Optimal light harvesting structures at optical and infrared frequencies

One-dimensional light harvesting structures with a realistic geometry nano-patterned on an opaque metallic film are optimized to render high transmission efficiencies at optical and infrared frequencies. Simple design rules are developed for the particular case of a slit-groove array with a given number of grooves that are symmetrically distributed with respect to a central slit. These rules take advantage of the hybridization of Fabry-Perot modes in the slit and surface modes of the corrugated metal surface. Same design rules apply for optical and infrared frequencies. The parameter space of the groove array is also examined with a conjugate gradient optimization algorithm that used as a seed the geometries optimized following physical intuition. Both uniform and nonuniform groove arrays are considered. The largest transmission enhancement, with respect to a uniform array, is obtained for a chirped groove profile. Such enhancement is a function of the wavelength. It decreases from 39% in the optical part of the spectrum to 15% at the long wavelength infrared.Comment: 13 pages, 5 figure

El agregado de Hordeum murinum (poaceae) en “Flora iberica”

Hordeum murinum aggregate in “Flora iberica”Palabras clave. Hordeum, Poaceae, corología, taxonomía, Hordeae.Key words. Hordeum, Poaceae, chorology, taxonomy, Hordeae

Contact Lagrangian systems subject to impulsive constraints

We describe geometrically contact Lagrangian systems under impulsive forces and constraints, as well as instantaneous nonholonomic constraints which are not uniform along the configuration space. In both situations, the vector field describing the dynamics of a contact Lagrangian system is determined by defining projectors to evaluate the constraints by using a Riemannian metric. In particular, we introduce the Herglotz equations for contact Lagrangian systems subject to instantaneous nonholonomic constraints. Moreover, we provide a Carnot-type theorem for contact Lagrangian systems subject to impulsive forces and constraints, which characterizes the changes of energy due to contact-type dissipation and impulsive forces. We illustrate the applicability of the method with practical examples, in particular, a rolling cylinder on a springily surface and a rolling sphere on a non-uniform surface, both with dissipation.Comment: 23 page

A mortalidade por tuberculose em Puerto de Santa María (1923-1926)

La principal causa de mortalidad en El Puerto de Santa María (Cádiz) durante 1923-1926 es la tuberculosis. El objetivo es analizar la mortalidad por Tuberculosis en dicha localidad durante 1923 a 1926, relacionándola con los principales determinantes epidemiológicos, contribuyendo a la interpretación de la realidad sanitaria de la época. Estudio descriptivo, longitudinal de la mortalidad por tuberculosis en El Puerto durante 1923 a 1926. Las fuentes fueron los libros de Actas de defunción del registro civil. Se realizó el análisis estadístico de las variables (causa de defunción, sexo, edad…), con el programa SPSS 15.0. El total de defunciones por tuberculosis fueron 217 (13,7%) y la Tasa de Mortalidad específica de 28,22 por diez mil habitantes. Atendiendo al sexo, el 54% (117) corresponden a hombres y el 46% (100) a mujeres. Las conclusiones son: 1. La Tuberculosis es la primera causa de mortalidad en El Puerto entre 1923-1926. 2. El patrón que sigue la mortalidad por tuberculosis en El Puerto es superponible al del resto de la provincia. 3. Es necesario una serie temporal más amplia para poder asignar la causa del descenso de las defunciones en 1926 a las mejoras de las condiciones higiénico-sanitarias derivadas de la actuación institucional.The main cause of mortality in El Puerto de Santa María (Cádiz) between 1923 and 1926 was tuberculosis. Our aim is to analyse the tuberculosis mortality rate in this town between 1923 and 1926 and to link it to the principal epidemiological determinants in order to describe the health and sanitary conditions in those years. Descriptive and longitudinal study of the tuberculosis mortality in El Puerto de Santa María between 1923 and 1926. Our information sources were the entries in the register of deaths. A statistical analysis of the variables was carried out (death cause, sex, age…), with the programme SPSS15.0. The total amount of deaths caused by tuberculosis was 217 (13,7%) and the specific mortality rate was 28,22 in 10,000 inhabitants. 54% (117) were males and 46% (100) females. We can conclude: 1. Tuberculosis was the first cause of death in El Puerto between 1923 and 1926. 2. The tuberculosis mortality standards are similar in the rest of the province of Cadiz. 3. It would be necessary to perform a deeper study to know whether the cause of the decrease in the mortality rate in 1926 was a consequence of an improvement in health and sanitary policies.A principal causa de mortalidade em Puerto de Santa María (Cádiz) entre os anos de 1923 e 1926 é a tuberculose. O objetivo é analisar a mortalidade por tuberculose nesta localidade durante o período de 1923 a 1926, relacionando-a com os principais determinantes epidemiológicos, contribuindo para a interpretação da realidade sanitária da época. Trata-se de um estudo descritivo, longitudinal, da mortalidade por tuberculose em Puerto de Santa María de 1923 a 1926. As fontes foram os registos de óbitos do Registo civil. Realizou-se uma análise estatística das variáveis (causa de morte, sexo, idade…), com o programa SPSS 15.0. O total de óbitos por tuberculose foi de 217 (13,7%) e a Taxa de Mortalidade específica de 28,22 por dez mil habitantes. Relativamente ao sexo, 54% (117) correspondem a homens e 46% (100) a mulheres. As conclusões são as seguintes: 1. A tuberculose é a primeira causa de mortalidade em Puerto de Santa María entre 1923-1926. 2. O padrão de tuberculose na localidade é superior ao do resto da província. 3. É necessária uma série temporal mais ampla para poder atribuir a causa da descida dos óbitos em 1926 à melhoria das condições higiénico-sanitárias derivadas da atuação institucional

