axial deformities in the knee; for the control of reduction and secondary displacement of the fractures around the knee; for assessment of instability; in planning of correctional osteotomies and intraoperative control of deformity correction; for estimation of Q angle in subluxation and recurrent dislocation of patella; in planning of TKA; during the growth of child it allows to assess the progression of deformity.
Axial anomaly at finite temperature and finite density
International Nuclear Information System (INIS)
Qian Zhixin; Su Rukeng; Yu, P.K.N.
The U(1) axial anomaly in a hot fermion medium is investigated by using the real time Green's function method. After calculating the lowest order triangle diagrams, we find that finite temperature as well as finite fermion density does not affect the axial anomaly. The higher order corrections for the axial anomaly are discussed. (orig.)
The deep structure of Axial Volcano
West, Michael Edwin
The subsurface structure of Axial Volcano, near the intersection of the Juan de Fuca Ridge and the Cobb-Eickelberg seamount chain in the northeast Pacific, is imaged from an active source seismic experiment. At a depth of 2.25 to 3.5 km beneath Axial lies an 8 km x 12 km region of very low seismic velocities that can only be explained by the presence of magma. In the center of this magma storage chamber at 2--3.5 km below sea floor, the crust is at least 10--20% melt. At depths of 4--5 km there is evidence of additional low concentrations of magma (a few percent) over a larger area. In total, 5--11 km3 of magma are stored in the mid-crust beneath Axial. This is more melt than has been positively identified under any basaltic volcano on Earth. It is also far more than the 0.1--0.2 km3 emplaced during the 1998 eruption. The implied residence time in the magma reservoir of a few hundred to a few thousand years agrees with geochemical trends which suggest prolonged storage and mixing of magmas. The large volume of melt bolsters previous observations that Axial provides much of the material to create crust along its 50 km rift zones. A high velocity ring-shaped feature sits above the magma chamber just outside the caldera walls. This feature is believed to be the result of repeated dike injections from the magma body to the surface during the construction of the volcanic edifice. A rapid change in crustal thickness from 8 to 11 km within 15 km of the caldera implies focused delivery of melt from the mantle. The high flux of magma suggests that melting occurs deeper in the mantle than along the nearby ridge. Melt supply to the volcano is not connected to any plumbing system associated with the adjacent segments of the Juan de Fuca Ridge. This suggests that, despite Axial's proximity to the ridge, the Cobb hot spot currently drives the supply of melt to the volcano.
A new strategy of axial power distribution control based on three axial offsets concept
International Nuclear Information System (INIS)
Shimazu, Yoichiro
We have proposed a very simple control procedure for axial xenon oscillation control based on a characteristic trajectory. The trajectory is drawn by three offsets of power distributions, namely, AOp, AOi and AOx. They are defined as the offset of axial power distribution, the offset of the power distribution under which the current iodine distribution is obtained as the equilibrium and that for xenon distribution, respectively. When these offsets are plotted on X-Y plane for (AOp-AOx, AOi-AOx) the trajectory draws a quite characteristic ellipse (or an elliptic spiral). On the other hands, Constant Axial Offset Control (CAOC) procedure is adopted as axial power distribution control strategy during both base load and load following operations in domestic PWRs. In the previous paper, we have presented an innovative procedure of axial power distribution control during load following in PWRs based on this trajectory such that the AOp-AOx is to be controlled to zero when the value deviates the pre-determined limiting values. In this paper we propose a modified control strategy to get more stability of axial power distributions. In this strategy, we control the trajectory to be close to the major axis of the ellipse when the power distribution reaches the limiting values. In other words, the plot is not controlled only to reduce AOp-AOx but also AOi-AOx is taken into account at the same time. It is known that when the plot is controlled to the major axis, it means that the point gives the peak position of axial xenon oscillation. Therefore xenon oscillation will not increase its amplitude any more. Thus more stable axial power distribution control is attained. This kind of design concept is quite important especially for the future PWRs with elongated fuel length and longer core life. Because in a longer effective core and also the longer core life, it has been known that the stability of axial xenon oscillation becomes more unstable. In this paper, some simulation
Intrinsic carpal ligaments on MR and multidetector CT arthrography: comparison of axial and axial oblique planes
Energy Technology Data Exchange (ETDEWEB)
Lee, Ryan K.L.; Griffith, James F.; Ng, Alex W.H.; Law, Eric K.C. [The Chinese University of Hong Kong, Department of Imaging and Interventional Radiology, Prince Of Wales Hospital, Hong Kong (China); Tse, W.L.; Wong, Clara W.Y.; Ho, P.C. [The Chinese University of Hong Kong, Department of Orthopedics and Traumatology, Prince Of Wales Hospital, Hong Kong (China)
To compare axial and oblique axial planes on MR arthrography (MRA) and multidetector CT arthrography (CTA) to evaluate dorsal and volar parts of scapholunate (SLIL) and lunotriquetral interosseous (LTIL) ligaments. Nine cadaveric wrists of five male subjects were studied. The visibility of dorsal and volar parts of the SLIL and LTIL was graded semi-quantitatively (good, intermediate, poor) on MRA and CTA. The presence of a ligament tear was determined on arthrosocopy and sensitivity, specificity and accuracy of tear detection were calculated. Oblique axial imaging was particularly useful for delineating dorsal and volar parts of the LTIL on MRA with overall 'good' visibility increased from 11 % to 78 %. The accuracy of MRA and CTA in revealing SLIL and LTIL tear was higher using the oblique axial plane. The overall accuracy for detecting SLIL tear on CTA improved from 94 % to 100 % and from 89 % to 94 % on MRA; the overall accuracy of detecting LTIL tear on CTA improved from 89 % to 100 % and from 72 % to 89 % on MRA Oblique axial imaging during CT and MR arthrography improves detection of tears in the dorsal and volar parts of both SLIL and LTIL. (orig.)
Axial flow heat exchanger devices and methods for heat transfer using axial flow devices
Koplow, Jeffrey P.
Systems and methods described herein are directed to rotary heat exchangers configured to transfer heat to a heat transfer medium flowing in substantially axial direction within the heat exchangers. Exemplary heat exchangers include a heat conducting structure which is configured to be in thermal contact with a thermal load or a thermal sink, and a heat transfer structure rotatably coupled to the heat conducting structure to form a gap region between the heat conducting structure and the heat transfer structure, the heat transfer structure being configured to rotate during operation of the device. In example devices heat may be transferred across the gap region from a heated axial flow of the heat transfer medium to a cool stationary heat conducting structure, or from a heated stationary conducting structure to a cool axial flow of the heat transfer medium.
Inverse axial mounting stiffness design for lithographic projection lenses.
Wen-quan, Yuan; Hong-bo, Shang; Wei, Zhang
In order to balance axial mounting stiffness of lithographic projection lenses and the image quality under dynamic working conditions, an easy inverse axial mounting stiffness design method is developed in this article. Imaging quality deterioration at the wafer under different axial vibration levels is analyzed. The desired image quality can be determined according to practical requirements, and axial vibrational tolerance of each lens is solved with the damped least-squares method. Based on adaptive interval adjustment, a binary search algorithm, and the finite element method, the axial mounting stiffness of each lens can be traveled in a large interval, and converges to a moderate numerical solution which makes the axial vibrational amplitude of the lens converge to its axial vibrational tolerance. Model simulation is carried out to validate the effectiveness of the method.
Axial sesamoiditis in the horse: A review
Directory of Open Access Journals (Sweden)
Christelle Le Roux
Full Text Available Axial sesamoiditis or osteitis of the proximal sesamoid bones (PSBs in the horse is described as a rare condition. The cause remains unknown and speculative, with vascular, infectious, and traumatic aetiologies implicated. It is specifically associated with injury of the palmar or plantar ligament (PL, also known as the intersesamoidean ligament. Imaging findings are generally rewarding and radiological changes are typical, if not pathognomonic, for the condition. Lesions consist of bone lysis at the apical to mid-body axial margins of the PSBs, with variable degrees of joint effusion. Radiographic technique warrants careful attention to make a diagnosis, and exposure factors may need to be adjusted. Perineural, intra-articular and intra-thecal anaesthesia does not seem to provide consistent improvement of lameness in these cases, with literature reporting inconsistent findings. Ultrasonographic findings include digital flexor sheath effusion, loss of the normal fibre structure of the PL at its attachment to the PSBs, abnormal echogenicity or change in thickness of the PL, and irregular hyperechoic cortical margins of the axial margins of the PSBs. Scintigraphy, computed tomography and magnetic resonance imaging, although not necessary to make a diagnosis, may add valuable information regarding the location and extent of lesions. The prognosis remains guarded to poor for return to athletic function. The focus of this paper is a comprehensive review of the proposed aetiopathogenesis of the condition, the prognosis, and a summary of the literature findings with focus on the notable diagnostic imaging features, including radiography, ultrasonography, scintigraphy, computed tomography and magnetic resonance imaging.
Axial Tomography from Digitized Real Time Radiography
Zolnay, A. S.; McDonald, W. M.; Doupont, P. A.; McKinney, R. L.; Lee, M. M.
Axial tomography from digitized real time radiographs provides a useful tool for industrial radiography and tomography. The components of this system are: x-ray source, image intensifier, video camera, video line extractor and digitizer, data storage and reconstruction computers. With this system it is possible to view a two dimensional x-ray image in real time at each angle of rotation and select the tomography plane of interest by choosing which video line to digitize. The digitization of a video line requires less than a second making data acquisition relatively short. Further improvements on this system are planned and initial results are reported.
Disordered axial movement in Parkinson's disease.
Steiger, M J; Thompson, P D; Marsden, C D
Axial motor impairments are a common cause of disability in patients with Parkinson's disease, become more prominent with longer disease duration, and have been said to be less responsive to levodopa replacement therapy. The ability to turn in bed while lying supine before and after dopaminergic stimulation was studied in a group of 36 patients with Parkinson's disease; 23 were in Hoehn and Yahr stages 3-5 when "off", and 13 were in stages 1-2. Turning was also compared with postural stabilit...
Digital enhancement of computerized axial tomograms
Roberts, E., Jr.
A systematic evaluation has been conducted of certain digital image enhancement techniques performed in image space. Three types of images have been used, computer generated phantoms, tomograms of a synthetic phantom, and axial tomograms of human anatomy containing images of lesions, artificially introduced into the tomograms. Several types of smoothing, sharpening, and histogram modification have been explored. It has been concluded that the most useful enhancement techniques are a selective smoothing of singular picture elements, combined with contrast manipulation. The most useful tool in applying these techniques is the gray-scale histogram.
Axial tomography in live cell laser microscopy
Richter, Verena; Bruns, Sarah; Bruns, Thomas; Weber, Petra; Wagner, Michael; Cremer, Christoph; Schneckenburger, Herbert
Single cell microscopy in a three-dimensional (3-D) environment is reported. Cells are grown in an agarose culture gel, located within microcapillaries and observed from different sides after adaptation of an innovative device for sample rotation. Thus, z-stacks can be recorded by confocal microscopy in different directions and used for illustration in 3-D. This gives additional information, since cells or organelles that appear superimposed in one direction, may be well resolved in another one. The method is tested and validated with single cells expressing a membrane or a mitochondrially associated green fluorescent protein, or cells accumulating fluorescent quantum dots. In addition, axial tomography supports measurements of cellular uptake and distribution of the anticancer drug doxorubicin in the nucleus (2 to 6 h after incubation) or the cytoplasm (24 h). This paper discusses that upon cell rotation an enhanced optical resolution in lateral direction compared to axial direction can be utilized to obtain an improved effective 3-D resolution, which represents an important step toward super-resolution microscopy of living cells.
Axial vessel widening in arborescent monocots.
Petit, Giai; DeClerck, Fabrice A J; Carrer, Marco; Anfodillo, Tommaso
Dicotyledons have evolved a strategy to compensate for the increase in hydraulic resistance to water transport with height growth by widening xylem conduits downwards. In monocots, the accumulation of hydraulic resistance with height should be similar, but the absence of secondary growth represents a strong limitation for the maintenance of xylem hydraulic efficiency during ontogeny. The hydraulic architecture of monocots has been studied but it is unclear how monocots arrange their axial vascular structure during ontogeny to compensate for increases in height. We measured the vessel lumina and estimated the hydraulic diameter (Dh) at different heights along the stem of two arborescent monocots, Bactris gasipaes (Kunth) and Guadua angustifolia (Kunth). For the former, we also estimated the variation in Dh along the leaf rachis. Hydraulic diameter increased basally from the stem apex to the base with a scaling exponent (b) in the range of those reported for dicot trees (b = 0.22 in B. gasipaes; b = 0.31 and 0.23 in G. angustifolia). In B. gasipaes, vessels decrease in Dh from the stem's centre towards the periphery, an opposite pattern compared with dicot trees. Along the leaf rachis, a pattern of increasing Dh basally was also found (b = 0.13). The hydraulic design of the monocots studied revealed an axial pattern of xylem conduits similar to those evolved by dicots to compensate and minimize the negative effect of root-to-leaf length on hydrodynamic resistance to water flow.
Anion-π Catalysts with Axial Chirality.
Wang, Chao; Matile, Stefan
The idea of anion-π catalysis is to stabilize anionic transition states by anion-π interactions on aromatic surfaces. For asymmetric anion-π catalysis, π-acidic surfaces have been surrounded with stereogenic centers. This manuscript introduces the first anion-π catalysts that operate with axial chirality. Bifunctional catalysts with tertiary amine bases next to π-acidic naphthalenediimide planes are equipped with a bulky aromatic substituent in the imide position to produce separable atropisomers. The addition of malonic acid half thioesters to enolate acceptors is used for evaluation. In the presence of a chiral axis, the selective acceleration of the disfavored but relevant enolate addition was much better than with point chirality, and enantioselectivity could be observed for the first time for this reaction with small-molecule anion-π catalysts. Enantioselectivity increased with the π acidity of the π surface, whereas the addition of stereogenic centers around the aromatic plane did not cause further improvements. These results identify axial chirality of the active aromatic plane generated by atropisomerism as an attractive strategy for asymmetric anion-π catalysis. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.
Medullary sponge kidney on axial computed tomography
International Nuclear Information System (INIS)
Ginalski, J.-M.; Schnyder, Pierre; Portmann, Luc; Jaeger, Philippe
To evaluate features of medullary sponge kidney (MSK) on computed tomography (CT), 4-mm-thick axial slices without intravenous contrast material were 1st made in 13 patients through 24 kidneys which showed images of MSK on excretory urograms. On CT, papillary calcifications were found in 11 kidneys. In 5 of these, the calcifications were not detectable on plain films. Some hyperdense papillae (attenuation value 55-70 Hounsfield units) without calcification were found in 4 other kidneys. 9 kidneys appeared normal. 10 of the 14 kidneys were reexamined by a 2nd series of 4-mm-thick axial slices, 5 min after intravenous injection of 50 ml of Urografin. Images suggesting possible ectasia of precaliceal tubules were found in only 4 kidneys. These images appear much less obvious and characteristic on CT than on excretory urogram and do nothing more than suggest the possibility of MSK. In conclusion, the sensitivity of CT in the detection of MSK is markedly lower than that of excretory urography. In the most florid cases of the disease, CT can only show images suggesting the possibility of MSK. On the other hand, CT appears much more sensitive than plain films and tomograms of excretory in the detection of papillary calcifications, the most frequent complication of MSK. (author). 13 refs.; 3 figs
Canonical quantization of the generalized axial gauge
International Nuclear Information System (INIS)
Haller, K.
The incompatibility of the constraint A 3 =0 with canonical commutation rules is discussed. A canonical formulation is given of QED and QCD in the axial gauge with n 1 =n 2 =0, n 3 =α and n 0 =β, where α and β are arbitrary real numbers. A Hilbert space is established for the perturbative theory, and a propagator is derived by obtaining an expression for the interaction picture gauge fields, and evaluating the vacuum expectation value of its time-ordered products in the perturbative vacuum. The propagator is expressed in terms of the parameter γ=α/β and is shown to reproduce the light cone gauge propagator when γ=1, and the temporal gauge propagator when γ=0, accommodating various prescriptions for the spurious propagator pole, including the Mandelstam-Leibbrandt and principal value prescriptions. When γ→∞, the generalized axial gauge propagator leads to an expression for the propagator in the A 3 =0 gauge, though in that case the order in which the integration over k 0 is performed, and the limit γ→∞ is taken, affects the resulting expression. Another Hilbert space is established, in which the constraints that include all interactions are implemented in a time independent fashion. It is pointed out that this Hilbert space, and the Hilbert space of the perturbative theory are unitarily equivalent in QED, but that they cannot be unitarily equivalent in QCD. Implications of this fact for the nonperturbative states of QCD are discussed. (orig.)
The Modelling of Axially Translating Flexible Beams
Theodore, R. J.; Arakeri, J. H.; Ghosal, A.
The axially translating flexible beam with a prismatic joint can be modelled by using the Euler-Bernoulli beam equation together with the convective terms. In general, the method of separation of variables cannot be applied to solve this partial differential equation. In this paper, a non-dimensional form of the Euler Bernoulli beam equation is presented, obtained by using the concept of group velocity, and also the conditions under which separation of variables and assumed modes method can be used. The use of clamped-mass boundary conditions leads to a time-dependent frequency equation for the translating flexible beam. A novel method is presented for solving this time dependent frequency equation by using a differential form of the frequency equation. The assume mode/Lagrangian formulation of dynamics is employed to derive closed form equations of motion. It is shown by using Lyapunov's first method that the dynamic responses of flexural modal variables become unstable during retraction of the flexible beam, which the dynamic response during extension of the beam is stable. Numerical simulation results are presented for the uniform axial motion induced transverse vibration for a typical flexible beam.
Multi-axial response of idealized cermets
International Nuclear Information System (INIS)
Pickering, E.G.; Bele, E.; Deshpande, V.S.
The yield response of two idealized cermets comprising mono and bi-disperse steel spheres in a Sn/Pb solder matrix has been investigated for a range of axisymmetric stress states. Proportional stress path experiments are reported, from which are extracted the initial yield surfaces and their evolution with increasing plastic strain. The initial yield strength is nearly independent of the hydrostatic pressure but the strain hardening rate increases with stress triaxiality up to a critical value. For higher triaxialities, the responses are independent of hydrostatic pressure. Multi-axial measurements along with X-ray tomography were used to demonstrate that the deformation of these idealized cermets occurs by two competing mechanisms: (i) a granular flow mechanism that operates at low levels of triaxiality, where volumetric dilation occurs under compressive stress states, and (ii) a plastically incompressible mechanism that operates at high stress triaxialities. A phenomenological viscoplastic constitutive model that incorporates both deformation mechanisms is presented. While such multi-axial measurements are difficult for commercial cermets with yield strengths on the order of a few GPa, the form of their constitutive relation is expected to be similar to that of the idealized cermets presented here.
High-Definition Computed Tomography for Coronary Artery Stent Imaging: a Phantom Study
Energy Technology Data Exchange (ETDEWEB)
Yang, Wen Jie; Chen, Ke Min; Pang, Li Fang; Zhang, Huang; Pan, Zi Lai [Rui Jin Hospital, Medical School, Shanghai Jiao Tong University, Shangha (China); Guo, Ying; Li, Jian Ying [Beijing Economic and Technology Development Area, Beijing (China)
To assess the performance of a high-definition CT (HDCT) for imaging small caliber coronary stents ({<=} 3 mm) by comparing different scan modes of a conventional 64-row standard-definition CT (SDCT). A cardiac phantom with twelve stents (2.5 mm and 3.0 mm in diameter) was scanned by HDCT and SDCT. The scan modes were retrospective electrocardiography (ECG)-gated helical and prospective ECG-triggered axial with tube voltages of 120 kVp and 100 kVp, respectively. The inner stent diameters (ISD) and the in-stent attenuation value (AVin-stent) and the in-vessel extra-stent attenuation value (AVin-vessel) were measured by two observers. The artificial lumen narrowing (ALN = [ISD - ISDmeasured]/ISD) and artificial attenuation increase between in-stent and in-vessel (AAI = AVin-stent - AVin-vessel) were calculated. All data was analyzed by intraclass correlation and ANOVA-test. The correlation coefficient of ISD, AVin-vessel and AVin-stent between the two observers was good. The ALNs of HDCT were statistically lower than that of SDCT (30 {+-} 5.7% versus 35 {+-} 5.4%, p < 0.05). HDCT had statistically lower AAI values than SDCT (15.7 {+-} 81.4 HU versus 71.4 {+-} 90.5 HU, p < 0.05). The prospective axial dataset demonstrated smaller ALN than the retrospective helical dataset on both HDCT and SDCT (p < 0.05). Additionally, there were no differences in ALN between the 120 kVp and 100 kVp tube voltages on HDCT (p = 0.05). High-definition CT helps improve measurement accuracy for imaging coronary stents compared to SDCT. HDCT with 100 kVp and the prospective ECG-triggered axial technique, with a lower radiation dose than 120 kVp application, may be advantageous in evaluating coronary stents with smaller calibers ({<=} 3 mm).
Comparison of femoropopliteal artery stents under axial and radial compression, axial tension, bending, and torsion deformations.
Maleckis, Kaspars; Deegan, Paul; Poulson, William; Sievers, Cole; Desyatova, Anastasia; MacTaggart, Jason; Kamenskiy, Alexey
High failure rates of Peripheral Arterial Disease (PAD) stenting appear to be associated with the inability of certain stent designs to accommodate severe biomechanical environment of the femoropopliteal artery (FPA) that bends, twists, and axially compresses during limb flexion. Twelve Nitinol stents (Absolute Pro, Supera, Lifestent, Innova, Zilver, Smart Control, Smart Flex, EverFlex, Viabahn, Tigris, Misago, and Complete SE) were quasi-statically tested under bench-top axial and radial compression, axial tension, bending, and torsional deformations. Stents were compared in terms of force-strain behavior, stiffness, and geometrical shape under each deformation mode. Tigris was the least stiff stent under axial compression (6.6N/m axial stiffness) and bending (0.1N/m) deformations, while Smart Control was the stiffest (575.3N/m and 105.4N/m, respectively). Under radial compression Complete SE was the stiffest (892.8N/m), while Smart Control had the lowest radial stiffness (211.0N/m). Viabahn and Supera had the lowest and highest torsional stiffness (2.2μNm/° and 959.2μNm/°), respectively. None of the 12 PAD stents demonstrated superior characteristics under all deformation modes and many experienced global buckling and diameter pinching. Though it is yet to be determined which of these deformation modes might have greater clinical impact, results of the current analysis may help guide development of new stents with improved mechanical characteristics. Copyright © 2017 Elsevier Ltd. All rights reserved.
Chiral filter, axial charges and Gamow-Teller strengths
International Nuclear Information System (INIS)
Rho, M.
The different ways that nuclear matter responds to the weak axial-vector current are interpreted in terms of modification of the ''vacuum'' in baryon-rich environments. The notion of ''chiral filter'' is introduced. Use of a ward identity is suggested. The Gamow-Teller quenching and the enhanced axial charge in O + O - transitions follow from this. I also discuss briefly possible relevance of the nucleon as a topological soliton configuration to the global property of nuclear axial response functions
Isotensor Axial Polarizability and Lattice QCD Input for Nuclear Double- Decay Phenomenology
Energy Technology Data Exchange (ETDEWEB)
Shanahan, Phiala E.; Tiburzi, Brian C.; Wagman, Michael L.; Winter, Frank; Chang, Emmanuel; Davoudi, Zohreh; Detmold, William; Orginos, Kostas; Savage, Martin J.
The potential importance of short-distance nuclear effects in double-$\\beta$ decay is assessed using a lattice QCD calculation of the $nn\\rightarrow pp$ transition and effective field theory methods. At the unphysical quark masses used in the numerical computation, these effects, encoded in the isotensor axial polarisability, are found to be of similar magnitude to the nuclear modification of the single axial current, which phenomenologically is the quenching of the axial charge used in nuclear many-body calculations. This finding suggests that nuclear models for neutrinoful and neutrinoless double-$\\beta$ decays should incorporate this previously neglected contribution if they are to provide reliable guidance for next-generation neutrinoless double-$\\beta$ decay searches. The prospects of constraining the isotensor axial polarisabilities of nuclei using lattice QCD input into nuclear many-body calculations are discussed.
Geometric inequalities for axially symmetric black holes
International Nuclear Information System (INIS)
Dain, Sergio
A geometric inequality in general relativity relates quantities that have both a physical interpretation and a geometrical definition. It is well known that the parameters that characterize the Kerr-Newman black hole satisfy several important geometric inequalities. Remarkably enough, some of these inequalities also hold for dynamical black holes. This kind of inequalities play an important role in the characterization of the gravitational collapse; they are closely related with the cosmic censorship conjecture. Axially symmetric black holes are the natural candidates to study these inequalities because the quasi-local angular momentum is well defined for them. We review recent results in this subject and we also describe the main ideas behind the proofs. Finally, a list of relevant open problems is presented. (topical review)
Collimated trans-axial tomographic scintillation camera
International Nuclear Information System (INIS)
The objects of this invention are first to reduce the time required to obtain statistically significant data in trans-axial tomographic radioisotope scanning using a scintillation camera. Secondly, to provide a scintillation camera system to increase the rate of acceptance of radioactive events to contribute to the positional information obtainable from a known radiation source without sacrificing spatial resolution. Thirdly to reduce the scanning time without loss of image clarity. The system described comprises a scintillation camera detector, means for moving this in orbit about a cranial-caudal axis relative to a patient and a collimator having septa defining apertures such that gamma rays perpendicular to the axis are admitted with high spatial resolution, parallel to the axis with low resolution. The septa may be made of strips of lead. Detailed descriptions are given. (U.K.)
Collimated trans-axial tomographic scintillation camera
International Nuclear Information System (INIS)
The principal problem in trans-axial tomographic radioisotope scanning is the length of time required to obtain meaningful data. Patient movement and radioisotope migration during the scanning period can cause distortion of the image. The object of this invention is to reduce the scanning time without degrading the images obtained. A system is described in which a scintillation camera detector is moved to an orbit about the cranial-caudal axis relative to the patient. A collimator is used in which lead septa are arranged so as to admit gamma rays travelling perpendicular to this axis with high spatial resolution and those travelling in the direction of the axis with low spatial resolution, thus increasing the rate of acceptance of radioactive events to contribute to the positional information obtainable without sacrificing spatial resolution. (author)
Axial tomographic system for radiation diagnoses
International Nuclear Information System (INIS)
Crowther, T.J.
The axial tomographic scanner consists of a source of hard radiation passing a fan shaped beam through a plane layer of the body under examination, a detector, and driving systems for the sequential displacement and rotation of the radiation source and the detector. The diagnosis is made by means of a data processing system offering extensive time overlap capability of the individual system functions. The data sets from transmission or absorption are processed in three independent subsystems, i.e., the scanning system, the processing system and the display system. The systems are made up of well-known modules, e.g., Nova 1200 or Eclipse 5200. Hence, as a result of the independent design of the data system, raw data will not be lost in case of faults in some subsystem. (DG) [de
Axial grazing collisions with insulator surfaces
Energy Technology Data Exchange (ETDEWEB)
Gravielle, M.S. [Instituto de Astronomia y Fisica del Espacio (IAFE), Consejo Nacional de Investigaciones Cientificas y Tecnicas, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina) and Departamento de Fisica, FCEN, Universidad de Buenos Aires (Argentina)]. E-mail: firstname.lastname@example.com; Miraglia, J.E. [Instituto de Astronomia y Fisica del Espacio (IAFE), Consejo Nacional de Investigaciones Cientificas y Tecnicas, Casilla de Correo 67, Sucursal 28, 1428 Buenos Aires (Argentina); Departamento de Fisica, FCEN, Universidad de Buenos Aires (Argentina)
Electron capture and emission processes from insulator surfaces produced by grazing impact of fast ions are investigated under axial incidence conditions. For crystal surfaces we develop a model based on distorted wave methods, which allows us to express the coherent transition amplitude along the projectile path as a sum of atomic amplitudes, each one associated with a different lattice site. The method is applied to 100 keV protons colliding with LiF surfaces. For electron transitions from a given initial crystal state, the probabilities display strong interference effects as a function of the crystal orientation. But the interference patterns disappear when these partial probabilities are added to derive the total probability from the surface band.
Axial grazing collisions with insulator surfaces
International Nuclear Information System (INIS)
Gravielle, M.S.; Miraglia, J.E.
Electron capture and emission processes from insulator surfaces produced by grazing impact of fast ions are investigated under axial incidence conditions. For crystal surfaces we develop a model based on distorted wave methods, which allows us to express the coherent transition amplitude along the projectile path as a sum of atomic amplitudes, each one associated with a different lattice site. The method is applied to 100 keV protons colliding with LiF surfaces. For electron transitions from a given initial crystal state, the probabilities display strong interference effects as a function of the crystal orientation. But the interference patterns disappear when these partial probabilities are added to derive the total probability from the surface band
Axial nonimaging characteristics of imaging lenses: discussion.
Siew, Ronian
At observation planes away from the image plane, an imaging lens is a nonimaging optic. We examine the variation of axial irradiance with distance in image space and highlight the following little-known observation for discussion: On a per-unit-area basis, the position of the highest concentration in image space is generally not at the focal plane. This characteristic is contrary to common experience, and it offers an additional degree of freedom for the design of detection systems. Additionally, it would also apply to lenses with negative refractive index. The position of peak concentration and its irradiance is dependent upon the location and irradiance of the image. As such, this discussion also includes a close examination of expressions for image irradiance and explains how they are related to irradiance calculations beyond the image plane. This study is restricted to rotationally symmetric refractive imaging systems with incoherent extended Lambertian sources.
Aerodynamic Modelling and Optimization of Axial Fans
DEFF Research Database (Denmark)
Sørensen, Dan Nørtoft
A numerically efficient mathematical model for the aerodynamics oflow speed axial fans of the arbitrary vortex flow type has been developed.The model is based on a blade-element principle, whereby therotor is divided into a number of annular streamtubes.For each of these streamtubes relations......-Raphson method, andsolutions converged to machine accuracy are found at small computing costs.The model has been validated against published measurementson various fan configurations,comprising two rotor-only fan stages, a counter-rotatingfan unit and a stator-rotor-stator stage.Comparisons of local...... and integrated propertiesshow that the computed results agree well with the measurements.Integrating a rotor-only version of the aerodynamic modelwith an algorithm for numerical designoptimization, enables the finding of an optimum fan rotor.The angular velocity of the rotor, the hub radius and the spanwise...
Image reconstruction. Application to transverse axial tomography
International Nuclear Information System (INIS)
Aubry, Florent.
A method of computerized tridimensional image reconstruction from their projection, especially in the computerized transverse axial tomography is suggested. First, the different techniques actually developped and presented in the literature are analyzed. Then, the equipment used is briefly described. The reconstruction algorithm developped is presented. This algorithm is based on the convolution method, well adapted to the real conditions of exploitation. It is an extension of SHEPP and LOGAN's algorithm. A correction of the self absorption and of the detector's response is proposed. Finally, the first results obtained which are satisfactory are given. The simplicity of the method which does not need a too long computation time makes possible the implementation of the algorithm on a mini-computer [fr
Composite Axial Flow Propulsor for Small Aircraft
Directory of Open Access Journals (Sweden)
R. Poul
Full Text Available This work focuses on the design of an axial flow ducted fan driven by a reciprocating engine. The solution minimizes the turbulization of the flow around the aircraft. The fan has a rotor - stator configuration. Due to the need for low weight of the fan, a carbon/epoxy composite material was chosen for the blades and the driving shaft.The fan is designed for optimal isentropic efficiency and free vortex flow. A stress analysis of the rotor blade was performed using the Finite Element Method. The skin of the blade is calculated as a laminate and the foam core as a solid. A static and dynamic analysis were made. The RTM technology is compared with other technologies and is described in detail.
Estimation of ocular volume from axial length.
Nagra, Manbir; Gilmartin, Bernard; Logan, Nicola S
To determine which biometric parameters provide optimum predictive power for ocular volume. Sixty-seven adult subjects were scanned with a Siemens 3-T MRI scanner. Mean spherical error (MSE) (D) was measured with a Shin-Nippon autorefractor and a Zeiss IOLMaster used to measure (mm) axial length (AL), anterior chamber depth (ACD) and corneal radius (CR). Total ocular volume (TOV) was calculated from T2-weighted MRIs (voxel size 1.0 mm(3)) using an automatic voxel counting and shading algorithm. Each MR slice was subsequently edited manually in the axial, sagittal and coronal plane, the latter enabling location of the posterior pole of the crystalline lens and partitioning of TOV into anterior (AV) and posterior volume (PV) regions. Mean values (±SD) for MSE (D), AL (mm), ACD (mm) and CR (mm) were -2.62±3.83, 24.51±1.47, 3.55±0.34 and 7.75±0.28, respectively. Mean values (±SD) for TOV, AV and PV (mm(3)) were 8168.21±1141.86, 1099.40±139.24 and 7068.82±1134.05, respectively. TOV showed significant correlation with MSE, AL, PV (all p<0.001), CR (p=0.043) and ACD (p=0.024). Bar CR, the correlations were shown to be wholly attributable to variation in PV. Multiple linear regression indicated that the combination of AL and CR provided optimum R(2) values of 79.4% for TOV. Clinically useful estimations of ocular volume can be obtained from measurement of AL and CR. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://group.bmj.com/group/rights-licensing/permissions.
Aerodynamic modelling and optimization of axial fans
Energy Technology Data Exchange (ETDEWEB)
Noertoft Soerensen, Dan
A numerically efficient mathematical model for the aerodynamics of low speed axial fans of the arbitrary vortex flow type has been developed. The model is based on a blade-element principle, whereby the rotor is divided into a number of annular stream tubes. For each of these stream tubes relations for velocity, pressure and radial position are derived from the conservation laws for mass, tangential momentum and energy. The equations are solved using the Newton-Raphson methods, and solutions converged to machine accuracy are found at small computing costs. The model has been validated against published measurements on various fan configurations, comprising two rotor-only fan stages, a counter-rotating fan unit and a stator-rotor stator stage. Comparisons of local and integrated properties show that the computed results agree well with the measurements. Optimizations have been performed to maximize the mean value of fan efficiency in a design interval of flow rates, thus designing a fan which operates well over a range of different flow conditions. The optimization scheme was used to investigate the dependence of maximum efficiency on 1: the number of blades, 2: the width of the design interval and 3: the hub radius. The degree of freedom in the choice of design variable and constraints, combined with the design interval concept, provides a valuable design-tool for axial fans. To further investigate the use of design optimization, a model for the vortex shedding noise from the trailing edge of the blades has been incorporated into the optimization scheme. The noise emission from the blades was minimized in a flow rate design point. Optimizations were performed to investigate the dependence of the noise on 1: the number of blades, 2: a constraint imposed on efficiency and 3: the hub radius. The investigations showed, that a significant reduction of noise could be achieved, at the expense of a small reduction in fan efficiency. (EG) 66 refs.
Axially symmetric Lorentzian wormholes in general relativity
International Nuclear Information System (INIS)
Schein, F.
The field equations of Einstein's theory of general relativity, being local, do not fix the global structure of space-time. They admit topologically non-trivial solutions, including spatially closed universes and the amazing possibility of shortcuts for travel between distant regions in space and time - so-called Lorentzian wormholes. The aim of this thesis is to (mathematically) construct space-times which contain traversal wormholes connecting arbitrary distant regions of an asymptotically flat or asymptotically de Sitter universe. Since the wormhole mouths appear as two separate masses in the exterior space, space-time can at best be axially symmetric. We eliminate the non-staticity caused by the gravitational attraction of the mouths by anchoring them by strings held at infinity or, alternatively, by electric repulsion. The space-times are obtained by surgically grafting together well-known solutions of Einstein's equations along timelike hypersurfaces. This surgery naturally concentrates a non-zero stress-energy tensor on the boundary between the two space-times which can be investigated by using the standard thin shell formalism. It turns out that, when using charged black holes, the provided constructions are possible without violation of any of the energy conditions. In general, observers living in the axially symmetric, asymptotically flat (respectively asymptotically de Sitter) region axe able to send causal signals through the topologically non-trivial region. However, the wormhole space-times contain closed timelike curves. Because of this explicit violation of global hyperbolicity these models do not serve as counterexamples to known topological censorship theorems. (author)
Energy Dissipation in Sandwich Structures During Axial Compression
DEFF Research Database (Denmark)
Urban, Jesper
The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full-scale structu......The purpose of this paper is to investigate the energy dissipation in sandwich structures during axial crushing. Axial crushing tests on six sandwich elements are described. The sandwich elements consist of a polyurethane core and E-glass/Polyester skin. The elements compare to full...
Improved axial position detection in optical tweezers measurements
DEFF Research Database (Denmark)
Dreyer, Jakob Kisbye; Berg-Sørensen, Kirstine; Oddershede, Lene
We investigate the axial position detection of a trapped microsphere in an optical trap by using a quadrant photodiode. By replacing the photodiode with a CCD camera, we obtain detailed information on the light scattered by the microsphere. The correlation of the interference pattern with the axial...... position displays complex behavior with regions of positive and negative interference. By analyzing the scattered light intensity as a function of the axial position of the trapped sphere, we propose a simple method to increase the sensitivity and control the linear range of axial position detection....
Evaluation of carotid stenosis with axial high-resolution black-blood MR imaging
Energy Technology Data Exchange (ETDEWEB)
U-King-Im, Jean M.; Trivedi, Rikin A.; Sala, Evis; Graves, Martin J.; Gaskarth, Mathew; Higgins, Nicholas J.; Cross, Justin C.; Coulden, Richard A.; Antoun, Nagui M.; Gillard, Jonathan H. [University Department of Radiology, Addenbrooke' s Hospital, CB2 2QQ, Cambridge (United Kingdom); Hollingworth, William [Department of Radiology, University of Washington, 98103, Seattle, WA (United States); Kirkpatrick, Peter J. [Academic Department of Neurosurgery, Addenbrooke' s Hospital, CB2 2QQ, Cambridge (United Kingdom)
High-resolution axial black-blood MR imaging (BB MRI) has been shown to be able to characterise carotid plaque morphology. The aim of this study was to explore the accuracy of this technique in quantifying the severity of carotid stenosis. A prospective study of 54 patients with symptomatic carotid disease was conducted, comparing BB MRI to the gold standard, conventional digital subtraction X-ray angiography (DSA). The BB MRI sequence was a fast-spin echo acquisition (TE=42 ms, ETL=24, field of view = 100 x 100 mm, slice thickness = 3.0 mm) at 1.5 T using a custom-built phased-array coil. Linear measurements of luminal and outer carotid wall diameter were made directly from the axial BB MRI slices by three independent blinded readers and stenosis was calculated according to European Carotid Surgery Trial (ECST) criteria. There was good agreement between BB MRI and DSA (intraclass correlation = 0.83). Inter-observer agreement was good (average kappa = 0.77). BB MRI was accurate for detection of severe stenosis ({>=}80%) with sensitivity and specificity of 87 and 81%, respectively. Eight cases of ''DSA-defined'' moderate stenosis were overestimated as severe by BB MRI and this may be related to non-circular lumens. Axial imaging with BB MRI could potentially be used to provide useful information about severity of carotid stenosis. (orig.)
Dual-detection confocal fluorescence microscopy: fluorescence axial imaging without axial scanning.
Lee, Dong-Ryoung; Kim, Young-Duk; Gweon, Dae-Gab; Yoo, Hongki
We propose a new method for high-speed, three-dimensional (3-D) fluorescence imaging, which we refer to as dual-detection confocal fluorescence microscopy (DDCFM). In contrast to conventional beam-scanning confocal fluorescence microscopy, where the focal spot must be scanned either optically or mechanically over a sample volume to reconstruct a 3-D image, DDCFM can obtain the depth of a fluorescent emitter without depth scanning. DDCFM comprises two photodetectors, each with a pinhole of different size, in the confocal detection system. Axial information on fluorescent emitters can be measured by the axial response curve through the ratio of intensity signals. DDCFM can rapidly acquire a 3-D fluorescent image from a single two-dimensional scan with less phototoxicity and photobleaching than confocal fluorescence microscopy because no mechanical depth scans are needed. We demonstrated the feasibility of the proposed method by phantom studies.
Early brain enlargement and elevated extra-axial fluid in infants who develop autism spectrum disorder.
Shen, Mark D; Nordahl, Christine W; Young, Gregory S; Wootton-Gorges, Sandra L; Lee, Aaron; Liston, Sarah E; Harrington, Kayla R; Ozonoff, Sally; Amaral, David G
Prospective studies of infants at risk for autism spectrum disorder have provided important clues about the early behavioural symptoms of autism spectrum disorder. Diagnosis of autism spectrum disorder, however, is not currently made until at least 18 months of age. There is substantially less research on potential brain-based differences in the period between 6 and 12 months of age. Our objective in the current study was to use magnetic resonance imaging to identify any consistently observable brain anomalies in 6-9 month old infants who would later develop autism spectrum disorder. We conducted a prospective infant sibling study with longitudinal magnetic resonance imaging scans at three time points (6-9, 12-15, and 18-24 months of age), in conjunction with intensive behavioural assessments. Fifty-five infants (33 'high-risk' infants having an older sibling with autism spectrum disorder and 22 'low-risk' infants having no relatives with autism spectrum disorder) were imaged at 6-9 months; 43 of these (27 high-risk and 16 low-risk) were imaged at 12-15 months; and 42 (26 high-risk and 16 low-risk) were imaged again at 18-24 months. Infants were classified as meeting criteria for autism spectrum disorder, other developmental delays, or typical development at 24 months or later (mean age at outcome: 32.5 months). Compared with the other two groups, infants who developed autism spectrum disorder (n = 10) had significantly greater extra-axial fluid at 6-9 months, which persisted and remained elevated at 12-15 and 18-24 months. Extra-axial fluid is characterized by excessive cerebrospinal fluid in the subarachnoid space, particularly over the frontal lobes. The amount of extra-axial fluid detected as early as 6 months was predictive of more severe autism spectrum disorder symptoms at the time of outcome. Infants who developed autism spectrum disorder also had significantly larger total cerebral volumes at both 12-15 and 18-24 months of age. This is the first magnetic
Bifunctional organocatalysts for the asymmetric synthesis of axially chiral benzamides
Directory of Open Access Journals (Sweden)
Ryota Miyaji
Full Text Available Bifunctional organocatalysts bearing amino and urea functional groups in a chiral molecular skeleton were applied to the enantioselective synthesis of axially chiral benzamides via aromatic electrophilic bromination. The results demonstrate the versatility of bifunctional organocatalysts for the enantioselective construction of axially chiral compounds. Moderate to good enantioselectivities were afforded with a range of benzamide substrates. Mechanistic investigations were also carried out.
Test Setup for Axially Loaded Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina
The test setup for testing axially static and cyclic loaded piles in sand is described in the following. The purpose for the tests is to examine the tensile capacity of axially loaded piles in dense fully saturated sand. The pile dimensions are chosen to resemble full scale dimension of piles used...... in offshore pile foundations today....
