text:
... Jointly organized with Indian Statistical Institute, Kolkata,
and Department of Statistics & Applied Probability, NUS
(as of 16 Jul 2009)
The Q-tensor theory of liquid crystalsJohn Ball, University of Oxford, UKThe lectures will survey what is known about the mathematics of the de Gennes Q-tensor theory for describing nematic liquid crystals. This theory, despite its popularity with physicists, has been little studied by mathematicians and poses many interesting questions. In particular the lectures will describe the relation of the theory to other theories of liquid crystals, specifically those of Oseen-Frank and Onsager/Maier-Saupe.
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The second-order multi-scale simulation for the physics and mechanics behaviors of composites and their structuresJunzhi Cui, Chinese Academy of Sciences, China
Diffuse interface modeling and simulation of some interface problemsQiang Du, Pennsylvania State University, USAThe diffuse interface (or phase field) method has been one of the popular approaches for the modeling and simulation of many interface problems in nature. In this series of lectures, we first present some of the basic ideas of the diffuse interface approach. Examples are shown to illustrate its effectiveness in practice. Next, we discuss the relevant mathematical theory, consider the sharp interface limit and make comparisons with other methods. We then focus on some recent works related to the application of the diffuse interface method to interface problems in materials science and biology, in particular, those problems involving elastic energy contributions. These specific applications are used to highlight the modeling and computational challenges. We also discuss a stochastic implicit interface method for modeling the effect of fluctuations in interfacial problems. Finally, we report some recent progress in the algorithmic development aspect. The lectures will be of introductory nature, with emphasis on the basic methodology, the important issues and some open problems.
Predictive atomistic and coarse-grained modeling of epitaxial thin film growthJim Evans, Iowa State University, USAAtomistic modeling of homoepitaxial film growth on single-element single-crystal surfaces (A on A), when combined with kinetic Monte Carlo (KMC) simulation, has achieved remarkable predictive accuracy for some systems [1]. This applies not just for the description of initial submonolayer 2D island formation, but also for subsequent multilayer growth and kinetic roughening (including formation of 3D mounds, i.e., multilayer stacks of 2D islands). However, coarse-grained modeling alternatives are appealing from the perspective of algorithmic efficiency, and also to provide deeper insight into fundamental issues such as development 2D island distributions or 3D mound coarsening dynamics. We review the current state of this field [1]. Our recent efforts have begun to explore more complex deposition processes on binary alloy surfaces (e.g., A on BC, B+C on BC) [2] and on ternary quasicrystal surfaces (A on BCD) [3].
For the former, predictive atomistic modeling has been achieved, and for the latter coarse-grained step-dynamics modeling has provided significant insight.
Of particular interest here is height-selection of multilayer islands due to quantum size effects.
[1] J.W. Evans, P.A. Thiel, and M.C. Bartelt, Surf. Sci. Rep. 61 (2006) 1-128.
[2] Han, Liu, Unal, Qin, Jing, Jenks, Thiel, Evans, Phys. Rev. Lett. 100
(2008) 116105.
[3] Unal, Fournee, Thiel, Evans, Phys. Rev. Lett. 102 (2009) 196103.
Coarsening of island distributions on surfaces: Ostwald vs Smoluchowski vs unconventional ripening pathwaysJim Evans, Iowa State University, USAPost-deposition evolution of distributions of 2D islands in pristine homoepitaxial systems provides an ideal testing ground for coarsening theories. Traditionally, Ostwald ripening (OR), i.e., dissolution of small islands and growth of larger ones, is expected to provide the dominant coarsening pathway.
Indeed, OR is often observed revealing behavior consistent with well-developed LSW theory. However, sometimes coarsening is dominated by Smoluchowski ripening (SR), i.e., diffusion and coalescence of islands. Here, typically detailed behavior deviates from predictions of classic rate equation predictions. We both elucidate the features controlling the dominant pathway and origin of the deviations from classic predictions [1]. Introducing even trace-amounts of a chemical additive often greatly accelerates the coarsening process [1,2].
We provide two possible mechanisms, either additive-catalyzed coarsening for attachment-detachment limited OR, or enhanced mass transport due to facile formation of a mobile metal-additive complex.
[1] Thiel, Shen, Liu, Evans, J. Phys. Chem. C 113 (2009) 5047 (Centennial Feature) [2] Shen, Liu, Thiel, Evans, J. Chem. Phys. 130 (2009) 094701
Computational surface partial differential equationsCharles Elliott, University of Warwick, UKEvolutionary PDEs on stationary and moving surfaces appear in many applications such as the diffusion of surfactants on fluid interfaces, surface pattern formation on growing domains, segmentation on curved surfaces and phase separation on biomembranes and dissolving alloy surfaces.
In this talk I discuss three numerical approaches based on:- (I) Surface Finite Elements and Triangulated Surfaces, (II)Level Set Method and Implicit Surface PDEs and (III) Phase Field Approaches and Diffuse Surfaces.
Toward quantitative analysis of nanoelectronics --- state of the art and challengesHong Guo, McGill University, CanadaNanoelectronic devices operate by principles of quantum mechanics, their properties are closely influenced by the atomic and molecular structures of the device. It has been a challenge to calculate device characteristics including relevant microscopic details, especially when one wishes to predict these characteristics without relying on phenomenological parameters.
In this lecture, I will review the present status of nanoelectronic device theory, the existing theoretical and numerical difficulties, and some important problems of nanoelectronics. I will then discuss in detail a particularly useful progress achieved toward quantitative predictions of non-equilibrium and non-linear charge/spin quantum transport in nanoelectronic devices from atomic point of view. The theoretical formalism is based on carrying out real space density functional theory (DFT) analysis within the Keldysh nonequilibrium Green's function (NEGF) framework [1,2]. The theoretical background as well as numerical implementation of the NEGF-DFT formalism will be presented [1,2,3]. Quantitative comparisons to measured data will be presented. I will give many examples of calculating quantum transport in nanostructures starting from atomic arrangements of the device, including molecular wires, carbon nanostructures, magnetic tunnel junctions, disordered systems, and various spintronic systems. I will end the lecture by outlining a view on the existing challenges of nanoelectronics, and on developing tools powerful enough for nanoelectronics design automation.
I plan to cover the following technical issues in this 6-hour lecture:
(1) Quantum transport theory within NEGF. After a brief technical discussion on how to derive transport formula using NEGF, I will discuss a symbolic derivation software we have developed recently using Mathematica, that automatically derives relevant NEGF and transport formula starting from the Hamiltonian.
(2) Computational method of NEGF-DFT [1,2,3]. I will focus on important technical issues about how this formalism works and what are the important things to take care of in order to do a correct simulation. Other issues such as electron-phonon scattering during current flow, strong correlation effects in tunnelling through oxides, will also be discussed.
(3) Computational method of NEGF-DFT-NVC [4]. I will discuss how to carry out nonequilibrium vertex correction (NVC) analysis of disorder scattering in nanoelectronic devices. Since any real system has some degree of disorder, configurational average of transport properties must be done. NVC allows one
to accomplish this very important task from first principles.
Acknowledgements. The work presented here were contributed by many students and postdocs over many years: Drs. Jian Wang, Jeremy Taylor, Jose-Luis Mozos, Hatem Mehrez, Brian Larade, Gianni Taraschi, Qingrong Zheng, Wengang Lu, Eric Zhu, Lei Liu, Chaocheng Kaun, Pawel Pomorski, Yi Liu, Dan Robutsov, Nicolai Sergueev, Derek Waldron, Devrim Guclu, Vladimir Timochevski, and Chuncheng Wan. I'd like to also thank the following group members who contributed to the topics of this lecture: Dr. Yibin Hu, Dr. Wei Ji, Dr. Ferdows Zahid, Mr. Zimin Feng, Zhanyu Ning, Tao Ji, Manuel Smeu, Jesse Masson, Etienne Marcotte.
Some References:
[1] "Ab initio modelling of quantum transport properties of molecular electronic devices", Jeremy Taylor, Hong Guo, and Jian Wang, Phys. Rev. B 63, 245407 (2001).
[2] "Ab initio modelling of open systems: charge transfer, electron conduction, and molecular switching of a C60 device", Jeremy Taylor, Hong Guo and Jian Wang, Phys. Rev. B 63, R121104 (2001).
[3] "Nonlinear spin-current and magnetoresistance of molecular tunnel junctions", Derek Waldron, Paul Haney, Brian Larade, Allan MacDonald and Hong Guo, Phys. Rev. Lett. 96, 166804 (2006).
[4] "Disorder scattering in magnetic tunnel junctions: theory of nonequilibrium vertex correction", Youqi Ke, Ke Xia and Hong Guo, Phys. Rev. Lett. 100, 166805 (2008).
The mathematical understanding of tau-leaping algorithmTiejun Li, Peking University, ChinaThe tau-leaping algorithm is proposed by D.T. Gillespie in 2001 for accelerating the simulation for chemical reaction systems. It is faster than the traditional stochastic simulation algorithm (SSA), which is an exact simulation algorithm. In this lecture, I will overview some recent mathematical results on tau-leaping done by our group, which include the rigorous analysis, construction of the new algorithm, and the systematic analysis of the error.
Introduction to molecular modelsXiantao Li, Pennsylvania State University, USAI will provide the following lectures
1. Introduction to molecular models
2. Statistical mechanics
3. Simulation technique
Ginzburg-Landau Equations---some recent developments and open problemsFanghua Lin, Courant Institute, USAWe shall first go over briefly some background and earlier work on the Ginzburg-Landau equations. Then we shall describe some recent work concerning generalized Ginzburg-Landau equations including multiple components Ginzburg-Landau equations and their applications.
