1,818 research outputs found
Primera ediciĂłn del curso divulgadores de ciencia
Descubrir, analizar y comprobar cĂłmo el conocimiento cientĂfico ha sido transmitido, cĂłmo ha evolucionado y quiĂ©nes han sido sus protagonistas son los principales ejes del Curso Divulgadores de ciencia, organizado por el Observatorio de la ComunicaciĂłn CientĂfica (UPF) y patrocinado por el Ministerio de Ciencia y TecnologĂa, y cuya primera ediciĂłn se ha desarrollado durante los meses de noviembre y diciembre. El curso, con carácter semipresencial, ha recorrido la vida y obras de esos grandes cientĂficos que, además, han sido grandes sembradores de ideas e inquietudes cientĂficas
Variables predictivas de la satisfacciĂłn con la vida en estudiantes universitarios
[spa] Este trabajo presenta un estudio sobre el nivel de satisfacción general con la vida de una muestra de estudiantes universitarios. Se establece un modelo predictivo a partir de diversas variables independientes entre las que destacan: sentido vital, autoestima, nivel de estudios, valoraciones sobre el trabajo, la salud, las relaciones familiares y sociales, el estrés y su afrontamiento, redes de apoyo y competencias emocionales. Además de presentar los resultados en cada una de las variables evaluadas, se analizan las correlaciones más destacadas y se realiza un análisis de regresión paso a paso (stepwise) que identifica un conjunto de variables que explican el 64% de la satisfacción con la vida. La muestra está constituida por 609 estudiantes de grados y máster de diversas universidades catalanas y aragonesas. Es una muestra mayoritariamente femenina (81,1%) con edades oscilan entre los 18 y 67 años siendo la edad media de 31 años.[eng] This paper presents a study on the level of satisfaction with life in a sample of university students. A predictive model is established from diverse independent variables among which the following stand out: vital sense, self-esteem, level of studies, evaluations on job, health, family and social relationships, the stress and coping, social support and emotional competencies. In addition to presenting the results in each of the variables evaluated, correlations are analyzed and we used an analysis of stepwise regression that identifies a set of variables that explain the 64% satisfaction with life. The sample is composed of 609 students of degrees and master from diverse universities in Catalonia and Aragon. Sample is predominantly female (81.1%) aged between 18 and 67 years with an average age of 31 years old
Numerical analysis of rapid drawdown: applications in real cases
In this study, rapid drawdown scenarios were analyzed by means of numerical examples as well as modeling of real cases with in situ measurements. The aim of the study was to evaluate different approaches available for calculating pore water pressure distributions during and after a drawdown. To do that, a single slope subjected to a drawdown was first analyzed under different calculation alternatives, and numerical results were discussed. Simple methods, such as undrained analysis and pure flow analysis, implicitly assuming a rigid soil skeleton, lead to significant errors in pore water pressure distributions when compared with coupled flow-deformation analysis. A similar analysis was performed for the upstream slope of the Glen Shira Dam, Scotland, and numerical results were compared with field measurements during a controlled drawdown. Field records indicate that classical undrained calculations are conservative but unrealistic. Then, a recent case of a major landslide triggered by a rapid drawdown in a reservoir was interpreted. A key aspect of the case was the correct characterization of permeability of a representative soil profile. This was achieved by combining laboratory test results and a back analysis of pore water pressure time records during a period of reservoir water level fluctuations. The results highlight the difficulty of predicting whether the pore water pressure is overestimated or underestimated when using simplified approaches, and it is concluded that predicting the pore water pressure distribution in a slope after a rapid drawdown requires a coupled flow-deformation analysis in saturated and unsaturated porous media.Peer ReviewedPostprint (published version
Criteria for rapid sliding I.: a review of Vaiont case
Vaiont slide has been represented by a model of two interacting evolutive wedges. Mass conservation during the motion implies that the upper wedge transfers mass to the lower one through an internal shearing plane. The model respects available in situ observations. It was formulated in dynamics terms. Outcomes of the analysis are the determination of safety factors of the valley before dam impoundment, and the calculation of run-out distance once the motion starts. Rock strength degradation as motion develops has also been included. This degradation, even if it is intense, was unable to explain the very high estimated landslide velocities.Peer ReviewedPostprint (author's final draft
Slope stability in slightly fissured claystones and marls
The final publication is available at Springer via http://dx.doi.org/10.1007/s10346-014-0526-5The paper deals with the behavior of some characteristic soft rocks found in the Iberian Peninsula. In geological terms, they belong to Tertiary basins, the Keuper period and the Jurassic-Cretacic transition. The discussion is organized around the following aspects: (a) the intact material and its brittle behavior; (b) the weathering action of atmospheric events; (c) the persistent discontinuities and scale effects; and (d) the modification of strength after failure. In all cases, instability phenomena are addressed in connection with several case histories. Regarding material brittleness and the initial stress state, two cases of first time failures are discussed. Practical implications concerning the selection of operative strength will be given. Field observations of the relevance of weathering and, also, on the rate of weathering, are given for a Weald claystone. Field observations emphasize the importance of sharp transitions between weathered and intact (or slightly weathered) levels. A recent long-term laboratory investigation on the nature of degradation will be summarized. Macroscopic variables such as stiffness and tensile strength have been found to be uniquely predicted by a degradation law in terms of the accumulated plastic deformations. Persistent discontinuities and, in particular, sedimentation planes play a dominant role to explain slope failures not related to the shallow failures, usually associated with weathered profiles. The strength of discontinuities in a Weald formation was investigated by means of tests performed at two scales. Finally, the evolution in time of residual strength induced by chemical actions, associated with groundwater flow, is highlighted in connection with actual field data of unstable slopes.Peer ReviewedPostprint (author's final draft
Criteria for rapid sliding II.: thermo-hydro-mechanical and scale effects in Vaiont case
Thermally induced excess pore pressures have been included into a two-wedge evolutive model of Vaiont landslide. The problem requires the solution of a system of four coupled balance equations for the shear bands and the surrounding rock as well as the joint equation of motion of the entire slide. The model predicts the high velocities observed and is consistent with other data (slide geometry, residual strength, and conditions on the sliding surface). The interpretation of a sensitivity analysis suggests that there exists a threshold permeability band, in the range 10- 8 to 10- 10 m/s, which separates potentially fast motions from slow motions. This conclusion is maintained if the scale of the landslide is reduced.Peer ReviewedPostprint (author's final draft
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