Investigación de algunos indicadores del estatus cognitivo de las concepciones sobre el estado eléctrico

Tomando como hipótesis de trabajo la suposición de que las concepciones alternativas de los alumnos tienen una naturaleza implícita y un carácter probabilístico y difuso, se han estudiado algunos indicadores del estatus de las concepciones sobre el estado eléctrico. La investigación de las dimensiones: estabilidad en el tiempo, sin mediar enseñanza, coherencia lógica, plausibilidad y coexistencia, ha permitido establecer comparaciones cognitivas entre la acepción académica y las ideas previas. También se ha logrado establecer diferencias internas entre estas últimas, a fin de esclarecer el tipo de dificultad que representan para la evolución conceptual. El estudio empírico se realizó con 52 estudiantes de Magisterio.Assuming the hypothesis that students' alternative conceptions have an implicit nature, and probabilistic and indeterminate features, some indicators of cognitive status of these explanations about the notion of electric state have been investigated. Research into the dimensions: stability over a period of time without teaching, coexistence, logic consistency, and plausibility, has produced comparisons between the different explanations. Several conclusions about the differences between the conceptions have been derived, with the aim of considering the sort of difficulties that there may be for a satisfactory conceptual evolution. The sample for the empirical research included 52 science students of a primary teacher training college

Enfoque CTS en la enseñanza de la energía nuclear : análisis de su tratamiento en textos de física y química de la ESO

En este artículo se muestran los resultados y las conclusiones de un estudio exploratorio sobre el enfoque ciencia-tecnología-sociedad (CTS), introducido en la enseñanza de la energía nuclear en Secundaria. Para ello, se analizan once libros de texto de las editoriales más utilizadas en la enseñanza de la física y química de 3º de Educación Secundaria Obligatoria (ESO), en la Comunidad Autónoma de Andalucía (España).In this paper, we present the results and conclusions of an exploratory study on Science-Technology-Society (STS) approach, introduced in teaching of nuclear power in Secondary School. We analyse eleven textbooks of the most used publisher in physics and chemistry teaching in Secondary School (14-15 years-old), in region of Andalusia (Spain)

Enseñanza de la energía en la etapa 6-12 años : un planteamiento desde el ámbito curricular de las máquinas

El artículo plantea la enseñanza de la energía en la etapa de primaria a partir del ámbito curricular de las máquinas. Tras una revisión de la literatura, se proponen, a modo de hipótesis, tres niveles para la introducción progresiva de diversos conceptos relacionados con la energía en las máquinas. Asimismo, se destaca la contribución del planteamiento didáctico al desarrollo de la competencia científica, en sintonía con lo sugerido actualmente para los niveles educativos básicos. Se finaliza con una propuesta didáctica concreta, en el marco de una investigación escolar, para abordar en el aula algunos aspectos relacionados con la energía en las máquinas.This paper proposes a method for teaching energy in primary school based on machines from the science curriculum. A literature review on the different approaches to teaching energy and students' associated learning difficulties are presented. A hypothesis is presented consisting of three levels for progressive introduction of the concepts. This is followed by a discussion on the application for the development of students' scientific competencies. Emphasis is placed on the suggested learning outcomes for each education level. Lastly, a didactic classroom activity is presented in the context of inquiry-based learning to develop students conceptual understandings related to energy and machines

Física de semiconductores en la enseñanza básica de la electrónica: primeros pasos de un proceso de transposición didáctica

El artículo plantea, como innovación didáctica, la introducción de nociones de física de semiconductores (FS) en Educación Secundaria Obligatoria (ESO). Se pretende así que los alumnos de la etapa adquieran un conocimiento básico del fundamento físico de los dispositivos electrónicos. Bajo la hipótesis general de que es posible integrar nociones de FS en clases de física y química de la ESO (14-16 años), se establecen una serie de hipótesis específicas, que guían dicha integración. Éstas implican la necesidad de conocer las ideas y obstáculos de aprendizaje más frecuentes de alumnos de la etapa, en relación con el tópico, a fin de identificar la demanda de aprendizaje. A continuación, se propone una transposición didáctica del tópico para el nivel de ESO, en la que se establecen: los contenidos del actual currículo, que sirven de «puente» entre lo que el alumno ya sabe con lo que va a aprender; y el tratamiento didáctico de los contenidos propuestos, junto con los objetivos de aprendizaje.This article proposes, as an educational innovation, the introduction of notions of semiconductor physics in the Compulsory Secondary Education, so that students at this stage may acquire a basic knowledge of the physical foundations of electronics. Under the general hypothesis that it is possible to integrate some of these basic notions on the topic into the physics and chemistry class, a series of specific hypotheses that guide the integration are established. These imply the need to knowing the students' most frequents ideas and learning obstacles regarding the topic, in order to identify the learning demand. Then, a didactic transposition of the semiconductor physics to the said educational stage is proposed, indicating (a) the contents of physics and chemistry curriculum that serve as bridge between the knowledge that the students already have and what they are going to learn, and (b) the didactic treatment of the new contents along with the learning objects

