Rectangular Potentials in a Semi-Harmonic Background: Spectrum, Resonances and Dwell Time

We study the energy properties of a particle in one dimensional semi-harmonic rectangular wells and barriers. The integration of energies is obtained by solving a simple transcendental equation. Scattering states are shown to include cases in which the impinging particle is 'captured' by the semi-harmonic rectangular potentials. The 'time of capture' is connected with the dwell time of the scattered wave. Using the particle absorption method, it is shown that the dwell time $\tau^a_D$ coincides with the phase time $\tau_W$ of Eisenbud and Wigner, calculated as the energy derivative of the reflected wave phase shift. Analytical expressions are derived for the phase time $\tau_W$ of the semi-harmonic delta well and barrier potentials

CIXL2: A Crossover Operator for Evolutionary Algorithms Based on Population Features

In this paper we propose a crossover operator for evolutionary algorithms with real values that is based on the statistical theory of population distributions. The operator is based on the theoretical distribution of the values of the genes of the best individuals in the population. The proposed operator takes into account the localization and dispersion features of the best individuals of the population with the objective that these features would be inherited by the offspring. Our aim is the optimization of the balance between exploration and exploitation in the search process. In order to test the efficiency and robustness of this crossover, we have used a set of functions to be optimized with regard to different criteria, such as, multimodality, separability, regularity and epistasis. With this set of functions we can extract conclusions in function of the problem at hand. We analyze the results using ANOVA and multiple comparison statistical tests. As an example of how our crossover can be used to solve artificial intelligence problems, we have applied the proposed model to the problem of obtaining the weight of each network in a ensemble of neural networks. The results obtained are above the performance of standard methods

Optical Supersymmetry in the Time Domain

Originally emerged within the context of string and quantum field theory, and later fruitfully extrapolated to photonics, the algebraic transformations of quantum-mechanical supersymmetry were conceived in the space realm. Here, we introduce a paradigm shift, demonstrating that Maxwell's equations also possess an underlying supersymmetry in the time domain. As a result, we obtain a simple analytic relation between the scattering coefficients of a large variety of time-varying optical systems and uncover a wide new class of reflectionless, three dimensional, all-dielectric, isotropic, omnidirectional, polarization-independent, non-complex media. Temporal supersymmetry is also shown to arise in dispersive media supporting temporal bound states, which allows engineering their momentum spectra and dispersive properties. These unprecedented features define a promising design platform for free-space and integrated photonics, enabling the creation of a number of novel reconfigurable reflectionless devices, such as frequency-selective, polarization-independent and omnidirectional invisible materials, compact frequency-independent phase shifters, broadband isolators, and versatile pulse-shape transformers

Los cultos egipcios en Hispania: addenda a una publicación reciente

En el presente trabajo se añaden dos piezas no tenidas en cuenta en el recientemente publicado repertorio de documentos vinculados a los cultos egipcio-romanos presentes en la península Ibérica: una jarra cerámica de la producción TSH riojana con representaciones de Harpócrates y Anubis, y un entalle con un busto de Harpócrates encontrado en El Hito (Cuenca).In the present work two more pieces are added to the recently published document repertory related to the Egyptian-Roman cults present in the Iberian Peninsula: a ceramic jar of the TSH production from La Rioja with depictions of Harpocrates and Anubis, and an intaglio with a bust of Harpocrates found in El Hito (Cuenca)

Los amuletos de tipo egipcio de la Colección Pérez-Cabrero i Tur del Museo de Prehistoria de Valencia

La Colección Pérez-Cabrero i Tur, depositada en el Servicio de Investigación Prehistórica de Valencia, consta de un conjunto de materiales arqueológicos procedentes de la isla de Ibiza, entre los cuales se encuentran doce amuletos de tipo egipcio. El objetivo de nuestro trabajo es la publicación completa del repertorio, resolviendo las dudas planteadas en cuanto a la identificación de algunas piezas

The relevance of English in the tourist industry

In this project, English is analysed as an international language and vehicle of communication in the tourist industry, especially in hotel industry and means of transports: air transport, water-based transport and rail transportation. It is studied to what extent English is used by professional people in the sector and by inbound tourists, find out what is their level. Oral and written skills, departments and communication codes are analysed in order to verify the kind of English necessary to communicate in the service sector.Universidad de Sevilla. Grado en Turism

Imágenes para la memoria. Fotografías de las muestras de duelo por el 11-M

Actas del Primer Congreso Internacional sobre Imagen, Cultura y Tecnología celebrado del 3 al 5 de septiembre de 2008 en la Universidad Carlos III de Madri