Historia verdadera, y lamentable de los siete Infantes de Lara con la de Mudarra Gonzalez, su hermano, ...

Sig. : A-C

Determination of the glass-forming concentration range in binary alloys from a semiempirical theory: Application to Zr-based alloys

Producción CientíficaA semiempirical theory is presented to calculate free-energy diagrams of glass-forming alloys. The theory is based on the enthalpy of formation of the solid solution expressed as a sum of two contributions: (a) a chemical contribution due to electronic redistribution in forming the alloy, and (b) an elastic contribution arising from the difference in size between solute and solvent atoms. The enthalpy of formation of the amorphous phase has only the chemical contribution. The theory is used to successfully describe the glass-forming concentration range of some Zr-based alloys, which have been experimentally analyzed by several distinct techniques

Validación de la versión espanola de la escala multidimensional de orientaciones a la deportividad

The aim of this study was to translate into Spanish and validate the Multidimensional Sportspersonship Orientations Scale (MSOS), which was developed in English and validated by Vallerand et al. (1997). The MSOS consistsof five subscales that measure full commitment toward sport, respect for social conventions, respect and concern for rules and officials, respect and concern for opponents, and negative approach towards sportspersonship. The Spanish version of the scale showed acceptable levels of internal consistency and temporal stability over a four-week period. The results of a confirmatory factor analysis confirmed the five-factor structure of the MSOS. Correlations among the subscales confirmed the scales construct validity. Finally, gender differences were obtained. These findings support the use of the Spanish version of the MSOS for assessing individual differences in sportspersonship orientations

Identity profile of young people experiencing a sense of risk on the internet: a data mining application of decision tree with CHAID algorithm

[EN]Social media, interactive games, and digital platforms are just some of the ways in which the internet has become part of our lives, and more specifically so among young people. Among other things, this technology is the reason young people are spending increasingly more time online than offline, prompting numerous risks that they are sometimes unaware of. The following quantitative research is based on this premise, and it pursues two objectives, namely, to discover whether or not young people experience a sense of risk linked to their use of the internet and identify the kind of young people that say they do or do not perceive any such risk. A total of 1991 young people answered the Technology Use Studies questionnaire. The classification tree technique based on the Chi-square Automatic Interaction Detector (CHAID) was applied to identify the predictive variables associated with the sense of risk in young people. Two highly significant results have been forthcoming: firstly, we present the factors with the biggest impact on a young person's internet-related sense of risk, involving isolation when they cannot go online, followed by variables such as gender, the use of TikTok, and videogames, the consumption of pornography, and distraction from study time. Secondly, our results indicate that the young people that feel isolated when they cannot go online are precisely the ones that do not experience a sense of online risk. It is therefore of vital importance for education to generate and provide young people with strategies that allow them to establish a healthy and responsible relationship with technologies such as the internet

A Clustering Algorithm Based on an Ensemble of Dissimilarities: An Application in the Bioinformatics Domain

Clustering algorithms such as k-means depend heavily on choosing an appropriate distance metric that reflect accurately the object proximities. A wide range of dissimilarities may be defined that often lead to different clustering results. Choosing the best dissimilarity is an ill-posed problem and learning a general distance from the data is a complex task, particularly for high dimensional problems. Therefore, an appealing approach is to learn an ensemble of dissimilarities. In this paper, we have developed a semi-supervised clustering algorithm that learns a linear combination of dissimilarities considering incomplete knowledge in the form of pairwise constraints. The minimization of the loss function is based on a robust and efficient quadratic optimization algorithm. Besides, a regularization term is considered that controls the complexity of the distance metric learned avoiding overfitting. The algorithm has been applied to the identification of tumor samples using the gene expression profiles, where domain experts provide often incomplete knowledge in the form of pairwise constraints. We report that the algorithm proposed outperforms a standard semi-supervised clustering technique available in the literature and clustering results based on a single dissimilarity. The improvement is particularly relevant for applications with high level of noise

Collective electronic excitations in metal-coated C_60

Producción CientíficaA two-shell jellium-on-jellium model has been used to study the collective electronic excitations of C_60 coated by an increasing number N of Na atoms. We predict a transition from the π-electron polarization of the fullerene to the metallic sodium polarization as a function of increasing N. For low coverages, the Na layer produces only a broadening and fragmentation of the π plasmon of C_60. However, if the coverage is large enough, a Na surface plasmon appears. This occurs only after the electron density of the cluster clearly shows two distinct regions, the outer one having an ‘‘average’’ density similar to that in pure Na metal or Na clusters. The induced density at the collective-mode frequency shows structure corresponding to two interfaces, C_(60-)Na and Na vacuum, the first peak becoming less pronounced as the coverage increases due to a transfer of oscillator strength to the metallic counterpart. The static polarizability per electron also shows this trend and tends slowly to the Na value from below after an initial sharp rise in the region N∼13–21

Evaluating Urban Regeneration Policies. Methodological Proposal to Delimitate Experimental and Equivalent Urban Areas

