Perturbative contributions to Wilson loops in twisted lattice boxes and reduced models

We compute the perturbative expression of Wilson loops up to order $g^4$ for SU($N$) lattice gauge theories with Wilson action on a finite box with twisted boundary conditions. Our formulas are valid for any dimension and any irreducible twist. They contain as a special case that of the 4-dimensional Twisted Eguchi-Kawai model for a symmetric twist with flux $k$. Our results allow us to analyze the finite volume corrections as a function of the flux. In particular, one can quantify the approach to volume independence at large $N$ as a function of flux $k$. The contribution of fermion fields in the adjoint representation is also analyzed.Comment: pdflatex 57 pages, 9 figures, 4 appendice

A multivariate generalized independent factor GARCH model with an application to financial stock returns

We propose a new multivariate factor GARCH model, the GICA-GARCH model , where the data are assumed to be generated by a set of independent components (ICs). This model applies independent component analysis (ICA) to search the conditionally heteroskedastic latent factors. We will use two ICA approaches to estimate the ICs. The first one estimates the components maximizing their non-gaussianity, and the second one exploits the temporal structure of the data. After estimating the ICs, we fit an univariate GARCH model to the volatility of each IC. Thus, the GICA-GARCH reduces the complexity to estimate a multivariate GARCH model by transforming it into a small number of univariate volatility models. We report some simulation experiments to show the ability of ICA to discover leading factors in a multivariate vector of financial data. An empirical application to the Madrid stock market will be presented, where we compare the forecasting accuracy of the GICA-GARCH model versus the orthogonal GARCH one

Democedes de Crotona : biografía de un médico de finales del siglo VI a.C.

La biografía de Democedes presente en la Historia de Herodotus constituye un documento esencial para conocer la situación de la medicina griega de finales del siglo VI a.C., así como el papel que los médicos desempeñaban en el seno de la sociedad. Aunque Heródoto no proporciona una datación cronológica precisa, se puede establecer una correlación cronológica aproximada de la vida de Democedes.The biography of Democedes, present in the History of Herodotus, constitutes an essential document to know the situation of the Greek medicine of final of the century VI B.C., as well as for the paper that the doctors carried out in the breast of the society. Although Herodotus doesn’t provide a precise chronology, an approximate chronological correlation of the life of Democedes can settle establish

La heroificación taurina. El caso de Sánchez Mejías

Ignacio Sánchez Mejías. Periodista y dramaturgo. Seminari

La circunnavegación de "Libia" : entre mito y realidad

En los inicios de la corriente de pensamiento y experiencias que abren el camino para llegar a la geografía científica, junto al desarrollo teórico elaborado por los llamados “físicos jonios”, encontramos una serie de empresas oceánicas que venían a confirmar en parte tales planteamientos. El caso de la circunnavegación de África que nos presenta Heródoto constituye un ejemplo paradigmático de este tipo de expedicionesIn the beginnings of the current of thought and experiences that open the way to come to the scientific geography, along with the theoretical development prepared by the so-called “ionic physicists”, we find a series of oceanic companies that were coming to confirm partly such expositions. The case of the circumnavigation of Africa that Herodotus presents to us constitutes a paradigmatic example of this type of expedition

La Industria algodonera catalana y el libre comercio : otra reconsideración

El papel desempeñado por el mercado americano en el proceso industrializador catalán ha constituido un elemento clave de discusión historiográfica en los últimos años. Con el presente artículo, el profesor García-Baquero añade nuevos elementos documentales a la reflexión histórica y valora positivamente la importancia que el comercio con América tuvo en el desarrollo de la industria textil catalana en las últimas décadas del Setecientos.The role played by the American market in the catalan industrializing process has been a key subject of historiographic discussion in the last years. With the present article, professor García Baquero adds new documentary elements to the historical reflection and values in a positive way the importance that had the commerce with America for the development of the Catalan textile industry in the last decades of the Eighteenth centur