Particle Acceleration and Intermittent Turbulence in Coronal Loops

A test particle numerical experiment is performed to simulate particle acceleration in low-frequency turbulence generated by footpoint motions in a coronal loop. The turbulence is modeled within the reduced MHD theory. Only the effect of the resistive electric field E|| is retained, which is mainly parallel to the axial magnetic field. In its spectrum, the contribution of small scales is dominant. The spatial structure of E|| is obtained by a synthetic turbulence method (p-model), which allows us to reproduce intermittency. By solving the relativistic motion equations, the time evolution of particle distribution is calculated. Electrons can be accelerated to energies of the order of 50 keV in less than 0.3 s, and the final energy distribution can exhibit a power-law range. A correlation is found between the heating events in the MHD turbulence and particle acceleration that is qualitatively similar to what is observed in solar flares. Spatial intermittency plays a key role in acceleration, enhancing both the extension of a power-law range and the maximum energy

El rebote de las esferas según los profesores de primaria : un acercamiento a las ideas en Física y a las representaciones epistemológicas a través de una formación para la construcción de problemas científicos

Los currículos de Francia y Colombia presentan algunos puntos de referencia comunes relacionados con la enseñanza de las ciencias en la educación básica. Se trata de privilegiar la formulación de problemas como punto de partida para el aprendizaje dentro de las prácticas experimentales.La enseñanza basada en la indagación se establece como principio motivador de estas disposiciones, sin embargo, de acuerdo a algunos investigadores, los profesores no las asimilan correctamente. El objetivo de esta investigación es la formación para la construcción de problemas que permitan aprofesores «no-científicos» la construcción de conocimientos. En esta comunicación presentamos una primera aproximación referente al rebote de las esferas como tema a desarrollar en física y a las posturas de estos profesores frente a la construcción de un problema «fecundo»

El rebote de las esferas según los profesores de primaria : un acercamiento a las ideas en Física y a las representaciones epistemológicas a través de una formación para la construcción de problemas científicos

Los currículos de Francia y Colombia presentan algunos puntos de referencia comunes relacionados con la enseñanza de las ciencias en la educación básica. Se trata de privilegiar la formulación de problemas como punto de partida para el aprendizaje dentro de las prácticas experimentales.La enseñanza basada en la indagación se establece como principio motivador de estas disposiciones, sin embargo, de acuerdo a algunos investigadores, los profesores no las asimilan correctamente. El objetivo de esta investigación es la formación para la construcción de problemas que permitan aprofesores «no-científicos» la construcción de conocimientos. En esta comunicación presentamos una primera aproximación referente al rebote de las esferas como tema a desarrollar en física y a las posturas de estos profesores frente a la construcción de un problema «fecundo»

L’usage des exemples dans l’enseignement de la physique à l’université : un marqueur de l’identité pédagogique des enseignants-chercheurs ?

L’usage des exemples dans l’enseignement de la physique à l’université apparaît comme une pratique aussi banale qu’incontournable. C’est à cette pratique que nous nous intéressons ici. En tant que chercheurs en didactique de la physique, nous nous intéressons à ce que des enseignants-physiciens disent lorsqu’ils décrivent quand, comment et pourquoi ils utilisent des exemples lorsqu’ils enseignent. Ces usages déclarés sont considérés comme révélateurs du rapport que les enseignants-chercheurs entretiennent avec l’enseignement et l’apprentissage de la physique ; ils nous permettent de remonter à certaines dimensions de leur identité professionnelle, considérée dans ses dimensions épistémologiques et pédagogiques.Using examples in physics teaching at university level is commonplace and inevitable. As researchers in physics education (didactic of physics) we question what academics in physics say when they describe why, when and how they use examples while they teach. These declared uses are considered as markers of the relationships academics maintain with the teaching and the learning of the physics; they allow us to go back to certain dimensions of their professional identity, considered in its epistemological and educational dimensions

Concept and critique: Two intertwined routes for intellectual development in scienceref: Viennot, L. & Décamp, N. 2018. Concept and critique: Two intertwined routes for intellectual development in science. In Complementary and Converging Perspectives on Conceptual Change, T. Amin and O. Levrini, New York: Routledge, 190-197

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Co-development of Conceptual Understanding and Critical Attitude: Analyzing texts on radiocarbon dating

International audienceThis research documents the impact of a teaching interview aimed at developing a critical attitude in students, and focused on a particular topic: radiocarbon dating. This teaching interview is designed to have students react to limited written explanations of the phenomenon under study, and to express their possible frustration or intellectual satisfaction in relation to these texts. We aim to document the possible link between students' developing conceptual understanding of a topic and their ability to express their frustration when presented with very incomplete explanations, or their intellectual satisfaction when presented with complete explanation. As a side product we intend to observe some of their a priori ideas concerning this topic. Ten teaching interviews conducted with fourth-year university students were recorded, transcribed and coded. Beyond a series of results concerning students' a priori understanding of the domain, the analysis of the interviews suggests that, when students are presented with texts of increasing completeness and discuss these with the interviewer, their critical reactions evolve in time in a very specific way. We propose a tentative model for this co-evolution of student conceptual command and critical stance. The discussion bears on possible interpretations for the " anesthesia of judgment " observed in most students at the beginning of the interview, and for a few of them throughout the discussion. Keeping in mind the " competence vs concepts " current alternative, the conditions that seem to free students' critical potential are analysed in relation to their evolving command of the topic and their degree of intellectual satisfaction

Critiquing Explanations in Physics: Obstacles and Pedagogical Decisions Among Beginning Teachers

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Conceptual and critical development in student teachers: first steps towards an integrated comprehension of osmosis

International audienceIn a context of strong valuation of competences in physics teaching, students' critical thinking is widely advocated but there is also a risk that conceptual structuring be disregarded. For that reason, this investigation is focused on possible links between the development of critical attitude and conceptual understanding. We analyzed in detail how conceptual comprehension and critical attitude develop when a person confronts various explanations of a nonobvious topic. To this end, we conducted a fine grained analysis of five prospective teachers' critical and conceptual development during a one hour and a half interaction with an expert. This investigation completes a series of three previous studies addressing the same general research question in respect of three different physics topics. In this instance, the focus is on the topic of osmosis. A content analysis led us to identify some lines of reasoning that we expected to observe as well as conceptual targets for the interviews. In line with an integrative perspective, these conceptual goals provide some opportunities to link osmosis phenomena with a molecular approach. The transcripts were processed following two lines of analysis, one conceptual and the other focusing on critical attitude as well as metacognitive and affective affects. The findings confirm the significant occurrence of the expected lines of reasoning. They also suggest that students need to reach a threshold of comprehension, beyond logical necessity, before expressing critiques toward inaccurate texts or their previous views (" delayed critique "). Students' questions about the meanings of current phrases relating to pressure in liquids are shown to play a decisive role to activate their potential of critique as well as significant conceptual steps forward. In discussing our results, we explain how this study contributes to a holistic picture of student teachers' conceptual and critical co-development when interacting with an expert. The prevalence of " delayed critiques " aligns with our previous results. Additionally, a more specific finding of this study is the precise localization of events that are likely to trigger rapid conceptual and critical evolution. A discussion about further research and perspectives concerning the teaching of osmosis and students' formation to critique ends the paper

Codevelopment of conceptual understanding and critical attitude: toward a systemic analysis of the survival blanket

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