Empirical likelihood confidence intervals for complex sampling designs

We define an empirical likelihood approach which gives consistent design-based confidence intervals which can be calculated without the need of variance estimates, design effects, resampling, joint inclusion probabilities and linearization, even when the point estimator is not linear. It can be used to construct confidence intervals for a large class of sampling designs and estimators which are solutions of estimating equations. It can be used for means, regressions coefficients, quantiles, totals or counts even when the population size is unknown. It can be used with large sampling fractions and naturally includes calibration constraints. It can be viewed as an extension of the empirical likelihood approach to complex survey data. This approach is computationally simpler than the pseudoempirical likelihood and the bootstrap approaches. The simulation study shows that the confidence interval proposed may give better coverages than the confidence intervals based on linearization, bootstrap and pseudoempirical likelihood. Our simulation study shows that, under complex sampling designs, standard confidence intervals based on normality may have poor coverages, because point estimators may not follow a normal sampling distribution and their variance estimators may be biased.<br/

Fluid-physics-module experiments

Some floating-liquid-zone experiments performed under reduced-gravity conditions are reviewed. Several types of instabilities are discussed, together with the relevant parameters controlling them. It is shown that the bounding values of these parameters could be increased, by orders of magnitude in several instances, by selecting appropriate liquids. Two of the many problems that a Fluid-Physics Module, devised to perform experiments on floating zones in a space laboratory, would involve are discussed: namely (i) procedures for disturbing the zoneunder controlled conditions, and (ii) visualisation of the inner flow pattern. Several topics connected with the nonisothermal nature and the phase-changes of floating zones are presented. In particular, a mode of propagation through the liquid zone for disturbances which could appear in the melting solid/liquid interface is suggested. Although most research on floating liquid zones is aimed at improving the crystal-growth process, some additional applications are suggested

Expediciones de ayer y hoy

Peer reviewe

Diffusion flames and supersonic combustion 2

Some problems related to the fluid dynamical and chemical phenomena appearing near the injector exit of an idealized supersonic combustion burner, are theoretically investigated. When hydrogen is injected into a coflowing supersonic stream of air,a wake-like configuration appears in most cases,improving the mixing process. It is only natural to suggest that whenever the ignition delay length, computed assuming isobaric mixing and reaction, is not much larger than the recirculation zone length, the wake will influence the ignition zone. In order to calculate the ignition delay length, the usual assumption is made that fuel and oxidizer mix without appreciable concentration change and heat release resulting from chemical reactions, although radicals, mainly atomic hydrogen, are produced. The chemical kinetics scheme is reduced to one overall chemical reaction; and the presence of radicals introduced in the mixing zone from outside is taken into account. A two-dimensional mixing zone has been considered. Although many different mechanisms will be responsible for the fortuitous or provoked production of these radicals either in real flight or in ground testing facilities, dissociation at the injector outer boundary layer is considered in this paper as the main radicals producing mechanism. As it is shown, the temperature of the injector outer wall and, to a less extent, pressure, injector length and the conditions outside of the boundary layer, control the amount of radicals introduced in the mixing layer, and hence the ignition delay length. Finally, it is shown that ignition delay lengths are, in most cases of interest, comparable to the near-wake length. The paper ends with a discussion of the main weaknesses of the work presented and with some suggestions for further work

La biblioteca de la Universidad de Salamanca : memoria anual y noticia histórica de la misma

Copia digital. Valladolid : Junta de Castilla y León. Consejería de Cultura y Turismo, 2009-201

Reflections on my experience as a learner of languages and on how that experience may have influenced my teaching style and practice

En este artículo pretendo hacer una reflexión personal desde mi infancia sobre mi propia adquisición y aprendizaje de idiomas tomando el castellano como punto de partida y siguiendo con el posterior estudio y adquisición de otras lenguas extranjeras. Esta introspección me llevará a analizar hasta qué punto las experiencias vividas, tanto positivas como negativas, han podido influir en los métodos y estilos de aprendizaje que imparto en mis clases al día de hoy.The following article is an introspection into my childhood and early youth memories in relation to language acquisition and learning of foreign languages. This analysis will help me determine to what extent these experiences, positive and negative ones, may have influenced my teaching methods and style to the present day

Esquema para un esbozo histórico del Proyectar

Destino es prefiguración de lo que ha de ocurrir. Seguir un inevitable camino hacia un fin consabido. Predeterminación. Proyecto, carácter, libertad, innovación, dignidad, es seguir la trayectoria del deseo, es derivar en el hacer, es entregarse al proceder. Destino apunta a tipo, a prefigurado. Proyecto apunta a alternativa, a ir contra, a rebelarse al destino... Innovar, para Alexander. Lanzar lo alternativo soñado como futuro (utopía, tendencia) o como bandera de futuro (manifiesto). Proyecto es inclinació