Topological vorticity and conserved geometric motionFanghua Lin, Courant Institute, USAAfter a quick review of some distinct feature of vortex dynamics in classical fluids, we shall describe a notion of topological vorticity that plays the similar important role as vorticity in the classical fluids. We can use the topological vorticity to study vortex dynamics in ferromagnets and Bose-Einstein condensates for example. Then I shall expalin my recent joint work with Jun-Cheng Wei on Kelvin motions of traveling vorticies solutions and some genral conserved geometric motion.
Some numerical analysis issues in material and fluids simulationsJian-Guo Liu, Duke University, USAMany recently developed computation methods to overcome some challenges in multi-scale material/fluids simulations such as removing stiffness in time stepping due to fast waves, controlling the numerical dissipation with respect to the large parameters in the underline system, effectively local upscaling, etc. Numerical Analysis for these methods are difficulty. In this talk, I will present some results along this direction for a class of asymptotic preserving schemes.
Mathematical models for liquid crystalsDaniel Phillips, Purdue University, USALiquid crystal materials can exist in a variety of phases that exhibit different levels of order. This order melts and defects appear if either their temperature is increased or if external stresses are applied. In this lecture we describe several mathematical models that are used to characterize and study these features.
Efficient and accurate numerical schemes for the phase-field models for multiphase complex fluidsJie Shen, Purdue University, USAI shall start with an introduction on an energetic variational phase field model for multiphase incompressible flows which leads to a set of coupled nonlinear system consisting a phase equation and the Navier-Stokes equations.
Then, I'll present efficient and accurate numerical schemes for solving this coupled nonlinear system. In particular, the following topics will be covered:
1. Splitting methods for unsteady incompressible Navier-Stokes equations
2. Fast spectral-Galerkin methods for elliptic problems
3. Full discretization for the coupled phase-field model
4. Spectral moving meshing method for the coupled phase-field model
Phase-field models for multiphase complex fluids: modeling, numerical analysis and simulationsJie Shen, Purdue University, USAI shall present an energetic variational phase field model for multiphase incompressible flows which leads to a set of coupled nonlinear system consisting a phase equation and the Navier-Stokes equations. We shall pay particular attention to situations with large density ratios as they lead to formidable challenges in both analysis and simulation.
I shall present efficient and accurate numerical schemes for solving this coupled nonlinear system, and show ample numerical results (air bubble rising in water, Newtonian bubble rising in a polymeric fluid, defect motion in a liquid crystal flow, etc.) which not only demonstrate the effectiveness of the numerical schemes, but also validate the flexibility and robustness of the phase-field model.
Grain growth, shape, and topology in all dimensions: beyond von Neumann-MullinsDavid Srolovitz, Princeton University, USA and Yeshiva University, USACellular microstructures are ubiquitous in nature. They can be found in polycrystalline microstructures, foams, plant epidermis, ferroelectrics, complex fluids, and even in ice cream. In many situations, the cell/grain/bubble walls move to reduce their surface area (a surface tension effect), with a velocity proportional to the wall's mean curvature. As a result, the cells evolve and coarsen. Using this relation, and little else, von Neumann gave an exact formula for the growth rate of a cell in a 2-d cellular structure, which is the basis of modern grain growth theory. Borrowing ideas from geometric probability, we present an exact solution for the same problem in 3-d using the "mean width." We then describe why the mean width is the natural linear measure of grain size and topology and is useful across broad swaths of the sciences. Next, we extend this 50 year-old theory into all dimensions. Finally, we discuss using these ideas to efficiently simulate grain growth.
Theory and modeling of reactive eventsEric Vanden-Eijnden, Courant Institute, USAThe dynamics of a wide range of systems involve reactive events, aka activated processes, such as conformation changes of macromolecules, nucleation events during first-order phase transitions, chemical reactions, bistable behavior of genetic switches, or regime changes in climate. The occurrence of these events is related to the presence of dynamical bottlenecks of energetic and/or entropic origin which effectively partition the phase-space of the dynamical system into metastable basins. The system spends most of its time fluctuating within these long-lived metastable states and only rarely makes transitions between them. The reactive events often determine the long-time evolution of the system one is primarily interested in. Unfortunately, computing up to the time scale at which these events occur represent an enormous challenge and so there is an urgent need for developing new numerical tools for such computations.
In the first lecture, I will explain why we may need to go beyond the standard framework of transition state theory (TST) to describe activated processes and reactive events, and I will present another framework, termed transition path theory (TPT), that permits to do that. Unlike TST, which gives mainly an expression for the rate of the reactive event, TPT describes more fully the statistical properties of the reactive trajectories (i.e. those trajectory by which the reactive event occurs), in particular in terms of their probability density function and their probability current.
In the second lecture, I will describe how TPT can be use to design and/or improve numerical methods for computing the pathways and rate of reactive events. I will focus in particular on the string method and milestoning.
Some issues in the long-time simulation of complex systemsEric Vanden-Eijnden, Courant Institute, USAThe dynamics of many systems of interest span many spatio-temporal scales, making their analysis by numerical simulations difficult. Indeed, while we are bound to simulate the dynamics at the smallest and fastest scales, we are often interested in the system's behavior in the largest and slowest scales. These are typically not accessible to brute force simulations, both because of the computational cost involved but also because these time scales are way beyond the time at which we lose pathwise accuracy with standard numerical integrators. These difficulties force us to change perspective and look at the systems from a probabilistic viewpoint. Indeed, besides being unreliable, long time numerical trajectories are also irreproducible due to sensitivity to initial conditions and/or small perturbations, and they are typically uninformative per se. By identifying the right statistical descriptors for the systems that characterize their behavior, like e.g. their invariant measure, the time-correlation functions of suitable observable, or several statistical objects describing rare reactive, we can build algorithms that are tailor-made to calculate these descriptors accurately and efficiently. In this talk this strategy will be elucidated and illustrated on examples arising from material sciences, atmospheric sciences and molecular dynamics.
Boundary treatment, exact Hodge decomposition and the LBB condition for MAC-like schemes on curvilinear domainsWei-Cheng Wang, National Tsing-hua University, TaiwanWe propose a new finite difference scheme for Navier-Stokes equations in primitive formulation on curvilinear domains. With proper boundary treatment and interplay between covariant and contra-variant components, the spatial discretization admits exact Hodge decomposition and energy identity. As a result, the pressure can be decoupled from the momentum equation with explicit time stepping. No artificial pressure boundary condition is needed. In addition, the spatial discretization is shown to satisfy the Ladyzhenskaya-Babuska-Brezzi (LBB) condition, leading to a rigorous error estimate of optimal order for the pressure. Numerical experiment demonstrates the robustness and efficiency of our scheme.
This is a joint work with Yin-Liang Huang and Jian-Guo Liu.
Phase field simulations of two phase fluid flowXiao Ping Wang, Hong Kong University of Science and Technology, Hong KongIn this talk, I will first describe a newly developed phase field model for two phase fluid flow based on Cahn Hilliard Navier Stokes equation with generalized Navier boundary condition. Then some numerical results on two phase flow on rough and patterned surfaces will be presented. Issues related to drop formation, dripping to jetting transition will also be discussed.
A new version fast multipole method for evaluating the stress field of dislocation ensemblesYang Xiang, Hong Kong University of Science and Technology, Hong KongDislocations are the primary carriers of plastic deformation in crystals. Dislocation dynamics simulation is becoming an important tool for the study of plastic behaviors of crystalline materials. A crucial part of dislocation dynamics simulation is the calculation of the stress field of dislocation ensembles due to the long-range interaction of dislocations. We apply a new version of the fast multipole method (FMM) to compute the stress field of dislocation ensembles, in which exponential expansions are introduced to diagonalize the multipole-to-local translations. Numerical experiments show that for a dislocation ensemble discretized into N dislocation segments, the new version of the FMM is asymptotically O(N) with an optimized prefactor, and very efficient for prescribed accuracy requirements.
Homogenization of non-coercive Hamilton-Jacobi equationsJack Xue Xin, University of California, Irvine, USANon-coercive Hamilton-Jacobi equations arise in modeling dynamical behavior of material interfaces in solids and fluids. Properties of homogenized Hamiltonians are compared for periodic and random media, nonlinearities and viscosity effect. Both Lagrangian and Eulerian approaches and examples will be discussed.
On the different phases and dynamical models of liquid crystalPingwen Zhang, Peking University, ChinaThis talk provides a brief review of our basic understanding of liquid crystal phases from both macroscopic and microscopic points of view. From the macroscopic perspective, phases can be identified utilizing a series of thermodynamic properties based on classical thermodynamics; from the microscopic perspective, a phase needs to be defined on the basis of its structural symmetry and the types of order found in the phase. These two different perspectives can be reconciled by using statistical mechanics to bridge the length scale differences.
There are many different liquid crystalline phases that have been identified and characterized, the nematic phase possesses the lowest order with only long range molecular orientational order and short range positional and bond orientational order. The next class of liquid crystalline phases is the smectic phase, which possesses layered structures. In this talk, brief general descriptions are given for the thermodynamics and kinetics of phase transitions.
The Ericksen-Leslie, Tensor and Doi-Onsager kinetic models will be introduced to study the phase and phase transition, the kinetic-hydrodynamic liquid crystalline model will be used to classify the pattern formation of microstructures and the dynamics of defects. The relation of liquid crystalline models, and their limited regions, will be pointed out.
The first-principles electronic structure calculations based on finite element discretizationsAihui Zhou, Chinese Academy of Sciences, ChinaIn this presentation, we will give a brief introduction to first-principles elec-
tronic structure calculations and talk about some recent fnite element compu-
tations in quantum chemistry and materials science. This presentation is based
on the joint works with X. Dai, X. Gong, L. Shen, Z. Yang, and D. Zhang.
