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Crossover inhibition in the retina: circuitry that compensates for nonlinear rectifying synaptic transmission
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In the mammalian retina, complementary ON and OFF visual streams are formed at the bipolar cell dendrites, then carried to amacrine and ganglion cells via nonlinear excitatory synapses from bipolar cells. Bipolar, amacrine and ganglion cells also receive a nonlinear inhibitory input from amacrine cells. The most common form of such inhibition crosses over from the opposite visual stream: Amacrine cells carry ON inhibition to the OFF cells and carry OFF inhibition to the ON cells ("crossover inhibition"). Although these synapses are predominantly nonlinear, linear signal processing is required for computing many properties of the visual world such as average intensity across a receptive field. Linear signaling is also necessary for maintaining the distinction between brightness and contrast. It has long been known that a subset of retinal outputs provide exactly this sort of linear representation of the world; we show here that rectifying (nonlinear) synaptic currents, when combined thorough crossover inhibition can generate this linear signaling. Using simple mathematical models we show that for a large set of cases, repeated rounds of synaptic rectification without crossover inhibition can destroy information carried by those synapses. A similar circuit motif is employed in the electronics industry to compensate for transistor nonlinearities in analog circuits.
KeywordsRetina Linearity Rectification Inhibition Visual processing Neural circuitry Synaptic nonlinearity
1 Introduction
Retinal and cortical processing requires that some visual pathways retain a linear representation of visual signals. However, signal transmission across synapses and via spike generation is inherently nonlinear and rectifying. This rectification distorts the original visual signal and can destroy information in a given pathway because signals that fall below the rectification threshold are compressed. How, then, is linearity maintained in the face of rectification? In this paper we will show that in many cells, inhibition between the ON and OFF pathways acts to suppress the effects of synaptic rectification.
The retina parses the visual signal into two complementary visual streams; the ON and OFF pathways that first appear at the bipolar cells (Dacey et al. 2000; Kaneko 1970; Werblin and Dowling 1969). In these same cells, OFF cells receive ON inhibition and ON cells receive OFF inhibition (Molnar and Werblin 2007). A similar interaction takes place among amacrine cells (Hsueh et al. 2008) and ganglion cells (Roska et al. 2006). Recent work indicates this inhibition is predominantly glycinergic (Hsueh et al. 2008; Manookin et al. 2008; Molnar and Werblin 2007; Wassle et al. 1986). We refer to this class of inhibition as "crossover inhibition" because it is carried by amacrine cells that carry signals across the ON/OFF boundary of the IPL There is evidence that additional forms of crossover inhibition continue in the lateral geniculate and at different levels in the visual cortex as well (Hirsch 2003).
The commonality of crossover inhibition, dominating more than half of the cell types in the inner retina, suggests that it performs an important function in the retina; yet crossover inhibition seems redundant: When light levels increase, the excitation to OFF cells intrinsically decreases, and it is not obvious how reinforcing this reduction with increased inhibition from the ON system would enhance the response of the cell.
Several possible functions for cross-over inhibition have recently been suggested. Recent work by Manookin et al. (2008) suggests that cross-over to OFF ganglion cells enhances the sensitivity (gain) of these cells to small changes in brightness at low light levels. Renteria et al. (2006) suggest that this same cross-over may act to suppress spurious ON signals that otherwise appear in the OFF pathway. We demonstrate here that crossover inhibition acts to suppress the distorting effects of synaptic rectification. The excitatory and inhibitory currents that impinge upon a given cell are rectified, but in opposing directions, so their recombination generates a membrane voltage representation of the visual signal that is more linear than either of its inputs. This is especially important in the subset of retinal pathways that respond to the average light intensity across their receptive field, distinct from the (nonlinear) pathways that selectively respond to local contrast. We further suggest that maintaining linearity in the temporal domain, at least in some retinal outputs, is necessary to prevent information loss due to interleaved rectification and adaptation. A similar "crossover" circuitry is routinely implemented in analog electronic circuits to perform all of the suggested functions of crossover in the retina, including compensating for the nonlinearities introduced by transistors.
In this study we look at crossover inhibition and rectification in several ways. First we review the basic evidence for, and spatial-temporal behavior of crossover inhibition. We then present evidence for the commonality of synaptic rectification, evidence that crossover inhibition suppresses the effects of this rectification, and a simple model that captures both of these effects. Using a combination of experimental and computational results, we then show why correcting for rectification at each stage of the retina is important even when this correction is followed by further rectification. Finally, we present some computational evidence for why a combination of synaptic rectification and crossover inhibition provides better signaling performance than simple linear synapses.
2 Methods
Eyes were extracted from rabbits and dissected as described previously (Roska et al. 2006). Ganglion cell recordings were made in flat mount (Fried et al. 2005; Roska et al. 2006), while amacrine and bipolar cell recordings were made from 250 μm slices (Molnar and Werblin 2007). Spiking in ganglion cells was recorded using loose attached patches. Excitatory and inhibitory currents were recorded under voltage clamp at -60 mV and 0 mV respectively. Membrane voltages were recorded under 0pA current clamp. Cell types were identified by imaging with Alexa Fluor 488 and comparing with previous work (MacNeil et al. 2004, 1999).
Slice mounted cells were stimulated by 200 μm wide light and dark flashes and sinusoidally varying intensities of ± 100%, relative to a set background illumination of 3 × 105 photons/μm2/s. Ganglion cell receptive field centers were found by flashing spots of varying size, from 100 μm to 1000 μm and recording spikes, excitation and inhibition. Sinusoids and gratings were sized to match the maximal spiking flash response for each cell. Gratings took the form of 50 μm, 75 μm and 100 μm stripes of ± 100% relative to background, and were flipped every 0.5 s. "Full" gratings were used, where each stripe was either 100% or -100% relative to the background, and each stripe was inverted at each transition. In the case of these gratings, every location on the grating saw a change at every transition but the average intensity across the whole grating was held constant. We also used two "partial" gratings where half of the stripes were held at background, such that all the remaining stripes were either 100% or -100% relative to background, and switched at each transition, driving ½ of the receptive field, but with a change in average intensity. The two partial gratings use complementary subsets of stripes such that in combination every stripe was driven. Conceptually, the full grating is just the sum of the two partial gratings.
Based on this metric, excitation to purely ON cells give a P = -1, and to OFF cells, P = +1. Similarly, ON inhibition has P = +1, and OFF inhibition has P = -1. ON-OFF responses give -1 < P < 1, with the sign defining the dominant (ON vs OFF) input.
Cells were defined as receiving crossover inhibition, and so were included in the various analyses described below if the polarity numbers for excitation and inhibition had the same sign (implying opposite changes in conductance). We also excluded cell types for which electrical coupling degraded the effective voltage clamp to the point where we could not distinguish excitation from inhibition, specifically, we excluded AII amacrine cells, which are readily identifiable by both anatomy and physiology (Hsueh et al. 2008) and which show strong electrical coupling to one another through gap junctions.
Amplitude-modulated sine waves were analyzed by taking the Fourier transform of the response, extracting the phases for the fast and slow frequency terms, and taking the difference in phase between excitation and inhibition at each of these frequencies. Because phase is meaningless for cases where the slow (artifact) signal was below noise levels for either excitation or inhibition, we culled all cells from this analysis where either excitation or inhibition was less than the noise level at adjacent frequencies; this resulted in culling approximately ½ of cells from the modulated sine-wave analysis.
A more detailed description of the Methods can be found in the study of Molnar & Werblin (Molnar and Werblin 2007)
Modeling methods
In all cases, membrane voltage is modeled as a weighted, signed summation of excitation and inhibition.
Simulations were performed in MATLAB. For the simple simulations shown in Fig. 7 and Fig. 10, inputs were passed through a simple linear time invariant high-pass filter (as in Eq. (9)), as well as a difference-of-Gaussians model of the outer retina for Fig. 10. Differential equations were modeled using difference equations iterated across many time-steps: time steps were made very small relative to the time-constants of the differential equations to avoid numerical artifacts: dt = 0.001τ. The rest of the model consisted of a series of static computations (ie rectification, cross-subtraction). At each time-step, input was drawn from a previously arranged time series. The input was multiplied by + 1 and -1 to generate the two ("ON" and "OFF") pathways. Half-wave rectification was then applied to both signals, modeled by the Boltzmann distribution taken to the 4th power (Eq. (5)).
For the model in Fig. 12, similar components were used but in a slightly different order: the input was first parsed into ON and OFF pathways, then rectified using a Boltzman distribution (Eq. (5)) as above. This was followed by an LTI filter (Eq. (9)), as above, and followed by a simple piece-wise linear rectifier (Eq. (7)), to model spike generation. Crossover inhibition (shown in Fig. 12(b)) was modeled by subtracting the two high-pass filtered signals before the final round of rectification.
Finally adaptation, modeled in Fig. 13, involved a similar process, but with each synapse including both a rectifier as in Eq. (5) and a linear-time-varying model of adaptation (as in Eq. (8)). The action of two such synapses were computed in series for each pathway, followed by piece-wise linear rectifier (Eq. (7)), to model spike generation. Crossover inhibition was modeled by subtracting the signals after each synapse model, but before the subsequent round of rectification. For simplicity, we decided not to model the additional effects of the intermediate cells and synapses and treated them as mirroring the action of the "bipolar" cells.
