A GPU-based Evolution Strategy for Optic Disk Detection in Retinal Images

La ejecución paralela de aplicaciones usando unidades de procesamiento gráfico (gpu) ha ganado gran interés en la comunidad académica en los años recientes. La computación paralela puede ser aplicada a las estrategias evolutivas para procesar individuos dentro de una población, sin embargo, las estrategias evolutivas se caracterizan por un significativo consumo de recursos computacionales al resolver problemas de gran tamaño o aquellos que se modelan mediante funciones de aptitud complejas. Este artículo describe la implementación de una estrategia evolutiva para la detección del disco óptico en imágenes de retina usando Compute Unified Device Architecture (cuda). Los resultados experimentales muestran que el tiempo de ejecución para la detección del disco óptico logra una aceleración de 5 a 7 veces, comparado con la ejecución secuencial en una cpu convencional.Parallel processing using graphic processing units (GPUs) has attracted much research interest in recent years. Parallel computation can be applied to evolution strategy (ES) for processing individuals in a population, but evolutionary strategies are time consuming to solve large computational problems or complex fitness functions. In this paper we describe the implementation of an improved ES for optic disk detection in retinal images using the Compute Unified Device Architecture (CUDA) environment. In the experimental results we show that the computational time for optic disk detection task has a speedup factor of 5x and 7x compared to an implementation on a mainstream CPU

A Dynamic Analysis of Household Decision-Making in Urban Colombia, 1976-1998: Changes in Household Structure, Human Capital and its Returns, and Female Labor Force Participation

The objective of this paper is to examine the changes and dynamics of household structure, human capital and the returns to education, labor earnings, women’s labor force participation and investment in human capital. The approach used in the analysis is the so-called "cohort technique," which consists of following across time men and women born in the same year or year spell. The main sources of information for this work are the quarterly Household Surveys beginning in 1976. With such information a database of more than 6 million observations (workers, parents, children, etc. ) was constructed. The research results show that the number of children of the younger parents has drastically decreased. This process has been accompanied by a significant increase in women’s labor force participation and higher women’s school attainment. The study also points out that the school attainment of the younger generation of women is higher than men’s and that the income gap between men and women of the new generation, after controlling for education, is lower than the gap in older generations. Finally, the study indicates that human capital accumulation has been very unequal for different income groups. The children of low educated parents achieve low levels of education both in old and new generations. Thus, escaping from the poverty trap is as difficult today as in the past, as education opportunities are concentrated in the middle and high-income groups.

The educational effects of 19th century disentailment of catholic church land in Colombia.

The aim of this paper is to analyze the effects of land concentration prompted by the distribution of disentailed Church land during the second half of the 19th century on the accumulation of human capital, in early 20th century Colombia1. Utilizing existing primary sources on the process of land disentailment and the 1912 National Census, descriptive statistics and econometric evidence show a significant and negative relationship between the amount of disentailed land during the 1870s at municipal level with literacy and school enrollment rates of males in 1912.Disentailment policy, land concentration, institutions, human capital, Colombian history

Approximation of tensor fields on surfaces of arbitrary topology based on local Monge parametrizations

We introduce a new method, the Local Monge Parametrizations (LMP) method, to approximate tensor fields on general surfaces given by a collection of local parametrizations, e.g.~as in finite element or NURBS surface representations. Our goal is to use this method to solve numerically tensor-valued partial differential equations (PDE) on surfaces. Previous methods use scalar potentials to numerically describe vector fields on surfaces, at the expense of requiring higher-order derivatives of the approximated fields and limited to simply connected surfaces, or represent tangential tensor fields as tensor fields in 3D subjected to constraints, thus increasing the essential number of degrees of freedom. In contrast, the LMP method uses an optimal number of degrees of freedom to represent a tensor, is general with regards to the topology of the surface, and does not increase the order of the PDEs governing the tensor fields. The main idea is to construct maps between the element parametrizations and a local Monge parametrization around each node. We test the LMP method by approximating in a least-squares sense different vector and tensor fields on simply connected and genus-1 surfaces. Furthermore, we apply the LMP method to two physical models on surfaces, involving a tension-driven flow (vector-valued PDE) and nematic ordering (tensor-valued PDE). The LMP method thus solves the long-standing problem of the interpolation of tensors on general surfaces with an optimal number of degrees of freedom.Comment: 16 pages, 6 figure

La interculturalidad en la asignatura de inglés de la E.S.O. bilingüe en Sevilla, España

La enseñanza de un idioma no puede separarse de la enseñanza de su(s) cultura(s) debido a que, como apuntan Grève y Van Passel (1971: 173), “la lengua representa en esencia uno de los principales aspectos de la cultura de una comunidad” y “el dominio de una lengua implica un conocimiento del uso social de la lengua y de su funcionamiento en las situaciones comunicativas diarias” (Gimeno Menéndez, 1997: 297). Sin embargo, los intentos de que el alumnado alcance conocimientos culturales apropiados para desenvolverse en interacciones con hablantes de otra lengua y cultura o, expresado con una terminología más reciente, de que adquiera una competencia interactiva intercultural para tal fin no están dando los frutos esperados debido al trato que se le da a la cultura, en términos de cantidad, calidad e importancia; el objetivo de este artículo es resumir un aspecto concreto de una investigación sobre la implementación y uso del auxiliar de conversación en el aula de inglés como lengua extranjera de centros bilingües español/inglés de Sevilla. Además de mostrar los resultados obtenidos en esta investigación en cuanto al trato de la cultura, se pretende contrastar estos resultados con los de estudios previos que resaltan carencias y ofrecen consejos y recomendaciones de mejora para, con esta comparación, validar, fortalecer e insistir en la puesta en marcha de estas y otras sugerencias.The teaching of a language cannot be separated from the teaching of its culture(s) due to the fact that, as Grève and Van Passel (1971: 173) point out, “the language essentially represents one of the main aspects of the culture of a community” and “the mastery of a language implies the knowledge of the language’s social usage and its functioning in everyday communicative situations” (Gimeno Menéndez, 1997: 297). However, the attempts to make the students reach appropriate cultural knowledge to function in interactions with speakers of another language and culture or, expressed through a more recent terminology, to acquire an intercultural interactive competence for the purpose are not showing the expected results because of the treatment culture receives in terms of quantity, quality and importance; the objective of this article is to summarize a specific aspect of a recent research related to the implementation and use of language assistants in the English as a foreign language classroom of Spanish/ English bilingual schools of Seville. Apart from showing the results of this research regarding the treatment of culture, these results will be compared with those of other previous studies that highlight shortcomings and offer advice and recommendations for improvement in order to validate, reinforce and insist on the implementation of these and other suggestions