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J. Comp (j + comp)
Selected AbstractsSynaptic contacts between an identified type of ON cone bipolar cell and ganglion cells in the mouse retinaEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 5 2005Bin Lin Abstract We surveyed the potential contacts between an identified type of bipolar cell and retinal ganglion cells in the mouse. By crossing two existing mouse strains (line 357 and line GFP-M), we created a double transgenic strain in which GFP is expressed by all members of a single type of ON cone bipolar cell and a sparse, mixed population of retinal ganglion cells. The GFP-expressing bipolar cells appear to be those termed CB4a of Pignatelli & Strettoi [(2004) J. Comp. Neurol., 476, 254,266] and type 7 of Ghosh et al. [(2004) J. Comp. Neurol., 469, 70,82 and J. Comp. Neurol., 476, 202,203]. The labelled ganglion cells include examples of most or all types of ganglion cells present in the mouse. By studying the juxtaposition of their processes in three dimensions, we could learn which ganglion cell types are potential synaptic targets of the line 357 bipolar cell. Of 12 ganglion cell types observed, 10 types could be definitively ruled out as major synaptic targets of the line 357 bipolar cells. One type of monostratified ganglion cell and one bistratified cell tightly cofasciculate with axon terminals of the line 357 bipolar cells. Double labelling for kinesin II demonstrates colocalization of bipolar cell ribbons at the sites of contact between these two types of ganglion cell and the line 357 bipolar cells. [source] A combination of implicit and adaptative upwind tools for the numerical solution of incompressible free surface flowsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 6 2007V. G. Ferreira Abstract This paper is concerned with the numerical solutions of time dependent two-dimensional incompressible flows. By using the primitive variables of velocity and pressure, the Navier,Stokes and mass conservation equations are solved by a semi-implicit finite difference projection method. A new bounded higher order upwind convection scheme is employed to deal with the non-linear (advective) terms. The procedure is an adaptation of the GENSMAC (J. Comput. Phys. 1994; 110:171,186) methodology for calculating confined and free surface fluid flows at both low and high Reynolds numbers. The calculations were performed by using the 2D version of the Freeflow simulation system (J. Comp. Visual. Science 2000; 2:199,210). In order to demonstrate the capabilities of the numerical method, various test cases are presented. These are the fully developed flow in a channel, the flow over a backward facing step, the die-swell problem, the broken dam flow, and an impinging jet onto a flat plate. The numerical results compare favourably with the experimental data and the analytical solutions. Copyright © 2006 John Wiley & Sons, Ltd. [source] Performance of very-high-order upwind schemes for DNS of compressible wall-turbulenceINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 7 2010G. A. Gerolymos Abstract The purpose of the present paper is to evaluate very-high-order upwind schemes for the direct numerical simulation (DNS) of compressible wall-turbulence. We study upwind-biased (UW) and weighted essentially nonoscillatory (WENO) schemes of increasingly higher order-of-accuracy (J. Comp. Phys. 2000; 160:405,452), extended up to WENO17 (AIAA Paper 2009-1612, 2009). Analysis of the advection,diffusion equation, both as ,x,0 (consistency), and for fixed finite cell-Reynolds-number Re,x (grid-resolution), indicates that the very-high-order upwind schemes have satisfactory resolution in terms of points-per-wavelength (PPW). Computational results for compressible channel flow (Re,[180, 230]; M,CL,[0.35, 1.5]) are examined to assess the influence of the spatial order of accuracy and the computational grid-resolution on predicted turbulence statistics, by comparison with existing compressible and incompressible DNS databases. Despite the use of baseline O(,t2) time-integration and O(,x2) discretization of the viscous terms, comparative studies of various orders-of-accuracy for the convective terms demonstrate that very-high-order upwind schemes can reproduce all the DNS details obtained by pseudospectral schemes, on computational grids of only slightly higher density. Copyright © 2009 John Wiley & Sons, Ltd. [source] Adaptive approach for nonlinear sensitivity analysis of reaction kineticsJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 9 2005Illia Horenko Abstract We present a unified approach for linear and nonlinear sensitivity analysis for models of reaction kinetics that are stated in terms of systems of ordinary differential equations (ODEs). The approach is based on the reformulation of the ODE problem as a density transport problem described by a Fokker,Planck equation. The resulting multidimensional partial differential equation is herein solved by extending the TRAIL algorithm originally introduced by Horenko and Weiser in the context of molecular dynamics (J. Comp. Chem. 2003, 24, 1921) and discussed it in comparison with Monte Carlo techniques. The extended TRAIL approach is fully adaptive and easily allows to study the influence of nonlinear dynamical effects. We illustrate the scheme in application to an enzyme-substrate model problem for sensitivity analysis w.r.t. to initial concentrations and parameter values. © 2005 Wiley Periodicals, Inc. J Comput Chem 26: 941,948, 2005 [source] Cytoarchitectonic and chemoarchitectonic subdivisions of the perirhinal and parahippocampal cortices in macaque monkeysTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 6 2007Kadharbatcha S. Saleem Abstract Although the perirhinal and parahippocampal cortices have been shown to be critically involved in memory processing, the boundaries and extent of these areas have been controversial. To produce a more objective and reproducible description, the architectonic boundaries and structure of the perirhinal (areas 35 and 36) and parahippocampal (areas TF and TH) cortices were analyzed in three macaque species, with four different staining methods [Nissl and immunohistochemistry for parvalbumin, nonphosphorylated neurofilaments (with SMI-32), and the m2 muscarinic acetylcholine receptor]. We further correlated the architectonic boundary of the parahippocampal cortex with connections to and from different subregions of anterior area TE and with previously published connections with the prefrontal cortex and temporal pole (Kondo et al. [2005] J. Comp. Neurol. 493:479,509). Together, these data provided a clear delineation of the perirhinal and parahippocampal areas, although it differs from previous descriptions. In particular, we did not extend the perirhinal cortex into the temporal pole, and the lateral boundaries of areas 36 and TF with area TE were placed more medially than in other studies. The lateral boundary of area TF in Macaca fuscata was located more laterally than in Macaca fascicularis or Macaca mulatta, although there was no difference in architectonic structure. We recognized a caudal, granular part of the parahippocampal cortex that we termed "area TFO." This area closely resembles the laterally adjacent area TE and the caudally adjacent area V4 but is clearly different from the more rostral area TF. These areas are likely to have distinct functions. J. Comp. Neurol. 500:973,1006, 2007. © 2006 Wiley-Liss, Inc. [source] Synaptic organization of complex ganglion cells in rabbit retina: Type and arrangement of inputs to directionally selective and local-edge-detector cellsTHE JOURNAL OF COMPARATIVE NEUROLOGY, Issue 4 2005Edward V. Famiglietti Abstract The type and topographic distribution of synaptic inputs to a directionally selective (DS) rabbit retinal ganglion cell (GC) were examined and were compared with those received by two other complex GC types. The percentage of cone bipolar cell (BC) input, presumably an index of sustained responses and simple receptive field properties, is much higher than expected for complex GCs in reference to previous reports in other species: approximately 20% for the type 1 bistratified ON,OFF DS GC and for a multistratified GC, and approximately 40% for the small-tufted local-edge-detector GC. Consistent with a previous study (Famiglietti [1991] J. Comp. Neurol. 309:40,70), no ultrastructural evidence is found for inhibitory synapses from starburst amacrine cells to the ON,OFF DS GC. The density of inputs to the ON,OFF DS GC is high and rather evenly distributed over the dendritic tree. Clustering of inputs brings excitatory and inhibitory inputs into proximity, but the strict on-path condition of more proximal inhibitory inputs, favoring shunting inhibition, is not satisfied. Prominent BC input and its regional variation suggest that BCs play key roles in DS neural circuitry, both pre- and postsynaptic to the ON,OFF DS GC, according to a bilayer model (Famiglietti [1993] Invest. Ophthalmol. Vis. Sci. 34:S985). Asymmetry of inhibitory amacrine cell input may signify a region on the preferred side of the receptive field, the inhibition-free zone (Barlow and Levick [1965] J. Physiol. (Lond.) 178:477,504), supporting a role for postsynaptic integration in the DS mechanism. Prominent BC input to the local-edge-detector, often without accompanying amacrine cell input, indicates presynaptic integration in forming its trigger feature. J. Comp. Neurol. 484:357,391, 2005. © 2005 Wiley-Liss, Inc. [source] | |||||||||||||