3 Results
3.1 Basic characterization of crossover inhibition
Frequency of crossover inhibition and average rectification in various broad cell classes
General cell class
fraction with crossover
R ( degree of Rectification)
raw #
By type
44/48 (48/48)
5/6 (6/6)
26/49 (38/49)
2/5 (3/5)
38/86 (62/86)
6/13 (11/13)
ON ACa
90/119 (106/119)
12/17 (16/17)
44/67 (67/67)
4/5 (5/5)
10/67 (54/67)
1/5 (4/5)
Pharmacological experiments performed by our lab and others (Hsueh et al. 2008; Manookin et al. 2008; Molnar and Werblin 2007) have confirmed that these signals cross over from ON to OFF pathways by using L-AP4, which selectively blocks the excitatory inputs to ON bipolar cells(Slaughter and Miller 1981). L-AP4 has been shown to reliably block inhibition, but not excitation to OFF bipolar, amacrine and ganglion cells. Similarly L-AP4 reliably blocks excitation to ON cells, but in the majority of cases does not block crossover inhibition, revealing OFF inhibition to ON bipolar, ON ganglion and especially ON amacrine cells. Examples of the effect of L-AP4 on cells receiving crossover inhibition are shown in Fig. 2(d).
Crossover inhibition is common, but not universal, and the distribution of this crossover inhibition across cell types is not symmetric: crossover inhibition was the dominant form of inhibition in almost all OFF bipolar and ganglion cells, and in nearly all ON amacrine cells, but was found to dominate in only about half of OFF amacrine cells, and in less than half of ON bipolar and ganglion cells. Crossover inhibition was also found in combination with other types of inhibition, especially in those cells types where it was not usually dominant (i.e. ON ganglion cells). The distribution of crossover inhibition across different cell types, based upon previous work in our lab (Hsueh et al. 2008; Molnar and Werblin 2007; Roska et al. 2006), is summarized in the first three columns of Table 1.
An alternate possible circuit that could generate the same basic excitatory and inhibitory responses in Fig. 3(c,e and f) would be a circuit involving two amacrine cells in series: For example an amacrine cell providing apparent ON inhibition could depolarize at light on due to direct excitation from an ON bipolar cell, or because of reduced inhibition from an up-stream OFF amacrine cell. In this second case the final inhibition would appear to be "ON" inhibition but would actually originate entirely from the OFF system. APB results from our lab and others (Hsueh et al. 2008; Manookin et al. 2008; Molnar and Werblin 2007) indicate that in most cases this is not the dominant circuitry supplying crossover inhibition. However, given the commonality of crossover inhibition to inner retinal interneurons, it is likely that most inhibitory signals come from interneurons (amacrine or, indirectly, bipolar cells) which themselves received crossover inhibition. Thus, crossover inhibitory signals are likely to reflect a combination of true crossover signaling and indirect within-layer cascaded inhibition.
In the basic flash responses shown in Figs. 2 and 3, excitation and inhibition do not appear to overlap: when excitatory conductance is maximum (as indicated by large inward currents) inhibitory conductance is at a minimum (as indicated by a small outward current), and when inhibitory conductance is maximum (large outward current), excitatory conductance is minimum (small inward current). This leaves the question: what function does crossover inhibition provide?
Linear model of crossover inhibition
Linear signal processing is defined as any operation whose output can be described as a weighted average of the input (light signal) across time and space. Under this approximation, the ON system encodes increments in light intensity and the OFF system encodes decrements, but both systems are capable of encoding both increments and decrements. A decrement in intensity would lead to a decrease in activity in the ON system as well as an increase in the OFF system. These pathways may be modeled linearly as representing the same signal (changes in intensity) but with opposite signs. Thus for an input light signal u(t), the responses of the ON and OFF systems could be represented as x ON = u(t), and x OFF (t) = -u(t).
Thus because both excitation and crossover inhibition represent the same intensity change with the same sign, crossover would seem to perform little in the way of real signal processing aside from increasing signal gain (Manookin et al. 2008). What, then, is the functional significance of crossover inhibition?
3.2 Synaptic inputs are rectified, crossover inhibition compensates for this rectification
There is also the possibility that crossover is important for dealing with nonlinear processing. As Figs. 2 and 3 show, synaptic inputs to crossover cells are not simply linear representations of the light stimulus, which would show equal but opposite size steps in activity at the onset and termination of a stimulus. Instead, these inputs are rectified, encoding presynaptic depolarization much more strongly than hyperpolarization. A linear system such as described by Eq. (10) will encode the onset and offset of a flash symmetrically, whereas a pathway with rectification will respond to positive and negative signal changes with different magnitudes, distorting the linear response. As such, symmetry of a flash response can be used as an indicator of how linear the pathway that generated that response is: less symmetric responses imply a less linear, more heavily rectified signal pathway.
For example, looking again at Figs. 2 and 3, one can observe in the example cases that membrane voltages show roughly symmetric hyperpolarization and depolarization at light ON and OFF. However, the synaptic currents and spiking responses are much less symmetric, showing a large degree of rectification. In Fig. 3, the OFF excitatory signal showed a large increase in inward current at light OFF (a downward deflection) but only a weak decrease in this current at light ON. Similarly, The ON inhibitory current shows a large increase in outward current (an upward deflection) at light ON, but no decrease at light OFF. Thus, each synaptic input showed a complementary rectified response, with a large increase in conductance (and so current) when its presynaptic cells are depolarized, and a weak decrease in conductance when its presynaptic cells are hyperpolarized. The membrane voltage, however, showed a more symmetric response. We measured a depolarization at light ON, and equal but opposite hyperpolarization at light OFF. Thus, the combined currents, expressed as membrane voltage, create a representation of the stimulus that is much more symmetric, implying a more linear representation of the signal.
Rectification is a general property of crossover circuitry
The results shown in Fig. 6 and Table 1 indicate that in general excitation and crossover inhibition to inner retinal neurons are rectified: they respond more strongly to presynaptic depolarization than to presynaptic hyperpolarization. But, on average, the combination of excitation and inhibition results in voltage responses that are significantly more symmetric. However, these voltage responses are quite variable in their degree of rectification, as shown in Fig. 6. This variability is almost certainly due in part to experimental variation: bipolar and amacrine responses were recorded from retinal slices, which tend to cause some damage to the recorded cells' dendritic and axonal trees as well as to the presynaptic cells which drive them. Such damage will result in a randomly reduced magnitude of the inputs which is not necessarily the same for excitation and inhibition. This damage may also cause some leakage in post synaptic cells, shifting their resting potentials, and so altering the driving force associated with different synaptic channels. Thus, the relative weighting of excitation and inhibition in a given cell will almost certainly be somewhat shifted from its normal physiological state, increasing the apparent variability in membrane voltage rectification.
These average responses also encompass a wide variety of subtypes (as indicated in Table 1), not all of which are necessarily linear: indeed, known nonlinear OFF ganglion cell types have been shown to receive crossover inhibition (Zaghloul et al. 2003) indicating that crossover inhibition does not necessarily imply a linear response. Similarly, since a subset of ON ganglion cells have been shown to be linear (Chichilnisky and Kalmar 2002) even though most ON ganglion cells do not show purely crossover inhibition, linearity is possible without crossover inhibition, provided that the synaptic inputs are linear. This raises the possibility that the improvement in average voltage symmetry seen in Fig. 6 and Table 1, is a consequence of out-lying nonlinear cells, and that the more linear part of the population maintains this linearity because of intrinsically symmetric synaptic inputs, and not as a consequence of rectified crossover inhibition balancing rectified excitation.
To confirm that our population findings apply to linear cells (those with relatively symmetric voltage behavior in responses to flashed stimuli), we selected linear subsets of bipolar and amacrine cells (where we had significant amounts of voltage data) by only considering those cells whose voltage responses are reasonably symmetric. Specifically, we chose a threshold level of rectification, R thV (where 0 < R thV < 1) and only considered cells for which |R(V)| < R thV , eliminating the cells with the most distorted voltages from consideration. The question we wanted to ask was: do cells with linear (symmetric) voltages show linear synaptic inputs as well, or are their inputs rectified, such that their linearity is a consequence of crossover inhibition.
In OFF bipolar, and ON and OFF amacrine cells, excitation and inhibition were consistently less symmetric (|R| was larger) than voltage, over the full range of possible values for R thV , with excitation consistently showing negative R numbers, and inhibition showing positive R numbers. More to the point, the magnitude of the rectification in excitation and inhibition was not significantly smaller for cells with symmetric voltage responses than for the population as a whole; even for the most linear subsets of cells, excitation and inhibition were still fairly asymmetric, with an average R greater than 0.2 in magnitude. The exception to this rule was in ON bipolar cells, where excitation was consistently more linear than voltage until R thV was reduced below 0.3. This implies that 1) symmetric membrane voltage in response to light does not imply symmetric inputs from individual synaptic inputs (that is a linear voltage does not imply linear synaptic input), and 2) where voltage response is symmetric but synaptic input is not, crossover inhibition provides the balancing input to correct for synaptic rectification.