Characterisation of plasmas produced by the "Torche a Injection Axiale"
Jonkers, J.; Selen, L.J.M.; Mullen, van der J.J.A.M.; Regt, de J.M.; Timmermans, E.A.H.; Schram, D.C.
Summary form only given. The Torche a Injection Axiale (TIA), i.e. torch with axial gas injection, was developed by the group of Moisan in 1993. We report on the investigations on two different kind of plasmas created by the TIA: one with helium and the other with argon as main gas. Using absolute
Equation of motion for the axial gravitational superfield
International Nuclear Information System (INIS)
Ogievetsky, V.; Sokatchev, E.
Transformation properties of the axial supergravitational field variants are investigated. The equation of motion for the axial gravitational superfield is derived by direct variation of the N = 1 supergravity action. The left-hand side of this equation is a component of the torsion tensor, and the right-hand side is the supercurrent. The question about the cosmological term in supergravity is discussed
Original paper Cytokine profiles in axial spondyloarthritis
Directory of Open Access Journals (Sweden)
Marta Madej
Full Text Available Objectives: Current studies concentrate on the cytokine network and its role in the pathogenesis of spondyloarthritis (SpA. In this study, we analyzed whether the serum cytokine profile (interleukins: IL-10, IL-11, IL-12, IL-15, IL-17, IL-23 and IL-33 correlates with demographic data, clinical manifestations, disease activity and treatment outcome in a group of patients with axial spondyloarthritis. Material and methods: Forty-nine patients with an established diagnosis of axial spondyloarthritis (aSpA and 19 healthy volunteers as controls were enrolled in the study. Clinical evaluation included patient's medical history, 44 joint count, back pain intensity and global disease activity in the preceding week (VAS, the duration of morning stiffness and blood tests. Disease activity was assessed using BASDAI and ASDAS-CRP. Serum concentration of IL-10, IL-11, IL-12, IL-15, IL-17, IL-23 and IL-33 was determined. Results : In patients with aSpA, elevated serum concentration of IL-10, IL-15, IL-17 and IL-23 was detected. In the aSpA group we detected higher values of serum concentration of IL-23 and IL-33 in the subgroup with anterior uveitis (83.1 ±184.0 pg/ml vs. 14.0 ±17.1 pg/ml, p < 0.0001 and 45.5 ±71.9 pg/ml vs. 18.4 ±14.3 pg/ml, p < 0.0001, respectively. Additionally, in the subgroup with peripheral arthritis, elevation of serum concentration of IL-12 (249.3 ±246.9 pg/ml vs. 99.9 ±105.9 pg/ml, p = 0.0001 was detected. Patients with preradiological SpA had higher serum concentration of IL-17 than patients with established diagnosis of AS (6.37 ±8.50 pg/ml vs. 2.04 ±2.98 pg/ml, p = 0.0295. No differences in serum concentration of analyzed cytokines were found between the subgroup with low to moderate disease activity and the subgroup with high to very high disease activity. Conclusions : We report that in aSpA patients, compared to controls, elevated serum concentrations of IL-10, IL-15, IL-17 and IL-23 were observed. Some cytokines may
The Klinger hot gas double axial valve
International Nuclear Information System (INIS)
Kruschik, J.; Hiltgen, H.
The Klinger hot gas valve is a medium controlled double axial valve with advanced design features and safety function. It was first proposed by Klinger early in 1976 for the PNP-Project as a containment shut-off for hot helium (918 deg. C and 42 bar), because a market research has shown that such a valve is not state of present techniques. In the first stage of development a feasibility study had to be made by detailed design, calculation and by basic experiments for key components in close collaboration with Interatom/GHT. This was the basis for further design, calculation, construction and experimental work for such a valve prototype within the new development contract. The stage of knowledge to that time revealed the following key priority development areas: Finite element stress analysis for the highly stressed high temperature main components; development of an insulation layout; Detailed experimental tests of functionally important structural components or units of the valve, partly at Klingers (gasstatic bearings, flexible metallic sealing element, aerodynamic and thermohydraulic tests), partly at Interatom (actuator unit and also gasstatic bearings), partly at HRB in Juelich (flexible metallic sealing system, aerodynamic and thermohydraulic tests); Design of a test valve for experimental work in the KVK (test circuit at Interatom) for evaluation of temperature distribution and reliability of operation; Design of a prototype and extensive testing in the KVK
Small axial compressor technology, volume 1
Holman, F. F.; Kidwell, J. R.; Ware, T. C.
A scaled single-stage, highly-loaded, axial-flow transonic compressor was tested at speeds from 70 to 110% design equivalent speed to evaluate the effects of scaling compromises and the individual and combined effects of rotor tip running clearance and rotor shroud casing treatment on the overall and blade element performance. At design speed and 1% tip clearance the stage demonstrated an efficiency of 83.2% at 96.4% design flow and a pressure ratio of 1.865. Casing treatment increased design speed surge margin 2.0 points to 12.8%. Overall performance was essentially unchanged. An increase in rotor running clearance to 2.2%, with smooth casing, reduced design speed peak efficiency 5.7 points, flow by 7.4%, pressure ratio to 1.740, and surge margin to 5.4%. Reinstalling casing treatment regained 3.5 points in design speed peak efficiency, 4.7% flow, increased pressure ratio to 1.800 and surge margin to 8.7%.
Giant Cell Tumors of the Axial Skeleton
Directory of Open Access Journals (Sweden)
Maurice Balke
Full Text Available Background. We report on 19 cases of giant cell tumor of bone (GCT affecting the spine or sacrum and evaluate the outcome of different treatment modalities. Methods. Nineteen patients with GCT of the spine (=6 or sacrum (=13 have been included in this study. The mean followup was 51.6 months. Ten sacral GCT were treated by intralesional procedures of which 4 also received embolization, and 3 with irradiation only. All spinal GCT were surgically treated. Results. Two (15.4% patients with sacral and 4 (66.7% with spinal tumors had a local recurrence, two of the letter developed pulmonary metastases. One local recurrence of the spine was successfully treated by serial arterial embolization, a procedure previously described only for sacral tumors. At last followup, 9 patients had no evidence of disease, 8 had stable disease, 1 had progressive disease, 1 died due to disease. Six patients had neurological deficits. Conclusions. GCT of the axial skeleton have a high local recurrence rate. Neurological deficits are common. En-bloc spondylectomy combined with embolization is the treatment of choice. In case of inoperability, serial arterial embolization seems to be an alternative not only for sacral but also for spinal tumors.
Axial channeling of boron ions into silicon
International Nuclear Information System (INIS)
La Ferla, A.; Galvagno, G.; Raineri, V.; Setola, R.; Rimini, E.; Carnera, A.; Gasparotto, A.
Channeling boron implants were performed into (100) and (110) silicon substrates in the energy range 80-700 keV. The dose ranged between 3.5x10 11 and 1x10 15 atoms/cm 2 . The axial channeling concentration profiles of implanted B + were compared with that obtained for incidence along the random direction of the crystal and with that obtained by implantation in amorphous silicon. The electrical and chemical boron distributions were obtained by spreading resistance and secondary ion mass spectrometry measurements, respectively. The inelastic stopping power, S c , was extracted from the experimental maximum ranges for the [100] and [110] axis. The energy dependence of the electronic stopping power is given by S e = KE p with p [100] = 0.469±0.010 and p [110] = 0.554±0.004. Simulations obtained by the MARLOWE code, using the Oen-Robinson impact parameter dependent formula, for the electronic energy loss reproduce quite well the experimental depth profiles. (orig.)
Axial sheath dynamics in a plasma focus
International Nuclear Information System (INIS)
Soliman, H.M.; El-Khalafawy, T.A.; Masoud, M.M.
This paper presents the result of investigation with a 10 kJ Mather type plasma focus. It is operated in hydrogen gas at ambient pressure of 0.15--1 torr and charging voltage of 8--11 kV. Radial distribution of the current sheath density with axial distance has been estimated. Plasma rotation in the expansion chamber in the absence of external magnetic field has been detected. A plasma flare from the plasma focus region propagating in the radial direction has been observed. Streak photography shows two plasma streams flowing simultaneously out of the muzzle. The mean energy of the electron beam ejected from the pinch region of the focused plasma, was measured by retarding field analyzer to be 0.32 keV. The electron temperature of the plasma focus at peak compression was determined by measuring the X-ray intensity as a function of absorber thickness at a distance of 62 cm from the focus. The electron temperature has been found to 3 keV
Relation between axial length and ocular parameters
Directory of Open Access Journals (Sweden)
Xue-Qiu Yang
Full Text Available AIM: To investigatethe relation between axial length(AL, age and ocular parameters.METHODS: A total of 360 subjects(360 eyeswith emmetropia or myopia were recruited. Refraction, center corneal thickness(CCT, AL, intraocular pressure(IOPwere measured by automatic-refractor, Pachymeter, A-mode ultrasound and non-contact tonometer, respectively. Corneal curvature(CC, anterior chamber depth(ACDand white-to-white distance(WWDwere measured by Orbscan II. Three dimensional frequency domain coherent optical tomography(3D-OCTwas used to examine the retinal nerve fiber layer thickness(RNFLT. The Pearson correlation coefficient(rand multiple regression analysis were performed to evaluate the relationship between AL, age and ocular parameters.RESULTS: The average AL was 24.15±1.26mm. With elongation of the AL, spherical equivalent(SE(r=-0.742,Pr=-0.395, Pr=-0.374, Pr=0.411, Pr=0.099, P=0.060and WWD(r=0.061, P=0.252. There was also a significant correlation between AL and age(P=0.001, SE(PPPCONCLUSION: In longer eyes, there is a tendency toward myopia, a flatter cornea, a deeper ACD and a thinner RNFLT. Age is an influencing factor for the AL as well.
Analysis of SONACO axial cooling experiments
International Nuclear Information System (INIS)
Sigg, B.; Dury, T.V.; Hudina, M.
The SONACO test rig contained a sodium-cooled, electrically heated 37-pin bundle. On this rig, a series of forced, mixed and natural convection experiments have been performed with the aim of contributing to the understanding of thermal-hydraulic phenomena and providing data for code validation for a subassembly at decay heat power level with low flow or stagnant coolant. The test section and especially the heater pins were equipped with an extensive number of chromel-alumel thermocouples. In addition, special permanent-magnet probes were used for measuring local velocities. In this paper we give a survey of results from axial cooling experiments, where heat was removed by natural convection to a cooling coil situated in the coolant channel (plenum) above the bundle. The experimental conditions led to turbulent convection with a slowly varying, large scale flow pattern. It is shown that a power tilt in the bundle reduces these fluctuations but does not eliminate them. For the uniformly heated bundle, aglebraic expressions for the average turbulent heat flux as well as for temperature and velocity fluctuations are derived from a second-moments model and compared with experimental data. Furthermore, heat transfer in the plenum and the consequences of the SONACO experiments for the coolability of reactor fuel elements under loss-of-flow conditions are discussed. ((orig.))
Nucleon axial coupling from Lattice QCD
Cheng Chang, Chia; Nicholson, Amy; Rinaldi, Enrico; Berkowitz, Evan; Garron, Nicolas; Brantley, David; Monge-Camacho, Henry; Monahan, Chris; Bouchard, Chris; Clark, M. A.; Joó, Bálint; Kurth, Thorsten; Orginos, Kostas; Vranas, Pavlos; Walker-Loud, André
We present state-of-the-art results from a lattice QCD calculation of the nucleon axial coupling, gA, using Möbius Domain-Wall fermions solved on the dynamical Nf = 2 + 1 + 1 HISQ ensembles after they are smeared using the gradient-flow algorithm. Relevant three-point correlation functions are calculated using a method inspired by the Feynman-Hellmann theorem, and demonstrate significant improvement in signal for fixed stochastic samples. The calculation is performed at five pion masses of mπ {400, 350, 310, 220, 130} MeV, three lattice spacings of a {0.15, 0.12, 0.09} fm, and we do a dedicated volume study with mπL {3.22, 4.29, 5.36}. Control over all relevant sources of systematic uncertainty are demonstrated and quantified. We achieve a preliminary value of gA = 1.285(17), with a relative uncertainty of 1.33%.
Multimode interaction in axially excited cylindrical shells
Directory of Open Access Journals (Sweden)
Silva F. M. A.
Full Text Available Cylindrical shells exhibit a dense frequency spectrum, especially near the lowest frequency range. In addition, due to the circumferential symmetry, frequencies occur in pairs. So, in the vicinity of the lowest natural frequencies, several equal or nearly equal frequencies may occur, leading to a complex dynamic behavior. So, the aim of the present work is to investigate the dynamic behavior and stability of cylindrical shells under axial forcing with multiple equal or nearly equal natural frequencies. The shell is modelled using the Donnell nonlinear shallow shell theory and the discretized equations of motion are obtained by applying the Galerkin method. For this, a modal solution that takes into account the modal interaction among the relevant modes and the influence of their companion modes (modes with rotational symmetry, which satisfies the boundary and continuity conditions of the shell, is derived. Special attention is given to the 1:1:1:1 internal resonance (four interacting modes. Solving numerically the governing equations of motion and using several tools of nonlinear dynamics, a detailed parametric analysis is conducted to clarify the influence of the internal resonances on the bifurcations, stability boundaries, nonlinear vibration modes and basins of attraction of the structure.
Stall inception and warning in a single-stage transonic axial compressor with axial skewed slot casing treatment
International Nuclear Information System (INIS)
Lim, Byeung Jun; Kwon, Se Jin; Park, Tae Choon
Characteristic changes in the stall inception in a single-stage transonic axial compressor with an axial skewed slot casing treatment were investigated experimentally. A rotating stall occurred intermittently in a compressor with an axial skewed slot, whereas spike-type rotating stalls occurred in the case of smooth casing. The axial skewed slot suppressed stall cell growth and increased the operating range. A mild surge, the frequency of which is the Helmholtz frequency of the compressor system, occurred with the rotating stall. The irregularity in the pressure signals at the slot bottom increased decreasing flow rate. An autocorrelation-based stall warning method was applied to the measured pressure signals. Results estimate and warn against the stall margin in a compressor with an axial skewed slot.
Conservative axial burnup distributions for actinide-only burnup credit
International Nuclear Information System (INIS)
Kang, C.; Lancaster, D.
Unlike the fresh fuel approach, which assumes the initial isotopic compositions for criticality analyses, any burnup credit methodology must address the proper treatment of axial burnup distributions. A straightforward way of treating a given axial burnup distribution is to segment the fuel assembly into multiple meshes and to model each burnup mesh with the corresponding isotopic compositions. Although this approach represents a significant increase in modeling efforts compared to the uniform average burnup approach, it can adequately determine the reactivity effect of the axial burnup distribution. A major consideration is what axial burnup distributions are appropriate for use in light of many possible distributions depending on core operating conditions and histories. This paper summarizes criticality analyses performed to determine conservative axial burnup distributions. The conservative axial burnup distributions presented in this paper are included in the Topical Report on Actinide-Only Burnup Credit for Pressurized Water Reactor Spent Nuclear Fuel Packages, Revision 1 submitted in May 1997 by the US Department of Energy (DOE) to the US Nuclear Regulatory Commission (NRC). When approved by NRC, the conservative axial burnup distributions may be used to model PWR spent nuclear fuel for the purpose of gaining actinide only burnup credit
Axial currents and nuclear spin orientation
International Nuclear Information System (INIS)
Minamisono, T.; Nojiri, Y.; Matsuta, K.
This paper discusses the symmetries in the phenomena in which weak interaction is involved are largely violated, and it is still the up-to-date fore-front to study the structure of the nuclear weak currents and to learn the limitations on the applicabilities of the various relevant conservation laws as well as the nuclear structures studied by the β-decay. In this meeting, research works on the β-decay processes for the past 10 years have focused on the recoil order experiments designed to determine the limits of validity of the conserved vector current (CVC) theory and to test the G parity conservation i.e. the search for the second class currents (SCC), as well as to study the structure of the axial currents. Concerning the SCC, after intensive studies, but with not conclusive results, on the ft values of mirror β-decays in the early seventies, the correlation-type measurements on mass A=8, 12, 19 and 20 systems have been also carried out in various laboratories from 1975. Among those, concerns have been with the mass A=12 nuclear triad, /sup 12/B-/sup 12/C-/sup 12/N, the energy diagram of which is well known. The choice of this triad is because of the test done for the strong CVC predictions using the spectrum shapes of β-rays combined with the experimental analogue γ-width in /sup 12/C as well as those relevant nuclear structures. Thus, this A=12 system provides the best testing ground for the research described above
Axial displacements in external and internal implant-abutment connection.
Lee, Ji-Hye; Kim, Dae-Gon; Park, Chan-Jin; Cho, Lee-Ra
The purpose of this study was to evaluate the axial displacement of the abutments during clinical procedures by the tightening torque and cyclic loading. Two different implant-abutment connection systems were used (external butt joint connection [EXT]; internal tapered conical connection [INT]). The master casts with two implant replicas, angulated 10° from each other, were fabricated for each implant connection system. Four types of impression copings were assembled and tightened with the corresponding implants (hex transfer impression coping, non-hex transfer impression coping, hex pick-up impression coping, non-hex pick-up impression coping). Resin splinted abutments and final prosthesis were assembled. The axial displacement was measured from the length of each assembly, which was evaluated repeatedly, after 30 Ncm torque tightening. After 250 N cyclic loading of final prosthesis for 1,000,000 cycles, additional axial displacement was recorded. The mean axial displacement was statistically analyzed (repeated measured ANOVA). There was more axial displacement in the INT group than that of the EXT group in impression copings, resin splinted abutments, and final prosthesis. Less axial displacement was found at 1-piece non-hex transfer type impression coping than other type of impression copings in the INT group. There was more axial displacement at the final prosthesis than resin splinted abutments in the INT and the EXT groups. After 250 N cyclic loading of final prosthesis, the INT group showed more axial displacement than that of the EXT group. Internal tapered conical connection demonstrated a varying amount of axial displacement with tightening torque and cyclic loading. © 2012 John Wiley & Sons A/S. Published by Blackwell Publishing Ltd.
Radial loads and axial thrusts on centrifugal pumps
International Nuclear Information System (INIS)
The proceedings of a seminar organised by the Power Industries Division of the IMechE are presented in this text. Complete contents: Review of parameters influencing hydraulic forces on centrifugal impellers; The effect of fluid forces at various operation conditions on the vibrations of vertical turbine pumps; A review of the pump rotor axial equilibrium problem - some case studies; Dynamic hydraulic loading on a centrifugal pump impeller; Experimental research on axial thrust loads of double suction centrifugal pumps; A comparison of pressure distribution and radial loads on centrifugal pumps; A theoretical and experimental investigation of axial thrusts within a multi-stage centrifugal pump
Measurement for cobalt target activity and its axial distribution
International Nuclear Information System (INIS)
Li Xingyuan; Chen Zigen.
Cobalt target activity and its axial distribution are measured in process of producing radioactive isotopes 60 Co by irradiation in HFETR. Cobalt target activity is obtained with measured data at 3.60 m and 4.60 m, relative axial distribution of cobalt target activity is obtained with one at 30 cm, and axial distribution of cobalt target activity(or specific activity) is obtained with both of data. The difference between this specific activity and measured result for 60 Co teletherapy sources in the end is less than +- 5%
Gravitational waves from the axial perturbations of hyperon stars
International Nuclear Information System (INIS)
Wen De-Hua; Yan Jing; Liu Xue-Mei
The eigen-frequencies of the axial w-mode oscillations of hyperon stars are examined. It is shown that as the appearance of hyperons softens the equation of state of the super-density matter, the frequency of gravitational waves from the axial w-mode of hyperon star becomes smaller than that of a traditional neutron star at the same stellar mass. Moreover, the eigenfrequencies of hyperon stars also have scaling universality. It is shown that the EURO third-generation gravitational-wave detector has the potential to detect the gravitational-wave signal emitted from the axial w-mode oscillations of a hyperon star. (general)
Axial weak currents in the Wess-Zumino term
International Nuclear Information System (INIS)
Fujikawa, Kazuo.
The conventional axial gauging of the Wess-Zumino term leads to the results which do not necessarily agree with the expectations on the basis of quark level Ward-Takahashi identities. This discrepancy arises from the fact that the quark level anomalous identities reflect the short distance structure of QCD, whereas the gauging of the Wess-Zumino term reflects the axial symmetry in the spontaneously broken chiral phase. The low energy theorem for axial weak fields is not sharply defined, in contrast to the case of vector fields where no such complications arise. (author)
Pion Photo- and Electroproduction and the Partially Conserved Axial Current
International Nuclear Information System (INIS)
Haberzettl, Helmut
The relevance of the axial current for pion production processes off the nucleon with real or virtual photons is revisited. Employing the hypothesis of a partially conserved axial current (PCAC), it is shown that, when all of the relevant contributions are taken into account, PCAC does not provide any additional constraint for threshold production processes that goes beyond the Goldberger-Treiman relation. In particular, it is shown that pion electroproduction processes at threshold cannot be used to extract any information regarding the weak axial form factor. The relationships found in previous investigations are seen to be an accident of the approximations usually made in this context
The spin of the proton and the axial anomaly
International Nuclear Information System (INIS)
Hatsuda, T.; Zahed, I.
We show that a consistent treatment of the abelian axial anomaly in a two-phase model of the proton yields a flavor singlet axial current that is saturated by the anomaly at Q 2 =0 in the chiral limit. This result suggests that at Q 2 =0 the matrix element of the flavor singlet axial current in a polarized proton state is small while the proton spin is still one-half. Modulo the QCD evolution equation, this result is in fair agreement with the recent EMC data. (orig.)
The Design Method of Axial Flow Runners Focusing on Axial Flow Velocity Uniformization and Its Application to an Ultra-Small Axial Flow Hydraulic Turbine
Directory of Open Access Journals (Sweden)
Yasuyuki Nishi
Full Text Available We proposed a portable and ultra-small axial flow hydraulic turbine that can generate electric power comparatively easily using the low head of open channels such as existing pipe conduits or small rivers. In addition, we proposed a simple design method for axial flow runners in combination with the conventional one-dimensional design method and the design method of axial flow velocity uniformization, with the support of three-dimensional flow analysis. Applying our design method to the runner of an ultra-small axial flow hydraulic turbine, the performance and internal flow of the designed runner were investigated using CFD analysis and experiment (performance test and PIV measurement. As a result, the runners designed with our design method were significantly improved in turbine efficiency compared to the original runner. Specifically, in the experiment, a new design of the runner achieved a turbine efficiency of 0.768. This reason was that the axial component of absolute velocity of the new design of the runner was relatively uniform at the runner outlet in comparison with that of the original runner, and as a result, the negative rotational flow was improved. Thus, the validity of our design method has been verified.
Transitions in axial morphology along the Southeast Indian Ridge
Ma, Ying; Cochran, James R.
Shipboard bathymetric and magnetic profiles across the Southeast Indian Ridge (SEIR) were analyzed in order to examine the nature of along-axis variations in axial morphology at this intermediate spreading rate ridge. Three types of axial morphology are observed along the SEIR: an axial high, a shallow (200-700 m deep) axial valley and a deep (>1000 m deep) axial valley. An axial high is found to the east of the Australian-Antarctic Discordance (AAD) (east of 128°E) and between 82°E and 104°E. A shallow rift valley is found from 104°E to 114°E and from 82°E westward past the Amerstdam/St. Paul hotspot (ASP) to about 30°S, 75°E. Deep rift valleys are found from 114°E to 128°E in the vicinity of the AAD and from the Indian Ocean Triple Junction (IOTJ) at 25°S, 70°E to about 30°S, 75°E. The transition near 30°S occurs in an area of constant zero-age depth and does not appear to result from an increase in mantle temperature. It could be the result of the rapid increase in spreading rate along that portion of the SEIR. The most likely cause of the other transitions in axial morphology is variations in mantle temperature. The transitions between the different types of axial morphology are well defined and occur over a limited distance. Transitions in axial morphology are accompanied by significant changes in ridge flank topographic roughness. The transitions from axial valleys to axial highs are also accompanied by changes in the amplitude of the seafloor magnetic anomalies. Our observations suggest that there are distinct modes rather than a continuum of axial morphology on the SEIR and that there appears to be a "threshold" mechanism for a rapid change between different states of axial morphology. The ASP has only a limited influence on the SEIR. The ridge axis is marked by an axial valley for the entire distance from the IOTJ up to and past the ASP. The ridge axis becomes shallower as the ASP is approached from the northwest but only by about 300 m over
African Journals Online (AJOL)
Aug 1, 2003 ... Conclusion: Our study has demonstrated comparative variations in means and ranges of normal axial angles .... population was significantly different from the mean ... case, however, the angle also exhibits racial variations.
Three-dimensional magnetotelluric axial anisotropic forward modeling and inversion
Cao, Hui; Wang, Kunpeng; Wang, Tao; Hua, Boguang
Magnetotelluric (MT) data has been widely used to image underground electrical structural. However, when the significant axial resistivity anisotropy presents, how this influences three-dimensional MT data has not been resolved clearly yet. We here propose a scheme for three-dimensional modeling of MT data in presence of axial anisotropic resistivity, where the electromagnetic fields are decomposed into primary and secondary components. A 3D staggered-grid finite difference method is then used to resolve the resulting 3D governing equations. Numerical tests have completed to validate the correctness and accuracy of the present algorithm. A limited-memory Broyden-Fletcher-Goldfarb-Shanno method is then utilized to realize the 3D MT axial anisotropic inversion. The testing results show that, compared to the results of isotropic resistivity inversion, taking account the axial anisotropy can much improve the inverted results.
The geometrical theory of diffraction for axially symmetric reflectors
DEFF Research Database (Denmark)
Rusch, W.; Sørensen, O.
The geometrical theory of diffraction (GTD) (cf. [1], for example) may be applied advantageously to many axially symmetric reflector antenna geometries. The material in this communication presents analytical, computational, and experimental results for commonly encountered reflector geometries...
Effect of axial heat flux distribution on CHF
Energy Technology Data Exchange (ETDEWEB)
Park, Cheol
Previous investigations for the effect of axial heat flux distributions on CHF and the prediction methods are reviewed and summarized. A total of 856 CHF data in a tube with a non-uniform axial heat flux distribution has been compiled from the articles and analyzed using the 1995 Groeneveld look-up table. The results showed that two representative correction factors, K5 of the look-up table and Tongs F factor, can be applied to describe the axial heat flux distribution effect on CHF. However, they overpredict slightly the measured CHF, depending on the quality and flux peak shape. Hence, a corrected K5 factor, which accounts for the axial heat flux distribution effect is suggested to correct these trends. It predicted the CHF power for the compiled data with an average error of 1.5% and a standard deviation of 10.3%, and also provides a reasonable prediction of CHF locations.
The relation between anomalous magnetic moment and axial anomaly
International Nuclear Information System (INIS)
Teryaev, O.V.
The conservation of total angular momentum of spinor particle leads to a simple relation between the famous Schwinger and Adler coefficients determining axial anomaly and anomalous magnetic moment, respectively. (author). 8 refs, 1 fig
Report on the Dynamical Evolution of an Axially Symmetric Quasar ...
Indian Academy of Sciences (India)
retical arguments together with some numerical evidence. The evolution of the orbits is studied, as mass is transported from the disk to the nucleus. ... galaxies and non-axially symmetric quasar models (see Papadopoulos & Caranicolas.
Axial clamp for nuclear reactor head penetration conoseal joints
International Nuclear Information System (INIS)
Hackley, T.A.
A method for forming a sealed coupling between two bodies each body presenting an abutment surface, the bodies being arranged so that their respective abutment surfaces are axially adjacent one another and define a space therebetween in which a deformable gasket is disposed. An axial external force is applied to the bodies for compressing the abutment surfaces together against the gasket to form a seal between the bodies and the bodies are immobilized relative to one another while the external force is being applied to the bodies so that sufficient compression will be maintained by the abutment surfaces to preserve the integrity of the seal when the external axial force is withdrawn. The external axial force is then withdrawn, leaving the two bodies coupled together via the seal. (author)
first principles derivation of a stress function for axially symmetric
African Journals Online (AJOL)
governing partial differential equations of linear isotropic elasticity were reduced to the solution of the biharmonic ... The stress function was then applied to solve the axially symmetric ..... [1] Borg S.K.: Fundamentals of Engineering Elasticity,.
Cladding axial elongation models for FRAP-T6
International Nuclear Information System (INIS)
Shah, V.N.; Carlson, E.R.; Berna, G.A.
This paper presents a description of the cladding axial elongation models developed at the Idaho National Engineering Laboratory (INEL) for use by the FRAP-T6 computer code in analyzing the response of fuel rods during reactor transients in light water reactors (LWR). The FRAP-T6 code contains models (FRACAS-II subcode) that analyze the structural response of a fuel rod including pellet-cladding-mechanical-interaction (PCMI). Recently, four models were incorporated into FRACAS-II to calculate cladding axial deformation: (a) axial PCMI, (b) trapped fuel stack, (c) fuel relocation, and (d) effective fuel thermal expansion. Comparisons of cladding axial elongation measurements from two experiments with the corresponding FRAP-T6 calculations are presented
Uniform Decay for Solutions of an Axially Moving Viscoelastic Beam
Energy Technology Data Exchange (ETDEWEB)
Kelleche, Abdelkarim, E-mail: firstname.lastname@example.com [Université des Sciences et de la Technologie Houari Boumediene, Faculté des Mathématiques (Algeria); Tatar, Nasser-eddine, E-mail: firstname.lastname@example.com [King Fahd University of Petroleum and Minerals, Department of Mathematics and Statistics (Saudi Arabia)
The paper deals with an axially moving viscoelastic structure modeled as an Euler–Bernoulli beam. The aim is to suppress the transversal displacement (transversal vibrations) that occur during the axial motion of the beam. It is assumed that the beam is moving with a constant axial speed and it is subject to a nonlinear force at the right boundary. We prove that when the axial speed of the beam is smaller than a critical value, the dissipation produced by the viscoelastic material is sufficient to suppress the transversal vibrations. It is shown that the rate of decay of the energy depends on the kernel which arise in the viscoelastic term. We consider a general kernel and notice that solutions cannot decay faster than the kernel.
Axially modulated arch resonator for logic and memory applications
Hafiz, Md Abdullah Al; Tella, Sherif Adekunle; Alcheikh, Nouha; Fariborzi, Hossein; Younis, Mohammad I.
We demonstrate reconfigurable logic and random access memory devices based on an axially modulated clamped-guided arch resonator. The device is electrostatically actuated and the motional signal is capacitively sensed, while the resonance frequency
Quasi-renormalization of the axial vector model
International Nuclear Information System (INIS)
Schweda, M.
Using the regulator-free BPHZL renormalization scheme the problem of anomalies in a massive axial vector meson model is reinvestigated. The Adler-Bardeen-Bell-Jackiw anomaly introduces some impressive modifications: the nontrivial self-energy and the counterterm of the longitudinal part of the axial vector field depend on the anomaly via the anomalous Ward identity. The investigations are based on a Fermi-type gauge. (author)
Directory of Open Access Journals (Sweden)
Cătălin IANCU
Full Text Available In this paperwork is presented the modeling strategy used in SOLIDWORKS for modeling special items as large axial bearing and the steps to be taken in order to obtain a better design. In the paper are presented the features that are used for modeling parts, and then the steps that must be taken in order to obtain the 3D model of a large axial bearing used for bucket-wheel equipment for charcoal moving.
The research on flow pulsation characteristics of axial piston pump
Wang, Bingchao; Wang, Yulin
The flow pulsation is an important factor influencing the axial piston pump performance. In this paper we implement modeling and simulation of the axial piston pump with AMESim software to explore the flow pulsation characteristics under various factors . Theory analysis shows the loading pressure, angular speed, piston numbers and the accumulator impose evident influence on the flow pulsation characteristics. This simulation and analysis can be used for reducing the flow pulsation rate via properly setting the related factors.
Development of vortex model with realistic axial velocity distribution
International Nuclear Information System (INIS)
Ito, Kei; Ezure, Toshiki; Ohshima, Hiroyuki
A vortex is considered as one of significant phenomena which may cause gas entrainment (GE) and/or vortex cavitation in sodium-cooled fast reactors. In our past studies, the vortex is assumed to be approximated by the well-known Burgers vortex model. However, the Burgers vortex model has a simple but unreal assumption that the axial velocity component is horizontally constant, while in real the free surface vortex has the axial velocity distribution which shows large gradient in radial direction near the vortex center. In this study, a new vortex model with realistic axial velocity distribution is proposed. This model is derived from the steady axisymmetric Navier-Stokes equation as well as the Burgers vortex model, but the realistic axial velocity distribution in radial direction is considered, which is defined to be zero at the vortex center and to approach asymptotically to zero at infinity. As the verification, the new vortex model is applied to the evaluation of a simple vortex experiment, and shows good agreements with the experimental data in terms of the circumferential velocity distribution and the free surface shape. In addition, it is confirmed that the Burgers vortex model fails to calculate accurate velocity distribution with the assumption of uniform axial velocity. However, the calculation accuracy of the Burgers vortex model can be enhanced close to that of the new vortex model in consideration of the effective axial velocity which is calculated as the average value only in the vicinity of the vortex center. (author)
Reactive control of subsonic axial fan noise in a duct.
Liu, Y; Choy, Y S; Huang, L; Cheng, L
Suppressing the ducted fan noise at low frequencies without varying the flow capacity is still a technical challenge. This study examines a conceived device consisting of two tensioned membranes backed with cavities housing the axial fan for suppression of the sound radiation from the axial fan directly. The noise suppression is achieved by destructive interference between the sound fields from the axial fan of a dipole nature and sound radiation from the membrane via vibroacoustics coupling. A two-dimensional model with the flow effect is presented which allows the performance of the device to be explored analytically. The air flow influences the symmetrical behavior and excites the odd in vacuo mode response of the membrane due to kinematic coupling. Such an asymmetrical effect can be compromised with off-center alignment of the axial fan. Tension plays an important role to sustain the performance to revoke the deformation of the membrane during the axial fan operation. With the design of four appropriately tensioned membranes covered by a cylindrical cavity, the first and second blade passage frequencies of the axial fan can be reduced by at least 20 dB. The satisfactory agreement between experiment and theory demonstrates that its feasibility is practical.
Investigation of angular and axial smoothing of PET data
International Nuclear Information System (INIS)
Daube-Witherspoon, M.E.; Carson, R.E.
Radial filtering of emission and transmission data is routinely performed in PET during reconstruction in order to reduce image noise. Angular smoothing is not typically done, due to the introduction of a non-uniform resolution loss; axial filtering is also not usually performed on data acquired in 2D mode. The goal of this paper was to assess the effects of angular and axial smoothing on noise and resolution. Angular and axial smoothing was incorporated into the reconstruction process on the Scanditronix PC2048-15B brain PET scanner. In-plane spatial resolution and noise reduction were measured for different amounts of radial and angular smoothing. For radial positions away from the center of the scanner, noise reduction and degraded tangential resolution with no loss of radial resolution were seen. Near the center, no resolution loss was observed, but there was also no reduction in noise for angular filters up to a 7 degrees FWHM. These results can be understood by considering the combined effects of smoothing projections across rows (angles) and then summing (backprojecting). Thus, angular smoothing is not optimal due to its anisotropic noise reduction and resolution degradation properties. However, uniform noise reduction comparable to that seen with radial filtering can be achieved with axial smoothing of transmission data. The axial results suggest that combined radial and axial transmission smoothing could lead to improved noise characteristics with more isotropic resolution degradation
Chiral lattice fermions, minimal doubling, and the axial anomaly
International Nuclear Information System (INIS)
Tiburzi, B. C.
Exact chiral symmetry at finite lattice spacing would preclude the axial anomaly. In order to describe a continuum quantum field theory of Dirac fermions, lattice actions with purported exact chiral symmetry must break the flavor-singlet axial symmetry. We demonstrate that this is indeed the case by using a minimally doubled fermion action. For simplicity, we consider the Abelian axial anomaly in two dimensions. At finite lattice spacing and with gauge interactions, the axial anomaly arises from nonconservation of the flavor-singlet current. Similar nonconservation also leads to the axial anomaly in the case of the naieve lattice action. For minimally doubled actions, however, fine-tuning of the action and axial current is necessary to arrive at the anomaly. Conservation of the flavor nonsinglet vector current additionally requires the current to be fine-tuned. Finally, we determine that the chiral projection of a minimally doubled fermion action can be used to arrive at a lattice theory with an undoubled Dirac fermion possessing the correct anomaly in the continuum limit.
Axial Myopia and its Influence on Diabetic Retinopathy
International Nuclear Information System (INIS)
Tayyab, H.; Haider, M. A.; Bukhari, S. A. H.
Objective: To evaluate the correlation between axial myopia and diabetic retinopathy. Study Design: Cross-sectional study. Place and Duration of Study: Eye Department of Postgraduate Medical Institute, Lahore General Hospital, from August 2012 to February 2013. Methodology: A total of 258 participants suffering from type-2 diabetic retinopathy were included. Axial length was measured by two optometrists using contact type ultrasound biometer. Colored retinal photographs, red free retinal photographs and Fundus Fluorescein Angiography (FFA) were performed on all patients using standard fundus camera. All fundus photographs and angiograms were independently reviewed and graded by two qualified vitreoretinal fellows. Results: Out of 258 patients, 163 were males (63.2%) and 95 (36.8%) were females. Average age of patients was 56.30 +- 7.57 years. Average axial length of right and left eyes were 23.16 mm and 23.15 mm respectively. There was statistically significant negative correlation between axial length and severity of diabetic retinopathy in the right eye, (Spearman correlation = -0.511, p = 0.0001) as well as the left eye (Spearman correlation = -0.522, p = 0.0001). Conclusion: There is a protective influence of longer axial length of globe on the stage and severity of diabetic retinopathy. This study may help in modifying the screening protocol for diabetic retinopathy amongst patients of differing axial lengths. (author)
High Precision Axial Coordinate Readout for an Axial 3-D PET Detector Module using a Wave Length Shifter Strip Matrix
Braem, André; Joram, C; Séguinot, Jacques; Weilhammer, P; De Leo, R; Nappi, E; Lustermann, W; Schinzel, D; Johnson, I; Renker, D; Albrecht, S
We describe a novel method to extract the axial coordinate from a matrix of long axially oriented crystals, which is based on wavelength shifting plastic strips. The method allows building compact 3-D axial gamma detector modules for PET scanners with excellent 3-dimensional spatial, timing and energy resolution while keeping the number of readout channels reasonably low. A voxel resolution of about 10 mm3 is expected. We assess the performance of the method in two independent ways, using classical PMTs and G-APDs to read out the LYSO (LSO) scintillation crystals and the wavelength shifting strips. We observe yields in excess of 35 photoelectrons from the strips for a 511 keV gamma and reconstruct the axial coordinate with a precision of about 2.5 mm (FWHM).
International Nuclear Information System (INIS)
Wyman, V.
Contacts between the South Korean nuclear industry and a combined United Kingdom mission representing AEA Technology and British Nuclear Fuels Limited (BNFL) are reported. Prospects for entering the Korean market in two areas are perceived. The first is waste management and the second is the Safe Integral Reactor (SIR), an advanced pressurized water reactor design. AEA Technology and three collaborators have been promoting SIR as an inherently safe reactor design. Korean interest could be expressed in financial backing for the building of SIR stations in Korea and the opportunity could arise for BNFL to win fuel supply contracts. (UK)
Stability management of high speed axial flow compressor stage through axial extensions of bend skewed casing treatment
Directory of Open Access Journals (Sweden)
DilipkumarBhanudasji Alone
Full Text Available This paper presents the experimental results to understand the performance of moderately loaded high speed single stage transonic axial flow compressor subjected to various configurations of axial extensions of bend skewed casing treatment with moderate porosity. The bend skewed casing treatment of 33% porosity was coupled with rectangular plenum chamber of depth equal to the slots depth. The five axial extensions of 20%, 40%, 60%, 80% and 100% were used for the experimental evaluations of compressor performance. The main objective was to identify the optimum extension of the casing treatment with reference to rotor leading edge which results in maximum stall margin improvements with minimum loss in the stage efficiency. At each axial extension the compressor performance is distinctive. The improvement in the stall margin was very significant at some axial extensions with 4%–5% penalty in the stage efficiency. The compressors stage shows recovery in terms of efficiency at lower axial extensions of 20% and 40% with increase in the peak stage efficiency. Measurements of flow parameters showed the typical behaviors at near stall flow conditions. Hot wire sensor was placed at the rotor upstream in the tip region to capture the oscillations in the inlet axial and tangential velocities at stall conditions. In the absence of casing treatment the compressor exhibit abrupt stall with very high oscillations in the inlet axial and tangential velocity of the flow. The extents of oscillations reduce with bend skewed casing treatment. Few measurements were also performed in the plenum chamber and salient results are presented in this paper.
Refraction and the axial length of the eyeball in patients with the optic disc drusen.
Obuchowska, Iwona; Mariak, Zofia
The aim of the study was to demonstrate the relationship between the optic disc drusen (ODD) and the axial length of the eyeball as well as refractive error. We examined prospectively 40 patients with ODD, 18 men and 22 women, age range from 34 to 69 years. All subjects underwent full ophthalmic examination, visual field testing and color-coded duplex sonography of the ocular vessels. Refraction was determined with an autorefractometer (Topcon RM-8000B) and further refined subjectively. Spherical equivalent refraction was calculated as the spherical dioptre plus one half of the cylindrical dioptre. Axial lengths were measured with a Sonomed ultrasound scanner model E-Z Scan AB5500. Clinical signs were observed in 65% of the eyes with drusen, among them, 38% had symptoms of visual acuity loss and all had visual fields defects. There were 21 eyes (18 eyes with and 3 without drusen), with a recorded refractive error. Significant differences in hyperopia were observed between the eyes with and without drusen (p = 0.048). The rate of occurrence of myopia did not differ significantly between affected and unaffected eyes (p = 0.06). The mean spherical equivalent refraction and axial dimensions of the eye differed significantly among the groups of eyes with and without drusen (p < 0.05). Significant differences in mean values of peak-systolic and end-diastolic velocities (p < 0.001) as well as in the resistivity index (p = 0.047) were observed between eyes with and without drusen. The optic disc drusen are often associated with shorter and hyperopic eyes. This anatomical conditions and vascular factors may contribute to pathogenesis of drusen.
