Cognitive processes associated with the professional development of the mathematics teacher

This paper proposes a model of professional development based on Sfard’s stages of interiorisation, condensation and reification, which highlights the teacher’s cognitive processes. The model is applied to the case study of a primary teacher participating in a collaborative project for professional development. This adaptation of Sfard’s stages proves to be of special value when interpreting the process of the teacher’s professional development from a cognitive perspective. Procesos cognitivos asociados al desarrollo profesional del profesor de matemáticas Este artículo propone un modelo de desarrollo profesional que pone de relieve los procesos cognitivos del profesor, en relación con las fases de interiorización, condensación y cosificación del trabajo de Sfard. El modelo se aplica al caso de una maestra que participa en un proyecto colaborativo de desarrollo profesional. La adaptación de las fases de Sfard se muestra valiosa para interpretar el proceso de desarrollo profesional de la maestra desde una perspectiva cognitiva. Handle: http://hdl.handle.net/10481/3509Nº de citas en WOS (2017): 1 (Citas de 2º orden, 0)Nº de citas en SCOPUS (2017); 1 (Citas de 2º orden, 1

Application of the Eco-Epidemiological Method in the Study of Leishmaniasis Transmission Foci

The study of transmission foci involves the clinical characterization of disease within a focus using active surveillance of human cases, characterization of the population group that is most frequently infected or at highest risk of becoming infected, diagnosis and treatment of infected people and identification of the conceptions, attitudes, beliefs and practices related to the disease. An entomological survey is necessary to determine the geographical distribution of species and incrimination of vector species, the ecological characteristics of the zone (macro-focus), times of the year and day of highest biting activity and places in homes in which the most frequent contact between the people and the vectors occurs. A survey of peri-domestic and wild mammals in the area is advisable to try to identify potential reservoir hosts. Using this information, it is feasible to design specific and accurate prevention and effective, rational and economic control measures and define the times of the year and locations in which these measures must be applied. In this chapter, a description of the application of the eco-epidemiological method to the study of leishmaniasis transmission foci is provided. A special emphasis is placed on the methodology, multidisciplinary work and analysis of findings

The response of the different soybean metallothionein isoforms to cadmium intoxication

Cadmium is a highly toxic heavy metal for both plants and animals. The presence of Cd in agricultural soils is of major concern regarding its entry into the food chain, since Cd compounds are readily taken up by plants, and accumulated in edible parts due to their high solubility. In this study, we first demonstrate the high capacity for Cd concentration of soybean grains. Consequently, we considered the study and characterization of the molecular determinants of Cd accumulation -such as metallothioneins (MT)- to be of major practical importance. We report here the first characterization of the soybean MT system, with the identification of nine genes (one of which is a truncated pseudogene), belonging to the four plant MT types. The most highly expressed of each type was chosen for further function analysis. All of them are expressed at high levels in soybean tissues: GmMT1, GmMT2 and GmMT3 in roots, shoots and seeds, and GmMT4 only in seeds. The corresponding recombinant soybean MTs, synthesized in Escherichia coli cells cultured in metal supplemented media, exhibit greater cadmium than zinc binding capacity. These results suggest a definite role of GmMTs in Cd(II) accumulation as one of the main responses of soybean to an overload of this metal.Fil: Pagani, María Ayelén. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Tomas, M.. Universidad de Barcelona; España. Universitat Autònoma de Barcelona; EspañaFil: Carrillo, Julieta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; ArgentinaFil: Bofill, R.. Universitat Autònoma de Barcelona; EspañaFil: Capdevila, M.. Universitat Autònoma de Barcelona; EspañaFil: Atrian, S. Universidad de Barcelona; EspañaFil: Andreo, Carlos Santiago. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Rosario. Centro de Estudios Fotosintéticos y Bioquímicos. Universidad Nacional de Rosario. Facultad de Ciencias Bioquímicas y Farmacéuticas. Centro de Estudios Fotosintéticos y Bioquímicos; Argentin

Use of cavity ring-down spectrometry to quantify 13C-primary productivity in oligotrophic waters

