2,371 research outputs found

    Connexin-dependent neuroglial networking as a new therapeutic target

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    Astrocytes and neurons dynamically interact during physiological processes, and it is now widely accepted that they are both organized in plastic and tightly regulated networks. Astrocytes are connected through connexin-based gap junction channels, with brain region specificities, and those networks modulate neuronal activities, such as those involved in sleep-wake cycle, cognitive, or sensory functions. Additionally, astrocyte domains have been involved in neurogenesis and neuronal differentiation during development; they participate in the "tripartite synapse" with both pre-synaptic and post-synaptic neurons by tuning down or up neuronal activities through the control of neuronal synaptic strength. Connexin-based hemichannels are also involved in those regulations of neuronal activities, however, this feature will not be considered in the present review. Furthermore, neuronal processes, transmitting electrical signals to chemical synapses, stringently control astroglial connexin expression, and channel functions. Long-range energy trafficking toward neurons through connexin-coupled astrocytes and plasticity of those networks are hence largely dependent on neuronal activity. Such reciprocal interactions between neurons and astrocyte networks involve neurotransmitters, cytokines, endogenous lipids, and peptides released by neurons but also other brain cell types, including microglial and endothelial cells. Over the past 10 years, knowledge about neuroglial interactions has widened and now includes effects of CNS-targeting drugs such as antidepressants, antipsychotics, psychostimulants, or sedatives drugs as potential modulators of connexin function and thus astrocyte networking activity. In physiological situations, neuroglial networking is consequently resulting from a two-way interaction between astrocyte gap junction-mediated networks and those made by neurons. As both cell types are modulated by CNS drugs we postulate that neuroglial networking may emerge as new therapeutic targets in neurological and psychiatric disorders

    Mean curvature flow without singularities

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    We study graphical mean curvature flow of complete solutions defined on subsets of Euclidean space. We obtain smooth long time existence. The projections of the evolving graphs also solve mean curvature flow. Hence this approach allows to smoothly flow through singularities by studying graphical mean curvature flow with one additional dimension.Comment: 19 pages, 4 figure

    Spherically Symmetric Solutions in M\o ller's Tetrad Theory of Gravitation

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    The general solution of M\o ller's field equations in case of spherical symmetry is derived. The previously obtained solutions are verified as special cases of the general solution.Comment: LaTeX2e with AMS-LaTeX 1.2, 8 page

    Entomological fauna associated with Aguaribay : Mendoza (Argentina)

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    En los relevamientos de especias dañinas y benéficas presentes en el aguaribay (Schinus molle L. var. Areira), para inventariar su entomofauna se efectuaron observaciones en distintas zonas de Mendoza (Argentina) en 1988/91 y 1994/96, confirmando y actualizando la bibliografía. Se recolectó material a campo para su identificación sistemática. Se evaluaron daños y se los documentó fotográficamente. En el laboratorio se conservaron muestras con parasitoides hasta la aparición de adultos para su clasificación, registrándose 8 especies de Homoptera, 7 de Hymenoptera, 7 de Coleoptera, 5 de Lepidoptera, 4 de Diptera, 4 de Thysanoptera, 2 de Hemiptera y 2 de Neuroptera. Las principales especies que afectan al Aguaribay son Calophya sp. (Homoptera - Psyllidae), Ceroplastes grandis (Homoptera - Coccidae) y Aphis schinifoliae (Homoptera - Aphididae). También cuenta con una importante fauna benéfica: coccinélidos, parasitoides, sírfidos y crisópidos.Pest and beneficial species present in Schinus molle L. var. Areira were monitoring in order to obtain an inventory of its entomological fauna. It was made observations in different zones of Mendoza from 1988 to 1991, and then, between 1994 and 1996, it was confirmed further observations and it was brought up to day bibliographical revisions. It was collected material in field in order to made its systematic identification. Damages were evaluated and documented photographically. Samples with parasitoids were stored in laboratory until the appearance of adults for their classification. It was registered: 8 species of Homoptera, 7 of Hymenoptera, 7 of Coleop-tera, 5 of Lepidoptera, 4 of Diptera, 4 of Thysanoptera, 2 of Hemiptera and 2 of Neuroptera. The main pest are: Calophya sp. (Homoptera - Psyllidae), Ceroplastes grandis (Homoptera - Coccidae) and Aphis schinifoliae (Homoptera - Aphididade). Also, there is an important beneficial fauna: Coccinellidae, parasitoids, Syrphidae and Chrysopidae.Fil: Sáez, César C.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: Mácola, Guido S.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: Holgado, Miriam G.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias BiológicasFil: García Sáez, José G.. Universidad Nacional de Cuyo. Facultad de Ciencias Agrarias. Departamento de Ciencias Biológica

