Análisis de fenómenos didácticos vinculados al estudio del álgebra: aspectos de una metodología de investigación

A partir del análisis didáctico de distintas organizaciones matemáticas puntuales de la enseñanza media chilena que pertenecen al ámbito algebraico, se pudo postular la presencia de ciertas regularidades didácticas de aparente generalidad. En la presente comunicación se mostrará la metodología utilizada para realizar la constatación empírica sobre la presencia o no de dichas regularidades, la que se encuentra basada en la teoría antropológica de lo didáctico (TAD). En particular, se describirá el proceso de elaboración y posterior análisis del instrumento utilizado para tal propósito. El análisis de los resultados concluye con la aplicación de un programa informático de análisis implicativo (CHIC). De esta forma, además de corroborar la mayoría de las hipótesis planteadas, este análisis permitió detectar ciertos aspectos del trabajo matemático de los estudiantes que en una primera versión del análisis no parecieron evidentes. El artículo muestra algunos resultados obtenidos dentro de un trabajo de tesis de magíster de la Universidad Católica de Valparaíso, y que estamos realizando en el marco de los proyectos DYCIT Nº 26-9933ES y FONDECYT Nº 1020342 de Chile.

El proceso de modelización en el aula: buscando un modelo geométrico para el corazón

Este trabajo se propone compartir y discutir el resultado de una investigación en la que se utilizó la modelización del cálculo del volumen del ventrículo izquierdo del corazón como instrumento en el proceso de enseñanza-aprendizaje de las matemáticas para enriquecer y mejorar nuestra práctica cotidiana, realizada con alumnos que cursan el nivel medio. El modelo proviene de aproximaciones realizadas para poder entender mejor la naturaleza y severidad de las afecciones cardíacas y mostrar con una visión simplificada aspectos de diagnóstico médico. (Pichel y otros, 1988). Otorgar significatividad a conceptos como área y volumen. El proceso de modelización llevado a cabo en el aula siguió la secuencia planteada por Sallett Biembengut y Hein (1999). Esto dio origen a la búsqueda de información; a partir del análisis de la misma y de la elección de una figura se elaboraron actividades con el objeto de modelizarlo a través de alguna cuádrica. Esta experiencia se constituyó en un medio eficaz para la motivación ya que los alumnos optaron por un desarrollo activo, demostrando gran interés al realizar las actividades dado que trabajaron con situaciones reales, buscando respuestas en la matemática a problemas concretos de otras ciencias.

Las actividades de modelación y simulación para la construcción de significados del cálculo

En este reporte de investigación se presentan los avances de un proyecto acerca de las formas de construcción de conocimiento matemático que proporcionan experiencias de aprendizaje basadas en actividades de simulación y modelación en el estudio de situaciones de la variación y de la acumulación de cantidades que varían continuamente. En la investigación se toma como referencia la aproximación socioepistemológica. Bajo ese paradigma se concibe el cálculo como el cuerpo de conocimientos que permite el estudio de los fenómenos de variación y la modelación se concibe como una forma de construir conocimiento matemático que pertenece a las prácticas sociales. Se presentan aquí las primeras exploraciones en un contexto del estudio del movimiento. La forma de trabajar las representaciones asociadas al movimiento es con el uso de sensores y de transductores que transforman la información en conjuntos de datos que diversos programas manipulan mostrando representaciones gráficas en calculadoras.

Experiencias en el diseño e implementación de cursos de cálculo usando web

En este trabajo presentaremos el diseño de cursos de cálculo diferencial e integral de una y varias variables que siguen una estrategia combinada de enseñanza presencial y de aprendizaje en línea basados en la metodología de diseño instruccional elaborado en el Sistema ITESM (ITESM,1995) En el diseño hemos considerado el análisis de la materia, la planeación del curso: objetivos, contenidos, actividades, evaluaciones, etc. (Rico, 1998) y la integración del curso (sitio WEB y actividades en el aula). También mostraremos ejemplos de actividades de los cursos.