Shen, Ling; You, Qi Sheng; Xu, Xiaolin; Gao, Fei; Zhang, Zhibao; Li, Bin; Jonas, Jost B
To assess differences in scleral and choroidal thickness between eyes with secondary high axial myopia caused by congenital glaucoma, eyes with primary high axial myopia, and nonhighly myopic eyes. The study consisted of 301 Chinese individuals with a mean age of 23.9 ± 22.6 years and mean axial length of 24.8 ± 4.2 mm. It included the "secondary highly myopic group" (SHMG) because of congenital glaucoma (n = 20 eyes; axial length >26.0 mm), the "primary highly myopic group" (PHMG) (n = 73; axial length >26.0 mm), and the remaining nonhighly myopic group (NHMG). The secondary highly myopic group versus the primary highly myopic group had significantly thinner sclera in the pars plana region (343 ± 71 μm versus 398 ± 83 μm; P = 0.006), whereas scleral thickness in other regions did not differ significantly between both highly myopic groups and was significantly thinner in both highly myopic groups than in the NHMG. Mean total scleral volume did not differ significantly (P > 0.20) between any group (SHMG: 659 ± 106 μm; PHMG: 667 ± 128 μm; NHMG: 626 ± 135 μm). Choroidal thickness was significantly thinner in both highly myopic groups than in the NHMG, with no significant differences between both highly myopic groups. Choroidal volume did not differ significantly (P > 0.40) between any of the groups (SHMG: 43 ± 12 μm; PHMG: 43 ± 13 μm; NHMG: 46 ± 17 μm). In secondary high axial myopia, the sclera gets thinner anterior and posterior to the equator; whereas in primary high axial myopia, scleral thinning is predominantly found posterior to the equator. Because volume of sclera and choroid did not differ between any group, scleral and choroidal thinning in myopia may be due to a rearrangement of tissue and not due to the new formation of tissue.
Investigation of axial power gradients near a control rod tip
Energy Technology Data Exchange (ETDEWEB)
Loberg, John, E-mail: firstname.lastname@example.com [Uppsala University, Department of Physics and Astronomy, Division of Applied Nuclear Physics, Box 525, SE-75120 Uppsala (Sweden); Osterlund, Michael, E-mail: firstname.lastname@example.com [Uppsala University, Department of Physics and Astronomy, Division of Applied Nuclear Physics, Box 525, SE-75120 Uppsala (Sweden); Bejmer, Klaes-Hakan, E-mail: email@example.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden); Blomgren, Jan, E-mail: firstname.lastname@example.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden); Kierkegaard, Jesper, E-mail: email@example.com [Vattenfall Nuclear Fuel AB, Jaemtlandsgatan 99, 162 60 Vaellingby, Stockholm (Sweden)
Highlights: > Pin power gradients near BWR control rod tips have been investigated. > A control rod tip is modeled in MCNP and compared to simplified 2D/3D geometry. > Small nodes increases pin power gradients; standard nodes underestimates gradients. > The MCNP results are validated against axial gamma scan of a controlled fuel pin. - Abstract: Control rod withdrawal in BWRs induces large power steps in the adjacent fuel assemblies. This paper investigates how well a 2D/3D method, e.g., CASMO5/SIMULATE5 computes axial pin power gradients adjacent to an asymmetrical control-rod tip in a BWR. The ability to predict pin power gradients accurately is important for safety considerations whereas large powers steps induced by control rod withdrawal can cause Pellet Cladding Interaction. The computation of axial pin power gradients axially around a control rod tip is a challenging task for any nodal code. On top of that, asymmetrical control rod handles are present in some BWR designs. The lattice code CASMO requires diagonal symmetry of all control rod parts. This introduces an error in computed pin power gradients that has been evaluated by Monte Carlo calculations. The results show that CASMO5/SIMULATE5, despite the asymmetrical control rod handle, is able to predict the axial pin power gradient within 1%/cm for axial nodal sizes of 15-3.68 cm. However, a nodal size of 3.68 cm still causes underestimations of pin power gradients compared with 1 cm nodes. Furthermore, if conventional node sizes are used, {approx}15 cm, pin power gradients can be underestimated by over 50% compared with 1 cm nodes. The detailed axial pin power profiles from MCNP are corroborated by measured gamma scan data on fuel rods irradiated adjacent to control rods.
Investigation of axial power gradients near a control rod tip
International Nuclear Information System (INIS)
Loberg, John; Osterlund, Michael; Bejmer, Klaes-Hakan; Blomgren, Jan; Kierkegaard, Jesper
Highlights: → Pin power gradients near BWR control rod tips have been investigated. → A control rod tip is modeled in MCNP and compared to simplified 2D/3D geometry. → Small nodes increases pin power gradients; standard nodes underestimates gradients. → The MCNP results are validated against axial gamma scan of a controlled fuel pin. - Abstract: Control rod withdrawal in BWRs induces large power steps in the adjacent fuel assemblies. This paper investigates how well a 2D/3D method, e.g., CASMO5/SIMULATE5 computes axial pin power gradients adjacent to an asymmetrical control-rod tip in a BWR. The ability to predict pin power gradients accurately is important for safety considerations whereas large powers steps induced by control rod withdrawal can cause Pellet Cladding Interaction. The computation of axial pin power gradients axially around a control rod tip is a challenging task for any nodal code. On top of that, asymmetrical control rod handles are present in some BWR designs. The lattice code CASMO requires diagonal symmetry of all control rod parts. This introduces an error in computed pin power gradients that has been evaluated by Monte Carlo calculations. The results show that CASMO5/SIMULATE5, despite the asymmetrical control rod handle, is able to predict the axial pin power gradient within 1%/cm for axial nodal sizes of 15-3.68 cm. However, a nodal size of 3.68 cm still causes underestimations of pin power gradients compared with 1 cm nodes. Furthermore, if conventional node sizes are used, ∼15 cm, pin power gradients can be underestimated by over 50% compared with 1 cm nodes. The detailed axial pin power profiles from MCNP are corroborated by measured gamma scan data on fuel rods irradiated adjacent to control rods.
Prediction of secular acceleration of axial rotation of Mars
Barkin, Yu. V.
Secular motion of the Earth pole and non-tidal acceleration of its diurnal rotation have obtained rather precise explanation with the help of simple one-point model of the directed transport of fluid masses from a southern hemisphere in northern hemisphere with the general direction, given by geocentric axis OP directed to pole P with coordinates 700N, 10403 E[1]. The another generalized model represents a system of two material points with masses m2 and m1, located on surface of the Earth at poles of geocentric axis OP. Masses are linearly changed in the time with velocities [2]: á¹2 = 0.179 × 1015kg/yrand á¹1 = 0.043 × 1015kg/yr. A reduction of fluid masses of the appropriate thin spherical layer of the Earth correspond to secular increasing of masses of model points. The specified model has allowed to explain values of fundamental geodynamic parameters observably and determined during decades: a direction and velocity of drift of a pole of the Earth; value of non-tidal acceleration of axial rotation; to explain a secular variations of coefficients of the second, third, fourth, sixth and eighth zonal harmonics of a geopotential; coefficients of secular changes of a surface of ocean for the last approximately 150 years; a direction of secular drift of a geocenter and other planetary phenomena [3]. The role of the angular momentum of redistributed masses of the Earth in rotation of the Earth appeared not essential at the given stage of researches. On the essence the offered model has semi-empirical character as it bases on values of velocities of change of masses of points and the given position of axis OP. For their determination and estimations the part of the observant data was used, and other parameters were designed under analytical formulas. The obtained results have precisely confirmed competency and affectivity of geodynamic model [4] about existence of secular drift of a liquid core along radial direction OP with velocity about 2.6 cm/yr in the
ECG-triggered {sup 18}F-fluorodeoxyglucose positron emission tomography imaging of the rat heart is dramatically enhanced by acipimox
Energy Technology Data Exchange (ETDEWEB)
Poussier, Sylvain [Experimental Imaging Platform, Nancyclotep, Nancy (France); CHU-Nancy, Department of Nuclear Medicine, Nancy (France); Nancy University, Faculty of Medicine, Nancy (France); Hopital de Brabois, Nancyclotep, Service de Medecine Nucleaire, Vandoeuvre-les-Nancy (France); Maskali, Fatiha [Experimental Imaging Platform, Nancyclotep, Nancy (France); CHU-Nancy, Department of Nuclear Medicine, Nancy (France); Tran, Nguyen [Nancy University, Faculty of Medicine, Nancy (France); Surgery School, Faculty of Medicine, Nancy (France); INSERM U961, Nancy (France); Person, Christophe; Boutley, Henri; Karcher, Gilles [Experimental Imaging Platform, Nancyclotep, Nancy (France); CHU-Nancy, Department of Nuclear Medicine, Nancy (France); Nancy University, Faculty of Medicine, Nancy (France); Maureira, Pablo [Nancy University, Faculty of Medicine, Nancy (France); Surgery School, Faculty of Medicine, Nancy (France); CHU-Nancy, Department of Cardiac Surgery, Nancy (France); Lacolley, Patrick; Regnault, Veronique [Nancy University, Faculty of Medicine, Nancy (France); INSERM U961, Nancy (France); Fay, Renaud [Centre d' Investigation Clinique, INSERM, U9501, Nancy (France); Marie, Pierre Yves [Experimental Imaging Platform, Nancyclotep, Nancy (France); CHU-Nancy, Department of Nuclear Medicine, Nancy (France); Nancy University, Faculty of Medicine, Nancy (France); INSERM U961, Nancy (France)
{sup 18}F-Fluorodeoxyglucose (FDG) imaging, provided by current positron emission tomography (PET) systems dedicated to small animals, might provide a precise functional assessment of the left ventricle (LV) in rats, although conventional metabolic conditioning by hyperinsulinaemic glucose clamping is not well adapted to this setting. This study was aimed at assessing cardiac FDG PET in rats pre-medicated with acipimox, a potent nicotinic acid derivative yielding comparable image quality to clamping in man. Metabolic conditioning was compared in Wistar rats between a conventional oral glucose loading (1.5 mg/kg) and acipimox, which was given at high but well tolerated doses subcutaneously (25 mg/kg) or orally (50 mg/kg). Myocardial to blood (M/B) activity ratio and myocardial signal to noise (S/N) ratio were analysed on gated FDG PET images. The S/N ratio of the gated cardiac images evolved in parallel with the M/B activity ratio and these two ratios were independently enhanced by glucose loading and acipimox. However, these enhancements were: (1) dramatic for acipimox, especially for the high oral dose of 50 mg/kg (from 2.85 {+-} 0.57 to 10.73 {+-} 0.54 for the M/B ratio of rats with or without glucose loading; p < 0.0001) and (2) much more limited for glucose loading (from 6.61 {+-} 0.49 to 7.89 {+-} 0.41 for the M/B ratio of rats with or without acipimox administration; p = 0.049). With the high oral dose of acipimox, the gated cardiac FDG PET images had very high S/N ratios, at least equivalent to those currently documented in man. Metabolic conditioning by oral doses of acipimox is highly efficient for experimental studies planned with cardiac FDG PET in rats. (orig.)
Analysis of axial compressive loaded beam under random support excitations
Xiao, Wensheng; Wang, Fengde; Liu, Jian
An analytical procedure to investigate the response spectrum of a uniform Bernoulli-Euler beam with axial compressive load subjected to random support excitations is implemented based on the Mindlin-Goodman method and the mode superposition method in the frequency domain. The random response spectrum of the simply supported beam subjected to white noise excitation and to Pierson-Moskowitz spectrum excitation is investigated, and the characteristics of the response spectrum are further explored. Moreover, the effect of axial compressive load is studied and a method to determine the axial load is proposed. The research results show that the response spectrum mainly consists of the beam's additional displacement response spectrum when the excitation is white noise; however, the quasi-static displacement response spectrum is the main component when the excitation is the Pierson-Moskowitz spectrum. Under white noise excitation, the amplitude of the power spectral density function decreased as the axial compressive load increased, while the frequency band of the vibration response spectrum increased with the increase of axial compressive load.
Continuous millennial decrease of the Earth's magnetic axial dipole
Poletti, Wilbor; Biggin, Andrew J.; Trindade, Ricardo I. F.; Hartmann, Gelvam A.; Terra-Nova, Filipe
Since the establishment of direct estimations of the Earth's magnetic field intensity in the first half of the nineteenth century, a continuous decay of the axial dipole component has been observed and variously speculated to be linked to an imminent reversal of the geomagnetic field. Furthermore, indirect estimations from anthropologically made materials and volcanic derivatives suggest that this decrease began significantly earlier than direct measurements have been available. Here, we carefully reassess the available archaeointensity dataset for the last two millennia, and show a good correspondence between direct (observatory/satellite) and indirect (archaeomagnetic) estimates of the axial dipole moment creating, in effect, a proxy to expand our analysis back in time. Our results suggest a continuous linear decay as the most parsimonious long-term description of the axial dipole variation for the last millennium. We thus suggest that a break in the symmetry of axial dipole moment advective sources occurred approximately 1100 years earlier than previously described. In addition, based on the observed dipole secular variation timescale, we speculate that the weakening of the axial dipole may end soon.
Axial clamp for nuclear reactor head penetration conoseal joints
International Nuclear Information System (INIS)
Hackley, T.A.
A method is described for forming a sealed coupling between two bodies, each body presenting an annular abutment surface. The respective bodies are arranged so that their respective annular abutment surfaces are axially adjacent one another, defining a space therebetween, wherein a deformable gasket is disposed within the space. The method comprises: providing one of the bodies with an annular projection; providing the other body with threads for receiving an annular locknut which can be tightened to bear against the annular projection of the one body; applying an external axial forced to the bodies for compressing the abutment surfaces together against the gasket to form a seal between the bodies; immobilizing the bodies relative to one another while the external force is being applied to the bodies by hand-tightening an annular locknut via the threads of the other body until the locknut abuts the annular projection of the one body, substantially preventing relative axial movement between the bodies when the external axial force is withdrawn; and withdrawing the external axial force applied to the bodies, leaving the two bodies coupled together via the seal
Method to Measure Tone of Axial and Proximal Muscle
Gurfinkel, Victor S.; Cacciatore, Timothy W.; Cordo, Paul J.; Horak, Fay B.
The control of tonic muscular activity remains poorly understood. While abnormal tone is commonly assessed clinically by measuring the passive resistance of relaxed limbs1, no systems are available to study tonic muscle control in a natural, active state of antigravity support. We have developed a device (Twister) to study tonic regulation of axial and proximal muscles during active postural maintenance (i.e. postural tone). Twister rotates axial body regions relative to each other about the vertical axis during stance, so as to twist the neck, trunk or hip regions. This twisting imposes length changes on axial muscles without changing the body's relationship to gravity. Because Twister does not provide postural support, tone must be regulated to counteract gravitational torques. We quantify this tonic regulation by the restive torque to twisting, which reflects the state of all muscles undergoing length changes, as well as by electromyography of relevant muscles. Because tone is characterized by long-lasting low-level muscle activity, tonic control is studied with slow movements that produce "tonic" changes in muscle length, without evoking fast "phasic" responses. Twister can be reconfigured to study various aspects of muscle tone, such as co-contraction, tonic modulation to postural changes, tonic interactions across body segments, as well as perceptual thresholds to slow axial rotation. Twister can also be used to provide a quantitative measurement of the effects of disease on axial and proximal postural tone and assess the efficacy of intervention. PMID:22214974
Amphiregulin Antibody and Reduction of Axial Elongation in Experimental Myopia
Directory of Open Access Journals (Sweden)
Wen Jun Jiang
Full Text Available To examine the mechanism of ocular axial elongation in myopia, guinea pigs (age: 2–3 weeks which either underwent unilateral or bilateral lens-induced myopization (group 1 or which were primarily myopic at baseline (group 2 received unilateral intraocular injections of amphiregulin antibody (doses: 5, 10, or 15 μg three times in intervals of 9 days. A third group of emmetropic guinea pigs got intraocular unilateral injections of amphiregulin (doses: 0.25, 0.50 or 1.00 ng, respectively. In each group, the contralateral eyes received intraocular injections of Ringer's solution. In intra-animal inter-eye comparison and intra-eye follow-up comparison in groups 1 and 2, the study eyes as compared to the contralateral eyes showed a dose-dependent reduction in axial elongation. In group 3, study eyes and control eyes did not differ significantly in axial elongation. Immunohistochemistry revealed amphiregulin labelling at the retinal pigment epithelium in eyes with lens-induced myopization and Ringer's solution injection, but not in eyes with amphiregulin antibody injection. Intraocular injections of amphiregulin-antibody led to a reduction of lens-induced axial myopic elongation and of the physiological eye enlargement in young guinea pigs. In contrast, intraocularly injected amphiregulin in a dose of ≤1 ng did not show a significant effect. Amphiregulin may be one of several essential molecular factors for axial elongation.
International Nuclear Information System (INIS)
Lyall, K.
The Business Council of Australia's study on Prospects for Improved Energy Efficiency and the Application of Renewable Energy Resources is summarised. The study estimates that replacement of all off-peak electric units in Australia with solar gas boosted systems would reduce electricity consumption for residential water heating by approximately 25% and almost halve carbon dioxide emissions resulting from residential water heating. Furthermore, substitution of all water heating units in Australia with solar gas systems would reduce total emissions by about 80%. The study concludes that while substitution on such a scale could not readily be achieved even within several decades, the estimates do indicate the significant benefits that might be realised by a long term program. 2 refs., 3 tabs
Application of iterative reconstruction in prospective electrocardiography-triggered CT coronary angiography
International Nuclear Information System (INIS)
Hou Yang; Yu Bing; Guo Qiyong; Wang Yuke; Yu Mei
Objective: To assess the image quality (IQ) of an iterative reconstruction (IR) technique (iDose"4) from prospective electrocardiography (ECG)-triggered coronary CTA on a 256 MSCT scanner and determine the optimal dose reduction using IR that can provide IQ comparable to filtered back projection (FBP). Methods: Prospectively ECG gated CCTA were performed on 120 patients [76 men, 44 women; age: (53 ± 10) y] using a 256-slice MSCT (Brilliance iCT, Philips Healthcare). The control group (Group A , n = 30) were scanned using the conventional tube output (120 kVp, 210 mAs) and reconstructed using FBP. The other 3 groups were scanned with the same kVp but successively reduced tube output as follows: B (n = 30) : 105 mAs , C (n = 30) : 84 mAs: D (n = 30) : 65 mAs and reconstructed using IR levels of L4 to L6, respectively. All images were reconstructed using the same kernel (XCB). Two radiologists graded IQ in a blinded fashion on a 4-point scale (4-excellent, 3-good, 2-fair and 1-poor). Quantitative measurements of CT values, image noise, Signal-to-noise ratio (SNR) and contrast-to-noise ratio (CNR) were obtained in each group. Analysis of variance (ANOVA) was used for comparisons of objective evaluation indices (noise, CNR) and radiation dose (CTDIvol, DLP, ED) between the four groups. The Kruskal-Wallis test was used for comparisons of demographic data and for detection of differences in subjective evaluation of IQ among groups. A level of P < 0.05 was considered statistically significant. A ROC analysis was performed to determine a radiation reduction threshold up to which excellent IQ was maintained. Results: There was no significant differences in objective noise among Groups A (37.4 ± 7.9) HU, B (33.2 ± 7.1) HU, C (35.7 ± 9.8) HU, and D (36.0 ± 6.8) HU (F = 1.48, P = 0.22). There was no significant differences in CNR among Groups A (15.0 ± 2.3), B (16.5 ± 3.6), C (16.3 ± 3.5), and D (15.3 ± 2.8) (F = 1.70, P = 0.17). Group B and C had good and excellent
Relationship of lifestyle and body stature growth with the development of myopia and axial length elongation in Taiwanese elementary school children.
Huang, Chung-Ying; Hou, Chiun-Ho; Lin, Ken-Kuo; Lee, Jiahn-Shing; Yang, Meng-Ling
The development of myopia and growth of the eye, occur at a time when body stature is increasing. To investigate the relationship of lifestyle and body growth with axial elongation and myopia development among schoolchildren aged 7 to 9 years. Prospective study. Children in elementary schools without serious eye disorders were invited to participate. We measured cycloplegic refraction, corneal curvature, intraocular pressure, axial length, body height, and weight. Questionnaires about the children's daily lifestyles, family members' myopia and parents' socio-demographic status were completed. The children were followed up every 6 months in a 3-year period. Bivariate correlations, simple and multiple regression. Eighty-eight children participated in this study. Forty-eight were myopic at the beginning of the study, and their myopia correlated with longer axial length and parental myopia (P = 0.015, 0.012). Sixty-five children (74%) completed the study, and the rates of change per year were -0.43 ± 0.58 (mean + standard deviation) diopters in spherical equivalence, 0.32 ± 0.25 mm in axial length (AL), 5.73 ± 2.71 cm in body height, and 3.84 ± 2.23 kg in weight. The axial length change was positively correlated with the height change (P influence on myopia development, and the environment factor as near work intensity was related to myopia progression.
Bifurcation and chaos of an axially accelerating viscoelastic beam
International Nuclear Information System (INIS)
Yang Xiaodong; Chen Liqun
This paper investigates bifurcation and chaos of an axially accelerating viscoelastic beam. The Kelvin-Voigt model is adopted to constitute the material of the beam. Lagrangian strain is used to account for the beam's geometric nonlinearity. The nonlinear partial-differential equation governing transverse motion of the beam is derived from the Newton second law. The Galerkin method is applied to truncate the governing equation into a set of ordinary differential equations. By use of the Poincare map, the dynamical behavior is identified based on the numerical solutions of the ordinary differential equations. The bifurcation diagrams are presented in the case that the mean axial speed, the amplitude of speed fluctuation and the dynamic viscoelasticity is respectively varied while other parameters are fixed. The Lyapunov exponent is calculated to identify chaos. From numerical simulations, it is indicated that the periodic, quasi-periodic and chaotic motions occur in the transverse vibrations of the axially accelerating viscoelastic beam
Plasma sheath axial phase dynamics in coaxial device
Energy Technology Data Exchange (ETDEWEB)
Soliman, H.M. (Plasma Physics Dept., NRC, Atomic Energy Authority, Cairo (Egypt)); Masoud, M.M. (Plasma Physics Dept., NRC, Atomic Energy Authority, Cairo (Egypt))
The study of the plasma sheath dynamics in the axial phase has been carried out in a 3 kJ coaxial system of Mather type for two different inner electrode (IE) lengths, 20 cm and 31.5 cm. For both lengths, measurements showed that the plasma sheath is splitted into two layers at the breech, which is referred to as a shock front and its magnetic piston. It has been found that the two layers of the plasma current sheath rotate around the inner electrode. At the muzzle the back layer reverse its rotation direction due to the magnetic field structure of the system. Results showed that the axial velocity of the first layer is greater than the second one all over the axial phase within the range between 1.4 and 1.7. (orig.).
Plasma sheath axial phase dynamics in coaxial device
International Nuclear Information System (INIS)
Soliman, H.M.; Masoud, M.M.
The study of the plasma sheath dynamics in the axial phase has been carried out in a 3 kJ coaxial system of Mather type for two different inner electrode (IE) lengths, 20 cm and 31.5 cm. For both lengths, measurements showed that the plasma sheath is splitted into two layers at the breech, which is referred to as a shock front and its magnetic piston. It has been found that the two layers of the plasma current sheath rotate around the inner electrode. At the muzzle the back layer reverse its rotation direction due to the magnetic field structure of the system. Results showed that the axial velocity of the first layer is greater than the second one all over the axial phase within the range between 1.4 and 1.7. (orig.)
Thermocapillary Convection in Floating Zone with Axial Magnetic Fields
Liang, Ruquan; Yang, Shuo; Li, Jizhao
Numerical simulations on the effects of axial magnetic fields on the thermocapillary convection in a liquid bridge of silicone-oil-based ferrofluid under zero gravity have been conducted. The Navier-Stokes equations coupled with the energy conservation equation are solved on a staggered grid, and the mass conserving level set approach is used to capture the free surface deformation of the liquid bridge. The obvious effects of the magnetic fields on the flow pattern as well as the velocity and temperature distributions in the liquid bridge can be detected. The axial magnetic fields suppress the thermocapillary convection and a stagnant flow zone is formed between the circulating flow and the symmetric axis as the magnetic fields increase. The axial magnetic fields affect not only the velocity level inside the liquid bridge but also the velocity level on the free surface. The temperature contours near the free surface illustrates conduction-type temperature profiles at moderate strength fields.
Anisotropic yield surfaces in bi-axial cyclic plasticity
International Nuclear Information System (INIS)
Rider, R.J.; Harvey, S.J.; Breckell, T.H.
Some aspects of the behaviour of yield surfaces and work-hardening surfaces occurring in biaxial cyclic plasticity have been studied experimentally and theoretically. The experimental work consisted of subjecting thin-walled tubular steel specimens to cyclic plastic torsion in the presence of sustained axial loads of various magnitudes. The experimental results show that considerable anisotropy is induced when the cyclic shear strains are dominant. Although the true shapes of yield and work-hardening surfaces can be very complex, a mathematical model is presented which includes both anisotropy and Bauschinger effects. The model is able to qualitatively predict the deformation patterns during a cycle of applied plastic shear strain for a range of sustained axial stresses and also indicate the material response to changes in axial stress. (orig.)
Axial blanket enrichment optimization of the NPP Krsko fuel
International Nuclear Information System (INIS)
Kromar, M.; Kurincic, B.
In this paper optimal axial blanket enrichment of the NPP Krsko fuel is investigated. Since the optimization is dictated by economic categories that can significantly vary in time, two step approach is applied. In the first step simple relationship between the equivalent change in enrichment of axial blankets and central fuel region is established. The relationship is afterwards processed with economic criteria and constraints to obtain optimal axial blanket enrichment. In the analysis realistic NPP Krsko conditions are considered. Except for the fuel enrichment all other fuel characteristics are the same as in the fuel used in the few most recent cycles. A typical reload cycle after the plant power uprate is examined. Analysis has shown that the current blanket enrichment is close to the optimal. Blanket enrichment reduction results in an approximately 100 000 US$ savings per fuel cycle.(author)
Improvement of axial power distribution synthesis methodology in CPC
International Nuclear Information System (INIS)
Kim, H. H.; Gee, S. G.;; Kim, Y. B.; In, W. K.
The capability of axial power distribution synthesis in CPC plays an important role in determining the DNBR and LPD trip caused by CPC. The axial power distribution is synthesized using the cubic spline function based on the three excore detector signals. The axial power distributions are categorized into 8 function sets and each sets are stored as pre-calculated values in CPC to save the calculation time. In this study, the additional function sets, the real break-point function sets and the polynomial function are suggested to evaluate the possibility of improving the synthesis capability in CPC. In addition, RMS errors are compared and evaluated for each synthesis method. As a result, it was confirmed that the function sets stored in CPC were not optimal. The analysis result showed that RMS error could be reduced by selecting the proper function sets suggested in this study
Ball Screw Actuator Including an Axial Soft Stop
Wingett, Paul T. (Inventor); Forrest, Steven Talbert (Inventor); Abel, Steve (Inventor); Woessner, George (Inventor); Hanlon, Casey (Inventor)
An actuator includes an actuator housing, a ball screw, and an axial soft stop assembly. The ball screw extends through the actuator housing and has a first end and a second end. The ball screw is coupled to receive a drive force and is configured, upon receipt of the drive force, to selectively move in a retract direction and an extend direction. The axial soft stop assembly is disposed within the actuator housing. The axial soft stop assembly is configured to be selectively engaged by the ball screw and, upon being engaged thereby, to translate, with compliance, a predetermined distance in the extend direction, and to prevent further movement of the ball screw upon translating the predetermined distance.
Axially modulated arch resonator for logic and memory applications
Hafiz, Md Abdullah Al
We demonstrate reconfigurable logic and random access memory devices based on an axially modulated clamped-guided arch resonator. The device is electrostatically actuated and the motional signal is capacitively sensed, while the resonance frequency is modulated through an axial electrostatic force from the guided side of the microbeam. A multi-physics finite element model is used to verify the effectiveness of the axial modulation. We present two case studies: first, a reconfigurable two-input logic gate based on the linear resonance frequency modulation, and second, a memory element based on the hysteretic frequency response of the resonator working in the nonlinear regime. The energy consumptions of the device for both logic and memory operations are in the range of picojoules, promising for energy efficient alternative computing paradigm.
Linear optical response of carbon nanotubes under axial magnetic field
Moradian, Rostam; Chegel, Raad; Behzad, Somayeh
We considered single walled carbon naotubes (SWCNTs) as real three dimensional (3D) systems in a cylindrical coordinate. The optical matrix elements and linear susceptibility, χ(ω), in the tight binding approximation in terms of one-dimensional wave vector, kz and subband index, l are calculated. In an external axial magnetic field optical frequency dependence of linear susceptibility are investigated. We found that axial magnetic field has two effects on the imaginary part of the linear susceptibility spectrum, in agreement with experimental results. The first effect is broadening and the second, splitting. Also we found that for all metallic zigzag and armchair SWCNTs, the axial magnetic field leads to the creation of a peak with energy less than 1.5 eV, contrary to what is observed in the absence of a magnetic field.
Temporal and Spatial Variability in the Geochemistry of Axial and CoAxial Segment Lavas and their Mantle Sources
Smith, M. C.; Perfit, M. R.; Davis, C.; Kamenov, G. D.
Three spatially related volcanic eruptions along the CoAxial Segment of the Juan de Fuca Ridge (JdFR) have documented emplacements between 1981 and 1993. Two of the historic flows outcrop at the "Flow Site" and were emplaced within less than 12 years and 500 m from one another. The third was emplaced at the "Floc Site" to the south in the 1980s. Previous studies have documented that CoAxial lavas are among the most incompatible element and isotopically depleted lavas along the entire JdFR, whereas the Axial Seamount segment immediately south of CoAxial has erupted the most chemically enriched lavas south of the Endeavor Segment. Geochemical studies have shown little temporal change in the chemistry of recent Axial Seamount eruptives, whereas CoAxial lavas exhibit distinct chemical differences over short time periods. Significant chemical differences observed among depleted CoAxial lavas emplaced close to one another in space and time are in marked contrast to the relatively constant chemical characteristics of enriched lavas erupted at the magmatically more robust Axial segment only 10's of kilometers to the south and west. New trace element and isotopic (Sr, Nd, Pb) geochemical analyses of historic and older CoAxial lavas have resulted in better documentation of interflow and intraflow chemical variation providing an improved understanding of spatial/temporal chemical variability in lavas, and further insight into JdFR magmatic processes. Modeling of major and trace element abundances suggest that the observed intraflow chemical variation within CoAxial lavas is largely due to shallow-level fractional crystallization but that a single fractional crystallization model cannot account for all interflow chemical variation. In fact, elemental and isotopic data require different parental magmas for each of the three recent CoAxial Segment lava flows suggesting very short-term differences or changes in the chemical character of the mantle source region. In particular
[Myopia: frequency of lattice degeneration and axial length].
Martín Sánchez, M D; Roldán Pallarés, M
To evaluate the relationship between lattice retinal degeneration and axial length of the eye in different grades of myopia. A sample of 200 eyes from 124 myopic patients was collected by chance. The average age was 34.8 years (20-50 years) and the myopia was between 0.5 and 20 diopters (D). The eyes were grouped according to the degree of refraction defect, the mean axial length of each group (Scan A) and the frequency of lattice retinal degeneration and the relationship between these variables was studied. The possible influence of age on our results was also considered. For the statistical analysis, the SAS 6.07 program with the variance analysis for quantitative variables, and chi(2) test for qualitative variables with a 5% significance were used. A multivariable linear regression model was also adjusted. The highest frequency of lattice retinal degeneration occurred in those myopia patients having more than 15 D, and also in the group of myopia patients between 3 and 6 D, but this did not show statistical significance when compared with the other myopic groups. If the axial length is assessed, a greater frequency of lattice retinal degeneration is also found when the axial length is 25-27 mm and 29-30 mm, which correspond, respectively, to myopias between 3-10 D and more than 15 D. When the multivariable linear regression model was adjusted, the axial length showed the existence of lattice retinal degeneration (beta 0.41 mm; p=0.08) adjusted by the number of diopters (beta 0.38 mm; plattice retinal degeneration was found for myopias with axial eye length between 29-30 mm (more than 15 D), and 25-27 mm (between 3-10 D).
Spectral analysis in thin tubes with axial heterogeneities
Ferreira, Rita; Mascarenhas, M. Luí sa; Piatnitski, Andrey
In this paper, we present the 3D-1D asymptotic analysis of the Dirichlet spectral problem associated with an elliptic operator with axial periodic heterogeneities. We extend to the 3D-1D case previous 3D-2D results (see [10]) and we analyze the special case where the scale of thickness is much smaller than the scale of the heterogeneities and the planar coefficient has a unique global minimum in the periodic cell. These results are of great relevance in the comprehension of the wave propagation in nanowires showing axial heterogeneities (see [17]).
Manufacture of axially insulated large-area diodes
International Nuclear Information System (INIS)
Ma Weiyi; Zhou Kungang; Wang Youtian; Zhang Dong; Shan Yusheng; Wang Naiyan
The author describes the design and construction of the axially insulated large-area diodes used in the 'Heaven-1'. The four axially insulated large-area diodes are connected to the 10 ohm pulse transmission lines via the vacuum feed through tubes. The experimental results with the diodes are given. The diodes can steadily work at the voltage of 650 kV, and the diode current density is about 80 A per cm 2 with a pulse width of 220 ns. The electron beams with a total energy of 25 kJ are obtained
Study on Predicting Axial Load Capacity of CFST Columns
Ravi Kumar, H.; Muthu, K. U.; Kumar, N. S.
This work presents an analytical study and experimental study on the behaviour and ultimate load carrying capacity of axially compressed self-compacting concrete-filled steel tubular columns. Results of tests conducted by various researchers on 213 samples concrete-filled steel tubular columns are reported and present authors experimental data are reported. Two theoretical equations were derived for the prediction of the ultimate axial load strength of concrete-filled steel tubular columns. The results from prediction were compared with the experimental data. Validation to the experimental results was made.
Light-front view of the axial anomaly
International Nuclear Information System (INIS)
Ji, C.; Rey, S.
Motivated by an apparent puzzle of the light-front vacua incompatible with the axial anomaly, we have considered the two-dimensional massless Schwinger model for an arbitrary interpolating angle of Hornbostel close-quote s interpolating quantization surface. By examining spectral deformation of the Dirac sea under an external electric field semiclassically, we have found that the axial anomaly is quantization angle independent. This indicates an intricate nontrivial vacuum structure present even in the light-front limit. copyright 1996 The American Physical Society
Study of different aerodynamics modifications for small axial flow fan
Bin Abdul Jalil, Anas
En este proyecto, se investigaron los efectos de los álabes en el comportamiento aerodinámico de pequeños ventiladores axiales para disminuir la turbulencia del flujo en su superficie y generalmente para mejorar el rendimiento aerodinámico. Se estudiaron mediante simulación dos modificaciones en la superficie de los alabes de un pequeño ventilador axial (modelo 1, prototipo): la situación de un "winglet" en el extremo del álabe (modelo 2) y el diseño denominado de "aleta de tiburón" (modelo 3...
Dispersive approach to the axial anomaly and nonrenormalization theorem
International Nuclear Information System (INIS)
Pasechnik, R.S.; Teryaev, O.V.
Anomalous triangle graphs for the divergence of the axial-vector current are studied using the dispersive approach generalized for the case of higher orders of perturbation theory. The validity of this procedure is proved up to the two-loop level. By direct calculation in the framework of dispersive approach we have obtained that the two-loop axial-vector-vector (AVV) amplitude is equal to zero. According to the Vainshtein's theorem, the transversal part of the anomalous triangle is not renormalized in the chiral limit. We generalize this theorem for the case of finite fermion mass in the triangle loop
Asymptotic freedom in the axial and Coulomb gauges
International Nuclear Information System (INIS)
Frenkel, J.; Taylor, J.C.
The sources of the negative contribution to the charge renormalization factor gsup(B)/g-1 in Yang-Mills theories are investigated in the axial and Coulomb gauges. In the axial gauge, a Kaellen dispersion relation exists but the spectral function is not positive definite because of the prescription that is used to integrate the singular polarization vectors. In the Coulomb gauge, the negative contributions are (to the lowest order) isolated in the Coulomb self-energy corrections to the Coulomb field. (Auth.)
Rotating stall simulation for axial and centrifugal compressors
Halawa, Taher; Gadala, Mohamed S.
This study presents a numerical simulation of the rotating stall phenomenon in axial and centrifugal compressors with detailed descriptions of stall precursors and its development with time. Results showed that the vaneless region of the centrifugal compressor is the most critical location affected by stall. It was found that the tip leakage flow and the back flow impingement are the main cause of the stall development at the impeller exit area for centrifugal compressors. The results of the axial compressor simulations indicated that the early separated flow combined with the tip leakage flow can block the impeller passages during stall.
Redesigning axial-axial (biaxial) cruciform specimens for very high cycle fatigue ultrasonic testing machines.
Montalvão, Diogo; Wren, Andrew
The necessity to increase performances in terms of lifetime and security in mechanical components or structures is the motivation for intense research in fatigue. Applications range from aeronautics to medical devices. With the development of new materials, there is no longer a fatigue limit in the classical sense, where it was accepted that the fatigue limit is the stress level such that there is no fracture up to 1E7 cycles. The recent development of ultrasonic testing machines where frequencies can go as high as 20 kHz or over enabled tests to be extended to ranges larger than 1E9 in just a few days. This area of studies is now known as Very High Cycle Fatigue (VHCF). On the other hand, most of the existing test equipment in the market for both classical and VHCF are uniaxial test machines. However, critical components used in Engineering applications are usually subjected to complex multi-axial loading conditions. In this paper, it is presented the methodology to redesigning existing cruciform test specimens that can be used to create an in-plane biaxial state of stress when used in 'uniaxial' VHCF ultrasonic testing machines (in this case, the term 'uniaxial' is used not because of the state of stress created at the centre of the specimen, but because of the direction at which the load is applied). The methodology is explained in such a way that it can be expanded to other existing designs, namely cruciform designs, that are not yet used in VHCF. Also, although the approach is presented in simple and logical terms, it may not be that obvious for those who have a more focused approach on fatigue rather than on modal analysis. It is expected that by contributing to bridging the gap between the sciences of modal analysis and fatigue, this research will help and encourage others exploiting new capabilities in VHCF.
Osteoesclerosant axial. Proposal for a new diagnostic approach
International Nuclear Information System (INIS)
Toro, Carlos Enrique; Quintana Duque, Mario Andres; Restrepo, Jose Felix; Quintana, Gerardo; Rondon, Federico; Sanchez, Alvaro; Cons Molina, Fidencio; Gamarra, Antonio Iglesias
Osteosclerosant diseases with axial involvement are a rare group of disorders characterized by a high bone mineral density secondary to impairment in the endochondral and membranous bone formation process. In this article we analyzed the current classification of these diseases and propose a new and simple approach. In addition, we describe the main radiologic, laboratory and clinical keys to arrive to the differential diagnosis
On aspects of vibration of axially moving continua
Hageraats-Ponomareva, S.
In axially moving structures like conveyor belt systems, magnetic tapes, and so on, vibrations occur due to the presence of different kinds of imperfections in the systems. For these structures internal resonances can lead to severe vibrations. Resonance free conveyor belt systems can be constructed
Nonsteroidal Antiinflammatory Drugs for Axial Spondyloarthritis: A Cochrane Review
Kroon, Féline P. B.; van der Burg, Lennart R. A.; Ramiro, Sofia; Landewé, Robert B. M.; Buchbinder, Rachelle; Falzon, Louise; van der Heijde, Désirée
To determine the benefits and harms of nonsteroidal antiinflammatory drugs (NSAID) in axial spondyloarthritis (axSpA). Systematic review using Cochrane Collaboration methodology. randomized controlled trials (RCT) and quasi-RCT (to June 2014), investigating NSAID versus any control for axSpA, and
View of the Axial Field Spectrometer (R807)
In this view of the Axial Field Spectrometer at I8, the vertical uranium/scintillator hadron calorimeter (just left of centre) is retracted to give access to the cylindrical central drift chamber. The yellow iron structure served as a filter to identify muons, with MWPCs and the array of Cherenkov counters to the right.
Supersymmetric axial anomalies and the Wess-Zumino action
International Nuclear Information System (INIS)
Harada, K.; Shizuya, K.
We derive, by an algebraic method, a manifestly supersymmetric extension of Bardeen's minimal form of axial anomalies, which obeys the Wess-Zumino consistency condition. The left-right symmetric form of the anomalies is also obtained by a reduction procedure. We construct the supersymmetric Wess-Zumino effective action and study its low-energy features. (orig.)
Whole-body magnetic resonance imaging in axial spondyloarthritis
DEFF Research Database (Denmark)
Krabbe, Simon; Østergaard, Mikkel; Eshed, Iris
Objective. To investigate whether adalimumab (ADA) reduces whole-body (WB-) magnetic resonance imaging (MRI) indices for inflammation in the entheses, peripheral joints, sacroiliac joints, spine, and the entire body in patients with axial spondyloarthritis (axSpA). Methods. An investigator-initia...
Axial tomography in 3D live cell microscopy
Richter, Verena; Bruns, Sarah; Bruns, Thomas; Piper, Mathis; Weber, Petra; Wagner, Michael; Cremer, Christoph; Schneckenburger, Herbert
A miniaturized setup for sample rotation on a microscope stage has been developed, combined with light sheet, confocal or structured illumination microscopy and applied to living cells as well as to small organisms. This setup permits axial tomography with improved visualization of single cells or small cell clusters as well as an enhanced effective 3D resolution upon sample rotation.
Fission gas retention and axial expansion of irradiated metallic fuel
International Nuclear Information System (INIS)
Fenske, G.R.; Emerson, J.E.; Savoie, F.E.; Johanson, E.W.
Out-of-reactor experiments utilizing direct electrical heating and infrared heating techniques were performed on irradiated metallic fuel. The results indicate accelerated expansion can occur during thermal transients and that the accelerated expansion is driven by retained fission gases. The results also demonstrate gas retention and, hence, expansion behavior is a function of axial position within the pin
Elevated temperature axial and torsional fatigue behavior of Haynes 188
Bonacuse, Peter J.; Kalluri, Sreeramesh
The results of high-temperature axial and torsional low-cycle fatigue experiments performed on Haynes 188, a wrought cobalt-base superalloy, are reported. Fatigue tests were performed at 760 C in air on thin-walled tubular specimens at various ranges under strain control. Data are also presented for coefficient of thermal expansion, elastic modulus, and shear modulus at various temperatures from room to 1000 C, and monotonic and cyclic stress-strain curves in tension and in shear at 760 C. The data set is used to evaluate several multiaxial fatigue life models (most were originally developed for room temperature multiaxial life prediction) including von Mises equivalent strain range (ASME boiler and pressure vessel code), Manson-Halford, Modified Multiaxiality Factor (proposed here), Modified Smith-Watson-Topper, and Fatemi-Socie-Kurath. At von Mises equivalent strain ranges (the torsional strain range divided by the square root of 3, taking the Poisson's ratio to be 0.5), torsionally strained specimens lasted, on average, factors of 2 to 3 times longer than axially strained specimens. The Modified Multiaxiality Factor approach shows promise as a useful method of estimating torsional fatigue life from axial fatigue data at high temperatures. Several difficulties arose with the specimen geometry and extensometry used in these experiments. Cracking at extensometer probe indentations was a problem at smaller strain ranges. Also, as the largest axial and torsional strain range fatigue tests neared completion, a small amount of specimen buckling was observed.
Axial and focal-plane diffraction catastrophe integrals
International Nuclear Information System (INIS)
Berry, M V; Howls, C J
Exact expressions in terms of Bessel functions are found for some of the diffraction catastrophe integrals that decorate caustics in optics and mechanics. These are the axial and focal-plane sections of the elliptic and hyperbolic umbilic diffraction catastrophes, and symmetric elliptic and hyperbolic unfoldings of the X 9 diffraction catastrophes. These representations reveal unexpected relations between the integrals.