Alfabetización científica en la etapa 3-6 años: un análisis de la regulación estatal de enseñanzas mínimas

S'analitza l'alfabetització científica promoguda per la regulació d'ensenyaments mínims per a l'etapa 3-6 anys a Espanya. Per a això, es va dissenyar i aplicar un qüestionari combinant processos d'anàlisi inter-i intra-jutges com a estratègia de validació i fiabilitat. Es va valorar com el document atén les dimensions, relatives a la ciència escolar: construcció de la ciència escolar; axiologia i psicologia de l'aprenentatge de la ciència; objectius i competències; continguts; activitats, disseny i estratègies d'ensenyament; recursos didàctics, i avaluació. Els resultats indiquen que la ciència escolar suggerida en el document no sintonitza, en una part important, amb les tendències actuals de la Didàctica de les Ciències. A conseqüència de les mancances detectades, es fan algunes recomanacions que millorarien la proposta oficial.An analysis is made of the scientific literacy promoted by Spain’s national curriculum for the 3-6 year old stage. To this end, a questionnaire was designed and implemented combining inter- and intra-rater processes of analysis as a strategy of validation and reliability. An evaluation was made of how the official document addresses the following dimensions of science education at this stage: the construction of school science; the axiology and psychology of learning science; objectives and competences; content; teaching activities, design, and strategies; and teaching resources and evaluation. The results indicate that the school science actually being put forward in the document is, to a major degree, out of tune with current trends in Science Teaching. In view of the deficiencies identified in the document several improvements are recommended.Se analiza la alfabetización científica promovida por la regulación de las enseñanzas mínimas para la etapa 3-6 años en España. Para ello, se diseñó y aplicó un cuestionario combinando procesos de análisis inter-e intra-jueces como estrategia de validación y fiabilidad. Se valoró como el documento atiende las dimensiones relativas a la ciencia escolar: construcción de la ciencia escolar; axiología y psicología del aprendizaje de la ciencia; objetivos y competencias; contenidos; actividades, diseño y estrategias de enseñanza; recursos didácticos, y evaluación. Los resultados indican que la ciencia escolar sugerida en el documento no sintoniza, en una parte importante, con las tendencias actuales de la Didáctica de las Ciencias. A consecuencia de las carencias detectadas, se hacen algunas recomendaciones que mejorarían la propuesta oficial

¿Qué educación científica se promueve para la etapa de primaria en España? : Un análisis de las prescripciones oficiales de la LOE

Se analiza la educación científica promovida por el currículo oficial de primaria en España. El análisis centra la atención en los aspectos siguientes relativos a la ciencia escolar: naturaleza y sociología de la ciencia; axiología; psicología en el aprendizaje de la ciencia; objetivos, competencias, contenidos y criterios de evaluación; actividades, recursos y estrategias de enseñanza. Los resultados indican que las prescripciones del currículo oficial de la LOE para la educación científica en primaria no sintonizan adecuadamente con las actuales tendencias en Didáctica de las Ciencias. A la vista de las carencias detectadas, se hacen algunas recomendaciones que mejorarían la propuesta oficial al respecto.Science education promoted by the national curriculum of primary education in Spain is analyzed. The analysis pays attention to the following aspects regarding the school science: nature and sociology of science; axiology; psychology in science learning; goals, competences, contents and evaluation criteria; activities, didactic and methodological resources and teaching strategies. Results indicate that primary school science proposed in the national curriculum does not completely adjust with current trends in Science Education. In view of the lacks detected in the curriculum several recommendations are proposed