Multilevel Multiphase Feedforward Space-Vector Modulation Technique

Multiphase converters have been applied to an increasing number of industrial applications in recent years. On the other hand, multilevel converters have become a mature technology mainly in medium- and high-power applications. One of the problems of multilevel converters is the dc voltage unbalance of the dc bus. Depending on the loading conditions and the number of levels of the converter, oscillations appear in the dc voltages of the dc link. This paper presents a feedforward modulation technique for multilevel multiphase converters that reduces the distortion under balanced or unbalanced dc conditions. The proposed modulation method can be applied to any multilevel-converter topology with any number of levels and phases. Experimental results are shown in order to validate the proposed feedforward modulation technique.Ministerio de Ciencia e Innovación DPI2009-07004Ministerio de Eduación y Ciencia TEC2007-6187

Matemáticas para la sociedad: una visión desde los libros de aritmética del siglo XVI

Dentro de las investigaciones en Historia de la Educación Matemática el análisis de libros antiguos utilizados para la enseñanza de las matemáticas supone una importante fuente de información. Esto se debe a que los textos antiguos ayudan a reconstruir los conceptos, a contextualizarlos y a conocer sus diversos acercamientos, a interrogarse sobre la validez de las formas de argumentar vigentes en otras épocas, y a buscar los fundamentos de las formas actuales. De la misma forma, aportan información sobre lo pedagógico: las formas de organizar y presentar el contenido, sus representaciones, las situaciones, problemas y ejercicios utilizados para explicar mejor los conceptos y métodos matemáticos (Gómez, 2001). En este sentido, el objetivo de este estudio es identificar el interés social que otorgan los autores de libros de aritmética del siglo XVI a las matemáticas, es decir, si los contenidos matemáticos presentes en las obras se pueden encontrar dentro de algún contexto cotidiano, científico, económico, militar, etc

Tail autotomy effects on the escape behavior of the lizard Gonatodes albogularis (Squamata: Sphaerodactylidae), from Córdoba, Colombia

Background: Caudal autotomy appears to be an adaptation strategy to reduce the risk of being preyed upon. In an encounter with a predator, the prey must reduce the risk of being preyed upon, and one of the strategies that has exerted a strong pressure on selection has been tail loss. In lizards, it has been demonstrated that tail loss reduces the probability of survival in the event of a second attack; therefore, they must resort to new escape strategies to reduce the risk of falling prey. In order to evaluate the effect of tail loss on the escape behavior of Gonatodes albogularis in natural conditions, we took samples from a forest interior population. We expected that individuals that had not lost their tails would allow the predator to get closer than those that had lost it. For each sample, we recorded the following: (1) escape behavior, measured through three distances (e.g., approach distance, escape distance, and final distance); (2) distance to shelter; and (3) length of tail. We included only males in the study since we did not record any females without a tail and far fewer with a regenerated tail. Results: We found that tail loss does have an effect on the escape behavior of G. albogularis. Males that have their tails intact allow the predator to come closer, and we found a negative correlation between the approach distance and the length of the tail. Conclusion: Our results support the escape behavior theory, in which G. albogularis males drop their tails when the risk of predation is much higher than the cost of fleeing.Facultad de Ciencias Naturales y Muse

Tail autotomy effects on the escape behavior of the lizard Gonatodes albogularis (Squamata: Sphaerodactylidae), from Córdoba, Colombia

Background: Caudal autotomy appears to be an adaptation strategy to reduce the risk of being preyed upon. In an encounter with a predator, the prey must reduce the risk of being preyed upon, and one of the strategies that has exerted a strong pressure on selection has been tail loss. In lizards, it has been demonstrated that tail loss reduces the probability of survival in the event of a second attack; therefore, they must resort to new escape strategies to reduce the risk of falling prey. In order to evaluate the effect of tail loss on the escape behavior of Gonatodes albogularis in natural conditions, we took samples from a forest interior population. We expected that individuals that had not lost their tails would allow the predator to get closer than those that had lost it. For each sample, we recorded the following: (1) escape behavior, measured through three distances (e.g., approach distance, escape distance, and final distance); (2) distance to shelter; and (3) length of tail. We included only males in the study since we did not record any females without a tail and far fewer with a regenerated tail. Results: We found that tail loss does have an effect on the escape behavior of G. albogularis. Males that have their tails intact allow the predator to come closer, and we found a negative correlation between the approach distance and the length of the tail. Conclusion: Our results support the escape behavior theory, in which G. albogularis males drop their tails when the risk of predation is much higher than the cost of fleeing.Facultad de Ciencias Naturales y Muse