Evaluation of electromagnetic shielding effectiveness of multi-axial ...
Indian Academy of Sciences (India)
Aug 26, 2016 ... ... Lecture Workshops · Refresher Courses · Symposia. Home; Journals; Bulletin of Materials Science; Volume 39; Issue 4. Evaluation of electromagnetic shielding effectiveness of multi-axial fabrics and their reinforced PES composites. RAMAZAN ERDEM. Volume 39 Issue 4 August 2016 pp 963-970 ...
Employing a tri-axial accelerometer for estimating energy ...
African Journals Online (AJOL)
The Tritrac-R3D, a portable tri-axial accelerometer, was assessed for its ability to estimate energy expenditure during simulated load carrying activities. The Tritrac data were compared to metabolic data collected simultaneously by a MetaMax ergospirometry system while ten, healthy male subjects (aged 20.7 ±1.4 years) ...
On the axially symmetric equilibrium of a magnetically confined plasma
International Nuclear Information System (INIS)
Lehnert, B.
The axially symmetric equilibrium of a magnetically confined plasma is reconsidered, with the special purpose of studying high-beta schemes with a purely poloidal magnetic field. A number of special solutions of the pressure and magnetic flux functions are shown to exist, the obtained results may form starting-points in a further analysis of physically relevant configurations. (Auth.)
Developmental ossification sequences of the appendicular and axial ...
African Journals Online (AJOL)
A pre-hatch developmental study on ossification sequences of axial and appendicular skeletal system in Kuttanad duck embryos was undertaken using 78 viable embryos. From day 3 to day 7 of incubation no ossification densities were seen both by alizarin red staining and computerized radiography. The first indication of ...
Is a charmed axial-vector meson already found
International Nuclear Information System (INIS)
Matsuda, S.
A calculation is presented of the production rate via e + e - annihilation for a charmed p-wave meson of Jsup(P) = 1 + , based on a non-relativistic quark model of charmed hadrons. The results strongly suggest that the charmed axial-vector meson should be found copiously in association with a ground-state charmed meson. (author)
Radiographic analysis of body composition by computerized axial tomography
International Nuclear Information System (INIS)
Heymsfield, S.B.
Radiographic methods of evaluating body composition have been applied for over five decades. A marked improvement in this approach occurred in the mid-nineteen-seventies with the introduction of computerized axial tomography. High image contrast, cross-sectional imaging and rapid computerized data processing make this technique a sophisticated clinically applicable tool. (author)
Solution of the gauge identities in the axial gauge
International Nuclear Information System (INIS)
Delbourgo, R.
Starting from the spectral representation of the two-point functions in the axial gauge, the gauge identities are solved so as to express the higher-point Green functions linearly in terms of the two-point spectral function. The four-point functions are an important input for investigations of scalar electrodynamics and vector chromodynamics based on the gauge technique. (author)
A cylindrical drift chamber with azimuthal and axial position readout
International Nuclear Information System (INIS)
Bar-Yam, Z.; Cummings, J.P.; Dowd, J.P.; Eugenio, P.; Hayek, M.; Kern, W.; King, E.; Shenhav, N.; Chung, S.U.; Hackenburg, R.W.; Olchanski, C.; Weygand, D.P.; Willutzki, H.J.; Brabson, B.B.; Crittenden, R.R.; Dzierba, A.R.; Gunter, J.; Lindenbusch, R.; Rust, D.R.; Scott, E.; Smith, P.T.; Sulanke, T.; Teige, S.; Denisov, S.; Dushkin, A.; Kochetkov, V.; Lipaev, V.; Popov, A.; Shein, I.; Soldatov, A.; Anoshina, E.V.; Bodyagin, V.A.; Demianov, A.I.; Gribushin, A.M.; Kodolova, O.L.; Korotkikh, V.L.; Kostin, M.A.; Ostrovidov, A.I.; Sarycheva, L.I.; Sinev, N.B.; Vardanyan, I.N.; Yershov, A.A.; Adams, T.; Bishop, J.M.; Cason, N.M.; Sanjari, A.H.; LoSecco, J.M.; Manak, J.J.; Shephard, W.D.; Stienike, D.L.; Taegar, S.A.; Thompson, D.R.; Brown, D.S.; Pedlar, T.; Seth, K.K.; Wise, J.; Zhao, D.; Adams, G.S.; Napolitano, J.; Nozar, M.; Smith, J.A.; Witkowski, M.
A cylindrical multiwire drift chamber with axial charge-division has been constructed and used in experiment E852 at Brookhaven National Laboratory. It serves as a trigger element and as a tracking device for recoil protons in π - p interactions. We describe the chamber's design considerations, details of its construction, electronics, and performance characteristics. (orig.)
Axial Length/Corneal Radius of Curvature Ratio and Refractive ...
African Journals Online (AJOL)
Dec 5, 2017 ... variously described as determined by the ocular biometric variables. There have been many studies on the relationship between refractive error and ocular axial length (AL), anterior chamber depth, corneal radius of curvature (CR), keratometric readings as well as other ocular biometric variables such as ...
Effects of axial coordination on immobilized Mn(salen) catalysts.
Teixeira, Filipe; Mosquera, Ricardo A; Melo, André; Freire, Cristina; Cordeiro, M Natália D S
The consequences of anchoring Mn(salen) catalysts onto a supporting material using one of the vacant positions of the metal center are tackled by studying several Mn(salen) complexes with different axial ligands attached. This is accomplished using Density Functional Theory at the X3LYP/Triple-ζ level of theory and the Atom In Molecules formalism. The results suggest that both Mn(salen) complexes and their oxo derivatives should lie in a triplet ground state. Also, the choice of the axial ligand bears a moderate effect on the energy involved in the oxidation of the former to oxo-Mn(salen) complexes, as well as in the stability of such complexes toward ligand removal by HCl. AIM analysis further suggests that the salen ligand acts as a "charge reservoir" for the metal center, with strong correlations being obtained between the charge of salen and the electron population donated by the axial ligand to the metal center. Moreover, the results suggest that the Mn atom in Mn(salen) complexes holds different hybridization of its valence orbitals depending on the type of axial ligand present in the system.
Evaluation of electromagnetic shielding effectiveness of multi-axial ...
Indian Academy of Sciences (India)
The usage of electrical and electronic equipments has been increasing in daily life, which has a potential hazardous impact on humans and other living organisms. In this paper, multi-axial fabrics containing steel yarns and carbon filaments, and their polyester (PES) resin-reinforced composites have been prepared for ...
Probability analysis of dynamical effects of axial piston hydraulic motor
Sapietova Alzbeta; Dekys Vladimír; Sapieta Milan; Sulka Peter; Gajdos Lukas; Rojek Izabela
The paper presents an analysis of impact force on stopper screw in axial piston hydraulic motor. The solution contains probabilistic description of input variables. If the output parameters of probabilistic solution are compared with arbitrary values and values acquired by analytical solution, the probability of proper operation of the device can be evaluated.
Characterisation of plasmas produced by the "torche à injection axiale"
Jonkers, J.; Selen, L.J.M.; Mullen, van der J.J.A.M.; Timmermans, E.A.H.; Schram, D.C.; Fauchais, P.
Two different kinds of plasmas created by the microwave driven Torche a' Injection Axiale (TIA) are investigated: one with helium and the other with argon as the main gas. By using abs. line intensity measurements, the densities of the excited states are detd. Applying the ideal gas law gives the
Multi-axial mechanical stimulation of tissue engineered cartilage: Review
Directory of Open Access Journals (Sweden)
S D Waldman
Full Text Available The development of tissue engineered cartilage is a promising new approach for the repair of damaged or diseased tissue. Since it has proven difficult to generate cartilaginous tissue with properties similar to that of native articular cartilage, several studies have used mechanical stimuli as a means to improve the quantity and quality of the developed tissue. In this study, we have investigated the effect of multi-axial loading applied during in vitro tissue formation to better reflect the physiological forces that chondrocytes are subjected to in vivo. Dynamic combined compression-shear stimulation (5% compression and 5% shear strain amplitudes increased both collagen and proteoglycan synthesis (76 ± 8% and 73 ± 5%, respectively over the static (unstimulated controls. When this multi-axial loading condition was applied to the chondrocyte cultures over a four week period, there were significant improvements in both extracellular matrix (ECM accumulation and the mechanical properties of the in vitro-formed tissue (3-fold increase in compressive modulus and 1.75-fold increase in shear modulus. Stimulated tissues were also significantly thinner than the static controls (19% reduction suggesting that there was a degree of ECM consolidation as a result of long-term multi-axial loading. This study demonstrated that stimulation by multi-axial forces can improve the quality of the in vitro-formed tissue, but additional studies are required to further optimize the conditions to favour improved biochemical and mechanical properties of the developed tissue.
Axial Torsion of Gangrenous Meckel's Diverticulum Causing Small ...
African Journals Online (AJOL)
dividing the band. Resection and anastomosis of the small bowel including the MD was performed. We hereby report a rare and unusual complication of a MD. Although treatment outcome is generally good, pre-operative diagnosis is often difficult. Key words: Axial torsion, Meckel's diverticulum, small bowel obstruction.
Axial anomaly and index theorem for Dirac-Kaehler fermions
International Nuclear Information System (INIS)
Linhares, C.A.; Mignaco, J.A.; Monteiro, M.A.R.
We present the calculation of the axial anomaly for Dirac-Kaehler fermions in two and four dimensions applying the procedure developed by Seeley to the signature operator in the twisted complex. The result is equal to the one for the twisted spin complex times 2 n/2 (n:number of dimensions) and agrees with the expressions from the index theorem. (author) [pt
Axial anomaly and index theorem for Dirac-Kaehler fermions
International Nuclear Information System (INIS)
Linhares, C.A.; Mignaco, J.A.; Rego Monteiro, M.A.
We present a calculation of the axial anomaly for Dirac-Kaehler fermions in two and four dimensions applying the procedure developed by Seeley to the signature operator in the twisted complex. The result is equal to the one for the twisted spin complex times 2sup(π/2) (n: number of dimensions) and agrees with the expressions from the index theorem. (orig.)
Spin energy levels in axial symmetry: spin 4
Energy Technology Data Exchange (ETDEWEB)
de Biasi, R S; Portella, P D [Instituto Militar de Engenharia, Rio de Janeiro (Brazil). Secao de Engenharia e Ciencia dos Materiais
The spin energy levels in axial symmetry are presented, in graphical and tabular form, for a spin 4. The levels are calculated for five different angles between the applied field and the symmetry axis 0/sup 0/, 30/sup 0/, 45/sup 0/, 60 and 90/sup 0/.
Spin energy levels in axial symmetry: spin 3/2
Energy Technology Data Exchange (ETDEWEB)
de Biasi, R S; Portella, P D [Instituto Militar de Engenharia, Rio de Janeiro (Brazil). Secao de Engenharia e Ciencia dos Materiais
The spin energy levels in axial symmetry are presented, in graphical and tabular form, for a spin 3/2. The levels are calculated for five different angles between the applied field and the symmetry axis: 0/sup 0/, 30/sup 0/, 45/sup 0/, 60/sup 0/ and 90/sup 0/.
Baryon axial charges from chirally improved fermions - first results
Engel, G.; Gattringer, C.; Glozman, L. Y.; Lang, C. B.; Limmer, M.; Mohler, D.; Schäfer, A.
We present first results from dynamical Chirally Improved (CI) fermion simulations for the axial charge $G_A$ of various hadrons. We work with 16^3x32 lattices of spatial extent 2.4 fm and use the variational method with a suitable basis of Jacobi-smeared interpolators to suppress contaminations from excited states.
Axial heterogeneous core concept applied for super phoenix reactor
International Nuclear Information System (INIS)
Batista, J.L.; Renke, C.A.C.; Waintraub, M.; Santos Bastos, W. dos; Brito Aghina, L.O. de.
Always maintaining the current design rules, this paper presents a parametric study on the type of axial heterogeneous core concept (CHA), utilizing a core of fast reactor Super Phenix type, reaching a maximum thermal burnup rate of 150000 M W d/t and being managed in single batch. (author)
Boundary layer flow past a circular cylinder in axial flow
International Nuclear Information System (INIS)
Sawchuk, S.P.; Zamir, M.; Camiletti, S.E.
This paper discusses a study of the laminar boundary layer on a semi-infinite circular cylinder in axial incompressible flow. Unlike previous studies, the present study investigates a full range of this boundary layer problem to determine skin friction, heat transfer and other integral properties of the boundary layer
Axial SPN and radial MOC coupled whole core transport calculation
International Nuclear Information System (INIS)
Cho, Jin-Young; Kim, Kang-Seog; Lee, Chung-Chan; Zee, Sung-Quun; Joo, Han-Gyu
The Simplified P N (SP N ) method is applied to the axial solution of the two-dimensional (2-D) method of characteristics (MOC) solution based whole core transport calculation. A sub-plane scheme and the nodal expansion method (NEM) are employed for the solution of the one-dimensional (1-D) SP N equations involving a radial transverse leakage. The SP N solver replaces the axial diffusion solver of the DeCART direct whole core transport code to provide more accurate, transport theory based axial solutions. In the sub-plane scheme, the radial equivalent homogenization parameters generated by the local MOC for a thick plane are assigned to the multiple finer planes in the subsequent global three-dimensional (3-D) coarse mesh finite difference (CMFD) calculation in which the NEM is employed for the axial solution. The sub-plane scheme induces a much less nodal error while having little impact on the axial leakage representation of the radial MOC calculation. The performance of the sub-plane scheme and SP N nodal transport solver is examined by solving a set of demonstrative problems and the C5G7MOX 3-D extension benchmark problems. It is shown in the demonstrative problems that the nodal error reaching upto 1,400 pcm in a rodded case is reduced to 10 pcm by introducing 10 sub-planes per MOC plane and the transport error is reduced from about 150 pcm to 10 pcm by using SP 3 . Also it is observed, in the C5G7MOX rodded configuration B problem, that the eigenvalues and pin power errors of 180 pcm and 2.2% of the 10 sub-planes diffusion case are reduced to 40 pcm and 1.4%, respectively, for SP 3 with only about a 15% increase in the computing time. It is shown that the SP 5 case gives very similar results to the SP 3 case. (author)
High-resolution axial MR imaging of tibial stress injuries
Directory of Open Access Journals (Sweden)
Mammoto Takeo
Full Text Available Abstract Purpose To evaluate the relative involvement of tibial stress injuries using high-resolution axial MR imaging and the correlation with MR and radiographic images. Methods A total of 33 patients with exercise-induced tibial pain were evaluated. All patients underwent radiograph and high-resolution axial MR imaging. Radiographs were taken at initial presentation and 4 weeks later. High-resolution MR axial images were obtained using a microscopy surface coil with 60 × 60 mm field of view on a 1.5T MR unit. All images were evaluated for abnormal signals of the periosteum, cortex and bone marrow. Results Nineteen patients showed no periosteal reaction at initial and follow-up radiographs. MR imaging showed abnormal signals in the periosteal tissue and partially abnormal signals in the bone marrow. In 7 patients, periosteal reaction was not seen at initial radiograph, but was detected at follow-up radiograph. MR imaging showed abnormal signals in the periosteal tissue and entire bone marrow. Abnormal signals in the cortex were found in 6 patients. The remaining 7 showed periosteal reactions at initial radiograph. MR imaging showed abnormal signals in the periosteal tissue in 6 patients. Abnormal signals were seen in the partial and entire bone marrow in 4 and 3 patients, respectively. Conclusions Bone marrow abnormalities in high-resolution axial MR imaging were related to periosteal reactions at follow-up radiograph. Bone marrow abnormalities might predict later periosteal reactions, suggesting shin splints or stress fractures. High-resolution axial MR imaging is useful in early discrimination of tibial stress injuries.
The Nucleon Axial Form Factor and Staggered Lattice QCD
Energy Technology Data Exchange (ETDEWEB)
Meyer, Aaron Scott [Chicago U.
The study of neutrino oscillation physics is a major research goal of the worldwide particle physics program over the upcoming decade. Many new experiments are being built to study the properties of neutrinos and to answer questions about the phenomenon of neutrino oscillation. These experiments need precise theoretical cross sections in order to access fundamental neutrino properties. Neutrino oscillation experiments often use large atomic nuclei as scattering targets, which are challenging for theorists to model. Nuclear models rely on free-nucleon amplitudes as inputs. These amplitudes are constrained by scattering experiments with large nuclear targets that rely on the very same nuclear models. The work in this dissertation is the rst step of a new initiative to isolate and compute elementary amplitudes with theoretical calculations to support the neutrino oscillation experimental program. Here, the eort focuses on computing the axial form factor, which is the largest contributor of systematic error in the primary signal measurement process for neutrino oscillation studies, quasielastic scattering. Two approaches are taken. First, neutrino scattering data on a deuterium target are reanalyzed with a model-independent parametrization of the axial form factor to quantify the present uncertainty in the free-nucleon amplitudes. The uncertainties on the free-nucleon cross section are found to be underestimated by about an order of magnitude compared to the ubiquitous dipole model parametrization. The second approach uses lattice QCD to perform a rst-principles computation of the nucleon axial form factor. The Highly Improved Staggered Quark (HISQ) action is employed for both valence and sea quarks. The results presented in this dissertation are computed at physical pion mass for one lattice spacing. This work presents a computation of the axial form factor at zero momentum transfer, and forms the basis for a computation of the axial form factor momentum dependence
High-resolution axial MR imaging of tibial stress injuries
Purpose To evaluate the relative involvement of tibial stress injuries using high-resolution axial MR imaging and the correlation with MR and radiographic images. Methods A total of 33 patients with exercise-induced tibial pain were evaluated. All patients underwent radiograph and high-resolution axial MR imaging. Radiographs were taken at initial presentation and 4 weeks later. High-resolution MR axial images were obtained using a microscopy surface coil with 60 × 60 mm field of view on a 1.5T MR unit. All images were evaluated for abnormal signals of the periosteum, cortex and bone marrow. Results Nineteen patients showed no periosteal reaction at initial and follow-up radiographs. MR imaging showed abnormal signals in the periosteal tissue and partially abnormal signals in the bone marrow. In 7 patients, periosteal reaction was not seen at initial radiograph, but was detected at follow-up radiograph. MR imaging showed abnormal signals in the periosteal tissue and entire bone marrow. Abnormal signals in the cortex were found in 6 patients. The remaining 7 showed periosteal reactions at initial radiograph. MR imaging showed abnormal signals in the periosteal tissue in 6 patients. Abnormal signals were seen in the partial and entire bone marrow in 4 and 3 patients, respectively. Conclusions Bone marrow abnormalities in high-resolution axial MR imaging were related to periosteal reactions at follow-up radiograph. Bone marrow abnormalities might predict later periosteal reactions, suggesting shin splints or stress fractures. High-resolution axial MR imaging is useful in early discrimination of tibial stress injuries. PMID:22574840
Two-dimensional nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed
International Nuclear Information System (INIS)
Ghayesh, Mergen H.; Amabili, Marco; Farokhi, Hamed
In the present study, the coupled nonlinear dynamics of an axially moving viscoelastic beam with time-dependent axial speed is investigated employing a numerical technique. The equations of motion for both the transverse and longitudinal motions are obtained using Newton's second law of motion and the constitutive relations. A two-parameter rheological model of the Kelvin–Voigt energy dissipation mechanism is employed in the modelling of the viscoelastic beam material, in which the material time derivative is used in the viscoelastic constitutive relation. The Galerkin method is then applied to the coupled nonlinear equations, which are in the form of partial differential equations, resulting in a set of nonlinear ordinary differential equations (ODEs) with time-dependent coefficients due to the axial acceleration. A change of variables is then introduced to this set of ODEs to transform them into a set of first-order ordinary differential equations. A variable step-size modified Rosenbrock method is used to conduct direct time integration upon this new set of first-order nonlinear ODEs. The mean axial speed and the amplitude of the speed variations, which are taken as bifurcation parameters, are varied, resulting in the bifurcation diagrams of Poincaré maps of the system. The dynamical characteristics of the system are examined more precisely via plotting time histories, phase-plane portraits, Poincaré sections, and fast Fourier transforms (FFTs)
Non-steroidal anti-inflammatory drugs (NSAIDs) for axial spondyloarthritis (ankylosing spondylitis and non-radiographic axial spondyloarthritis)
Kroon, Feline P. B.; van der Burg, Lennart R. A.; Ramiro, Sofia; Landewé, Robert B. M.; Buchbinder, Rachelle; Falzon, Louise; van der Heijde, Désirée
Axial spondyloarthritis (axSpA) comprises ankylosing spondylitis (radiographic axSpA) and non-radiographic (nr-)axSpA and is associated with psoriasis, uveitis and inflammatory bowel disease. Non-steroidal anti-inflammatory drugs (NSAIDs) are recommended as first-line drug treatment. To determine
The characteristics of original geochemical halo in fault zone and its prospecting significance in Xiangyangping uranium deposit
International Nuclear Information System (INIS)
Ouyang Pingning; Huang Manxiang; Liu Xinyang; Chen Yue; Xiao Jianjun
Xiangyangping uranium deposit is a hydrothermal filling deposit controlled by faults. The axial zonation of original element along the fault is sequence of Ni-Rb-Bi-Sn-Cu-W-Hg→As-U-Sb-Mo→Sr-Zn which shows the characteristics of superimposed halos and multiphase mineralization. The distribution characteristics of original halos along structure suggests that uranium mineralization may possess multi-enrichment zones along axial and strata tend. These characteristics are of prospecting significance. (authors)
Generation of parasitic axial flow by drift wave turbulence with broken symmetry: Theory and experiment
Hong, R.; Li, J. C.; Hajjar, R.; Chakraborty Thakur, S.; Diamond, P. H.; Tynan, G. R.
Detailed measurements of intrinsic axial flow generation parallel to the magnetic field in the controlled shear decorrelation experiment linear plasma device with no axial momentum input are presented and compared to theory. The results show a causal link from the density gradient to drift-wave turbulence with broken spectral symmetry and development of the axial mean parallel flow. As the density gradient steepens, the axial and azimuthal Reynolds stresses increase and radially sheared azimuthal and axial mean flows develop. A turbulent axial momentum balance analysis shows that the axial Reynolds stress drives the radially sheared axial mean flow. The turbulent drive (Reynolds power) for the azimuthal flow is an order of magnitude greater than that for axial flow, suggesting that the turbulence fluctuation levels are set by azimuthal flow shear regulation. The direct energy exchange between axial and azimuthal mean flows is shown to be insignificant. Therefore, the axial flow is parasitic to the turbulence-zonal flow system and is driven primarily by the axial turbulent stress generated by that system. The non-diffusive, residual part of the axial Reynolds stress is found to be proportional to the density gradient and is formed due to dynamical asymmetry in the drift-wave turbulence.
Uranium project. Geochemistry prospection
International Nuclear Information System (INIS)
Lambert, J.
Geochemistry studies the distribution of the chemicals elements in the terrestrial crust and its ways to migrate. The terminology used in this report is the following one: 1) Principles of the prospection geochemistry 2) Stages of the prospection geochemistry 3)utility of the prospection geochemistry 4) geochemistry of uranium 5) procedures used within the framework of uranium project 6) Average available 7) Selection of the zones of prospection geochemistry 8) Stages of the prospection, Sample preparation and analisis 9) Presentation of the results
Modelling larval transport in a axial convergence front
Robins, P.
Marine larvae exhibit different vertical swimming behaviours, synchronised by factors such as tidal currents and daylight, in order to aid retention near the parent populations and hence promote production, avoid predation, or to stimulate digestion. This paper explores two types of larval migration in an estuarine axial convergent front which is an important circulatory mechanism in many coastal regions where larvae are concentrated. A parallelised, three-dimensional, ocean model was applied to an idealised estuarine channel which was parameterised from observations of an axial convergent front which occurs in the Conwy Estuary, U.K. (Nunes and Simpson, 1985). The model successfully simulates the bilateral cross-sectional recirculation of an axial convergent front, which has been attributed to lateral density gradients established by the interaction of the lateral shear of the longitudinal currents with the axial salinity gradients. On the flood tide, there is surface axial convergence whereas on the ebb tide, there is (weaker) surface divergence. Further simulations with increased/decreased tidal velocities and with stronger/weaker axial salinity gradients are planned so that the effects of a changing climate on the secondary flow can be understood. Three-dimensional Lagrangian Particle Tracking Models (PTMs) have been developed which use the simulated velocity fields to track larvae in the estuarine channel. The PTMs take into account the vertical migrations of two shellfish species that are commonly found in the Conwy Estuary: (i) tidal migration of the common shore crab (Carcinus maenas) and (ii), diel (daily) migration of the Great scallop (Pecten maximus). These migration behaviours are perhaps the most widespread amongst shellfish larvae and have been compared with passive (drifting) particles in order to assess their relative importance in terms of larval transport. Preliminary results suggest that the net along-estuary dispersal over a typical larval
Segmental and global lordosis changes with two-level axial lumbar interbody fusion and posterior instrumentation
Melgar, Miguel A; Tobler, William D; Ernst, Robert J; Raley, Thomas J; Anand, Neel; Miller, Larry E; Nasca, Richard J
Background Loss of lumbar lordosis has been reported after lumbar interbody fusion surgery and may portend poor clinical and radiographic outcome. The objective of this research was to measure changes in segmental and global lumbar lordosis in patients treated with presacral axial L4-S1 interbody fusion and posterior instrumentation and to determine if these changes influenced patient outcomes. Methods We performed a retrospective, multi-center review of prospectively collected data in 58 consecutive patients with disabling lumbar pain and radiculopathy unresponsive to nonsurgical treatment who underwent L4-S1 interbody fusion with the AxiaLIF two-level system (Baxano Surgical, Raleigh NC). Main outcomes included back pain severity, Oswestry Disability Index (ODI), Odom's outcome criteria, and fusion status using flexion and extension radiographs and computed tomography scans. Segmental (L4-S1) and global (L1-S1) lumbar lordosis measurements were made using standing lateral radiographs. All patients were followed for at least 24 months (mean: 29 months, range 24-56 months). Results There was no bowel injury, vascular injury, deep infection, neurologic complication or implant failure. Mean back pain severity improved from 7.8±1.7 at baseline to 3.3±2.6 at 2 years (p lordosis, defined as a change in Cobb angle ≤ 5°, was identified in 84% of patients at L4-S1 and 81% of patients at L1-S1. Patients with loss or gain in segmental or global lordosis experienced similar 2-year outcomes versus those with less than a 5° change. Conclusions/Clinical Relevance Two-level axial interbody fusion supplemented with posterior fixation does not alter segmental or global lordosis in most patients. Patients with postoperative change in lordosis greater than 5° have similarly favorable long-term clinical outcomes and fusion rates compared to patients with less than 5° lordosis change. PMID:25694920
Plasticity around an Axial Surface Crack in a Cylindrical Shell
DEFF Research Database (Denmark)
Krenk, Steen
of the yield zone. The model is used to analyse published test data on surface cracked pressurised pipes. The analysis consists in COD evaluation and estimate of failure as a consequence of plastic instability. A method is proposed which deals with the problem by simultaneous analysis of a number of cracks......This paper presents a plasticity model for deep axial surface cracks in pressurised pipes. The model is used in an investigation of the relative merits of fracture criteria based on COD and plastic instability. Recent investigations have shown that the inconsistency of the singular bending stress...... on the bending stresses is considerable. In the case of surface cracks moments are induced due to the eccentricity of the crack and transverse shear effects should therefore be included. A plasticity model for a rectangular axial surface crack is developed. Like a previous surface crack model by Erdogen...
Axial offset anomalies and local pH
International Nuclear Information System (INIS)
Tarin, F.; Montes, M.; Izquierdo, J.; Garcia-Sanchez, J.
Small radial and axial offset anomalies (AOA) in some Spanish PWR-type NPP's, in addition to the knowledge of the existence of similar anomalies in U.S. PWR's, led us in 1993 to study this problem. Important parameters were correlated for a database of plant operating data consisting of six cycles of five different PWR plants (all of them of the Westinghouse 3-loop, 12 ft., 17 x 17 fuel design). One of these cycles (the oldest one) followed the standard constant pH 308 = 7.0, and the remaining ones followed a modified elevated pH control strategy (the pH at EOC is typically 7.4). Only for the oldest cycle that used the standard pH control was the in-core and ex-core axial offset values found to be in good agreement with the predictions, and an anomalous soluble boron curve behavior not observed. (author)
Axial Ge/Si nanowire heterostructure tunnel FETs
Energy Technology Data Exchange (ETDEWEB)
Picraux, Sanuel T [Los Alamos National Laboratory; Daych, Shadi A [Los Alamos National Laboratory
The vapor-liquid-solid (VLS) growth of semiconductor nanowires allows doping and composition modulation along their axis and the realization of axial 1 D heterostructures. This provides additional flexibility in energy band-edge engineering along the transport direction which is difficult to attain by planar materials growth and processing techniques. We report here on the design, growth, fabrication, and characterization of asymmetric heterostructure tunnel field-effect transistors (HTFETs) based on 100% compositionally modulated Si/Ge axial NWs for high on-current operation and low ambipolar transport behavior. We discuss the optimization of band-offsets and Schottky barrier heights for high performance HTFETs and issues surrounding their experimental realization. Our HTFET devices with 10 nm PECVD SiN{sub x} gate dielectric resulted in a measured current drive exceeding 100 {mu}A/{mu}m (I/{pi}D) and 10{sup 5} I{sub on}/I{sub off} ratios.
Tests of a new axial sputtering technique in an ECRIS
International Nuclear Information System (INIS)
Scott, R.; Pardo, R.; Vondrasek, R.
Axial and radial sputtering techniques have been used over the years to create beams from an ECRIS at multiple accelerator facilities. Operational experience has shown greater beam production when using the radial sputtering method versus axial sputtering. At Argonne National Laboratory, previous work with radial sputtering has demonstrated that the position of the sputter sample relative to the plasma chamber wall influences sample drain current, beam production and charge state distribution. The possibility of the chamber wall acting as a ground plane which influences the sputtering of material has been considered, and an attempt has been made to mimic this possible ground plane effect with a coaxial sample introduced from the injection end. Results of these tests will be shown as well as comparisons of outputs using the two methods. The paper is followed by the associated poster. (authors)
Axial force in a superconductor magnet journal bearing
Postrekhin, E.; Chong, Wang; Ki Bui, Ma; Chen, Quark; Chu, Wei-Kan
Using superconductors and magnets, a journal bearing could be made from a permanent magnet cylinder in a superconductor ring. We have assembled a prototype superconductor magnet journal bearing of this configuration, and investigated the behavior of the axial force that it can provide. We have put together a numerical model of the interaction between the permanent magnet and the superconductor that is capable of describing these experimental results semi-quantitatively. Combining direct experimental measurements and using the numerical models proposed, we have achieved a qualitative understanding of the behavior of the axial force and its relationship of to the dimensions of the magnet and material quality such as the homogeneity of the superconductor that constitute the bearing.
An Axial Sliding Test for machine elements surfaces
DEFF Research Database (Denmark)
Godi, Alessandro; Grønbæk, J.; Mohaghegh, Kamran
are necessary: a press to provide the normal pressure and a tensile machine to perform the axial movements. The test is calibrated so that the correspondence between the normal pressure and the container advancement is found. Finally, preliminary tests are carried out involving a multifunctional and a fine......Throughout the years, it has become more and more important to find new methods for reducing friction and wear occurrence in machine elements. A possible solution is found in texturing the surfaces under tribological contact, hence the development and spread of plateau-honed surface for cylinder...... liners. To prove the efficacy of a particular textured surface, it is paramount to perform experimental tests under controlled laboratory conditions. In this paper a new test rig simulating pure sliding conditions is presented, dubbed Axial Sliding Test. It presents four major components: a rod, a sleeve...
Computerized axial tomography : the tool in osseointegrated dental implants
International Nuclear Information System (INIS)
Fernandez-Lopez, Otton
Failure rates in rehabilitations with osseointegrated implants are handled through appropriate radiographic preoperative planning. The appropriate length of the implant without running the risk of a perforation of vital structures, has been determined by a radiographic diagnosis. Computerized and conventional axial tomography have proved to be invaluable elements for pre-surgical evaluation. A radiologic guidance is elaborated to perform a computerized axial tomography (CT) of maxillary bones in totally edentulous patients. Surgical guides are constructed from a wax-up emanated from the information of the CT. The CT has proven to be an radiographic indispensable element to achieve the surgical-prosthetic success in osseointegrated dental implants. The CT has allowed the realization of a precise wax-up for making of surgical guide and a precise temporary prostheses in positioning of osseointegrated implants, with the consequent saving time and money for the rehabilitator and patient [es
Laboratory Test Setup for Cyclic Axially Loaded Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina; Ibsen, Lars Bo; Andersen, Lars Vabbersgaard
This paper presents a comprehensive description and the considerations regarding the design of a new laboratory test setup for testing cyclic axially loaded piles in sand. The test setup aims at analysing the effect of axial one-way cyclic loading on pile capacity and accumulated displacements....... Another aim was to test a large diameter pile segment with dimensions resembling full-scale piles to model the interface properties between pile and sand correctly. The pile segment was an open-ended steel pipe pile with a diameter of 0.5 m and a length of 1 m. The sand conditions resembled the dense sand...... determined from the API RP 2GEO standard and from the test results indicated over consolidation of the sand. Two initial one-way cyclic loading tests provided results of effects on pile capacity and accumulated displacements in agreement with other researchers' test results....
Impaired bed mobility: quantitative torque analysis with axial inertial sensors.
Bhidayasiri, Roongroj; Sringean, Jirada; Thanawattano, Chusak
Difficulty in turning in bed is rated as the most troublesome night-time symptom among Parkinson's disease (PD) patients. To develop a practical objective method for home assessment of a patient's ability to turn in bed. Nocturnal parameters and torque of self-turning in bed from 17 PD couples were assessed and compared using a wearable axial sensor for two nights in their homes. The torque of axial rotation which indicates the ability of PD patients to turn in bed was significantly less than their spouses (p turning in bed and total unified Parkinson's Disease Rating Scale score (r = 0.71; p = 0.001), and total Nocturnal Akinesia Dystonia and Cramp score (r = 0.634; p = 0.006). Our study confirms a decreased ability in turning in PD.
Periodicity effects of axial waves in elastic compound rods
DEFF Research Database (Denmark)
Nielsen, R. B.; Sorokin, S. V.
Floquet analysis is applied to the Bernoulli-Euler model for axial waves in a periodic rod. Explicit asymptotic formulae for the stop band borders are given and the topology of the stop band pattern is explained. Eigenfrequencies of the symmetric unit cell are determined by the Phase-closure Prin......Floquet analysis is applied to the Bernoulli-Euler model for axial waves in a periodic rod. Explicit asymptotic formulae for the stop band borders are given and the topology of the stop band pattern is explained. Eigenfrequencies of the symmetric unit cell are determined by the Phase......-closure Principle, and their correspondence with stop band formation is shown. Steady-state and transient dynamics of a periodic rod of finite length are analysed numerically and the difference in structural response when excitation is done in either stop- or pass bands is demonstrated. A physical interpretation...
One-loop calculations in QED in axial gauge
International Nuclear Information System (INIS)
Boos, E.E.; Kurannoy, S.S.
The present paper pursued the aim to test at the simple example of the calculation of the anomalous magnetic moment in quantum electrodynamics the methods of calculating one-loop integrals in the axial gauge, using the dimensional regularization, and to investigate the independence of the results on the choice of the recipe of how to treat the poles in the denominators (k eta) -1 . It is shown that the techniques developed in another paper, as well as in the present paper, can be successfully applied in such calculations, in spite of the peculiarities of the axial gauge that have been discussed previously. The results of the two different ways of treating singularities (k eta) -1 (the principal value and 't Hooft's prescription) turn out to be equal. At the same time it was verified that the Green functions obtained by these calculations near the mass shell in the one-loop approximation satisfy the ward identity
Multichannel singular spectrum analysis of the axial atmospheric angular momentum
Directory of Open Access Journals (Sweden)
Leonid Zotov
Full Text Available Earth's variable rotation is mainly produced by the variability of the AAM (atmospheric angular momentum. In particular, the axial AAM component χ3, which undergoes especially strong variations, induces changes in the Earth's rotation rate. In this study we analysed maps of regional input into the effective axial AAM from 1948 through 2011 from NCEP/NCAR reanalysis. Global zonal circulation patterns related to the LOD (length of day were described. We applied MSSA (Multichannel Singular Spectrum Analysis jointly to the mass and motion components of AAM, which allowed us to extract annual, semiannual, 4-month, quasi-biennial, 5-year, and low-frequency oscillations. PCs (Principal components strongly related to ENSO (El Nino southern oscillation were released. They can be used to study ENSO-induced changes in pressure and wind fields and their coupling to LOD. The PCs describing the trends have captured slow atmospheric circulation changes possibly related to climate variability.
Ultraviolet and infrared aspects of the axial anomaly. I
International Nuclear Information System (INIS)
Horejsi, J.
The paper is the first part of a brief review of some perturbative aspects of the Adler-Bell-Jackiw axial anomaly, described in terms of ultraviolet and infrared behavior of the famous VVA triangle graph. Apart from a general overview of the diversified role played by the anomaly in quantum field theory and particle physics, an elementary introduction is presented to the subject of the anomaly, comprehensible to an uninitiated reader with only a basic background in quantum field theory. The ultraviolet aspects of the anomaly are stressed and the topics covered are the following: vector and axial-vector Ward identities for the VVA triangle graph; the anomaly and several ways to derive it, namely the symmetric momentum cut-off and shifting the integration variables in linearly divergent integrals; the Adler-Rosenberg argument; the Pauli-Villars method; and dimensional regularization. (author) 2 figs., 34 refs
Axial positrons emission tomography: from mouse to human brain imaging
International Nuclear Information System (INIS)
Brard, Emmanuel
Positrons emission tomography is a nuclear imaging technics using nuclear decays. It is used both in clinical and preclinical studies. The later requires the use of small animals such as the mouse. The objective is to obtain the best signal with the best spatial resolution. Yet, a weight ratio between humans and mice indicates the need of a sub-millimeter resolution. A conventional scanner is based on detection modules surrounding the object to image and arranged perpendicularly. This implies a strong relationship between efficiency and spatial resolution. This work focuses on the axial geometry in which detection modules are arranged parallel to the object. This limits the relationship between the figures of merit, leading to both high spatial resolution and efficiency. The simulations of prototypes showed great perspectives in term of sub-millimeter resolution with efficiencies of 15 or 40% according to the scanner's axial extension. These results indicate great perspectives for both clinical and preclinical imaging. (author)
[Inflammatory spinal diseases: axial spondyloarthritis : Central importance of imaging].
Baraliakos, X; Fruth, M; Kiltz, U; Braun, J
The diagnosis of axial spondyloarthritis (axSpA) includes classical ankylosing spondylitis (AS) as well as earlier stages and abortive courses of the disease, in which structural alterations have not yet occurred. These are classified as non-radiographic axSpA (nr-axSpa). Inflammatory changes in the entire axial skeleton are characteristic for axSpA and can be visualized by magnetic resonance imaging (MRI), while in most patients structural alterations, such as new bone formation with syndesmophytes and ankylosis develop in the later course of the disease. These bony alterations can best be visualized by conventional radiography and by computed tomography. Certain MRI sequences are nowadays considered as the standard method for depiction of inflammatory changes in axSpA. The introduction of MRI has led to a paradigm shift for this disease because the inflammatory lesions characteristic for the disease can be visualized at an early stage using appropriate MRI sequences.
Buckling localization in a cylindrical panel under axial compression
DEFF Research Database (Denmark)
Tvergaard, Viggo; Needleman, A.
Localization of an initially periodic buckling pattern is investigated for an axially compressed elastic-plastic cylindrical panel of the type occurring between axial stiffeners on cylindrical shells. The phenomenon of buckling localization and its analogy with plastic flow localization in tensile...... test specimens is discussed in general. For the cylindrical panel, it is shown that buckling localization develops shortly after a maximum load has been attained, and this occurs for a purely elastic panel as well as for elastic-plastic panels. In a case where localization occurs after a load maximum......, but where subsequently the load starts to increase again, it is found that near the local load minimum, the buckling pattern switches back to a periodic type of pattern. The inelastic material behavior of the panel is described in terms of J(2) corner theory, which avoids the sometimes unrealistically high...
Classical theory of the Kumakhov radiation in axial channeling
International Nuclear Information System (INIS)
Khokonov, M.K.; Komarov, F.F.; Telegin, V.I.
The paper considers radiation of ultrarelativistic electrons in axial channeling initially predicted by Kumakhov. The consideration is based on the results of solution of the Fokker-Planck equation. The spectral-angular characteristics of the Kumakhov radiation in thick single crystals are calculated. It is shown that in heavy single crystals the energy losses on radiation can amount to a considerable portion of the initial beam energy. The possibility of a sharp increase of radiation due to a decrease of crystal temperature is discussed. It is shown that radiation intensity in axial channeling is weakly dependent on the initial angle of the electron entrance into the channel if this angle changes within the limits of a critical one. (author)
High pressure axial flow fans for modern coal power stations
Energy Technology Data Exchange (ETDEWEB)
Cyrus, Vaclav [AHT Energetika s.r.o., Praha (Czech Republic); Koci, Petr [ZVVZ Milevsko a.s. (Czech Republic)
Brown coal fired power stations, located in Northern Bohemia, have mostly older boiler blocks with an output of 110 and 200 MWe. Flue gases are cleaned by the desulphurization plants installed between 1993 and 1997. Usually, each boiler block has two air fans and one to three flue gas fans. Flue gas fans operate in severe conditions; fan blades should be resistant to the flue gases containing sulphur and acid drops with the operating temperature at 170 C to 190 C. Additionally, flue gas also often contains ash particles. Currently, some boiler blocks are gradually being refurbished. New blocks with an electrical power output of 600 to 700 MWe are at the design stage. Submitted paper shows our design study of one stage axial flow fan for the new blocks. Results from the new aerodynamic research of the axial flow stages were used in the fan design. (orig.)
Axial weak currents in the Wess-Zumino term
International Nuclear Information System (INIS)
Fujikawa, Kazuo
In a simplified model lagrangian of 3 quarks with an SU(2)sub(L) gauging of chiral SU(3)sub(L)xSU(3)sub(R) to introduce W-boson, we analyse certain complications associated with the low-energy theorem including axial weak fields. We first show that the low-energy amplitude is independent of the form of the quark-level anomalous identity, whether in the covariant form or the consistent form. However, the interplay of the short-distance dynamics (anomalous identity) and the long-distance dynamics (low-energy theorem) becomes involved in the presence of axial fields. We then discuss what kinds of conditions single out the gauged Wess-Zumino term as a low-energy effective action. The connection of the low-energy theorem with the 't Hooft anomaly matching condition is also discussed. (orig.)
