A neuro-inspired system for online learning and recognition of parallel spike trains, based on spike latency and heterosynaptic STDP

Humans perform remarkably well in many cognitive tasks including pattern recognition. However, the neuronal mechanisms underlying this process are not well understood. Nevertheless, artificial neural networks, inspired in brain circuits, have been designed and used to tackle spatio-temporal pattern recognition tasks. In this paper we present a multineuronal spike pattern detection structure able to autonomously implement online learning and recognition of parallel spike sequences (i.e., sequences of pulses belonging to different neurons/neural ensembles). The operating principle of this structure is based on two spiking/synaptic neurocomputational characteristics: spike latency, that enables neurons to fire spikes with a certain delay and heterosynaptic plasticity, that allows the own regulation of synaptic weights. From the perspective of the information representation, the structure allows mapping a spatio-temporal stimulus into a multidimensional, temporal, feature space. In this space, the parameter coordinate and the time at which a neuron fires represent one specific feature. In this sense, each feature can be considered to span a single temporal axis. We applied our proposed scheme to experimental data obtained from a motor inhibitory cognitive task. The test exhibits good classification performance, indicating the adequateness of our approach. In addition to its effectiveness, its simplicity and low computational cost suggest a large scale implementation for real time recognition applications in several areas, such as brain computer interface, personal biometrics authentication or early detection of diseases.Comment: Submitted to Frontiers in Neuroscienc

Optically Induced Reorientation in Nematic Cylindrical Structures

Cyclindrical structures of nematics give rise to several opto-optical effects related to molecular reorientation. One of these effects is the formation of diffraction ring patterns similar to the ones observed in planar cells, but differing in shape. Another effect has been observed, namely a quasi-chaotic motion of rings with a very large angular spread; this motion can be obtained using a cw laser and high power densities. The phenomenon could be attributed to thermal motion, however, there are some features that cannot be explained by a purely thermal effect, e.g., a wavelength dependence of the threshold and the frequencies of the ring motion

Densities and phase equilibria of hydrogen, propane and vegetable oil mixtures. Experimental data and thermodynamic modeling

Heterogeneous catalytic gas-liquid reactions are intensified when carried out in the homogenous fluid phase by means of a supercritical co-solvent. For instance, supercritical propane is used to enhance yield in the hydrogenation of vegetable oils. Besides phase equilibrium knowledge, volumetric information is also needed to elucidate kinetic mechanisms and design continuous supercritical reactors. In this work, we report new experimental PvT data of the reactive mixture H2+sunflower oil+propane using the isochoric method. In addition, the phase equilibria and PvT data are modeled with the GCA and RK-PR equations of state, respectively. The isochoric method not only provides PvT information under the reaction conditions, but also the reactive system compressibility, key variable to attain enhanced transport properties in the supercritical reactors.Fil: Hegel, Pablo Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Cotabarren, Natalia Soledad. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Brignole, Esteban Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; ArgentinaFil: Pereda, Selva. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Bahía Blanca. Planta Piloto de Ingeniería Química. Universidad Nacional del Sur. Planta Piloto de Ingeniería Química; Argentina. University of KwaZulu-Natal; Sudáfric

Multiple primary and secondary sources for chemically similar obsidians from the area of portada covunco, west-central Neuquén, Argentina

In west-central Neuquén Province, Argentina, in the area around Estancia Llamuco, west of Zapala, south of Las Lajas and north-east of Lago Aluminé, there are multiple primary and secondary sources of obsidian. Primary sources occur within the south-east extension of the Plio-Quaternary volcanic chain that runs from Copahue volcano through Pino Hachado. Secondary sources include river-bed gravels within the valleys of Arroyo Cochicó Grande and Río Kilca as far south as where this river joins with Río Aluminé, and the Quaternary fluvial-glacial sediments cut by the valley of Río Covunco as far east as Portada Covunco. Visually variable obsidians from these two secondary sources include homogeneous black and grey-translucent types, porphyritic and banded types, and an abundant quantity of oxidized red and black obsidian. However, all these visually distinct obsidians have similar and unique chemistry, with Ba between 220 and 340ppm, different from any other obsidians previously reported from Neuquén, which all have Ba>500ppm, as do obsidians from sources to the north in Mendoza and to the west in Chile. This chemical distinctive obsidian has been exploited and transported over a wide area, beginning prior to 4000 bp, and occurs in local archaeological sites, as well as sites ≥ 300km to the north-east in La Pampa Province, ~430km to the south in Chubut Province, and >75km to the west across the Andean drainage divide in Chile.Fil: Stern, C. R.. State University of Colorado at Boulder; Estados UnidosFil: Pereda, I.. No especifíca;Fil: Aguerre, Ana Margarita. Universidad de Buenos Aires. Facultad de Filosofía y Letras. Instituto de Arqueología; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

El principio de razón suficiente

Según Alexander R. Pruss el principio de razón suficiente (PRS) es imprescindible para resolver dos problemas clásicos de la filosofía: 1) el problema de la regresión al infinito y 2) la no-emergencia de realidades ex nihilo. Además, el uso del PRS se correspondería con una explicación aristotélico-tomista de la estructura metafísica de los individuos. Sin embargo, la argumentación que desarrolla Pruss presenta algunos defectos que, en última instancia, llevan a concluir que el PRS es superfluo.According to Alexander R. Pruss the Principle of Sufficient Reason (PSR) is essential to solve two classical problems of philosophy: 1) the problem of infinite regress and 2) the non-emergence of entities ex nihilo. Furthermore, the use of the PSR would correspond to an Aristotelian-Thomistic explanation of the metaphysical structure of individuals. However, the argument developed by Pruss has some defects that ultimately lead to the conclusion that the PSR is superfluous

La mente del universo y la causalidad

En La mente del universo Mariano Artigas presenta un puente para conectar la ciencia y la teología. Una de las conexiones que se establecen entre ambas áreas del conocimiento pasa por la filosofía de la naturaleza, en concreto por el estudio de la causalidad; de hecho, en La mente del universo pueden encontrarse modos de entender y exponer la doctrina aristotélico-tomista de la causalidad que permiten, por un lado, la conexión entre ciencia y teología y, por otro, una mayor profundización en la comprensión filosófica del mundo natural.In The Mind of the Universe Mariano Artigas builds a bridge connecting science and theology. One of the connections he establishes between the two areas of knowledge goes through the philosophy of nature, specifically through the study of causality; in fact, in The Mind of the Universe can be found ways to understand and to expose the Aristotelian-Thomistic doctrine of causality that allow, on the one hand, the connection between science and theology and, on the other hand, going deeper into the philosophical understanding of the natural world

Principios metafísicos de las dinámicas naturales

Peter van Inwagen entiende la metafísica como el intento de acceder a la verdad última sobre el Mundo mediante la respuesta a preguntas fundamentales. En este planteamiento, la tarea del filósofo es elegir entre respuestas alternativas. Esta visión no coincide con la que tiene la tradición aristotélico-tomista: para ésta, la metafísica es la ciencia que estudia los principios de la realidad. Se estudia aquí qué quiere decir esta expresión y cómo se puede relacionar con el conocimiento científico de la naturaleza