Ab initio methods for quantum transport in macro-moleculesStefano Sanvito, Trinity College Dublin, IrelandThe non-equilibrium Green's function (NEGF) method for electron transport combined with density functional theory (DFT) is at present the workhorse of material specific transport calculations. Despite some difficulties connected to the mean-field nature of the semi-local approximations to DFT [1], NEGF-DFT provides a powerful computational tool for research areas as diverse and magneto- and molecular electronics, biological sensing, and in general nano-electronics. Still challenges remain ahead in particular related to the ability of describing strong correlations, inelastic effects and in the make of algorithms scalable to large systems.
In recent years our group has developed the Smeagol code (www.smeagol.tcd.ie), at present probably the most versatile code for quantum transport available worldwide [2,3]. In this talk I will review the main capabilities of Smeagol and in particular I will tackle the problems arising when dealing with large devices. I will then discuss two examples.
First I will consider spin-transport across a Mn12 molecule and demonstrate that orbital re-hybridization determines entirely the features of the I-V characteristics [4]. Interestingly the I-V presents a number of negative differential conductances at various voltages which are the fingerprint of the magnetic state of the molecule. This opens up the possibility of an electrical read-out of the molecular state.
Then I will move my attention to DNA. In particular I will discuss the transport properties of polymeric Poly-C/Poly-G strands connected to gold electrodes. The calculations will shed some light on the intrinsic nature of DNA transport and will tackle, with an effective theory, the effects due to the biological environment.
[1] Self-interaction errors in density functional calculations of electronic transport,
C. Toher, A. Filippetti, S. Sanvito, and Kieron Burke, Phys. Rev. Lett. 95 146402 (2005)
[2] Towards Molecular Spintronics, Alexandre Reily Rocha, Victor Garcia-Suarez, Steve W. Bailey, Colin J. Lambert, Jaime Ferrer and Stefano Sanvito, Nature Materials 4, 335 (2005).
[3] Spin and Molecular Electronics in Atomically-Generated Orbital Landscapes, Alexandre Reily Rocha, Victor Garcia-Suarez, Steve W. Bailey, Colin J. Lambert, Jaime Ferrer and Stefano Sanvito, Phys. Rev. B. 73, 085414 (2006).
[4] Magnetic state electrical readout of Mn12 molecules, C.D. Pemmaraju, I. Rungger and S. Sanvito, arXiv:0905.0281 (2009)
Asymptotically correct finite difference schemes for highly oscillatory ODEsAnton Arnold, Vienna University of Technology, AustriaWe are concerned with the numerical integration of ODEs of the form
$\epsilon^2 \psi_{xx} + a(x)\psi=0$ for given $a(x)\ge\alpha>0$ in the highly oscillatory regime $0<\epsilon\ll 1$ (appearing as a stationary Schr\"odinger equation, e.g.). In two steps we derive an accurate finite difference scheme that does not need to resolve each oscillation:
1) With a WKB-ansatz the dominant oscillations are "transformed out", yielding a much smoother ODE.
2) For the resulting oscillatory integrals we devise an asymptotic expansion both in $\eps$ and $h$.
In contrast to existing strategies, the presented method has (even for a large spatial step size $h$) the same weak limit (in the classical limit $\epsilon\to 0$) as the continuous solution. Moreover, it has an error bound of the order $O(\epsilon^2 h^2)$.
Ref: A. ARNOLD, N. BEN ABDALLAH and C. NEGULESCU: WKB-based schemes for the Schr\"odinger equation in the semi-classical limit, preprint 2009.
Analysis and computation for the semiclassical limits of the nonlinear Schrodinger equationsWeizhu Bao, National University of SingaporeIn this talk, I will review recent results on analysis and efficient computation for the semiclassical limits of linear and nonlinear Schrodinger (NLS) equations. First, I will show our recent asymptotic and numerical results on the semiclassical limits of the ground and excited states of time-independent NLS with a few typical external trapping potentials. Then I will review the formal semiclassical limit of the NLS by using different approaches including WKB method, Winger transform, Grenier's
generalized WKB analysis, etc. A time-splitting spectral (TSSP) method was introduced to efficiently compute the dynamics of the NLS in the semiclassical regimes. The numerical method is explicit, unconditionally stable, time reversible and time transverse invariant. Moreover, it conserves the position density in the discretized level and has the best spatial/temporal resolution for the NLS in the semiclassical regimes. Comparison between the solutions of the NLS and its quantum hydrodynamical limit are presented, especially when the quantum hydrodynamical equations have shocks and/or vacuum. Finally, the analysis and
computation results are extended for the NLS with an angular momentum rotation term and coupled nonlinear Schrodinger equations.
Introduction to dislocation dynamicsYongwei Zhang, National University of Singapore and Institute of High Performance ComputingDislocations are an important class of defects in crystalline solids. Therefore, the subject of dislocations is essential for an understanding of many of the physical and mechanical properties of crystalline solids. We first show experimental observation of dislocations, and then discuss physical basis for dislocations and some elementary geometric properties of dislocations. We then discuss elastic properties and movement of dislocations. Under most dynamic conditions, dislocations move so slowly that the dynamic displacements are approximated quite accurately by these static solutions. However, when dislocation moving velocity is close to the speeds of sound, the dynamic effect may become important. We will discuss displacement and stress fields of the moving screw dislocations and the moving edge dislocations, dislocation acceleration and radiation, supersonic dislocations and dislocation mobility. It should be noted that many of the theories developed for specific experiments are still tentative. The theory of dislocations presented here is in quite a general approach.
Modelling the heteroepitaxial growth of novel surface nanostructuresYongwei Zhang, National University of Singapore and Institute of High Performance ComputingSurface roughening of a mismatched thin film leads to the formation of three-dimensional islands, or quantum dots. This roughening is via surface diffusion driven by strain energy relaxation. This spontaneous roughening process was proposed to grow uniform and regular quantum dot arrays since uniform and regular quantum dot arrays with precisely controlled positions and sizes are desired for making the template for the next generation of nanoelectronic devices. However, numerical experimental results have shown that unguided self-assembled growth of quantum dots usually fails to realize perfectly ordered dot arrays. Hence how to reliably and reproducibly achieve ordered quantum dot arrays through surface pre-patterning is an interesting topic.
In the present work, three-dimensional finite element method was developed to investigate the self-assembly of heteroepitaxial quantum structures during Stranski-Krastonov growth. In the model, various factors such as strain energy, surface energy, wetting effect, surface energy anisotropy and elastic anisotropy, and substrate surface pre-patterning were taken into account, and the SiGe/Si material system was used as a model system. We consider quantum structures growing on both flat substrate surfaces without patterns or with patterns. Our computer simulations showed that various quantum dot surface patterns can be obtained by the guided self-assembled growth, including some novel surface structures such as quantum-dot automata arrays, fortress-enclosed quantum-dot automata arrays, and ordered quantum dot arrays. Parametric studies have been performed to obtain the phase diagrams for obtaining various surface patterns. The present simulation work demonstrates that the coupling of surface pre-patterns, surface energy anisotropy and elastic anisotropy strongly influences the surface roughening morphology, self-assembly and shape transition of epitaxial quantum dots, resulting in diverse evolution pathways.
Design of materials for sustainable manufacturing by computer modelingPing Wu, Institute of High Performance ComputingAlthough Nobel Laureate Steven Chu (currently the 12th United States Secretary of Energy) already developed methods to cool and trap atoms with laser light in late last century, it is still a dream to use them to manufacture very small electronic components. Therefore, it is widely believed that we will hit the Moore's law limit in the years 2015-2020. Furthermore, we may soon face a manufacturing cost explosion based on Moore's second law, which is doubling in cost of chip fabrication plants every four years. New paradigms of sustainable technology are needed to get us around these limits. Computer modeling is capable of exploring these sustainable manufacturing solutions. In my presentation I shall use real-life case studies to outline the design of materials based on affordable computer modeling techniques.
Heat/Phonon transport in nanostructures and PhononicsBaowen Li, National University of SingaporeIn the first part, I will focus on several fundamental issues such as whether heat conduction in nanostructures obeys the Fourier law, how heat pulse spreads in low dimensional nanostuctures, how to reduce thermal conductivity of nanowires and nanotubes. Both computational simulation and experimental results will be presented.
In the second part, I will discuss how to build different thermal devices such as thermal rectifier/diode, thermal transistor, thermal logic gate and thermal memory.
Numerical simulation of coupled surface and grain boundary motionZhenguo Pan, National University of SingaporeA coupled surface and grain boundary motion which arises in materials science is considered in a bicrystal in the context of the quarter loop geometry. Two types of normal curve velocities are involved: motion by mean curvature and motion by surface diffusion. Three curves meet at a single point with junction conditions applied. A formulation that describes the coupled normal motion of the curves and preserves arc length parametrization up to scaling is proposed. Numerical convergence and the numerical stability of the existing travelling waves will be shown.
Molecular self-assembly on surfaces and surface nanotemplatesWei Chen, National University of SingaporeCreation of well-ordered functional molecular arrays at the nanometer scale is one of the key issues in the development for future molecular- or nano-electronic devices, solid-state quantum computation, single-electron devices, and biosensors. Molecular self-assembly on surfaces or surface nanotemplates via selective and directional covalent or non-covalent interactions offers a promising bottom-up approach to fabricating molecular nanostructure arrays with desired functionalities over macroscopic areas.