Colonic surveillance by CT colonography using axial images only
International Nuclear Information System (INIS)
Bruzzi, John F.; Brennan, Darren D.; Fenlon, Helen M.; Moss, Alan C.; MacMathuna, Padraic
Patients at increased risk of colon cancer require strict colon surveillance. Our objective was to establish the efficacy of 2D axial CT colonography as a surveillance test when performed in routine clinical practice. Eighty-two patients at increased risk of colon cancer underwent CT colonography followed by conventional colonoscopy on the same morning. CT colonography studies were performed on a four-ring multidetector CT scanner (100 mAs, 120 kVp, 4 x 2.5 collimation) and were interpreted by two radiologists using 2D axial images only. Results were correlated with findings at colonoscopy. Note was made of subsequent histology reports from polypectomy specimens. A total of 52 polyps were detected at colonoscopy. Using 2D axial images alone, with no recourse to 2D multiplanar or 3D views, the sensitivity of CT colonography was 100, 33 and 19% for polyps larger than 9, 6-9 and smaller than 6 mm, respectively. Per-patient specificities were 98.8, 96 and 81.5%, respectively. Twenty-nine percent of polyps smaller than 1 cm were adenomatous and there were no histological features of severe dysplasia. CT colonography is a useful colon surveillance tool for patients at increased risk of colon cancer. It has a high specificity for identifying patients who should proceed to colonoscopy and polypectomy, while allowing further colon examination to be deferred in patients with normal studies. Using 2D axial images only, CT colonography can be performed as part of the daily CT workload, with a very low rate of referral for unnecessary colonoscopy. (orig.)
Overview of the Axial Field Spectrometer in the ISR tunnel
A view of the Axial Field Spectrometer – the last large experiment at the ISR. The horizontal top and vertical outer arrays of the uranium-scintillator hadron calorimeter are clear to be seen, with the blue cylindrical pole piece of the magnet just visible. The pipes that are visible in front of the pole piece are cryogenic feed pipes for the superconducting low-beta quadrupoles.
The nucleon axial charge in full lattice QCD
International Nuclear Information System (INIS)
Edwards, R.G.; Richards, D.G.; Fleming, G.T.; Haegler, P.; Technische Univ. Muenchen, Garching; Negele, J.W.; Pochinsky, A.V.; Orginos, K.; College of William and Mary, Williamsburg, VA; Renner, D.B.; Schroers, W.
The nucleon axial charge is calculated as a function of the pion mass in full QCD. Using domain wall valence quarks and improved staggered sea quarks, we present the first calculation with pion masses as light as 354 MeV and volumes as large as (3.5 fm) 3 . We show that finite volume effects are small for our volumes and that a constrained fit based on finite volume chiral perturbation theory agrees with experiment within 7% statistical errors. (orig.)
Axial anomaly and mixing: From real to highly virtual photons
International Nuclear Information System (INIS)
Klopot, Yaroslav N.; Teryaev, Oleg V.; Oganesian, Armen G.
The relation for transition form factors of η and η ' is obtained by combining the exact nonperturbative QCD sum rule, following from the dispersive representation of axial anomaly, and quark-hadron duality. It is valid at all virtual photon momenta and allows one to express the transition form factors entirely in terms of meson decay constants. This relation is in a good agreement with experimental data.
Channel of Axial Injection of DC-60 Cyclotron
Gikal, B N; Bogomolov, S L; Borisenko, A N; Borisov, O N; Gulbekyan, G G; Ivanenko, I A; Kalagin, I V; Kazacha, V I; Kazarinov, N Yu; Khabarov, M V; Lysukhin, S N; Melnikov, V N; Paschenko, S V; Tikhomirov, A V
The design study and realization of the axial injection beam line of DC-60 cyclotron constructed at the Flerov Laboratory of Nuclear Reactions of the Joint Institute for Nuclear Research are given. The channel allows one to transport and to inject into the cyclotron ions with mass-to-charge ratio $A/Z$ being within interval A/Z=6-12 and kinetic energy up to 17 $Z/A$ keV/m.u.
Moving blade for steam turbines with axial flow
International Nuclear Information System (INIS)
Raschke, K.; Wehle, G.
The invention concerns the improvement of the production of moving blades for steam turbines with axial flow, especially of multi-blades produced by welding of the top plates. It is proposed to weld the top plates before the moving blades are fitted into the rotor. Welding is this made much easier and can be carried out under protective gas and with better results. (UWI) [de
Static axially symmetric gravitational fields with shell sources
International Nuclear Information System (INIS)
McCrea, J.D.
Israel's (Israel, W., 1966, Nuovo Cim., vol.44, 1-14) method for treating surface layers in general relativity is applied to construct shell sources for exterior static axially symmetric gravitational fields. Consideration is restricted to cases in which the 3-cylinder representing the history of the shell is an equipotential surface of the exterior field and consequently the space-time inside this 3-cylinder is flat. (author)
Radiation of electrons in an electromagnetic axial trap
International Nuclear Information System (INIS)
Toropova, A.I.
The version of a trap. wherein particles move in a homogeneous constant magnetic field and electrostatic field, formed by two equipotential planes and rotation axial surface, is proposed. The solution of canonic equations is found. It is shown that interaction of electrons with the radiation field leads to damping parametric resonance. The trap model, accounting for the finite conductivity of the resonator walls and losses by collisions with gas, is studied
Investigation on a procedure for optimal axial depth of cut accuracy in micromilling
DEFF Research Database (Denmark)
Bissacco, Giuliano; Hansen, Hans Nørgaard; De Chiffre, Leonardo
On the basis of a previously developed procedure for control of axial depth of cut in high accuracy micromilling operations, this paper presents an investigation on the estimation of the uncertainty of the set axial depth of cut.......On the basis of a previously developed procedure for control of axial depth of cut in high accuracy micromilling operations, this paper presents an investigation on the estimation of the uncertainty of the set axial depth of cut....
Fundamental metallurgical aspects of axial splitting in zircaloy cladding
International Nuclear Information System (INIS)
Chung, H. M.
Fundamental metallurgical aspects of axial splitting in irradiated Zircaloy cladding have been investigated by microstructural characterization and analytical modeling, with emphasis on application of the results to understand high-burnup fuel failure under RIA situations. Optical microscopy, SEM, and TEM were conducted on BWR and PWR fuel cladding tubes that were irradiated to fluence levels of 3.3 x 10 21 n cm -2 to 5.9 x 10 21 n cm -2 (E > 1 MeV) and tested in hot cell at 292--325 C in Ar. The morphology, distribution, and habit planes of macroscopic and microscopic hydrides in as-irradiated and posttest cladding were determined by stereo-TEM. The type and magnitude of the residual stress produced in association with oxide-layer growth and dense hydride precipitation, and several synergistic factors that strongly influence axial-splitting behavior were analyzed. The results of the microstructural characterization and stress analyses were then correlated with axial-splitting behavior of high-burnup PWR cladding reported for simulated-RIA conditions. The effects of key test procedures and their implications for the interpretation of RIA test results are discussed
Accretion mode of oceanic ridges governed by axial mechanical strength
Sibrant, A. L. R.; Mittelstaedt, E.; Davaille, A.; Pauchard, L.; Aubertin, A.; Auffray, L.; Pidoux, R.
Oceanic spreading ridges exhibit structural changes as a function of spreading rate, mantle temperature and the balance of tectonic and magmatic accretion. The role that these or other processes have in governing the overall shape of oceanic ridges is unclear. Here, we use laboratory experiments to simulate ridge spreading in colloidal aqueous dispersions whose rheology evolves from purely viscous to elastic and brittle when placed in contact with a saline water solution. We find that ridge shape becomes increasingly linear with spreading rate until reaching a minimum tortuosity. This behaviour is predicted by the axial failure parameter ΠF, a dimensionless number describing the balance of brittle and plastic failure of axial lithosphere. Slow-spreading, fault-dominated and fast-spreading, fluid intrusion-dominated ridges on Earth and in the laboratory are separated by the same critical ΠF value, suggesting that the axial failure mode governs ridge geometry. Values of ΠF can also be calculated for different mantle temperatures and applied to other planets or the early Earth. For higher mantle temperatures during the Archaean, our results preclude the predicted formation of large tectonic plates at high spreading velocity.
Taming axial dispersion in hydrodynamic chromatography columns through wall patterning
Adrover, Alessandra; Cerbelli, Stefano; Giona, Massimiliano
A well-known limitation of hydrodynamic chromatography arises from the synergistic interaction between transverse diffusion and streamwise convection, which enhances axial dispersion through the Taylor-Aris mechanism. We show that a periodic sequence of slip/no-slip conditions at the channel walls (e.g., representing wall indentations hosting stable air pockets) can significantly reduce axial dispersion, thus enhancing separation performance. The theoretical/numerical analysis is based on a generalization of Brenner's macrotransport approach to solute transport, here modified to account for the finite-size of the suspended particles. The most effective dispersion-taming outcome is observed when the alternating sequence of slip/no-slip conditions yields non-vanishing cross-sectional flow components. The combination of these components with the hindering interaction between the channel boundaries and the finite-sized particles gives rise to a non-trivial solution of Brenner's problem on the unit periodic cell, where the cross-sectional particle number density departs from the spatially homogeneous condition. In turn, this effect impacts upon the solution of the so-called b-field defining the large-scale dispersion tensor, with an overall decremental effect on the axial dispersion coefficient and on the Height Equivalent of a Theoretical Plate.
Axial power monitoring uncertainty in the Savannah River Reactors
International Nuclear Information System (INIS)
Losey, D.C.; Revolinski, S.M.
The results of this analysis quantified the uncertainty associated with monitoring the Axial Power Shape (APS) in the Savannah River Reactors. Thermocouples at each assembly flow exit map the radial power distribution and are the primary means of monitoring power in these reactors. The remaining uncertainty in power monitoring is associated with the relative axial power distribution. The APS is monitored by seven sensors that respond to power on each of nine vertical Axial Power Monitor (APM) rods. Computation of the APS uncertainty, for the reactor power limits analysis, started with a large database of APM rod measurements spanning several years of reactor operation. A computer algorithm was used to randomly select a sample of APSs which were input to a code. This code modeled the thermal-hydraulic performance of a single fuel assembly during a design basis Loss-of Coolant Accident. The assembly power limit at Onset of Significant Voiding was computed for each APS. The output was a distribution of expected assembly power limits that was adjusted to account for the biases caused by instrumentation error and by measuring 7 points rather than a continuous APS. Statistical analysis of the final assembly power limit distribution showed that reducing reactor power by approximately 3% was sufficient to account for APS variation. This data confirmed expectations that the assembly exit thermocouples provide all information needed for monitoring core power. The computational analysis results also quantified the contribution to power limits of the various uncertainties such as instrumentation error
Imaging results and TOF studies with axial PET detectors
Joram, Christian
We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the held of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The Fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations ( <2 mm FWHM in all three coordinates over the complete held of view) and also demonstrated the ability to include Compton interactions (inter-cr...
Imaging results and TOF studies with axial PET detectors
Joram, Christian
We have developed a fully operational PET demonstrator setup which allows true 3D reconstruction of the 511 keV photons and therefore leads to practically parallax free images. The AX-PET concept is based on thin 100 mm long scintillation crystals (LYSO), axially oriented and arranged in layers around the field of view. Layers of wavelength shifting plastic strips mounted in between the crystal layers give the axial coordinate. Both crystals and WLS strips are individually read out by G-APD (SiPM) photodetectors. The fully scalable concept overcomes the dilemma of sensitivity versus spatial resolution which is inherent to classical PET designs. A demonstrator set-up based on two axial modules was exhaustively characterized using point-like sources, phantoms filled with radiotracer and finally rats and a mouse. The results entirely meet the performance expectations (PET concept making use of the novel digital SiPM detectors by Philips. After reproducing comparable energy and spatial resolution on a small digital AX-PET set-up with 100 mm long crystals, we demonstrated a coincidence resolving time of about 210 ps FWHM.
Multi technical analysis of wear mechanisms in axial piston pumps
Schuhler, G.; Jourani, A.; Bouvier, S.; Perrochat, J.-M.
Axial piston pumps convert a motor rotation motion into hydraulic or pneumatic power. Their compactness and efficiency of approximately 0.9 make them suitable for actuation applications especially in aeronautics. However, they suffer a limited life due to the wear of their components. In the literature, studies of axial piston pumps deal with contact between its different elements under lubrication conditions. Nevertheless, they are more focused on analytic or numerical approaches. This study consists in an experimental analysis of worn pump components to highlight and understand wear mechanisms. Piston shoes are central components in the axial piston pump since they are involved in three tribological contacts. These three contacts are thereby studied: piston shoes/swashplate, piston shoes/pistons and piston shoes/shoes hold down plate (SHDP). To perform this analysis, helicopter hydraulic pumps after different operating times have been studied. The wear damage mechanisms and wear debris are analysed using SEM observations. 3D surface roughness measurements are then used to characterize worn surfaces. The observations reveal that in the contact between shoes and swashplate, the main wear mechanism is three-body abrasive wear due to coarse carbides removal. Between shoes and pistons, wear occurs in a less severe way and is mainly due to the debris generated in the first contact and conveyed by the lubricating fluid. In the third contact, the debris are also the prime cause of the abrasive wear and the generation of deep craters in the piston shoes.
HTS axial flux induction motor with analytic and FEA modeling
Energy Technology Data Exchange (ETDEWEB)
Li, S., E-mail: email@example.com; Fan, Y.; Fang, J.; Qin, W.; Lv, G.; Li, J.H.
Highlights: •A high temperature superconductor axial flux induction motor and a novel maglev scheme are presented. •Analytic method and finite element method have been adopted to model the motor and to calculate the force. •Magnetic field distribution in HTS coil is calculated by analytic method. •An effective method to improve the critical current of HTS coil is presented. •AC losses of HTS coils in the HTS axial flux induction motor are estimated and tested. -- Abstract: This paper presents a high-temperature superconductor (HTS) axial-flux induction motor, which can output levitation force and torque simultaneously. In order to analyze the character of the force, analytic method and finite element method are adopted to model the motor. To make sure the HTS can carry sufficiently large current and work well, the magnetic field distribution in HTS coil is calculated. An effective method to improve the critical current of HTS coil is presented. Then, AC losses in HTS windings in the motor are estimated and tested.
A mini axial and a permanent maglev radial heart pump.
Qian, Kun-Xi; Ru, Wei-Min; Wang, Hao; Jing, Teng
The implantability and durability have been for decades the focus of artificial heart R&D. A mini axial and a maglev radial pump have been developed to meet with such requirements.The mini axial pump weighing 27g (incl.5g rotor) has an outer diameter of 21mm and a length of 10mm in its largest point, but can produce a maximal blood flow of 6l/min with 50mmHg pressure increase. Therefore, it is suitable for the patients of 40-60kg body weight. For other patients of 60-80kg or 80-100kg body weight, the mini axial pumps of 23mm and 25mm outer diameter had been developed before, these devices were acknowledged to be the world smallest LVADs by Guinness World Record Center in 2004.The permanent maglev radial pump weighing 150g is a shaft-less centrifugal pump with permanent magnetic bearings developed by the author. It needs no second coil for suspension of the rotor except the motor coil, different from all other maglev pumps developed in USA, Japan, European, etc. Thus no detecting and controlling systems as well as no additional power supply for maglev are necessary. The pump can produce a blood flow up to as large as 10l/min against 100mmHg pressure.An implantable and durable blood pump will be a viable alternative to natural donor heart for transplantation.
Axial temperatures and fuel management models for a HTR system
Energy Technology Data Exchange (ETDEWEB)
Hansen, U
In the HTR system, there is a large difference in temperature between different parts of the reactor core. The softer neutron spectrum in the upper colder core regions tends to shift the power productions in the fresh fuel upwards. As uranium 235 depletes and plutonium with its higher cross sections in the lower hot regions is built-up, an axial power flattening takes place. These effects have been studied in detail for a single column in an equilibrium environment. The aim of this paper is to relate these findings to a whole reactor core and to investigate the influence of axial temperatures on the overall performance and in particular, the fuel management scheme chosen for the reference design. A further objective has been to calculate the reactivity requirements for different part load conditions and for various daily and weekly load diagrams. As the xenon cross section changes significantly with temperature these investigations are performed for an equilibrium core with due representation of axial temperature zones.
The New Performance Calculation Method of Fouled Axial Flow Compressor
Directory of Open Access Journals (Sweden)
Huadong Yang
Full Text Available Fouling is the most important performance degradation factor, so it is necessary to accurately predict the effect of fouling on engine performance. In the previous research, it is very difficult to accurately model the fouled axial flow compressor. This paper develops a new performance calculation method of fouled multistage axial flow compressor based on experiment result and operating data. For multistage compressor, the whole compressor is decomposed into two sections. The first section includes the first 50% stages which reflect the fouling level, and the second section includes the last 50% stages which are viewed as the clean stage because of less deposits. In this model, the performance of the first section is obtained by combining scaling law method and linear progression model with traditional stage stacking method; simultaneously ambient conditions and engine configurations are considered. On the other hand, the performance of the second section is calculated by averaged infinitesimal stage method which is based on Reynolds' law of similarity. Finally, the model is successfully applied to predict the 8-stage axial flow compressor and 16-stage LM2500-30 compressor. The change of thermodynamic parameters such as pressure ratio, efficiency with the operating time, and stage number is analyzed in detail.
HTS axial flux induction motor with analytic and FEA modeling
International Nuclear Information System (INIS)
Li, S.; Fan, Y.; Fang, J.; Qin, W.; Lv, G.; Li, J.H.
Highlights: •A high temperature superconductor axial flux induction motor and a novel maglev scheme are presented. •Analytic method and finite element method have been adopted to model the motor and to calculate the force. •Magnetic field distribution in HTS coil is calculated by analytic method. •An effective method to improve the critical current of HTS coil is presented. •AC losses of HTS coils in the HTS axial flux induction motor are estimated and tested. -- Abstract: This paper presents a high-temperature superconductor (HTS) axial-flux induction motor, which can output levitation force and torque simultaneously. In order to analyze the character of the force, analytic method and finite element method are adopted to model the motor. To make sure the HTS can carry sufficiently large current and work well, the magnetic field distribution in HTS coil is calculated. An effective method to improve the critical current of HTS coil is presented. Then, AC losses in HTS windings in the motor are estimated and tested
Axial and Centrifugal Compressor Mean Line Flow Analysis Method
Veres, Joseph P.
This paper describes a method to estimate key aerodynamic parameters of single and multistage axial and centrifugal compressors. This mean-line compressor code COMDES provides the capability of sizing single and multistage compressors quickly during the conceptual design process. Based on the compressible fluid flow equations and the Euler equation, the code can estimate rotor inlet and exit blade angles when run in the design mode. The design point rotor efficiency and stator losses are inputs to the code, and are modeled at off design. When run in the off-design analysis mode, it can be used to generate performance maps based on simple models for losses due to rotor incidence and inlet guide vane reset angle. The code can provide an improved understanding of basic aerodynamic parameters such as diffusion factor, loading levels and incidence, when matching multistage compressor blade rows at design and at part-speed operation. Rotor loading levels and relative velocity ratio are correlated to the onset of compressor surge. NASA Stage 37 and the three-stage NASA 74-A axial compressors were analyzed and the results compared to test data. The code has been used to generate the performance map for the NASA 76-B three-stage axial compressor featuring variable geometry. The compressor stages were aerodynamically matched at off-design speeds by adjusting the variable inlet guide vane and variable stator geometry angles to control the rotor diffusion factor and incidence angles.
Notchless is required for axial skeleton formation in mice.
Directory of Open Access Journals (Sweden)
Sarah Beck-Cormier
Full Text Available Maintenance of cell survival is essential for proper embryonic development. In the mouse, Notchless homolog 1 (Drosophila (Nle1 is instrumental for survival of cells of the inner cell mass upon implantation. Here, we analyze the function of Nle1 after implantation using the Meox2(tm1(creSor mouse that expresses the Cre recombinase specifically in the epiblast at E5.5. First, we find that NLE1 function is required in epiblast cells, as Nle1-deficient cells are rapidly eliminated. In this report, we also show that the Meox2(Cre transgene is active in specific tissues during organogenesis. In particular, we detect high Cre expression in the vertebral column, ribs, limbs and tailbud. We took advantage of this dynamic expression profile to analyze the effects of inducing mosaic deletion of Nle1 in the embryo. We show that Nle1 deletion in this context, results in severe developmental anomalies leading to lethality at birth. Mutant embryos display multiple developmental defects in particular during axial skeletal formation. We also provide evidence that axial defects are due to an increase in apoptotic cell death in the somite at E9.5. These data demonstrate an essential role for Nle1 during organogenesis and in particular during axial development.
Notchless is required for axial skeleton formation in mice.
Beck-Cormier, Sarah; Escande, Marie; Souilhol, Céline; Vandormael-Pournin, Sandrine; Sourice, Sophie; Pilet, Paul; Babinet, Charles; Cohen-Tannoudji, Michel
Maintenance of cell survival is essential for proper embryonic development. In the mouse, Notchless homolog 1 (Drosophila) (Nle1) is instrumental for survival of cells of the inner cell mass upon implantation. Here, we analyze the function of Nle1 after implantation using the Meox2(tm1(cre)Sor) mouse that expresses the Cre recombinase specifically in the epiblast at E5.5. First, we find that NLE1 function is required in epiblast cells, as Nle1-deficient cells are rapidly eliminated. In this report, we also show that the Meox2(Cre) transgene is active in specific tissues during organogenesis. In particular, we detect high Cre expression in the vertebral column, ribs, limbs and tailbud. We took advantage of this dynamic expression profile to analyze the effects of inducing mosaic deletion of Nle1 in the embryo. We show that Nle1 deletion in this context, results in severe developmental anomalies leading to lethality at birth. Mutant embryos display multiple developmental defects in particular during axial skeletal formation. We also provide evidence that axial defects are due to an increase in apoptotic cell death in the somite at E9.5. These data demonstrate an essential role for Nle1 during organogenesis and in particular during axial development.
Observed Incidence of Uveitis Following Certolizumab Pegol Treatment in Patients With Axial Spondyloarthritis
Rudwaleit, M.; Rosenbaum, J. T.; Landewé, R.; Marzo-Ortega, H.; Sieper, J.; van der Heijde, D.; Davies, O.; Bartz, H.; Hoepken, B.; Nurminen, T.; Deodhar, A.
Axial spondyloarthritis (axial SpA) is characterized by inflammation of the spine and sacroiliac joints and can also affect extraarticular sites, with the most common manifestation being uveitis. Here we report the incidence of uveitis flares in axial SpA patients from the RAPID-axSpA trial,
Experimental Study of Axially Tension Cold Formed Steel Channel Members
Apriani, Widya; Lubis, Fadrizal; Angraini, Muthia
Experimental testing is commonly used as one of the steps to determine the cause of the collapse of a building structure. The collapse of structures can be due to low quality materials. Although material samples have passed laboratory tests and the existing technical specifications have been met but there may be undetected defects and known material after failure. In this paper will be presented Experimental Testing of Axially Tension Cold Formed Steel Channel Members to determine the cause of the collapse of a building roof truss x in Pekanbaru. Test of tensile strength material cold formed channel sections was performed to obtain the main characteristics of Cold Formed steel material, namely ultimate tensile strength loads that can be held by members and the yield stress possessed by channel sections used in construction. Analysis of axially tension cold formed steel channel section presents in this paper was conducted through experimental study based on specificationsAnnualBook of ASTM Standards: Metal Test methods and Analitical Procedures, Section 3 (1991). The result of capacity loads experimental test was compared with design based on SNI 03-7971-2013standard of Indonesia for the design of cold formed steel structural members. The results of the yield stress of the material will be seen against the minimum allowable allowable stress range. After the test, the percentace of ultimate axial tension capacity theory has a result that is 16.46% larger than the ultimate axial tension capacity experimental. When compared with the load that must be borne 5.673 kN/m it can be concluded that 2 specimens do not meet. Yield stress of member has fulfilled requirement that wass bigger than 550 MPa. Based on the curve obtained ultimate axial tension capacity theory, results greater than experimental. The greatest voltage value (fu) is achieved under the same conditions as its yield stress. For this specimen with a melting voltage value fy = 571.5068 MPa has fulfilled the
Design and axial optimization of nuclear fuel for BWR reactors
International Nuclear Information System (INIS)
Garcia V, M.A.
In the present thesis, the modifications made to the axial optimization system based on Tabu Search (BT) for the axial design of BWR fuel type are presented, developed previously in the Nuclear Engineering Group of the UNAM Engineering Faculty. With the modifications what is mainly looked is to consider the particular characteristics of the mechanical design of the GE12 fuel type, used at the moment in the Laguna Verde Nucleo electric Central (CNLV) and that it considers the fuel bars of partial longitude. The information obtained in this thesis will allow to plan nuclear fuel reloads with the best conditions to operate in a certain cycle guaranteeing a better yield and use in the fuel burnt, additionally people in charge in the reload planning will be favored with the changes carried out to the system for the design and axial optimization of nuclear fuel, which facilitate their handling and it reduces their execution time. This thesis this developed in five chapters that are understood in the following way in general: Chapter 1: It approaches the basic concepts of the nuclear energy, it describes the physical and chemical composition of the atoms as well as that of the uranium isotopes, the handling of the uranium isotope by means of the nuclear fission until arriving to the operation of the nuclear reactors. Chapter 2: The nuclear fuel cycle is described, the methods for its extraction, its conversion and its enrichment to arrive to the stages of the nuclear fuel management used in the reactors are described. Beginning by the radial design, the axial design and the core design of the nuclear reactor related with the fuel assemblies design. Chapter 3: the optimization methods of nuclear fuel previously used are exposed among those that are: the genetic algorithms method, the search methods based on heuristic rules and the application of the tabu search method, which was used for the development of this thesis. Chapter 4: In this part the used methodology to the
Experimental Studies on Strength Behaviour of Notched Glass/Epoxy Laminated Composites under Uni-axial and Bi-axial Loading
Guptha, V. L. Jagannatha; Sharma, Ramesh S.
The use of FRP composite materials in aerospace, aviation, marine, automotive and civil engineering industry has increased rapidly in recent years due to their high specific strength and stiffness properties. The structural members contrived from such composite materials are generally subjected to complex loading conditions and leads to multi-axial stress conditions at critical surface localities. Presence of notches, much required for joining process of composites, makes it further significant. The current practice of using uni-axial test data alone to validate proposed material models is inadequate leading to evaluation and consideration of bi-axial test data. In order to correlate the bi-axial strengths with the uni-axial strengths of GFRP composite laminates in the presence of a circular notch, bi-axial tests using four servo-hydraulic actuators with four load cells were carried out. To determine the in-plane strength parameters, bi-axial cruciform test specimen model was considered. Three different fibre orientations, namely, 0°, 45°, and 90° are considered with a central circular notch of 10 mm diameter in the present investigation. From the results obtained, it is observed that there is a reduction in strength of 5.36, 2.41 and 13.92% in 0°, 45°, and 90° fibre orientation, respectively, under bi-axial loading condition as compared to that of uni-axial loading in laminated composite.
Electrocardiography-triggered high-resolution CT for reducing cardiac motion artifact. Evaluation of the extent of ground-glass attenuation in patients with idiopathic pulmonary fibrosis
International Nuclear Information System (INIS)
Nishiura, Motoko; Johkoh, Takeshi; Yamamoto, Shuji
The aim of this study was to evaluate the decreasing of cardiac motion artifact and whether the extent of ground-glass attenuation of idiopathic pulmonary fibrosis (IPF) was accurately assessed by electrocardiography (ECG)-triggered high-resolution computed tomography (HRCT) by 0.5-s/rotation multidetector-row CT (MDCT). ECG-triggered HRCT were scanned at the end-diastolic phase by a MDCT scanner with the following scan parameters; axial four-slice mode, 0.5 mm collimation, 0.5-s/rotation, 120 kVp, 200 mA/rotation, high-frequency algorithm, and half reconstruction. In 42 patients with IPF, both conventional HRCT (ECG gating (-), full reconstruction) and ECG-triggered HRCT were performed at the same levels (10-mm intervals) with the above scan parameters. The correlation between percent diffusion of carbon monoxide of the lung (%DLCO) and the mean extent of ground-glass attenuation on both conventional HRCT and ECG-triggered HRCT was evaluated with the Spearman rank correlation coefficient test. The correlation between %DLCO and the mean extent of ground-glass attenuation on ECG-triggered HRCT (observer A: r=-0.790, P<0.0001; observer B: r=-0.710, P<0.0001) was superior to that on conventional HRCT (observer A: r=-0.395, P<0.05; observer B: r=-0.577, P=0.002) for both observers. ECG-triggered HRCT by 0.5 s/rotation MDCT can reduce the cardiac motion artifact and is useful for evaluating the extent of ground-glass attenuation of IPF. (author)
Research on axial thrust of the waterjet pump based on CFD under cavitation conditions
Shen, Z. H.; Pan, Z. Y.
Based on RANS equations, performance of a contra-rotating axial-flow waterjet pump without hydrodynamic cavitation state had been obtained combined with shear stress transport turbulence model. Its cavitation hydrodynamic performance was calculated and analysed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations. The results shows that the cavitation causes axial thrust of waterjet pump to drop. Furthermore, axial thrust and head cavitation characteristic curve is similar. However, the drop point of the axial thrust is postponed by 5.1% comparing with one of head, and the critical point of the axial thrust is postponed by 2.6%.
Research on axial thrust of the waterjet pump based on CFD under cavitation conditions
International Nuclear Information System (INIS)
Shen, Z H; Pan, Z Y
Based on RANS equations, performance of a contra-rotating axial-flow waterjet pump without hydrodynamic cavitation state had been obtained combined with shear stress transport turbulence model. Its cavitation hydrodynamic performance was calculated and analysed with mixture homogeneous flow cavitation model based on Rayleigh-Plesset equations. The results shows that the cavitation causes axial thrust of waterjet pump to drop. Furthermore, axial thrust and head cavitation characteristic curve is similar. However, the drop point of the axial thrust is postponed by 5.1% comparing with one of head, and the critical point of the axial thrust is postponed by 2.6%
Geochemical prospecting in Guiana
International Nuclear Information System (INIS)
Coulomb, R.
During the last few years geochemical prospecting techniques have become common usage in the field of mineral deposit prospecting. The real scope of these methods lies in their use in the prospecting of large areas. The most promising use of the geochemistry and hydro-geochemistry of uranium is in heavily forested tropical territories, with few outcrops, where radiometry is strongly handicapped. (author) [fr
Schmidt, Ulrich; Zank, Horst
In previous models of (cumulative) prospect theory reference-dependence of preferences is imposed beforehand and the location of the reference point is exogenously determined. This paper provides an axiomatization of a new specification of cumulative prospect theory, termed endogenous prospect theory, where reference-dependence is derived from preference conditions and a unique reference point arises endogenously.
Radiologic analysis of hindfoot alignment: Comparison of Méary, long axial, and hindfoot alignment views.
Neri, T; Barthelemy, R; Tourné, Y
Among radiographic views available for assessing hindfoot alignment, the antero-posterior weight-bearing view with metal cerclage of the hindfoot (Méary view) is the most widely used in France. Internationally, the long axial view (LAV) and hindfoot alignment view (HAV) are used also. The objective of this study was to compare the reliability of these three views. The Méary view with cerclage of the hindfoot is as reliable as the LAV and HAV for assessing hindfoot alignment. All three views were obtained in each of 22 prospectively included patients. Intra-observer and inter-observer reliabilities were assessed by having two observers collect the radiographic measurements then computing the intra-class correlation coefficients (ICCs). The intra-observer and inter-observer ICCs were 0.956 and 0.988 with the Méary view, 0.990 and 0.765 with the HAV, and 0.997 and 0.991 with the LAV, respectively. Correlations were far stronger between the LAV and HAV than between each of these and the Méary view. Compared to the LAV and HAV, the Méary view indicated a greater degree of hindfoot valgus. Intra-observer reliability was excellent with both the LAV and HAV, whereas inter-observer reliability was better with the LAV. Excellent reliability was also obtained with the Méary view. Combining the Méary view to obtain a radiographic image of the clinical deformity with the LAV to measure the angular deviation of the hindfoot axis may be useful when assessing hindfoot malalignment. A comparison of the three views in a larger population is needed before clinical recommendations can be made. II, prospective study. Copyright © 2017 Elsevier Masson SAS. All rights reserved.
Renormalization of the axial-vector current in QCD
International Nuclear Information System (INIS)
Chiu, C.B.; Pasupathy, J.; Wilson, S.L.
Following the method of Ioffe and Smilga, the propagation of the baryon current in an external constant axial-vector field is considered. The close similarity of the operator-product expansion with and without an external field is shown to arise from the chiral invariance of gauge interactions in perturbation theory. Several sum rules corresponding to various invariants both for the nucleon and the hyperons are derived. The analysis of the sum rules is carried out by two independent methods, one called the ratio method and the other called the continuum method, paying special attention to the nondiagonal transitions induced by the external field between the ground state and excited states. Up to operators of dimension six, two new external-field-induced vacuum expectation values enter the calculations. Previous work determining these expectation values from PCAC (partial conservation of axial-vector current) are utilized. Our determination from the sum rules of the nucleon axial-vector renormalization constant G/sub A/, as well as the Cabibbo coupling constants in the SU 3 -symmetric limit (m/sub s/ = 0), is in reasonable accord with the experimental values. Uncertainties in the analysis are pointed out. The case of broken flavor SU 3 symmetry is also considered. While in the ratio method, the results are stable for variation of the fiducial interval of the Borel mass parameter over which the left-hand side and the right-hand side of the sum rules are matched, in the continuum method the results are less stable. Another set of sum rules determines the value of the linear combination 7F-5D to be roughly-equal0, or D/(F+D)roughly-equal(7/12). .AE
Test Procedure for Axially Loaded Piles in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina
The test procedure described in the following is used when examining the effects of static or cyclic loading on the skin friction of an axially loaded pile in dense sand. The pile specimen is only loaded in tension to avoid any contribution from the base resistance. The pile dimensions are chosen...... to resemble full scale dimension of piles used in offshore pile foundations today. In this report is given a detailed description of the soil preparation and pile installation procedures as well data acquisition methods....
Bone mineral density in patients with early axial spondyloarthritis
Directory of Open Access Journals (Sweden)
E. E. Gubar
Full Text Available Objective: to study bone mineral density (BMD of the lumbar spine (LS and femoral neck (FN in patients with early axial spondyloarthritis (SpA and to reveal its association with inflammatory disease activity.Subjects and methods. Seventy-three patients aged 18–45 years with inflammatory back pain lasting at least 3 months and not more than 5 years were examined. Axial SpA was diagnosed according to the 2009 ASAS criteria. BASDAI and ASDAS C-reactive protein (CRP values were used to estimate disease activity; BASFI was employed to evaluate functional status. The examination encompassed determination of HLA-B27, X-ray of the pelvis and LS, magnetic resonance imaging (MRI of sacroiliac joints, LS, and hip joints (in the presence of clinical signs of their injuries, densitometry of LS (LI-IV and FN. By taking into account the young age of patients, the Z-score was applied to measure BMD. The latter is considered lower if the Z-score is 1–2 standard deviations (SD in at least one of the segments under study.Results. The median Z-score was -0.7 (-1.3; -0.3 SD for FN and 0.9 (-1.6; -0.5 SD for LS. Reduced BMD in at least one of the segments under study was detected in 13 (17.8% patients: that in LS and FN in 11 (15.1% and 5 (6.8% patients, respectively. Lower BMD was observed in two segments in 3 (4.1% patients. No association was found between lower BMD and age, gender, disease activity (BASDAI, ASDAS, and laboratory inflammatory markers (erythrocyte sedimentation rate (ESR and CRP. A relationship was established between inflammatory changes according to the data of MRI of LS (MRI spondylitis and reduced BMD in the same segment. MRI spondylitis was detected in 8 patients. Five and 3 patients with spondylitis of LS were found to have lower and normal BMD in this segment, respectively. Six out of 65 patients without MRI spondylitis in LS had its reduced BMD and the remaining (n=59 patients had its normal BMD (p=0.0014.Conclusion. There was an
Axial gap formation in P.W.R. fuel pins
International Nuclear Information System (INIS)
Roberts, G.; Jones, K.W.
The potential mechanisms of axial gap formation in PWR fuel pins are examined analytically and also using evidence from post-irradiation examination (p.i.e.) investigation. It is concluded that fuel and cladding cannot remain in contact during densification and so the settling of of the fuel stack, which forms the gaps, must be prevented by such things as asperities in the cladding, fuel chips or tilted pellets. Examples from the p.i.e. examination programme are used to support this conclusion. (author)
Momentum distribution at great depths when electron axial channeling
International Nuclear Information System (INIS)
Khokonov, M.Kh.; Tuguz, F.K.
The electron distribution in momenta during axial channeling in thick monocrystals in great depths is estimated. The estimate was carried out with respect to the fact that due to diffusion the angular momentum of the electron can change only in a limited region of phase space and that multiple scattering only takes place on thermal oscillations of nuclei of the crystal lattice. It is shown that in thick monocrystals the distribution in momenta can be considered uniform on the greater part of the way of channeled electrons which can simplity the qualitative consideration of spectral-angular characteristics forming during this radiation
Evaluation of axial fission gas transport in power ramping experiments
International Nuclear Information System (INIS)
Kinoshita, Motoyasu
The LINUS code calculates advective and diffusional transport of fission gas towards an upper plenum through the pellet-cladding gap. The basic equations were modified for analyzing a multi-component gas mixture in the gap and also for dealing with opening and/or closing of the gap, which induces additional axial gas flow. Analysis of the Petten ramp experiment shows that helium pressurization is effective in suppressing an ascending rate of fission gas concentration. After the maximum concentration is achieved through power ramping, the gas concentration could be described by a steady state analytical solution which does not depend on the filling gas pressure. (author)
Axial Permanent Magnet Generator for Wearable Energy Harvesting
DEFF Research Database (Denmark)
Högberg, Stig; Sødahl, Jakob Wagner; Mijatovic, Nenad
An increasing demand for battery-free electronics is evident by the rapid increase of wearable devices, and the design of wearable energy harvesters follows accordingly. An axial permanent magnet generator was designed to harvest energy from human body motion and supplying it to a wearable......W, respectively) with an iron yoke is subject to losses that exceed the realistic input power, and was therefore deemed infeasible. A generator without the iron yoke was concluded to perform well as a wearable energy harvester. An experimental investigation of a prototype revealed an output power of almost 1 m...
Time Dependent and Steady Uni-axial Elongational Viscosity
DEFF Research Database (Denmark)
Nielsen, Jens K.; Rasmussen, Henrik Koblitz; Hassager, Ole
Here we present measurements of transient and steady uni-axial elongational viscosity, using the Filament Stretching Rheometer1 or FSR1 (see Fig. 1) of the following melts: Four narrow MMD polystyrene (PS) samples with weight-average molar mass Mw in the range of 50k to 390k. Three different bi......-disperse samples, mixed from the narrow MMD PS. Two low-density polyethylene (LDPE) melts (Lupolen 1840D and 3020D). A steady-state viscosity was kept for 1-2.5 Hencky strain units in all measurements....
Axial gravitational waves in FLRW cosmology and memory effects
Kulczycki, Wojciech; Malec, Edward
We show initial data for gravitational axial waves that are twice differentiable but that are not C2. They generate wave pulses that interact with matter in the radiation cosmological era. This forces the radiation matter to rotate. This rotation is permanent—it persists after the passage of the gravitational pulse. The observed inhomogeneities of the cosmic microwave background radiation put a bound onto discontinuities of superhorizon metric perturbations. We explicitly show that a class of smooth initial metrics that are at least C2 gives rise to gravitational wave pulses that do not interact with the background during the radiation epoch.
Axially symmetric reconstruction of plasma emission and absorption coefficients
International Nuclear Information System (INIS)
Yang Lixin; Jia Hui; Yang Jiankun; Li Xiujian; Chen Shaorong; Liu Xishun
A layered structure imaging model is developed in order to reconstruct emission coefficients and absorption coefficients simultaneously, in laser fusion core plasma diagnostics. A novel axially symmetric reconstruction method that utilizes the LM (Levenberg-Marquardt) nonlinear least squares minimization algorithm is proposed based on the layered structure. Numerical simulation results demonstrate that the proposed method is sufficiently accurate to reconstruct emission coefficients and absorption coefficients, and when the standard deviation of noise is 0.01, the errors of emission coefficients and absorption coefficients are 0.17, 0.22, respectively. Furthermore, this method could perform much better on reconstruction effect compared with traditional inverse Abel transform algorithms. (authors)
On the equivalence between the Schwinger and axial models
International Nuclear Information System (INIS)
Souza Dutra, A. de.
We show the equivalence between the Schwinger and axial models, in the sense that all Green's functions of one model can be obtained from those of the other, and that both models have the same effective Lagrangian density (and so they have equal partition functions associated with them). In particular, we show that the two models have the same chiral anomaly. Finally it is demonstrated that the Schwinger model can keep gauge invariance for an arbitrary mass, dispensing with an additional gauge group integration. (author)
Axial and Radial Gas Holdup in Bubble Column Reactor
International Nuclear Information System (INIS)
Wagh, Sameer M.; Ansari, Mohashin E Alan; Kene, Pragati T.
Bubble column reactors are considered the reactor of choice for numerous applications including oxidation, hydrogenation, waste water treatment, and Fischer-Tropsch (FT) synthesis. They are widely used in a variety of industrial applications for carrying out gas-liquid and gas-liquid-solid reactions. In this paper, the computational fluid dynamics (CFD) model is used for predicting the gas holdup and its distribution along radial and axial direction are presented. Gas holdup increases linearly with increase in gas velocity. Gas bubbles tends to concentrate more towards the center of the column and follows a wavy path
Axial dispersion via shear-enhanced diffusion in colloidal suspensions
Griffiths, I. M.
The familiar example of Taylor dispersion of molecular solutes is extended to describe colloidal suspensions, where the fluctuations that contribute to dispersion arise from hydrodynamic interactions. The generic scheme is illustrated for a suspension of particles in a pressure-driven pipe flow, with a concentration-dependent diffusivity that captures both the shear-induced and Brownian contributions. The effect of the cross-stream migration via shear-induced diffusion is shown to dramatically reduce the axial dispersion predicted by classical Taylor dispersion for a molecular solute. Analytic and numerical solutions are presented that illustrate the effect of the concentration dependence of this nonlinear hydrodynamic mechanism. Copyright © EPLA, 2012.
Characteristics of axial splits in failed BWR fuel rods
International Nuclear Information System (INIS)
Lysell, G.; Grigoriev, V.
