69,901 research outputs found

    On problems in the calculus of variations in increasingly elongated domains

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    We consider minimization problems in the calculus of variations set in a sequence of domains the size of which tends to infinity in certain directions and such that the data only depend on the coordinates in the directions that remain constant. We study the asymptotic behavior of minimizers in various situations and show that they converge in an appropriate sense toward minimizers of a related energy functional in the constant directions

    Learning Temporal Contexts and Priming-Preparation Modes for Pattern Recognition

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    The system presented here is based on neurophysiological and electrophysiological data. It computes three types of increasingly integrated temporal and probability contexts, in a bottom-up mode. To each of these contexts corresponds an increasingly specific top-down priming effect on lower processing stages, mostly pattern recognition and discrimination. Contextual learning of time intervals, events' temporal order or sequential dependencies and events' prior probability results from the delivery of large stimuli sequences. This learning gives rise to emergent properties which closely match the experimental data.Institut national de la santé et de la recherche médicale; Ministère de la Défense Nationale (DGA/DRET 911470/AOOO/DRET/DS/DR); Consejo Nacional de Ciencia y Tecnología (63462

    An Integrated Neural Network-Event-Related Potentials Model of Temporal and Probability Context Effects on Event Categorization

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    We present a neural network that adapts and integrates several preexisting or new modules to categorize events in short term memory (STM), encode temporal order in working memory, evaluate timing and probability context in medium and long term memory. The model shows how processed contextual information modulates event recognition and categorization, focal attention and incentive motivation. The model is based on a compendium of Event Related Potentials (ERPs) and behavioral results either collected by the authors or compiled from the classical ERP literature. Its hallmark is, at the functional level, the interplay of memory registers endowed with widely different dynamical ranges, and at the structural level, the attempt to relate the different modules to known anatomical structures.INSERM; NATO; DGA/DRET (911470/A000/DRET/DS/DR

    El dret civil des de la successió per causa de mort

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    Treballs Finals de Grau de Dret. Universitat de Barcelona. Curs: 2014-2015. Tutora: Lidia Arnau ReventósAquest dictamen ha estat elaborat com a Treball Final del Grau de Dret, Grau que he cursat a la Facultat de Dret de la Universitat de Barcelona, i el qual versa sobre diverses qüestions de Dret Civil

    Introducción a la fiscalidad empresarial

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    Departament de Dret Públic. C05: Dret Empresarial I

    Drosophila RET contains an active tyrosine kinase and elicits neurotrophic activities in mammalian cells

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    AbstractThe RET receptor tyrosine kinase controls kidney organogenesis and development of subpopulations of enteric and sensory neurons in different vertebrate species, including humans, rodents, chicken and zebrafish. RET is activated by binding to a ligand complex formed by a member of the glial cell line-derived neurotrophic factor (GDNF) family of neurotrophic factors bound to its cognate GFRα GPI-linked co-receptor. Despite the absence of GDNF or GFRα molecules in the Drosophila genome, a RET orthologue (dRET) has recently been described in this organism and shown to be expressed in subpopulations of cells of the excretory, digestive and nervous systems, thus resembling the expression pattern of RET in vertebrates. In this study, we report on the initial biochemical and functional characterization of the dRET protein in cell culture systems. Full-length dRET could be produced in mammalian and insect cells. Similar to its human counterpart (hRET), overexpression of dRET resulted in its ligand-independent tyrosine phosphorylation, indicating that it bears an active tyrosine kinase. Unlike hRET, however, the extracellular domain of dRET was unable to interact with mammalian GDNF and GFRα1. Self association between dRET molecules could neither be detected, indicating that dRET is incapable of mediating cell adhesion by homophilic interactions. A chimeric molecule comprising the extracellular domain of hRET and the kinase domain of dRET was constructed and used to probe ligand-mediated downstream activities of the dRET kinase in PC12 cells. GDNF stimulation of cells transfected with the hRET/dRET chimera resulted in neurite outgrowth comparable to that obtained after transfection of wild-type hRET. These results indicate significant conservation between the biological effects elicited by the human and Drosophila RET kinases, and suggest functions for dRET in neuronal differentiation in the fly

    La garantia jurídica de la democràcia com a dret fonamental. Una anàlisi de la jurisprudència del Tribunal Constitucional sobre la participació política

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    L'art. 23 de la CE consagra el dret fonamental dels ciutadans a participar en els assumptes públics, preveient-ne dues grans modalitats, la participació directa i la representativa. La doctrina jurisprudencial elaborada pel Tribunal Constitucional durant quasi trenta anys ha atorgat a aquest dret una configuració especial: el seu abast es veu reduït a l'estricta participació política (aspecte que tindrà conseqüències en el vessant de la participació directa reduïda a la iniciativa legislativa popular i el referèndum, deixant fora del seu abast altres possibles institucions participatives); però, per altra banda, amplia el nucli de protecció del dret, garantint no només l'accés dels ciutadans als càrrecs públics (un ius ad officium) en condicions d'igualtat; sinó també el dret dels representants a romandre en el seu càrrec lliures de qualsevol pertorbació i el tercer contingut, el dret dels representants a exercir les facultats inherents a la funció que desenvolupen tot atorgant-los un status constitucionalment garantit. Aquesta construcció jurisprudencial del dret esdevé així la garantia jurídica de la democràcia. Certament, aquest enteniment del dret fonamental de participació té conseqüències prou rellevants en l'àmbit dels partits polítics com a instruments fonamentals per a la participació política. L'abundància de resolucions per part del Tribunal Constitucional, majoritàriament a través de recursos d'empara, ha fet possible l'entrada del dret de participació en dos àmbits singularment rellevants del procés polític, com són el sistema electoral i el dret parlamentari, i ha permès al Tribunal construir tota una teoria de la representació política en seu de drets fonamentals
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