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Search Results: 1 - 10 of 1554 matches for " Ramon Reig "
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Synaptic Transmission and Plasticity in an Active Cortical Network
Ramon Reig, Maria V. Sanchez-Vives
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000670
Abstract: Background The cerebral cortex is permanently active during both awake and sleep states. This ongoing cortical activity has an impact on synaptic transmission and short-term plasticity. An activity pattern generated by the cortical network is a slow rhythmic activity that alternates up (active) and down (silent) states, a pattern occurring during slow wave sleep, anesthesia and even in vitro. Here we have studied 1) how network activity affects short term synaptic plasticity and, 2) how synaptic transmission varies in up versus down states. Methodology/Principal Findings Intracellular recordings obtained from cortex in vitro and in vivo were used to record synaptic potentials, while presynaptic activation was achieved either with electrical or natural stimulation. Repetitive activation of layer 4 to layer 2/3 synaptic connections from ferret visual cortex slices displayed synaptic augmentation that was larger and longer lasting in active than in silent slices. Paired-pulse facilitation was also significantly larger in an active network and it persisted for longer intervals (up to 200 ms) than in silent slices. Intracortical synaptic potentials occurring during up states in vitro increased their amplitude while paired-pulse facilitation disappeared. Both intracortical and thalamocortical synaptic potentials were also significantly larger in up than in down states in the cat visual cortex in vivo. These enhanced synaptic potentials did not further facilitate when pairs of stimuli were given, thus paired-pulse facilitation during up states in vivo was virtually absent. Visually induced synaptic responses displayed larger amplitudes when occurring during up versus down states. This was further tested in rat barrel cortex, where a sensory activated synaptic potential was also larger in up states. Conclusions/Significance These results imply that synaptic transmission in an active cortical network is more secure and efficient due to larger amplitude of synaptic potentials and lesser short term plasticity.
Effective Reduced Diffusion-Models: A Data Driven Approach to the Analysis of Neuronal Dynamics
Gustavo Deco ,Daniel Martí,Anders Ledberg,Ramon Reig,Maria V. Sanchez Vives
PLOS Computational Biology , 2009, DOI: 10.1371/journal.pcbi.1000587
Abstract: We introduce in this paper a new method for reducing neurodynamical data to an effective diffusion equation, either experimentally or using simulations of biophysically detailed models. The dimensionality of the data is first reduced to the first principal component, and then fitted by the stationary solution of a mean-field-like one-dimensional Langevin equation, which describes the motion of a Brownian particle in a potential. The advantage of such description is that the stationary probability density of the dynamical variable can be easily derived. We applied this method to the analysis of cortical network dynamics during up and down states in an anesthetized animal. During deep anesthesia, intracellularly recorded up and down states transitions occurred with high regularity and could not be adequately described by a one-dimensional diffusion equation. Under lighter anesthesia, however, the distributions of the times spent in the up and down states were better fitted by such a model, suggesting a role for noise in determining the time spent in a particular state.
Editorial Article for Open Journal of Antennas and Propagation  [PDF]
Càndid Reig
Open Journal of Antennas and Propagation (OJAPr) , 2013, DOI: 10.4236/ojapr.2013.11002
Abstract: Editorial Article for Open Journal of Antennas and Propagation
Por qué un coro en el instituto?
Reig, David
Revista de la Lista Electrónica Europea de Música en la Educación , 2001,
Abstract:
Jacques Roubaud, piéton de Paris - échantillons de mémoire urbaine
Christophe Reig
Revue Electronique de Litterature Francaise : RELIEF , 2008,
Abstract: Jacques Roubaud sillonne depuis plus de cinquante ans le labyrinthe parisien en forme d’escargot. La prose de mémoire du Grand Incendie de Londres, les poèmes de La Forme d’une ville change plus vite, hélas, que le c ur des humains… chantent une capitale tour à tour honnie et acclimatée, un Paris pluriel qui suscite le pari d’un art poétique prouvant le mouvement en marchant, sans faire l’économie du rythme. Après Baudelaire, Apollinaire, Queneau et bien d’autres encore, Roubaud court et recourt les rues de Paris, en quête de lui-même, planifiant dans la Capitale autant de parcours de mémoire que de trajets poétiques.
