La elaboración de preguntas en la enseñanza de la comprensión de problemas matemáticos

El artículo que se presenta tiene como objetivo ofrecer una metodología para la elaboración de preguntas que desarrollen la comprensión de problemas matemáticos en la Enseñanza Primaria. El principal aporte de la investigación a la Didáctica de la Matemática reside en la metodología que se ofrece, la cual se sustenta en la reconceptualización de los problemas matemáticos como textos y la asunción de la resolución de problemas como proceso de comprensión textual. La efectividad de la metodología fue valorada mediante su implementación en la práctica educativa de la Escuela Vocacional de Arte "Luis Casas Romero" durante el curso 2010 – 2011

Hydrogen Peroxide in Biocatalysis. A Dangerous Liaison

Hydrogen peroxide is a substrate or side-product in many enzyme-catalyzed reactions. For example, it is a side-product of oxidases, resulting from the re-oxidation of FAD with molecular oxygen, and it is a substrate for peroxidases and other enzymes. However, hydrogen peroxide is able to chemically modify the peptide core of the enzymes it interacts with, and also to produce the oxidation of some cofactors and prostetic groups (e.g., the hemo group). Thus, the development of strategies that may permit to increase the stability of enzymes in the presence of this deleterious reagent is an interesting target. This enhancement in enzyme stability has been attempted following almost all available strategies: site-directed mutagenesis (eliminating the most reactive moieties), medium engineering (using stabilizers), immobilization and chemical modification (trying to generate hydrophobic environments surrounding the enzyme, to confer higher rigidity to the protein or to generate oxidation-resistant groups), or the use of systems capable of decomposing hydrogen peroxide under very mild conditions. If hydrogen peroxide is just a side-product, its immediate removal has been reported to be the best solution. In some cases, when hydrogen peroxide is the substrate and its decomposition is not a sensible solution, researchers coupled one enzyme generating hydrogen peroxide “in situ” to the target enzyme resulting in a continuous supply of this reagent at low concentrations thus preventing enzyme inactivation. This review will focus on the general role of hydrogen peroxide in biocatalysis, the main mechanisms of enzyme inactivation produced by this reactive and the different strategies used to prevent enzyme inactivation caused by this “dangerous liaison”.This work has been supported by grant CTQ2009-07568 from Spanish Ministerio de Ciencia e Innovación. A. Berenguer-Murcia thanks the Spanish Ministerio de Ciencia e Innovación for a Ramon y Cajal fellowship (RyC-2009-03813). Mr. Hernandez is a holder of a MAEC-AECID fellowship

Non-relativistic torque and Edelstein effect in noncollinear magnets

The Edelstein effect is the origin of the spin-orbit torque: a current-induced torque that is used for the electrical control of ferromagnetic and antiferromagnetic materials. This effect originates from the relativistic spin-orbit coupling, which necessitates utilizing materials with heavy elements. Here we show that in magnetic materials with non-collinear magnetic order, the Edelstein effect and consequently also a current-induced torque can exist even in the absence of the spin-orbit coupling. Using group symmetry analysis, model calculations, and realistic simulations on selected compounds, we identify large classes of non-collinear magnet candidates and demonstrate that the current-driven torque is of similar magnitude as the celebrated spin-orbit torque in conventional transition metal structures. We also show that this torque can exist in an insulating material, which could allow for highly efficient electrical control of magnetic order.Comment: 11 pages, 5 figue

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

The Educational Inclusion of School Children with a Diagnosis of Autism Spectrum Disorder, Current Situation, Reflections and Challenges in Cuba

Educational inclusion requires the improvement of the work carried out by teachers, specialists and families in order to meet the needs of children, adolescents and young people with Autism Spectrum Disorder (ASD). The comprehensive education given to these students with ASD based on the inclusive policies that are being developed is a great challenge, and when considering the high expectations of an educated population like Cuba’s. The purpose of this paper is to review the pedagogical work structured on a set of principles for ASD students. For this purpose, the application and continuous use of interaction techniques that are put into practice in daily life favor learning, socialization, adaptation of their behaviors, social interrelations, and knowledge of the environment of the children with ASD. The intensity and long duration of the interventions, the cooperative intervention, precocity, the ecological principle, priority to communication and socialization, the multisensory principle, and the use of alternative facilitating systems and individualization during intervention can become guidelines for the pedagogical work the ASD learners

Fuzzy system of irrigation applied to the growth of Habanero Pepper (Capsicum chinense Jacq.) under protected conditions in Yucatan, Mexico

Agriculture is the largest user of water worldwide by using about 70 percent of total consumption. The world food production depends on the availability of water, considering factors such as demographic and climate change, so the use of efficient irrigation is necessary to apply the correct amount of water to crops. The traditional irrigation systems generally program their scheme based on measurements made at Class A evaporimeter pan. In this paper an irrigation scheme defined by an algorithm that automates the amount of water supplied is presented, it considers the consumption of habanero pepper crop, and a fuzzy system evaluates the necessary duration of irrigation. The climatic variables considered are temperature, relative humidity, and soil moisture. The algorithm was programmed in a microcontroller Atmel 328p included in Arduino platform, with the addition of a ZigBee wireless system that allows for monitoring through a PC. The climatic variables were inserted into the fuzzy system by sets of trapezoidal and triangular form and a Mamdani type inference mechanism in which the knowledge of an expert is registered through the fuzzy rules. The system was applied to a habanero pepper crop at Conkal Institute of Technology in Yucatan, Mexico.Peer ReviewedPostprint (published version

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

Immobilization of Proteins in Poly-Styrene-Divinylbenzene Matrices: Functional Properties and Applications

Supports based on poly-styrene-divinylbenzene (PSD) are commercially available since a long time ago. However, they are not commonly used as enzyme immobilization matrices. The main reason for this lies in the negative effect of the very hydrophobic surface on enzyme stability that produces the instantaneous enzyme inactivation in many instances. However, they have recently regained some impact in enzyme immobilization. They are easy to modify, and have been prepared with different modifiers. We will pay special attention to the coating of these supports with ionic liquids, which permits to have the ionic liquid phase anchored to the solid and modulate the enzyme properties without risk of losing these expensive and potentially toxic compounds. Thus, this review will present the covalent or physical immobilization of enzymes on PSD supports, submitted to different modifications. Moreover, lipases immobilized via interfacial activation on some naked PSD supports have shown some unexpected improvement in their catalytic properties, with uses in reactions like hydrolysis, esterification or transesterification.We gratefully recognize the support from the Spanish Government, CTQ2013-41507-R and CNPq (Brazil). The predoctoral fellowships for Ms. García-Galán (Spanish Government), Mr K. Hernandez (I3P-CSIC) and Mr dos Santos (CNPq, Brazil) are also recognized. ). Á. Berenguer-Murcia thanks the Spanish Ministerio de Ciencia e Innovacion for a Ramon y Cajal fellowship (RyC-2009-03813)