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

El objetivo principal es diseñar un dispositivo óptico sensor sumergible que permita mayor precisión y sensibilidad en técnicas volumétricas de determinación química cuyo punto final depende de la coloración de la solución analizada. Este sensor además de eliminar la subjetividad en la apreciación del operador, podrá ser utilizado en el control automático de las técnicas de análisis que se hayan evaluado. Dado que existen diversas técnicas analíticas que difieren en el medio en que se desarrollan y en el color del punto final, se analizará la posibilidad de diseñar el dispositivo con la capacidad de emitir en diferentes rangos de longitud de onda y resistente a la acción de agentes ácidos y básicos (álcalis), Esto aumentará la versatilidad del sensor desarrollado.

Our main concern is that the learning of mathematics could be experienced out of context. Because of this, we move from building the math foundations of our undergraduate students to their technical preparation; by this way, we establish a relevant math background in them. This work was developed inside the biochemical engineers’ community and it studies the technical practice of the spectrophotometry with emphasis in the calibration curve topic. The analysis of the ways in which the practice of the spectrophotometry is done was made under the consideration of the next dimensions: procedures, intentions, tools and the arguments of the ones who used them. This dimensions are uncover by the way in which the one who apply the practice of the spectrophotometry ties together the mathematical model of the physical phenomenon with the model obtained in the practice; the consequence is the setting of a model dipole. It is through the use of deconstruction, as an approximation method, that the practice of spectrophotometry has been characterized with the objective to elaborate a learning design. By applying this learning design, the acting of the students in the construction of the calibration curve is shown as well as the evidences of how they identify the necessity to adjust the data in a linear manner articulating a graphical model, obtaining different ways of prediction by using the three rules, the algebraic model or the graphical one. It is in this way that the student can achieve a strengthening of his interpretation of the practice of the spectrophotometry, reconstructing its practice.

See the result of the application of a didactic situation with secondary students to analyze how to understand the notion of similarity with the use of didactic material. The situation is based on the Theory of Didactic Situations with activities of construction of geometric figures with the use of tangram as material of didactic. The goal is that students generate a geometric representation of similarity and conjecture the idea of ​​reason. The results of the strategies with the use of the material to generate explanations on the notion of similarity.  

This paper presents the problem of the training of professionals from a very particular view of Educational Mathematics. This problem is aggravated when speaking of a very particular community as the engineering community. It is known that the need to have a greater number of graduates in this area is now detected and due to a series of difficulties this need has not been fully covered. In particular, we would like to present the efforts that have been made since Mathematics Education, from the teaching and learning approach of Mathematics through Modeling and Simulation but above all in these last years of the way in which a group of research professors Latin Americans have decided to contribute from different theoretical perspectives to give elements of answers and educational proposals to this problem. We intend to address in this paper about these three views: the relationship Mathematics and Engineering; the teaching proposal through Modeling and finally on challenges and first actions through the collaboration between different Latin American realities.

The present study aims to favor the processes of learning and implementation of mathematical modeling notion pre-service and in-service teachers’ training. In order to achieve so, we describe a proposal which main goal is teachers experiment and solve a situation based on mathematical modeling process by taking a student’s role. We first discuss the theoretical aspects that support the proposal and present the two phases that make up the study. The results exhibit a design of a situation that takes place in a biological context whose tasks are properly inscribed in the phases of mathematical modeling process. In our example of situation, a technological tool is incorporated with the purpose of assisting the transit between the set out of the problem and the production of mathematical models.

This article focuses on the emotions of the mathematics teacher, aims to visualize the affective variables in the teaching of mathematics and lead the reader to reflect on the importance of these. In order to reach the goal purpose we use the emotional knowledge of a novice teacher of mathematics who teaches second grade in Secondary Education. Through the techniques of video recording and the interview we have identified some of the emotions that they experience during their practice and the triggers of them, which has allowed us to reaffirm the role of emotions as the motor of action and their relationship with professional knowledge.

Abrirse paso en el mundo de las publicaciones científicas en México es una tarea compleja, más si se trata de una que forme parte de un proyecto académico desarrollado al interior de una asociación civil sin fines de lucro –como lo es la Red de Investigadores Educativos Chihuahua–, donde los recursos económicos son escasos y la sustentabilidad financiera depende de la buena voluntad de sus socios. La tendencia de las publicaciones científicas en nuestro país es de migración del formato impreso al electrónico. Las plataformas editoriales de acceso abierto, como el Open Journal Systems (OJS), se convierten en mecanismos que facilitan la gestión editorial, sistematizando el envío de artículos, el registro de pares dictaminadores, el seguimiento de evaluaciones, la indexación en bases de datos y la transferencia de artículos en formatos para su publicación en otras plataformas.