A simple model of rectification and crossover inhibition
Crossover inhibition has several properties that are closely analogous to differential electronic circuits. Such circuits encode signals in two parallel pathways which undergo similar filtering and amplification, and which are subtracted from each other at each stage of processing. Differential circuits, among other reasons, are often used specifically to suppress certain types of nonlinearity, in particular, rectifying nonlinearities from transistors. Since synapses and spiking mechanisms have been shown to cause rectification in many cases (Katz and Miledi 1967), it seems reasonable to hypothesize that crossover inhibition might act in a similar fashion.
Which shows a larger change for positive changes in input (x > 0) than for negative changes (x < 0). Similar asymmetry can be seen for other models of rectification, such as a piecewise linear model, or a sigmoid operating at voltages below its inflection point (see Fig. 1, Methods).
And, in the ideal case, the even-order terms are eliminated (Magoon et al. 2002), yielding a perfectly linear output. As shown in Fig. 7(b), this simple model combined with some basic high-pass filtering predicts qualitatively similar results to those shown in Fig. 3. The elimination of even-order terms such as shown in Eq. (18) requires a perfect balance between the ON and OFF inputs, and so is unlikely to occur in real life. Nonetheless, even if they are imperfectly matched taking the difference between Eqs. of the form in (16) and (17) will lead to a result with a weaker 2nd-order term relative to the linear term. Similarly, even if crossover inhibition does not exactly match excitation, it will still lead to a suppression of rectification and its effects, as shown in Fig. 6.
3.3 Crossover inhibition suppresses artifacts generated by successive stages of synaptic rectification
Figures 2, 3, 4, 5, 6 and 7 indicate that while synapses tend to rectify the responses to light flashes, crossover inhibition will tend to suppress the effects of that rectification. However, this suppression appears futile, since in each case, once the voltage is relinearized by crossover inhibition, the signal is rectified again at each subsequent stage of synaptic transmission, or by spike generation. For example, compare Fig. 3(f), which shows a linear ganglion cell voltage representation of a light flash, with Fig. 2(c), which shows the final (strongly rectified) spiking response of a similar cell. What benefit, then, does crossover inhibition provide by correcting rectification, if the signal is re-rectified at the next processing stage?
Even though we cross-subtract in the end, there is now a (3rd-order) distortion term that is solely a consequence of the rectifying nonlinearities, but which is insensitive to the final cross-subtraction. This distortion term is especially important since it tends to amplify large signals more than small ones, effectively reducing the system's gain (and so sensitivity) to small, hard-to-detect inputs compared to its gain on already large (and easily detected) inputs.
However, if this signal is subjected to a second order nonlinearity such as in Eq. (15) the strongest additional spectral component that appears is at frequency f 2 (the modulation frequency) which was not present in the original signal, and which may be at significantly lower frequencies than the input.
This becomes a problem in systems where subsequent filtering, such as described by Eq. (10) is intended to suppress some frequency bands and not others. Rectification plus filtering, then, can generate ambiguities between very different inputs, or, as we will show below, can even destroy information altogether. By correcting for rectification, and suppressing its artifacts before subsequent processing, cross-subtraction in differential circuits remove these ambiguities.
We found this phase relationship between excitatory and inhibitory currents across OFF bipolar cells (N = 9), ON (n = 10) and OFF (n = 9) amacrine cells and OFF ganglion cells (n = 6). ON bipolar and ganglion cells, which generally show relatively linear excitatory inputs and less crossover inhibition, were not included in this analysis. We performed this analysis for three different combinations of fast- and slow- stimulation frequencies: 0.3 Hz × 1.2 Hz, 1.2 Hz × 4.8 Hz, and 0.3 Hz × 4.8 Hz, in order to confirm that the activity of crossover inhibition was broad-band. As shown in Fig. 4(d-f), the original frequency components remained in phase across different frequency combinations (1º ± 30 º, mean ± s.d.) such that inhibition enhanced excitation when transmitting the original signal. The rectification artifacts present in the synaptic currents, however, were out of phase (188º ± 50º), and so suppressed each other in the output voltage. This was independent of "carrier" frequency and showed only a weak sensitivity to modulation frequency, where a slight phase delay was seen in the artifact for a 1.2 Hz modulation (204º) relative to slower, 0.3 Hz modulation (180º and 182º) Thus, crossover inhibition enhanced the original response and suppressed rectification artifacts independant of the temporal scale of these two signals. It is important that rectification artifacts are suppressed at multiple stages in the retina, including bipolar and amacrine cells, as well as ganglion cells, since additional processing, such as temporal filtering, will tend to shift the relative phases and amplitudes of signal and artifact, potentially preventing them from being separated in later processing.
Crossover inhibition suppresses spatial artifacts generated by synaptic rectification
We quantified linearity with a measure L (see Methods), reflecting the relative response to partial versus full gratings. Histograms of L across 9 OFF cells and three different spatial scales are shown in Fig. 9(d): L = 1 corresponds to a perfectly linear response, L ≤ 0 corresponds to an extremely nonlinear response. This sample included a variety of subtypes, of which 4 were relatively nonlinear (L < 0.5, corresponding primarily to alpha and delta cells) and the rest of which were quite linear (beta and parasol cells); However, regardless of their baseline linearity, all of these cells showed less linear responses under APB, with cells that started out less linear changing slightly less under APB (correlation coefficient between initial linearity and change in linearity under APB = 0.3). Overall, the linearity of OFF ganglion cells decreased under APB by -0.38 ± 0.46 (mean ± s.d) p = 6 × 10-4 (Wilcoxon signed-rank test), and recovered under wash to values equivalent to control (p = 0.46). Thus, linearity in OFF ganglion cells is not inherent to the feed-forward pathway that drives them, but is actively maintained by crossover inhibition from the ON system.
This interaction is modeled in Fig. 10. We start by treating the input is having two regions, with each region feeding into ON and OFF pathways, both of which contain some adaptation (high-pass filtering). Thus for partial gratings, one of these regions is stimulated but the other is not, yielding very different responses (compare red vs pink for model bipolar cells, blue vs cyan for model amacrine cells). These signals are then all rectified, and summed in a single ganglion cell. For partial gratings, excitation and inhibition are largely non-overlapping, as in Figs. 2 and 3, and the resulting sum is re-rectified to generate spiking: inhibition has no effect on the output, and removing it has no effect. However, for full gratings, both pathways are activated, resulting in an overlapping of excitation from one region with inhibition from the other. Thus, the inhibitory ON signal from one region suppresses the OFF inhibition from the other, and no spiking results. However, if this ON inhibition is suppressed, then excitation is no longer blocked, and significant spiking results.
Ganglion cells combine and average the inputs of many bipolar and amacrine cells. For purely linear pathways, this summation acts to average or "low-pass filter" the visual signal across space, responding selectively to features on the same spatial scale as the cell's receptive field, and suppressing responses to smaller features. As seen in both Fig. 10 (a and b), if the averaging is performed across a set of signals with the same polarity of rectification, then this selectivity is lost, and the cell responds to stimuli with a variety of feature sizes. This difference is seen even though the final output is rectified by spike generation in both cases. Although the second round of rectification masks any hyperpolarizing effects of crossover inhibition, it does not mask the effects of crossover when low pass filtering occurs between stages of rectification. The basic implication is that low-pass filters, when inserted between rectifying stages, lose their selectivity if the preceding stage is not compensated by crossover inhibition.
If interleaving rectification with low pass filtering disrupts the selectivity of that filter, how does interleaving rectification with high- or band-pass affect the system response?
1) x > 0, dx/dt > 0, 2) x < 0, dx/dt < 0, 3) x > 0, dx/dt < 0 and 4) x < 0, dx/dt > 0. In the first case, ON = dx/dt, OFF = 0, and in the second case, ON = 0, OFF = -dx/dt, such that the input x (really its derivative) is encoded in the difference of the outputs. In the other two cases, however, where the input and its derivative have opposite signs, both ON and OFF are zero. This implies that for half of all input scenarios, the output of the system conveys no information about its input.
Thus, whereas low-pass filtering between rectifying stages leads to reduced selectivity and increased activity in both ON and OFF pathways, high-pass filtering interleaved with rectification has the capacity to entirely destroy information.
4 Discussion
Crossover inhibition provides circuitry that compensates for the nonlinear behavior of synapses, so that linear signal streams can be maintained through the visual pathway. This crossover inhibition combines rectified excitatory currents with rectified crossover inhibitory currents to reconstruct a linear, non-rectified membrane voltage in bipolar, amacrine and ganglion cells (Figs. 1, 2 and 3). This reconstruction suppresses artifacts in time (Fig. 9) and space (Fig. 10), maintaining linear activity throughout the retina. The crossover signals are inhibitory in the conventional sense: they are usually mediated by glycine and modulate chloride channel conductance (Hsueh et al. 2008; Molnar and Werblin 2007; Wassle et al. 1986). Functionally, however, crossover inhibition responds to stimuli by driving membrane voltage with the same polarity as excitation, hyperpolarizing the cell when excitation is weak while disinhibiting the cell when excitation is strong. So, from a linear perspective, crossover inhibition acts in concert with and serves to augment, rather than suppress excitation. This augmentation appears to hold across a variety of spatial and temporal scales, such that inhibition enhances excitation across a wide range of spot sizes and for stimuli ranging from 2 s flashes (Fig. 2 (a-c)) to 10 Hz sine waves (Fig. 4).
