Quantum wires in one dimension: disorder, electronic transport and dissipation

[EN]The dreamt idea of being able to make and control systems at the atomic scale has fascinated scientists since the middle of the past century. Nowadays, the wish of being able to create a miniaturization of electronic devices composed of novel techniques, to alter the microscopic nature of matter, has made possible the manufacture of semiconductor devices, to get to choose what the properties of it are. This technology is now a part of our Everyday Life, appearing in different systems ranging from semiconductor lasers to memory chips and microprocessors of computers, cellular phones and other digital appliances. Semiconductor heterostructures can be designed to change the dimensionality of the confinement of the carriers [95] (two-dimensional electron gas, quantum wires (1-D), quantum dots (0-D)) and this quality has been used to observe different phys- ical phenomena such as the Quantum Hall Effect or the electronic localization in disordered potentials

Global properties of the spectrum of the Haldane-Shastry spin chain

We derive an exact expression for the partition function of the su(m) Haldane-Shastry spin chain, which we use to study the density of levels and the distribution of the spacing between consecutive levels. Our computations show that when the number of sites N is large enough the level density is Gaussian to a very high degree of approximation. More surprisingly, we also find that the nearest-neighbor spacing distribution is not Poissonian, so that this model departs from the typical behavior for an integrable system. We show that the cumulative spacing distribution of the model can be well approximated by a simple functional law involving only three parameters.Comment: RevTeX 4, 7 pages, 4 figures. To appear in Phys. Rev.

Improving the surface finish of concave and convex surfaces using a ball burnishing process

The ball burnishing process is done to improve the surface finish of workpieces that have been previously machined. In this article we present the results of tests performed with this process that was applied to workpieces with a convex or concave surface of two different materials: aluminum A92017 and steel G10380. An experiment to do the tests was designed. The results of measurements of surface roughness are presented in this paper as well. These results are compared to those measured in the workpieces before being burnished. After that conclusions are drawn about the improvement of surface roughness applied to the workpieces through the ball burnishing process. The main innovation of this paper is that we work with concave and convex geometries. We also obtain a table of recomended parameter values for the process

Evaluating a human-robot interface for exploration missions

The research reported in this paper concerns the design, implementation, and experimental evaluation of a Human-Robot Interface for stationary remote operators, implemented for a PC computer. The GUI design and functionality is described. An Autonomy Management Model has been implemented and explained. We have conducted user evaluation, making two set of experiments, that will be described and the resulting data analyzed. The conclusions give an insight on the most important usability concerns, regarding the operator situational awareness. The scalability of the interface is also experimentally studied

Las chimeneas bajoextremeñas

Este artículo trata de la importancia de la cocina dentro de la casa extremeña, lugar de estancia y relación doméstica y, dentro de ella la chimenea, como el elemento más destacado de la cocina. El artículo trata de las clases de chimeneas , estructura, dimensiones, etc.This article deals with the importance of the kitchen within the house of Extremadura, the place of stay and domestic relationship and, within it, the chimney, as the most outstanding element of the kitchen. The article deals with the types of fireplaces, structure, dimensions, etc

Las chimeneas bajoextremeñas

Este artículo trata de la importancia de la cocina dentro de la casa extremeña, lugar de estancia y relación doméstica y, dentro de ella la chimenea, como el elemento más destacado de la cocina. El artículo trata de las clases de chimeneas , estructura, dimensiones, etc.This article deals with the importance of the kitchen within the house of Extremadura, the place of stay and domestic relationship and, within it, the chimney, as the most outstanding element of the kitchen. The article deals with the types of fireplaces, structure, dimensions, etc

Plazas, iglesias y casas del Concejo. Características e influencia en la configuración de las poblaciones

Este artículo analiza la preocupación de los monarcas cristianos peninsulares, en época de la Reconquista, por consagrar como iglesia católica la mezquita musulmana anterior en las poblaciones que ocupaban, si ésta existía, o se estimaba adecuada para tal destino, o la construcción inmediata de un edificio nuevo, en otro caso, para tal fin. También su ubicaron parroquias, en los momentos iniciales de los nuevos núcleos, en viejas ermitas. De ordinario, el nuevo templo se colocaba bajo la advocación del santo o festividad correspondiente al día en que se realizaba la ocupación del enclave. Las iglesias parroquiales adquirieron un papel relevante, no sólo como centro espiritual de cada núcleo, sino también por su papel en el terreno de la organización administrativa, y por sus funciones como bastión defensivo, atalaya de vigilancia, centro de reunión del vecindario, etc. No menos destacada resulta su influencia como foco de atracción y aglutinación para el asentamiento de pobladores y punto de referencia para la organización morfológica y espacial del caserío.This paper analyzes the preoccupation of the peninsular Christian monarchs, at the time of the Reconquest, to consecrate as a catholic church the previous Muslim mosque in the populations that they occupied, if it existed, or it was considered suitable for such destination, or the immediate construction of a new building, in another case, for that purpose. They also located parishes, in the initial moments of the new towns, in old hermitages. Ordinarily, the new temple was placed under the invocation of the saint or festivity corresponding to the day on which the occupation of the enclave took place. The parish churches acquired a relevant role, not only as the spiritual center of each town, but also for their role in the field of administrative organization, and for their functions as defensive bastion, watchtower of vigilance, center of meeting of the neighborhood, etc. No less outstanding is its influence as a focus of attraction and agglutination for the settlement and point of reference for the morphological and spatial organization of the hamlet

Construcciones y elementos urbanísticos peculiares en las poblaciones bajoextremeñas hasta el siglo XIX. Silos, pozos de nieve, horcas, fuentes y otros

Construcciones y elementos urbanísticos en las poblaciones bajoextremeñas hasta el siglo XIX: Silos, Pozos de nieve, Horcas, Fuentes y otros.Constructions and urban elements in the populations of extremadura until the nineteenth century: Silos, Snow Wells, Gallows, Fountains and other