Cavity ring-down spectroscopy (CRDS) is a highly sensitive laser technique that allows the analysis of isotopic signals and absolute concentration of individual molecular species in small-volume samples. Here, we describe a protocol to quantify photosynthetic 13C-uptake rates of marine phytoplankton by using the CRDS technique (13C-CRDS-PP). We validated our method by comparing the 13C-PP rates measured between CRDS and isotope ratio mass spectrometry (IRMS) in samples with different carbon content (30–160 μgC). The comparison revealed that 13C-CRDS-PP rates were highly correlated with those obtained by IRMS (Spearman correlation coefficient, ρ = 0.95, p < 0.0001, n = 15), with a mean difference between the two estimates of +- 0.08 mgC m−3 h−1. Moreover, the slope of the relationship between CRDS and IRMS results was not significantly different from 1 (F = 0.03, p = 0.86), and the intercept did not differ from 0 (F = 1.4, p = 0.24), indicating that there was no bias in the CRDS relative to the IRMS-based measurements. A separate analysis also showed that despite the difference in volume and carbon content between samples (40 +- 10 μgC and 160 +- 40 μgC, respectively), the 13C-CRDS-PP technique provides similar results (Mann–Whitney test, U = 30.5, p = 0.90, n = 8). In addition, 13C-CRDS-PP rates measured along the Red Sea (~ 176 mgC m−2 d−1) agreed with 14C-based PP rates previously reported for similar locations. Thus, this study evidenced that the 13C-CRDS-PP method is sensitive enough to quantify carbon fixation rates in oligotrophic regions

What knowledge and conceptions mobilize future teachers analyzing a classroom video?

El uso del vídeo de sesiones de clase de Educación Primaria (EP) en la formación inicial del maestro aporta realismo a las discusiones teóricas de las aulas de magisterio, contribuyendo a la vinculación entre la teoría y la práctica sobre la base de procesos reflexivos que ayudan a trascender los habituales comentarios genéricos de los estudiantes para maestro (EPM). El objetivo de este estudio es identificar las concepciones sobre la enseñanza y el aprendizaje de las matemáticas así como el conocimiento matemático para la enseñanza (particularmente el conocimiento de matemáticas y la enseñanza y el conocimiento de matemáticas y los estudiantes) que un grupo de EPM pone en juego cuando observa un vídeo de EP. Mediante un diseño de investigación consistente con un experimento de enseñanza (Steffe y Thompson, 2000) (en el que un diseño instruccional, orientado a los EPM, acerca de la introducción del concepto de división, se va refinando a través de sucesivos ciclos de implementación y análisis), se pone de relieve cómo el análisis de situaciones de enseñanza en EP promueve el cuestionamiento de los EPM.The use of the Primary Education (PE) class sessions video in the initial training of teachers provides realism to the theoretical discussions of Master’s degree classrooms, contributing to the link between theory and practice on the basis of reflective processes that help to transcend the normal general comments of teacher students (TS). The objective of this study is to identify the conceptions for the teaching and learning of mathematics, as well as the mathematical knowledge for teaching (particularly the knowledge of mathematics and the teaching and knowledge of mathematics and students) that a group of TS use when observing a PE video. Using a research design consistent with a teaching experiment (Steffe and Thompson, 2000) (in which an instructional design, aimed at TS, regarding the introduction of the concept of division, is refined by means of successive cycles of implementation and analysis), the way the analysis of teaching situations in PE promotes the questioning of TS is highlighted.O uso de vídeos de sessões de aula de Educação Primária (EP) na formação inicial do professor oferece realismo às discussões teóricas sobre as aulas de magistério, contribuindo para a vinculação entre a teoria e a prática sobre a base de processos reflexivos que ajudam a transcender os habituais comentários genéricos dos estudantes para professores (EPM). O objetivo deste estudo é identificar as concepções sobre o ensino e a aprendizagem da matemática, assim como o conhecimento matemático para o ensino (particularmente o conhecimento de matemática e o ensino e o conhecimento de matemática e dos estudantes) que um grupo de EPM põe em jogo quando observa a um vídeo de EP. Através de uma criação de pesquisa consistente com um experimento de ensino (Steffe e Thompson, 2000), destaca-se como a análise de situações de ensino em EP promove o questionamento dos EPM.L’utilisation de la vidéo pour une classe d’élèves en école primaire (EP) durant la formation des futurs instituteurs confère un certain réalisme aux discussions théoriques qui ont lieu dans les cours de formation des instituteurs (l’équivalent en France des IUFM) en contribuant à la création de liens entre théorie et pratique basés sur des processus réflexifs qui permettent aux étudiants d’aller au-delà des habituels commentaires généraux. L’objectif de la présente étude consiste à identifier les conceptions sur l’enseignement et l’apprentissage des mathématiques ainsi qu’à s’interroger sur la connaissance mathématique pour l’enseignement (en particulier, la connaissance des mathématiques et l’enseignement des mathématiques et les étudiants) qu’un groupe de futurs instituteurs utilise lorsqu’il observe une vidéo conçue pour l’école primaire. Grâce à un travail de recherche qui va de pair avec une expérience sur l’enseignement (Steffe et Thompson, 2000) (dans lequel un travail propre à l’enseignement conçu pour les futurs instituteurs portant sur l’introduction du concept de division s’affine de plus en plus au fur et à mesure que des cycles successifs de mises en oeuvre et d’analyse sont utilisés), on montre comment l’analyse de situations en école primaire suscite le questionnement des futurs instituteurs

