ELECTRONIC STATES IN GRADED-GAP JUNCTIONS WITH BAND INVERSION

We theoretically study electronic states in graded-gap junctions of IV-VI compounds with band inversion. Using a two-band model within the ${\bf k}\cdot{\bf p}$ approximation and assuming that the gap and the gap centre present linear profiles, we demonstrate the existence of a set of localized states along the growth direction with a discrete energy spectrum. The envelope functions are found to be combination of harmonic oscillator eigenfunctions, and the corresponding energy levels are proportional to the square root of the quantum number. The level spacing can be directly controlled by varying the structure thickness.Comment: REVTEX 3.0, 7 pages, no figures, to appear in Phys. Lett.

Vortex dynamics in disordered Josephson junction arrays: from plastic flow to flux flow

We study the dynamics of Josephson junction arrays with positional disorder and driven by an external current. We consider weak magnetic fields, corresponding to a frustration $f=n+1/25$ with $n$ integer. We find that above the critical current $i_c$ there is a plastic flow of vortices, where most of the vortices are pinned and only a few vortices flow through channels. This dynamical regime is characterized by strong fluctuations of the total vorticity. The number of the flow channels grow with increasing bias current. At larger currents there is a dynamical regime characterized by the homogeneous motion of all the vortices, i.e. a flux flow regime. We find a dynamical phase transition between the plastic flow and the flux flow regimes when analyzing voltage-voltage correlation functions.Comment: 9 pages. 3 Figures available upon request. Presented in the Workshop on Josephson Junction Arrays, ICTP (August 1995). To appear in Physica B (1996

Exact Solutions of Two-Band Models of Graded-Gap Superlattices

We have theoretically investigated two-band models of graded-gap superlattices within the envelope-function approximation. Assuming that the gap varies linearly with spatial coordinate, we are able to find exact solutions of the corresponding Dirac-like equation describing the conduction- and valence-band envelope-functions. The dispersion relation inside allowed miniband of the superlattice may be expressed in terms of confluent hypergeometric functions in a closed form.Comment: 7 pages in REVTeX 3.0. 1 Figure on request to F. D-A ([email protected]). FM-UCM-3

Theory of anomalous collective diffusion in colloidal monolayers on a spherical interface

A planar colloidal monolayer exhibits anomalous collective diffusion due to the hydrodynamic interactions. We investigate how this behavior is affected by the curvature of the monolayer when it resides on the interface of a spherical droplet. It is found that the characteristic times of the dynamics still exhibit the same anomalous scaling as in the planar case. The spatial distribution, however, shows a difference due to the relevance of the radius of the droplet. Since for the droplet this is both a global magnitude, i.e., pertaining the spatial extent of the spherical surface, and a local one, i.e., the radius of curvature, the question remains open as to which of these two features actually dominates in the case of a generically curved interface.Comment: 7 pages, 2 figure

A Genetic Algorithm for solving the Discrete Ordered Median Problem with Induced Order

The Discrete Ordered Median Problem with Induced Ordered (DOMP+IO) is a multi-facility version of the classical discrete ordered median problem (DOMP), which has been widely studied. Several exact methods have been proposed to solve the DOMP, however these methods could only solve small-scale problems, which are far of real-life problems. In this work, a DOMP+IO with two kinds of facilities is considered and a heuristic method is proposed for its solving. The proposed procedure is based on a genetic algorithm and the preliminary results show the efficiency and capability to obtain good solutions for large-scale problems.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

A Proposal of a Synthetic Indicator to Measure Poverty Intensity, With an Application to EU-15 Countries

This paper deals with the proposal of a synthetic indicator to measure intensity of poverty. So, whereas incidence of poverty can be clearly measured using the headcount ratio indicator, according to Sen (1976) dimensions of poverty, the choice of a better intensity poverty measure is still an open question to resolve. Thus, in this paper, a new procedure to obtain a synthetic indicator from a set of well-performed poverty intensity indices as a start is proposed, using an adaptation of Principal Component Analysis (PCA). Conditions needed to make longitudinal comparisons possible are studied and properties of these synthetic indicators will also be analyzed, connected to TIP curves as well. As an illustration, this paper analyzes the evolution of poverty in the 15 countries of E.U., whose household income data are available through the information contained in the European Community Household Panel (ECPH). This analysis allows static and dynamic comparisons, related to the period from 1993 to 2000. Furthermore, the determination of groups of countries according to their characteristics in poverty will be accomplished.Economic Poverty, TIP’s poverty curves, Poverty in EU countries, PHOGUE.