Bioinformatic analysis of outer membrane proteome of Neisseria meningitidis and Neisseria lactamica

Two-dimensional electrophoresis (isoelectric focusing/SDS-PAGE) and Western-blotting techniques were used to analyze and compare common and/or specific outer-membrane proteins and antigens from Neisseria meningitidis and Neisseria lactamica. Bioinformatic image analyses of proteome and immunoproteome maps indicated the presence of numerous proteins and several antigens shared by N. meningitidis and N. lactamica, although the inter-strain variation in the maps was of similar magnitude to the inter-species variation, and digital comparison of the maps did not reveal proteins found to be identical by MALDI-TOF fingerprinting analysis. PorA and RmpM, two relevant outer-membrane antigens, manifested as various spots at several different positions. While some of these were common to all the strains analyzed, others were exclusive to N. meningitidis and their electrophoretic mobilities were different than expected. One such spot, with a molecular mass of 19 kDa, may be the C-terminal fragment of RmpM (RmpM-Cter). The results demonstrate that computer-driven analysis based exclusively on spot positions in the proteome or immunoproteome maps is not a reliable approach to predict the identity of proteins or antigens; rather, other identification techniques are necessary to obtain accurate comparisons. [Int Microbiol 2007; 10(1):5-11

Customer functional value creation through a sustainable entrepreneurial orientation approach

This paper advances a theoretical model to empirically test firms’ behaviour regarding sustainable entrepreneurship, enhancing what researchers have recently proposed at a solely conceptual level; this entails sustainable entrepreneurship being understood as a discipline that reliably allows organizations to successfully respond to sustainable development and market requirements. The authors suggest an integrated approach of dynamic-capabilities, S-D logic and product-service system views, which highlights the managerial predisposition to adopt a strategic position that fosters value in use (instead of regular property value), according to the current school of thoughts engaged with innovation and sustainable development. In this regard, this paper investigates structural influences (direct and indirect) of sustainable entrepreneurial orientation and customer functional value creation in firm performance. Hypotheses are tested using the partial least squares method on a multisectoral sample of 210 companies randomly stratified with proportional allocation. The findings indicate that a sustainable entrepreneurial orientation not only has a positive and direct relationship with firm performance, but also that this relationship improves when it is mediated by customer functional value creation. Further research pathways are provided

Locus NMB0035 codes for a 47-kDa surface-accessible conserved antigen in Neisseria

A 47 kDa neisserial outer-membrane antigenic protein (P47) was purified to homogeneity and used to prepare polyclonal anti-P47 antisera. Protein P47 was identified by MALDI-TOF fingerprinting analysis as the hypothetical lipoprotein NMB0035. Two-dimensional diagonal SDS-PAGE results suggested that, contrary to previous findings, P47 is not strongly associated with other proteins in membrane complexes. Western blotting with the polyclonal monospecific serum showed that linear P47 epitopes were expressed in similar amounts in the 27 Neisseria meningitidis strains tested and, to a lesser extent, in commensal Neisseria, particularly N. lactamica. However, dot-blotting assays with the same serum demonstrated binding variability between meningococcal strains, indicating differences in surface accessibility or steric hindrance by other surface structures. Specific anti-P47 antibodies were bactericidal against the homologous strain but had variable activity against heterologous strains, consistent with the results from dot-blotting experiments. An in-depth study of P47 is necessary to evaluate its potential as a candidate for new vaccine designs. [Int Microbiol 2006; 9(4):273-280

Photoluminescence study of excitons in homoepitaxial GaN

High-resolution photoluminescence spectra have been measured in high-quality homoepitaxial GaN grown on a free-standing GaN substrate with lower residual strain than in previous work. Unusually strong and well-resolved excitonic lines were observed. Based on free- and bound exciton transitions some important GaN parameters are derived. The Arrhenius plot of the free A exciton recombination yields a binding energy of 24.7 meV. Based on this datum, an accurate value for the band-gap energy, EG(4.3 K) = 3.506 eV, can be given. From the donor bound excitons and their “two-electron” satellites, the exciton localization energy and donor ionization energy are deduced. Finally, estimates of the electron and hole masses have been obtained within the effective mass [email protected] ; [email protected]