This matching in time is slightly surprising given that crossover pathways imply at least one additional neuron and synapse, which should cause some delay. It seems that either the cells and synapses involved are sufficiently fast compared to the bandwidth of the stimulus (10 Hz) so as to not affect this phase, or that the synapses act in some way to equalize the phase delay intrinsic to the crossover pathways. The speed of this transmission is not entirely surprising given that most evidence points to crossover inhibition being carried by glycinergic amacrine cells(Hsueh et al. 2008; Manookin et al. 2008; Molnar and Werblin 2007) such that inhibitory synaptic transmission will be relatively fast (Eggers and Lukasiewicz 2006). Furthermore since vertically oriented, glycinergic cells are generally thought to have narrow dendritic fields (MacNeil et al. 1999; Wassle et al. 1998; Wassle et al. 1986) an idea consistent with the size matching in Fig. 5, electrotonic signaling within these cells is also likely to be quite fast. It therefore seems likely that crossover inhibition primarily serves to maintain and enhance rather than to shape the basic light response.
Crossover inhibition may also serve to maintain a more constant input conductance to the cell: as the excitatory conductance increases, the inhibitory conductance decreases, and vice versa. In this way other synaptic inputs to the cell are less affected by the changes in membrane conductance of a given synapse. This process of crossover inhibition appears to be repeated at higher visual centers: similar "push pull" circuitry has been inferred at the lateral geniculate nucleus and visual cortex (Anderson et al. 2000; Hirsch 2003; Lauritzen and Miller 2003).
Functional benefits of combining rectification and crossover inhibition
The above results and analysis indicate that many synapses are rectifying, and that in many cases, throughout the inner retina, the effects of this rectification are suppressed by crossover inhibition. Stated simply, crossover inhibition acts to suppress the effects of synaptic rectification. However, the above evidence (especially in ON bipolar and ganglion cells) also indicates that synaptic rectification is not universal, and indeed, many synapses seem to behave quite linearly. This raises the question: why do many synapses in linear pathways operate in the rectifying part of the curve? Although this question is difficult to address experimentally, modeling of these synapses indicate several possible, mutually compatible benefits of rectification.
One possible answer is that a rectifying synapse has a lower level of tonic release than a synapse operating in the middle of the calcium curve. This reduced activity places less stringent requirements on the synapse in terms of energy requirements and size (a higher tonic release implies more vesicles). Although reducing synaptic release is unlikely to have a significant impact on the overall energy and size of the retina, it may provide significant local benefits in terms of metabolism.
A second likely benefit of a rectifying synapse is that it is less noisy. This has been demonstrated experimentally for the rod-bipolar synapse (Field and Rieke 2002; Rieke 2000) and seems likely to hold for other synapses. Assuming that the primary source of noise is vesicular release (and assuming this can be well described by a Poisson process), and assuming that the mean rate of release is a sigmoidal function of presynaptic voltage, rectifying synapses can be mathematically proven to provide lower noise than non-rectifying synapses (see appendix). In this context, the combination of rectification and crossover inhibition may act to maximize the dynamic range of the retina by simultaneously suppressing noise through rectification while extending the range of linear signaling through crossover inhibition.
In order to test for contrast adaptation, we provided fast periodic inputs, whose amplitude dropped by ½ partway through the simulation. In the baseline case, with both rectification and crossover inhibition (Fig. 13(b)), we see that gain adapts, decreasing for high-contrast signals, and increasing when the contrast decreases. In particular, changes in contrast cause both a reduction in amplitude and in absolute level. This absolute level shift is analogous to the "after potential" reported in (Manookin and Demb 2006). Crossover inhibition suppresses this shift in absolute level, but retains the change in amplitude. Stated differently, crossover inhibition stabilizes the baseline activity under synaptic adaptation, permitting contrast gain control without loss of information. Shifting the quiescent voltage of each model cell to the linear (non-rectifying) portion of the calcium curve eliminates contrast gain control (Fig. 13(c)): rectification allows adaptation to these slow signals. Alternately, eliminating crossover inhibition permits the variation of baseline in response to changes in contrast. As a result, more of the signal is clipped by subsequent rectification, destroying information as shown in Fig. 13(d). Thus, the model indicates that effective contrast gain control should benefit from both rectification and crossover inhibition. One prediction of this model is that eliminating crossover inhibition would increase the magnitude of after hyperpolarizations due to high-contrast signals. This prediction is born out by pharmacological results presented in (Manookin and Demb 2006).
The nervous system is but one example of how cross-subtraction between parallel, complementary signaling pathways can compensate for nonlinear circuit elements. Differential circuitry (Leibowitz et al. 2005; Razavi 2000) is one of the hallmarks of modern analog electronic circuit design. Through circuitry that is similar to that in the retina, differential circuits parse signals into a pair of complementary streams, one positive, the other its negative counterpart, and information is carried in the difference between these streams. At each stage of processing, the negative stream is subtracted from the positive stream (and vice-versa) reinforcing the differential representation of the original signal, as diagrammed in Fig. 7, and equivalent to the circuits shown in Fig. 3. This subtraction suppresses signals that are introduced in common to both streams, including artifacts from the rectifying nonlinearity inherent to their constituent transistors (Magoon et al. 2002).
This suppression is necessary partly because transistors are intrinsically nonlinear, and so always rectify their signals some degree. The degree of rectification is often enhanced however, because it is generally observed that transistors operated in their most nonlinear "subthreshold" mode provide optimal performance in terms of noise and efficiency (Steyaert and Sansen 1987). Furthermore, this mode of operation is useful for detecting signal amplitude and building variable gain circuits (Grey and Meyer 1993). Based upon our modeling, above, it seems reasonable to hypothesize that the retina gains similar benefits from rectifying synapses.
In general, differential electronic circuits are used for their greater robustness in the face of the variations, imperfections and distortions introduced by their underlying components: rather than performing explicit signal processing, differential circuits mostly act to maintain signals in the presence of various forms of interference and disruption. That crossover inhibition plays a similar, multi-functional role in the retina is supported by the work of other groups as well as our own: crossover increases ganglion cell sensitivity to low contrast signals(Manookin et al. 2008), and suppresses apparent cross-talk between the ON-and OFF systems (Renteria et al. 2006).
Crossover inhibition is not universal, however, and is distributed asymmetrically between the ON and OFF systems (as outlined in Table 1). The functional significance of this asymmetry remains a mystery, and needs additional work to be understood. For example, it may be that the asymmetry in crossover inhibition and rectification are a function of the baseline adaptation state of the retina, with ambient light driving the OFF system into a rectifying state, and that under other illumination states this would change. Regardless, the apparent correlation between rectification and crossover inhibition would seem to indicate that they are connected. One possibility is that crossover inhibition is present because it suppresses rectification. Alternately, it may be that crossover is primarily present for some other reason, but once present, it permits synaptic rectification without signal distortion, and so permits lower noise and better adaptation.
All information processing systems are intrinsically limited by the behavior of the physical components of which they are comprised. It is generally the case that efficient, low noise signaling components (transistors, synapses, axons) also show significant nonlinearity. Since such nonlinearities can distort or even destroy the information carried by the system, modern electronic circuit topologies are designed to compensate for these limitations. Crossover inhibition in the mammalian retina is an elegant example of how the topology of inhibitory circuitry in the nervous system can also overcome the limitations of its constituent neurons and synapses.
Open Access
This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited.
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Phil Davidson, CEO at Guestline
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All the Sri Lankan alumni of Indian universities and Indian Technical and Economic Cooperation (ITEC) programme are cordially invited to attend 'International Students' Day' & 'ITEC Day' being organized by the High Commission of India at 1600 hours on Friday, February 08, 2013 at Samudra Ball Room, Hotel Taj Samudra, Colombo.
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The Chapter starts out at the Finch's house. But then Atticus leaves for the legislature and it's just Jem, Scout and Calpurnia. (Dill is stuck at home in Meridian for the time being.) Since Atticus is gone, Calpurnia takes the children to her church, the First Purchase African M.E. church. The children are not immediately welcome by all members of the church, namely, Lula, who tells Cal, "You ain't got no business bringin' white chillun here—they got their church, we got our'n. It is our church, ain't it, Miss Cal?" (63). Calpurnia simply replies that it is the same God. Other members, including the Reverend Sykes, welcome them whole-heatedly.
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6 Coal Mines Shut Down Following Inspection Blitz
The six mines in question — which are owned by D&C Mining Corp., Left Fork Mining Co. Inc., Manalapan Mining Co. Inc., Conshor Mining, Red Bird Coal Co. and Cawood Enterprises LLC, respectively — received 238 citations, 55...
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Holy City Smoke Break
Summary & Our Overall Rating
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Review Details
Holy City Smoke Break
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Seasonal Spring release.