Here, we demonstrate the formation of various well ordered C60 superstructures with tunable periodicity and symmetry using different molecular surface nanotemplates. It is found that that the formation of the tunable C60 molecular arrays arises from the delicate balance between the homointermolecular (van-der-Waals forces), hetero-intermolecular (charge transfer) and molecule-substrate interfacial interactions under different experimental conditions, which can be simply adjusted by choosing appropriate C60 and 6T, 6P or pentacene coverage and post annealing temperature. we also demonstrated a novel bottom-up approach to fabricate self-assembled 2D binary molecular networks on graphite, whose structural stability is sustained through the formation of multiple intermolecular C-F ... H-C hydrogen bonds between the electronegative periphery F atoms of F16CuPc and the electropositive periphery H atoms of 6P, pentacene or DIP. The supramolecular packing structures can be controlled by careful selection of molecular building blocks with appropriate geometry (size and shape) and molecular ratios. Our results suggest that self-assembling of molecular superstructures on surface nanotemplates represents a simple and effective method for the construction of highly ordered functional molecular nanostructure arrays, and offers a versatile route towards the fabrication of novel molecular interconnects and devices.
Binding and patterning of organic molecules on silicon surfacesGuo Qin Xu, National University of SingaporeAttaching functional organic layers to silicon surfaces is emerging as one of the promising approaches in the development of new semiconductor-based microelectronic devices and biosensors. It provides opportunities for incorporating molecular recognition, chirality, chemical/biological sensing, light emission/detection and lubrication for various technological needs. Recent systematic investigations on chemical reactions of organic molecules on silicon surfaces clearly demonstrated that both Si(100) and Si(111)-7x7 can act as reagent-like substrates with a high reactivity for covalent binding of different classes of organic functionalities. Reaction mechanisms including [2+2]-cycloaddition, [4+2]-cycloaddition, dative-bonding, dissociation and ene-like reactions have been revealed and will be discussed, providing a molecule-level understanding on reaction mechanisms, chemical and surface-site selectivities at organic/silicon hybrid interfaces. In addition, new approaches for fabricating organic nanopatterns using self-assembled templates on silicon surfaces will be introduced, which can be useful in growing organic nanomaterials for developing nano- or molecular-scale devices.
Multi-paradigm simulations at the nanoscale: methodology and applications to functional nano materialsHaibin Su, Nanyang Technological UniversityMultiparadigm methods to span the scales from quantum mechanics to practical issues of functional nanoassembly and nanofabrication are enabling first principles predictions to guide and complement the experimental developments by designing and optimizing computationally the materials compositions and structures to assemble nanoscale systems with the requisite properties. In this talk, we employ multi-paradigm approaches to investigate functional nano materials with versatile character, including fullerene, carbon nanotube (CNT), graphene, and related hybrid structures, which have already created an enormous impact on next generation nano devices. The topics will cover the reaction dynamics of C60 dimerization and the more challenging complex tubular fullerene formation process in the peapod structures; the computational design of a new generation of peapod nano-oscillators, the predicted magnetic state in NanoBuds; and opto-electronic properties of graphene nanoribbons.
Topics in surface and nanoscale scienceAndrew Wee, National University of SingaporeIn this talk, I will present some recent work from our NUS surface science group in the areas of graphene and molecular electronics. Graphene research has been proceeding at a relentless pace since it was first isolated in 2004. It is the thinnest known material in the universe and the strongest ever measured. Graphene can sustain huge current densities, and displays record thermal conductivity and stiffness. Electron transport in graphene is described by a Dirac-like equation, which allows the investigation of relativistic quantum phenomena in a benchtop experiment. However, many materials challenges to producing large area high quality graphene still remain. I will discuss our work using in situ STM, synchrotron photoemission (PES) and density functional theory (DFT) calculations to investigate the structure and growth of epitaxial graphene on 6H-SiC(0001).
In the field of organic and molecular electronics, the key issue is the understanding of molecule-metal and organic-organic interfaces. We used STM and synchrotron techniques to study self-assembled molecular arrays and organic heterojunctions. Some ongoing work and future perspectives will also be discussed.
Metallic glasses: It's all in the mixYi Li, National University of SingaporeMaterials such as glass or polystyrene are often called amorphous solids - literally ?without shape? - because their atoms are arranged randomly without the long-range repeating patterns seen in crystals. Scientists have also managed to make amorphous metal alloys known as metallic glasses, which promise great strength, elasticity and magnetic properties. But unlike the well-defined long-range order in the crystalline metals, the atomic arrangements in amorphous alloys remain mysterious at present and the details of how the atoms are packed in amorphous metals are generally far less understood than for the network-forming glasses. In this talk, I shall summarize the recent attempts made at the understanding of the atomic structure in metallic glasses and how one of our recent works gives new insight into this.
Quantum thermal transport from classical molecular dynamicsJian-Sheng Wang, National University of SingaporeTraditional molecular dynamics, since it is based on classical mechanics, produces only classical results. It is possible to simulate quantum thermal and electronic transport using a form of molecular dynamics subject to Langevin heat baths with correlated noises. The noise spectra and the memory kernel are derived by analyzing the effect of the leads of a junction system quantum-mechanically. It is shown that quantum ballistic transport can be reproduced for linear systems, and nonlinear effect can be understood as a quasi-classical approximation to the quantum problems. Results of thermal conductance for one-dimensional lattice chain model, graphene nano-ribbons, and nanotubes will be reported.
Refs. J.-S. Wang, Phys. Rev. Lett. 99, 160601 (2007); J. T. Lü and J.-S. Wang, J. Phys.: Condens. Matter, 21, 025503 (2009).
Brillouin light scattering from nanostructuresZhikui Wang, National University of SingaporeBrillouin light scattering (BLS) is a non-destructive and non-contacting technique for investigating spin and acoustic dynamics, by detecting the inelastic scattered light by the spin waves (magnons) and elastic waves (phonons) in nanostructures. The observation of well-resolved Brillouin peaks arisen from eigenvibrations of nanospheres verified Lamb?s century old theory on eigenvibrations of elastic spheres. Quantization of bulk spin waves in nanowires and bandgap of spin waves in magnonic crystals (magnetic counterpart of semiconductors, photonic crystals or phononic crystals) were first observed using BLS. Experimental data obtained provide information such as quantization of spin and acoustic waves in nanostructures, as well as their magnetic and elastic properties. We found that the magnon frequency bandgaps could be tuned by applying an external magnetic field or by varying their structure dimensions. These findings are expected to stimulate further development of the theory and applications of magnonics.
Microscopic origins of continuum balances and peridynamicsRichard B. Lehoucq, Sandia National Labs, USAPeridynamics (Silling 2000) is a continuum theory where the internal force density in the balance of linear momentum is given by an integral operator. This operator sums internal forces separated by a finite distance in contrast to a continuum theory where only contact forces are assumed. My presentation derives mass and momentum conservation laws for peridynamics using the principles of statistical mechanics. In particular, I show that the peridynamic force density integral operator is the phase space expected value of internal force density given by a general multibody interatomic potential. The derivations generalize the seminal work of Irving-Kirkwood (1950), and build upon the elegant ideas due to Noll (1955) that generalized the former work. The approach presented avoids the standard limitation of a pairwise interatomic potential, and the peridynamic integral operator sidesteps the significant issues associated with determining a stress tensor given a multibody interatomic potential. However, a Cauchy (symmetric) stress tensor is derived so that the divergence of this stress tensor is equal to the peridynamic force density integral operator. This represents a significant generalization of previous definitions of microscopic stress to arbitrary multibody potentials. I also discuss how the integral operator can be replaced by a force density arising from the classical notion of contact forces. Hence, the path from Newton's second law to conservation of linear momentum for simple nonpolar materials traverses peridynamics. This is joint work with Mark Sears.
Dynamic transition theory and equilibrium phase transitionsShouhong Wang, Indiana University, USAIn this talk, I shall present a brief overview of the dynamic transition theory developed recently by Ma and myself, and its applications to equilibrium phase transitions. The main philosophy of the theory is to search for the full set of transition states, giving a complete characterization on stability and transition. The set of transition states --physical "reality"-- is represented by a local attractor. Following this philosophy, the dynamic transition theory is developed to identify the transition states and to classify them both dynamically and physically.
The theory has a wide range of applications in both equilibrium and nonequilibrium phase transitions. The application of the theory to equilibrium phase transitions involves a combination of modeling, mathematical analysis and physical predictions. We adopt the general idea of the Ginzburg-Landau phenomenological approach, and introduce a unified time-dependent Ginzburg-Landau model, based on the le Ch\^atlier principle. Applications to non-equilibrium transitions include typical problems in classical and geophysical fluid dynamics, in climate dynamics, and in chemical reactions. The modeling and the analysis of these problems, on the one hand, provide verifications of existing experimental and theoretical studies, and, on the other hand, lead to various new physical predictions.
To demonstrate the wide range of applications of the theory, I shall present two examples: one is the phase separation of binary systems modeled by the Cahn-Hilliard equation, and the other is superfluidity of liquid helium-3. In both cases, the study leads to some specific physical predictions, which are otherwise unknown from both the physical and mathematical points of view. For example, as a physical prediction, we derive the existence of a new superfluid phase C for liquid helium-3.
Massively parallel algorithms for the simulation of complex flowsUlrich Ruede, University Erlangen-Nuremberg, GermanyLarge scale numerical simulation requires that we exploit parallelism on all levels. High performance computers will continue to be built as parallel systems with physically distributed memory, but each node will be have processors, each of which contains many cores. Additionally each core may rely on vectorization. Such systems can provide enormous compute power, but they may require a special programming and a new design of the algorithms.
The multigrid finite element solvers HHG developed at Erlangen have been run on up to tenthousand processor cores, solving systems with three hundred billion unknowns. As a second example, the talk will report on the Walberla software framework that is being developed for parallel computational fluid dynamics using on the Lattice Boltzmann method and which is being used to study multiphase flows in complex geometries and particulate flows with fully resolved fluid-structure-interaction.
