Response of the topological surface state to surface disorder in TlBiSe2

Through a combination of experimental techniques we show that the topmost layer of the topological insulator TlBiSe2 as prepared by cleavage is formed by irregularly shaped Tl islands at cryogenic temperatures and by mobile Tl atoms at room temperature. No trivial surface states are observed in photoemission at low temperatures, which suggests that these islands cannot be regarded as a clear surface termination. The topological surface state is, however, clearly resolved in photoemission experiments. This is interpreted as direct evidence of its topological self-protection and shows the robust nature of the Dirac cone-like surface state. Our results can also help explain the apparent mass acquisition in S-doped TlBiSe2.

El modelo de Markowitz en la gestión de carteras

[ES] Desde su aparición, el modelo de Markowitz ha sido un referente teórico fundamental en la selección de carteras de valores, dando lugar a múltiples desarrollos y derivaciones. Sin embargo, su utilización en la práctica entre gestores de carteras y analistas de inversiones no ha sido tan amplia como podría esperarse de su éxito teórico. Con este trabajo pretendemos demostrar que el modelo de Markowitz puede ser de gran utilidad en la práctica. A través de un estudio empírico queremos verificar si el modelo de Markowitz es capaz de proporcionar carteras que nos ofrezcan una mayor rentabilidad y un menor riesgo que la cartera representada por los índices IBEX-35 e IGBM. Así mismo, pretendemos comprobar la supuesta eficiencia de estos índices como representantes de la cartera de mercado teórica.

Representación 3D interactiva de relaciones de derivación e hiponimia en paradigmas léxicos del inglés antiguo

Participantes en el proyecto Nerthus: Javier Martín Arista (Universidad de La Rioja, Investigador principal), Laboratorio de Documentación Geométrica del Patrimonio (Universidad del País Vasco UPV/EHU).-- Sitio web del proyecto: http://www.nerthusproject.com/

Construcción de índices simplificados de riesgo país: Aproximación a los casos de Europa y América

[ES] Partiendo de los valores semestrales de cada una de las nueve variables que componen el índice de riesgo país elaborado por Euromoney, en el periodo comprendido entre septiembre de 1992 y septiembre de 2002, para 41 países europeos y 30 países americanos, los autores proponen la construcción de dos nuevos índices de riesgo país, a los que han denominado «Índice Simplificado» e «Índice Observacional». La característica de ambos índices es que, además de contener únicamente cuatro variables (de las nueve propuestas por el índice de riesgo país de Euromoney), permiten replicar, con un elevado índice de fiabiabilidad el ranking de países (dado en función de su riesgo país) proporcionado por el índice del cual se derivan.

Los dominios social y personal del autoconcepto

[Es] El estudio del autoconcepto continúa siendo uno de los grandes retos de la investigación psicológica. Se trata de un campo de investigación muy amplio en el que tanto la dimensión física como la académica han sido objeto de numerosas investigaciones; por el contrario son pocas las investigaciones llevadas a cabo tanto sobre el autoconcepto social como sobre el autoconcepto personal. En este trabajo se informa de dos estudios llevados a cabo con el fin de verificar si los análisis factoriales confirman una estructura multidimensional de tres componentes en el caso del social (la responsabilidad social, la aceptación social y la competencia social) y de cuatro componentes en la del personal: la autorrealización, la honradez, la autonomía, y el ajuste emocional. Los resultados obtenidos a partir de la aplicación de dos cuestionarios elaborados específicamente para medir ambos dominios (APE y AUSO) confirman en buena medida esta estructura; los factores identificados explican un 52,56% y un 41,43%, respectivamente, de la varianza. Por otro lado, los índices de consistencia interna son aceptables en ambos casos: alpha 0.85 en el APE y alpha 0.76 en el AUSO. Se proponen algunos cambios a incorporar en la versión definitiva de ambos cuestionarios.

Stability of the factorial structure of metabolic syndrome from childhood to adolescence : a 6-year follow-up study

Background: Metabolic syndrome (MS) is a clustering of cardiometabolic risk factors that is considered a predictor of cardiovascular disease, type 2 diabetes and mortality. There is no consistent evidence on whether the MS construct works in the same way in different populations and at different stages in life. Methods: We used confirmatory factor analysis to examine if a single-factor-model including waist circumference, triglycerides/HDL-c, insulin and mean arterial pressure underlies metabolic syndrome from the childhood to adolescence in a 6-years follow-up study in 174 Swedish and 460 Estonian children aged 9 years at baseline. Indeed, we analyze the tracking of a previously validated MS index over this 6-years period. Results: The estimates of goodness-of-fit for the single-factor-model underlying MS were acceptable both in children and adolescents. The construct stability of a new model including the differences from baseline to the end of the follow-up in the components of the proposed model displayed good fit indexes for the change, supporting the hypothesis of a single factor underlying MS component trends. Conclusions: A single-factor-model underlying MS is stable across the puberty in both Estonian and Swedish young people. The MS index tracks acceptably from childhood to adolescence.

¿Reflejan los índices de riesgo país las variables relevantes en el desencadenamiento de las crisis externas? Un análisis sobre el periodo 1994-2001

[ES] El objetivo de este trabajo es establecer en qué medida los índices de riesgo país más utilizados por la comunidad económica y financiera internacional, en concreto, el índice de Euromoney y el ICRG, recogen las variables relevantes en el desencadenamiento de las crisis monetarias y financieras externas, como un aspecto básico en la evaluación de su capacidad para medir adecuadamente el riesgo de los diferentes países.

Evaluación de la actividad investigadora: indicadores de calidad. Utilización de bases de datos en estudios bibliométricos.

[ES]La utilización de indicadores bibliométricos como los índices de citas y el factor de impacto se han convertido en herramientas imprescindibles tanto para la evaluación de la actividad investigadora como para la medición de la actividad económica y social de un país. El artículo analiza los indicadores para la evaluación de la calidad en la actividad investigadora y profundiza en la utilización de las bases de datos como herramienta de estudios bibliométricos.

A comprehensive method for the elastic calculation of the two-point wheel-rail contact

This work shows the method developed to solve the wheel-rail contact problem via a look-up table with a three-dimensional elastic model. This method enables introduction of the two contact point effect on vehicle movement using three-dimensional analysis of surfaces including the influence of the angle of attack. This work presents several dynamic simulations and studies the impact that the introduction of the two contact points on three dimensions has on wear indexes and derailment risk against traditional bidimensional analysis. Furthermore, it studies advantages and disadvantages of using a look-up table against an on-line resolution of the problem.

Approximate knowledge of rationality and correlated equilibria

We extend Aumann's [3] theorem deriving correlated equilibria as a consequence of common priors and common knowledge of rationality by explicitly allowing for non-rational behavior. We replace the assumption of common knowledge of rationality with a substantially weaker notion, joint p-belief of rationality, where agents believe the other agents are rational with probabilities p = (pi)i2I or more. We show that behavior in this case constitutes a constrained correlated equilibrium of a doubled game satisfying certain p-belief constraints and characterize the topological structure of the resulting set of p-rational outcomes. We establish continuity in the parameters p and show that, for p su ciently close to one, the p-rational outcomes are close to the correlated equilibria and, with high probability, supported on strategies that survive the iterated elimination of strictly dominated strategies. Finally, we extend Aumann and Dreze's [4] theorem on rational expectations of interim types to the broader p-rational belief systems, and also discuss the case of non-common priors.

Communities in complex networks

The study of complex networks has attracted the attention of the scientific community for many obvious reasons. A vast number of systems, from the brain to ecosystems, power grid, and the Internet, can be represented as large complex networks, i.e, assemblies of many interacting components with nontrivial topological properties. The link between these components can describe a global behaviour such as the Internet traffic, electricity supply service, market trend, etc. One of the most relevant topological feature of graphs representing these complex systems is community structure which aims to identify the modules and, possibly, their hierarchical organization, by only using the information encoded in the graph topology. Deciphering network community structure is not only important in order to characterize the graph topologically, but gives some information both on the formation of the network and on its functionality.

The Linear Ordering Problem Revisited

The Linear Ordering Problem is a popular combinatorial optimisation problem which has been extensively addressed in the literature. However, in spite of its popularity, little is known about the characteristics of this problem. This paper studies a procedure to extract static information from an instance of the problem, and proposes a method to incorporate the obtained knowledge in order to improve the performance of local search-based algorithms. The procedure introduced identifies the positions where the indexes cannot generate local optima for the insert neighbourhood, and thus global optima solutions. This information is then used to propose a restricted insert neighbourhood that discards the insert operations which move indexes to positions where optimal solutions are not generated. In order to measure the efficiency of the proposed restricted insert neighbourhood system, two state-of-the-art algorithms for the LOP that include local search procedures have been modified. Conducted experiments confirm that the restricted versions of the algorithms outperform the classical designs systematically. The statistical test included in the experimentation reports significant differences in all the cases, which validates the efficiency of our proposal.

Analysis of Spanish text-thesaurus as a complex network

[EN]Based on the theoretical tools of Complex Networks, this work provides a basic descriptive study of a synonyms dictionary, the Spanish Open Thesaurus represented as a graph. We study the main structural measures of the network compared with those of a random graph. Numerical results show that Open-Thesaurus is a graph whose topological properties approximate a scale-free network, but seems not to present the small-world property because of its sparse structure. We also found that the words of highest betweenness centrality are terms that suggest the vocabulary of psychoanalysis: placer (pleasure), ayudante (in the sense of assistant or worker), and regular (to regulate).

Advances towards behaviour-based indoor robotic exploration

215 p.

Valoración de la composición corporal y de la percepción de la imagen en un grupo de mujeres universitarias del País Vasco

Este trabajo se encuentra bajo la licencia Creative Commons Attribution 3.0.