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Search Results: 1 - 10 of 79226 matches for " David González-Forero? "
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The A-Current Modulates Learning via NMDA Receptors Containing the NR2B Subunit
ángela Fontán-Lozano, Irene Suárez-Pereira, David González-Forero, ángel Manuel Carrión
PLOS ONE , 2011, DOI: 10.1371/journal.pone.0024915
Abstract: Synaptic plasticity involves short- and long-term events, although the molecular mechanisms that underlie these processes are not fully understood. The transient A-type K+ current (IA) controls the excitability of the dendrites from CA1 pyramidal neurons by regulating the back-propagation of action potentials and shaping synaptic input. Here, we have studied how decreases in IA affect cognitive processes and synaptic plasticity. Using wild-type mice treated with 4-AP, an IA inhibitor, and mice lacking the DREAM protein, a transcriptional repressor and modulator of the IA, we demonstrate that impairment of IA decreases the stimulation threshold for learning and the induction of early-LTP. Hippocampal electrical recordings in both models revealed alterations in basal electrical oscillatory properties toward low-theta frequencies. In addition, we demonstrated that the facilitated learning induced by decreased IA requires the activation of NMDA receptors containing the NR2B subunit. Together, these findings point to a balance between the IA and the activity of NR2B-containing NMDA receptors in the regulation of learning.
Membrane-Derived Phospholipids Control Synaptic Neurotransmission and Plasticity
Victoria García-Morales?,Fernando Montero?,David González-Forero,Guillermo Rodríguez-Bey?,Laura Gómez-Pérez?,María Jesús Medialdea-Wandossell?,Germán Domínguez-Vías?,José Manuel García-Verdugo?,Bernardo Moreno-López
PLOS Biology , 2015, DOI: 10.1371/journal.pbio.1002153
Abstract: Synaptic communication is a dynamic process that is key to the regulation of neuronal excitability and information processing in the brain. To date, however, the molecular signals controlling synaptic dynamics have been poorly understood. Membrane-derived bioactive phospholipids are potential candidates to control short-term tuning of synaptic signaling, a plastic event essential for information processing at both the cellular and neuronal network levels in the brain. Here, we showed that phospholipids affect excitatory and inhibitory neurotransmission by different degrees, loci, and mechanisms of action. Signaling triggered by lysophosphatidic acid (LPA) evoked rapid and reversible depression of excitatory and inhibitory postsynaptic currents. At excitatory synapses, LPA-induced depression depended on LPA1/Gαi/o-protein/phospholipase C/myosin light chain kinase cascade at the presynaptic site. LPA increased myosin light chain phosphorylation, which is known to trigger actomyosin contraction, and reduced the number of synaptic vesicles docked to active zones in excitatory boutons. At inhibitory synapses, postsynaptic LPA signaling led to dephosphorylation, and internalization of the GABAAγ2 subunit through the LPA1/Gα12/13-protein/RhoA/Rho kinase/calcineurin pathway. However, LPA-induced depression of GABAergic transmission was correlated with an endocytosis-independent reduction of GABAA receptors, possibly by GABAAγ2 dephosphorylation and subsequent increased lateral diffusion. Furthermore, endogenous LPA signaling, mainly via LPA1, mediated activity-dependent inhibitory depression in a model of experimental synaptic plasticity. Finally, LPA signaling, most likely restraining the excitatory drive incoming to motoneurons, regulated performance of motor output commands, a basic brain processing task. We propose that lysophospholipids serve as potential local messengers that tune synaptic strength to precedent activity of the neuron.
Capturas ícticas incidentales de la pesca ornamental en el período de aguas bajas en el área de influencia de Puerto Carre?o, Orinoquia colombiana
Prada-Pedreros,Saúl; González-Forero,Jhon; Mondragón-Estupi?an,Juan;
Universitas Scientiarum , 2009,
Abstract: objective. the present study assesses the incidental fish catches in the fishing of ornamental species in terms of richness and abundance within the influence zone of puerto carre?o, vichada, colombia. materials and methods. samplings were carried out in the orinoco river and bita river and ca?o negro stream during the low-water season, in march and april of 2007. target and incidental species collected during the ornamental fishing totalized 152. catches per unit of effort (cpue) as well as the percentage composition of fish catches of target vs. incidental species were estimated. results. the highest values of cpue of fishes with ornamental value correspond to: dicrossus maculatus, hemigrammus rodhostomus, corydoras cf. melanistius, peckoltia sp. 2 and hemiancistrus sp., and the highest values of incidental species were for: hemigrammus sp., moenkhausia sp., hemigrammus levis, aphanothorulus cf. ammophilus, triportheus sp. y moenkhausia lepidura. the richness percentage of incidental species varied between 92% and 98%. however the abundance percentage of target species was always higher than the percentage of incidental catches varying between 73% and 83% with the exception of that obtained in the fisheries of the orinoco river outcrops that was 17%. conclusions. the impact of the fishing ornamental fish on species taught incidentally is seen mainly at the level of richness, but not at the level of abundance.