Secondary cladding defects in BWR fuel sometimes have the shape of long axial cracks or ''splits''. Due to the large open UO 2 surfaces exposed to the water, fission product and UO 2 release to the coolant can reach excessive levels leading to forced shut downs to remove the failed fuel rods. A number of such fuel rods have been examined in Studsvik over the last 10 years. The paper describes observations from the PIE of long cracks and discusses the driving force of the cracks. Details such as starting cracks, macroscopic and microscopic fracture surface appearance, cross sections of cracks, hydride precipitates, location and degree of plastic deformation are given. (author)
Numerical Study of Transonic Axial Flow Rotating Cascade Aerodynamics – Part 1: 2D Case
Directory of Open Access Journals (Sweden)
Irina Carmen ANDREI
Full Text Available The purpose of this paper is to present a 2D study regarding the numerical simulation of flow within a transonic highly-loaded rotating cascade from an axial compressor. In order to describe an intricate flow pattern of a complex geometry and given specific conditions of cascade's loading and operation, an appropriate accurate flow model is a must. For such purpose, the Navier-Stokes equations system was used as flow model; from the computational point of view, the mathematical support is completed by a turbulence model. A numerical comparison has been performed for different turbulence models (e.g. KE, KO, Reynolds Stress and Spallart-Allmaras models. The convergence history was monitored in order to focus on the numerical accuracy. The force vector has been reported in order to express the aerodynamics of flow within the rotating cascade at the running regime, in terms of Lift and Drag. The numerical results, expressed by plots of the most relevant flow parameters, have been compared. It comes out that the selecting of complex flow models and appropriate turbulence models, in conjunction with CFD techniques, allows to obtain the best computational accuracy of the numerical results. This paper aims to carry on a 2D study and a prospective 3D will be intended for the same architecture.
Laminoplasty Does not Lead to Worsening Axial Neck Pain in the Properly Selected Patient With Cervical Myelopathy: A Comparison With Laminectomy and Fusion.
Stephens, Byron F; Rhee, John M; Neustein, Thomas M; Arceo, Rafael
Retrospective cohort study of prospectively collected data. To determine if laminoplasty (LP) is associated with worsening axial neck pain in patients with multilevel cervical myelopathy, and to compare neck pain, clinical outcomes, and radiographic measures in a group undergoing laminectomy and fusion (LF). Postoperative new or worsening axial neck pain is commonly cited as a major disadvantage of laminoplasty. However, there remains a paucity of corroborative data from large series. Following institutional review board approval, we reviewed the medical records, radiographs, and prospective clinical outcomes database of 85 patients undergoing LP and 52 patients undergoing LF for cervical myelopathy with minimum 1-year radiographic follow-up and average clinical follow-up of 18.5 months. LP was performed in those with neutral to lordotic C2-7 alignment and who did not complain of diffuse axial pain. Otherwise, LF was performed. Clinical outcomes included visual analogue score (VAS)-neck pain, VAS-total pain, neck disability index (NDI), short form 36, modified Japanese Orthopaedic Association (mJOA), and several radiographic parameters. VAS-neck did not worsen in LP (-0.2, P = 0.54) and did improve in LF (-2.0, P = 0.0013). VAS-total improved significantly in both groups (LF -1.04 ± 0.52, P = 0.05; LP -1.4 ± 0.51, P = 0.008). NDI improved in both groups, but was significant in only LP (LP decreased 6.79 ± 2.25, P = 0.0032; LF decreased 4.01 ± 3.05, P = 0.19). mJOA scores improved significantly in both groups (LP improved 2.89 ± 0.27, P cervical lordosis in both groups that was significant in LP (LP 2.92° loss, P = 0.0181; LF 1.25° loss, P = 0.53). In a carefully selected group of myelopathic patients without significant diffuse axial pain preoperatively and appropriate sagittal alignment, laminoplasty did not lead to worsening axial neck pain, and it was associated with significant improvements in other
Research on a novel axial-flux magnetic-field-modulated brushless double-rotor machine with low axial force and high efficiency
Directory of Open Access Journals (Sweden)
Chengde Tong
Full Text Available The axial-flux magnetic-field-modulated brushless double-rotor machine (MFM-BDRM is a possible alternative as a power-split device for hybrid electric vehicles (HEVs. However, the existence of large axial force may lead to assembly problems and rich inner air-gap harmonics could result in high PM loss and low efficiency. This paper proposes a novel axial-flux MFM-BDRM with improved PM rotor structure. 2-D analytical method to predict the magnetic-field distribution of the proposed MFM-BDRM is developed and the design procedure of the proposed machine is illustrated. The impact of key geometrical parameters on axial force and torque is investigated. To evaluate the advantage of the proposed machine, a comparison is made with a conventional one with respect to electromagnetic performances. Results show that the proposed machine is effective in reducing PM eddy loss and axial force by 60% and 35%, respectively.
Numerical simulation of the tip clearance flow in axial turbomachinery; Numerische Simulation der Stroemung im radialen Schaufelspalt axialer Turbomaschinen
Energy Technology Data Exchange (ETDEWEB)
Melake, A [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Koeln (Germany). Inst. fuer Antriebstechnik
A computer program has been developed to calculate the three-dimensional tip leakage flow in axial turbomachinery based on the Navier-Stokes equation. This program has been applied to investigate the leakage flow within the gap between the blade fip and casing in an annular compressor cascade. A block structured computational mesh has been used in order to resolve the flow details within the gap and the passage flow. Flow characteristics like boundary layer separation, vortex genesis and interaction of the leakage flow with the secondary flow have been investigated and compared with existing experimental data. By varying the incidence angle and the tip gap the above mentioned flow phenomena have been analysed in an annular compressor cascade and a shrouded propfan rotor respectively. Furthermore, the relationship between the total pressure loss, the axial velocity deficit and the divergence of the tip leakage vortex has been investigated. Streamlines, limited streamlines and the critical point theory have been used extensively to analyse the boundary layer separation on the casing and its roll up to form the tip clearance vortex. (orig.). 59 figs., 3 tabs., 110 refs. [Deutsch] Es wurde ein Rechenprogramm zur Berechnung der dreidimensionalen Spaltstroemung im radialen Schaufelspalt axialer Turbomaschinen auf der Basis der Navier-Stokes`schen Gleichungen entwickelt und angewendet. Um die Stroemung innerhalb des Spaltes und der Schaufelpassage besser aufloesen zu koennen, wurde eine blockstrukturierte Netztopologie verwendet. Stroemungseigenschaften wie Grenzschichtabloesung, Entstehung des Spaltwirbels, Interaktion der Spaltstroemung mit der Sekundaerstroemung werden untersucht und mit vorhandenen experimentellen Daten verglichen. Im weiteren werden durch Variation der Inzidenz und der Spaltweite die oben genannten Stroemungsphaenomene an einem axialen Verdichterringgitter und an einem ummantelten Propfan analysiert. Ferner werden die Korrelation zwischen
Flow measurements using noise signals of axially displaced thermocouples
Energy Technology Data Exchange (ETDEWEB)
Kozma, R.; Hoogenboom, J.E. (Interuniversitair Reactor Inst., Delft (Netherlands))
Determination of the flow rate of the coolant in the cooling channels of nuclear reactors is an important aspect of core monitoring. It is usually impossible to measure the flow by flowmeters in the individual channels due to the lack of space and safety reasons. An alternative method is based on the analysis of noise signals of the available in-core detectors. In such a noise method, a transit time which characterises the propagation of thermohydraulic fluctuations (density or temperature fluctuations) in the coolant is determined from the correlation between the noise signals of axially displaced detectors. In this paper, the results of flow measurements using axially displaced thermocouples in the channel wall will be presented. The experiments have been performed in a simulated MRT-type fuel assembly located in the research reactor HOR of the Interfaculty Reactor Institute, Delft. It was found that the velocities obtained via temperature noise correlation methods are significantly larger than the area-averaged velocity in the single-phase coolant flow. Model calculations show that the observed phenomenon can be explained by effects due to the radial velocity distribution in the channel. (author).
Axial design of fuel for BWRs using neural networks
International Nuclear Information System (INIS)
Ortiz, J.J.; Castillo, A.; Montes, J.L.; Perusquia, R.
In this work a new system of axial optimization of fuel is presented based on a recurrent multi state neural net called RENODC. They are described with detail the main characteristics of this type of neural net (architecture, energy function and actualization of neural states) and like was adapted to the assemble design of nuclear fuel. The fuel design is proven by means of a fuel recharge and pre determined control rod patterns. By this way a good axial fuel design one has, when the thermal limits are fulfilled along the cycle, the reactor stays critic and at least the wanted longitude of the cycle is reached; also the margin of in cold turned off is verified. The assemble of fuel created with RENODC it is substituted by a recharge assemble and it is sought to verify that the energy requirements and aspects of safety are completed. The used cycle corresponds to a balance cycle of 18 months that it can be applied to the Laguna Verde Nucleo electric Central. The tests demonstrate the effectiveness of the system to reach satisfactory results in times of CPU of around 4 hours. This way, it could be proven that the design proposed with a lightly superior enrichment to that of the substituted design, fulfills the energy requirements. In later stages of this project this system will be coupled to the other optimization modules that are already had. (Author)
Competition between modes with different axial structures in gyrotrons
International Nuclear Information System (INIS)
Khutoryan, Eduard M.; Nusinovich, Gregory S.; Sinitsyn, Oleksandr V.
This study was motivated by some experiments in which it was found that during the voltage rise, instead of expected excitation of a high-frequency parasitic mode, the excitation of a lower-frequency parasitic mode takes place in a certain range of voltages. For explaining this fact, the dependence of start currents of possible competing modes on the beam voltage was carried out in the cold-cavity approximation and by using the self-consistent approach. It was found that in the case of cavities, which consist of the combination of a section of constant radius waveguide and a slightly uptapered waveguide, these two approaches yield completely different results. Thus, experimentally observed excitation of the low-frequency parasitic mode can be explained by the self-consistent modification of the axial profile of the excited field, which has strong influence on the diffractive quality factor of competing modes. This modification is especially pronounced in the case of excitation of modes with many axial variations which can be excited in the region of beam interaction with the backward-wave component of such modes
Design and analysis of miniature tri-axial fluxgate magnetometer
Zhi, Menghui; Tang, Liang; Qiao, Donghai
The detection technology of weak magnetic field is widely used in Earth resource survey and geomagnetic navigation. Useful magnetic field information can be obtained by processing and analyzing the measurement data from magnetic sensors. A miniature tri-axial fluxgate magnetometer is proposed in this paper. This miniature tri-axial fluxgate magnetometer with ring-core structure has a dynamic range of the Earth's field ±65,000 nT, resolution of several nT. It has three independent parts placed in three perpendicular planes for measuring three orthogonal magnetic field components, respectively. A field-programmable gate array (FPGA) is used to generate stimulation signal, analog-to-digital (A/D) convertor control signal, and feedback digital-to-analog (D/A) control signal. Design and analysis details are given to improve the dynamic range, sensitivity, resolution, and linearity. Our prototype was measured and compared with a commercial standard Magson fluxgate magnetometer as a reference. The results show that our miniature fluxgate magnetometer can follow the Magson's change trend well. When used as a magnetic compass, our prototype only has ± 0.3∘ deviation compared with standard magnetic compass.
Axial and parity anomalies and vacuum charge: A direct approach
International Nuclear Information System (INIS)
Boyanovsky, D.; Blankenbecler, R.
We study the axial and parity anomalies in Abelian gauge theories using the direct yet intuitive approach of counting the relative number of states of one chirality with respect to the other. A fundamental gauge-invariant quantity, the determinantal ratio, is introduced for this purpose. We find that the number of states is conserved and that the gauge fields differentially phase shift states of opposite chirality at infinite energies. This implies a relative flow of states at very large energies which must be compensated by a rearrangement of the density of states at finite energies. We then derive a sum rule which yields two alternative formulas for the index of a Dirac operator. One expresses the index in terms of its high-energy behavior, and the other in terms of the low-energy properties; these are the ''zero modes'' of definite chirality. Two examples are worked out in detail to clarify our general result. The physics of the axial anomaly is shown to translate into that of the parity anomaly in 2+1 dimensions, in which parity and chirality have interchanged roles. We also analyze the vacuum charge in regard to its high- and low-energy origin. The possibility of spectral flow is formulated and briefly discussed. In short, we provide a physical interpretation of certain mathematical indices, relate them to an extended version of Levinson's theorem of potential scattering, and simplify their evaluation
Axial Ge/Si nanowire heterostructure tunnel FETs.
Energy Technology Data Exchange (ETDEWEB)
Dayeh, Shadi A. (Los Alamos National Laboratory); Gin, Aaron V.; Huang, Jian Yu; Picraux, Samuel Thomas (Los Alamos National Laboratory)
Axial Ge/Si heterostructure nanowires (NWs) allow energy band-edge engineering along the axis of the NW, which is the charge transport direction, and the realization of asymmetric devices for novel device architectures. This work reports on two significant advances in the area of heterostructure NWs and tunnel FETs: (i) the realization of 100% compositionally modulated Si/Ge axial heterostructure NWs with lengths suitable for device fabrication and (ii) the design and implementation of Schottky barrier tunnel FETs on these NWs for high-on currents and suppressed ambipolar behavior. Initial prototype devices with 10 nm PECVD SiN{sub x} gate dielectric resulted in a very high current drive in excess of 100 {micro}A/{micro}m (I/{pi}D) and 10{sup 5} I{sub on}/I{sub off} ratios. Prior work on the synthesis of Ge/Si axial NW heterostructures through the VLS mechanism have resulted in axial Si/Si{sub 1-x}Ge{sub x} NW heterostructures with x{sub max} {approx} 0.3, and more recently 100% composition modulation was achieved with a solid growth catalyst. In this latter case, the thickness of the heterostructure cannot exceed few atomic layers due to the slow axial growth rate and concurrent radial deposition on the NW sidewalls leading to a mixture of axial and radial deposition, which imposes a big challenge for fabricating useful devices form these NWs in the near future. Here, we report the VLS growth of 100% doping and composition modulated axial Ge/Si heterostructure NWs with lengths appropriate for device fabrication by devising a growth procedure that eliminates Au diffusion on the NW sidewalls and minimizes random kinking in the heterostructure NWs as deduced from detailed microscopy analysis. Fig. 1 a shows a cross-sectional SEM image of epitaxial Ge/Si axial NW heterostructures grown on a Ge(111) surface. The interface abruptness in these Ge/Si heterostructure NWs is of the order of the NW diameter. Some of these NWs develop a crystallographic kink that is {approx
Axial U(1) current in Grabowska and Kaplan's formulation
Hamada, Yu; Kawai, Hikaru
Recently, Grabowska and Kaplan [Phys. Rev. Lett. 116, 211602 (2016); Phys. Rev. D 94, 114504 (2016)] suggested a nonperturbative formulation of a chiral gauge theory, which consists of the conventional domain-wall fermion and a gauge field that evolves by gradient flow from one domain wall to the other. We introduce two sets of domain-wall fermions belonging to complex conjugate representations so that the effective theory is a 4D vector-like gauge theory. Then, as a natural definition of the axial-vector current, we consider a current that generates simultaneous phase transformations for the massless modes in 4 dimensions. However, this current is exactly conserved and does not reproduce the correct anomaly. In order to investigate this point precisely, we consider the mechanism of the conservation. We find that this current includes not only the axial current on the domain wall but also a contribution from the bulk, which is nonlocal in the sense of 4D fields. Therefore, the local current is obtained by subtracting the bulk contribution from it.
Pit above the lesser tuberosity in axial view radiography.
Cho, Jae-Ho; Han, Kyeong-Jin; Lee, Doo-Hyung; Chung, Nam-Su; Park, Do Young
This study examined the relationship between the presence of a pit above the lesser tuberosity on axial view radiographs and rotator cuff tears and compared the demographic data between groups according to the presence of a pit above the lesser tuberosity. The hypothesis of this study was that the radiographic finding of a pit above the lesser tuberosity is related to rotator cuff tears. For 112 patients with a symptomatic rotator cuff tear, plain radiographs of the symptomatic shoulder (tear side radiographs) and plain radiographs of the asymptomatic contralateral shoulder (no-tear side radiographs) were assessed. Seventeen radiological findings, including a pit above the lesser tuberosity, osteophytes, subchondral cysts, and sclerosis, were recorded by one blinded observer. Demographic data such as age, duration of symptoms, sex, arm dominance, smoking history, trauma history, American Shoulder and Elbow Surgeons score, Constant score, and involved tendon were collected. A pit above the lesser tuberosity was noted on tear side radiographs of 40 patients (35.7 %) and on the no-tear side radiographs of 27 patients (24.1 %), representing a significant difference (P = 0.040). A pit associated with a rotator cuff tear was observed more often in the dominant arm (P = 0.040) and more often in patients with less previous trauma (P = 0.024). A pit above the lesser tuberosity on axial view radiography was associated with a rotator cuff tear and occurred more often in the dominant arm of patients who had no trauma history. Prognostic study, Level III.
Axial anomaly and index theorem for Dirac-Kaehler fermions
International Nuclear Information System (INIS)
Fonseca Junior, C.A.L. da.
Some aspects of topological influence on gauge field theory are analysed, considering the geometry and differential topology methods. A review of concepts of differential forms, fibered spaces, connection and curvature, showing an interpretation of gauge theory in this context, is presented. The question of fermions, analysing in details the Dirac-Kaehler which fermionic particle is considered a general differential form, is studied. It is shown how the explicit expressions in function of the Dirac spinor components vary with the Dirac matrix representation. The Dirac-Kahler equation contains 4 times (in 4 dimensions) the Dirac equation, each particle being associated an ideal at left of the algebra of general differential forms. These ideals and the SU(4) symmetry among them are also studied on the point of view of spinors and, the group of reduction to one of the ideals is identified as the Cartan subalgebra of this SU(4). Finally, the axial anomaly is calculated through the functional determinant given by the Dirac-Kaehler operator. The regularization method is the Seeley's coefficients. From that results a comparison of the index theorems for the twisted complexes of signature and spin, which proportionality is given by the number of the algebra ideals contained in the Dirac-Kaehler equation and which also manifests in the respective axial anomaly equations. (L.C.) [pt
Axial length of atomic bomb survivors in Nagasaki
International Nuclear Information System (INIS)
Wakiyama, Harumi; Kishikawa, Yasuhiro; Imamura, Naoki; Amemiya, Tsugio
We reviewed a series of 778 patients who had cataract surgery during the past 4 years at the Nagasaki Atomic Bomb Memorial Hospital. We evaluated the history of exposure to radiation by atomic bomb in 1945, axial length and state of refraction. All were born before 1945. The series comprised 263 males and 515 females. Their ages averaged 76.5±8.6 years. History of exposure to radiation was present in 356 patients. The remaining 422 patients served as control. There was no difference in the type of cataract between the two groups. High myopia was present in 11 irradiated patients (3.2%) and in 24 patients in the control group (6.0%). The difference was not significant (p=0.083). There was no high myopia among 24 patients who were aged 18 years or less at the time of radiation and who were within 2 km from the epicenter. No difference was present regarding the axial length between the two groups or between both sexes. The present result is not definitive because ''irradiated group'' would include those with little or no exposure and because precise data has not been available about the dosis of radiation. (author)
Vibration mechanism of fuel rod in axial flow
International Nuclear Information System (INIS)
Kang, Heung Seok; Yoon, Kyung Ho; Kim, Hyung Kyu; Song, Kee Nam
This is a review on the previous researches for the vibration of fuel rod induced by axial flow. The analysis methods are classified into three categories accordingly as the researchers postulate the vibration to be self-excited, forced and parametric; the self-excited mechanism by Burgreen and Quinn, the forced one by Reavis, Gorman, kanazawa, and S. Chen, and the parametric one by Y. Chen. Quinn supposed that the centrifugal force by flow exaggerated the natural bow in the cylinder, and the flexural force by it diminished the bow by turns; this interactive motion leaded cylinder to vibration. The supporters to the forced mechanism considered the forces arising from pressure perturbation within the boundary layers as vibrating sources. Y. Chen insisted that the cylinder could only be excited to vibration in resonance by the small oscillation of mean flow velocity. The previous studies were based on the simple boundary conditions such as hinged-hinged or fixed-fixed single span. Therefore, for the more accurate prediction of the fuel rod vibration in reactor, the further studies need to reflect the actual boundary conditions of the fuel rod like axial force and continuous supports by grids. (author). 25 refs
The effects of initial rise and axial loads on MEMS arches
Tella, Sherif Adekunle
Arch microbeams have been utilized and proposed for many uses over the past few years due to their large tunability and bistability. However, recent experimental data have shown different mechanical behavior of arches when subjected to axial loads. This paper aims to investigate in depth the influence of the competing effects of initial rise and axial loads on the mechanical behavior of micromachined arches; mainly their static deflection and resonant frequencies. Based on analytical solutions, the static response and eigenvalue problems are analyzed for various values of initial rises and axial loads. Universal curves showing the variation of the first three resonance frequencies of the arch are generated for various values of initial rise under both tensile and compressive axial loads. This study shows that increasing the tensile or compressive axial loads for different values of initial rise may lead to either increase in the stiffness of the beam or initial decrease in the stiffness, which later increases as the axial load is increased depending on the dominant effect of the initial rise of the arch and the axial load. The obtained universal curves represent useful design tools to predict the tunability of arches under axial loads for various values of initial rises. The use of the universal curves is demonstrated with an experimental case study. Analytical formulation is developed to predict the point of minimum where the trend of the resonance frequency versus axial loads changes qualitatively due to the competing effects of axial loads and initial curvature.
Psychophysiology of prospective memory.
Rothen, Nicolas; Meier, Beat
Prospective memory involves the self-initiated retrieval of an intention upon an appropriate retrieval cue. Cue identification can be considered as an orienting reaction and may thus trigger a psychophysiological response. Here we present two experiments in which skin conductance responses (SCRs) elicited by prospective memory cues were compared to SCRs elicited by aversive stimuli to test whether a single prospective memory cue triggers a similar SCR as an aversive stimulus. In Experiment 2 we also assessed whether cue specificity had a differential influence on prospective memory performance and on SCRs. We found that detecting a single prospective memory cue is as likely to elicit a SCR as an aversive stimulus. Missed prospective memory cues also elicited SCRs. On a behavioural level, specific intentions led to better prospective memory performance. However, on a psychophysiological level specificity had no influence. More generally, the results indicate reliable SCRs for prospective memory cues and point to psychophysiological measures as valuable approach, which offers a new way to study one-off prospective memory tasks. Moreover, the findings are consistent with a theory that posits multiple prospective memory retrieval stages.
Approaches to ultra-low radiation dose coronary artery calcium scoring based on 3rd generation dual-source CT : A phantom study
McQuiston, Andrew D.; Muscogiuri, Giuseppe; Schoepf, U. Joseph; Meinel, Felix G.; Canstein, Christian; Varga-Szemes, Akos; Cannao, Paola M.; Wichmann, Julian L.; Allmendinger, Thomas; Vliegenthart, Rozemarijn; De Cecco, Carlo N.
Objectives: To investigate to what extent 3rd generation dual-source computed tomography (DSCT) can reduce radiation dose in coronary artery calcium scoring. Methods: Image acquisition was performed using a stationary calcification phantom. Prospectively electrocardiogram (ECG)-triggered 120 kV
Interconnection between several eye biomechanical and biometric parameters in children with axial and refractive mild myopia
Directory of Open Access Journals (Sweden)
T. Ye. Tsybulskaya
Full Text Available Aim – to study the relationship of biometric and biomechanical indicators of corneoscleral capsule of the eye in children with axial and refractive mild myopia. Materials and methods. Axial myopia was diagnosed in 32 children (64 eyes, refractive myopia – 18 (36 eyes. The control group – 16 children without ophthalmic diseases (32 eyes. Eye examination: visometry, automated refractometry, biomicroscopy, ophthalmoscopy, determination of the axial length of the eyeball and corneal hysteresis. Results. Significant differences were determined in the indicators of dioptric power of the cornea: 42.2 dpt in patients with axial and 44.7 dpt with refractive myopia (p<0.05, and also difference between patients with refractive myopia and the control group, in which the diopter power of cornea was 42.6 (p<0.05. There are also significant differences in the indicators of the axial length of eyes between axial and refractive myopia – 24.5±0.64 mm and 23.1±0.43 mm (p<0.05. Significant difference with the control group in the axial length marked only in eyes with axial myopia 22.7±0.33 mm and 24.5±0.64 mm, respectively (p<0.05. Corneal hysteresis determined significantly reduced on eyes with both the axial and refractive myopia, which was significantly lower than in the indicators of emmetropic eyes of the control group 13.7 (p<0.05. Corneal hysteresis is inversely related to the axial length of the eyeball: in patients with axial myopia r -0.32, p<0.05; with refractive myopia r -0.36, p<0.05. Сorrelation between diopter power of cornea and axial length of the eyeball: r -0.53, р<0.05 in eyes with axial myopia and r -0.42, p<0.05 refractive myopia. Comparative analysis showed no significant differences between the corneal hysteresis, the axial length of the eye and the spherical component of myopia. Conclusions. In patients with axial and refractive mild myopia corneal hysteresis is reduced on average in 1.2 and 1.1 times, in comparison with
Axial design of fuel for BWRs using neural networks; Diseno axial de combustible para BWRs usando redes neuronales
Energy Technology Data Exchange (ETDEWEB)
Ortiz, J.J.; Castillo, A.; Montes, J.L.; Perusquia, R. [ININ, Carretera Mexico-Toluca s/n, 52750 La Marquesa, Ocoyoacac, Estado de Mexico (Mexico)]. e-mail: email@example.com
In this work a new system of axial optimization of fuel is presented based on a recurrent multi state neural net called RENODC. They are described with detail the main characteristics of this type of neural net (architecture, energy function and actualization of neural states) and like was adapted to the assemble design of nuclear fuel. The fuel design is proven by means of a fuel recharge and pre determined control rod patterns. By this way a good axial fuel design one has, when the thermal limits are fulfilled along the cycle, the reactor stays critic and at least the wanted longitude of the cycle is reached; also the margin of in cold turned off is verified. The assemble of fuel created with RENODC it is substituted by a recharge assemble and it is sought to verify that the energy requirements and aspects of safety are completed. The used cycle corresponds to a balance cycle of 18 months that it can be applied to the Laguna Verde Nucleo electric Central. The tests demonstrate the effectiveness of the system to reach satisfactory results in times of CPU of around 4 hours. This way, it could be proven that the design proposed with a lightly superior enrichment to that of the substituted design, fulfills the energy requirements. In later stages of this project this system will be coupled to the other optimization modules that are already had. (Author)
Axial design of nuclear fuel using path relinking
International Nuclear Information System (INIS)
Castillo, A.; Torres, M.; Ortiz, J. J.; Perusquia, R.; Hernandez, J. L.; Montes, J. L.
In the present work the preliminary results were obtained with the zoctli system whose purpose is the axial design of assembly of nuclear fuel under certain considerations. For the mentioned design well-know cells were already used and that they have been proven in diverse cycles of operation in the nuclear power plant of Laguna Verde. The design contemplates fuels assemblies of 10x10 and with 2 water channels. The assembly was distributed in 6 axial zones according to its structure. In order to take to end the optimization is was used the well-known technique like Path relinking and to find the group of previous solutions required by this technique uses the technical Taboo search. In order to work with Path relinking, 5 trajectories was taken in to account from a set of 5 previous solutions generated with theTaboo search, the update of the group of solutions is carried out in dynamic form. In the case of the Taboo search it was used a list of variable size, it was implement an aspiration approach, it was used the vector of frequencies and due to the cost of the evaluation of the objective function, only it was review 5% of the vicinity. For the objective function was considered the limit thermal, the axial profile of power, the effective multiplication factor and the margin of having turned off in cold. In order to prove the design system, it was used a balance cycle with a value of reference of 0.9928 for the effective multiplication factor that is equivalent to a produced energy of 10896 MWd/TU at the end of operation to full power. The designed assemblies were placed both in one of lots different from fresh assemblies on which it counts the referred cycle. At the end one a comparison with the results obtained with other techniques and under similar conditions is made. The results obtained until the moment show an appropriate performance of the system. It is possible to indicate that a small inconvenient is the amount of consumed resources of calculation during
Three-dimensional S-wave tomography under Axial Seamount
Baillard, C.; Wilcock, W. S. D.; Arnulf, A. F.; Tolstoy, M.; Waldhauser, F.
Axial Seamount is a submarine volcano located at the intersection of the Juande Fuca Ridge and the Cobb-Eickelberg hotspot 500 km off the coast of thenorthwestern United States. The seamount, which rises 1 km above the seafloor, ischaracterized by a shallow caldera that is elongated in the N-S direction, measure 8km by 3 km and sits on top of a 14 km by 3 km magma reservoir. Two eruptive eventsin 1998 and 2011 motivated the deployment in 2014 of a real time cabled observatorywithin the Axial caldera, as part of the Ocean Observatories Initiative (OOI).Theobservatory includes a network of seven seismometers that span the southern half ofthe caldera. Five months after the observatory came on-line in November 2014, thevolcano erupted on April 24, 2015. Well over 100,000 events were located in thevicinity of the caldera, delineating an outward dipping ring fault that extends fromnear the surface to the magma body at 2 km depth and which accommodatesinflation and deflation of the volcano.The initial earthquake locations have beenobtained with a one-dimensional velocity model but the travel time residuals suggeststrong heterogeneities. A three-dimensional P-wave velocity model, obtained bycombining multichannel and ocean bottom seismometer refraction data, is being usedto refine locations but the three-dimensional S-wave structure is presently unknown.In most mid-ocean ridge settings, the distribution of earthquakes is not conducive forjoint inversions for S-wave velocity and hypocentral parameters because there are fewcrossing ray paths but at Axial the presence of a ring fault that is seismically active atall depths on both the east and west side of the caldera, provides a reasonablegeometry for such efforts. We will present the results of joint inversions that assumethe existing three-dimensional P wave velocity model and solve for VP/VS structure andhypocentral parameters using LOTOS, an algorithm that solves the forward problemusing ray bending.The resulting model
Axial to transverse energy mixing dynamics in octupole-based magnetostatic antihydrogen traps
Zhong, M.; Fajans, J.; Zukor, A. F.
The nature of the trajectories of antihydrogen atoms confined in an octupole minimum-B trap is of great importance for upcoming spectroscopy, cooling, and gravity experiments. Of particular interest is the mixing time between the axial and transverse energies for the antiatoms. Here, using computer simulations, we establish that almost all trajectories are chaotic, and then quantify the characteristic mixing time between the axial and transverse energies. We find that there are two classes of trajectories: for trajectories whose axial energy is higher than about 20% of the total energy, the axial energy substantially mixes within about 10 s, whereas for trajectories whose axial energy is lower than about 10% of the total energy, the axial energy remains nearly constant for 1000 s or longer.
Axial power deviation control strategy and computer simulation for Daya Bay Nuclear Power Station
International Nuclear Information System (INIS)
Liao Yehong; Zhou Xiaoling, Xiao Min
Daya Bay Nuclear Power Station has very tight operation diagram especially at its right side. Therefore the successful control of axial power deviation for PWR is crucial to nuclear safety. After analyzing various core characters' effect on axial power distribution, several axial power deviation control strategies has been proposed to comply with different power varying operation scenario. Application and computer simulation of the strategies has shown that our prediction of axial power deviation evolution are comparable to the measurement values, and that our control strategies are effective. Engineering experience shows that the application of our methodology can predict accurately the transient of axial power deviation, and therefore has become a useful tool for reactor operation and safety control. This paper presents the axial power control characteristics, reactor operation strategy research, computer simulation, and comparison to measurement results in Daya Bay Nuclear Power Station. (author)
Second harmonic generation of off axial vortex beam in the case of walk-off effect
Chen, Shunyi; Ding, Panfeng; Pu, Jixiong
Process of off axial vortex beam propagating in negative uniaxial crystal is investigated in this work. Firstly, we get the formulae of the normalized electric field and calculate the location of vortices for second harmonic beam in two type of phase matching. Then, numerical analysis verifies that the intensity distribution and location of vortices of the first order original vortex beam depend on the walk-off angle and off axial magnitude. It is shown that, in type I phase matching, the distribution of vortices is symmetrical about the horizontal axis, the separation distance increases as the off axial magnitude increases or the off axial magnitude deceases. However, in type II phase matching, the vortices are symmetrical along with some vertical axis, and increase of the walk-off angle or off axial magnitude leads to larger separation distance. Finally, the case of high order original off axial vortex beam is also investigated.
Study of Fuel Rods Axial Enrichment Distribution Effect on the Neutronic Parameters of the Reactor Core
International Nuclear Information System (INIS)
Pazirandeh, A.; Nasiri, S. H.
Optimization of the fuel burn up is an important issue in nuclear reactor fuel management and technology. Radial enrichment distribution in the reactor core is a conventional method and axial enrichment is constant along the fuel rod. In this article, the effects of axial enrichment distribution variation on neutronic parameters of PWR core are studied. The axial length of the core is divided into ten sections, considering axial enrichment variation and leaving the existing radial enrichment distribution intact. This study shows that the radial and axial power peaking factors are decreased as compared with the typical conventional core. In addition, the first core lifetime lasts 30 days longer than normal PWR core. Moreover, at the same time boric acid density is 0.2 g/kg at the beginning of the cycle. The flux shape is also flat at the beginning of the cycle for the proposed configuration of the axially enrichment distribution.
Launch Lock Assemblies Including Axial Gap Amplification Devices and Spacecraft Isolation Systems Including the Same
Barber, Tim Daniel (Inventor); Hindle, Timothy (Inventor); Young, Ken (Inventor); Davis, Torey (Inventor)
Embodiments of a launch lock assembly are provided, as are embodiments of a spacecraft isolation system including one or more launch lock assemblies. In one embodiment, the launch lock assembly includes first and second mount pieces, a releasable clamp device, and an axial gap amplification device. The releasable clamp device normally maintains the first and second mount pieces in clamped engagement; and, when actuated, releases the first and second mount pieces from clamped engagement to allow relative axial motion there between. The axial gap amplification device normally residing in a blocking position wherein the gap amplification device obstructs relative axial motion between the first and second mount pieces. The axial gap amplification device moves into a non-blocking position when the first and second mount pieces are released from clamped engagement to increase the range of axial motion between the first and second mount pieces.
Simulation Analysis and Experiment of Variable-Displacement Asymmetric Axial Piston Pump
Directory of Open Access Journals (Sweden)
Youshan Gao
Full Text Available The variable displacement pump control system has greater energy-saving advantages and application prospects than the valve control system. However, the variable displacement pump control of differential cylinder is not concurrent with the existing technologies. The asymmetric pump-controlled cylinder is, therefore, used to balance the unequal volume flow through a single rod cylinder in closed-circuit system. This is considered to be an effective method. Nevertheless, the asymmetric axial piston pump (AAPP is a constant displacement pump. In this study, variable-displacement asymmetric axial piston pump (VAPP is investigated according to the same principle used in investigating AAPP. This study, therefore, aims at investigating the characteristics of VAPP. The variable-displacement output of VAPP is implemented by controlling the swash plate angle with angle feedback control circuit, which is composed of a servo proportional valve and an angular displacement sensor. The angular displacement sensor is connected to the swash plate. The simulation model of VAPP, which is set up through the ITI-SimulationX simulation platform, is used to predict VAPP's characteristics. The purpose of implementing the experiment is to verify the theoretical results. Both the simulation and the experiment results demonstrated that the swash plate angle is controlled by a variable mechanism; when the swash plate angle increases, the flow of Port B and Port T increases while the response speed of Port B and Port T also accelerates. When the swash plate angle is constant, the flow of Port B and Port T increases along with the increase of pump speed, although the pressure-response speed of Port B is faster than that of Port T. Consequently, the flow pulsation of Port B and Port T tends to decrease gradually along with the increase of pump speed. When the pressure loaded on Port B equals to that of Port T, the flow ripple cycle of Port B is longer than that of Port T
Design, Test, and Evaluation of a Transonic Axial Compressor Rotor with Splitter Blades
INTRODUCTION A. MOTIVATION Over the course of turbomachinery history splitter vanes have been used extensively in centrifugal compressors . Axial...TEST, AND EVALUATION OF A TRANSONIC AXIAL COMPRESSOR ROTOR WITH SPLITTER BLADES by Scott Drayton September 2013 Dissertation Co...AXIAL COMPRESSOR ROTOR WITH SPLITTER BLADES 5. FUNDING NUMBERS 6. AUTHOR(S) Scott Drayton 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES
Metamorphosis of helical magnetorotational instability in the presence axial electric current
Priede, Jānis
This paper presents numerical linear stability analysis of a cylindrical Taylor-Couette flow of liquid metal carrying axial electric current in a generally helical external magnetic field. Axially symmetric disturbances are considered in the inductionless approximation corresponding to zero magnetic Prandtl number. Axial symmetry allows us to reveal an entirely new electromagnetic instability. First, we show that the electric current passing through the liquid can extend the range of helical ...
Precautions against axial fan stall in reactor building to Tianwan NPP
International Nuclear Information System (INIS)
Liu Chunlong; Pei Junmin
The paper introduces the mechanism and harm of rotating stall of axial fans, analyzes the necessity for prevention against axial fan stall in reactor building of Tianwan NPP, introduces the precautions, and then makes an assessment on anti-stall effect of flow separators. It can provide reference for model-selection or reconstruction of similar fans in power stations, and for operation and maintenance of axial fans. (authors)
Atlanto-axial Subluxation in rheumatoid arthritis: description of a case
International Nuclear Information System (INIS)
Medina, Yimy F; Martinez V, Jose B; Restrepo, Jose Felix; Rondon H, Federico; Iglesias G, Antonio
The damage of the spine by rheumatoid arthritis is multiple and a variety of affectations have been described at cervical level, being the anterior atlanto-axial subluxation and vertical subluxation the more common. However the posterior atlanto-axial subluxation has been rarely described. In this paper, we describe the case of a patient with posterior atlanto-axial subluxaction in addition to its infrequent manifestation of alteration of the lower cranial nerves as a manifestation of myelopathy
Endoscopic Transoral Resection of an Axial Chordoma: A Case Report
Directory of Open Access Journals (Sweden)
Taran S
Full Text Available Upper cervical chordoma (UCC is rare condition and poses unique challenges to surgeons. Even though transoral approach is commonly employed, a minimally invasive technique has not been established. We report a 44-year old Malay lady who presented with a 1 month history of insidious onset of progressive neck pain without neurological symptoms. She was diagnosed to have an axial (C2 chordoma. Intralesional resection of the tumour was performed transorally using the Destandau endoscopic system (Storz, Germany. Satisfactory intralesional excision of the tumour was achieved. She had a posterior fixation of C1-C4 prior to that. Her symptoms improved postoperatively and there were no complications noted. She underwent adjuvant radiotherapy to minimize local recurrence. Endoscopic excision of UCC via the transoral approach is a safe option as it provides an excellent magnified view and ease of resection while minimizing the operative morbidity.
On the mechanism of zircaloy cladding axial splits
International Nuclear Information System (INIS)
Grigoriev, V.; Josefsson, B.
The macroscopically brittle axial splitting is treated as a process entirely accomplished by a plastic mechanism operating on a microscopic scale and is discussed in terms of the degree of plasticity and localisation of plasticity. The suggested mechanism involves hydrogen assisted localised shear (HALS) as a main factor of material deterioration. The reason and the driving force for the HALS is an in-plane shear (as for mode II loading) existing at the tip of a crack loaded in mode I (Opening). The HALS mechanism does not require brittle fracture of the hydrides and is only operable under certain combination of material strength, applied stresses, and temperature, needed for the local yielding at the crack tip. If the combination of those parameters results in the bulk yielding, the in-plane shear component is diminished and the delayed cracking is suppressed. (orig.)
Stress Analysis of Fuel Rod under Axial Coolant Flow
Energy Technology Data Exchange (ETDEWEB)
Jin, Hai Lan; Lee, Young Shin; Lee, Hyun Seung [Chungnam National University, Daejeon (Korea, Republic of); Park, Num Kyu; Jeon, Kyung Rok [Kerea Nuclear Fuel., Daejeon (Korea, Republic of)
A pressurized water reactor(PWR) fuel assembly, is a typical bundle structure, which uses light water as a coolant in most commercial nuclear power plants. Fuel rods that have a very slender and long clad are supported by fuel assembly which consists of several spacer grids. A coolant is a fluid which flows through device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. But at the same time, the coolant flow will bring out the fluid induced vibration(FIV) of fuel rods and even damaged the fuel rod. This study has been conducted to investigate the flow characteristics and nuclear reactor fuel rod stress under effect of coolant. Fluid structure interaction(FSI) analysis on nuclear reactor fuel rod was performed. Fluid analysis of the coolant which flow along the axial direction and structural analysis under effect of flow velocity were carried out under different output flow velocity conditions
Active surge control for variable speed axial compressors.
Lin, Shu; Yang, Chunjie; Wu, Ping; Song, Zhihuan
This paper discusses active surge control in variable speed axial compressors. A compression system equipped with a variable area throttle is investigated. Based on a given compressor model, a fuzzy logic controller is designed for surge control and a proportional speed controller is used for speed control. The fuzzy controller uses measurements of the change of pressure rise as well as the change of mass flow to determine the throttle opening. The presented approach does not require the knowledge of system equilibrium or the surge line. Numerical simulations show promising results. The proposed fuzzy logic controller performs better than a backstepping controller and is capable to suppress surge at different operating points. Copyright © 2014 ISA. Published by Elsevier Ltd. All rights reserved.
Computerized axial tomography and diagnosis of multiple sclerosis
Directory of Open Access Journals (Sweden)
Paulo R.M. Bittencourt
Full Text Available Computed axial tomography (C.T. findings are illustrated in 3 patients who presented with C.T. changes suggesting respectively chronic M.S., acute M.S., and an appearance simulating a malignant tumour. Review of the literature shows that the chronic form with cerebral atrophy and low density lesions in the hemispheres is common in patients with a long history and is unlikely to cause diagnostic difficulty. The acute presentation is less common and could be confused with a variety of causes of multiple low density enhancing lesions. The C.T. diagnosis of M.S. is more difficult in rare cases in which plaques cause mass effect and show ring enhancement; all 3 such cases in the literature were subjected to cerebral biopsy.
Structures of water molecular nanotube induced by axial tensile strains
Energy Technology Data Exchange (ETDEWEB)
Li, H. [Key Laboratory of Liquid Structures and Heredity of Materials, Ministry of Education, School of Materials Science and Engineering, Shandong University (China)], E-mail: email@example.com; Zhang, X.Q. [Physics Department, Ocean University of China, Qingdao (China); Liew, K.M. [Department of Building and Constructions, City University of Hong Kong, Kowloon (Hong Kong); Liu, X.F. [Key Laboratory of Liquid Structures and Heredity of Materials, Ministry of Education, School of Materials Science and Engineering, Shandong University (China)
Five well-ordered nano-ice structures embedded in carbon nanotubes are obtained in this study. These five nano-ice phases all exhibit single walled tubular morphologies, including the pentagon, hexagon ice nanotubes whose structures are quite different from bulk ice. Our simulation results indicate that water molecules tend to rearrange into surface ring structures to reduce the number of free OH groups. The structural behavior of these ice nanotubes inside CNTs subject to axial stress is also investigated. The ice nanotubes tend to be drawn to ice nanorings or ice nanospring during the mechanical stretching. The distribution function exhibits typical order-to-disorder transition of the water network confined in carbon nanotube during the stretching. By analysis, we suggest that it is unlikely that additional water molecules will enter the tubes because of the increased volume available if the tubes are stretched at contact with a water reservoir.
