Variational Methods in AdS/CFT

We prove that the AdS/CFT calculation of 1-point functions can be drastically simplified by using variational arguments. We give a simple universal proof, valid for any theory that can be derived from a Lagrangian, that the large radius divergencies in 1-point functions can always be renormalized away (at least in the semiclassical approximation). The renormalized 1-point functions then follow by a simple variational problem involving only finite quantities. Several examples, a massive scalar, gravity, and renormalization flows, are discussed. Our results are general and can thus be used for dualities beyond AdS/CFT.Comment: 14 pages, no figures, LaTeX, minor change in footnot

Attitudes toward immigrants: a cross-country perspective

This paper examines the foundations of attitudes towards immigrants by focusing on individual characteristics and country-specific effects. We use a micro-level data set from 31 countries. In particular, we utilize the module on National Identity of the 2003 International Social Survey Program (ISSP). Results indicate that gender, education, age, labor-market status, and political and religious affiliation are important indicators of the attitude toward immigrants. The largest effect appears to be that of education, with more education being positively correlated with a positive view of immigrants. Additionally, we find that country of residence matters.immigration, microeconomic behavior, comparative research.

Black Hole Entropy and the Dimensional Continuation of the Gauss-Bonnet Theorem

The Euclidean black hole has topology $\Re^2 \times {\cal S}^{d-2}$. It is shown that -in Einstein's theory- the deficit angle of a cusp at any point in $\Re^2$ and the area of the ${\cal S}^{d-2}$ are canonical conjugates. The black hole entropy emerges as the Euler class of a small disk centered at the horizon multiplied by the area of the ${\cal S}^{d-2}$ there.These results are obtained through dimensional continuation of the Gauss-Bonnet theorem. The extension to the most general action yielding second order field equations for the metric in any spacetime dimension is given.Comment: 7 pages, RevTe

The Black Hole in Three Dimensional Space Time

The standard Einstein-Maxwell equations in 2+1 spacetime dimensions, with a negative cosmological constant, admit a black hole solution. The 2+1 black hole -characterized by mass, angular momentum and charge, defined by flux integrals at infinity- is quite similar to its 3+1 counterpart. Anti-de Sitter space appears as a negative energy state separated by a mass gap from the continuous black hole spectrum. Evaluation of the partition function yields that the entropy is equal to twice the perimeter length of the horizon.Comment: This version is the one that appeared in PRL (1992), and has important improvements with respect to the one previously submitted to the archive. 13 pages, latex, no figure

Achievable throughput with Block Diagonalization on OFDM indoor demonstrator

The proceeding at: 21st European Signal Processing Conference (EUSIPCO 2013), took place 2013, September 09-13, in Marrakech, Septiembre 2013.Block Diagonalization (BD) is a linear precoding transmission technique able to achieve full multiplexing gain in multiple antenna systems. In this work we present a Multiple-Input Multiple-Output (MIMO) implementation based on Orthogonal Frequency Division Multiplexing (OFDM) made up of a transmitter with 4 antennas and 2 users equipped with 2 antennas each one, which allows us to evaluate the performance of BD in indoor scenarios. First, the theoretic achievable rates are obtained for the measured channel in an offline evaluation. After that, the bit error rate performance is evaluated regarding the system sum throughput. To the best of our knowledge, this is the first time that BD performance is validated using a multiuser MIMO testbed.This work has been partially funded by research projects COMONSENS (CSD2008-000 1 0), and GRE3N (TEC20 11-29006-C03-02).Publicad

Eddington-Born-Infeld action for dark energy and dark matter

We argue that Einstein gravity coupled to a Born-Infeld theory provides an attractive candidate to represent dark matter and dark energy. For cosmological models, the Born-Infeld field has an equation of state which interpolates between matter, w=0 (small times), and a cosmological constant w=-1 (large times). On galactic scales, the Born-Infeld field predicts asymptotically flat rotation curves.Comment: A sign mistake in section on galactic scales is pointed out. This sign invalidates the content of that section. See comment on manuscrip

Short communication: Occurrence of angular leaf spot caused by Pseudocercospora griseola in Phaseolus vulgaris in Asturias, Spain

Angular leaf spot (ALS) symptoms were observed in 2015 in common bean fields at four locations in Asturias, NW Spain. This disease is frequent in tropical areas and we have no record of its presence in our region, at least in the last 30 years. However, since its detection its presence in the crops has been increasing. Symptoms were necrotic spots on leaves and reddish-brown to black circular spots on pods, stems, branches and petioles. The damage observed in the mentioned crops was highly variable (between 60% and 100% affected leaves), being most severe in crops where no agrochemical treatment were applied. Three strains were selected and identified based in morphological features as Pseudocercospora griseola. The ITS region was amplified by PCR obtaining a sequence that was identical for the three isolates (Acc. No. LT222499). This sequence showed 99-100% similarity with those deposited in databases corresponding to P. griseola. To fulfill Koch's postulates, a pathogenicity test was carried out in two common bean cultivars (‘Andecha’ and ‘Maruxina’). P. griseola was re-isolated from inoculated plants and not from control plants. In cv. ‘Andecha’, chlorosis was observed in all the inoculated plants, before the appearance of spots. Consequently this is the first confirmed report of this pathogen in our region

Epistemología, caos y enseñanza de las ciencias

In this article it is maintained that modern science is going through a critical period where its epistemological assumptions and the use of a parcelling and reductionist methodology are questioned. This will surely have important implications in the teaching of the sciences, perhaps because the world today demands above all an epistemological change in the people who, within a few years, will occuppy the posts in the production and reproduction of scientific and technical knowledge

Miristato de miristilo “100% natural”. Estudio del proceso de síntesis biocatalítica

El miristato de miristilo es uno de los ésteres cerosos másutilizados en las formulaciones cosméticas como emoliente.La legislación europea permite catalogar como productosnaturales a todos aquellos obtenidos directamente dela naturaleza o los sintetizados mediante procedimientosbiocatalíticos. En este contexto, el presente trabajo recogelos estudios realizados para optimizar la síntesis biocatalíticade miristato de miristilo con lipasa de Candida antarcticainmovilizada (Novozym® 435). Operando a 70ºC, avacío y con circulación de N2 seco, se ha podido obtener,en tan sólo 2 horas, un éster que presenta las mismas características (número ácido, valor de hidroxilo, índice deyodo e índice de saponificación), que los productos quese encuentran actualmente en el mercado, con la notableventaja de que este miristato de miristilo permite el etiquetadode los productos cosméticos que lo contienen como“100% natural”

Darboux coordinates for (first order) tetrad gravity

The Hamiltonian form of the Hilbert action in the first order tetrad formalism is examined. We perform a non-linear field redefinition of the canonical variables isolating the part of the spin connection which is canonically conjugate to the tetrad. The geometrical meaning of the constraints written in these new variables is examined.Comment: 12 pages, Latex. Minor presentation changes and some references added. Version to appear in Classical and Quantum Gravit