Sistema Regional de Información
en línea para Revistas Científicas de América Latina,
el Caribe, España y Portugal

This article aims to present the results of a systematic raised pedagogical experience in the application of the learning strategy called the didactic sequence (DS) to develop a thematic course unit in the FD-1027 Teaching Literacy course, which is part of the curriculum of the Primary Education School of the University of Costa Rica. The study’s purpose was to improve the learning processes on didactic principles regarding the stages of composition of texts in the school years. The innovation implemented was an action-research which follows the qualitative approach, due to the interest of describing, interpreting and understanding a problem to then reflect upon it and find its appropriate solutions. In this regard, three phases of work were established with the participation of 27 students. According to the results, it can be concluded that the strategy allowed to develop the thematic unity of the stages of composition of writing in a logical way; and also, that it provided students’ application of research skills in textual production, which evidently generates a greater empowerment of educational principles. It is important to note that the implementation of this innovation was part of the curricular activities in the University Teaching course, in the first half of 2012, to enrich the learning process of university professors from different colleges on campus

Since its origins, sociology has focused on the study of specific areas such as education, in order to become a science that not only explores the scientific studies, but is also specialized on the subject matter. This article presents an overview of the contributions of various theoretical European traditions regarding education. From the “theoretical inputs” presented, the reflection and theoretical proposal about the subject matter related to the sociology of education are re-defined, due to a seemingly lack of clarity or consensus among the authors. Mainly, this research attempts to analyze those core issues related to the understanding of the multiple interactions between society-education and vice versa, visible from sociology. As one of the main findings, it is argued that the traditionally named sociology of education encompasses three subject matters: sociology of education, pedagogical sociology and the sociology of the educational system. Although these lines of research are intertwined, its categorization facilitates the specific understanding of various aspects within the same subject matter.

El original no tiene resumen

En esta investigación se llevaron a cabo estudios analíticos y experimentales del comportamiento sísmico de cuatro especímenes, a escala 1/2.5, representativos del prototipo de una columna típica de un puente de concreto prefabricado con cimentación tipo candelero, construidos en los últimos años en la ciudad de México. Los especímenes estudiados fueron de dos tipos, el primero consistió en una columna con cimentación tipo candelero sin presfuerzo en la cimentación y el segundo tenía además cables de presfuerzo en la zona superior de la cimentación. Los estudios experimentales consistieron en aplicar cargas cíclicas reversibles a los especímenes empleando actuadores apoyados en un muro de reacción. Se compararon valores experimentales y calculados de la resistencia y deformación lateral de los especímenes. Se valuó la fuerza de fricción entre la columna y el candelero y se estudió su relevancia en el comportamiento de la conexión columna-cimentación. Con base en los resultados de este estudio se dan recomendaciones para el diseño de este tipo de cimentación tipo candelero para puentes.

Las políticas recientes de fomento a la vivienda en México han buscado optimizar los cada vez más escasos espacios disponibles en las grandes ciudades. Dentro de este contexto, empieza a considerarse cada vez más la construcción de edificios altos. En un edificio alto de mampostería, es muy posible que existan muros con relación de aspecto elevada. Un aumento en la relación de aspecto de un muro resulta en un cambio en su comportamiento ante cargas laterales, lo que lo lleva de una respuesta lateral dominada por corte a una dominada por flexión. Este artículo tiene como objetivo aportar elementos cualitativos y cuantitativos que permiten discutir la posibilidad de construir edificios altos de mampostería confinada en zonas sísmicas. Para ello se diseñó un edificio de 10 pisos ubicado en la Zona de Transición del Distrito Federal, y se llevó a cabo una serie de análisis estáticos no lineales para establecer las propiedades estructurales globales del edificio, y otra de análisis dinámicos no lineales para definir su desempeño sísmico. A partir de los resultados presentados se concluye que es posible construir edificios altos de mampostería en zonas sísmicas, y se identifican algunas de las acciones que deben emprenderse a corto plazo para hacer esto posible.

This paper focuses a study of the contributions of uncertainty and expanded uncertainty that take place in the calibration of a digital pressure gauge by direct comparison with a pressure balance. The work is performed based on GUM method, using analytical approach. Equation given by DKD-R 6-1 guideline for uncertainty analysis is discussed proposing an alternative model. It is aimed to determine the differences in the resulting uncertainty, according to the different platforms used, and how the standard uncertainty and assigned probability function (FDP) associated to different magnitudes of the model impact these differences. The development will be performed according to the GUM framework using the analytical methodology. In addition to this, the exercise is repeated in a comparative basis, using four calculation tools. Two of them are based on numerical approaches of the classical method, GUM Workbench software© and Kragten method, and the rest are based on the Supplement 1 to the Guide to the Expression of Uncertainty of Measurement, in one case by mean of R language and the second one using MCM Alchimia, application developed by one of the authors.

Solar energy is the promising font of the future. Direct conversion of the solar light into electricity using solar cells has many advantages, arising from the fact that does not generate contaminants or waste.Particularly, dye sensitized solar cells (DSSC) or Graetzel cells represent an alternative to conventional silicon one.In the three last decades DSSC have attracted great attention because of their low cost, the achievement of high efficiency conversion (12%), and good yields during prolonged light periods and under thermal stress.In this work, a mixture of natural dyes, anthocyanins from ceibo flower, is evaluated for their use as sensitizers. UV-visible measurements, cyclic voltammetry and electrochemical impedance spectroscopy are used to characterize these dyes.

The aim of this pilot study was to evaluate the bioaccumulation processes of Eichhornia crassipes exposed to a secondary effluent obtained from a Kraft pulp mill that drains the effluents into the River Uruguay, near Fray Bentos city, Rio Negro, Uruguay. The effluent was characterized before and after the Eichhornia culture, and organic halogens concentrations were determined in control and exposed specimens. Macroscopic changes were observed in the plant and the bioaccumulation routes were studied, the higher chlorinated organic compounds were found in the leaves (at a concentration of 9,4 µg/g by comparison to 2,1 µg/g of the control biomass). Nutrient removal was in the order of 90%. The results suggest that phytoremediation with floating plants can be advantageously alternative as a tertiary treatment methodology in subtropical and tropical countries to diminish the concentration of recalcitrant chlorinated organics and also to remove nitrate and phosphate from pulp mill effluents.

Shiga toxin-producing Escherichia coli (STEC) O157:H7 and no-O157:H7 have been identified as emerging foodborne pathogens responsible for an increasing number of outbreaks worldwide. Many foods have been associated to these outbreaks, mainly undercooked beef burgers. Due to the increasing production and consumption of burgers in our country, it is important to have a rapid technique to identify and isolate the most important STEC strains in foods matrixes.The objective of these investigation was to assess the sensitivity, specificity and limit detection for the screening of the most prevalent STEC in frozen raw beef burgers, using the "STEC Screening stx/eae " kit to detect the stx/eae genes and the "Panel 1 STEC E. coli O26, O111, O121" and "Panel 2 STEC E. coli O45, O103, O145" and "E. coli O157: H7 MP” (DuPont) kits for the detection of the different serogroups. The use of composed samples (wet pools), the recovery of each strain from the positives samples on selective media after specified inmunoconcentration and the detection of stx/eae virulence genes in isolates by PCR were also evaluated. We validated a technique that allows the detection of the mentioned STEC strains with limits of detection between 1-5 CFU in 65 grams of raw frozen hamburgers, using wet pools.