On the nature of the X-ray source 1E 1024.0--5732/Wack 2134
Pablo Reig
Physics , 1999,
Abstract: Two different models have been put forward to explain the origin of the X-ray emission of the unusual X-ray source 1E 1024.0-5732/Wack 2134: a high-mass X-ray binary system (HMXB) and a colliding wind binary (CWB). We present new optical and X-ray data in an attempt to clarify the nature of this system. The data seem to favour the colliding wind model since the optical spectra show characteristics of both, a Wolf-Rayet and an O-type star, implying that these two type of stars may be present in the system. The lack of coherent modulation (pulsations) and the relatively soft and low luminosity X-ray emission seems to exclude the presence of a neutron star as the body generating the X-ray emission. We present the first X-ray energy spectrum of this source at energies above 3 keV and discuss the implications of the spectral parameters obtained from the model fitting. We comment on the fact that the iron lines in CWB are centred at higher energies, ~ 6.6 keV, than those detected in supergiant HMXB, where a value of 6.4 keV is found, implying that the degree of ionisation of iron is higher in CWB.
Be/X-ray binaries
Pablo Reig
Physics , 2011, DOI: 10.1007/s10509-010-0575-8
Abstract: The purpose of this work is to review the observational properties of Be/X-ray binaries. The open questions in Be/X-ray binaries include those related to the Be star companion, that is, the so-called "Be phenomenon", such as, timescales associated to the formation and dissipation of the equatorial disc, mass-ejection mechanisms, V/R variability, and rotation rates; those related to the neutron star, such as, mass determination, accretion physics, and spin period evolution; but also, those that result from the interaction of the two constituents, such as, disc truncation and mass transfer. Until recently, it was thought that the Be stars' disc was not significantly affected by the neutron star. In this review, I present the observational evidence accumulated in recent years on the interaction between the circumstellar disc and the compact companion. The most obvious effect is the tidal truncation of the disc. As a result, the equatorial discs in Be/X-ray binaries are smaller and denser than those around isolated Be stars.
Waning Sovereignty? The Kindred Myths of “Origins” and “Vanishing” of the State  [PDF]
Ramon Maiz
Open Journal of Political Science (OJPS) , 2017, DOI: 10.4236/ojps.2017.73032
Abstract: This article discusses, from an historical-neo-institutionalist and relational-strate- gic perspective, the postmodern thesis of the end of the state due to the increasing processes of world globalization. The main hypothesis is that the arguments which predict the structural crisis or the disappearance of the State in the age of neo-liberal globalization have their roots in a theoretically and historically implausible concept of sovereignty that ignores and distorts central aspects of statehood and state-building in terms of both institutional structure and political action. The myth of the “origins” of the State in Medieval or Renaissance times shares with the postmodern vision of the “vanishing” of the state, the same underlying misconception of the scope and limits of the state power. Sovereignty (the monopolization of political power) was always a claim, a desiderata, a contested andunfinished political project not an accomplished empirical fact.
PARA UNA TEORíA INFORMATIVA DEL DOCUMENTO: EXTENSIóN Y APLICABILIDAD DEL CONCEPTO
Reig Crua?es,José;
Revista Interamericana de Bibliotecología , 2005,
Abstract: this article provides an exhaustive review of the concept of the document. beginning with an informative perspective, which understands the document as a manifestation of an act of communication, it establishes the axes that identify the basic functions of fixation and the transmission of messages. the proliferation of a new generation of types of documents makes it necessary to revise the components of the basic axes in order to verify and expand the field of validity and application of the concept, confirming its sufficiency and its current theoretical consistency.
La creación del espacio trágico en la obra de Gabriel García Márquez: Una lectura sofoclea
Montserrat Reig Calpe
Synthesis (La Plata) , 2012,
Abstract: La influencia de Sófocles y, concretamente, de las tragedias tebanas en la obra de García Márquez se manifiesta a niveles diversos: en la construcción de la trama, en la elaboración del personaje tiránico, en los temas de la violencia y el destino y, por supuesto, en el tratamiento del tiempo y del espacio. En este artículo se analiza la creación del espacio en García Márquez a través de dos elementos contrapuestos que provienen de su lectura de la tragedia sofoclea: el genos, símbolo de un espacio cerrado y ligado a un tiempo "redondo", el espacio del relato, y la polis, un lugar abierto y lejano, donde se produce la Historia con mayúsculas. Esta dicotomía será observada en distintas obras de García Márquez, pero especialmente en Edipo Alcalde. El conflicto trágico de la discordia civil se refleja, así pues, en la construcción de un espacio único, claustrofóbico y corrompido The influence of Sophocles, particularly of his Theban tragedies, on García Márquez's work can be perceived at several different levels: in the construction of the plot, in the conception of the Tyrant character, in the violence and fate themes, and of course in the treatment of time and space. The focus of this paper lies on the construction of space in García Márquez's work through two opposed elements originating in his reading of Sophoclean tragedy: the genos, symbolic of a closed space, linked to a "round" time, which is the space of the narration; and the polis, an open, remote space, in which the time of History unfolds. This dichotomy is analyzed in several works by García Márquez, with special attention paid to Edipo alcalde. Thus, the tragic conflict of civil discord finds its reflection in a single, claustrophobic, and corrupted space
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