text:
Mercure Ayr Hotel, Ayr
- Free WiFi
Main amenities
- 118 smoke-free guestrooms
- Restaurant and bar/lounge
- Full-service spa
- Indoor pool
- Breakfast available
- Fitness center
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For families
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- Daily housekeeping
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- Coffee/tea maker
- Elevator/lift
What's around
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- Classic Room, 2 Twin Beds
- Classic Room, 1 Double Bed
- Standard Single Room, 1 Twin Bed
- Standard Room, 1 Double Bed (Compact)
More great choices
At a glance
Key facts
Hotel size
- This hotel has 118 rooms
- This hotel is arranged over 8 floors
- Check-in time starts at 2 PM
- Check-out time is noon
- Express check-in/out
Required at check in
- Credit card or cash deposit required
- Government-issued photo ID required
Travelling with others
- No cribs (infant beds)
- Pets not allowed
- Free WiFi in public areas
- Free WiFi in rooms
- Self parking *
Other information
- Smoke-free property
In the hotel
- Buffet breakfast daily (surcharge)
- Restaurant
- Bar/lounge
- Room service (during limited hours)
- Indoor pool
- Fitness facilities
- Full-service spa
- Steam room
- Golfing nearby
- Sauna
- Meeting rooms 7
- 24-hour front desk
- Dry cleaning/laundry service
- Laundry facilities
- Free newspapers in lobby
- Number of buildings/towers - 1
- Year Built 1972
- Elevator/lift
- Safe-deposit box at front desk
- Accessible bathroom
- In-room accessibility
- Roll-in shower
In the room
- In-room climate control (air conditioning)
- Air conditioning
- Coffee/tea maker
- Iron/ironing board (on request)
- Private bathroom
- Bathtub or shower
- Flat-screen TV
- Digital TV channels
- Desk
- Free WiFi
- Phone
- Daily housekeeping
- In-room safe
- Connecting/adjoining rooms available
Also popular with travelers from the USA
Special features
Guests can indulge in a pampering treatment at the hotel's full-service spa. Services include hot stone massages, sports massages, Swedish massages, and massages. The spa is equipped with a sauna, a spa tub, and a steam room.
The spa is open daily. Children under 16 years old are not allowed in the spa without adult supervision.
Mercure Ayr Hotel, Ayr's small print
Also known as
- Ayr Mercure
- Ayr Mercure Hotel
- Hotel Mercure Ayr
- Mercure Ayr
- Mercure Ayr Hotel
- Mercure Hotel Ayr
- Ayr Ramada
- Mercure Ayr Hotel Scotland
- Ramada Ayr
The property has connecting/adjoining rooms, which are subject to availability and can be requested by contacting the property using the number on the booking confirmation.
Children under 16 years old are not allowed in the spa without adult supervision.
Optional extras
Self parking costs GBP 3.00 per day
Buffet breakfast is offered for an extra charge of GBP 13.95 per person (approximately)
We have included all charges provided to us by this hotel. However, charges can vary, for example, based on length of stay or the room you book.
What's around Mercure Ayr Hotel, Ayr
- Wellington Square (3-minute walk)
- Auld Kirk (5-minute walk)
- Pirate Pete's Family Entertainment Centre (6-minute walk)
- Ayr Pavilion (6-minute walk)
- Ayr Town Hall (6-minute walk)
- Auld Brig (7-minute walk)
- Ayr Beach (14-minute walk)
- Ayr Racecourse (14-minute walk)
Getting around
- Glasgow (PIK-Prestwick) 13-min drive
- Glasgow (GLA-Glasgow Intl.) 55-min drive
- Ayr Station 10-min walk
- Newton-on-Ayr Station 22-min walk
- Prestwick Town Station 13-min drive
- Self parking (surcharge)
Is the description of this hotel not correct? Tell us


