Evaluación de un modelo didáctico analógico para el aprendizaje de energía interna y temperatura

Las dificultades de los estudiantes para conceptualizar correctamente las leyes de la termodinámica han sido estudiadas por diferentes autores, asimismo se han detectado los errores en nociones relativas a las magnitudes involucradas. Esas dificultades parecen residir en la falta de correspondencia entre el modelo macroscópico de las leyes de la termodinámica y el modelo cinético molecular de la materia. Ambos modelos teoréticos, uno macroscópico y otro microscópico se plantean habitualmente en la clase, de modo que esta falta de conexión sería en parte proveniente de la instrucción. Consideramos que existe una continuidad entre los modelos conceptuales de los alumnos y el modelo teorético objeto del aprendizaje. En este trabajo se propone un modelo didáctico analógico para la enseñanza de los conceptos de temperatura y energía interna y se evalúa su eficiencia. Los resultados obtenidos fueron positivos mostrando una mejor utilización del modelo cinético molecular por parte de los alumnos.Palabras Clave: aprendizaje activo; estrategias de enseñanza; energía interna y temperatura; modelos.Evaluation of an analogical didactic model for the learning of internal energy and temperatureThe difficulties to correctly conceptualize thermodynamics laws have alredy been studied by different authors. Errors in notions related to the magnitudes involved have been detected. It seems that these difficulties occur due to the lack of correspondences between the microscopic model from the thermodynamics laws and the molecular kinetic model. Both theoretic models, one of then macroscopic and the other microscopic are usually discussed en class, therefore, this lack of connection would parthy come from instruction. We believe that there is a continuity betwen the conceptual model and the theoretic model to be learnt. We propose an analogical didactic model applied to establish a difference betwen the concepts of internal energy and temperature and its efficiency is evaluated. The results obtained were positive showing a better one utilizacion of the molecular kinetic model on the part of the students.Key Words: classroom active learning; internal energy and temperature; models; strategies for teaching

La transferencia epistemológica de un modelo didáctico analógico

La línea de investigación sobre los procesos de enseñanza y aprendizaje científico basada en modelos analógicos ha adquirido relevancia en los últimos años, pero notamos que son pocos los trabajos que presentan aplicaciones en el aula para el nivel medio de enseñanza. Basándonos en el concepto de perfil epistemológico que propone Bachelard, hemos ahondado en la idea de modelo al objeto de extraer nuevas conclusiones que nos permitan no sólo redefinirla, sino también evaluar la transposición que resulta de su aplicación. En este trabajo presentamos una propuesta que permita medir la transposición didáctica que es alcanzada por la aplicación de modelos didácticos analógicos en el aula de ciencias, a la cual denominamos: transferencia epistemológica. Así, la transferencia epistemológica de un modelo didáctico analógico nos brinda una medida del perfil epistemológico que es alcanzado con su aplicación en el aula de ciencias.Palabras claves: transferencia epistemológica; perfil epistemológico; modelos; modelos didácticos analógicos.The epistemological transfer of an analogical didactic modelResearch on scientific teaching and learning processes based on analogical models has acquired a great deal of importance in the last years. However, we have realized that there are just a few papers that introduce their use in secondary school classrooms. Based on the concepts of epistemological profile proposed by Bachelard, we have dug deeply into the idea of “model”. We arrived at new conclusions that allow us not only to redefine it, but also to evaluate the transposition that comes up from its application. In this paper we introduce a proposal that allows us to measure the didactic transposition reached under the application of analogical didactic models in the science classrooms which we name epistemological transfer. Therefore, the epistemological transfer of an analogical didactic model, provides us with the degree of the epistemological profile reached under its application in science classrooms.Key words: epistemological transfer; epistemological profile; models; analogical didactic models

Aprendizaje de los conceptos de masa, peso y gravedad. Investigación de la efectividad de un modelo analógico

