Two-dimensional models of early-type fast rotating stars: new challenges in stellar physics

Two-dimensional models of rapidly rotating stars are already unavoidable for the interpretation of interferometric or asteroseismic data of this kind of stars. When combined with time evolution, they will allow the including of a more accurate physics for the computation of element transport and the determination of surface abundances. In addition, modeling the evolution of rotation will improve gyrochronology. Presently, two-dimensional ESTER models predict the structure and the large-scale flows (differential rotation and meridional circulation) of stars with mass larger than 1.7Msun at any rotation rate. Main sequence evolution can be mimicked by varying the hydrogen content of the convective core. Models have been successfully tested on half a dozen of nearby fast rotating stars observed with optical or infra-red interferometers. They are now the right tool to investigate the oscillation spectrum of early-type fast rotators.Comment: 10 pages, to appear in the proceedings of the conference "New advances in stellar physics: from microscopic to macroscopic processes", Roscoff, May 201

Gravity Darkening in Binary Stars

Context.Interpretation of light curves of many types of binary stars requires the inclusion of the (cor)relation between surface brightness and local effective gravity. Until recently, this correlation has always been modeled by a power law relating the flux or the effective temperature and the effective gravity, namely T_eff {\alpha} g_eff^{\beta}. Aims. We look for a simple model that can describe the variations of the flux at the surface of stars belonging to a binary system. Methods. This model assumes that the energy flux is a divergence-free vector anti-parallel to the effective gravity. The effective gravity is computed from the Roche model. Results. After explaining in a simple manner the old result of Lucy (1967), which says that {\beta}=0.08 for solar type stars, we first argue that one-dimensional models should no longer be used to evaluate gravity darkening laws. We compute the correlation between log T_eff and log g_eff using a new approach that is valid for synchronous, weakly magnetized, weakly irradiated binaries. We show that this correlation is approximately linear, validating the use of a power law relation between effective temperature and effective gravity as a first approximation. We further show that the exponent {\beta} of this power law is a slowly varying function, which we tabulate, of the mass ratio of the binary star and the Roche lobe filling factor of the stars of the system. The exponent {\beta} remains mostly in the interval (0.20, 0.25) if extreme mass ratios are eliminated. Conclusions. For binary stars that are synchronous, weakly magnetized and weakly irradiated, the gravity darkening exponent is well constrained and may be removed from the free parameters of the models

On the Utility of the Inverse Gamma Distribution in Modeling Composite Fading Channels

We introduce a general approach to characterize composite fading models based on inverse gamma (IG) shadowing. We first determine to what extent the IG distribution is an adequate choice for modeling shadow fading, by means of a comprehensive test with field measurements and other distributions conventionally used for this purpose. Then, we prove that the probability density function and cumulative density function of any IG-based composite fading model are directly expressed in terms of a Laplace-domain statistic of the underlying fast fading model, and in some relevant cases, as a mixture of well-known state-of-the-art distributions. We exemplify our approach by presenting a composite IG/two-wave with diffuse power fading model, for which its statistical characterization is directly attained in a simple form.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

El pasado como campo de batalla: lucha de memorias (2007-2008). De la Ley de Memoria Histórica a la iniciativa del juez Garzón

The strength of the social movement supporting the position that the victims of the military coup in July 1936 should not be consigned to oblivion finally managed to put historical memory on the political agenda, first in the elections and later in Congress after the triumph of the PSOE (Spanish Socialist Party) in 2004. However, it is the very inertia of recent history, along with the political peculiarities of the powers in the majority, which make it difficult for Spain to take on board the obscure past at the three levels that circumstances require: truth, justice and reparation. The “Law of Memory” of December 2007 constitutes a rather flimsy emergency exit for a long-standing problem which seems to have no way out. The judiciary process initiated by Judge Baltasar Garzón in September 2008, which raised such great expectations, has shown itself to be equally useless. The reality is that the big questions such as the locating and exhuming of the mass graves by the government, the pardoning of judicial-military Francoists, the anomalous situation of the military archives and the future of the Valle de los Caídos (Valley of the Fallen) continue to be pending issues. And the worst thing is that the solution is still out of sight, seventy-three years after the coup and nearly thirty-five years after the death of the dictator. Key words: Historical memory, Transition, Law of Amnesty, Judge Garzó

Can cognitive performance predict physical fitness and academic achievement one year later?

Previous studies have shown that physical activity, fitness and academic achievement might predict cognitive performance later in life . However, to the best of our knowledge, there are no studies examining the inverse relationship, that is, whether cognition may predict fitness and academic achievement in adolescents one year later . Therefore, the aim of this study was to examine the associations between cognitive performance and physical fitness and academic achievement one year later .Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech