8,581 research outputs found

    The twilight zone in the parametric evolution of eigenstates: beyond perturbation theory and semiclassics

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    Considering a quantized chaotic system, we analyze the evolution of its eigenstates as a result of varying a control parameter. As the induced perturbation becomes larger, there is a crossover from a perturbative to a non-perturbative regime, which is reflected in the structural changes of the local density of states. For the first time the {\em full} scenario is explored for a physical system: an Aharonov-Bohm cylindrical billiard. As we vary the magnetic flux, we discover an intermediate twilight regime where perturbative and semiclassical features co-exist. This is in contrast with the {\em simple} crossover from a Lorentzian to a semicircle line-shape which is found in random-matrix models.Comment: 4 pages, 4 figures, improved versio

    On the lack of stellar bars in Coma dwarf galaxies

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    We present a study of the bar fraction in the Coma cluster galaxies based on a sample of ~190 galaxies selected from the SDSS-DR6 and observed with the Hubble Space Telescope (HST) Advanced Camera for Survey (ACS). The unprecedented resolution of the HST-ACS images allows us to explore the presence of bars, detected by visual classification, throughout a luminosity range of 9 mag (-23 < M_r < -14), permitting us to study the poor known region of dwarf galaxies. We find that bars are hosted by galaxies in a tight range of both luminosities (-22 < M_r < -17) and masses (10^9 < M*/Msun < 10^11). In addition, we find that the bar fraction does not vary significantly when going from the center to the cluster outskirts, implying that cluster environment plays a second-order role in bar formation/evolution. The shape of the bar fraction distribution with respect to both luminosity and mass is well matched by the luminosity distribution of disk galaxies in Coma, indicating that bars are good tracers of cold stellar disks.Comment: 2 pages, 1 figure, to appear in the proceedings of the conference "A Universe of Dwarf Galaxies" (Lyon, June 14-18, 2010

    Sport education model versus traditional model: Effects on motivation and sportsmanship

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    El objetivo de este trabajo fue comparar los efectos que provocan los modelos de enseñanza Tradicional y de Educación Deportiva en la motivación y deportividad del alumnado de educación física, incluyendo también un tercer nivel de tratamiento, variante del modelo de Educación Deportiva, en el que se empleó material autoconstruido. Se realizó un diseño cuasi-experimental con tres niveles de tratamiento y medidas pretest y postest de cuatro variables dependientes: metas de logro, metas de amistad, necesidades psicológicas básicas y la deportividad durante la enseñanza del ultimate. Accedieron a participar un total de 295 estudiantes de secundaria y bachillerato cuyas edades oscilaban entre los 12-17 años. Los resultados indicaron mejoras significativas en las metas de evitación del rendimiento, metas de amistad, necesidades psicológicas básicas y subescalas de deportividad en ambos grupos de Educación DeportivaThe goal of the present project was to compare the effects of three different instructional models: (Traditional, Sport Education and Sport Education with Self-Made Materials) on physical education students' motivation and sportsmanship. A quasi-experimental design with three levels of treatment was used. Pretest and posttest scores on achievement goals, friendship, psychological needs and sportsmanship were obtained after the application of a learning unit of ultimate in a school in the northern part of Spain. A total of 295 secondary school students, ages 12-17, agreed to participate. Results showed significant increases in performance-avoidance goals, friendship goals, basic psychological needs and sportsmanship in both Sport Education groups. Sport Education seems to offer more advantages than the traditional teaching method to develop adolescents achievement and social goals, as well as sportsmanship, in physical educatio

    Integrating basic competences into physical education (Pe) in Primary Education

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    El objeto de este estudio fue evaluar la percepción de los maestros de Educación Física (EF) del Principado de Asturias sobre el proceso de incorporación de las competencias básicas (CCBB) en el currículo del área. Un total de 151 maestros de EF (46,6% de la población) contestaron a un cuestionario ad hoc compuesto por 12 ítems mediante una escala Likert de 6 puntos. Los resultados mostraron una plena incorporación de las CCBB a las programaciones, sin embargo, el nivel de desarrollo en la práctica resulta ser más bajo. Ser mujer, joven y contar con una elevada formación específica emergieron como factores diferenciales del trabajo competencial. Las competencias de carácter transversal fueron valoradas de mayor relevancia que las relacionadas con determinadas áreas curriculares. Se discute la profundidad del cambio emprendido por los docentes y el supuestamente requerido. Finalmente, se abordan sus implicaciones de cara al tipo de formación específicaThe purpose of this study was to assess Primary Education Physical Education (PE) teachers’ perspectives of the process of incorporating the Basic Competences (BBCC) into the curriculum of the Principality of Asturias. A total of 151 PE teachers (46.6% of the whole population) answered an ad hoc questionnaire of 12 items using a 6-point Likert scale. The results showed a full incorporation of the BBCC in the PE program. However, the degree of development in practice turned out to be lower. Being female, young, and having a high-level and specific training emerged as differentiating factors. Cross-cutting skills were valued more than those related to the specific curricular areas. The depth of change undertaken by the teachers compared to the required changed are discussed. Finally, implications to address specific training are also introduce

    Efectos de dos formatos instructivos, Educación Deportiva e Instrucción Directa, en la respuesta psicológica de estudiantes de secundaria