New insights into the fossil record of the turtle genus Chelus Duméril, 1806 including new specimens with information on cervicals and limb bones

Matamata turtles (Chelus Duméril, 1806) are composed of two extant species, Chelus fimbriata ­Schneider, 1783 and Chelus orinocensis Vargas-Ramírez, Caballero, Morales-Betancourt, Lasso, Amaya, Martínez, Silva-Viana, Vogt, Farias, Hrbek, Campbell & Fritz, 2020, inhabitants of the main freshwater drainages of northern South America. The systematics and palaeobiogeography of Chelus is still unresolved. Here, we describe several new fossil specimens from the Late Miocene of Urumaco (Venezuela) and Tatacoa (Colombia). The fossils are mostly complete, articulated shells that allow reestablishing validity of two extinct taxa, Chelus colombiana Wood, 1976 and Chelus lewisi Wood, 1976. One of the specimens of C. lewisi from Urumaco represents the first record within the genus for which autopodial bones (a left manus) and additional limb bones are preserved together with ashell, demonstrating evolutionary conservatism in limb anatomy for the genus. The specimen comes from the Socorro Formation, representing the earliest so far known record of Chelus for the Urumaco sequence. Additionally, one specimen from Tatacoa is the first fossil for which cervical and pectoral girdle elements are preserved. Phylogenetic analysis supports the existence of two separate clades inside of Chelus, one formed by the extinct species and the other by the extant ones

Eficacia y eficiencia en la enseñanza media chilena desde los datos SIMCE 1994,1998 y 2001

En el artículo se aborda la calidad de la educación en el 2º Medio mediante el análisis de la eficiencia de los colegios y liceos. Se utilizan los datos de la prueba nacional SIMCE de 2º Medio de 1994, 1998 y 2001. La eficiencia se calcula mediante regresión lineal múltiple de la eficacia (logro escolar = resultados SIMCE), con control de variables de input: inversión por alumno, nivel educativo de los padres y vulnerabilidad educativa. Los resultados SIMCE dependen en un 69% de las tres variables de input estudiadas, siendo imputable a los centros escolares en un 31 %. Las diferencias en eficiencia entre las redes pública y privada apenas alcanza a 1.75 puntos promedio (hay que tener en cuenta que no se ha podido controlar la selección de alumnos por los centros). Los centros financiados con fondos públicos son los que muestran un progreso en su eficiencia en el estudio longitudinal, especialmente los municipales. Los resultados apuntan a que el mercado en la educación no está justificado empíricamente para mejorar la calidad y eficiencia en la educación, aunque si para generar negocios con la educación

