Random perturbations of spiking activity in a pair of coupled neurons

We examine the effects of stochastic input currents on the firing behaviour of two coupled Type 1 or Type 2 neurons. In Hodgkin–Huxley model neurons with standard parameters, which are Type 2, in the bistable regime, synaptic transmission can initiate oscillatory joint spiking, but white noise can terminate it. In Type 1 cells (models), typified by a quadratic integrate and fire model, synaptic coupling can cause oscillatory behaviour in excitatory cells, but Gaussian white noise can again terminate it. We locally determine an approximate basin of attraction, \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\mathcal{A}}},$$\end{document} of the periodic orbit and explain the firing behaviour in terms of the effects of noise on the probability of escape of trajectories from \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${{\mathcal{A}}}.$$\end{document

Large-Aperture Membrane Active Phased-Array Antennas

Large-aperture phased-array microwave antennas supported by membranes are being developed for use in spaceborne interferometric synthetic aperture radar systems. There may also be terrestrial uses for such antennas supported on stationary membranes, large balloons, and blimps. These antennas are expected to have areal mass densities of about 2 kg/sq m, satisfying a need for lightweight alternatives to conventional rigid phased-array antennas, which have typical areal mass densities between 8 and 15 kg/sq m. The differences in areal mass densities translate to substantial differences in total mass in contemplated applications involving aperture areas as large as 400 sq m. A membrane phased-array antenna includes patch antenna elements in a repeating pattern. All previously reported membrane antennas were passive antennas; this is the first active membrane antenna that includes transmitting/receiving (T/R) electronic circuits as integral parts. Other integral parts of the antenna include a network of radio-frequency (RF) feed lines (more specifically, a corporate feed network) and of bias and control lines, all in the form of flexible copper strip conductors on flexible polymeric membranes. Each unit cell of a prototype antenna (see Figure 1) contains a patch antenna element and a compact T/R module that is compatible with flexible membrane circuitry. There are two membrane layers separated by a 12.7-mm air gap. Each membrane layer is made from a commercially available flexible circuit material that, as supplied, comprises a 127-micron-thick polyimide dielectric layer clad on both sides with 17.5-micron-thick copper layers. The copper layers are patterned into RF, bias, and control conductors. The T/R module is located on the back side of the ground plane and is RF-coupled to the patch element via a slot. The T/R module is a hybrid multilayer module assembled and packaged independently and attached to the membrane array. At the time of reporting the information for this article, an 8 16 passive array (not including T/R modules) and a 2 4 active array (including T/R modules) had been demonstrated, and it was planned to fabricate and test larger arrays

Detection of Structural Breaks in Copula Models

The paper presents the research results on detection of structural breaks in copula models of multivariate time-series. A nonparametric method of structural break identification and estimation is used and its asymptotic characteristics (probabilities of the I and II-type errors, probability of estimation error) are analyzed. Simulation test results applied to Clayton and Gumbel copulas are presented and discussedCopula; structural break; Kolmogorov-Smirnov statistics; interest rates; MosPrime; LIBOR; EURIBOR

Un Centre en périphérie : le Centre méditerranéen de création cinématographique (CMCC)

Le retour à Marseille de René Allio se dessine en 1974 et se précise dès 1975 par un rapport qu’il écrit au sujet d’un Centre de création cinématographique régional qu’il souhaite fonder dans sa ville natale. S’il revient dans la cité phocéenne à partir de 1977, c’est d’abord pour y préparer Retour à Marseille, son septième long métrage qu’il tourne en 1979. En même temps, il jette les bases de ce qui devient finalement le Centre méditer..

El empoderamiento de la población afrocolombiana a través de la etnoeducación en televisión

113 páginas.Trabajo de Máster Oficial Interuniversitario en Comunicación y Educación Audiovisual. Director/Tutor: Dr. Octavio Vázquez Aguado. Esta investigación se basó en la necesidad de comprender la forma de hacer incidencia desde la televisión como medio de comunicación masivo en la etnoeducación afrocolombiana donde las instituciones educativas, profesores, alumnos, productores, realizadores e investigadores entre otros quienes ayudaran a la visibilización de la cultura afrocolombiana sea conocida por la otredad,y se permita el respeto por la diferencia. El empezar a trabajar esto en los medios masivos además de la televisión va ser posible la interculturalidad entre las diferentes etnias y se va a ver reflejado en el comportamiento entre si. Este investigación abre la posibilidad a que los medios de comunicación puedan contar esas historias no contadas y de esa manera, conocer el comportamiento de los demás

Torocyte Membrane Endovesicles Induced by Octaethyleneglycol Dodecylether in Human Erythrocytes

AbstractEndovesicles induced in human erythrocytes by octaethyleneglycol dodecylether (C12E8) were studied by confocal laser scanning microscopy, using fluorescein isothiocyanate dextran as a nonspecific fluid marker. The endovesicles appeared to consist mainly of a ring-formed toroidal part joined with a central flat membrane segment. The torocyte contour length was several μm. There was usually one torocyte endovesicle per cell. The endovesicles seemed to be located near the cell surface. In sections of C12E8-treated erythrocytes transmission electron microscopy revealed the frequent occurrence of flat membrane structures with a bulby periphery, which apparently are cross sections of torocyte endovesicles. The possible physical mechanisms leading to the observed torocyte endovesicle shape are discussed. The torocyte endovesicles seem to be formed in a process in which an initially stomatocytic invagination loses volume while maintaining a large surface area. Because intercalation of C12E8 in the erythrocyte membrane induces inward membrane bending (stomatocytosis) we assume that C12E8 is preferentially located in the inner lipid layer of the erythrocyte membrane, i.e., in the outer lipid layer of the endovesicle membrane. It is suggested that local disturbances of the lipid molecules in the vicinity of the C12E8 molecules in the outer lipid layer of the endovesicle membrane form membrane inclusions with the effective shape of an inverted truncated cone. If the interaction between the inclusion and the membrane is weak, the membrane of such an endovesicle can be characterized by its negative spontaneous curvature, which may lead to a torocyte endovesicle shape with a small relative volume. Effects of a possible strong interaction between the C12E8-induced membrane inclusions and the membrane on the stability of the torocyte endovesicles are also indicated