Conductivity and entanglement entropy of high dimensional holographic superconductors

We investigate the dependence of the conductivity and the entanglement entropy on the space-time dimensionality $d$ in two holographic superconductors: one dual to a quantum critical point with spontaneous symmetry breaking, and the other modeled by a charged scalar that condenses at a sufficiently low temperature in the presence of a Maxwell field. In both cases the gravity background is asymptotically Anti de Sitter (AdS). In the large $d$ limit we obtain explicit analytical results for the conductivity at zero temperature and the entanglement entropy by a $1/d$ expansion. We show that the entanglement entropy is always smaller in the broken phase. As dimensionality increases, the entanglement entropy decreases, the coherence peak in the conductivity becomes narrower and the ratio between the energy gap and the critical temperature decreases. These results suggest that the condensate interactions become weaker in high spatial dimensions.Comment: 38 pages, 7 figure

Regularization dependence of the OTOC. Which Lyapunov spectrum is the physical one?

We study the contour dependence of the out-of-time-ordered correlation function (OTOC) both in weakly coupled field theory and in the Sachdev-Ye-Kitaev (SYK) model. We show that its value, including its Lyapunov spectrum, depends sensitively on the shape of the complex time contour in generic weakly coupled field theories. For gapless theories with no thermal mass, such as SYK, the Lyapunov spectrum turns out to be an exception; their Lyapunov spectra do not exhibit contour dependence, though the full OTOCs do. Our result puts into question which of the Lyapunov exponents computed from the exponential growth of the OTOC reflects the actual physical dynamics of the system. We argue that, in a weakly coupled $\Phi^4$ theory, a kinetic theory argument indicates that the symmetric configuration of the time contour, namely the one for which the bound on chaos has been proven, has a proper interpretation in terms of dynamical chaos. Finally, we point out that a relation between these OTOCs and a quantity which may be measured experimentally --- the Loschmidt echo --- also suggests a symmetric contour configuration, with the subtlety that the inverse periodicity in Euclidean time is half the physical temperature. In this interpretation the chaos bound reads $\lambda \leq \frac{2\pi}{\beta}= \pi T_{\text{physical}}$.Comment: Comment on regularization dependence in 2d-CFTs added. Published versio

La red española de desarrollo rural (R.E.D.R.)

En este trabajo se exponen diversas cuestiones relativas a la creación, evolución, objetivos, fines, prioridades y áreas de actuación de la Red Española de Desarrollo Rural, organización no gubernamental constituida en 1995 con el objetivo genérico de promover un modelo de desarrollo rural integral y sostenible. De igual modo, se realiza una valoración del período de programación 2007-2013, con especial referencia a la futura Ley de Desarrollo Rural Sostenible y al futuro de los Grupos de Desarrollo tras la aprobación del Reglamento FEADER.In this work, there are several exposed problems related to the creation, evolution, goals, aims, priorities and performance areas of the Spanish Net of Rural Development, a non-governmental organization constituted in 1995 with the generic aim of promoting a model of sustainable and integral rural development. On the same hand, it has accomplished a valuation of the period of programming 2007-2013, with special reference to the future Law of Sustainable Rural Development and to the future of the Groups of Development after the approval of the Regulation of the Agrarian European Fund of Rural Development (FEADER)

A Cardy formula for off-diagonal three-point coefficients; or, how the geometry behind the horizon gets disentangled

In the AdS/CFT correspondence eternal black holes can be viewed as a specific entanglement between two copies of the CFT: the thermofield double. The statistical CFT Wightman function can be computed from a geodesic between the two boundaries of the Kruskal extended black hole and therefore probes the geometry behind the horizon. We construct a kernel for the AdS3/CFT2 Wightman function that is independent of the entanglement. This kernel equals the average off-diagonal matrix element squared of a primary operator. This allows us to compute the Wightman function for an arbitrary entanglement between the double copies and probe the emergent geometry between a left- and right-CFT that are not thermally entangled.Comment: 18 pages, 8 figures v2: Added appendix on spatial dependence, minor changes, matches published versio

Design Optimization of the Aeronautical Sheet Hydroforming Process Using the Taguchi Method

The aluminium alloy sheet forming processes forging in rubber pad and diaphragm presses (also known as hydroforming processes) are simple and economical processes adapted to aeronautical production. Typical defects of these processes are elastic recovery, necking, and wrinkling, and they present di culties in control mainly due to property variations of the sheet material that take place during the process. In order to make these processes robust and unresponsive to material variations, a multiobjective optimization methodology based on the Taguchi method is proposed in the present study. The design of experiments and process simulation are combined in the methodology, using the nonlinear finite element method. The properties of sheet material are considered noise factors of the hydroforming process, the objective being to find a combination of the control factors that causes minimal defects to noise factors. The methodology was applied to an AA2024-T3 aluminium alloy sheet of 1 mm thickness stamping process in a diaphragm press. The results allowed us to establish the optimal pressure values, friction coeficient between sheet and block, and friction coeficient between sheet and rubber to reduce the elastic recovery variations and the minimal thickness before noise facts

La red española de desarrollo rural (R.E.D.R.)

En este trabajo se exponen diversas cuestiones relativas a la creación, evolución, objetivos, fines, prioridades y áreas de actuación de la Red Española de Desarrollo Rural, organización no gubernamental constituida en 1995 con el objetivo genérico de promover un modelo de desarrollo rural integral y sostenible. De igual modo, se realiza una valoración del período de programación 2007-2013, con especial referencia a la futura Ley de Desarrollo Rural Sostenible y al futuro de los Grupos de Desarrollo tras la aprobación del Reglamento FEADER.In this work, there are several exposed problems related to the creation, evolution, goals, aims, priorities and performance areas of the Spanish Net of Rural Development, a non-governmental organization constituted in 1995 with the generic aim of promoting a model of sustainable and integral rural development. On the same hand, it has accomplished a valuation of the period of programming 2007-2013, with special reference to the future Law of Sustainable Rural Development and to the future of the Groups of Development after the approval of the Regulation of the Agrarian European Fund of Rural Development (FEADER)

Diseño de mecanismos eficientes para la gestión de subredes infiniband

El objetivo principal de esta tesis doctoral es contribuir al desarrollo de mecanismos de asimilación de cambios toplogicos para la arquitectura de red infiniband. En una primera fase, se ha diseñado y evaluado un primer prototipo de mecanismo de gestión. Su evaluación nos ha permitido identificar los principales cuellos de botella en el proceso de adaptación al cambio. A continuación, se han propuesto mecanismos optimizados para cada una de las tareas involucradas en dicho proceso: la detección del cambio topológico, la adquisición de la nueva topología de la red, el cómputo de nuevas rutas y la distribución de tables de encaminamiento actualizadas a los conmutadores de la red. El resultado es un mecanismo de gestión totalmente compatible con la especificación de infiniband, fácilmente implementable en sistemas comerciales, y casi transparente desde el punto de vista de las aplicaciones a las que da servicio la red