El presente artículo presenta una propuesta metodológica para la delimitación de áreas territoriales aplicando una estrategia de corte cuasi-experimental, comparando las áreas en las que se ha desarrollado algún proyecto de regeneración urbana llamadas “áreas experimentales” con otras similares en las que no se ha desarrollado ningún proyecto, denominadas “áreas equivalentes”. Esta metodología es el paso previo necesario para el análisis de los efectos de los programas de regeneración urbana, que permitirá posteriormente comparar la evolución en el tiempo de pares semejantes entre sí (área experimental y área equivalente). En primer lugar, se explica el objetivo que subyace a la delimitación de estas áreas territoriales. En segundo lugar, se describe la metodología utilizada para seleccionar las áreas equivalentes. En tercer lugar, se presentan los resultados, esto es, la delimitación de áreas experimentales y equivalentes. . Por último, mediante procedimientos estadísticos concretos, análisis de varianza o ANOVA de un factor, se validan los resultados obtenidos. El trabajo se centra en las ciudades andaluzas de más de 100 mil habitantes en las que se han ejecutado proyectos de regeneración urbana.This article analyses a methodological proposal for the delimitation of territorial areas applying a quasi-experimental strategy, comparing areas where projects have been developed based in urban regeneration called “experimental areas” with similar ones without any project, called “equivalent areas”. This methodology is a necessary previous step to analyze the effect of programs about urban regeneration, which will allow subsequently to compare the evolution of similar pairs among themselves (experimental and equivalent areas). Firstly, we explain the underlying objective of delimitation in these territorial areas. Secondly, the methodology used to select the equivalent areas is described. Thirdly, the results are presented, it means, the delimitation of experimental and equivalent areas. Finally, through means of specific statistical procedures, analysis of variance or ANOVA of a factor, the obtained results are validated. The work is focused on Andalusian cities with a population over 100.000 inhabitants in which urban regeneration projects have been implemented.Consejería de Fomento y Vivienda de la Junta de Andalucía GGI30011/DIYFEDER GGI30011/DI

Structure and bonding in small neutral alkali halide clusters

Producción CientíficaThe structural and bonding properties of small neutral alkali halide clusters, (AX)_n with n<10, A=Li^+,Na^+,K^+,Rb^+, and X=F^-,Cl^-,Br^-,I^-, are studied using the ab initio perturbed ion (PI) model and a restricted structural relaxation criterion. A trend of competition between rocksalt and hexagonal ringlike isomers is found and discussed in terms of the relative ionic sizes. The main conclusion is that an approximate value of r_C /r_A=0.5 (where r_C and r_A are the cationic and anionic radii) separates the hexagonal from the rocksalt structures. The classical electrostatic part of the total energy at the equilibrium geometry is enough to explain these trends. The magic numbers in the size range studied are n=4, 6, and 9, and these are universal since they occur for all alkali halides and do not depend on the specific ground-state geometry. Instead those numbers allow for the formation of compact clusters. Full geometrical relaxations are considered for (LiF)_n (n=3 – 7) and (AX)_3 clusters, and the effect of Coulomb correlation is studied in a few selected cases. These two effects preserve the general conclusions achieved thus far

Eating disorders

[EN] Eating disorders (EDs) are an important public health problem in developed countries. Despite the amount of epidemiological studies and causal theories, there is a great disparity of estimates and many questions remain still unclear. The aim of this study was to estimate the prevalence of the population at risk of developing EDs and describe the risk profiles among adolescents and young people. Methods A transversal design using a twostage cluster sample of secondary education students aged between 12 and 18 years was used. The survey consisted of a socio-demographic questionnaire along with the Eating Attitudes Test (EAT)-40 index and was carried out between May and June 1999. Results Results showed that 7.8% of the secondary school population had a high risk of developing eating disorders (EAT-40 higher than 30). Females presented a higher percentage [12.3%; 95% confidence limits (CL) 10.4–14.3%] than males (3.2%; 95% CL 2.1–4.2%) at the highest risk levels. A decreasing risk gradient was observed with age. Conclusions The estimates show an important difference between the risk in females and in males and suggests that the risk is incremented above all in the last few years of infancy and the first years of adolescence, when these boys and girls are more vulnerable to socio-cultural influences and do not yet have defined image and “behaviour models.

II Congreso Internacional de la Asociación Hispánica de Literatura Medieval (Segovia, del 5 al 19 de Octubre de 1987)

Producción CientíficaDesde que en el siglo XV se atribuyera por primera vez el Libro de la montería a Alfonso XI hasta hoy día, no ha habido centuria en la que no se haya planteado la cuestión de la autoría. Cuestión que se puede dividir en dos etapas muy diferenciadas: siglos XV-XVII de atribución sin discusión a Alfonso XI, aunque, como se verá en su momento, hubo quien rompió, por error o conscientemente, una lanza a favor de Alfonso X. Y una segunda época: siglos XVIII-XX en los que se entabla la discusión, que no se inicia con José Amador de los Ríos, sino cuando Francisco Javier de Santiago y Palomares fue comisionado por Godoy para hacer una edición de esta obra. El título de mi comunicación es elocuente, dice claramente y sin ningún lugar a dudas qué es lo que pretendo: hacer la historia y comentario de seiscientos años de discusión y tratar de llegar a una conclusión válida que pueda poner fin a tan larga controversia, si es que esto es posible. Procederé cronológicamente, empezando por lo que dicen al respecto los doce manuscritos conservados^, para finalizar con los más recientes estudios