Existence of globally weak solutions to the flow of compressible liquid crystals systemXian-Gao Liu, Fudan University, ChinaWe study a simplified system for the compressible fluid of Nematic Liquid Crystals in a bounded domain in three Euclidean space and prove the global existence of the finite energy weak solutions.
Tailored finite point method for high frequency waves in heterogeneous mediumZhongyi Huang, Tsinghua University, ChinaIn this talk, we propose a tailored-finite-point method for the numerical simulation of the Helmholtz equation with high wave numbers in heterogeneous medium. Our finite point method has been tailored to some particular properties of the problem, then we can get the approximate solutions with the same behaviors as that of the exact solution very naturally. Especially, when the coefficients are piecewise constants, we can get the exact solution with only one point in each subdomain. Our finite-point
method has uniformly convergent rate with respect to wave number $k$ in $L^2$-norm.
A level-set method for self-organized pattern formation during heteroepitaxial growthChristian Ratsch, University of California, Los Angeles, USAIt is well know that strain leads to the formation and self organization of nanostructures and quantum dots during heteroepitaxial growth.
However, modeling these phenomena is a challenging task, because of the vastly different time and length scales involved, and the fact that elastic calculations are computationally expensive due to their long range. In this talk, we will discuss a model for heteroepitaxial growth that employs an island dynamics model with the level-set technique in combination with a fully self-consistent elastic model. Adatoms are described in a mean-field approach, and we solve a diffusion equation for the adatom concentration. At every timestep in the simulation, we solve the elastic equations for the entire system. At every lattice site strain then changes the local bonding, and thus the potential energy surface for adatoms and the microscopic parameters of the simulation, such as adatom diffusion, and the rate of detachment from island edges.We will then present results for several growth phenomena: In the submonolayer regime, islands become smaller and more regular upon increasing strain, and the island size distribution narrows and sharpens. We will discuss how a spatially varying potential energy surface can be exploited for pattern formation.
Such spatial variations are for example a result of defects or other features that are buried under the substrate. Another example is the growth of stacked quantum dots, where islands self-align on top of previously grown islands.
Gate controlled non-volatile graphene ferroelectric memory and spin injection into graphene via MgO barriersBarbaros Oezyilmaz, National University of SingaporeThe discovery of graphene in 2004 has triggered enormous experimental and theoretical efforts. As a gapless semiconductor, charge carriers in graphene can be tuned continuously from electrons to holes crossing the charge neutral Dirac point using an external electric field. Unlike conventional semiconductors, the doping process does not influence the mobility of charge carriers in graphene, which can exceed 10+5 cm+2/Vs-1 at low temperature. Such doping-independent mobility leads to the field-dependent conductance in graphene. Based on these two properties, many novel graphene-based device applications have been predicted. However, a paradigm shift in the microelectronics industry from Si to graphene also requires graphene-based memory applications. Despite graphene having intrinsically a high resistance state at the Dirac point and a low resistance state when heavily doped, reports on graphene for non-volatile information storage is rarely seen. This is due to the difficulty in maintaining the resistance states in graphene without an external electric field.
I will show non-volatile switching in graphene by using ferroelectric gating without having to break the lattice symmetry. We demonstrate basic writing and reading processes of a novel graphene-ferroelectric memory device structure combining the field dependent conductance of graphene with the remnant electric field of ferroelectric thin films. A bistable state of high and low resistance value is realized by controlling the electrical doping level in graphene hysteretically, which is caused by a hysteretic switching of the polarization in the ferroelectric thin-film. Our approach of ferroelectric gating also open up the possibility of studying graphene phenomena in the limit of high carrier concentration, which is not possible with dielectric gating.
I will also report on our resent results on spin transport in graphene observed in the non-local device geometry. Here we have used MBE grown MgO as a tunneling barrier.
Fluid-particle interaction models: asymptotics, theory and numericsJosé A. Carrillo, University Autonoma Barcerona, SpainWe are interested in coupled microscopic/macroscopic models describing the
evolution of particles dispersed in a fluid. Fluid-particle interaction is
of primarily importance in sedimentation analysis of disperse suspensions
of particles in fluids, one of the issues being the separation of the solid
grains from the fluid by external forces: gravity settling processes or
centrifugal forces. On the other hand, aerosols and sprays can be also
modelled by fluid-particle type interactions in which bubbles of suspended
substances are seen as solid particles.
The system is modelled using a Vlasov-Fokker-Planck equation to describe
the microscopic motion of the particles coupled to the Euler equations for
a compressible fluid. We investigate dissipative quantities, equilibria
and their stability properties and the role of external forces. We also study
some asymptotic problems, their equilibria and stability and the
derivation of macroscopic two-phase models. Numerical schemes capable of
dealing with the asymptotic limit situations are proposed. Numerical
simulations will be shown.
A deterministic solver for a hybrid quantum-classical transport model in
NanoMOSFETsJosé A. Carrillo, University Autonoma Barcerona, SpainWe model a nanoMOSFET by a mesoscopic, time-dependent, coupled quantum-classical system based on a sub-band decomposition and a simple scattering operator. We first compute the sub-band decomposition and electrostatic force field described by a Schrödinger-Poisson coupled system solved by a Newton-Raphson iteration using the eigenvalue/eigenfunction decomposition. The transport in the classical direction for each sub-band modeled by semiclassical Boltzmann-type equations is solved by conservative semi-lagrangian characteristic-based methods. Numerical results are shown for both the thermodynamical equilibrium and time-dependent simulations in typical nowadays nanoMOSFETs. This is a work in collaboration with N. BenAbdallah, M.J. Caceres and F. Vecil.
Eigenvalue problem of magnetic Schrodinger operatorsXingbin Pan, East China Normal University, ChinaEigenvalue problems of magnetic Schrodinger operator have played important roles in the mathematical theory of superconductivity, liquid crystals and Bose-Einstein condensates. In this talk we shall introduce basic estimates of the lowest eigenvale for large magnetic field, and give some applications of these estimates in the theory of nucleation of superconductivity and surface superconductivity, and in the theory of phase transition of liquid crystals from nematic phase to smectic phase.
Dynamical self-trapping of Bose-Einstein condensates in shallow optical latticesFong Yin Lim, Institute of High Performance ComputingWe study the transport properties of a strongly repulsively interacting BEC through a shallow optical lattice of finite width. The study is carried out via numerically solving the Gross-Pitaevskii equation. Self-trapped states are observed for some sets of parameters, indicated by stopping in the expansion of BEC at certain lattice site.
Such self-trapped states can be explained analytically in terms of nonlinear Bloch waves, approximated by a truncated Bloch function. The results could help us in the design of atom-transporting wire in an atomic circuit, whose properties can be adjusted in a controllable way.
Event-by-event Monte Carlo simulations: Spatial resolution limits of MeV protons & keV electronsChammika N B Udalagama, National University of SingaporeProgress in fabrication, experimentation and manipulation of structures at the micro/nano-meter regimes constantly push the demands made of microscopy and lithography techniques. This has promoted the use of electrons and ions, with their smaller wavelengths, to improve on the diffraction limited visible photons and not so easily focused x-ray photons. But, to what dimensions can the use of electrons and ions be pursued? Which of Nature's characteristics limit their usefulness and spatial resolution? We attempt to gain insight into these fundamental issues via computational studies in the form of Monte Carlo simulations. Our software, DEEP (Deposition of Energy due to Electrons & Protons), unlike most other Monte Carlo particle penetration simulations software adopts an event-by-event simulation formalism as opposed to that of continuous energy loss. This allows us to appreciate the richness of the energy loss process, particularly that of secondary electron or δ-ray production. DEEP incorporates the EPDL97 cross-sections together with the Hansen-Kocbach-Stolterfoht (HKS) δ-ray model for the relevant physics of ion-matter interactions. We will present recent results of the applications of DEEP to polymethylmethacrylate (PMMA) as the target along with results from recent experiments at CIBA, into high spatial resolution imaging of biological cells using MeV protons.
Dynamic density functional theory and approximations to model crystalline materialsAxel Voigt, Technische Universit, Dresden, GermanyThe phase field crystal model is by now widely used in order to predict crystal nucleation and growth. We demonstrate using a finite element discretization the possibilities for various applications. For colloidal solidification with completely overdamped individual particle motion, we show that the phase field crystal dynamics can be derived from the microscopic Smoluchowski equation via dynamical density functional theory. The different underlying approximations are discussed. We test the validity of the phase field crystal model against dynamical density functional theory. In particular, the velocities of a linear crystal front from the undercooled melt are compared as a function of the undercooling for a two-dimensional colloidal suspension of parallel dipoles. As a second application we use the phase field crystal model to compute anisotropies of surface free energies of nanocrystals as a function of temperature. The approach allows to extract anisotropy functions with cusps. Furthermore we consider liquid phase epitaxy and analyse the transition from step flow growth to step bunching, facetting and formation of dislocations. As a last example we simulate the phase field crystal model on curved surfaces to model spherical crystallography. In particular we are interested in the formation of grain boundary scars on such surfaces.
Good agreement is only obtained by a drastic scaling of the free energies in the phase field crystal model in order to match the bulk freezing transition point.
An adaptive level set method for moving curves and its application to dislocation dynamicsHanquan Wang, Yunnan University of Finance and Economics, ChinaThe original level set equations for motions of curves both in two dimensions and in three dimensions are solved on a uniform mesh, which does not have optimal efficiency in terms of calculations since the region near the curves is of most interest. Later improvement on calculation of level set equations includes narrow-band based local level set techniques and tree-based adaptive level set techniques. Both of them have their advantages and disadvantages.