Axial shape index calculation for the 3-level excore detector
Energy Technology Data Exchange (ETDEWEB)
Kim, Han Gon; Kim, Yong Hee; Kim, Byung Sop; Lee, Sang Hee; Cho, Sung Jae [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
A new method based on the alternating conditional expectation (ACE) algorithm is developed to calculate axial shape index (ASI) for the 3-level excore detector. The ACE algorithm, a type of nonparametric regression algorithms, yields an optimal relationship between a dependent variable and multiple independent variables. In this study, the simple correlation between ASI and excore detector signals is developed using the Younggwang nuclear power plant unit 3 (YGN-3) data without any preprocessing on the relationships between independent variables and dependent variable. The numerical results show that simple correlations exist between the three excore signals and ASI of the core. The accuracy of the new method is much better than those of the current CPC and COLSS algorithms. 5 refs., 2 figs., 2 tabs. (Author)
A review of X-ray computed axial tomography
International Nuclear Information System (INIS)
Schmidt, M.
A review of Computed axial tomography (CAT) scanning literature outlining the theoretical and practical aspects of this technique with application in both medical diagnosis and industrial non-destructive inspection (NDI) is presented. Practical aspects of CAT scanning discussed include : radiation sources, currently available spatial and contrast resolution limits and the evolution of the computerized tomography (CT) system. It was found that monochromatic gamma rays are preferred to X-rays, especially for very high density materials, and that in medical CAT scanning, the special resolution is only, 0.5 mm while spatial resolutions of less than 50μm have been achieved in NDI. An increased number of scientific and industrial applications are anticipated (e.g. for studying sintering reactions), as the capital cost of CAT scanning decreased. 13 refs., 9 figs., 2 tabs
Development of throughflow calculation code for axial flow compressors
International Nuclear Information System (INIS)
Kim, Ji Hwan; Kim, Hyeun Min; No, Hee Cheon
The power conversion systems of the current HTGRs are based on closed Brayton cycle and major concern is thermodynamic performance of the axial flow helium gas turbines. Particularly, the helium compressor has some unique design challenges compared to the air-breathing compressor such as high hub-to-tip ratios throughout the machine and a large number of stages due to the physical property of the helium and thermodynamic cycle. Therefore, it is necessary to develop a design and analysis code for helium compressor that can estimate the design point and off-design performance accurately. KAIST nuclear system laboratory has developed a compressor design and analysis code by means of throughflow calculation and several loss models. This paper presents the outline of the development of a throughflow calculation code and its verification results
Predicting the Coupling Properties of Axially-Textured Materials
Directory of Open Access Journals (Sweden)
María E. Fuentes-Montero
Full Text Available A description of methods and computer programs for the prediction of "coupling properties" in axially-textured polycrystals is presented. Starting data are the single-crystal properties, texture and stereography. The validity and proper protocols for applying the Voigt, Reuss and Hill approximations to estimate coupling properties effective values is analyzed. Working algorithms for predicting mentioned averages are given. Bunge's symmetrized spherical harmonics expansion of orientation distribution functions, inverse pole figures and (single and polycrystals physical properties is applied in all stages of the proposed methodology. The established mathematical route has been systematized in a working computer program. The discussion of piezoelectricity in a representative textured ferro-piezoelectric ceramic illustrates the application of the proposed methodology. Polycrystal coupling properties, predicted by the suggested route, are fairly close to experimentally measured ones.
Predicting the Coupling Properties of Axially-Textured Materials
Fuentes-Cobas, Luis E.; Muñoz-Romero, Alejandro; Montero-Cabrera, María E.; Fuentes-Montero, Luis; Fuentes-Montero, María E.
A description of methods and computer programs for the prediction of "coupling properties" in axially-textured polycrystals is presented. Starting data are the single-crystal properties, texture and stereography. The validity and proper protocols for applying the Voigt, Reuss and Hill approximations to estimate coupling properties effective values is analyzed. Working algorithms for predicting mentioned averages are given. Bunge's symmetrized spherical harmonics expansion of orientation distribution functions, inverse pole figures and (single and polycrystals) physical properties is applied in all stages of the proposed methodology. The established mathematical route has been systematized in a working computer program. The discussion of piezoelectricity in a representative textured ferro-piezoelectric ceramic illustrates the application of the proposed methodology. Polycrystal coupling properties, predicted by the suggested route, are fairly close to experimentally measured ones. PMID:28788370
Static Tension Tests on Axially Loaded Pile Segments in Sand
DEFF Research Database (Denmark)
Thomassen, Kristina; Andersen, Lars Vabbersgaard; Ibsen, Lars Bo
This paper provides laboratory test results of static axially loaded piles in sand. With a newly developed test setup, the pile-soil interface friction was investigated by using an open-ended steel pile segment with a diameter of 0.5 m. Use of a pile length of 1 m enabled the pile-soil interface...... friction to be analyzed at a given soil horizon while increasing the vertical effective stress in the sand. Test results obtained by this approach can be analyzed as single t-z curves and compared to predictions of unit shaft friction from current design methods for offshore foundations. The test results...... showed best agreement with the traditional design method given in the American Petroleum Institute (API) design code. When t-z curves obtained from the test results were compared to t-z curve formulations found in the literature, the Zhang formulation gave good predictions of the initial and post...
Axial shape index calculation for the 3-level excore detector
Energy Technology Data Exchange (ETDEWEB)
Kim, Han Gon; Kim, Yong Hee; Kim, Byung Sop; Lee, Sang Hee; Cho, Sung Jae [Korea Electric Power Research Institute, Taejon (Korea, Republic of)
A new method based on the alternating conditional expectation (ACE) algorithm is developed to calculate axial shape index (ASI) for the 3-level excore detector. The ACE algorithm, a type of nonparametric regression algorithms, yields an optimal relationship between a dependent variable and multiple independent variables. In this study, the simple correlation between ASI and excore detector signals is developed using the Younggwang nuclear power plant unit 3 (YGN-3) data without any preprocessing on the relationships between independent variables and dependent variable. The numerical results show that simple correlations exist between the three excore signals and ASI of the core. The accuracy of the new method is much better than those of the current CPC and COLSS algorithms. 5 refs., 2 figs., 2 tabs. (Author)
On the axial anomalies in external tensor fields
International Nuclear Information System (INIS)
Khudaverdyan, O.M.; Mkrtchyan, R.L.; Zurabyan, L.A.
Computation of the axial anomaly for Dirac fermions in external tensor fields is studied. The sequence of the supersymmetric one-dimensional models is presented. Their supercharges are equal, after quantization, to Dirac operators in external tensor fields, and the density of Witten's partition function gives the anomaly. It is shown that action in the corresponding path integral differs from the classical one. Gaussian approximation gives the anomaly only in the case of third-rank tensor with zero exterior derivative and in that case anomaly is calculated in all dimensions. The interpretation of that field as the torsion of gravitational field and also connection with the results of Witten and Alvarez-Gaume and Atiyah-Singer index theorem are discussed
Stress Analysis of Fuel Rod under Axial Coolant Flow
International Nuclear Information System (INIS)
Jin, Hai Lan; Lee, Young Shin; Lee, Hyun Seung; Park, Num Kyu; Jeon, Kyung Rok
A pressurized water reactor(PWR) fuel assembly, is a typical bundle structure, which uses light water as a coolant in most commercial nuclear power plants. Fuel rods that have a very slender and long clad are supported by fuel assembly which consists of several spacer grids. A coolant is a fluid which flows through device to prevent its overheating, transferring the heat produced by the device to other devices that use or dissipate it. But at the same time, the coolant flow will bring out the fluid induced vibration(FIV) of fuel rods and even damaged the fuel rod. This study has been conducted to investigate the flow characteristics and nuclear reactor fuel rod stress under effect of coolant. Fluid structure interaction(FSI) analysis on nuclear reactor fuel rod was performed. Fluid analysis of the coolant which flow along the axial direction and structural analysis under effect of flow velocity were carried out under different output flow velocity conditions
Study of axial protections of unloading machines of graphite piles
International Nuclear Information System (INIS)
Duco, Jacques; Pepin, Pierre; Cabaret, Guy; Dubor, Monique
As previous studies resulted in the development of a simple calculation formula based on experimental results for the calculation of neutron protection thicknesses for loading machines, this study aimed at determining axial protections of these machines which represent a specific problem: scattering of delayed neutrons in the machine inner cavity may result in an important neutron leakage through the upper part, at the level of the winch enclosure. In an experimental part, this study comprises the measurement of the neutron dose in a 2.60 m long and 54 cm diameter cylindrical cavity, and in the thickness of the surrounding concrete protection. In the second part, the authors present a calculation method which uses the Zeus and Mercure codes to interpret the results [fr
Treatment of the axial friction forces in the transuranus code
International Nuclear Information System (INIS)
Lassmann, K.
The problems of calculating axial friction forces are discussed. It is found that for the majority of failure analyses or safety related analyses under normal, off-normal and accident conditions a detailed model which takes all different modes of interaction between fuel and cladding into account is indispensable. The URFRIC model described in this paper is such a model. It is formulated in an extremely efficient numerical algorithm which saves computational costs. The URFRIC model has been applied successfully for 2 years in the TRANSURANUS code, and may in principle also be used in other quasi two-dimensional fuel performance codes. Results of this model are compared with results from a simple slip and a simple noslip model. Recommendations are given for the use of each of these models
Simple LMFBR axial-flow friction-factor correlation
International Nuclear Information System (INIS)
Chan, Y.N.; Todreas, N.E.
Complicated LMFBR axial lead-length averaged friction factor correlations are reduced to an easy, ready-to-use function of bundle Reyonlds number for wire-wrapped bundles. The function together with the power curves to calculate the associated constants are incorporated in a computer pre-processor, EZFRIC. The constants required for the calculation of the subchannels and bundle friction factors are derived and correlated into power curves of geometrical parameters. A computer program, FRIC, which can alternatively be used to accurately calculate these constants is also included. The accuracte values of the constants and the corresponding values predicted by the power curves and percentage error of prediction are tabulated for a wide variety of geometries of interest
Phenomenological model for coupled multi-axial piezoelectricity
Wei, Yuchen; Pellegrino, Sergio
A quantitative calibration of an existing phenomenological model for polycrystalline ferroelectric ceramics is presented. The model relies on remnant strain and polarization as independent variables. Innovative experimental and numerical model identification procedures are developed for the characterization of the coupled electro-mechanical, multi-axial nonlinear constitutive law. Experiments were conducted on thin PZT-5A4E plates subjected to cross-thickness electric field. Unimorph structures with different thickness ratios between PZT-5A4E plate and substrate were tested, to subject the piezo plates to coupled electro-mechanical fields. Material state histories in electric field-strain-polarization space and stress-strain-polarization space were recorded. An optimization procedure is employed for the determination of the model parameters, and the calibrated constitutive law predicts both the uncoupled and coupled experimental observations accurately.
Computer aided hydraulic design of axial flow pump impeller
International Nuclear Information System (INIS)
Sreedhar, B.K.; Rao, A.S.L.K.; Kumaraswamy, S.
Pumps are the heart of any power plant and hence their design requires great attention. Computers with their potential for rapid computation can be successfully employed in the design and manufacture of these machines. The paper discusses a program developed for the hydraulic design of axial flow pump impeller. The program, written in FORTRAN 77, is interactive and performs the functions of design calculation, drafting and generation of numerical data for blade manufacture. The drafting function, which makes use of the software ACAD, is carried out automatically by means of suitable interface programs. In addition data for blade manufacture is also generated in either the x-y-z or r-θ-z system. (author). 4 refs., 3 figs
Hamilton's equations for a fluid membrane: axial symmetry
International Nuclear Information System (INIS)
Capovilla, R; Guven, J; Rojas, E
Consider a homogeneous fluid membrane, or vesicle, described by the Helfrich-Canham energy, quadratic in the mean curvature. When the membrane is axially symmetric, this energy can be viewed as an 'action' describing the motion of a particle; the contours of equilibrium geometries are identified with particle trajectories. A novel Hamiltonian formulation of the problem is presented which exhibits the following two features: (i) the second derivatives appearing in the action through the mean curvature are accommodated in a natural phase space and (ii) the intrinsic freedom associated with the choice of evolution parameter along the contour is preserved. As a result, the phase space involves momenta conjugate not only to the particle position but also to its velocity, and there are constraints on the phase space variables. This formulation provides the groundwork for a field theoretical generalization to arbitrary configurations, with the particle replaced by a loop in space
Gearbox Instrumentation for the Investigation of Bearing Axial Cracking
Energy Technology Data Exchange (ETDEWEB)
Keller, Jonathan A [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lambert, Scott R [National Renewable Energy Laboratory (NREL), Golden, CO (United States)
Failures in gearbox bearings have been the primary source of reliability issues for wind turbine drivetrains, leading to costly downtime and unplanned maintenance. The most common failure mode is attributed to so-called axial cracks or white-etching cracks, which primarily affect the intermediate and high-speed-stage bearings. The high-speed-shaft and bearing loads and sliding will be measured with a specially instrumented gearbox installed in a 1.5-megawatt turbine at the National Wind Technology Center in an upcoming test campaign. Additional instrumentation will also measure the tribological environment of these bearings, including bearing temperatures, lubricant temperature and water content, air temperature and humidity, and stray electrical current across the bearings. This paper fully describes the instrumentation package and summarizes initial results.
Control of hole localization in magnetic semiconductors by axial strain
Raebiger, Hannes; Bae, Soungmin; Echeverría-Arrondo, Carlos; Ayuela, Andrés
Mn and Fe-doped GaN are widely studied prototype systems for hole-mediated magnetic semiconductors. The nature of the hole states around the Mn and Fe impurities, however, remains under debate. Our self-interaction corrected density-functional calculations show that the charge neutral Mn 0 and positively charged Fe+ impurities have symmetry-broken d5+h ground states, in which the hole is trapped by one of the surrounding N atoms in a small polaron state. We further show that both systems also have a variety of other d5+h configurations, including symmetric, delocalized states, which may be stabilized by axial strain. This finding opens a pathway to promote long-range hole-mediated magnetic interactions by strain engineering and clarifies why highly strained thin-films samples often exhibit anomalous magnetic properties.
Computerized axial tomography in the detection of brain damage
International Nuclear Information System (INIS)
Cala, L.A.; Mastaglia, F.L.
The cranial computerized axial tomography (CAT) findings in groups of patients with epilepsy, migraine, hypertension, and other general medical disorders have been reviewed to assess the frequency and patterns of focal and diffuse brain damage. In addition to demonstrating focal lesions in a proportion of patients with seizures and in patients presenting with a stroke, the CAT scan showed a premature degree of cerebral atrophy in an appreciable proportion of patients with long-standing epilepsy, hypertension and diabetes, and in some patients with migraine, valvular and ischaemic heart disease, chronic obstructive airways disease, and chronic renal failure. The value of CAT as a means of screening for brain damage in groups of individuals at risk is discussed
A cryogenic axial-centrifugal compressor for superfluid helium refrigeration
Decker, L; Schustr, P; Vins, M; Brunovsky, I; Lebrun, P; Tavian, L
CERN's new project, the Large Hadron Collider (LHC), will use superfluid helium as coolant for its high-field superconducting magnets and therefore require large capacity refrigeration at 1.8 K. This may only be achieved by subatmospheric compression of gaseous helium at cryogenic temperature. To stimulate development of this technology, CERN has procured from industry prototype Cold Compressor Units (CCU). This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating under low-pressure helium at ambient temperature. The machine has been commissioned and is now in operation. After describing basic constructional features of the compressor, we report on measured performance.
Operational Experience with a Cryogenic Axial-Centrifugal Compressor
Decker, L; Löhlein, K; Purtschert, W; Ziegler, B L; Lebrun, P; Tavian, L; Brunovsky, I; Tucek, L
The Large Hadron Collider (LHC), presently under construction at CERN, requires large refrigeration capacity at 1.8 K. Compression of gaseous helium at cryogenic temperatures is therefore inevitable. Together with subcontractors, Linde Kryotechnik has developed a prototype machine. This unit is based on a cryogenic axial-centrifugal compressor, running on ceramic ball bearings and driven by a variable-frequency electrical motor operating at ambient temperature. Integrated in a test facility for superconducting magnets the machine has been commissioned without major problems and successfully gone through the acceptance test in autumn 1995. Subsequent steps were initiated to improve efficiency of this prototype. This paper describes operating experience gained so far and reports on measured performance prior to and after constructional modifications.
Axial turbomachine modelling with a 1D axisymmetric approach
International Nuclear Information System (INIS)
Tauveron, Nicolas; Saez, Manuel; Ferrand, Pascal; Leboeuf, Francis
This work concerns the design and safety analysis of direct cycle gas cooled reactor. The estimation of compressor and turbine performances in transient operations is of high importance for the designer. The first goal of this study is to provide a description of compressor behaviour in unstable conditions with a better understanding than the models based on performance maps ('traditional' 0D approach). A supplementary objective is to provide a coherent description of the turbine behaviour. The turbomachine modelling approach consists in the solution of 1D axisymmetric Navier-Stokes equations on an axial grid inside the turbomachine: mass, axial momentum, circumferential momentum and total-enthalpy balances are written. Blade forces are taken into account by using compressor or turbine blade cascade steady correlations. A particular effort has been developed to generate or test correlations in low mass flow and negative mass flow regimes, based on experimental data. The model is tested on open literature cases of the gas turbine aircraft community. For compressor and turbine, steady situations are fairly described, especially for medium and high mass flow rate. The dynamic behaviour of compressor is also quite well described, even in unstable operation (surge): qualitative tendencies (role of plenum volume and role of throttle) and some quantitative characteristics (frequency) are in a good agreement with experimental data. The application to transient simulations of gas cooled nuclear reactors is concentrated on the hypothetical 10 in. break accident. The results point out the importance of the location of the pipe rupture in a hypothetical break event. In some detailed cases, compressor surge and back flow through the circuit can occur. In order to be used in a design phase, a simplified model of surge has also been developed. This simplified model is applied to the gas fast reactor (GFR) and compared quite favourably with 1D axisymmetric simulation results
A Novel Geometry for Shear Test Using Axial Tensile Setup
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Sibo Yuan
Full Text Available This paper studies a novel geometry for the in-plane shear test performed with an axial electromechanical testing machine. In order to investigate the influence of the triaxiality rate on the mechanical behavior, different tests will be performed on the studied material: simple tensile tests, large tensile tests and shear tests. For the whole campaign, a common equipment should be employed to minimize the impact of the testing device. As a consequence, for the shear tests, the geometry of the specimen must be carefully designed in order to adapt the force value and make it comparable to the one obtained for the tensile tests. Like most of the existing shear-included tensile test specimens, the axial loading is converted to shear loading at a particular region through the effect of geometry. A symmetric shape is generally preferred, since it can restrict the in-plane rotation of the shear section, keep shear increasing in a more monotonic path and double the force level thanks to the two shear zones. Due to the specific experimental conditions, such as dimensions of the furnace and the clamping system, the position of the extensometer or the restriction of sheet thickness (related to the further studies of size effect at mesoscale and hot temperature, several geometries were brought up and evaluated in an iterative procedure via finite element simulations. Both the numerical and experimental results reveal that the final geometry ensures some advantages. For instance, a relatively low triaxiality in the shear zone, limited in-plane rotation and no necking are observed. Moreover, it also prevents any out-of-plane displacement of the specimen which seems to be highly sensitive to the geometry, and presents a very limited influence of the material and the thickness.
Axial magnetic field injection in magnetized liner inertial fusion
Gourdain, P.-A.; Adams, M. B.; Davies, J. R.; Seyler, C. E.
MagLIF is a fusion concept using a Z-pinch implosion to reach thermonuclear fusion. In current experiments, the implosion is driven by the Z-machine using 19 MA of electrical current with a rise time of 100 ns. MagLIF requires an initial axial magnetic field of 30 T to reduce heat losses to the liner wall during compression and to confine alpha particles during fusion burn. This field is generated well before the current ramp starts and needs to penetrate the transmission lines of the pulsed-power generator, as well as the liner itself. Consequently, the axial field rise time must exceed hundreds of microseconds. Any coil capable of being submitted to such a field for that length of time is inevitably bulky. The space required to fit the coil near the liner, increases the inductance of the load. In turn, the total current delivered to the load decreases since the voltage is limited by driver design. Yet, the large amount of current provided by the Z-machine can be used to produce the required 30 T field by tilting the return current posts surrounding the liner, eliminating the need for a separate coil. However, the problem now is the field penetration time, across the liner wall. This paper discusses why skin effect arguments do not hold in the presence of resistivity gradients. Numerical simulations show that fields larger than 30 T can diffuse across the liner wall in less than 60 ns, demonstrating that external coils can be replaced by return current posts with optimal helicity.
Axial ion-electron emission microscopy of IC radiation hardness
Doyle, B. L.; Vizkelethy, G.; Walsh, D. S.; Swenson, D.
A new system for performing radiation effects microscopy (REM) has been developed at Sandia National Laboratory in Albuquerque. This system combines two entirely new concepts in accelerator physics and nuclear microscopy. A radio frequency quadrupole (RFQ) linac is used to boost the energy of ions accelerated by a conventional Tandem Van de Graaff-Pelletron to velocities of 1.9 MeV/amu. The electronic stopping power for heavy ions is near a maximum at this velocity, and their range is ˜20 μm in Si. These ions therefore represent the most ionizing form of radiation in nature, and are nearly ideal for performing single event effects testing of integrated circuits. Unfortunately, the energy definition of the RFQ-boosted ions is rather poor (˜ a few %), which makes problematic the focussing of such ions to the submicron spots required for REM. To circumvent this problem, we have invented ion electron emission microscopy (IEEM). One can perform REM with the IEEM system without focussing or scanning the ion beam. This is because the position on the sample where each ion strikes is determined by projecting ion-induced secondary electrons at high magnification onto a single electron position sensitive detector. This position signal is then correlated with each REM event. The IEEM system is now mounted along the beam line in an axial geometry so that the ions pass right through the electron detector (which is annular), and all of the electrostatic lenses used for projection. The beam then strikes the sample at normal incidence which results in maximum ion penetration and removes a parallax problem experienced in an earlier system. Details of both the RFQ-booster and the new axial IEEM system are given together with some of the initial results of performing REM on Sandia-manufactured radiation hardened integrated circuits.
Rotation of dust plasma crystals in an axial magnetic field
International Nuclear Information System (INIS)
Cheung, F.; Prior, N.; Mitchell, L.
Full text: Micron-sized melamine formaldehyde particles were introduced into argon plasma. As a result, the particles were negatively charged due to collision with the electrons within the plasma. With the right conditions, these particles formed a stable macroscopic crystal lattice, known as dust plasma crystal. In our experiment we conduct at Flinders University, we apply an external axial magnetic field to various configurations of dust plasma crystal. These configurations include small crystal lattices consisting of one to several particles, and large crystal lattices with many hundreds of particles. The magnetic field strength ranged from 0-32G and was uniform over the extent of the crystal. The crystals were observed to be rotating collectively in the left-handed direction under the influence of the axial magnetic field. In the case of the large crystals, the angular velocity was about 2 complete rotations per minute and was proportional to the applied magnetic field. The angular velocity changes only slightly depending on the plasma conditions. Neither radial variance in the angular velocity nor shear velocity in the vertical direction was observed in the crystal's rotational motion. In the case of the small crystals, we managed to rotate 2-6 particles (whether they are planar, 2 layers or tetrahedral). We discovered that the ease and the uniformity of the rotation of the different crystals increase as its rotational symmetry increases. Also an increase in the magnetic field strength will correspond to an increase in the angular velocity. Crystals in the shape of an annulus were also tested for theoretical reasons. The poster presentation will contain the experimental procedures, a detailed analysis and an explanation for such dust plasma crystal rotational motion
Mind the gap - tip leakage vortex in axial turbines
International Nuclear Information System (INIS)
Dreyer, M; Farhat, M; Decaix, J; Münch-Alligné, C
The tendency of designing large Kaplan turbines with a continuous increase of output power is bringing to the front the cavitation erosion issue. Due to the flow in the gap between the runner and the discharge ring, axial turbine blades may develop the so called tip leakage vortex (TLV) cavitation with negative consequences. Such vortices may interact strongly with the wake of guide vanes leading to their multiple collapses and rebounds. If the vortex trajectory remains close to the blade tip, these collapses may lead to severe erosion. One is still unable today to predict its occurrence and development in axial turbines with acceptable accuracy. Numerical flow simulations as well as the actual scale-up rules from small to large scales are unreliable. The present work addresses this problematic in a simplified case study representing TLV cavitation to better understand its sensitivity to the gap width. A Naca0009 hydrofoil is used as a generic blade in the test section of EPFL cavitation tunnel. A sliding mounting support allowing an adjustable gap between the blade tip and wall was manufactured. The vortex trajectory is visualized with a high speed camera and appropriate lighting. The three dimensional velocity field induced by the TLV is investigated using stereo particle image velocimetry. We have taken into account the vortex wandering in the image processing to obtain accurate measurements of the vortex properties. The measurements were performed in three planes located downstream of the hydrofoil for different values of the flow velocity, the incidence angle and the gap width. The results clearly reveal a strong influence of the gap width on both trajectory and intensity of the tip leakage vortex
Mind the gap - tip leakage vortex in axial turbines
Dreyer, M.; Decaix, J.; Münch-Alligné, C.; Farhat, M.
The tendency of designing large Kaplan turbines with a continuous increase of output power is bringing to the front the cavitation erosion issue. Due to the flow in the gap between the runner and the discharge ring, axial turbine blades may develop the so called tip leakage vortex (TLV) cavitation with negative consequences. Such vortices may interact strongly with the wake of guide vanes leading to their multiple collapses and rebounds. If the vortex trajectory remains close to the blade tip, these collapses may lead to severe erosion. One is still unable today to predict its occurrence and development in axial turbines with acceptable accuracy. Numerical flow simulations as well as the actual scale-up rules from small to large scales are unreliable. The present work addresses this problematic in a simplified case study representing TLV cavitation to better understand its sensitivity to the gap width. A Naca0009 hydrofoil is used as a generic blade in the test section of EPFL cavitation tunnel. A sliding mounting support allowing an adjustable gap between the blade tip and wall was manufactured. The vortex trajectory is visualized with a high speed camera and appropriate lighting. The three dimensional velocity field induced by the TLV is investigated using stereo particle image velocimetry. We have taken into account the vortex wandering in the image processing to obtain accurate measurements of the vortex properties. The measurements were performed in three planes located downstream of the hydrofoil for different values of the flow velocity, the incidence angle and the gap width. The results clearly reveal a strong influence of the gap width on both trajectory and intensity of the tip leakage vortex.
Hysteretic Models Considering Axial-Shear-Flexure Interaction
Ceresa, Paola; Negrisoli, Giorgio
Most of the existing numerical models implemented in finite element (FE) software, at the current state of the art, are not capable to describe, with enough reliability, the interaction between axial, shear and flexural actions under cyclic loading (e.g. seismic actions), neglecting crucial effects for predicting the nature of the collapse of reinforced concrete (RC) structural elements. Just a few existing 3D volume models or fibre beam models can lead to a quite accurate response, but they are still computationally inefficient for typical applications in earthquake engineering and also characterized by very complex formulation. Thus, discrete models with lumped plasticity hinges may be the preferred choice for modelling the hysteretic behaviour due to cyclic loading conditions, in particular with reference to its implementation in a commercial software package. These considerations lead to this research work focused on the development of a model for RC beam-column elements able to consider degradation effects and interaction between the actions under cyclic loading conditions. In order to develop a model for a general 3D discrete hinge element able to take into account the axial-shear-flexural interaction, it is necessary to provide an implementation which involves a corrector-predictor iterative scheme. Furthermore, a reliable constitutive model based on damage plasticity theory is formulated and implemented for its numerical validation. Aim of this research work is to provide the formulation of a numerical model, which will allow implementation within a FE software package for nonlinear cyclic analysis of RC structural members. The developed model accounts for stiffness degradation effect and stiffness recovery for loading reversal.
Gender Differences in Axial Spondyloarthritis: Women Are Not So Lucky.
Rusman, T; van Vollenhoven, R F; van der Horst-Bruinsma, I E
Ankylosing spondylitis (AS) was historically seen as a predominantly male disease. However, more recent data showed a more homogenous sex prevalence. Unfortunately, in many studies in axial spondyloarthritis (axSpA), the number of women included is low and the analyses are often not stratified for gender distribution. The purpose of this review is to aggregate the existing data on gender differences in axSpA in order to increase the awareness that female axSpA patients are still under-recognized. Several studies considering gender differences revealed that female axSpA patients had different disease manifestations due to different immunological, hormonal, and genetic responses. For instance, allelic frequencies of the AHNK-gene and tissue non-specific alkaline phosphatase (TNAP) haplotypes differed between men and women with ankylosing spondylitis (AS). In addition, different levels of tumor necrosis factor (TNF), interleukins IL-6, IL-17, and IL-18, were found between the two sexes. Furthermore, female patients show a higher diagnostic delay compared to males. Several studies indicate a higher frequency of extra-articular manifestations (EAM) in female axSpA patients, such as enthesitis, psoriasis, and inflammatory bowel disease (IBD), whereas acute anterior uveitis is more prevalent in male patients. Male AS patients more frequently show a higher Bath Ankylosing Spondylitis Radiology Index (BASRI) scores and modified Stoke Ankylosing Spondylitis Spine Scores (mSASSS) than females, which indicates that males have higher radiological damage and radiographic progression. However, disease activity (BASDAI) and quality of life (AsQol) scores are significantly higher in women, and more importantly, they have significantly lower response rates to treatment with TNF inhibitors (TNFi) and a significantly lower drug adherence. Despite the fact that men with axial SpA have a worse radiologic prognosis, women have a high disease burden, in part because they have a longer
Axial Skeletal Scintigraphy in Cancer of the Breast
Energy Technology Data Exchange (ETDEWEB)
Galasko, C. S.B. [Royal Postgraduate Medical School and Hammersmith Hospital, London (United Kingdom)
An initial study was made on eight patients shown to have osseous metastases on X-ray. Each patient was examined on two occasions after the injection of {sup 87m}Sr and {sup 18}F. Regions known to contain metastases were examined at regular intervals after each injection. The scintigrams were compared with X-ray skeletal surveys. In all patients the {sup 18}F scintigram gave better results than the {sup 87m}Sr scan. All metastases present on X-ray were detected with the gamma camera and in six patients the scintigram revealed additional lesions. The optimum times for scanning were 1 1/4-3 hours after injection of {sup 18}F and 3-4 1/2 hours after {sup 87m}Sr. Axial skeleton scintigrams using {sup 18}F and a gamma camera are now being done on: (i) patients with apparently 'early' cancer of the breast. (ii) patients who have had a mastectomy and in whom there is a suspicion but no overt evidence of metastases. (iii) patients with advanced cancer of the breast. By means of this method it is hoped: (a) to detect lesions not present on X-ray. (b) to assess progress following hormonal therapy. 'Healing' lesions tend to have a diminished uptake of the isotope, and the varying pattern may prove to be more easy to interpret than conventional X-rays. The technique of axial skeleton scanning with the gamma camera and {sup 18}F, and the results obtained in over 60 patients with cancer of the breast, are reported. (author)
Linear Optical Response of Silicon Nanotubes Under Axial Magnetic Field
Chegel, Raad; Behzad, Somayeh
We investigated the optical properties of silicon nanotubes (SiNTs) in the low energy region, E < 0.5 eV, and middle energy region, 1.8 eV < E < 2 eV. The dependence of optical matrix elements and linear susceptibility on radius and magnetic field, in terms of one-dimensional (1-d) wavevector and subband index, is calculated using the tight-binding approximation. It is found that, on increasing the nanotube diameter, the low-energy peaks show red-shift and their intensities are decreased. Also, we found that in the middle energy region all tubes have two distinct peaks, where the energy position of the second peak is approximately constant and independent of the nanotube diameter. Comparing the band structure of these tubes in different magnetic fields, several differences are clearly seen, such as splitting of degenerate bands, creation of additional band-edge states, and bandgap modification. It is found that applying the magnetic field leads to a phase transition in zigzag silicon hexagonal nanotubes (Si h-NTs), unlike in zigzag silicon gear-like nanotubes (Si g-NTs), which remain semiconducting in any magnetic field. We found that the axial magnetic field has two effects on the linear susceptibility spectrum, namely broadening and splitting. The axial magnetic field leads to the creation of a peak with energy less than 0.2 eV in metallic Si h-NTs, whereas in the absence of a magnetic field such a transition is not allowed.
Evaluation of efficiency of axial profiling in WWER-440 fuel assemblies
International Nuclear Information System (INIS)
Ananjev, Yu. A.; Kurakin, K. Yu.; Artemov, V.G.; Ivanov, A.S.
The present report deals with consideration of fuel enrichment axial profiling in WWER-440 assemblies. The study is performed on improving the effectiveness of fuel utilization using the example of implementing the axial profiling in the assemblies of the second generation. For simulation of fuel loadings the computer code package SAPFIR 9 5 and RC is used that allows for correct consideration of specific features of assemblies design changes. The methodical approach to assessment of effectiveness of implementing the axial profiling is considered with the use of capabilities of the mentioned code package. In conclusion the recommendations are given on using the fuel enrichment axial profiling in WWER-440 assemblies (Authors)
Organo-axial volvulus of the small intestine: radiological case report and consideration for its mechanism.
Ishiguro, Toshitaka; Hiyama, Takashi; Nasu, Katsuhiro; Akashi, Yoshimasa; Minami, Manabu
Gastrointestinal volvulus is mainly classified into two subtypes, mesentero-axial volvulus and organo-axial volvulus. The detailed imaging findings of organo-axial volvulus of the small intestine have never been reported as far as we know. In this article, we report a case of organo-axial volvulus of the small intestine, focusing on the computed tomography (CT) findings. An 80-year-old man was radiologically diagnosed as having organo-axial volvulus of the terminal ileum and it was confirmed by open surgery without adhesion or any other anatomical abnormalities. CT showed two specific findings, split-bowel sign and rotating-C sign, which we think reflect pathophysiologic features of organo-axial volvulus. We think the pathogenic mechanism of organo-axial volvulus can be explained by the convergence of the reversed-rotational twist following the formation of a twisted but non-obstructive circular loop, even if there is no adhesion. Radiologists should be aware that organo-axial volvulus can occur even in the small intestine, and in the case of small bowel obstruction with single transition point, the two pathophysiologic signs mentioned above must be looked for to diagnose the possibility of organo-axial volvulus.
Fuel rod with axial regions of annular and standard fuel pellets
International Nuclear Information System (INIS)
Freeman, T.R.
This patent describes a fuel rod for use in a nuclear reactor fuel assembly. It comprises: an elongated hollow cladding tube; a pair of end plugs connected to and sealing the cladding tube at opposite ends of thereof; and an axial stack of fuel pellets contained in and extending between the end plugs at the opposite ends of the tube, all of the fuel pellets contained in the tube being composed of fissile material being enriched above the level of natural enrichment; the fuel pellets in the stack thereof being provided in an arrangement of axial regions. The arrangement of axial regions including a pair of first axial regions defined respectively at the opposite ends of the pellet stack adjacent to the respective end plugs. The pellets in the first axial regions being identical in number and having annular configurations with an annulus of a first void size. The arrangement of axial regions also including another axial region defined between the first axial regions, some of the pellets in the another axial region having solid configurations
International Nuclear Information System (INIS)
Kakaria, B.K.
This 1994 survey of prospective markets for CANDU reactors discusses prospects in Turkey, Thailand, the Philippines, Korea, Indonesia, China and Egypt, and other opportunities, such as in fuel cycles and nuclear safety. It was concluded that foreign partners would be needed to help with financing
Sharpening Intertemporal Prospect Theory
Pushpa, Rathie; Carlos, Radavelli; Sergio, Da Silva
Prospect theory [4] of risky choices has been extended to encompass intertemporal choices [6]. Presentation of intertemporal prospect theory suffers from minor mistakes, however [2]. To clarify the theory we restate it and show further mistakes in current presentations ([6], [2]) of value and discount functions.
Atropisomerism: the effect of the axial chirality in bioactive compounds; Atropoisomerismo: o efeito da quiralidade axial em substancias bioativas
Energy Technology Data Exchange (ETDEWEB)
Santos, Anderson Rouge dos; Pinheiro, Alessandra Campbell; Sodero, Ana Carolina Renno; Cunha, Andrea Sousa da; Padilha, Monica Costa; Sousa, Priscila Mesquita de; Fontes, Silvia Paredes [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Quimica. Dept. de Quimica Organica; Veloso, Marcia Paranho [Universidade Federal de Alfenas, MG (Brazil); Fraga, Carlos Alberto Manssour [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Faculdade de Farmacia. Lab. de Avaliacao e Sintese de Substancias Bioativas (LASSBio)]. E-mail: firstname.lastname@example.com
Atropisomerism is a special kind of stereoisomeric relationship that arises from the freezing of a certain conformation of an organic molecule, associated with a high rotational barrier about a single covalent bond. Atropisomerism has been originally described in orto-functionalized biphenyl derivatives, but a lot of other organic functionalities can present this structural phenomenon, characterized by the presence of chiral properties in compounds that do not present classical stereogenic centers. Atropisomeric compounds, intermediates and catalysts have well-know importance in organic synthesis, but the influence of the axial chirality in substances able to modulate biological systems is still not very exploited in drug design and development. In this context, the present account describes the importance of this structural property in the medicinal chemistry of different classes of bioactive compounds or therapeutic agents, emphasizing how atropisomerism could affect the molecular recognition of a ligand or a prototype by the target bioreceptor. (author)
Visualization of bonding at an inclusion boundary using axial-shear strain elastography: a feasibility study
International Nuclear Information System (INIS)
Thitaikumar, Arun; Krouskop, Thomas A; Garra, Brian S; Ophir, Jonathan
Ultrasound elastography produces strain images of compliant tissues under quasi-static compression. In axial-shear strain elastography, the local axial-shear strain resulting from application of quasi-static axial compression to an inhomogeneous material is imaged. The overall hypothesis of this work is that the pattern of axial-shear strain distribution around the inclusion/background interface is completely determined by the bonding at the interface after normalization for inclusion size and applied strain levels, and that it is feasible to extract certain features from the axial-shear strain elastograms to quantify this pattern. The mechanical model used in this study consisted of a single stiff circular inclusion embedded in a homogeneous softer background. First, we performed a parametric study using finite-element analysis (FEA) (no ultrasound involved) to identify possible features that quantify the pattern of axial-shear strain distribution around an inclusion/background interface. Next, the ability to extract these features from axial-shear strain elastograms, estimated from simulated pre- and post-compression noisy RF data, was investigated. Further, the feasibility of extracting these features from in vivo breast data of benign and malignant tumors was also investigated. It is shown using the FEA study that the pattern of axial-shear strain distribution is determined by the degree of bonding at the inclusion/background interface. The results suggest the feasibility of using normalized features that capture the region of positive and negative axial-shear strain area to quantify the pattern of the axial-shear strain distribution. The simulation results showed that it was feasible to extract the features, as identified in the FEA study, from axial-shear strain elastograms. However, an effort must be made to obtain axial-shear strain elastograms with the highest signal-to-noise ratio (SNR asse ) possible, without compromising the resolution. The in vivo
Axial distribution of absorbed doses in fast neutron field at the RB reactor
International Nuclear Information System (INIS)
Sokcic-Kostic, M.; Pesic, M.; Antic, D.; Ninkovic, M.
The coupled fast thermal system CFTS at the RB reactor is created for obtaining fast neutron fields. The axial distribution of fast neutron flux density in its second configuration (CFTS-2) is measured. The axial distribution of absorbed doses is computed on the basis of mentioned experimental results. At the end these experimental and computed results are given. (Author)
Behaviour of a neutral particle with spin in an axial magnetic field
International Nuclear Information System (INIS)
Sorokin, S.V.; Ehpp, V.Ya.
Proceeding from the Tamm-Good equation taking into account the spin influence on motion trajectory, the neutral particle motion tracjectory and vector turn of spin polarizition in axial magnetic field have been found. The behaviour of a neutral particle possessing its own magnetic moment in an axially-symmetric stationary magnetic field is considered
Passive axial magnetic bearing with Halbach magnetized array in magnetically suspended control moment gyro application
International Nuclear Information System (INIS)
Sun Jinji; Ren Yuan; Fang Jiancheng
The paper presents a special configuration of passive axial magnetic bearing with segmented Halbach magnetized array in magnetically suspended control moment gyro (MSCMG). Peculiarity of presented passive axial magnetic bearing is its ability to provide angular stiffness so that it can produce gyro moment when it is used in MSCMG. The MSCMG with this passive axial magnetic bearing can efficiently reduce the power loss when it supplies gyro moment compared with the five degrees of freedom (5-DOF) MSCMG. The characteristics of the suspension force and stiffness of the passive axial magnetic bearing are studied using finite element method (FEM). The performance of the presented passive axial magnetic bearing with Halbach magnetized array is verified by a prototyped MSCMG. - Research highlights: → Passive axial magnetic bearing is used to provide angular stiffness. → Passive axial magnetic bearing is based on repulsion. → Layers Halbach magnetized array realizes higher stiffness per bearing volume. → Passive axial magnetic bearing can provide gyro moment in CMG. → Power loss of MSCMG with PMB does not increase when it provides gyro moment.
Clinical characteristics of importance to outcome in patients with axial spondyloarthritis
DEFF Research Database (Denmark)
Andreasen, Rikke Asmussen; Kristensen, Lars Erik; Ellingsen, Torkell
INTRODUCTION: Spondyloarthritis (SpA) is a heterogeneous spectrum of rheumatic diseases with either predominantly axial inflammatory symptoms of the spine and sacroiliac joints or predominantly peripheral arthritis. The two main entities of axial SpA (axSpA) are ankylosing spondylitis or non...
Cdx and Hox genes differentially regulate posterior axial growth in mammalian embryos
Young, Teddy; Rowland, Jennifer Elizabeth; van de Ven, Cesca; Bialecka, Monika; Novoa, Ana; Carapuco, Marta; van Nes, Johan; de Graaff, Wim; Duluc, Isabelle; Freund, Jean-Noël; Beck, Felix; Mallo, Moises; Deschamps, Jacqueline
Hox and Cdx transcription factors regulate embryonic positional identities. Cdx mutant mice display posterior body truncations of the axial skeleton, neuraxis, and caudal urorectal structures. We show that trunk Hox genes stimulate axial extension, as they can largely rescue these Cdx mutant
Guided wave propagation as a measure of axial loads in rails
CSIR Research Space (South Africa)
Loveday, PW
Full Text Available Guided wave propagation has been proposed as a means to monitor the axial loads in continuously welded railway rails although no practical system has been developed. In this paper, the influence of axial load on the guided wave propagation...
Constraining vectors and axial-vectors in walking technicolour by a holographic principle
DEFF Research Database (Denmark)
D. Dietrich, Dennis; Kouvaris, Christoforos
We use a holographic principle to study the low-energy spectrum of walking technicolour models. In particular, we predict the masses of the axial vectors as well as the decay constants of vectors and axial vectors as functions of the mass of the techni-rho. Given that there are very few...