La línea de investigación sobre los procesos de enseñanza y aprendizaje científico basada en modelos analógicos ha adquirido relevancia, pero notamos que son pocas las aplicaciones en el aula, sobre todo en el nivel medio de enseñanza. Los modelos didácticos analógicos son una herramienta importante para la instrucción pero a condición de que el profesor y los alumnos adquieran una visión en común sobre el análogo y se describan sus limitaciones comparado con el modelo teorético. Se espera del alumno una toma de conciencia sobre sus procesos y eventos cognitivos para que pueda evaluar los progresos y resultados, comprendiendo su propia versión acerca de la naturaleza de su conocimiento y sobre el proceso de aprendizaje, es decir sobre sus esencias epistemológicas. En este trabajo se evalúa la eficiencia de un modelo didáctico analógico para la enseñanza de los conceptos de masa, peso y gravedad mediante un estudio correlacional, cuasiexperimental con posprueba y grupo control.Palabras claves: aprendizaje activo; estrategias de enseñanza; masa, peso y gravedad. Modelos analógicos.Learning the concepts of mass, weight and gravity. Investigation of the effectiveness of an analog modelThe line of investigation on the processes of education and scientific learning based on analogical models has acquired relevance, but we noticed that the applications in the classroom are few, mainly in the middle level of education. The analogical didactic models are an important tool for instruction provided that the teacher and the pupils acquire a shared vision on the analogies and their described limitations compared with the theoretical model. The learner is expected to be aware of his mental processes and cognitive operations, so that he can evaluate his own progress, including an understanding of his own learning process, that is to say, of his epistemological essences. In this work the efficiency of an analogical didactic model for the teaching of the mass, weight and gravity concepts is evaluated by means of a correlation quasi-experimental study, with postest and group control.Key words: active learning; teaching strategies; mass; weight and gravity; analogical models

Stakeholder narratives on trypanosomiasis, their effect on policy and the scope for One Health

Background This paper explores the framings of trypanosomiasis, a widespread and potentially fatal zoonotic disease transmitted by tsetse flies (Glossina species) affecting both humans and livestock. This is a country case study focusing on the political economy of knowledge in Zambia. It is a pertinent time to examine this issue as human population growth and other factors have led to migration into tsetse-inhabited areas with little historical influence from livestock. Disease transmission in new human-wildlife interfaces such as these is a greater risk, and opinions on the best way to manage this are deeply divided. Methods A qualitative case study method was used to examine the narratives on trypanosomiasis in the Zambian policy context through a series of key informant interviews. Interviewees included key actors from international organisations, research organisations and local activists from a variety of perspectives acknowledging the need to explore the relationships between the human, animal and environmental sectors. Principal Findings Diverse framings are held by key actors looking from, variously, the perspectives of wildlife and environmental protection, agricultural development, poverty alleviation, and veterinary and public health. From these viewpoints, four narratives about trypanosomiasis policy were identified, focused around four different beliefs: that trypanosomiasis is protecting the environment, is causing poverty, is not a major problem, and finally, that it is a Zambian rather than international issue to contend with. Within these narratives there are also conflicting views on the best control methods to use and different reasoning behind the pathways of response. These are based on apparently incompatible priorities of people, land, animals, the economy and the environment. The extent to which a One Health approach has been embraced and the potential usefulness of this as a way of reconciling the aims of these framings and narratives is considered throughout the paper. Conclusions/Significance While there has historically been a lack of One Health working in this context, the complex, interacting factors that impact the disease show the need for cross-sector, interdisciplinary decision making to stop rival narratives leading to competing actions. Additional recommendations include implementing: surveillance to assess under-reporting of disease and consequential under-estimation of disease risk; evidence-based decision making; increased and structurally managed funding across countries; and focus on interactions between disease drivers, disease incidence at the community level, and poverty and equity impacts