    Vacuum type I spacetimes and aligned Papapetrou fields: symmetries

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    We analyze type I vacuum solutions admitting an isometry whose Killing 2--form is aligned with a principal bivector of the Weyl tensor, and we show that these solutions belong to a family of type I metrics which admit a group G3G_3 of isometries. We give a classification of this family and we study the Bianchi type for each class. The classes compatible with an aligned Killing 2--form are also determined. The Szekeres-Brans theorem is extended to non vacuum spacetimes with vanishing Cotton tensor.Comment: 19 pages; a reference adde

    Simulador de máquinas de Turing para fines didácticos

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    Se presenta un programa simulador escrito para ayudar a los estudiantes a comprender el concepto de máquina de Turing y a probar y corregir sus diseños de algoritmos con esta máquina. En una primera parte se describe el simulador desde el punto de vista de su uso, en el que cabe resaltar la representación del esquema funcional en la forma de quíntuplas, junto a una serie de opciones de explotación. La segunda y última parte se dedica a las características del programa, ocupación de memoria, representación y manejo de estados internos, simulación de la cinta y otras técnicas propias del programa o del miniordenador en el que aquel ha sido instrumentado

    ¿Un sistema educativo comprensivo?

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    Any good educational system tries to keep the maximum number of students in the educational system for as long as possible, where he or she will receive a quality education which will prepare him or her for higher education and the labour market. In other words, they fight for a comprehensive educational system. The LOMCE is going to achieve the complete opposite. We shall analyze this more deeply in the following paragraphs. Keywords: Vocational training, higher vocational training, educational method, scholar evaluation, exam, income test, scholar dropout, basic education, secondary education, postsecondary education, higher education, private school, public school.Ningún sistema educativo intenta mantener el máximo número de estudiantes en el sistema educativo durante el mayor tiempo posible, donde el o ella recibirá una educación de calidad la cual los preparará para la educación superior y el mercado laboral. En otras palabras, ellos luchan por un sistema educativo comprensivo. La LOMCE va a lograr todo lo contrario. Nosotros analizaremos esto más profundamente en los siguientes párrafos.ReiDoCrea. Departamento de Psicología Social. Universidad de Granada

    Beam deconvolution in noisy CMB maps

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    The subject of this paper is beam deconvolution in small angular scale CMB experiments. The beam effect is reversed using the Jacobi iterative method, which was designed to solved systems of algebraic linear equations. The beam is a non circular one which moves according to the observational strategy. A certain realistic level of Gaussian instrumental noise is assumed. The method applies to small scale CMB experiments in general (cases A and B), but we have put particular attention on Planck mission at 100 GHz (cases C and D). In cases B and D, where noise is present, deconvolution allows to correct the main beam distortion effect and recover the initial angular power spectrum up to the end of the fifth acoustic peak. An encouraging result whose importance is analyzed in detail. More work about deconvolution in the presence of other systematics is in progress. This paper is related to the Planck LFI activities.Comment: 24 pages, 9 figures. submitted to Astronomy and Astrophysic
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