In this talk, by taking consideration into their advantages, I present an adaptive level set method for motions of curves both in two dimensions and in three dimensions. The method first applies a simple algorithm to generate an adaptive grid which is composed by a fine mesh near the curve and a sparse mesh away from the curve; it next solve the level set equations on the adaptive grid with higher-order numerical methods such as third-order total variation diminishing (TVD) Runge-Kutta method in time and third-order weighted essentially non-oscillatory (WENO) scheme in space. I test this efficient and higher-order numerical method in several numerical examples and apply the method to study dislocation dynamics in material sciences.
This is a joint work with Professor Yang Xiang at Department of Mathematics of the HongKong University of Science and Technology.
Abinitio calculation of entropy and free energy in defected solidsSalvy Russo, RMIT Univeristy, AustraliaCalculating the properties of materials using Density Functional Theory (DFT) has been increasing popular over the last 10-15 years. When predicting the thermodynamic stability of defects (including dopants) in solids using DFT, many studies have only considered the internal energy contribution to the free energy of defect formation.
In this talk we will consider how the various entropic contributions to the formation free energy of a defect can be calculated using DFT (or other levels of theory). These include the configurational, electronic and vibrational contributions to the total entropy of the defect. Various examples ranging from metallic nanoclusters to doped transition metal oxides will be discussed.
POD and CVT based reduced-order modeling for partial differential equationsHyung Chun Lee, Ajou University, KoreaA discussion of reduced-order modeling for partial differential equations is given to provide a context for the construction and application of reduced-order bases. Review of the POD (proper orthogonal decomposition ) and CVT (centroidal Voronoi tessellation) approaches to reduced-order modeling are provided, including descriptions of POD and CVT reduced-order bases, their construction from snapshot sets, and their applications to the low-cost simulations of partial differential equations.
Interfaces, surface energy and solid phase transformationsJohn Ball, University of Oxford, UKPhase transformations in solids lead to interfaces between different variants of the product phase. In some materials these are atomistically sharp, while in others the interface thickness extends over a number of atomic spacings. The talk will discuss different models for describing such interfaces. This is joint work with Elaine Crooks (Swansea) and with Carlos Mora-Corral (Bilbao).
Stable solutions to the Lawrence-Doniach equations in tilted magnetic fieldsPatricia Bauman, Purdue University, USAWe consider minimizers to the Lawrence-Doniach energy for layered uperconductors with nonlinear Josephson coupling. When the exterior magnetic field is nearly parallel to the layers and the Josephson constant is sufficiently small, we show that the global minimizer has no vortices in the layers. We estimate the upper and lower critical magnetic fields in different directions, and identify the pattern of the order parameters in this case.
Sub-linear scaling algorithms for the study of the electronic structure of materialCarlos Garcia-Cervera, University of California, Santa Barbara, USAI will discuss asymptotic-based algorithms for the study of the electronic structure of materials, in the context of density functional theory. I will illustrate the ideas using both the Kohn-Sham and orbital-free formulations.
This is joint work with Weinan E (Princeton University), and Jianfeng Lu (Princeton University).
Modeling nanoelectronics from atomic first principlesHong Guo, McGill University, CanadaIn this talk, I will discuss an aspect of nanoelectronic device theory, namely modeling nanoelectronics from atomic first principles. Some important issues of quantum transport theory in the atomic limit will be reviewed. I will then report a recent theoretical development for treating atomistic disorder in nonlinear and non-equilibrium quantum transport modeling. The theory uses non-equilibrium vertex corrections to handle the configurational average of random disorder at the density matrix level. Using this technique, we have analyzed spin injection in magnetic tunnel junctions with interface roughness as well as with oxygen vacancies in the tunnel barrier. Disorder effect is found to significantly alter spin polarized tunneling. We will also present results concerning surface roughness scattering in Cu interconnects. Comparison with existing experimental data will be presented.
Blow-up criteria for the Navier-Stokes equations of multidimensional compressible fluidsSong Jiang, Institute of Applied Physics and Computational Mathematics, ChinaWe study an initial boundary value problem and the Cauchy problem for the multidimensional Navier-Stokes equations of compressible isentropic and non-isentropic flows. We will report some recent blow-up criteria for the local strong solutions, including a criterion similar to the Beale-Kato-Majda criterion for ideal incompressible flows.
Some recent theoretical and numerical contributions to stochastic homogenization and related problemClaude Le Bris, École Nationale Des Ponts Et Chaussées, FranceThe talk will overview some recent contributions on several theoretical aspects and numerical approaches in stochastic homogenization. In particular, some variants of the theory of classical stochastic homogenization will be introduced. The relation between such homogenization problems and other multiscale problems in materials science will be emphasized. On the numerical front, some approaches will be presented, for acceleration of convergence in stochastic homogenization (representative volume element, variance reduction issues, etc) as well as for approximation of the stochastic problem when the random character is only a perturbation of a deterministic model. The talk is based upon a series of joint works with X. Blanc (CEA, Paris), PL. Lions (College de France, Paris), and F. Legoll, A. Anantharaman, R. Costaouec (ENPC, Paris).
Coarse-graining molecular dynamics for crystalline solidsXiantao Li, Pennsylvania State University, USAI will discuss a coarse-grained model of molecular dynamics in crystalline solids. Such system usually has an underlying lattice structure, and the empirical potentials are of quite simple forms. Thus it provides a nice setting in which coarse-graining (CG) methods can be considered. The goal of the CG method is to reduce the huge
number of atomic degrees of freedom, and arrive at an effective model in which only a small number of atoms are explicitly involved. I will discuss how the CG is done in both the static and dynamic settings, the connections to continuum elasticity models, and the application to fracture and dislocation dynamics.
Surface diffusions on elastically stressed axisymmetric rodsXiao Fan Li, Illinois Institute of Technology, USAMany applications in materials involve surface diffusion of elastically stressed solids. Study of singularity formation and long-time behavior of such solid surfaces requires accurate simulations in both space and time.
Here we present a high-order boundary integral method for an elastically stressed solid with axi-symmetry due to surface diffusions. Using the high-order boundary integral method, we demonstrate that in absence of elasticity the cylinder surface pinches in a finite time at the axis of the symmetry and the universal cone angle of the pinching is found to be consistent with the previous studies based on a self-similar assumption. In the presence of elastic stress, we show that a finite-time, geometrical singularity occurs well before the cylindrical solid collapses onto the axis of symmetry, and the angle of the corner singularity on the cylinder surface is also estimated.
Smectic energies and existence results for lquid crystalsDaniel Phillips, Purdue University, USAWe examine the problem of minimizing the Chen-Lubensky liquid crystal energy. This is a Ginzburg-Landau type energy where the smectic layering is described by a complex valued order parameter. In the case that the energy has a smectic C ground state we show that anchoring conditions on the smectic layering at the boundary are needed in order for minimizers to exist. We further give examples of strong and weak anchoring conditions that suffice.
This is joint work with Patricia Bauman and Jinhae Park.
Long-time asymptotic behaviour of a multiscale rod-like model of polymeric fluidsHui Zhang, Beijing Normal University, ChinaWe investigate the long-time asymptotic behaviour of some multiscale rod-like models for polymeric fluids in various settings which include no flow, shear flow, general bounded domain with homogeneous and non-homogeneous Dirichlet boundary conditions on the velocity. We use entropy approach to obtain the decay rates of dynamic states converging to the equilibrium in some norms by virtue of the Csiszar-Kullback inequality.
A nonlocal vector calculus with application to nonlocal boundary value problemsMax Gunzburger, Florida State University, USAWe develop a calculus for nonlocal operators that mimics Gauss' theorem and the Green's identities of classical vector calculus. The operators we treat do not involve derivatives. We then apply the nonlocal calculus to define variational formulations of nonlocal "boundary" value problems that mimic the Dirichlet and Neumann problems for second-order scalar elliptic partial differential equations. For the nonlocal variational problems, we show how one can derive existence and uniqueness results and also how, under appropriate limits, they reduce to their classical analogs. Although we do not report on this in this talk, the results are easily extended to vector elliptic equations, and in particular, to the peridynamics model for materials.
This is joint work with Richard Lehoucq.
Material prediction based on first principles methodYuan Ping Feng, National University of SingaporeMaterials design based on computational methods is playing a very important role in today?s materials science and engineering. Among various methods, the first-principles electronic structure method based on density functional theory is ideal for designing new materials because such methods do not require experimental inputs and prior knowledge on the materials. We have been using first-principles method to study properties of materials for future advanced technologies and to design new materials. Examples related to high dielectric constant oxides for applications in complementary metal-oxide-semiconductor (CMOS) devices, magnetic semiconductors for spintronics applications, etc., will be discussed.
Applied partial differential equations: the Cambridge PDE groupPeter Markowich, University of Cambridge, UKWe report on the work of the Cambridge based PDE group, covering a wide range of applications, from nonlinear Schrödinger equations to social science modeling
Meissner states of 3-dimensional superconductorsXingbin Pan, East China Normal University, ChinaMeissner state of bulk superconductors of type II loses its stability as the applied magnetic field increases to a critical field H_S. The Meissner states are described by the solutions of a partial differential system in 3-dimensional space, which are called Meissner solutions. In this talk we shall show the existence of the Meissner solutions, and examine the convergence of the Meissner solutions to a solution of the limiting system as the Ginzburg-Landau parameter increases to infinity. Our results suggest that in order to determine the critical field H_S one needs to measure the maximum value of the tangential component of the induced magnetic field on the surface of the superconductor.
Quantum drift-diffusion models in semiconductor simulationLi Chen, Tsinghua University, ChinaAs the dimensions of semiconductor device decrease, quantum effects have to be included in the modeling of the transport phenomena. A brief outline of the quantum fluid dynamic model in semiconductor simulation will be shown in the first part of this talk. Then a list of the mathematical results on one of these models- quantum drift-diffusion model will be introduced, including the existence of global weak solution with different boundary conditions, long time behavior and semiclassical limit. The ideas ?entropy based methods- used in getting those results will be listed in the end.
