Synchrony between orientation-selective neurons is modulated during adaptation-induced plasticity in cat visual cortex

Background  

Visual neurons respond essentially to luminance variations occurring within their receptive fields. In primary visual cortex, each neuron is a filter for stimulus features such as orientation, motion direction and velocity, with the appropriate combination of features eliciting maximal firing rate. Temporal correlation of spike trains was proposed as a potential code for linking the neuronal responses evoked by various features of a same object. In the present study, synchrony strength was measured between cells following an adaptation protocol (prolonged exposure to a non-preferred stimulus) which induce plasticity of neurons' orientation preference.     

Formulas for the Inverses of Toeplitz Matrices with Polynomially Singular Symbols

We consider large finite Toeplitz matrices with symbols of the form (1– cos )^p f() where p is a natural number and f is a sufficiently smooth positive function. By employing techniques based on the use of predictor polynomials, we derive exact and asymptotic formulas for the entries of the inverses of these matrices. We show in particular that asymptotically the inverse matrix mimics the Green kernel of a boundary value problem for the differential operator Submitted: June 20, 2003     

Résolution des équations de dispersion–diffusion en présence de forts gradientsResolution of advection–diffusion equation in presence of sharp gradient

In order to resolve the convection terms in the simulation of coastal flows, we propose a numerical method based on the Total Variation Diminishing scheme completed with the Artificial Compression Method to reduce the artificial diffusion and to sharpen the tracer profile in strong gradient regions. This method was applied successfully at discontinuous regions, but out of these regions a limitation of its application is necessary. An application is made to estimate the width of the fresh water band in the Eastern English Channel. To cite this article: C. Sart et al., C. R. Mecanique 330 (2002) 159–165.     

Isoscalar NN spin-orbit potential from a Skyrme model with scalar mesons

As a first step toward circumventing the difficulty to obtain an attractive isospin-independent NN spin-orbit force from Skyrme-type models involving only pions, we investigate an improved Skyrme Lagrangian that incorporates the scalar-isoscalar meson ε which can be viewed as the cause behind the enhancement of the ππ S-wave. We find that at large distances, the main contribution to the spin-orbit potential comes from the scalar Lagrangian and it is found to be attractive. We briefly discuss how to pursue this work to finally obtain a medium-range attractive interaction.     

Direct and indirect electrochemical oxidation of Indigo Carmine using PbO2 and TiRuSnO2

Journal of Solid State Electrochemistry - In this paper, the electrocatalytic properties of PbO2 and TiRuSnO2 anodes for direct and indirect electrochemical oxidation of a synthetic solution...     

Hyperstability of the Jensen functional equation in ultrametric spaces

In this paper, we present hyperstability results of Jensen functional equations in ultrametric Banach spaces.     

New procedure calculation of K-shell ionization cross sections by proton impact

The database, which relies on different compilations available in the literature and on other experimental values extracted from papers published from 1992 till 2010, is used, within the individual treatment of the elements from beryllium (⁴Be) to uranium (⁹²U), to deduce the empirical cross sections. These experimental data can be presented in a single curve, depending on a scaling law extracted from studies in the most familiar theories of collision (PWBA and BEA). Then, a fourth order polynomial was used to fit very well the existing database of K-shell ionization cross sections by proton. This procedure generates a new set of parameters to calculate empirical cross sections. Following the present procedure, our results are compared with those obtained using the ECPSSR model where a discrepancy is observed in the low-proton energy regime.     

Synthesis, microwave spectrum, and dipole moment of allenylisocyanide (H2C═C═CHNC), a compound of potential astrochemical interest

An improved synthesis of a compound of potential astrochemical interest, allenylisocyanide (H(2)C═C═CHNC), is reported together with its microwave spectrum, which has been investigated in the 8-120 GHz spectral range to facilitate a potential identification in interstellar space. The spectra of the ground vibrational state and of five vibrationally excited states belonging to three different vibrational modes have been assigned for the parent species. A total of 658 transitions with a maximum value of J = 71 were assigned for the ground state and accurate values obtained for the rotational and quartic centrifugal distortion constants. The spectra of five heavy-atom ((13)C and (15)N) isotopologues were also assigned. The dipole moment was determined to be μ(a) = 11.93(16) × 10(-30) C m, μ(b) = 4.393(44) × 10(-30) C m, and μ(tot) = 12.71(16) × 10(-30) C m. The spectroscopic work has been augmented by theoretical calculations at the CCSD/cc-pVTZ and B3LYP/cc-pVTZ levels of theory. The theoretical calculations are generally in good agreement with the experimental results.     

Influence of anions on the dimensionality of extended networks based on Cu I cations and 1,4,5,8,9,12-hexaazatriphenylene (HAT) ligands

Reactions of Cu I salts with 1,4,5,8,9,12-hexaazatriphenylene (HAT) afford three types of cationic coordination polymers depending on the anion present in the reaction solution. In the crystal structure of {[Cu(HAT)][BF4]x1/3(C6H6)}infinity, (1), Cu ions and HAT molecules form extended layers that are best described as strongly distorted honeycomb nets. The space between the layers is occupied by [BF4]- anions and solvent molecules. {[Cu(HAT)][PF6]}infinity, (2), crystallizes as a chiral (10,3)-a net with [PF6]- anions residing in the cavities of the three-dimensional metal-organic framework. The crystal structure of {[Cu4(HAT)3][SbF6]4x3C6H6}infinity, (3), is based on unique extended [Cu4(HAT)3]infinity "nanotubules" filled with solvent molecules and [SbF6]- anions.