A Heterosynaptic Spiking Neural System for the Development of Autonomous Agents

Artificial neural systems for computation were first proposed three quarters of a century ago and the concepts developed by the pioneers still shape the field today. The first generation of neural systems was developed in the nineteen forties in the context of analogue electronics and the theoretical research in logic and mathematics that led to the first digital computers in nineteen forties and fifties. The second generation of neural systems implemented on digital computers was born in the nineteen fifties and great progress was made in the subsequent half century with neural networks being applied to many problems in pattern recognition and machine learning. Through this history there has been an interplay between biologically inspired neural systems and their implementation by engineers on digital machines. This thesis concerns the third generation of neural networks, Spiking Neural Networks, which is making possible the creation of new kinds of brain inspired computing architectures that offer the potential to increase the level of realism and sophistication in terms of autonomous machine behaviour and cognitive computing. This thesis presents the development and demonstration of a new theoretical architecture for third generation neural systems, the Integrate-and-Fire based Spiking Neural Model with extended Neuro-modulated Spike Timing Dependent Plasticity capabilities. This proposed architecture overcomes the limitation of the homosynaptic architecture underlying existing implementations of spiking neural networks that it lacks a natural spike timing dependent plasticity regulation mechanism, and this results in ‘run away’ dynamics. To overcome this ad hoc procedures have been implemented to overcome the ‘run away’ dynamics that emerge from the use of spike timing dependent plasticity among other hebbian-based plasticity rules. The new heterosynaptic architecture presented, explicitly abstracts the modulation of complex biochemical mechanisms into a simplified mechanism that is suitable for the engineering of artificial systems with low computational complexity. Neurons work by receiving input signals from other neurons through synapses. The difference between homosynaptic and heterosynaptic plasticity is that, in the former the change in the properties of a synapse (e.g. synaptic efficacy) depends on the point to point activity in either of the sending and receiving neurons, in contrast for heterosynaptic plasticity the change in the properties of a synapse can be elicited by neurons that are not necessary presynaptic or postsynaptic to the synapse in question. The new architecture is tested by a number of implementations in simulated and real environments. This includes experiments with a simulation environment implemented in Netlogo, and an implementation using Lego Mindstorms as the physical robot platform. These experiments demonstrate the problems with the traditional Spike timing dependent plasticity homosynaptic architecture and how the new heterosynaptic approach can overcome them. It is concluded that the new theoretical architecture provides a natural, theoretically sound, and practical new direction for research into the role of modulatory neural systems applied to spiking neural networks

La extradición en el gobierno de la Prosperidad Democrática: caracterización y análisis de la extradición pasiva a Estados Unidos entre 2011 y 2014

21 p.La extradición, en su concepción clásica, es un instrumento de cooperación judicial internacional o de asistencia judicial entre Estados soberanos. Su carácter instrumental respecto del ejercicio del ius puniendi por los Estados se orienta a que las fronteras territoriales no constituyan un obstáculo absoluto a sus pretensiones punitivas. No obstante, también son múltiples los debates alrededor de la cesión de soberanía que implica este tipo de figuras, frente a los cuales se responde que la naturaleza de la fuente específica que las regula -los tratados- y el principio de reciprocidad -cuyo fundamento es el acuerdo interestatal y el reconocimiento de un igual estatus internacional de los Estados- resultan ser un reflejo de esta soberanía.El presente capítulo forma parte del proceso de investigación formativa adelantado en el marco del Observatorio de Cooperación Internacional y Administración de Justicia Penal de la Universidad Católica de Colombia, en el marco del proyecto “Análisis y monitoreo de los procesos de extradición de nacionales colombianos a los Estados Unidos de América”.Introducción Sobre el proceso de investigación: breve mención de la metodología Antecedentes: la extradición como mecanismo de lucha contra las drogas La extradición como institución jurídica Caracterización de las solicitudes y los conceptos de extradición, periodo 2010-2014 Sobre las solicitudes de extradición con Estados Unido

Latin American elites and armed forces: a tale of ideology and trust

Ideology is not always enough to predict trust in the armed forces, and potentially in other institutions. Over time, elites have changed their views towards the military and the evolution of trust varies. Countries that have had moderate left-wing parties in power have narrowed the ideological gap in terms of trust in the armed forces, found Cristian Márquez Romo (Universidad de Salamanca) and Xavier Romero Vidal (University of Cambridge)

On a nonlinear rod exhibiting only axial and bending deformations: mathematical modeling and numerical implementation

In this work, we present the mathematical formulation and the numerical implementation of a new model for initially straight, transversely isotropic rods. By adopting a configuration space that intrinsically avoids shear deformations and by systemically neglecting the energetic contribution due to torsion, the proposed model admits an unconstrained variational statement. Moreover, as the natural state of the rod is the trivial one and the mechanical properties are homogeneous on the cross section, the need for pull-back and push-forward operations in the formulation is totally circumvented. These features impose, however, some smoothness requirements on the stored energy function that need to be carefully considered when adopting general constitutive models. In addition to introducing the rod model, we propose a spatial discretization with the finite element method, and a time integration with a hybrid, implicit scheme. To illustrate the favorable features of the new model, we provide results corresponding to numerical simulations for plane and three-dimensional problems that are investigated in the static and dynamic settings. Finally, and to put the presented ideas in a suitable context, we compare solutions obtained with the new model against a rod model that allows for torsion and shear.publishedVersio

The Rotating Rigid Body Model Based on a Non-twisting Frame

This work proposes and investigates a new model of the rotating rigid body based on the non-twisting frame. Such a frame consists of three mutually orthogonal unit vectors whose rotation rate around one of the three axis remains zero at all times and, thus, is represented by a nonholonomic restriction. Then, the corresponding Lagrange–D’Alembert equations are formulated by employing two descriptions, the first one relying on rotations and a splitting approach, and the second one relying on constrained directors. For vanishing external moments, we prove that the new model possesses conservation laws, i.e., the kinetic energy and two nonholonomic momenta that substantially differ from the holonomic momenta preserved by the standard rigid body model. Additionally, we propose a new specialization of a class of energy–momentum integration schemes that exactly preserves the kinetic energy and the nonholonomic momenta replicating the continuous counterpart. Finally, we present numerical results that show the excellent conservation properties as well as the accuracy for the time-discretized governing equations. © 2020, The Author(s)

RefereeTrainer, app de soporte a la preparación física de árbitros de fútbol: Estudio de viabilidad.

Los árbitros de fútbol requieren entrenamientos específicos que les permitan adquirir la condición física adecuada para afrontar sus tareas durante los partidos de manera eficiente. Desde la aparición de los dispositivos móviles, se han desarrollado multitud de aplicaciones para la monitorización y gestión de rutinas de entrenamiento. En este trabajo se presenta un estudio de viabilidad de una app específica para árbitros de fútbol. Para ello, se han empleado una combinación de técnicas mediante un método mixto de investigación. A pesar de que los potenciales usuarios se han mostrado muy interesados en este tipo de aplicaciones, en la actualidad no existe ninguna solución para ellos