Particle collisions near a three-dimensional warped AdS black hole

In this paper we consider the warped AdS$_{3}$ black hole solution of topologically massive gravity with a negative cosmological constant, and we investigate the possibility that it acts as a particle accelerator by analyzing the energy in the center of mass (CM) frame of two colliding particles in the vicinity of its horizon, which is known as the Ba\~nados, Silk and West (BSW) process. Mainly, we show that the critical angular momentum $(L_c)$ of the particle decreases when the parameter that controls the stretching deformation ($\nu$) increases. Also, we show that despite the particle with $L_c$ can exist for certain values of the conserved energy outside the horizon, it will never reach the event horizon; therefore, the black hole can not act as a particle accelerator with arbitrarily high CM energy on the event horizon. However, such particle could also exist inside the outer horizon being the BSW process possible on the inner horizon. On the other hand, for the extremal warped AdS$_{3}$ black hole, the particle with $L_c$ and energy $E$ could exist outside the event horizon and the CM energy blows up on the event horizon if its conserved energy fulfill the condition $E^{2}>\frac{(\nu^{2}+3)l^{2}}{3(\nu^{2}-1)}$, being the BSW process possible.Comment: 11 pages, 6 figure

Fermionic greybody factors of two and five-dimensional dilatonic black holes

We study fermionic perturbations in the background of a two and five-dimensional dilatonic black holes. Then, we compute the reflection and transmission coefficients and the absorption cross section for fermionic fields, and we show numerically that the absorption cross section vanishes in the low and high frequency limit. Also we find that beyond a certain value of the horizon radius $r_0$ the absorption cross section for five-dimensional dilatonic black hole is constant. Besides, we have find that the absorption cross section decreases for higher angular momentum, and it decreases when the mass of the fermionic field increases.Comment: Accepted in EPJ

Origin of coherent structures in a discrete chaotic medium

Using as an example a large lattice of locally interacting Hindmarsh-Rose chaotic neurons, we disclose the origin of ordered structures in a discrete nonequilibrium medium with fast and slow chaotic oscillations. The origin of the ordering mechanism is related to the appearance of a periodic average dynamics in the group of chaotic neurons whose individual slow activity is significantly synchronized by the group mean field. Introducing the concept of a "coarse grain" as a cluster of neuron elements with periodic averaged behavior allows consideration of the dynamics of a medium composed of these clusters. A study of this medium reveals spatially ordered patterns in the periodic and slow dynamics of the coarse grains that are controlled by the average intensity of the fast chaotic pulsation

Relajación paramagnética

Se presenta una formulación unificada de la relajación longitudinal y transversal, del sistema spin-fonon, basada en la misma técnica usada previamente por R. Hernández y M. B. Walker para analizar la relajación longitudinal. La formulación tiene como objetivo presentar los resultados mediante una ecuación deducida por Redfield usando el método de la matriz densidad. Sin embargo, el presente trabajo es una deducción microscópica de la ecuación de Redfield, es decir, se determina explícitamente la matriz de relajación de la ecuación de Redfield como función de los parámetros del sistema considerado.&nbsp

Sabiduría e ignorancia del fuego

La segunda quincena del pasado mes de diciembre estuvo envuelta en llamas. Los datos oficiales registraron 396 incendios en Cantabria y 453 en Asturias, unas cifras altas, pero que no calibran la gravedad de la superficie quemada, que ronda las 10 000 ha en cada uno de los territorios afectados. Estos hechos conmocionaron a la opinión pública y, sin profundizar en las causas estructurales que hay que analizar, conocer y solucionar para evitar estas situaciones, mucho de lo que se dijo buscaba simplemente identificar a posibles culpables

Dielectric Function of Diluted Magnetic Semiconductors in the Infrared Regime

We present a study of the dielectric function of metallic (III,Mn)V diluted magnetic semiconductors in the infrared regime. Our theoretical approach is based on the kinetic exchange model for carrier induced (III,Mn)V ferromagnetism. The dielectric function is calculated within the random phase approximation and, within this metallic regime, we treat disorder effects perturbatively and thermal effects within the mean field approximation. We also discuss the implications of this calculations on carrier concentration measurements from the optical f-sum rule and the analysis of plasmon-phonon coupled modes in Raman spectra.Comment: 6 pages, 6 figures include

Sobre el proceso de formalización legislativa de las peculiaridades jurídico-civiles de Galicia

[Resumen] En este estudio se realiza un análisis del iter histórico seguido en la Comunidad gallega hasta conseguir la formalización y consolidación legislativa del Derecho privado propio de Galicia, haciendo para ello referencia a las diversas Disposiciones legales y administrativas, Memorias, Propuestas normativas, Anteproyectos, Proyectos y Proposiciones de Ley que, respectiva y sucesivamente, condujeron a las normas legislativas básicas del Derecho civil gallego en que se fueron concretando las peculiaridades jurídico-civiles –fundamentalmente de carácter consuetudinario- existentes en Galicia: la Compilación del Derecho civil Especial de Galicia , de 2 de diciembre de 1963; la Ley del Parlamento de Galicia sobre la Compilación del Derecho civil de Galicia, de 10 de noviembre de 1987; la Ley 4/1995, de 24 de mayo, de Dereito civil de Galicia; y la nueva Ley de Dereito civil de Galicia de 2006.[Abstract] This research contains an analysis of the historical path continued in the Autonomous Community of Galicia untill obtaining the legislative formalization and consolidation of its own private Law of Galicia. It shows the several legal and administratives Orders, Reports, Draft bills, and Bills, which led up to the legislative Basic Norms –Acts- of the Galician Civil Law, in which are specified the juridical-civil peculiarities –customs, mainly- existing in Galicia: Compilación del Derecho civil Especial de Galicia; Ley del Parlamento de Galicia sobre la Compilación del Derecho civil de Galicia; Ley 4/1995, de 24 de mayo, de Dereito civil de Galicia; and the new Ley de Dereito civil de Galicia (2006)