How good are MatLab, Octave and Scilab for Computational Modelling?

In this article we test the accuracy of three platforms used in computational modelling: MatLab, Octave and Scilab, running on i386 architecture and three operating systems (Windows, Ubuntu and Mac OS). We submitted them to numerical tests using standard data sets and using the functions provided by each platform. A Monte Carlo study was conducted in some of the datasets in order to verify the stability of the results with respect to small departures from the original input. We propose a set of operations which include the computation of matrix determinants and eigenvalues, whose results are known. We also used data provided by NIST (National Institute of Standards and Technology), a protocol which includes the computation of basic univariate statistics (mean, standard deviation and first-lag correlation), linear regression and extremes of probability distributions. The assessment was made comparing the results computed by the platforms with certified values, that is, known results, computing the number of correct significant digits.Comment: Accepted for publication in the Computational and Applied Mathematics journa

El triángulo mágico : escuela, familia y comunidad en una intervención con jóvenes de contextos sociales desfavorecidos

En este artículo se presenta un estudio de casos llevado a cabo en la zona serrana de la región del Algarbe, Portugal. Se intenta comprender algunos aspectos del trabajo educativo con jóvenes de un medio social desfavorecido. Se plantea que los patrones de cambio cultural que han emergido pueden ser parcialmente explicados por un trabajo coordinado entre una diversidad de agentes educativos, que han buscado nuevas formas de diálogo. De esta forma, las relaciones entre familia, escuela y comunidad parecen fundamentales para producir cambios positivos en el trabajo educativo.__________________________________ In this paper we present a case studies research done in the mountainous area of the region of Algarve, Portugal. In it we try to understand some dimensions of the educational work concerning children of a clearly deprived social context. We sustain that the patterns of cultural change which have emerged can be partially explained by the coordinated work between a diversity of educational agents, who have searched new ways to dialogue. That being, the relationships between family, school and community seem fundamental to produce positive changes in educational work

Museos, desarrollo y cambio : la reacción de los espacios banales

Los museos son territorios simbólicos privilegiados de la contemporaneidad. A lo mejor puede ser una afirmación precipitada o apenas otra utopía museológica. Pero lo que es cierto es que los museos cambiaron o están en movimiento y no se parecen más con aquellos que Fillippo Marinetti quería destruir (Manifestó Futurista, 1909) o con aquellos que Paúl Valéry decía en no morirse de amores (O problema dos museus, 1923), para apenas nombrar dos de los más conocidos detractores. Entre los cambios más importantes verificados en los últimos años está el aparecimiento de las iniciativas espontáneas de la creación de nuevos museos, nacidos a partir de la articulación de los movimientos populares organizados, que no eran más únicamente conducidos por los poderes públicos. Una explicación para tal fenómeno es que los museos pasaron a ser vistos y reivindicados como un derecho esencial hasta el día de hoy, en su gran mayoría, negado como un espacio contemporáneo de participación y de reacción. Sin embargo, hasta qué punto podemos relacionar los museos, el desarrollo y los cambios sociales.Universidad Tecnológica de El Salvado

Vocabulary in foreign-language learning explorations of a neglected area

Dissertação(mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e ExpressãoExploração de questões preliminares com vistas a uma teoria da aquisição de vocabulário em língua estrangeira - LE e uma terminologia correlata. Investiga-se a produção local (Pós-Graduação em Inglês/UFSC) em áreas afins destacando-se o enfocado e o ignorado. Observações da literatura internacional permitem enfatizar a importância da proficiência lexical em vários aspectos do desempenho comunicativo e línguo-aquisicional de aprendizes de LE. Contraditoriamente, a literatura também aponta um certo descaso pelo assunto, relacionado a disputas lingüísticas teóricas sobre as relações entre léxico e gramática. Em descaso mais gritante está, em Lingüística Aplicada, o enfoque específico do conhecimento lexical e do processo de aquisição de vocabulário em LE. Um esquema das áreas de interesse ligadas a este objeto de descaso descortina um vasto 'campo' de assuntos interconexos e atividades correlatas. Deste campo, num segundo passo de aproximação, analisam-se as dimensões lingüísticas e psicológicas da proficiência lexical. Por fim, apontam-se ulteriores linhas de continuidade lógica desta investigação que é feita a partir do escrutínio de cerca de 150 trabalhos listados na bibliografia

Treatment of the Prominent Mandibular Angle by Using a Custom Made Surgical Splint

In this case report, we would like to present an alternative surgical technique for the treatment of the bilateral prominent mandibular angles by using a custom-made resin splint (template). The prefabricated template provided a precise outline for the osteotomy, which alleviated the uncertainty of the osseous cut. Furthermore, masseter muscle myomectomy was not necessary in this case which decreased morbidity, and procedure and recovery time, while assuring a more symmetric outcome

Searching for Orbits with Minimum Fuel Consumption for Station-Keeping Maneuvers: An Application to Lunisolar Perturbations

The present paper has the goal of developing a new criterion to search for orbits that minimize the fuel consumption for station-keeping maneuvers. This approach is based on the integral over the time of the perturbing forces. This integral measures the total variation of velocity caused by the perturbations in the spacecraft, which corresponds to the equivalent variation of velocity that an engine should deliver to the spacecraft to compensate the perturbations and to keep its orbit Keplerian all the time. This integral is a characteristic of the orbit and the set of perturbations considered and does not depend on the type of engine used. In this sense, this integral can be seen as a criterion to select the orbit of the spacecraft. When this value becomes larger, more consumption of fuel is required for the station keeping, and, in this sense, less interesting is the orbit. This concept can be applied to any perturbation. In the present research, as an example, the perturbation caused by a third body is considered. Then, numerical simulations considering the effects of the Sun and the Moon in a satellite around the Earth are shown to exemplify the method

Parametric Optimization of Low Thrust Orbital Maneuvers

The goal of the present paper is to make a numerical analysis of parametric optimization of low thrust orbital maneuver. An orbital maneuver occurs when it is necessary to modify the orbit a space vehicle to change its function or to correct effects of perturbations. A parametric optimization is made when the thrust is not free to point to any direction, but has to follow some prescribed law, like a linear or quadratic relation with time