Experiencias en desarrollos tecnológicos accesibles: Experiencia Ecuador

Presentación de la conferencia "Experiencias en desarrollos tecnológicos accesibles: Experiencia Ecuador" impartida en la III Jornada de Accesibilidad Digital 2016 (http://tecdigital.tec.ac.cr/servicios/accesibilidad3/) celebrada del 25 al 28 de octubre de 2016 y organizada por el Instituto Tecnológico de Costa Rica (TEC).

Insulator-to-metal transition in vanadium supersaturated silicon: variable-range hopping and Kondo effect signatures

We report the observation of the insulator-to-metal transition in crystalline silicon samples supersaturated with vanadium. Ion implantation followed by pulsed laser melting and rapid resolidification produce high quality single-crystalline silicon samples with vanadium concentrations that exceed equilibrium values in more than 5 orders of magnitude. Temperature-dependent analysis of the conductivity and Hall mobility values for temperatures from 10K to 300K indicate that a transition from an insulating to a metallic phase is obtained at a vanadium concentration between 1.1 × 10^(20) and 1.3 × 10^(21) cm^(−3) . Samples in the insulating phase present a variable-range hopping transport mechanism with a Coulomb gap at the Fermi energy level. Electron wave function localization length increases from 61 to 82 nm as the vanadium concentration increases in the films, supporting the theory of impurity band merging from delocalization of levels states. On the metallic phase, electronic transport present a dispersion mechanism related with the Kondo effect, suggesting the presence of local magnetic moments in the vanadium supersaturated silicon material.

Improving safety and establishing episomal maintenance of Adeno-associated viral vectors

Adeno-associated viral (AAV) vectors are among the most widely used gene transfer systems in basic and pre-clinical research and have been employed in more than 160 clinical trials. AAV vectors are commonly produced in producer cell lines like HEK293 by co-transfection with a so-called vector plasmid and one (in this work) or two so-called helper plasmids. The vector plasmid contains the transgene cassette of interest (TEC) flanked by AAV’s inverted terminal repeats (ITRs) which serve as packaging signals, whereas the helper plasmid provides the required AAV and helper virus functions in trans. A pivotal aspect of AAV vectorology is the manufacturing of AAV vectors free from impurities arising during the production process. These impurities include AAV vector preparations that contain capsids containing prokaryotic sequences, e.g. antibiotic resistance genes originating from the producer plasmids. In the first part of the thesis we aimed at improving the safety of AAV vectors. As we found that encapsidated prokaryotic sequences (using the ampicillin resistance gene as indicator) cannot be re-moved by standard purification methods we investigated whether the producer plasmids could be replaced by Minicircles (MCs). MCs are circular DNA constructs which contain no functional or coding prokaryotic sequences; they only consist of the TEC and a short sequence required for production and purification. MC counterparts of a vector plasmid encoding for enhanced green fluorescent (eGFP) protein and a helper plasmid encoding for AAV serotype 2 (AAV2) and helper Adenovirus (Ad) genes were designed and produced by PlasmidFactory (Bielefeld, Germany). Using all four possible combinations of plasmid and MCs, single-stranded AAV2 vectors (ssAAV) and self-complementary AAV vectors (scAAV) were produced and characterized for vector quantity, quality and functionality. The analyses showed that plasmids can be replaced by MCs without decreasing the efficiency of vector production and vector quality. MC-derived scAAV vector preparations even exceeded plasmid-derived preparations, as they displayed up to 30-fold improved transduction efficiencies. Using MCs as tools, we found that the vector plasmid is the main source of encapsidated prokaryotic sequences. Remarkably, we found that plasmid-derived scAAV vector preparations contained a much higher relative amount of prokaryotic sequences (up to 26.1 %, relative to TEC) compared to ssAAV vector preparations (up to 2.9 %). By replacing both plasmids by MCs the amount of functional prokaryotic sequences could be decreased to below the limit of quantification. Additional analyses for DNA impurities other than prokaryotic sequences showed that scAAV vectors generally contained a higher amount of non-vector DNA (e.g. adenoviral sequences) than ssAAV vectors. For both, ssAAV and scAAV vector preparations, MC-derived vectors tended to contain lower amounts of foreign DNA. None of the vectors tested could be shown to induce immunogenicity. In summary we could demonstrate that the quality of AAV vector preparations could be significantly improved by replacing producer plasmids by MCs. Upon transduction of a target tissue, AAV vector genomes predominantly remain in an episomal state, as duplex DNA circles or concatemers. These episomal forms mediate long-term transgene expression in terminally differentiated cells, but are lost in proliferating cells due to cell division. Therefore, in the second part of the thesis, in cooperation with Claudia Hagedorn and Hans J. Lipps (University Witten/Herdecke) an AAV vector genome was equipped with an autonomous replication element (Scaffold/matrix attachment region (S/MAR)). AAV-S/MAR encoding for eGFP and a blasticidin resistance gene and a control vector with the same TEC but lacking the S/MAR element (AAV-ΔS/MAR) were produced and transduced into highly proliferative HeLa cells. Antibiotic pressure was employed to select for cells stably maintaining the vector genome. AAV-S/MAR transduced cells yielded a higher number of colonies than AAV-ΔS/MAR-transduced cells. Colonies derived from each vector transduction were picked and cultured further. They remained eGFP-positive (up to 70 days, maximum cultivation period) even in the absence of antibiotic selection pressure. Interestingly, the mitotic stability of both AAV-S/MAR and control vector AAV-ΔS/MAR was found to be a result of episomal maintenance of the vector genome. This finding indicates that, under specific conditions such as the mild selection pressure we employed, “common” AAV vectors persist episomally. Thus, the S/MAR element increases the establishment frequency of stable episomes, but is not a prerequisite.