Capturas ícticas incidentales de la pesca ornamental en el período de aguas bajas en el área de influencia de Puerto Carre o, Orinoquia colombiana
Saúl Prada-Pedreros,Jhon González-Forero,Juan Mondragón-Estupi?an
Universitas Scientiarum , 2009,
Abstract: Incidental bycatch by ornamental fishing during the low-water season in the influence zone of Puerto Carre o, ColombianOrinoco Basin. Objective. The present study assesses the incidental fish catches in the fishing of ornamental species in terms ofrichness and abundance within the influence zone of Puerto Carre o, Vichada, Colombia. Materials and methods. Samplings werecarried out in the Orinoco River and Bita River and Ca o Negro stream during the low-water season, in March and April of 2007. Targetand incidental species collected during the ornamental fishing totalized 152. Catches per unit of effort (CPUE) as well as the percentagecomposition of fish catches of target vs. incidental species were estimated. Results. The highest values of CPUE of fishes with ornamentalvalue correspond to: Dicrossus maculatus, Hemigrammus rodhostomus, Corydoras cf. melanistius, Peckoltia sp. 2 and Hemiancistrussp., and the highest values of incidental species were for: Hemigrammus sp., Moenkhausia sp., Hemigrammus levis, Aphanothorulus cf.ammophilus, Triportheus sp. y Moenkhausia lepidura. The richness percentage of incidental species varied between 92% and 98%.However the abundance percentage of target species was always higher than the percentage of incidental catches varying between 73%and 83% with the exception of that obtained in the fisheries of the Orinoco River outcrops that was 17%. Conclusions. The impact of thefishing ornamental fish on species taught incidentally is seen mainly at the level of richness, but not at the level of abundance.
Fusión automática de imágenes a través de la obtención de sinogramas
Forero Manuel Guillermo,González Marcela
Ingeniería e Investigación , 1998,
Abstract: El desarrollo de técnicas de fusión tiene un alto costo computacional y demandan, por el uso que de ellas se da, excelentes resultados. Este trabajo compara la aplicación de dos técnicas de retroproyección (proyección de máxima intensidad y promedio) para la obtención de sinogramas, los cuales serán utilizados como herramienta analítica dentro del procedimiento, junto con un par de métodos de correlación que permiten fusionar dos imágenes del mismo tipo; estos resultados constituyen el material principal de la fusión automática de imágenes propuesta. Este procedimiento no requiere el uso de marcadores externos, ni de marcadores corporales. Los principios esenciales aplicados en este artículo han sido previamente utilizados en la fusión de imágenes.
ESTUDIO TEóRICO DEL EFECTO ISOTóPICO DE HIDRóGENO EN EL ADUCTO BORANO-CARBONILO
Forero,Neftalí; González,Sergio A; Reyes,Andrés;
Revista Colombiana de Química , 2009,
Abstract: we have investigated the hydrogen isotope effect on the geometry, the electronic structure and the stability of the borane-carbonile adduct, by using the nuclear-electronic molecular orbital method (nemo) which has been implemented in the apmo software. we have found that an increase of the mass of the hydrogen isotope reduces the boron-hydrogen and carbon-oxygen bond lengths while increasing the boron-carbon distance. in this study, the stability of the adduct has been analyzed in terms of formation energies and b-c bond distances. we have found that the increase of the isotope mass weakens the b-c bond. we tried to give an explaination to this phenomenon based on lewis acidity concept but it predicted the wrong results. a reactivity model based on the energy differences of borane lumo orbitais offered a correct explaination to this effect.