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first edition Hardcover
1950 · London
by Hammond, Alex
London: Arthur Barker Ltd., 1950. Book. Very good+ condition. Hardcover. First Edition. Octavo (8vo). 160 pages of text. Hardcover binding with minor browing along the edges. The unclipped dustjacket is heavily sunned on the spine, with numerous chips and tears; protected in archival mylar. Illustrated with 61 plates, many of which have more than one image. The text is clean and unmarked. First edition.. (Inventory #: 017204)


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How would you describe a perfect winter's day? One might think that there's no better way to keep the chill out than snuggling up in a blanket with all your loved ones surrounding you.
But how about snuggling with your family inside your cosy home AND sipping a warm bowl of soup? Now that's a perfect way to pass the time during winter. Store your soups for in our TM Essentials 600ml Thermos for packed lunches - available here.
Here's a list of our top 10 Thermomix soups that'll keep your belly full and happy during winter. Have fun cooking!
1.Roasted Pumpkin, Garlic, and Sage Soup
Photo credit: tenina.com
Nothing feels more winter-y than pumpkins! Make this pumpkin soup recipe from tenina.com. Add some sage leaves and garlic to this soup to create that exceptional aromatic flavour. This dish can warm you up during your hiking trip. To make sure that the soup won't spill in your bag and it stays hot for a long period of time, you can store it in a Wide Neck Steel Thermos from TM Essentials.
2.Chicken and Corn Soup
Photo credit: mykitchencounter.com
For a more traditional flavour, you can never go wrong with Chicken and Corn soup. This recipe from thermomixin.com is very easy to make and only needs a few ingredients. However, it has a creamy texture and slightly sweet taste that can brighten up your day!
3.Creamy Bacon and Vegetable Soup
Photo credit: quirkycooking.com.au
This is a soup that's perfect for picky eaters. It can easily be done with some left over bacon and veggies. The recipe from quirkycooking.com.au can be used as a perfect appetizer for fish or meat dishes!
4.Skinnymixer's No Fat Tomato Soup
Photo credit: skinnymixers.com.au
Don't know what to do with those extra tomatoes? Make some healthy tomato soup! This recipe from skinnymixers.com.au will keep your family warm and full this winter, without worrying too much about gaining extra weight.
5.Cauliflower, Pancetta, and Lentil Soup
Photo credit: kevskitchen.com
You may not be able to visit Italy, but you can still enjoy an authentic Italian dish by trying this recipe from alycealexandra.com. Creamy cauliflower, salty pancetta, and yummy lentil in a warm soup? Delizioso! Host a fancy dinner party with your family by preparing other classic meals such as vegetable lasagne roll ups or spinach & cheese manicotti.
6.Barley and Autumn Vegetable Soup
Photo credit: foodfilanderer.wordpress.com
This recipe from foodfilanderer.wordpress.com will keep your family energized because of its veggie and barley ingredients. A fulfilling and hearty meal for the cold months ahead!
7.Sweet Potato, Lime, and Coconut Soup
Photo credit: bakeplaysmile.com
If you love to add sweet coconut milk in your dishes, then this recipe should be added to your menu! Bakeplaysmile.com's soup is sweet, creamy, slightly tangy, and absolutely delicious, thanks to the combination of coconut milk, veggies, and spices.
8.Cream of Mushroom Soup Recipe
Photo credit: seanasmith.com
Just like the Chicken and Corn soup, Cream of Mushroom is traditional, but nonetheless tasty and fulfilling dish. The recipe from seanasmith.com is quick to prepare, especially if you have your Thermomix!
9.Rockpool's Cream of Cauliflower Soup with Parmesan
Photo credit: gastronomy.com
For a simpler cauliflower soup, this recipe from gastronomy.com will keep your family happy for the rest of the winter! The Parmesan just adds that dash of saltiness that you can never get enough of!
10.Green Power Soup
Photo credit: foodforthought.com.au
If you (and if you can convince your family) want a taste of some Kale soup this winter, then you can try this recipe from foodforthought.com.au. Kale offers a surplus of Vitamin A, K, C, B6, Manganese, Calcium, and many more.
Create a scrumptious meal within minutes! Keep the cold out this winter while keeping yourself and your family's tummy warm and full.
Grab your TM Essentials Thermos for storing your soup here.