Structural Probe of a Glass Forming Liquid: Generalized Compressibility

We introduce a new quantity to probe the glass transition. This quantity is a linear generalized compressibility which depends solely on the positions of the particles. We have performed a molecular dynamics simulation on a glass forming liquid consisting of a two component mixture of soft spheres in three dimensions. As the temperature is lowered (or as the density is increased), the generalized compressibility drops sharply at the glass transition, with the drop becoming more and more abrupt as the measurement time increases. At our longest measurement times, the drop occurs approximately at the mode coupling temperature $T_C$. The drop in the linear generalized compressibility occurs at the same temperature as the peak in the specific heat. By examining the inherent structure energy as a function of temperature, we find that our results are consistent with the kinetic view of the glass transition in which the system falls out of equilibrium. We find no size dependence and no evidence for a second order phase transition though this does not exclude the possibility of a phase transition below the observed glass transition temperature. We discuss the relation between the linear generalized compressibility and the ordinary isothermal compressibility as well as the static structure factor.Comment: 18 pages, Latex, 26 encapsulated postscript figures, revised paper is shorter, to appear in Phys. Rev.

Resonant nonstationary amplification of polychromatic laser pulses and conical emission in an optically dense ensemble of neon metastable atoms

Experimental and numerical investigation of single-beam and pump-probe interaction with a resonantly absorbing dense extended medium under strong and weak field-matter coupling is presented. Significant probe beam amplification and conical emission were observed. Under relatively weak pumping and high medium density, when the condition of strong coupling between field and resonant matter is fulfilled, the probe amplification spectrum has a form of spectral doublet. Stronger pumping leads to the appearance of a single peak of the probe beam amplification at the transition frequency. The greater probe intensity results in an asymmetrical transmission spectrum with amplification at the blue wing of the absorption line and attenuation at the red one. Under high medium density, a broad band of amplification appears. Theoretical model is based on the solution of the Maxwell-Bloch equations for a two-level system. Different types of probe transmission spectra obtained are attributed to complex dynamics of a coherent medium response to broadband polychromatic radiation of a multimode dye laser.Comment: 9 pages, 13 figures, corrected, Fig.8 was changed, to be published in Phys. Rev.

Symmetry-breaking Effects for Polariton Condensates in Double-Well Potentials

We study the existence, stability, and dynamics of symmetric and anti-symmetric states of quasi-one-dimensional polariton condensates in double-well potentials, in the presence of nonresonant pumping and nonlinear damping. Some prototypical features of the system, such as the bifurcation of asymmetric solutions, are similar to the Hamiltonian analog of the double-well system considered in the realm of atomic condensates. Nevertheless, there are also some nontrivial differences including, e.g., the unstable nature of both the parent and the daughter branch emerging in the relevant pitchfork bifurcation for slightly larger values of atom numbers. Another interesting feature that does not appear in the atomic condensate case is that the bifurcation for attractive interactions is slightly sub-critical instead of supercritical. These conclusions of the bifurcation analysis are corroborated by direct numerical simulations examining the dynamics of the system in the unstable regime.MICINN (Spain) project FIS2008- 0484

The First VERITAS Telescope

The first atmospheric Cherenkov telescope of VERITAS (the Very Energetic Radiation Imaging Telescope Array System) has been in operation since February 2005. We present here a technical description of the instrument and a summary of its performance. The calibration methods are described, along with the results of Monte Carlo simulations of the telescope and comparisons between real and simulated data. The analysis of TeV $\gamma$-ray observations of the Crab Nebula, including the reconstructed energy spectrum, is shown to give results consistent with earlier measurements. The telescope is operating as expected and has met or exceeded all design specifications.Comment: Accepted by Astroparticle Physic

Temporal fluctuations of waves in weakly nonlinear disordered media

We consider the multiple scattering of a scalar wave in a disordered medium with a weak nonlinearity of Kerr type. The perturbation theory, developed to calculate the temporal autocorrelation function of scattered wave, fails at short correlation times. A self-consistent calculation shows that for nonlinearities exceeding a certain threshold value, the multiple-scattering speckle pattern becomes unstable and exhibits spontaneous fluctuations even in the absence of scatterer motion. The instability is due to a distributed feedback in the system "coherent wave + nonlinear disordered medium". The feedback is provided by the multiple scattering. The development of instability is independent of the sign of nonlinearity.Comment: RevTeX, 15 pages (including 5 figures), accepted for publication in Phys. Rev.