Escuela de ayudantes alumnos: arte y parte del ayudante alumno como tutor de pares

La preocupación por cómo y para qué enseñar y aprender se muestra como una constante a lo largo del tiempo; ello invita a plantear alternativas innovadoras. Las experiencias en Escuelas de Ayudantes resultan alentadoras en capacitación docente; inserción en equipos docentes; mejoramiento en la formación de grado; integración transversal y vertical; reflexión crítica; apropiación de conocimientos; etc. Dentro del contexto de las “prácticas de docencia compartida”, precisamente le cabe a los alumnos compartir los procesos de aprendizaje entre ellos y los docentes. Objetivo: implementar un sistema de Tutorías de Pares en Histología en las dimensiones pedagógica y disciplinar. Participan del trabajo: docentes, no docente, asesora pedagógica y alumnos. Se preveen actividades áulicas y de Formación y Capacitación Pedagógica y Científica. Se aspira a estimular el pensamiento reflexivo entre el contenido teórico y la práctica profesional; generar un espacio de discusión y formulación de propuestas orientadas al mejoramiento del aprendizaje, propiciar el desarrollo de habilidades; capacitar al aspirante en actividades de docencia; ofrecer un ámbito para el desarrollo de actividades de investigación propiamente dichas y como saber científico aplicado a la docencia de grado; fomentar la habilidad para desempeñar tareas en equipo; favorecer la formación de recursos humanos desde el grado; abordar la problemática de deserción estudiantil. PIIMEG SECyTUNRC( 2011-2012).Eje temático 2: Los cambios e innovaciones en los procesos de formación a - Alternativas didácticas y experiencias de renovación de la enseñanzaFacultad de Ciencias Agrarias y Forestale

Determination of the structural phase and octahedral rotation angle in halide perovskites

A key to the unique combination of electronic and optical properties in halide perovskite materials lies in their rich structural complexity. However, their radiation sensitive nature limits nanoscale structural characterization requiring dose efficient microscopic techniques in order to determine their structures precisely. In this work, we determine the space-group and directly image the Br halide sites of CsPbBr3, a promising material for optoelectronic applications. Based on the symmetry of high-order Laue zone reflections of convergent-beam electron diffraction, we identify the tetragonal (I4/mcm) structural phase of CsPbBr3 at cryogenic temperature. Electron ptychography provides a highly sensitive phase contrast measurement of the halide positions under low electron-dose conditions, enabling imaging of the elongated Br sites originating from the out-of-phase octahedral rotation viewed along the [001] direction of I4/mcm persisting at room temperature. The measurement of these features and comparison with simulations yield an octahedral rotation angle of 6.5°(±1.5°). The approach demonstrated here opens up opportunities for understanding the atomic scale structural phenomena applying advanced characterization tools on a wide range of radiation sensitive halide-based all-inorganic and hybrid organic-inorganic perovskites

An analytical model of nonproportional scintillator light yield in terms of recombination rates

Analytical expressions for the local light yield as a function of the local deposited energy (-dE/dx) and total scintillation yield integrated over the track of an electron of initial energy E are derived from radiative and/or nonradiative rates of first through third order in density of electronic excitations. The model is formulated in terms of rate constants, some of which can be determined independently from time-resolved spectroscopy and others estimated from measured light yield efficiency as a constraint assumed to apply in each kinetic order. The rates and parameters are used in the theory to calculate scintillation yield versus primary electron energy for comparison to published experimental results on four scintillators. Influence of the track radius on the yield is also discussed. Results are found to be qualitatively consistent with the observed scintillation light yield. The theory can be applied to any scintillator if the rates of the radiative and nonradiative processes are known

Luminescence and ultraviolet excitation spectroscopy of SrI2I_2 and SrI2I_2:Eu2+Eu^2+

We report measurements of luminescence and its ultraviolet excitation spectra in SrI2 and SrI2:Eu2+ at temperatures of 10 and 300 K. Attention is focused on determining the exciton energy and its temperature shift from features of the excitation spectra and limits placed by absorption spectroscopy on a 120 μm thin crystal, on observation of a broadened Eu emission band attributed to trace Eu associated with oxygen in nominally undoped crystals, and on adding observations concerning the 3.4 eV band at low temperature attributed by Pustovarov et al. to the self-trapped exciton