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When you dress in relatively outrageous attire on a regular basis, a day like Halloween is like a breather. It's a bit of a relief to see everyone else finally put as much care and concern into making an impression as I try to do on a daily basis. For that reason, I usually sit Halloween out – or if I do go to a party or event, I tend to be considerably subtle about it. (A hooded cape is the most you'll usually get out of me.)
For those who want a bit more, here's a sampling of what I wear throughout the year. These are various get-ups for holiday cards, grocery shopping, work, and the day-to-day hum-drum existence of a casual blogger. This is why I'll be in sweats and a t-shirt today.
PS – Don't even think about ringing my doorbell.Back to Blog


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EDITORIAL: SkinheadCyril Trehoux is snapped by Milan Vukmirovic for the third issue of Fashion for Men, donning hard-edged designs from Jean Paul Gaultier, Boris Bidjan Saberi and more.
hommemodel 12:00 PM Cyril Trehoux
© HommeModel - The Premier Source for Menswear in High Quality 2014 . Powered by Blogger . Blogger templates


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We use cookies to ensure that we give you the best experience on our page. If you continue we assume that you consent to receive all cookies on our website. Read more here.
We bring Scandinavian Design to you
Monday - Friday: 8:00 - 16.00 (CET)
The small Collect lamp is part of the Collect collection by Ferm Living. The smart collection lets you put your lamp together by yourself by combining lamp base with whichever lamp shade you wish to combine it with. This particular base has a simple cylindrical shape with a decorative brass ring, ceiling cup and textile cord. When not combined with a lamp shade, the Collect ceiling lamp small is perfect for adding a minimalistic and slightly industrial feel to your home.
Ferm Living
Ferm Living


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The most lawless town in the West is about to get some justice in this novel in the USA Today bestselling Ralph Compton series…
After ten years of working his way across the West, Cas Everett returned to his family's farm in Texas only to find a charred ruin that was once his home—and five grave markers representing his parents and siblings. Their deaths were not accidental.
Cas's time as a bounty hunter has earned him notoriety as a quick-draw artist and… (more)
Publisher: Berkley (November 07, 2006)
Format: EPUB
Page count: 304 pages
File size: 291 KB
Protection: DRM
Language: English


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DIRECTOR'S ELECTED DURING SAMIC's AGM
It is with great pleasure to announce that the Roll Players of the Red Meat Industry Forum has elected during SAMIC's Annual General Meeting, held on the 24th August 2016, two independent non executive directors to serve on the SAMIC Board of Directors, with the current Executive Director, Mr Rudi van der Westhuizen.
Advocate Les Kugel, an independent business man called 'Kugel Legal', will be responsible for all SAMIC's legal actions, and
Mr JM (Boet) Venter, previous retired CEO of SAMIC, which have vast financial experience will be responsible for SAMIC's financial function. Mr Venter is also the Chairman of the Board of Directors.
Mr Rudi van der Westhuizen will still be responsible for SAMIC's day to day functions.
The South African Meat Industry Company (SAMIC) being appointed as assignee, in terms of section 2(3) of the Agricultural Product Standards Act, 1990 (Act No. 119 of 1990), by Government Notice No. 121 of 1998 for the classification and marking of meat, hereby impose the following service fee in respect of abattoirs that participate in the classification and marking of meat (No. R. 55 of 30 January 2015). These service fees will be valid from 1 January 2017.
|Abattoir Grade
|Service fee / Month (VAT excluded)
|High Throughput
|Low Throughput
Legal appointment for independent 3rd party Service Providers
For all Red Meat Abattoirs who voluntary make use of the Red Meat Classification system.
Please take note that SAMIC has appointed the following 3rd Party Service Providers to deliver only meat classification services and were necessary meat inspection services and no other abattoir services.;
Mr Gerrie Oberholzer
Tel: 083 625 5462
E-mail: firstname.lastname@example.com
Mr Rassie Smit
Tel: 084 712 6717
E-mail: email@example.com
Gauteng Meat Inspection Services
Mr Francois Pretorius
Tel: 082 375 3114
E-mail: firstname.lastname@example.com
Zero Plus Services
Mr C Oberholzer
Tel: 072 154 8341
E-mail: email@example.com
Mr B Mazengera
Tel: 083 295 6306
E-mail: email@example.com
Mr G von Wiellich
Tel: 082 222 0333
E-mail: firstname.lastname@example.com
Mr RR Singleton
Tel : 082 708 4699
E-mail : email@example.com
Hlonza & Ngobza Projects
Mr TL Ngobeni
Mr YS Hlongwane
Any new registration in this regard will be published for your attention.
Ensuring that you are using a registered 3rd party Independent Service Provider remains the responsibility of the Abattoir owner.
Implementation date for the appointment of registered 3rd party independent meat classification service providers by abattoirs is 1 August 2015


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It never ceases to amaze me why the same people who through my tax dollars want me to pay for their educational choice, via PYP and IB, but do not want to pay for teaching Creation Science, my educational choice for my kids. They say those of us who want our kids taught Creation Science can send them to a private religious school.
I am reasonably sure there are some private schools that teach PYP and IB. If not, there is always the choice of home schooling.
If the supporters of PYP and IB schools of choice truly wanted education choice they would support an educational voucher program. Then all parents would have equal opportunity to choose where and how they want to educate their children. They could decide whether to send their kids to public, private secular, religious, charter, or they could even home school them.
This plan should put an end to people forcing their educational philosophy on their neighbors� kids.
Coeur d�Alene


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Wedding Minister in and around Milan, New Mexico.
Life's Moments are those times in life that we choose to make a special acknowledgment of life changing events. Weddings are celebrations, weddings are events, but most importantly weddings are a new beginning, a moment in time to be treasured. Having the best Minister is very important.
For these moments, we provide extensive Wedding Minister services, Scottish Wedding officiating, and also wedding services. From the very conventional to contemporary solutions, our wedding events as well as officiating solutions are developed to mirror your desires, wishes and also desires. We will help you to craft an event, secular or spiritual that will be a treasured memory for many years to come.
Ministerial services and also wedding celebration officiating in the Milan, New Mexico location is our specialty, but we could travel if the need occurs. We offer a complete array of Scottish Wedding plans; from elopement on the courthouse steps to one of the most intricate formal wedding you might want.
We also offer the finest in Justice of the Peace or secular weddings. These civil ceremonies provide their very own form of celebration, whether it be with family members or just a couple as well as a couple of witnesses, your wedding celebration is a special moment to be valued.


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The Pittsburgh Riverhounds have bolstered their defense again.
The club announced that they have received defender Shannon Gomez on loan from New York City FC. The Riverhounds and New York City FC have agreed to have Gomez stay in Pittsburgh for the rest of the 2017 season.
However, since Gomez is part of the MLS' USL Loan Agreement, he can return to New York City anytime during the season and feature for both clubs.
The boost on defense is needed, as Joe Greenspan's loan has been up for the Riverhounds, and Shane Campbell still remains sidelined with injury. Rich Balchan suffered an ACL injury back in April, and is out for the rest of the season.
In addition, Ryan Adeleye has yet to compete in a match this season, but has returned to the practice pitch. Also, Ritchie Duffie has also been out for the Riverhounds since the Louisville City FC match.
"This was an opportunity for us to acquire a really sharp, quick, experienced young player from a top organization like New York City FC," Riverhounds head coach Dave Brandt said. "We've obviously dealt with some injuries in the back and having a young, talented player like Shannon, who can play right back, will help us moving forward this season."
Gomez, who is from Trinidad & Tobago, started his career with W Connection F.C. in the TT Pro League.
In 2016, Gomez was a Discovery Signing on loan for New York City FC. However, during the offseason, he signed his first professional contract. To this day, he has not appeared in a match yet this season, and only dressed for a match once.
In 2015, Gomez made his national team debut for Trinidad & Tobago. He has two appearances under his belt for The Soca Warriors.
Gomez and the Riverhounds will host the Charlotte Independence on Tuesday for their annual Fourth of July match. Tickets are still available, with kickoff time expected at 7 p.m.
Follow @RachaelMcKriger on Twitter for all Riverhounds coverage.