A generalization of the MacPherson - Srolovitz formulaDuc Thinh Le, Pennsylvania State University, USAThe MacPherson-Srolovitz formula has been recently established as a generalization of the two dimensional von Neumann - Mullins relation for microstructure coarsening. In this talk we present an extension of the MacPherson-Srolovitz formula under more general junction conditions.
Traction and outflow boundary conditions for the incompressible Navier-Stokes equationsJie Liu, National University of SingaporeWe present numerical schemes for the incompressible Navier-Stokes equations (NSE) with open and traction boundary conditions. We use pressure Poisson equation (PPE) formulation and propose new boundary conditions for the pressure on the open or traction boundaries. After replacing the divergence free constraint by this pressure Poisson equation, we obtain an unconstrained NSE. For Stokes equation with open boundary condition on a simple domain, we prove unconditional stability of a first order semi-implicit scheme where the pressure is treated explicitly and hence is decoupled from the computation of velocity. Using either boundary condition, the schemes for the full NSE that treat both convection and pressure terms explicitly work well with various spatial discretizations including spectral collocation and $C^0$ finite elements. Moreover, when Reynolds number is of $O(1)$ and when the first order semi-implicit time stepping is used, time step size of $O(1)$ is allowed in benchmark computations for the full NSE. Besides standard stability and accuracy check, various numerical results including flow over a backward facing step, flow past a cylinder and flow in a bifurcated tube are reported. Numerically we have observed that using PPE formulation enables us to use the velocity/pressure pairs that do not satisfy the standard inf-sup compatibility condition. Our results extend that of H. Johnston and J.-G. Liu (J. Comp. Phys. 199 (1) 2004, 221--259) which deals with no-slip boundary conditions only.
Quantum simulation of materials at micron scales and beyondGang Lu, California State University Northridge, USAWe present a multiscale modeling approach that can simulate multimillion atoms effectively via density functional theory. The method is based on the framework of the quasicontinuum (QC) approach with the density-functional theory (DFT) as its sole energetics formulation - there is no empirical input. The local QC part is formulated by the Cauchy-Born hypothesis with DFT calculations for strain energy and stress. The nonlocal QC part is treated by a DFT-based embedding approach, which couples DFT nonlocal atoms to local region atoms. The method-QCDFT-is applied to a nanoindentation study of an Al thin film, and the results are compared to a conventional QC approach. The results suggest that QCDFT represents a new direction for the quantum simulation of materials at length scales that are relevant to experiments. If time permits, an application of QCDFT to a novel magnetism-induced dislocation motion in NiAl alloys will be also presented.
1. Q. Peng, X. Zhang, L. Hung, E.A. Carter and G. Lu, "Quantum simulation of materials at micron scales and beyond", Phys. Rev. B, 78, 054118 (2008).
2. X. Zhang, C.Y. Wang and G. Lu, "Electronic structure analysis of self-consistent embedding theory for quantum mechanics/molecular mechanics simulations", Phys. Rev. B, 78, 235119 (2008).
3. X. Zhang and G. Lu, "Quantum mechanics/molecular mechanics methodology for metals based on orbital-free density functional theory", Phys. Rev. B, 76, 245111 (2007).
4. G. Lu, E. Tadmor and E. Kaxiras, ?From electrons to finite-elements: a concurrent multiscale approach for metals?, Phys. Rev. B 73, 024108 (2006).
Analysis and computation for the ground states of two-component Bose-Einstein condensates with an external driving fieldYongyong Cai, National University of SingaporeIn this talk, we prove existence and uniqueness results for the ground states of the coupled Gross-Pitaevskii equations for describing two-component Bose-Einstein condensates with an external driving field and obtain the limiting behavior of the ground states with large parameters. Efficient and accurate numerical methods based on continuous normalized gradient flow and gradient flow with discrete normalization are presented for computing the ground states numerically. A modified backward Euler finite difference scheme is proposed to discretize the gradient flows. Numerical results are reported to demonstrate the efficiency and accuracy of the numerical methods and show the rich phenomena of the ground sates in the problem.
Comparisons between the sine-Gordon equation and perturbed nonlinear Schrodinger equations for modeling light bulletsXuanchun Dong, National University of SingaporeComparisons between the solution of the sine-Gordon (SG) equation and the solutions of perturbed nonlinear Schrodinger equations are studied numerically for the propagation of two space dimensional (2D) localized pulses in nonlinear dispersive optical media. We begin with the (2+1) sine-Gordon (SG) equation obtained as an asymptotic reduction in the two level dissipationless Maxwell-Bloch system, followed by the review on the perturbed nonlinear Schrodinger (NLS) equation in 2D for the SG pulse envelopes, which is globally well-posed and has all the relevant higher order terms to regularize the collapse of the standard critical NLS. The perturbed NLS is approximated by truncating the nonlinearity into finite higher order terms undergoing focusing-defocusing cycles.
Energy conservative and efficient semi-implicit Fourier pseudospectral discretizations for the SG and perturbed NLS are proposed. Numerical comparison results between the solutions of the SG and perturbed NLS as well as critical (cubic focusing) NLS are reported for the propa- gation of light bullets. Based on our extensive numerical experiments, the solution of the perturbed NLS as well as its finite terms truncations are in qualitative and quantitative agreement with the solution of SG for the light bullets propagation even after the critical collapse of the cubic focusing NLS. In contrast, the standard critical NLS is in qualitative agreement with SG only before its collapse.


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Thicker hair can make you look more attractive Glossy and thicker hair is what more girls would like to have. Though your hair is short or long, having thick hair just appears to look better. Climate is a major reason why people have various thicknesses of hair. In cold climatic ...Read More »
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The Purpose of A Reunion
My sister created this. She grew the flowers. She arranged the flowers. She photographed it. Then she posted it on Facebook. Her friends gushed in the most heartfelt and genuine compliments, not only about how beautiful it is but all the other beautiful things she has made and the beautiful person she is.
When we were young girls, we sparred over the creative fields we each wanted to enter. When she announced she wanted to be an interior designer when she grew up, I thought to myself, and maybe even said out loud with one of those tones, "I wanted to do that; but now I can't, because she's going to do it."
Today I'm sad to think that through the years of our upbringing (the only time we lived in the same town as each other) I couldn't see that the world was big enough for us to both create beauty from our lives, even if it was doing the same thing.
When I saw this photograph on my Facebook feed I didn't really know her talents, not like her friends did. I wished I could see her in her home—her setting—and see the beauty that radiates from her now.
At the same time, I was researching a place to hold an extended family reunion. I had asked my friend about the place her family used and that began a dialogue about the purpose of a family reunion. I spouted my opinions with confidence, as if I knew what a family reunion should accomplish.
But after I saw my sister's flower arrangement, I formed a more humble opinion. Now, when I go to a reunion, I want to acquaint myself with who my family has become and love each one.
Photo credit: Lara Humble. All rights reserved.
3 Comments
It can be sad that strangers (to us) often know our family members better than we do. Thank goodness for skype, blogs, facebook, twitter…to help us draw closer! But there's nothing like a family reunion!
And, I'm grateful your sister took interior designing so that you could develop your creativity as a writer!
lovely flowers. She is very talented. As are you.
My family is so scattered we don't have reunions anymore. It saddens me. My immediate family will get together on occasion when my grandparents visit, but not regularly. My family went through too much upheaval to hold together. I'm not sure we'd know what to do at a reunion.
Treasure your reunion and really get to know your family.
What talent your family possesses! Your sister's design skills – and your writing skills amaze me! I'm a fanatic of the color purple so of course this floral arrangement really caught my eye!
enjoy that family reunion of yours!


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Is wearing red now a crime in Uganda?
- Written by Editorial
A very unfortunate incident that must not go unreported happened in Kampala on Tuesday, October 3.
Pupils of a primary school in Kyebando, who were travelling with their teachers to attend an official event at Nkumba University in Entebbe municipality, were intercepted and beaten up by goons associated with a group called Boda Boda 2010 Association.
The children's crime was apparently wearing their red uniform or costume, which, to these men, suggested they oppose the ongoing efforts to lift the presidential age limit in the Constitution. How did we get here?
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Sadly, we can't say we didn't see this coming. Ever since the government expressed support for the proposal to amend the Constitution and scrap presidential age limits, almost all state machinery has been deployed to promote the proposal, while at the same time putting significant bottlenecks in the way of anyone opposed to it.
Overzealous individuals and groups, both within and out of the government, have taken advantage of this situation to unleash harassment against those deemed to stand in the way of President Museveni's continued stay in power.
Last week's fracas in parliament, the gagging of targeted individuals in the media, the arrests of people for the flimsiest of reasons, are all to be understood in this context.
Now, it looks as if the authorities consider the wearing of a red bandana alone, or any red head dress for that matter, which those opposed to the amendment have identified as their symbol, to be a criminal offence.
One risks assault and arrest if they are found in possession of or wearing one. By the time you explain your non-political agenda, you might be in jail or hospital, as these unfortunate children and their teachers found out.
Since when has red colour been outlawed and what's wrong with anyone expressing a view that is contrary to that of the government and its supporters? What happened to the freedom of expression enshrined in the Constitution?
Sad and embarrassing as it is, this incident is an eye-opener. The police practice of using ungazetted individuals and groups to do dirty jobs is very dangerous.
When and why in the world did these "Rebels" begin opposing the lifting of "Age limit" from our Constitution?
Worse still, where was Kaihura and his goons? Why didn't they apprehend these rebels? Has he forgotten that donning anything RED is prohibited in Uganda?