Filogeografía: aplicaciones en taxonomía y conservación

La filogeografía se define como la disciplina que estudia los principios y procesos que gobiernan la distribución geográfica de los linajes genealógicos. Dos de las áreas de estudio donde se utilizan aproximaciones filogeográficas cada vez con mayor frecuencia son la taxonomía y la conservación. En esta revisión presentamos primero un resumen general sobre filogeografía y posteriormente discutimos cómo se han llevado al cabo estudios de taxonomía y conservación empleando aproximaciones filogeográficas, enfatizando sobre todo las limitaciones que deben considerarse. Incluimos ejemplos relevantes de estudios con animales que permitirán a los lectores conocer el sentido y alcance de dichas aplicaciones y diseñar adecuadamente estudios con estos objetivos. Palabras clave: ADN, Biogeografía, Estructura genética, Genealogía.Phylogeography is defined as the discipline that studies the principles and processes that determine the geographical distribution of genealogical lineages. Two of the study areas where phylogeographic approaches are used more and more frequently are taxonomy and conservation. In this review we first present a general description of phylogeography and then discuss how research in taxonomy and conservation has been addressed when using phylogeographic approaches, emphasising in particular the limitations that need to be considered. We include relevant examples of studies with animals in order to help readers acquire the sense and scope of such applications and select the appropriate study design to meet these objectives. Key words: DNA, Biogeography, Genetic structure, Genealogy.La filogeografía se define como la disciplina que estudia los principios y procesos que gobiernan la distribución geográfica de los linajes genealógicos. Dos de las áreas de estudio donde se utilizan aproximaciones filogeográficas cada vez con mayor frecuencia son la taxonomía y la conservación. En esta revisión presentamos primero un resumen general sobre filogeografía y posteriormente discutimos cómo se han llevado al cabo estudios de taxonomía y conservación empleando aproximaciones filogeográficas, enfatizando sobre todo las limitaciones que deben considerarse. Incluimos ejemplos relevantes de estudios con animales que permitirán a los lectores conocer el sentido y alcance de dichas aplicaciones y diseñar adecuadamente estudios con estos objetivos. Palabras clave: ADN, Biogeografía, Estructura genética, Genealogía

Los estudiantes de Huelva y la II República

Este trabajo pretende poner de relieve la activa participación de los estudiantes de Huelva en la vida docente del Instituto La Rábida y de la Escuela Normal, sus inquietudes por la cultura académica y de la clase obrera, así como la constante participación en los Congresos de la Unión Federal de Estudiantes Hispanos durante los primeros años del gobierno republicano. Recoge igualmente los escasos episodios conflictivos que se generaron en los centros de estudiantiles de la capital comparados con los que se estaban produciendo en las aulas universitarias españolas. Por último se constata el debilitamiento de la FUE y el creciente ascenso del SEU.________________________The aim of this study is to point out the participation of the students of Huelva in the educational life of the secondary school "La Rábida" and in the Teaching Training Centre. It also pays attention to their interest in the academic culture, the working class, and their role in the Conference of the Federal Union of Hispanic Students. Finally, this essay also deals with the conflicting situation at University which, though in a minimal way, affected the young members of the FUE in our province

Foreground detection enhancement using Pearson correlation filtering

Foreground detection algorithms are commonly employed as an initial module in video processing pipelines for automated surveillance. The resulting masks produced by these algorithms are usually postprocessed in order to improve their quality. In this work, a postprocessing filter based on the Pearson correlation among the pixels in a neighborhood of the pixel at hand is proposed. The flow of information among pixels is controlled by the correlation that exists among them. This way, the filtering performance is enhanced with respect to some state of the art proposals, as demonstrated with a selection of benchmark videos.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech