Las estrategias lectoras en la comprensión de problemas aritméticos en la educación primaria. (Original)

The work with mathematical problems constitutes an objective of special interest in primary education. Diverse authors agree in recognizing that the comprehension is the affected aspect more in the referred activity, who is based essentially on the elaboration of inferences. Before exposed he allows to deduce the necessity to favor the reading procedures in the process of comprehension of words problem. Consequently with it the objective of the work is to restructurereading procedures on the comprehension word problems in primary education.El trabajo con problemas aritméticos constituye un objetivo de especial interés en la enseñanza primaria. Diversos autores coinciden en reconocer que la comprensión es el aspecto más afectado en la referida actividad, la cual se basa esencialmente en la elaboración de inferencias. Lo antes expuesto permite deducir la necesidad de emplear estrategias lectoras en la instrumentación de su proceso de comprensión.Consecuentemente con ello el objetivo del artículo va dirigido areestructurar estrategias lectoras para la comprensión de problemas aritméticos en la educación primaria

La comprensión de problemas matemáticos en la enseñanza primaria / The comprehension of mathematic problems in primary school

El artículo da cuentas de los resultados de un proyecto de investigación titulado “Estudio de las causas de las dificultades en el aprendizaje de la comprensión textual desde un enfoque interdisciplinario en Camagüey, el cual culminó exitosamente en el año 2009. Tiene como objetivo proponer una metodología para la comprensión de los problemas matemáticos en la Enseñanza Primaria. La misma se diseñó teniendo en cuenta las características de estos textos, además de los postulados básicos de la teoría de la  compresión lectora y la solución de problemas. En la investigación se emplearon los métodos teóricos: análisis – síntesis, histórico – lógico y el inductivo – deductivo para la elaboración del marco teórico de la misma y la modelación y el enfoque de sistema para diseñar la metodología que se propone. Se utilizaron, además métodos del nivel empírico para constatar el dominio de los alumnos sobre la comprensión de problemas matemáticos; entre ellos se encuentran: la observación y el análisis de los productos de la actividad. El resultado fundamental es la metodología ya aludida.ABSTRACTThe paper describes the result of the research project “A study of causes of difficulties in learning comprehension from an interdisciplinary perspective in Camagüey. The main objective of that study is to propose a methodology for the comprehension of mathematic problems in primary school. In designing the methodology, the characteristics of this text variety, basic principle of the theory of reading comprehension and problem solving were taking into account. In this research work several theoretical methods were used—analysis-synthesis, historical-logical, inductive-deductive— to elaborate the theoretical framework, while modeling and system approach in the methodology construction. Additionally, empirical methods were used in order to assess the knowledge about comprehension of mathematic problems; among them observation and analysis of the activity results

La enseñanza y el aprendizaje de los contenidos matemáticos desde una perspectiva comunicativa /The mathematical contents teaching and learning from a communicative perspective

Objective: The paper aims at devising a didactic model for the treatment of mathematical contents, based on the assumption of learning as a process of textual comprehension and considering the texts as a cultural unit. Methods: Documentary analysis was used as an empirical method to construct the theoretical framework. Methods such analysis-synthesis, induction and deduction, and modeling were used from a functional, structural and systemic perspective to characterize the state of art and devise the proposal. Results: The proposed model is accompanied by a methodology, based on the resizing of the Mathematics lesson as a system of didactic components for the leadership of the processes of comprehension and production of meanings from mathematical texts (propositions, definitions and procedures). Conclusions: The effectiveness of the proposed model lays on the renew description of the Mathematics lesson components having the processes of comprehension and production of mathematics texts as a central axis.Objetivo: Se persigue ofrecer un modelo didáctico para el tratamiento de los contenidos matemáticos, el cual se sustenta en la asunción del aprendizaje como proceso de comprensión textual y el texto como unidad cultural. Métodos: Se empleó el análisis documental como método empírico para el estudio de la bibliografía especializada sobre el tema. Para la sustentación epistemológica y la configuración del modelo, fueron de utilidad los métodos teóricos siguientes: el análisis-síntesis, la inducción- deducción, la modelación y el sistémico estructural funcional. Resultado: El modelo propuesto posee implícitamente una metodología, basada en el redimensionamiento de la clase de Matemática como sistema de componentes didácticos para la dirección de los procesos de comprensión y producción de significados a partir de textos matemáticos (proposiciones, definiciones y procedimientos). Conclusión: El modelo didáctico que se propone es efectivo para la enseñanza y el aprendizaje de los contenidos matemáticos, pues redescribe las nuevas cualidades que adquiere la clase de Matemática como sistema de componentes que posee como eje central a los procesos de comprensión y producción de textos matemáticos

Evaluation of styrene-divinylbenzene beads as a support to immobilize lipases

A commercial and very hydrophobic styrene-divinylbenzene matrix, MCI GEL® CHP20P, has been compared to octyl-Sepharose® beads as support to immobilize three different enzymes: lipases from Thermomyces lanuginosus (TLL) and from Rhizomucor miehie (RML) and Lecitase ® Ultra, a commercial artificial phospholipase. The immobilization mechanism on both supports was similar: interfacial activation of the enzymes versus the hydrophobic surface of the supports. Immobilization rate and loading capacity is much higher using MCI GEL® CHP20P compared to octyl-Sepharose® (87.2 mg protein/g of support using TLL, 310 mg/g using RML and 180 mg/g using Lecitase® Ultra). The thermal stability of all new preparations is much lower than that of the standard octyl-Sepharose® immobilized preparations, while the opposite occurs when the inactivations were performed in the presence of organic co-solvents. Regarding the hydrolytic activities, the results were strongly dependent on the substrate and pH of measurement. Octyl-Sepharose ® immobilized enzymes were more active versus p-NPB than the enzymes immobilized on MCI GEL® CHP20P, while RML became 700-fold less active versus methyl phenylacetate. Thus, the immobilization of a lipase on this matrix needs to be empirically evaluated, since it may present very positive effects in some cases while in other cases it may have very negative ones. © 2014 by the authors.We gratefully recognize the support from the Spanish Government, grant CTQ2009-07568 and CTQ2013-41507-R and CNPq (Brazil). The predoctoral fellowships for García-Galán (Spanish Government) and dos Santos (CNPq, Brazil) are also recognized. The authors wish to thank Ramiro Martínez (Novozymes, Spain) for kindly supplying the enzymes used in this research. The help and comments from Ángel Berenguer (Instituto de Materiales, Universidad de Alicante) are kindly acknowledged. We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)Peer Reviewe

Combining aldolases and transaminases for the synthesis of 2‑amino-4-hydroxybutanoic acid

Amino acids are of paramount importance as chiral building blocks of life, for drug development in modern medicinal chemistry, and for the manufacture of industrial products. In this work, the stereoselective synthesis of (S)- and (R)-2-amino-4-hydroxybutanoic acid was accomplished using a systems biocatalysis approach comprising a biocatalytic one-pot cyclic cascade by coupling of an aldol reaction with an ensuing stereoselective transamination. A class II pyruvate aldolase from E. coli, expressed as a soluble fusion protein, in tandem with either an S- or R-selective, pyridoxal phosphate dependent transaminase was used as a catalyst to realize the conversion, with formaldehyde and alanine being the sole starting materials. Interestingly, the class II pyruvate aldolase was found to tolerate formaldehyde concentrations of up to 1.4 M. The cascade system was found to reach product concentrations for (S)- or (R)-2-amino-4-hydroxybutanoic acid of at least 0.4 M, rendering yields between 86% and >95%, respectively, productivities of >80 g L–1 d–1, and ee values of >99%.This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 635595 (CarbaZymes), the Ministerio de Economía y Competitividad (MINECO), the Fondo Europeo de Desarrollo Regional (FEDER) (grant no. CTQ2015-63563-R to P.C.), and COST action CM1303 Systems Biocatalysis.We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI).Peer reviewe

Search for dark matter produced in association with bottom or top quarks in √s = 13 TeV pp collisions with the ATLAS detector

A search for weakly interacting massive particle dark matter produced in association with bottom or top quarks is presented. Final states containing third-generation quarks and miss- ing transverse momentum are considered. The analysis uses 36.1 fb−1 of proton–proton collision data recorded by the ATLAS experiment at √s = 13 TeV in 2015 and 2016. No significant excess of events above the estimated backgrounds is observed. The results are in- terpreted in the framework of simplified models of spin-0 dark-matter mediators. For colour- neutral spin-0 mediators produced in association with top quarks and decaying into a pair of dark-matter particles, mediator masses below 50 GeV are excluded assuming a dark-matter candidate mass of 1 GeV and unitary couplings. For scalar and pseudoscalar mediators produced in association with bottom quarks, the search sets limits on the production cross- section of 300 times the predicted rate for mediators with masses between 10 and 50 GeV and assuming a dark-matter mass of 1 GeV and unitary coupling. Constraints on colour- charged scalar simplified models are also presented. Assuming a dark-matter particle mass of 35 GeV, mediator particles with mass below 1.1 TeV are excluded for couplings yielding a dark-matter relic density consistent with measurements