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    The goal of this study was to examine the effects of two instructional approaches, Sport Education and Direct Instruction, in a large sample of Spanish secondary education students’ psychological response. 217 (113 males, 104 females) students (12-17 years) from one urban, coeducational high school (grades 8-11th) agreed to participate. On each grade, all subjects were randomly distributed in two study groups: the experimental group experienced Sport Education, while the comparison group experienced Direct Instruction. Several subscales extracted from different questionnaires (PLOC, BPNES, IMI, SGS-PE, PMCSQ-2) were used to measure the effects of the intervention program. All data was analyzed using the SPSS 19.0 statistical program. Results showed that the Sport Education group significantly improved intrinsic motivation, autonomy, competence, interest, boredom, social responsibility, social relationship and cooperative learning. The Direct Instruction group showed significant gains only in autonomy, social responsibility and cooperative learning. Sport Education can significantly promote adaptive psychological responses in adolescents.El objetivo de este estudio fue examinar los efectos de dos formatos instructivos, Educación Deportiva e Instrucción Directa, en la respuesta psicológica de un grupo de estudiantes de secundaria. 217 (113 varones, 104 mujeres) estudiantes (12-17 años) de un colegio urbano (de 1º a 4º ESO) accedieron a participar. En cada nivel, todos los sujetos fueron distribuidos aleatoriamente en dos grupos de estudio: el grupo experimental experimentó Educación Deportiva y el grupo comparativo experimentó Instrucción Directa. Diferentes sub-escalas extraídas de varios cuestionarios (PLOC, BPNES, IMI, SGS-PE, PMCSQ-2) fueron usadas para medir los efectos del programa de intervención. Los datos fueron analizados utilizando el programa estadístico SPSS 19.0. Los resultados mostraron que el grupo de Educación Deportiva mejoró de manera significativa la motivación intrínseca, la autonomía, la competencia, el interés, el aburrimiento, la responsabilidad social, las relaciones sociales y el aprendizaje cooperativo. El grupo de Instrucción Directa mostró mejoras significativas solo en autonomía, responsabilidad social y aprendizaje cooperativo. La Educación Deportiva puede promover respuestas psicológicas adaptativas en adolescentes

    The origin of bulges and discs in the CALIFA survey – I. Morphological evolution

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    JMA acknowledge support from the Spanish Ministerio de Economia y Competitividad (MINECO) by the grant AYA2017-83204-P and the Programa Operativo FEDER Andalucia 2014-2020 in collaboration with the Andalucian Office for Economy and Knowledge. AdLC acknowledges financial support from the Spanish Ministry of Economy and Competitiveness (MINECO) under grants AYA201677237-C3-1-P and RTI2018-096188-B-I00, the latter is partly funded by the European Regional Development Fund (ERDF). SFS thanks the projects ConaCyt CB-285080, FC-2016-01-1916, and PAPIIT IN100519. This paper is based on data from the Calar Alto Legacy Integral Field Area Survey, CALIFA, funded by the Spanish Ministry of Science under grant ICTS-2009-10, and the Centro Astronomico Hispano-Aleman. This paper is based on observations collected at the Centro Astronomico Hispano Aleman (CAHA) at Calar Alto, operated jointly by the Max-Planck Institut fur Astronomie and the Instituto de Astrofisica de Andalucia.This series of papers aims at understanding the formation and evolution of non-barred disc galaxies. We use the new spectro-photometric decomposition code, C2D, to separate the spectral information of bulges and discs of a statistically representative sample of galaxies from the CALIFA survey. Then, we study their stellar population properties analysing the structure-independent datacubes with the PIPE3D algorithm. We find a correlation between the bulge-to-total (B/T) luminosity (and mass) ratio and galaxy stellar mass. The B/T mass ratio has only a mild evolution with redshift, but the bulge-to-disc (B/D) mass ratio shows a clear increase of the disc component since redshift z 10.5). The relation holds for bulges but not for discs when using their individual stellar masses. We find a negligible evolution of the mass-size relation for both the most massive (log(M-star,M-b,M-d/M-circle dot) > 10) bulges and discs. For lower masses, discs show a larger variation than bulges. We also find a correlation between the Sersic index of bulges and both galaxy and bulge stellar mass, which does not hold for the disc mass. Our results support an inside-out formation of nearby non-barred galaxies, and they suggest that (i) bulges formed early-on and (ii) they have not evolved much through cosmic time. However, we find that the early properties of bulges drive the future evolution of the galaxy as a whole, and particularly the properties of the discs that eventually form around them.Spanish Government AYA2017-83204-PPrograma Operativo FEDER Andalucia 2014-2020Andalucian Office for Economy and KnowledgeEuropean CommissionConsejo Nacional de Ciencia y Tecnologia (CONACyT) CB-285080Spanish Government ICTS-2009-10Centro Astronomico Hispano-AlemanPrograma de Apoyo a Proyectos de Investigacion e Innovacion Tecnologica (PAPIIT) IN100519Spanish Government AYA201677237-C3-1-P RTI2018-096188-B-I00 FC-2016-01-191

    An efficient, parametric fixpoint algorithm for analysis of java bytecode

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    Abstract interpretation has been widely used for the analysis of object-oriented languages and, in particular, Java source and bytecode. However, while most existing work deals with the problem of flnding expressive abstract domains that track accurately the characteristics of a particular concrete property, the underlying flxpoint algorithms have received comparatively less attention. In fact, many existing (abstract interpretation based—) flxpoint algorithms rely on relatively inefHcient techniques for solving inter-procedural caligraphs or are speciflc and tied to particular analyses. We also argüe that the design of an efficient fixpoint algorithm is pivotal to supporting the analysis of large programs. In this paper we introduce a novel algorithm for analysis of Java bytecode which includes a number of optimizations in order to reduce the number of iterations. The algorithm is parametric -in the sense that it is independent of the abstract domain used and it can be applied to different domains as "plug-ins"-, multivariant, and flow-sensitive. Also, is based on a program transformation, prior to the analysis, that results in a highly uniform representation of all the features in the language and therefore simplifies analysis. Detailed descriptions of decompilation solutions are given and discussed with an example. We also provide some performance data from a preliminary implementation of the analysis
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