LA ACCIóN PúBLICA DE INCONSTITUCIONALIDAD: A PROPóSITO DE LOS 100 A?OS DE SU VIGENCIA EN COLOMBIA
Mendieta González,David;
Vniversitas , 2010,
Abstract: the citizen action of unconstitutionality in colombia is going to be one hundred years of uninterrupted validity. it means that in this country there were on abstracted control of constitutionality ten years before of the creation of the austrian constitutional court and nineteen years before kelsen created his theory of negative legislator. about the two latest, these have been a lot of discussions in the international field of laws but the colombian constitutionalism has not been recognized as a pioneer in this field. from the beginning of the colombian constitutionalism there have been mechanism of direct citizen participation towards acts emanated from the public powers which have been strengthened on weakened according to the historic time is going on. a different case has occurred in europe where historically the politic control is not done by the citizens but their representants. the orthodoxy of the european continent does not accept the public action of unconstitutionality as a mechanism valid to avoid the abuse of power argued the constitutional court's collapse. on the other hand in america, this figure raises as institution to protect the individual and minorities rights against the power presidents and parlaments.
La sublimación artística y su objeto // Artistic sublimation and its object
David González
Affectio Societatis , 2012,
Abstract: El presente artículo versa sobre la conceptualización de la sublimación artística en la obra freudiana y la ense anza lacaniana, para dilucidar semejanzas y diferencias, re-actualizando el concepto en el plano de la discusión teórica. De esta manera se realiza un recorrido exploratorio del concepto en ambos autores. Desde una perspectiva psicoanalítica se redefinen los conceptos de objeto y la Cosa contenidos en la definición lacaniana de la sublimación. // This article deals with the conceptualization of artistic sublimation in Freud's work and Lacan's teaching in order to elucidate similarities and differences, and so it updates the concept in terms of the theoretical discussion. In that way, an exploratory route of the concept is carried out in both authors. From a psychoanalytic perspective, the concepts of object and Thing -contained in the Lacanian definition of sublimation- are redefined
LA ACCIóN PúBLICA DE INCONSTITUCIONALIDAD: A PROPóSITO DE LOS 100 A OS DE SU VIGENCIA EN COLOMBIA CONSTITUTIONAL ACTION: ON ITS 100TH ANNIVERSARY OF VALIDITY IN COLOMBIA
David Mendieta González
Vniversitas , 2010,
Abstract: La acción pública de inconstitucionalidad está próxima a cumplir cien a os de existencia ininterrumpida en Colombia, lo que significa que en nuestro país estábamos haciendo control de constitucionalidad abstracto diez a os antes de que se creara el Tribunal Constitucional austríaco y diecinueve antes de que KELSEN propusiera su teoría del legislador negativo. De estos dos últimos hechos mucho se ha dicho a nivel internacional, pero no se ha reconocido al derecho constitucional colombiano como pionero de este tipo de control. Desde los inicios de nuestro constitucionalismo han existido mecanismos de participación directa de los ciudadanos frente a actos emanados de los poderes públicos, mecanismos que se han fortalecido o debilitado según el momento histórico por el que atravesemos. Algo diferente ocurrió en Europa, donde históricamente el control político no es realizado por los ciudadanos sino por sus representantes. La ortodoxia del viejo continente no acepta la acción pública de inconstitucionalidad como un mecanismo válido para evitar el abuso del poder, con el argumento de que esto significaría una gran congestión del tribunal constitucional. Pero en América esta figura se alza como una herramienta de protección de las minorías e individuos frente a los poderes Ejecutivo y Legislativo. The citizen action of unconstitutionality in Colombia is going to be one hundred years of uninterrupted validity. It means that in this country there were on abstracted control of constitutionality ten years before of the creation of the Austrian Constitutional Court and nineteen years before Kelsen created his theory of negative legislator. About the two latest, these have been a lot of discussions in the international field of laws but the Colombian constitutionalism has not been recognized as a pioneer in this field. From the beginning of the Colombian constitutionalism there have been mechanism of direct citizen participation towards acts emanated from the public powers which have been strengthened on weakened according to the historic time is going on. A different case has occurred in Europe where historically the politic control is not done by the citizens but their representants. The orthodoxy of the European continent does not accept the public action of unconstitutionality as a mechanism valid to avoid the abuse of power argued the constitutional court's collapse. On the other hand in America, this figure raises as institution to protect the individual and minorities rights against the power presidents and parlaments.
Estudio sobre el dise o y construcción de mezclas bituminosas en caliente con granos de caucho reciclado, empleando husos granulométricos espa oles
González Herrera, David
Informes de la Construccion , 1997,
Abstract:
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