La cultura y el liderazgo en la estrategia de crecimiento por exportaciones del modelo de desarrollo japonés (1960-1980)

Normalmente el desarrollo de un país se ha explicado desde una perspectiva tradicional en términos de su crecimiento económico, teniendo en cuenta indicadores macroeconómicos como el PIB, la inflación y el desempleo. Poca atención se le ha puesto a la importancia que para el desarrollo de un país representan el capital humano y el proceso de liderazgo. Debido a lo anterior, mediante este estudio de caso, se pretende entender el éxito de la estrategia de crecimiento por exportaciones de Japón entre los años 1960-1980 teniendo en cuenta estos aspectos. Así, se busca sustentar que la incorporación de un tipo de liderazgo transformacional- transaccional y los elementos propios de su cultura como el confucianismo y el budismo, le imprimieron una perspectiva no economicista al éxito del modelo de desarrollo como parte de la triada empresa-estado-universidad. Lo anterior se realizará partiendo de un análisis cualitativo y con un enfoque en la economía política internacional y en el liderazgo. Este último estudiado desde las disciplinas de la administración, la sociología y la psicología

Tectonic evolution of Variscan Iberia: Gondwana–Laurussia

An integrated interpretation of the late Paleozoic structural and geochronological record of the Iberian Massif is presented and discussed under the perspective of a Gondwana-Laurussia collision giving way to the Variscan orogen. Compressional and extensional structures developed during the building of the Variscan orogenic crust of Iberia are linked together into major tectonic events operating at lithosphere scale. A review of the tectonometamorphic and magmatic evolution of the IberianMassif reveals backs and forths in the overall conver- gence between Gondwana and Laurussia during theamalgamation of Pangea in late Paleozoic times. Stages dom- inated by lithosphere compression are characterized by subduction, both oceanic and continental, development of magmatic arcs, (over- and under-) thrusting of continental lithosphere, and folding. Variscan convergence re- sulted in the eventual transference of a large allochthonous set of peri-Gondwanan terranes, the Iberian Allochthon, onto the Gondwana mainland. The Iberian Allochthon bears the imprint of previous interaction be- tween Gondwana and Laurussia, including their juxtaposition after the closure of the Rheic Ocean in Lower De- vonian times. Stages governed by lithosphere extension are featured by the opening of two short-lived oceanic basins that dissected previous Variscan orogenic crust, first in the Lower-Middle Devonian, following the closure of the Rheic Ocean, and then in the early Carboniferous, following the emplacement of the peri-Gondwanan allochthon. An additional, major intra-orogenic extensional event in the early-middle Carboniferous dismem- bered the Iberian Allochthon into individual thrust stacks separated by extensional faults and domes. Lateral tec- tonics played an important role through the Variscan orogenesis, especially during the creation of new tectonic blocks separated by intracontinental strike-slip shear zones in the late stages of continental convergence.