Construcción de conocimiento sobre características de aprendizaje de las Matemáticas a través del análisis de vídeos

En este artículo abordamos la construcción de conocimiento sobre las características de aprendizaje matemático. Nos centramos en cómo tres estudiantes para maestro analizan un video en el que una maestra de primaria trabaja contenidos de geometría con sus alumnos. Mostraremos cómo la discusión del video da a estos tres estudiantes para maestro la oportunidad de mirar profesionalmente el aprendizaje de los alumnos que en él aparecen, movilizando lo aprendido en cursos previos y creando la posibilidad de generar nuevo conocimiento a través de sus intentos por comprender a los alumnos

Biofuels from Diethyl Carbonate and Vegetable Oils for Use in Triple Blends with Diesel Fuel: Effect on Performance and Smoke Emissions of a Diesel Engine

The main objective of this work is to contribute to a gradual replacement process of fossil diesel (D) with biofuels composed by diethyl carbonate (DEC) and either sunflower or castor oil, as straight vegetable oils (SVOs). DEC is a very interesting candidate as an oxygenated additive not only because of its low price and renewable nature, but also its favorable fuel properties, such as very low kinematic viscosity, high cetane number, high oxygen content, rich cold flow properties and good miscibility with fossil diesel and vegetable oils. In this work, the more suitable DEC/SVO biofuels are chosen based on kinematic viscosity, according to the European normative. Additionally, the most relevant physical–chemical properties of (bio)fuels such as density, calorific value, cloud point, pour point and cetane number are determined. The influence of DEC on engine performance and exhaust emissions is analyzed by fueling a conventional Diesel engine with the different D/DEC/SVO triple and DEC/SVO double mixtures. The tests results are also compared with commercial diesel. From the results, it is concluded that Diesel engine fueled with the blends studied exhibits an excellent performance in terms of power output, very similar to diesel. Additionally, the use of these blends can remarkably decrease smoke emissions down to 98%, with respect to fossil diesel. The addition of DEC shows a significant improvement in cold flow properties of fuel mixtures in the exchange of a slightly higher brake specific fuel consumption (BSFC) than diesel. Interestingly, the pure biofuels composed by DEC and SVO allow for a suitable engine operation and achieve the lowest emissions, which means these blends can be successfully employed in current engines without adding fossil diesel, i.e., their use entail a 100% renewability

Evaluation of Dimethyl Carbonate as Alternative Biofuel. Performance and Smoke Emissions of a Diesel Engine Fueled with Diesel/Dimethyl Carbonate/Straight Vegetable Oil Triple Blends

Dimethyl carbonate (DMC) is an interesting blending component for diesel fuel (D) owing to the high oxygen content (53 wt.%) and the absence of C–C bonds in its structure. Moreover, DMC can be produced from CO2 and methanol, which provides a renewable way to reduce anthropogenic CO2. This research has been addressed to assess the use of DMC as a solvent of sunflower oil (SO) and castor oil (CO), with the purpose of obtaining biofuels that can replace fossil diesel as much as possible. The blending of DMC with straight vegetable oils (SVOs) reduces their high viscosity, allowing their usage as drop-in biofuels without chemical treatments. Based on viscosity requirements of European Standard EN 590, the optimal DMC/SVO double blends have been tested as direct biofuels by themselves or mixed with fossil diesel in D/DMC/SVO triple blends. Relevant physico-chemical properties of fuels have been analyzed. Engine parameters such as power output, brake-specific fuel consumption (BSFC) and soot emissions have been studied to determine the effect of new biofuels on efficiency of a diesel engine. An outstanding engine efficiency is shown by the studied D/DMC/SVO triple blends, either with SO or CO as an SVO. The low calorific value of DMC is the main reason for reduction in power and BSFC, as the amount of diesel in the triple blends is reduced. Experimental results demonstrate that the use of these biofuels allows the replacement of up to 40% of fossil diesel, without compromising the power and BSFC of the engine, and accomplishing optimal cold flow properties and a marked drop in exhaust emissions