Eeeeeeh....Uganda. Cry, the beloved Country!
I was born immediately after Uganda's independence and lived through all the past governments but never a single day did Uganda witness the beating of innocent school children by state operatives.
Some one has to pay for this and I will not rest until I get justice for my child through any means within my power.


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Do We Always Want What We Can't Have?
Maybe fate has it or maybe it's just in our DNA, but it is a truth universally acknowledged that the minute us girls find someone that is hard to get we'll jump into the challenge without second guessing. Most of us don't even realize it, until it is way too late and we have once again placed ourselves in yet another complicated and potentially painful situation. I have neglected my blog for quite a while now, partly because of the huge amount of work that I have to do and partly because I didn't know how to share what happened in the past month and what I had learnt from my experience.
I spent Christmas at home this year, and left London for two weeks. As much as this was a time that I was looking forward to, I knew that I would eventually have to face Mat (see Will he ever leave his girlfriend for you?). As much as I say that I have gotten over him and as much as I moved on, no one could ever replace him and I always knew that given the chance I would go running back to him, even for one last time. I was too embarrassed to admit this even to myself, let alone publish it on my blog. But given the circumstances, and what has happened I decided that it's time I'm completely honest with you. I was back home for three days before I saw Mat, and even before that I was contemplating on the immense amount of emotions that would surge through me when I saw him. I wanted to be rational and say that I would be happy to see him but wise enough to not go back to him again or try to approach him... but by now we all know that what we feel is by no means rational. I couldn't figure out if I would feel sad, happy, content or even angry. I wanted to believe that I was still angry at the way he treated me and I never wanted him anywhere near me again, but deep down I knew that I had already forgiven him and still loved him.
And so some days passed until one day I saw him, and in the blink of an eye I forgot all my rationality, hell I even forgot how to breathe for a minute and it all came rushing back. I could feel once again all the love I had for him and all the pain. I barely talked to him that night, but I knew that I would see him again after that. And it didn't even take long for him to contact me: by the next afternoon we had arranged a meeting later that night at his place. I knew how wrong it was after everything he has done to me, but it was beyond me to not see him again after so long of thinking about him and missing him. And maybe it was weakness, or maybe thoughtlessness, but the minute that he contacted me I knew it was what I wanted.
When the time to see him approached I was unsettlingly calm – I was half expecting me to be panicking, thinking it over and over again and even asking my friends' opinions. But I was too embarrassed to admit that I was going to see Mat again and the last thing that I cared about that night was my outfit, my hair or my make-up. When he opened the door to greet me it was like no day had passed by. When we had sex it was exactly like I remembered it – still the best sex of my life... but then something extremely weird happened: there was nothing left to say. None of us wanted to talk about the past year, and there was no point in doing so; we knew nothing would change. We also knew that after that night, we would probably never see each other... maybe for a long time or maybe never. This was by no means a start to something new, just a mistaken memory of the past being relived for just one night. At this point I have to ask you to excuse my slightly romantic and dazzled way of writing, but even a month later I still don't know how to phrase everything that happened with Mat during Christmas, and this might be my slightly nostalgic and confused way of writing. So we didn't talk about ourselves, or how the past year was. We chatted a bit about what was going on in our lives, regarding work and the holidays. But all the while Mat was looking at me from the other end of the room, talking to me as if talking to a someone slightly more than an acquaintance and recalling how much we used to be a part of each other's life in the past, I couldn't help but wonder: Was I really still in love with Mat or was I just so addicted to the exquisite pain that comes with wanting someone so unavailable to you? By this point I'm still confused, we said goodbye like we were to see each other again soon, but by the time I got into my car and drove away we both knew that was a lie... and whatever we had in the past had ended. For some reason, maybe it was the year that passed by or the pain that made us grow apart, but whatever Mat and I were was finished... we had become something else, and even I couldn't define it and I'm still not able to. I returned back to London without seeing him again and still at a state of confusion. I desperately wanted to believe that I had made the wrong decision going back to see him again after so long--- but somehow it felt that I hadn't. A part of me was breaking inside for not being the way I was with him, but another part, a more confused one, realised that Mat and I were not the same people anymore together.
A week after I came back to London I went for a night out with Javier. I desperately wanted to tell him what happened and how confused I was, but I was too embarrassed to admit it. So I made an extremely rational decision at the time: I would tell him after a couple of glasses of wine. But the couple of glasses of wine turned into one-too many glasses and before I knew it we were in a bar with a few of his friends, which is when I met Harry. I had heard about him through Javier, but never really got to meet him. To make a long story short, I talked for a bit with Harry and found out that he was separated from his wife, with two children, not willing to commit to any other relationship at the moment and extremely frustrated with his life. In other words, the guy might as well have had a huge sign on his forehead: 'Do Not Date Me'. So naturally, I made the most rational decision: I gave him my number when he asked for it! I know what you are thinking, why did I do this, what I was thinking and truth is, I wasn't! I was a bit drunk, I wanted to put whatever happened with Mat behind me and I wanted to move on. He asked me out on a date two days later, where he repeated how frustrated he was with his life, how unstable his life was and how much he didn't want to be with anyone right now. I wanted to shut everything out, I wanted to forget about what had happened with Mat and I wanted to move on with Harry; after all how much could he mean everything he had said... twice? And did I mention he is really sexy? I'm not sure what it is that made me decide this, but by the end of the night I had slept with him... twice.
I hated the idea of spending the night in someone else's bed so around 2 o'clock in the morning I made my way home... which is where I realised it: I didn't care how sexy Harry was, or how much I even liked him... he was just another unavailable man! He was just another yet-to-be disappointment. He was like a car-crash I was driving right into with no intention of avoiding. I wanted to move on from Mat, but I wanted to replace him with something just as excruciating and painful... Once again, I wanted what I couldn't have! And it didn't even surprise me... And I'm not the only one out there. As soon as we see a guy who is unavailable to us and we develop even the slightest interest for him, the it's like a project: we need to have him! We will freeze hell over in order to make him be with us the way we want him to, just because we can't have him the way we want to. And coming to think about it really, it's more masochistic than enjoyable... Unless we come to think of it as enjoyable precisely because it is masochistic. I decided I wouldn't stick around long enough to find out. I stopped seeing Harry right then and there, and never returned his calls after that. I hope he finds what he is looking for, but he is definitely neither what I am looking for nor what I need right now in my life!
As for Mat, I might see him again in a year or more, I might never go back to him again.... I still don't know. But at least now I do know, that whatever Mat and I were is finished and we will never go back to the way we were... the only thing that kept me so stuck on him this whole time was my addiction to the pain that he put me through; and I still haven't shaken that habit. But as exquisite as that pain is, I refuse to replace Mat by eventually replicating the pain he put me through with someone else. I will probably find something else, but for the time being I have to make a conscious effort to pick the guys in my life more wisely!
What do you think? Have you ever wanted someone exactly because you couldn't have them? If so, how did it turn out? Comment and let me know!!


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PORTSMOUTH is one of the world's premier waterfront cities and is up there with the likes of San Francisco and Tokyo, says Emirates boss Sir Tim Clark.
And he said that was another reason why he was so eager to see his airline firm invest.
'I have been to many waterfront cities around the world, but I think Portsmouth rates among one of the best,' he said.
'People talk about San Francisco and Tokyo, but I love Portsmouth.
'It's too much of a well kept secret.
'We need to go out and tell people about it. It has beautiful views, and has a fantastic maritime history.
'There are a mosaic of opportunities here.' Sir Tim was also asked who he wanted to see win the America's Cup, given his company sponsors participant Team New Zealand. He said being British meant he would like to see Sir Ben Ainslie's team succeed.
'If Ben Ainslie and his team win, then the UK gets to hold the America's Cup in an area of their choosing, which would be more than likely in UK waters, and make Portsmouth and the Solent very important.'


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Eastern Wash. wildfire now estimated at 2,500 acres
POMEROY, Wash. - A wildfire that has burned through thousands of acres in eastern Washington is now estimated at 2,500 acres.
The blaze is being called the Snake River Fire. The fire was estimated at 3,000 acres Sunday evening, up from 500 acres that morning.
The fire is burning downstream from the Nisqually John Landing on the south side of the river in Garfield County.
State authorities say the fire will mainly be handled by hand crews due to steepness of the terrain.
State Mobilization crews took over the fire Sunday and brought in fire resources from around the region. They also brought in helicopters and planes to help.
Fire authorities say they believe lightning started the fire around 1:30 a.m. Saturday.


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Audio Syncing
AUdio Syncing
You can adjust the audio offset in OBS to fix any syncing issues between your audio and video. This won't show up in the preview window, but only after watching back a recorded clip.
To adjust the offset, click the gear icon next to Mixer in the main OBS window. This is right above the Mic/Aux bar in the middle. Change the Sync Offset (ms) value to something around 750. This is in milliseconds; 1000ms is 1 second.
Close the window, and start a recording. Talk for a bit then clap a few times. Watch the video back to check the syncing. Keep testing and adjusting the offset until all looks good.
Keep in mind that this offset depends on how heavy a load your computer is under at the time of recording or streaming. This means, if you test while exporting a video (heavy load), but record after it's finished, your offset may need to be adjusted to account for the new conditions.
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Mahesh Bhatt's daughter who is all set to make debut in bollywood with movie "Student of The Year" has glammed the covers of Vogue India magazine in its September 2012 issue.
This was Alia's first fashion shoot and she wore dresses of international brands like Jenny Packham and Blumarine. At the age of 19, Alia is just a stunner while looking through the pictures in Vogue magazine.
"Student of the Year" is releasing on 19 October, so lets watch her in her first silver screen appearance.


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