Social competence and emotional comprehension: How are they related in children?

The developmental progression of emotional competence in childhood provides a robust evidence for its relation to social competence and important adjustment outcomes. This study aimed to analyze how this association is established in middle childhood. For this purpose, we tested 182 Portuguese children aged between 8 and 11 years, of 3rd and 4th grades, in public schools. Firstly, for assessing social competence we used an instrument directed to children using critical social situations within the relationships with peers in the school context - Socially in Action-Peers (SAp) (Rocha, Candeias & Lopes da Silva, 2012); children were assessed by three sources: themselves, their peers and their teacher. Secondly, we assessed children’s emotional understanding, individually, with the Test of Emotion Comprehension (Pons & Harris, 2002; Pons, Harris & Rosnay, 2004). Relations between social competence levels (in a composite score and using self, peers and teachers’ scores) and emotional comprehension components (comprehension of the recognition of emotions, based on facial expressions; external emotional causes; contribute of desire to emotion; emotions based on belief; memory influence under emotional state evaluation; possibility of emotional regulation; possibility of hiding an emotional state; having mixed emotions; contribution of morality to emotion experience) were investigated by means of two SSA (Similarity Structure Analysis) - a Multidimensional Scaling procedure and the external variable as points technique. In the first structural analysis (SSA) we will consider self, peers and teachers’ scores on Social Competence as content variables and TEC as external variable; in the second SSA we will consider TEC components as content variables and Social Competence in their different levels as external variable. The implications of these MDS procedures in order to better understand how social competence and emotional comprehension are related in children is discussed, as well as the repercussions of these findings for social competence and emotional understanding assessment and intervention in childhood is examined.

Test of Emotion Comprehension: Exploring the underlying structure through Confirmatory Factor Analysis and Similarity Structure Analysis

Some decades of research on emotional development have underlined the contribution of several domains to emotional understanding in childhood. Based on this research, Pons and colleagues (Pons & Harris, 2002; Pons, Harris & Rosnay, 2004) have proposed the Test of Emotion Comprehension (TEC) which assesses nine domains of emotional understanding, namely the recognition of emotions, based on facial expressions; the comprehension of external emotional causes; impact of desire on emotions; emotions based on beliefs; memory influence on emotions; possibility of emotional regulation; possibility of hiding an emotional state; having mixed emotions; contribution of morality to emotional experiences. This instrument was administered individually to 182 Portuguese children aged between 8 and 11 years, of 3rd and 4th grades, in public schools. Additionally, we used the Socially in Action-Peers (SAp) (Rocha, Candeias & Lopes da Silva, 2012) to assess TEC’s criterion-related validity. Mean differences results in TEC by gender and by socio-economic status (SES) were analyzed. The results of the TEC’s psychometric analysis were performed in terms of items’ sensitivity and reliability (stability, test-retest). Finally, in order to explore the theoretical structure underlying TEC a Confirmatory Factor Analysis and a Similarity Structure Analysis were computed. Implications of these findings for emotional understanding assessment and intervention in childhood are discussed.

Efficacy of fungicides for the control of Fusarium head blight in wheat: cooperative trials results - 2014 crop season.

2016

Geographic distribution of ryegrass resistent to the clethodim herbicide in Rio Grande do Sul.

2016