Rudiments of Holography

An elementary introduction to Maldacena's AdS/CFT correspondence is given, with some emphasis in the Fefferman-Graham construction. This is based on lectures given by one of us (E.A.) at the Universidad Autonoma de Madrid.Comment: 60 pages, additional misprints corrected, references adde

Lexical and phonological processing in visual word recognition by stuttering children: Evidence from Spanish

A number of studies have pointed out that stuttering-like disfluencies could be the result of failures in central and linguistic processing. The goal of the present paper is to analyze if stuttering implies deficits in the lexical and phonological processing in visual word recognition. This study compares the performance of 28 children with and without stuttering in a standard lexical decision task in a transparent orthography: Spanish. Word frequency and syllable frequency were manipulated in the experimental words. Stutterers were found to be considerably slower (in their correct responses) and produced more errors than the non- stutterers (?(1) = 36.63, p and lt;.001, ?2 =.60). There was also a facilitation effect of syllable frequency, restricted to low frequency words and only in the stutterers group (t1(10) = 3.67, p and lt;.005; t2(36) = 3.10, p and lt;.001). These outcomes appear to suggest that the decoding process of stutterers exhibits a deficit in the interface between the phonological-syllabic level and the word level. Copyright © Universidad Complutense de Madrid and Colegio Oficial de Psicólogos de Madrid 2014

Structural properties of various sodium thiogermanate glasses through DFT-based molecular dynamics simulations

We present a study of the structural properties of (x)Na$_2$S-(1-x)GeS$_2$ glasses through DFT-based molecular dynamics simulations, at different sodium concentrations ($0<x<0.5$). We computed the radial pair correlation functions as well as the total and partial structure factors. We also analyzed the evolution of the corner- and edge-sharing intertetrahedral links with the sodium concentration and show that the sodium ions exclusively destroy the former. With the increase of the sodium concentration the ``standard'' FSDP disappears and a new pre-peak appears in the structure factor which can be traced back in the Na-Na partial structure factor. This self organization of the sodium ions is coherent with Na-rich zones that we find at high modifier concentration.Comment: 9 pages, 7 figures; to be published in Phys. Rev.

The Dirichlet Obstruction in AdS/CFT

The obstruction for a perturbative reconstruction of the five-dimensional bulk metric starting from the four-dimensional metric at the boundary,that is, the Dirichlet problem, is computed in dimensions $6\leq d\leq 10$ and some comments are made on its general structure and, in particular, on its relationship with the conformal anomaly, which we compute in dimension $d=8$.Comment: 13 pages, references added (this paper supersedes hep-th/0206140, "A Note on the Bach Tensor in AdS/CFT", which has been withdrawn

The optimal method to make inferences about a linear combination of proportions

Asymptotic inferences about a linear combination of K independent binomial proportions are very frequent in applied research. Nevertheless, until quite recently research had been focused almost exclusively on cases of K≤2 (particularly on cases of one proportion and the difference of two proportions). This article focuses on cases of K>2, which have recently begun to receive more attention due to their great practical interest. In order to make this inference, there are several procedures which have not been compared: the score method (S0) and the method proposed by Martín Andrés et al. (W3) for adjusted Wald (which is a generalization of the method proposed by Price and Bonett) on the one hand and, on the other hand, the method of Zou et al. (N0) based on the Wilson confidence interval (which is a generalization of the Newcombe method). The article describes a new procedure (P0) based on the classic Peskun method, modifies the previous methods giving them continuity correction (methods S0c, W3c, N0c and P0c, respectively) and, finally, a simulation is made to compare the eight aforementioned procedures (which are selected from a total of 32 possible methods). The conclusion reached is that the S0c method is the best, although for very small samples (n i ≤ 10, ∀ i) the W3 method is better. The P0 method would be the optimal method if one needs a method which is almost never too liberal, but this entails using a method which is too conservative and which provides excessively wide CIs. The W3 and P0 methods have the additional advantage of being very easy to apply. A free programme which allows the application of the S0 and S0c methods (which are the most complex) can be obtained at http://www.ugr.es/local/bioest/Z_LINEAR_K.EXE

Strain balanced quantum posts

Quantum posts are assembled by epitaxial growth of closely spaced quantum dot layers, modulating the composition of a semiconductor alloy, typically InGaAs. In contrast with most self-assembled nanostructures, the height of quantum posts can be controlled with nanometer precision, up to a maximum value limited by the accumulated stress due to the lattice mismatch. Here we present a strain compensation technique based on the controlled incorporation of phosphorous, which substantially increases the maximum attainable quantum post height. The luminescence from the resulting nanostructures presents giant linear polarization anisotropy.Comment: Submitted to Applied Physics Letters (7th March 2011). 4 pages, 4 figure

Determination of Network Configuration Considering Inventory Cost in a Supply Chain

AbstractIn this paper we show the importance of applying mathematical optimization when designing the distribution network in a supply chain, specifically in making decisions related location of facilities and inventory management, which are associated with different levels of planning but are closely related.The addressed problem is an extension of the classic capacitated facility location problem. The distinguishing features are: the inventory management, the presence of multiple plants, and the single source constraints in both echelons. A key issue is that demand at each distribution center is a function of the demands at the retailers assigned, which is a random variable whose value is not known at the time of designing the network. We focus on the mathematical modeling of the problem and the evaluation of the performance of the developed models, so, it can be observed the troubles that arise when modeling supply chains that consider different types of decisions

Validation of the Satisfaction Scale of Basic Psychological Needs in Physical Education with the Incorporation of the Novelty in the Spanish Context

The purpose of the study was to validate to the physical education context, the Spanish version of the Scale of the Satisfaction of Psychological Needs toward the Physical Education classes of Menéndez and Fernández-Rio, with the incorporation of the novelty, since they contemplated its inclusion. In this study, 1444 students participated (mean = 15.34, standard deviation = 1.12) from several schools in Almeria. To analyze the psychometric properties of the scale, several analyses were carried out. The results offered support for both the four-factor structure and the higher-order model called satisfaction. The analysis of invariance with respect to gender showed that the factor structure of the questionnaire was invariant. The Cronbach alpha values were higher than 0.70 in the subscales. The results of this study demonstrated the reliability and validity of the Scale of the Satisfaction of Psychological Needs, with the incorporation of novelty in the Spanish context of Physical Education