text: There is a plastic retaining clip that holds the actuator rod from the plunger to the lock that is broken. The fix? Well, I actually zip tie it back in place. I have fixed 2 locks this way and 2 using the replacement part. Guess what? The replacement part broke. My zip strip fix is still holding years later. Shayne P. 1972 MB 280 SEL 4.5 1984 4ksq 1986 MB 560 SEL 1991 v8q5 1991 200q Sedan 1992 S4 Parting: 1972 Mercedes Benz 280 SE 4.5 > From: G Johnson <gregsj2 at attbi.com> > Date: Tue, 04 Dec 2001 22:08:59 -0800 > To: 200 List <200q20v at audifans.com>, QList <quattro at audifans.com> > Subject: [200q20v] Driver's door lock > > Fellow Audians, > > My driver's door lock has been a bit odd the past few days. Mostly > sticking. I figured it was the cold/snow. > > Came out of nail biter, overtime, Gonzaga BB game tonight and the lock > suddenly felt very smooth. Turned out to be too smooth. > It goes back and forth, and while I hear the alarm beep, the door would > not unlock. Luckily, I was able to get in from the other side. > > Any ideas? > > How much $$$. > > Greg J > > _______________________________________________ > 200q20v mailing list > 200q20v at audifans.com > http://www.audifans.com/mailman/listinfo/200q20v _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com


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Universal Monsters Universe turns 1!
Universal Monsters Universe turns one! It's an anniversary, or as we're calling it, a MONSTER-VERSARY, and that's very special for all of us at Team UMU. In the past few weeks we've seen more followers, visitors, and monster heads show their support and love for us and the iconic monsters that make this all possible. To all of you, we say thank you! For those that have been following since early February 2016, we hope you've enjoyed the content we produce and we hope that you continually join us as we grow closer to the June 2017 start of the "new world of gods and monsters," with the release of The Mummy.
One of the most enduring and iconic of film franchises is the Universal Monsters movies of the 1920's to 1950's. Classic, beloved, and frightening, the affect of the Universal Monsters can be seen in almost all forms of pop-culture – movies, comic books, collectibles, and so much more.
Even though the Universal Monsters movies were considered scary or even horror at the time they were released, it can be said they had a tragic romantic quality to them. The Universal Monsters films are timeless and, well, universal. The themes and qualities that made these pictures so successful back when they were released are still relatable to this day. As executive producer and Monsters Universe creative architect, Chris Morgan, said, "We're exploring issues of family identity and questions of, 'Where do I belong in the world?'" It's these very themes that we're excited to see come alive on screen in this June's The Mummy and future Universal Monsters films. In the same sense that the monsters were always just there for me, I hope a new generation enjoys these pictures as much as I did and still do.
As you all know, this is a major year for classic monsters with the return of King Kong and The Mummy. Kong: Skull Island opens March 10th and The Mummy is awakened on June 9th. While you will find traces of the monsters of Skull Island here on UMU, you could expect us to continually push the lid off of the sarcophagus as we grow closer to The Mummy. This is Universal Monsters Universe and we could not be more excited to continually provide coverage on the upcoming Alex Kurtzman directed film that is set to launch a new, updated take on the classic monsters that we all love. We've had the pleasure of covering The Mummy since pre-production and all throughout principal photography. And while coverage of the "inside look" and theatrical trailer of The Mummy may have been lost during our relaunch, you could certainly expect to find us taking another look at a film we are counting down the days to see.
This is "Universal Monsters Universe," your destination into adventure and the macabre; your #1 spot for the latest on the Universal Monsters Universe of films old and new (and some other monster stuff too!). We had envisioned this site as a go-to hub for all things classic monsters. We wanted to be able to carry on the tradition of people whose love and respect for the Universal Monsters have carried them across the generations and be able to elevate the next iteration of those classic tales, starting with The Mummy. We're excited to see what this new world of Gods and Monsters will bring and we hope that you'll help us continue to keep the thrills and chills of the classics alive.
In the cadence of Bela Lugosi, we bid you welcome.
Suggestions, comments, concerns? Want to contribute? Maybe have a tip? Want to talk and raise the dead? Contact us at:
Universal Monsters Universe could also be found on:
Facebook, Twitter, Instagram, and Tumblr.


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Ham and Swiss Quiche is perfect for an Easter brunch! Quiche is easy to prepare ahead of time which makes it a good choice for reheating after Easter Sunday church services. It's not too heavy, but hearty enough to be the main dish. You can serve Ham and Swiss Quiche alongside a fresh fruit salad and blueberry muffins for a complete Easter brunch meal!
- 1 9-inch pie shell
- 1 ½ cups chopped Petit Jean Smoked Ham
- 1¼ cups freshly grated Swiss cheese (fresh vs prepackaged makes a big difference in flavor)
- ¼ t. dried basil
- ¼ t. salt
- 5 eggs, beaten
- 1 cup skim milk (for richer quiche, use whole milk or half and half)
- sprinkle of dry mustard
- Preheat oven to 350°.
- Mix all ingredients in a bowl and pour into pie crust.
- Place quiche onto a cookie sheet to collect any spills while baking.
- Bake at 350° for 50 minutes to one hour or until top is light brown.
Amanda is a blogger and writer at www.AmandaJaneBrown.com and shares affordable and simple seasonal décor, everyday recipes, and family traditions. After living in Arkansas for 10 years, Amanda now lives in Oxford, Mississippi with her husband and three children.
Amanda is a member of the Petit Jean Meats Blue Diamond Club. A group of dedicated ambassadors who share their love of Petit Jean Meats with the world.


text: I would encourage young players to NOT employ the services of a manager to negotiate a contract, and use their fee in another way. I would love to see something like this happen.... Each club has an internal person employed to help players come to a contract agreement. The agreement is as simplistic and transparent as possible so all parties can easily understand all that is required to see the contract through. In our case, I'd like to see Kingy given the role once he hangs up the boots. I'm not sure which direction his Law expertise takes, but a simple contract agreement is probably within his capabilities. It would be great to keep him at the club after he retires. His role could expand into helping players with 3rd party deals. Say a player, for arguments sake, DCE wants to play for Manly and Manly wants him here. Now, lets say he agrees to $400k per year. A manager may take 10% of that as his fee. Rather than pay this $40k to a manager....imagine if the player actually gave it back to the club to invest in a younger player. If we could use that $40k to invest the time etc into a young bloke, and keep him at the club, we are investing in our future. Imagine a whole team willing to dice their managers and reinvest their managers cut back into the club! A small % from each players 10% could also go towards paying the salary for the newly created role for Kingy. The salary cap would still stand and be adhered to. Nothing changes there. The players would be losing nothing. They would still be on the same money they would have been getting anyway. Managers would not be there to manipulate the media and create tensions between players by "leaking" stories to try and bolster their own income. The club would be financially better off and have more chance of keeping young talent here. The players are happy, the clubs are happy, the young talent is happy so the fans would be happy which in turn should make the NRL happy. Well, it'll never happen I guess so it doesn't matter....but jeez I'd love to know if it would be possible, and if so, I'd love Manly to be the team to adopt it first.


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Back in college, a few friends and I would get together for competitive games of the racing game Rush. It was a good way to kill a few minutes before going to the cafeteria or before a frat party. Invariably, the game would also be there when we got home from the frats and yes, trying to race in a video game while intoxicated is a great way to learn that one can't and definitely shouldn't attempt to drive drunk for realzies. Also? When you die in the video game you can just put more quarters in. Not so much in real life.
Basically, that cautionary tale is just preamble to say that "the Octane 120 Pro Beer Arcade From Dream Arcades is a home machine designed for driving simulators that includes a built-in kegerator and two taps, one in the trunk and one in the dash. The one in the dash sits above a cupholder too SO YOU CAN POUR BETWEEN TURNS." This is such a steal for $6000 because it comes with 12 classic driving games. Plus? Beer. Oh. And? Yeah, this is pretty much what I'd buy if I were Tom Hanks in Big.


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