Resumen. Numerosos trabajos regionales o locales han propuesto el reconocimiento de unidades biogeográficas de distintos rangos (biocoremas) basadas sobre la distribución de los moluscos bivalvos para el Jurásico, pero no existía una síntesis a nivel mundial. Este trabajo es una revisión de las más significativas de esas propuestas, en un intento de lograr una síntesis de los patrones biogeográficos globales desde el Jurásico Temprano al Tardío, mientras se producían cambios sustanciales en la paleogeografía de la Tierra y los patrones de circulación oceánica como resultado de la disgregación de Pangea. Se hace también un breve análisis de la evolución en el tiempo y el espacio de cada una de las principales unidades reconocidas y de sus relaciones. Estos biocoremas pueden agruparse en tres unidades de primer orden que han tenido continuidad en el tiempo: Boreal, Tethys y Austral. Las unidades revisadas aquí han sido reconocidas y caracterizadas de forma muy heterogénea por los distintos autores, pero los criterios básicos más utilizados incluyen desde el grado de endemismo y la diversidad relativa, hasta las afinidades paleobiogeográficas de los taxones a nivel genérico. Los patrones de distribución de los bivalvos jurásicos no solamente son claves para entender cuestiones puramente biogeográficas, sino que han sido utilizados como argumento y evidencia en discusiones de índole paleogeográfica (como el establecimiento de corredores oceánicos, o patrones de circulación marina superficial), e incluso son pruebas de peso para la discusión de tópicos paleotectónicos, como la localización de terrenos desplazados y la deriva continental.PALABRAS CLAVE: Paleobiogeografía. Jurásico. Bivalvia. Biocoremas. Provincias biogeográficas. Bipolaridad. Gradientes latitudinales.Abstract. A REVIEW OF JURASSIC MARINE WORLDWIDE BIOCHOREMAS BASED ON THE DISTRIBUTION OF BIVALVE MOLLUSKS. Local and regional papers analyzing the distribution of Jurassic bivalves and proposing new palaeobiogeographic units of various ranks are numerous, but a worldwide synthesis was lacking. This paper is a review of those proposals with the aim to obtain a coherent synthesis of the global biogeographic patterns from Early to Late Jurassic times, when significant changes in the Earth paleogeography and oceanic circulation took place as the result of the breakup of Pangea. A brief account of the evolution in time and space of the recognized units and their relationships is also made. The biochoremas can be grouped into three first order units which had temporal continuity: Boreal, Tethys and Austral Realms. The units analysed here were recognized and characterized in very different grounds by their authors; the most commonly used criteria are degree of endemism, relative diversity and palaeobiogeographic affinities of bivalve genera. The patterns of Jurassic bivalve distribution are key to understand general biogeographic issues, but they were also used as evidence in palaeogeographic discussions (such as the establishment of seaways and changing patterns of superficial water circulation); they are even arguments in some palaeotectonic issues, such as the localization and history of displaced terranes, and continental drift.KEY WORDS: Palaeobiogeography. Jurassic. Bivalvia. Biocoremas. Biogeographic provinces. Bipolarity. Latitudinal gradients.

An album of photographs in the Kansas University Natural History Museum found together with the Patagonian fossils collected by Handel T. Martin in 1904 was assumed in a recent publication to have been assembled by Martin. It comprises 193 numbered pages and 580 photographs of prepared fossil vertebrate specimens, some labeled as from the Museo de La Plata and others, without labels, which were assumed as having been in F. Ameghino’s private fossil collection. However, archival evidence in the Yale Peabody Museum indicates that the album is most likely the original copy of the photographic album assembled by William B. Scott during his visit to Argentina in 1901 to examine fossil specimens from Patagonia in the museums of La Plata and Buenos Aires, and in Ameghino’s collection. It represents an important record of the specimens present at these institutions and in possession of Ameghino near the turn of the last century, a period during which those fossils aroused considerable scientific interest and were in very high demand among researchers and academic institutions, but marked as well by severe conflicts between F. Ameghino and the Director of the Museo de La Plata, F.P. Moreno.  As a consequence the collections were subjected to considerable turmoil and many important specimens can no longer be located. The album provides visual references for these specimens and facilitates systematic and taxonomic research by helping to evaluate which specimens were used to erect numerous taxa and which were analyzed by other researchers who published on such remains.

The stratigraphic reinterpretation of a controversial paleontological site such as the Quequén Salado River banks allowed refinement of the biochron of the caenolestine marsupial Pliolestes tripotamicus Reig. Two fossil bearing units were proposed for these exposures: a lower one, AUA (Huayquerian) and an upper one, AUB (Montehermosan). P. tripotamicus is found in AUA, but not in AUB or in typical Montehermosan and Chapadmalalan localities, which suggests that this taxon was not part of the Montehermosan–Chapadmalalan assemblages. The other species, P. venetus Goin et al. (Huayquerian), and Caenolestidae n. sp. aff. P. tripotamicus (Chasicoan) indicate the genus was restricted to the Chasicoan–Huayquerian stages/ages. The retraction of the caenolestines toward the Andean Region (where they live today) would have taken place at the beginning of the Pliocene, probably more related to environmental changes than to competence with cricetid rodents as first proposed.