Magmatic controls on axial relief and faulting at mid-ocean ridges
Liu, Zhonglan; Buck, W. Roger
Previous models do not simultaneously reproduce the observed range of axial relief and fault patterns at plate spreading centers. We suggest that this failure is due to the approximation that magmatic dikes open continuously rather than in discrete events. During short - lived events, dikes open not only in the strong axial lithosphere but also some distance into the underlying weaker asthenosphere. Axial valley relief affects the partitioning of magma between the lithosphere and asthenosphere during diking events. The deeper the valley, the more magma goes into lithospheric dikes in each event and so the greater the average opening rate of those dikes. The long-term rate of lithospheric dike opening controls faulting rate and axial depth. The feedback between axial valley depth D and lithospheric dike opening rate allows us to analytically relate steady-state values of D to lithospheric thickness HL and crustal thickness HC. A two-dimensional model numerical model with a fixed axial lithospheric structure illustrates the analytic model implications for axial faulting. The predictions of this new model are broadly consistent with global and segment-scale trends of axial depth and fault patterns with HL and HC.
A benchmark study of procedures for analysis of axial crushing of bulbous bows
DEFF Research Database (Denmark)
Yamada, Yasuhira; Pedersen, Preben Terndrup
Simplified methods to estimate mean axial crushing forces of plated structures are reviewed and applied to a series of experimental results for axial crushing of large-scale bulbous bow models. Methods based on intersection unit elements such as L-, T- and X-type elements as well as methods based...
Molecular design for nonpolar chiral-axial quadratic nonlinear optics
Wiggers, Gregory A.
In this thesis the hyperpolarizability of various multi-dimensional molecules is studied theoretically/computationally, with particular focus on the second-rank Kleinman-disallowed (KD) component of the hyperpolarizability. This component, which transforms as a second-rank traceless symmetric tensor, could be utilized in certain chiral-axial molecular alignment schemes to produce a bulk response. Nonpolar chiral-axial systems have been proposed in contrast to polar media, which utilize the vector component of the molecular hyperpolarizability and require parallel alignment of the molecular dipoles. Such parallel alignment of dipoles must be "frozen in" in order to overcome the natural tendency for dipoles to align anti-parallel. This limits the density of chromophores that can be loaded into a polar material. Nonpolar materials do not have such limits in theory. The two geometric classes of molecules that can most easily be incorporated into nonpolar chiral-uniaxial materials are propeller-shaped (C3 or D3 symmetry) and Λ-shaped (C2v symmetry). This work describes efforts to design molecules within these classes that would be suitable for bulk NLO materials. The sum-over-states (SOS) expression is used to model the molecular hyperpolarizability, and quantum chemical calculations, along with linear absorption data (when available) provide the necessary parameters to evaluate truncated forms of the SOS expression. A host of chemical and geometric modifications will be considered in order to elucidate important structure/function relationships. Also, the SOS model will be tested in some cases when experimental measurements (via Kleinman-disallowed hyper-Rayleigh scattering) are available. While a majority of this work focuses on multi-dimensional molecules, a small section deals with the question of optimizing the hyperpolarizability of a one-dimensional system. It is suggested that the recently-proposed idea of "modulated conjugation" as a means for improving
NASA Glenn's Single-Stage Axial Compressor Facility Upgraded
Brokopp, Richard A.
NASA Glenn Research Center's Single-Stage Axial Compressor Facility was upgraded in fiscal year 2003 to expand and improve its research capabilities for testing high-speed fans and compressors. The old 3000-hp drive motor and gearbox were removed and replaced with a refurbished 7000-hp drive motor and gearbox, with a maximum output speed of 21,240 rpm. The higher horsepower rating permits testing of fans and compressors with higher pressure ratio or higher flow. A new inline torquemeter was installed to provide an alternate measurement of fan and compressor efficiency, along with the standard pressure and temperature measurements. A refurbished compressor bearing housing was also installed with bidirectional rotation capability, so that a variety of existing hardware could be tested. Four new lubrication modules with backup capability were installed for the motor, gearbox, torquemeter, and compressor bearing housing, so that in case the primary pump fails, the backup will prevent damage to the rotating hardware. The combustion air supply line for the facility inlet air system was activated to provide dry air for repeatable inlet conditions. New flow conditioning hardware was installed in the facility inlet plenum tank, which greatly reduced the inlet turbulence. The new inlet can also be easily modified to accommodate 20- or 22-in.-diameter fans and compressors, so a variety of existing hardware from other facilities (such as Glenn's 9- by 15-Foot Low-Speed Wind Tunnel) can be tested in the Single-Stage Axial Compressor Facility. An exhaust line was also installed to provide bleed capability to remove the inlet boundary layer. To improve the operation and control of the facility, a new programmable logic controller (PLC) was installed to upgrade from hardwired relay logic to software logic. The PLC also enabled the usage of human-machine interface software to allow for easier operation of the facility and easier reconfiguration of the facility controls when
Topological invariants and the dynamics of an axial vector torsion field
International Nuclear Information System (INIS)
Drechsler, W.
A generalized throry of gravitation is discussed which is based on a Riemann-Cartan space-time, U 4 , with an axial vector torsion field. Besides Einstein's equations determining the metric of the U 4 a system of nonlinear field equations is established coupling an axial vector source current to the axial vector torsion field. The properties of the solutions of these equations are discussed assuming a London-type condition relating the axial current and torsion field. To characterize the solutions use is made of the Euler and Pontrjagin forms and the associated quadratic curvature invariants for the U 4 space-time. It is found that there exists for a Riemann-Cartan space-time a relation between the zeros of the axial vector torsion field and the singularities of the Pontrjagin invariant, which is analogous to the well-known Hopf relation between the zeros of vector fields and the Euler characteristic. (author)
Efficient Propulsion Structure with an Axial Flux Rotary Converter for HEV Drive Unit
Directory of Open Access Journals (Sweden)
Ales Havel
Full Text Available This paper describes an efficient axial flux arrangement of the four quadrant rotary converter for hybrid electric vehicles. The design of the axial flux wound stator and both axial flux squirrel cage rotors is based on the arrangement of radial air gap induction motor and permanent magnet synchronous motor. The method of constant magnetic circuit volume is utilized for dimensions conversion, which results into basic dimensions of stator and rotor discs in axial flux conception. This allows the creation of real 3D models in the CAD application. Finally, the finite element simulations of electromagnetic induction in the axial flux stator pack are presented in the concluding part of this paper.
What changed during the axial age: Cognitive styles or reward systems?
Baumard, Nicolas; Hyafil, Alexandre; Boyer, Pascal
The 'Axial Age' (500–300 BCE) refers to the period during which most of the main religious and spiritual traditions emerged in Eurasian societies. Although the Axial Age has recently been the focus of increasing interest,1-5 its existence is still very much in dispute. The main reason for questioning the existence of the Axial Age is that its nature, as well as its spatial and temporal boundaries, remain very much unclear. The standard approach to the Axial Age defines it as a change of cognitive style, from a narrative and analogical style to a more analytical and reflective style, probably due to the increasing use of external memory tools. Our recent research suggests an alternative hypothesis, namely a change in reward orientation, from a short-term materialistic orientation to a long-term spiritual one.6 Here, we briefly discuss these 2 alternative definitions of the Axial Age. PMID:27066164
Utility of axial images in an early Alzheimer disease diagnosis support system (VSRAD)
International Nuclear Information System (INIS)
Goto, Masami; Aoki, Shigeki; Abe, Osamu
In recent years, voxel-based morphometry (VBM) has become a popular tool for the early diagnosis of Alzheimer disease. The Voxel-Based Specific Regional Analysis System for Alzheimer's Disease (VSRAD), a VBM system that uses MRI, has been reported to be clinically useful. The able-bodied person database (DB) of VSRAD, which employs sagittal plane imaging, is not suitable for analysis by axial plane imaging. However, axial plane imaging is useful for avoiding motion artifacts from the eyeball. Therefore, we created an able-bodied person DB by axial plane imaging and examined its utility. We also analyzed groups of able-bodied persons and persons with dementia by axial plane imaging and reviewed the validity. After using the DB of axial plane imaging, the Z-score of the intrahippocampal region improved by 8 in 13 instances. In all brains, the Z-score improved by 13 in all instances. (author)
Tunable axial gauge fields in engineered Weyl semimetals: semiclassical analysis and optical lattice implementations
Roy, Sthitadhi; Kolodrubetz, Michael; Goldman, Nathan; Grushin, Adolfo G.
In this work, we describe a toolbox to realize and probe synthetic axial gauge fields in engineered Weyl semimetals. These synthetic electromagnetic fields, which are sensitive to the chirality associated with Weyl nodes, emerge due to spatially and temporally dependent shifts of the corresponding Weyl momenta. First, we introduce two realistic models, inspired by recent cold-atom developments, which are particularly suitable for the exploration of these synthetic axial gauge fields. Second, we describe how to realize and measure the effects of such axial fields through center-of-mass observables, based on semiclassical equations of motion and exact numerical simulations. In particular, we suggest realistic protocols to reveal an axial Hall response due to the axial electric field \
Dispersion relation and growth rate in a Cherenkov free electron laser: Finite axial magnetic field
International Nuclear Information System (INIS)
Kheiri, Golshad; Esmaeilzadeh, Mahdi
A theoretical analysis is presented for dispersion relation and growth rate in a Cherenkov free electron laser with finite axial magnetic field. It is shown that the growth rate and the resonance frequency of Cherenkov free electron laser increase with increasing axial magnetic field for low axial magnetic fields, while for high axial magnetic fields, they go to a saturation value. The growth rate and resonance frequency saturation values are exactly the same as those for infinite axial magnetic field approximation. The effects of electron beam self-fields on growth rate are investigated, and it is shown that the growth rate decreases in the presence of self-fields. It is found that there is an optimum value for electron beam density and Lorentz relativistic factor at which the maximum growth rate can take place. Also, the effects of velocity spread of electron beam are studied and it is found that the growth rate decreases due to the electron velocity spread
[Utility of axial images in an early Alzheimer disease diagnosis support system (VSRAD)].
Goto, Masami; Aoki, Shigeki; Abe, Osamu; Masumoto, Tomohiko; Watanabe, Yasushi; Satake, Yoshiroh; Nishida, Katsuji; Ino, Kenji; Yano, Keiichi; Iida, Kyohhito; Mima, Kazuo; Ohtomo, Kuni
In recent years, voxel-based morphometry (VBM) has become a popular tool for the early diagnosis of Alzheimer disease. The Voxel-Based Specific Regional Analysis System for Alzheimer's Disease (VSRAD), a VBM system that uses MRI, has been reported to be clinically useful. The able-bodied person database (DB) of VSRAD, which employs sagittal plane imaging, is not suitable for analysis by axial plane imaging. However, axial plane imaging is useful for avoiding motion artifacts from the eyeball. Therefore, we created an able-bodied person DB by axial plane imaging and examined its utility. We also analyzed groups of able-bodied persons and persons with dementia by axial plane imaging and reviewed the validity. After using the DB of axial plane imaging, the Z-score of the intrahippocampal region improved by 8 in 13 instances. In all brains, the Z-score improved by 13 in all instances.
An axial calculation method for accurate two-dimensional PWR core simulation
International Nuclear Information System (INIS)
Grimm, P.
An axial calculation method, which improves the agreement of the multiplication factors determined by two- and three-dimensional PWR neutronic calculations, is presented. The axial buckling is determined at each time point so as to reproduce the increase of the leakage due to the flattening of the axial power distribution and the effect of the axial variation of the group constants of the fuel on the reactivity is taken into account. The results of a test example show that the differences of k-eff and cycle length between two- and three-dimensional calculations, which are unsatisfactorily large if a constant buckling is used, become negligible if the results of the axial calculation are used in the two-dimensional core simulation. (Auth.)
Referral patterns, diagnosis, and disease management of patients with axial spondyloarthritis: results of an international survey.
van der Heijde, Désirée; Sieper, Joachim; Elewaut, Dirk; Deodhar, Atul; Pangan, Aileen L; Dorr, Alexander P
Recognition, diagnosis, and management of axial spondyloarthritis (axial SpA) continue to advance. The objectives of this study were to compare referrals, diagnosis, and management of axial SpA in Western Europe (WE), North America (US and Canada), and the rest of world (RoW) in academic and community rheumatology practices and to identify areas for further education. Rheumatologists responded online to the MAXIMA (Management of Axial SpA International and Multicentric Approaches) survey. Questions pertained to referral, diagnosis, and management of axial SpA. Rheumatologists (N = 809) from 56 countries completed the survey about patients with chronic back pain (≥3 months) starting before age 45 years. Responses from academic and community practice rheumatologists were generally similar. Most referrals were from primary care providers. Symptom duration of 3 years or more at referral was reported more frequently by WE and RoW than US respondents. More WE and RoW than US rheumatologists referred to the Assessment of SpondyloArthritis International Society criteria for axial SpA in clinical practice. Rheumatologists reported prescribing disease-modifying antirheumatic drugs for the management of axial SpA. Sulfasalazine was frequently prescribed across regions; methotrexate was more commonly prescribed by US rheumatologists compared with other regions. Referral patterns, diagnosis, and disease management for axial SpA were similar among WE, North America, and RoW rheumatologists and in academic/community practices, although more WE and RoW rheumatologists referred to Assessment of SpondyloArthritis International Society criteria in clinical practice. Disease-modifying antirheumatic drugs were commonly prescribed for axial SpA patients, although it was unclear whether these were prescribed for axial or peripheral symptoms.
A High Torque Density Axial Flux SRM with Modular Stator
Directory of Open Access Journals (Sweden)
Y Ebrahimi
Full Text Available A novel structure of switched reluctance motors (SRMs is proposed. The proposed structure uses the benefits of the axial flux path, short flux path, segmental rotor, and flux reversal free stator motors all together to improve the torque density of the SRMs. The main geometrical, electrical and physical specifications are presented. In addition, some features of the proposed structure are compared with those of a state-of-the-art radial flux SRM, considered as a reference motor. Then, the proposed structure is modified by employing a higher number of rotor segments than the stator modules and at the same time, reshaped stator modules tips. Achieved results reveal that, compared with the reference motor, the proposed and the modified proposed motors deliver about the same torque with 36.5% and 46.7% lower active material mass, respectively. The efficiency and torque production capability for the extended current densities are also retained. These make the proposed structures a potentially proper candidate for the electric vehicles (EVs and hybrid electric vehicles (HEVs as an in-wheel motor.
Axial focusing of energy from a hypervelocity impact on earth
International Nuclear Information System (INIS)
Boslough, M.B.; Chael, E.P.; Trucano, T.G.; Crawford, D.A.
We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth's surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth's interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes
A parametric study of axial segregation in a rotating cylinder.
Energy Technology Data Exchange (ETDEWEB)
Bielenberg, J. R. (James R.); Gladysz, G. M. (Gary M.); Graham, Alan L.
When a cylindrical container, partially filled with a binary granular mixture of particles that differ in size or density, is rotated around its axis, a spontaneous segregation of the two granular components may occur. In order to better understand this phenomena, we have carried out an experimental study probing the effect of average particle size and relative size difference between particles on the onset of segregation. The experimental study is followed by a novel scaling analysis that relates the deterministic, convective driving force for particle segregation to the randomizing diffusional driving force present in these systems through the definition of an axial granular Peclet number. This Peclet number based approach will forgo some of the difficulties inherent in full-scale dynamic simulations, but will still allow us to determine the effects of system parameters on the final steady-state that is achieved. Values of this granular Peclet number are shown to successfully correlate with segregation behavior in the present experiment results, as well as in comparable results present in the literature.
Inverted relativistic magnetron with a single axial output
International Nuclear Information System (INIS)
Ballard, W.P.; Earley, L.M.; Wharton, C.B.
A twelve vane, 1 MV, S-band magnetron has been designed and tested. An inverted design was selected to minimize the parasitic axial electron losses. The stainless steel anode is approximately one wavelength long. One end is partially short-circuited to rf, while the other end has a mode transformer to couple the 3.16 GHz π-mode out into a TM 01 circular waveguide. The magnetron has a loaded output Q of about 100. Operation at 1 MV, 0.31 T, 5 kA routinely produces approx.150 MW peak rms and 100 MW average rms with pulse lengths adjustable from 5 to 70 ns. The microwave power pulse has a rise time of approx.2 ns. The output power is diagnosed using four methods: calorimetry, two circular-waveguide directional couplers installed on the magnetron, two transmitting-receiving systems, and gaseous breakdown. Operation at other voltages and magnetic fields shows that the oscillation frequency is somewhat dependent on the magnetron current. Frequency changes of approx.20 MHz/kA occur as the operating conditions are varied. A series of experiments varying the anode conductivity, the electron emission profile, and the output coupling transformer design showed that none of these significantly increased the output power. Therefore, we have concluded that this magnetron operates in saturation. Because of the anode lifetime and repeatability, this magnetron has the potential to be repetitively pulsed. 36 refs., 16 figs
Conservative management of extra-axial hematomas diagnosed by CT
International Nuclear Information System (INIS)
Muszynski, C.A.; Hayman, L.A.; Weingarten, K.; Prow, H.W.; Cole, J.W.; Contant, C.F.
Our purpose was to assess the role of serial CT in recently traumatized patients with clinically stable extra-axial intracranial hematomas (EACH) and a midline shift of less than 0.5 cm. A retrospective review of 91 imaging studies in 41 patients (with 45 EACH) was done to assess the time between trauma and CT; the presence and type of skull fracture; the volume, type, and location of the EACH; the presence of associated edema and/or contusion. Over a 19-day follow-up, 11 % of the dense EACH increased in volume and 27 % decreased. An adjacent skull fracture was seen most frequently in patients with a decrease in EACH volume. Clinical data remain the key to determining the need for neurosurgical intervention in patients with EACH. Follow-up CT afforded no data which altered the medical management of these patients. However, it may be said to have alerted the clinician to an increase in the size of the EACH in 11 % of cases, which could mandate close observation of this group. (orig.)
Meissner effect for axially symmetric charged black holes
Gürlebeck, Norman; Scholtz, Martin
In our previous work [N. Gürlebeck and M. Scholtz, Phys. Rev. D 95, 064010 (2017), 10.1103/PhysRevD.95.064010], we have shown that electric and magnetic fields are expelled from the horizons of extremal, stationary and axially symmetric uncharged black holes; this is called the Meissner effect for black holes. Here, we generalize this result in several directions. First, we allow that the black hole carries charge, which requires a generalization of the definition of the Meissner effect. Next, we introduce the notion of almost isolated horizons, which is weaker than the usual notion of isolated horizons, since the geometry of the former is not necessarily completely time independent. Moreover, we allow the horizon to be pierced by strings, thereby violating the usual assumption on the spherical topology made in the definition of the weakly isolated horizon. Finally, we spell out in detail all assumptions entering the proof and show that the Meissner effect is an inherent property of black holes even in full nonlinear theory.
Axial focusing of energy from a hypervelocity impact on earth
Energy Technology Data Exchange (ETDEWEB)
Boslough, M.B.; Chael, E.P.; Trucano, T.G.; Crawford, D.A.
We have performed computational simulations to determine how energy from a large hypervelocity impact on the Earth`s surface would couple to its interior. Because of the first-order axial symmetry of both the impact energy source and the stress-wave velocity structure of the Earth, a disproportionate amount of energy is dissipated along the axis defined by the impact point and its antipode (point opposite the impact). For a symmetric and homogeneous Earth model, all the impact energy that is radiated as seismic waves into the Earth at a given takeoff angle (ray parameter), independent of azimuthal direction, is refocused (minus attenuation) on the axis of symmetry, regardless of the number of reflections and refractions it has experienced. Material on or near the axis of symmetry experiences more strain cycles with much greater amplitude than elsewhere, and therefore experiences more irreversible heating. The focusing is most intense in the upper mantle, within the asthenosphere, where seismic energy is most effectively converted to heat. For a sufficiently energetic impact, this mechanism might generate enough local heating to create an isostatic instability leading to uplift, possibly resulting in rifting, volcanism, or other rearrangement of the interior dynamics of the planet. These simulations demonstrate how hypervelocity impact energy can be transported to the Earth`s interior, supporting the possibility of a causal link between large impacts on Earth and major internally-driven geophysical processes.
Strength and dynamic characteristics analyses of wound composite axial impeller
Wang, Jifeng; Olortegui-Yume, Jorge; Müller, Norbert
A low cost, light weight, high performance composite material turbomachinery impeller with a uniquely designed blade patterns is analyzed. Such impellers can economically enable refrigeration plants to use water as a refrigerant (R718). A strength and dynamic characteristics analyses procedure is developed to assess the maximum stresses and natural frequencies of these wound composite axial impellers under operating loading conditions. Numerical simulation using FEM for two-dimensional and three-dimensional impellers was investigated. A commercially available software ANSYS is used for the finite element calculations. Analysis is done for different blade geometries and then suggestions are made for optimum design parameters. In order to avoid operating at resonance, which can make impellers suffer a significant reduction in the design life, the designer must calculate the natural frequency and modal shape of the impeller to analyze the dynamic characteristics. The results show that using composite Kevlar fiber/epoxy matrix enables the impeller to run at high tip speed and withstand the stresses, no critical speed will be matched during start-up and shut-down, and that mass imbalances of the impeller shall not pose a critical problem.
Axial ion channeling patterns from ultra-thin silicon membranes
International Nuclear Information System (INIS)
Motapothula, M.; Dang, Z.Y.; Venkatesan, T.; Breese, M.B.H.; Rana, M.A.; Osman, A.
We present channeling patterns produced by MeV protons transmitted through 55 nm thick [0 0 1] silicon membranes showing the early evolution of the axially channeled beam angular distribution for small tilts away from the [0 0 1], [0 1 1] and [1 1 1] axes. Instead of a ring-like "doughnut" distribution previously observed at small tilts to major axes in thicker membranes, geometric shapes such as squares and hexagons are observed along different axes in ultra-thin membranes. The different shapes arise because of the highly non-equilibrium transverse momentum distribution of the channeled beam during its initial propagation in the crystal and the reduced multiple scattering which allows the fine angular structure to be resolved. We describe a simple geometric construction of the intersecting planar channels at an axis to gain insight into the origin of the geometric shapes observed in such patterns and how they evolve into the 'doughnut' distributions in thicker crystals.
Axial transport of fission gas in LWR fuel rods
International Nuclear Information System (INIS)
Kinoshita, M.
With regard to fission gas transportation inside the fuel rod, the following three mechanisms are important: (1) a localized and time dependent fission gas release from UO 2 fuel to pellet/clad gap, (2) the consequent gas pressure difference between the gap and the plenum, and (3) the inter-diffusion of initially filled Helium and released fission gas such as Xenon. Among these three mechanisms, the 2nd mechanism would result in the one dimensional flow through P/C gap in the axial direction, while the 3rd would average the local fission gas concentration difference. In this paper, an attempt was made to develop a computerized model, LINUS (LINear flow and diffusion under Un-Steady condition) describing the above two mechanisms, items (2) and (3). The item (1) is treated as an input. The code was applied to analyse short length experimental fuel rods and long length commercial fuel rods. The calculated time evolution of Xe concentration along the fuel column shows that the dilution rate of Xe in commercial fuel rods is much slower than that in short experimental fuel rods. Some other sensitivity studies, such as the effect of pre-pressurization, are also presented. (author)
XBWR, 1-D Xe Transients for BWR in Axial Geometry
International Nuclear Information System (INIS)
Forti, G.
1 - Nature of the physical problem solved: 1-D xenon transients for BWRs in axial geometry. 2 - Method of solution: XBWR couples a two group neutron diffusion calculation in plane geometry with a two phase flow cooling channel calculation and the heat conduction in the typical fuel rod. The program allows following any given power time schedule, such as shut-down and restart, day-night power variation etc., while the reactor is being kept critical by control rod movement, variable poisoning of the core, or coolant flow recirculation rate. The xenon and iodine concentrations variation is evaluated pointwise (up to 100 points) by analytical solution for successive fixed time steps. At the end of each time step a new distribution of fluxes, power, voids and temperatures is obtained, which is consistent with the reactor critical condition as it is got by variation of the control parameter taking into account the feedbacks. The new flux distribution is used as input for xenon and iodine concentrations evolution in the next time step
Axial Compressive Strength of Foamcrete with Different Profiles and Dimensions
Directory of Open Access Journals (Sweden)
Othuman Mydin M.A.
Full Text Available Lightweight foamcrete is a versatile material; primarily consist of a cement based mortar mixed with at least 20% volume of air. High flow ability, lower self-weight, minimal requirement of aggregate, controlled low strength and good thermal insulation properties are a few characteristics of foamcrete. Its dry densities, typically, is below 1600kg/m3 with compressive strengths maximum of 15MPa. The ASTM standard provision specifies a correction factor for concrete strengths of between 14 and 42MPa to compensate for the reduced strength when the aspect height-to-diameter ratio of specimen is less than 2.0, while the CEB-FIP provision specifically mentions the ratio of 150 x 300mm cylinder strength to 150 mm cube strength. However, both provisions requirements do not specifically clarify the applicability and/or modification of the correction factors for the compressive strength of foamcrete. This proposed laboratory work is intended to study the effect of different dimensions and profiles on the axial compressive strength of concrete. Specimens of various dimensions and profiles are cast with square and circular cross-sections i.e., cubes, prisms and cylinders, and to investigate their behavior in compression strength at 7 and 28 days. Hypothetically, compressive strength will decrease with the increase of concrete specimen dimension and concrete specimen with cube profile would yield comparable compressive strength to cylinder (100 x 100 x 100mm cube to 100dia x 200mm cylinder.
Lateral atlanto-axial joint block for cervical headache
Directory of Open Access Journals (Sweden)
Shantanu P Mallick
Full Text Available The patient is a 32-year-old car mechanic, having chronic headache for three years affecting the left upper lateral part of the neck, suboccipital region, and scalp (VAS: 8/10, having a history of whiplash injury from a car accident three years ago, with a deep cut injury on the scalp. He was complaining of neck stiffness and pain during all neck movements and a burning pain in the entire left side of the neck and scalp. He was treated, using conservative methods, by Orthopedists, Neurologists, as well as Psychiatrists, and all investigations including computed tomography (CT of the brain, X-ray cervical spine, and all related blood reports were within normal limits. He was sent to the Pain Clinic for further assessment. Suspecting sympathetic mediated pain on the left side and upper cervical facet pain, he was given a diagnostic Stellate Ganglion Block, a Third Occipital Nerve block, and a fourth cervical medial branch block (MBB, which gave him good relief; by this the visual analog scale (VAS score reduced to 3/10. Yet, he was complaining of pain on a focal area on the left upper cervical spine corresponding to the C1-2 joint with lateral rotation on the left side. Subsequently it was decided that a diagnostic Atlanto-axial joint block under fluoroscopy would be carried out. This gave him very good relief from the cervicogenic headache.
Numerical optimisation of an axial turbine; Numerische Optimierung einer Axialturbine
Energy Technology Data Exchange (ETDEWEB)
Welzel, B.
The author presents a method for automatic shape optimisation of components with internal or external flow. The method combines a program for numerical calculation of frictional turbulent flow with an optimisation algorithm. Algorithms are a simplex search strategy and an evolution strategy. The shape of the component to be optimized is variable due to shape parameters modified by the algorithm. For each shape, a flow calculation is carried out on whose basis a functional value like performance, loss, lift or resistivity is calculated. For validation, the optimisation method is used in simple examples with known solutions. It is applied. It is applied to the components of a slow-running axial turbine. Components with accelerated and delayed rotationally symmetric flow and 2D blade profiles are optimized. [Deutsch] Es wird eine Methode zur automatischen Formoptimierung durchstroemter oder umstroemter Bauteile vorgestellt. Diese koppelt ein Programm zur numerischen Berechnung reibungsbehafteter turbulenter Stroemungen mit einem Optimierungsalgorithmus. Dabei kommen als Algorithmen eine Simplex-Suchstrategie und eine Evolutionsstrategie zum Einsatz. Die Form des zu optimierenden Koerpers ist durch Formparameter, die vom Algorithmus veraendert werden, variabel. Fuer jede Form wird eine Stroemungsberechnung durchgefuehrt und mit dieser ein Funktionswert wie Wirkungsgrad, Verlust, Auftrieb oder Widerstandskraft berechnet. Die Optimierungsmethode wird zur Validierung in einfachen Beispielen mit bekannter Loesung eingesetzt. Zur Anwendung kommt sie in den einzelnen Komponenten einer langsamlaeufigen Axialturbine. Es werden Bauteile mit beschleunigter und verzoegerter rotationssymmetrischer Stroemung und 2D-Schaufelprofile optimiert. (orig.)
Effective axial-vector strength and β-decay systematics
Delion, D. S.; Suhonen, J.
We use the weak axial-vector coupling strength g_{\\text{A}} as a key parameter to reproduce simultaneously the available data for both the Gamow-Teller \\beta^- and \\beta^+/\\text{EC} decay rates in nine triplets of isobars with mass numbers A=70,78,100,104,106,110,116,128,130 . We use the proton-neutron quasiparticle random-phase approximation (pnQRPA) with schematic dipole interaction containing particle-particle and particle-hole parts with mass-dependent strengths. Our analysis points to a strongly quenched effective value g_{\\text{A}}\\approx 0.3 , with a relative error of 28%. We then perform a systematic computation of 218 experimentally known \\beta^- and \\beta^+/\\text{EC} decays with quite a remarkable success. The presently extracted value of g_{\\text{A}} should be taken as an effective one, specific for a given nuclear theory framework. Present studies suggest that the effective g_{\\text{A}} is suitable for the description of decay transitions to 1^+ states at moderate excitation, below the Gamow-Teller giant resonance region.
Experiments on the Taylor system with an axial flow
International Nuclear Information System (INIS)
Tsameret, Avraham.
This work is an experimental study of the Taylor system with a superimposed axial flow. The convective and absolute instability lines which are associated with the propagating Taylor vortices are measured. A quantitative agreement is found with the theoretical predictions. Noise-sustained structures are found to exist in the convectively unstable region, above a critical value of the through flow. These structures are propagating Taylor vortices that are characterized by a noisy power spectrum and irregular temporal dynamics of velocity amplitude. At the absolute instability line the power spectrum of the propagating Taylor vortices exhibits transition to a sharp peak, and the amplitude of the propagating Taylor vortices becomes stationary. The mechanism that generates the noise-sustained structures is identified with a process of permanent amplification of noise that is generated mainly near the inlet boundary. The intrinsic noise in the system is studied. This study is motivated by the question of whether the noise which generates the noise-sustained structures is thermal. The intensity of the intrinsic noise is estimated by several methods, which includes a comparison of data with numerical simulations of the amplitude equation with a noise term. It is found that the intrinsic noise is not thermal, although its intensity reaches the thermal noise level at small through-flow velocities. Novel states are manifested in the system as a result of interaction between the propagating Taylor vortices and spiral modes. These states are studied and their spatial and temporal properties are analyzed. (author)
Complementary medicine for axial spondyloarthritis: is there any scientific evidence?
Danve, Abhijeet; Deodhar, Atul
Majority of patients with axial spondyloarthritis (axSpA) report use of complementary and alternative medicine (CAM) therapies before and even after the diagnosis, due to perceived efficacy and wide-spread belief that these modalities lack side effects. In this review, we describe the available scientific evidence for the CAM therapies in axSpA. Clinical trials of the CAM therapies in axSpA are generally hampered by small sample size, short duration, difficulties in blinding, lack of control groups and strong placebo effect. Nonetheless, exercise programs like Pilates and mind-body techniques such as Tai Chi may have favorable effect on the disease activity and function. Although not yet confirmed, the modulation of the microbiome with the help of probiotics or fecal transplant has face validity given the evolving scientific rationale. Diet has only limited role in the management of axSpA. Deep tissue massage, omega-3 fatty acids and Stanger bath were found to be useful in small studies. CAM therapies are not always entirely well tolerated, particularly the manipulative techniques like chiropractic and Tui-na in patients with advanced disease and osteoporosis. There are no trials of yoga in axSpA despite the wider acceptance and use of yoga as an effective mind-body technique. Larger and better quality clinical trials of CAM therapies are needed to confirm their efficacy and safety in the management of axSpA and to include them in the 'mainstream' medicine.
Military boot attenuates axial loading to the lower leg.
Yoganandan, Narayan; Schlick, Michael; Arun, Mike W J; Pintar, Frank A
Biomechanical tests to understand injury mechanisms and derive injury tolerance information using Post-Mortem Human Subjects (PMHS) have not used foot protection and they have primarily focused on civilian environments such as automotive and athletic- and sports-related events. As military personnel use boots, tests with the boot are required to understand their effect on attenuating lower leg loads. The purpose of this study was therefore, to determine the modulation of human lower leg kinematics with boot compressions and share of the force absorbed by the boot from underbody blast loading. Axial impacts were delivered to the Hybrid III dummy lower leg in the neutral position. The dummy leg was instrumented with its internal upper and lower tibia load cells, and in addition, a knee load cell was attached to the proximal end. Tests were conducted at 4.4 to 8.9 m/s, with and without boots, and repeat tests were done. Morphologies of the force-time responses were similar at the three load cell locations and for all input combinations and booted and unbooted conditions. However, booted tests resulted in considerably lower maximum forces (approximately two-third reduction) than unbooted tests. These results clearly show that boots can absorb a considerable share of the impact energy and decrease impact loads transmitted to the lower leg under vertical loading, thus necessitating the generation of tolerance data using PMHS for this environment.
Shape Manifestation of Respiration in the Axial System
Directory of Open Access Journals (Sweden)
Eliška Slawiková
Full Text Available Shape Manifestation of Respiration in the Axial System The aim of the study was to evaluate the effect of respiration on the shape changes of the axial system. Our approach focuses more on the analysis of respiratory function and their implementation within the complex axial system – the trunk. The results of this pilot study will use as evidence for further study of relationship between respiration and physiotherapy. Now we are looking for an answer to the question, at what level of the human body reflected the influence of respiration and its use in physiotherapy. This pilot study was attended by two women and one man aged 25–40 years, who were not selected for the study according to predetermined conditions. The same characteristic features of all three prarticipants were sedentary job connected with excessive mental strain, occasional low back pain (usually after a long sitting and the absence of acute or chronic respiratory diseases. Another common feature of the participants was the absence of structural changes in the spine. During the experiment was monitored maximum inhalation and maximum exhalation, and respiratory maneuver Kapalabhati, often used as one of the basic yoga breathing exercises. To detect trunk movement during the respiratory maneuver, we opted for a Qualysis – 3D torso topography. At the same time spirometer panned changes in volume over time, both exhaled and inhaled air. The purpose of this study was to assess symptoms and implementation of respiratory maneuvers in the axial system, particularly the chest and abdominal area. During the experiment, we followed the differences in reaction of the chest and abdomen in respiratory maneuver in the direction vertical, antero-posterior and lateral. The difference in these indicators at different phases of the respiratory maneuver confirms our assumption of the possibility of influencing the selected folders axial system through appropriately selected respiratory maneuver
Status and prospects for the calculation of hadron structure from lattice QCD
International Nuclear Information System (INIS)
Renner, Dru B.
Lattice QCD calculations of hadron structure are a valuable complement to many experimental programs as well as an indispensable tool to understand the dynamics of QCD. I present a focused review of a few representative topics chosen to illustrate both the challenges and advances of our community: the momentum fraction, axial charge and charge radius of the nucleon. I will discuss the current status of these calculations and speculate on the prospects for accurate calculations of hadron structure from lattice QCD. (orig.)
Czech Academy of Sciences Publication Activity Database
Steiner, Jakub; Stewart, C.
Roč. 106, č. 7 (2016), s. 1601-1631 ISSN 0002-8282 Institutional support: RVO:67985998 Keywords : evolution * perception bias * prospect theory Subject RIV: AH - Economics Impact factor: 4.026, year: 2016
Target localization on standard axial images in computed tomography (CT) stereotaxis for functional neurosurgery - a technical note
International Nuclear Information System (INIS)
Patil, A.-A.
A simple technique for marking functional neurosurgery target on computed tomography (CT) axial image is described. This permits the use of standard axial image for computed tomography (CT) stereotaxis in functional neurosurgery. (Author)
Antibodies to Mutated Citrullinated Vimentin in Rheumatoid Arthritis: Diagnostic Value, Association with Radiological Damage and Axial Skeleton Affection
Directory of Open Access Journals (Sweden)
Howaida E. Mansour
Full Text Available Abstract Background: Early definitive diagnosis and effective treatment are mandatory in rheumatoid arthritis (RA as it can halt the disease progression and subsequent joints destruction. Objective: To investigate the diagnostic and prognostic value of anti-mutated citrullinated vimentin (anti-MCV and its correlation with disease activity, peripheral and axial skeleton affection in RA patients. Patients and methods: A total of 123 patients with different rheumatic diseases were enrolled in a prospective-two year study at Ain Shams University hospital: 64 patients with RA and 59 patients with other rheumatic diseases as controls. RA patients were fulfilling the traditional and the new ACR/EULAR diagnostic criteria for RA. They have been followed up for two years. At baseline, all RA patients were subjected to: Clinical assessment of disease activity by taking full histories, general and local examination, measurement of 28 joint count of tender and swollen joints with calculation of disease activity score (DAS-28 for each patient. Complete blood count, erythrocytes sedimentation rate, C-reactive protein and rheumatoid factor titers were performed. Anti-MCV IgG immunoglobulins' assay was performed at the study endpoint by ELISA. RA patients were then classified into; anti-MCV positive and anti-MCV negative groups for statistical comparison. Plain X-ray was performed on the peripheral joints and scored by the Simple Erosion Narrowing score (SEN-score. Magnetic Resonance Imaging (MRI scans were carried out to 22 RA patients on cervical and lumbosacral regions. Results: Anti-MCV antibodies were found to be of high sensitivity (79.6% and specificity (96.6% in diagnosing RA. The area under the curve was 0.893 at 95% confidence interval (CI, confers an odds ratio of 23.5. Anti-MCV positive RA patients had significantly higher DAS-28 and SEN-scores than anti-MCV negative patients; who were found to have more benign disease with lower incidence of
Compression response of tri-axially braided textile composites
Song, Shunjun
This thesis is concerned with characterizing the compression stiffness and compression strength of 2D tri-axially braided textile composites (2DTBC). Two types of 2DTBC are considered differing only on the resin type, while the textile fiber architecture is kept the same with bias tows at 45 degrees to the axial tows. Experimental, analytical and computational methods are described based on the results generated in this study. Since these composites are manufactured using resin transfer molding, the intended and as manufactured composite samples differ in their microstructure due to consolidation and thermal history effects in the manufacturing cycle. These imperfections are measured and the effect of these imperfections on the compression stiffness and strength are characterized. Since the matrix is a polymer material, the nonuniform thermal history undergone by the polymer at manufacturing (within the composite and in the presence of fibers) renders its properties to be non-homogenous. The effects of these non-homogeneities are captured through the definition of an equivalent in-situ matrix material. A method to characterize the mechanical properties of the in-situ matrix is also described. Fiber tow buckling, fiber tow kinking and matrix microcracking are all observed in the experiments. These failure mechanisms are captured through a computational model that uses the finite element (FE) technique to discretize the structure. The FE equations are solved using the commercial software ABAQUS version 6.5. The fiber tows are modeled as transversely isotropic elastic-plastic solids and the matrix is modeled as an isotropic elastic-plastic solid with and without microcracking damage. Because the 2DTBC is periodic, the question of how many repeat units are necessary to model the compression stiffness and strength are examined. Based on the computational results, the correct representative unit cell for this class of materials is identified. The computational models and
Experimental Investigation of Inlet Distortion in a Multistage Axial Compressor
Rusu, Razvan
The primary objective of this research is to present results and methodologies used to study total pressure inlet distortion in a multi-stage axial compressor environment. The study was performed at the Purdue 3-Stage Axial Compressor Facility (P3S) which models the final three stages of a production turbofan engine's high-pressure compressor (HPC). The goal of this study was twofold; first, to design, implement, and validate a circumferentially traversable total pressure inlet distortion generation system, and second, to demonstrate data acquisition methods to characterize the inter-stage total pressure flow fields to study the propagation and attenuation of a one-per-rev total pressure distortion. The datasets acquired for this study are intended to support the development and validation of novel computational tools and flow physics models for turbomachinery flow analysis. Total pressure inlet distortion was generated using a series of low-porosity wire gauze screens placed upstream of the compressor in the inlet duct. The screens are mounted to a rotatable duct section that can be precisely controlled. The P3S compressor features fixed instrumentation stations located at the aerodynamic interface plane (AIP) and downstream and upstream of each vane row. Furthermore, the compressor features individually indexable stator vanes which can be traverse by up to two vane passages. Using a series of coordinated distortion and vane traverses, the total pressure flow field at the AIP and subsequent inter-stage stations was characterized with a high circumferential resolution. The uniformity of the honeycomb carrier was demonstrated by characterizing the flow field at the AIP while no distortion screens where installed. Next, the distortion screen used for this study was selected following three iterations of porosity reduction. The selected screen consisted of a series of layered screens with a 100% radial extent and a 120° circumferential extent. A detailed total
Structure of the Anayet Permian basin (Axial Zone, Central Pyrenees)
Rodriguez, L.; Cuevas, J.; Tubía, J. M.
The Anayet Permian basin was generated by strike-slip tectonics that opened subsident basins with pull-apart geometries in the western Spanish Axial Zone (between the Aragon and Tena valleys). A continental succession of Permian age, that represents the first post-variscan deposits in the area, fills the basin and covers discordantly Devonian to Carboniferous limestones, sandstones and slates. Permian deposits have been classically divided in four main detrital groups, with three basic volcanic episodes interbedded (Gisbert, 1984, Bixel, 1987): the Grey Unit (50-120 m, Estefanian to Kungurian) with slates, conglomerates, tobaceous slates, coal and pyroclastic deposits, the Transition Unit (50 m maximum) showing grey and red sandstones and lutites with oolitic limestones intercalated, the Lower Red Unit (250 m) composed of cross-bedded red sandstones and andesitic volcanic rocks at the top, and finally the Upper Red Unit (400 m minimum, top eroded) formed by three fining up megasequences of carbonates, red sandstones and lutites with lacustrine carbonates intercalated and alkali basalts at the top. Increasingly older rocks are found towards the western part of the basin, where its depocenter is located. South-vergent angular folds deform the Permian sedimentary succession. Fold axes are N115 °E-trending, almost horizontal and are characterized by a remarkably constant orientation. Folds exhibit a long limb dipping slightly to the north and a short vertical limb, occasionally reversed. In the Anayet basin four main folds, with a wavelength of 400 m, can be distinguished, two anticlines and two synclines, with minor folds associated. Related to the angular folds an axial plane foliation, E-trending and dipping 40 to 60° to the north, is developed in the lutites. The more competent rocks, conglomerates and breccias, only locally show a spaced fracture cleavage. No main thrusts have been detected in Permian rocks. However, minor scale decollements, usually low angle