Theoretical study of elastic electron scattering off stable and exotic nuclei

Results for elastic electron scattering by nuclei, calculated with charge densities of Skyrme forces and covariant effective Lagrangians that accurately describe nuclear ground states, are compared against experiment in stable isotopes. Dirac partial-wave calculations are performed with an adapted version of the ELSEPA package. Motivated by the fact that studies of electron scattering off exotic nuclei are intended in future facilities in the commissioned GSI and RIKEN upgrades, we survey the theoretical predictions from neutron-deficient to neutron-rich isotopes in the tin and calcium isotopic chains. The charge densities of a covariant interaction that describes the low-energy electromagnetic structure of the nucleon within the Lagrangian of the theory are used to this end. The study is restricted to medium and heavy mass nuclei because the charge densities are computed in mean field approach. Since the experimental analysis of scattering data commonly involves parameterized charge densities, as a surrogate exercise for the yet unexplored exotic nuclei, we fit our calculated mean field densities with Helm model distributions. This procedure turns out to be helpful to study the neutron-number variation of the scattering observables and allows us to identify correlations of potential interest among some of these observables within the isotopic chains.Comment: 18 pages, 14 figures, revtex4; modifications in text and figure

Electron supersurface scattering on polycrystalline Au

Supersurface electron scattering, i.e., electron energy losses and associated deflections in vacuum above the surface of a medium, is shown to contribute significantly to electron spectra. We have obtained experimental verification (in absolute units) of theoretical predictions that the angular distribution of the supersurface backscattering probability exhibits strong oscillations which are anticorrelated with the generalized Ramsauer-Townsend minima in the backscattering probability. We have investigated 500-eV electron backscattering from an Au surface for an incidence angle of 70° and scattering angles between 37° and 165°. After removing the contribution of supersurface scattering from the experimental data, the resulting angular and energy distribution agrees with the Landau-Goudsmit-Saunderson (LGS) theory, which was proposed about 60 years ago, while the raw data are anticorrelated with LGS theory. This result implies that supersurface scattering is an essential phenomenon for quantitative understanding of electron spectra

Aplicabilidad del Vídeo en el Método de Resolución de problemas en Fisioterapia

La presente tesis parte del propósito de analizar la forma óptima de presentar los casos clínicos en la docencia de Fisioterapia en el marco del Aprendizaje basado en problemas (ABP). En concreto, analizar las ventajas de presentar los casos mediante vídeo. Utiliza una metodología cualitativa y cuantitativa (estudio observacional de intervención; comparación de diferentes variables antes-después de las intervenciones realizadas) y se realiza en tres cursos consecutivos. Los sujetos de estudio son los alumnos matriculados en Fisioterapia el curso 2005‐06. Con estos alumnos, durante el primer curso, se realiza una experiencia de ABP con objeto de comparar los resultados de trabajar el caso en formato vídeo versus formato papel. En segundo curso, se aplica a la docencia en ABP la presentación de casos mediante vídeo y se comparan los estudiantes que han realizado esta experiencia con sus compañeros, que no la realizan. En tercero, se estudia si la visualización de repetidos vídeos redunda en una mejora de la capacidad de observación de los alumnos. Los resultados obtenidos permiten concluir que, en el contexto del ABP, la presentación de casos mediante vídeo consigue similitud con la práctica real en lo concerniente a la visualización de los pacientes, sin embargo, la imposibilidad de interactuar con ellos representa una importante limitación, especialmente para los alumnos de los últimos cursos. Así, favorece la comprensión, la retención del caso y la motivación de los alumnos. Se confirma que la visualización de repetidos vídeos revierte en una mejora de la capacidad de observación de los alumnos.The present thesis leaves from the intention to analyze the optimal form within the framework to present clinical cases in teaching of Physical Therapy of the Problems Based Learning (PBL). In particular, to analyze advantages to present the cases in video. It uses a qualitative and quantitative methodology (observational study of intervention; comparison of different variables before -after the made interventions) and is made in three consecutive courses. The study subjects are the students registered in Physical Therapy course 2005 ‐ 06. With these students, during the first course, an experience of PBL with object is made to compare the results of working the case in format video versus format paper. In second course, the presentation of cases by means of video is applied to teaching in ABP and the students compare themselves who have made this experience with their companions, who do not make it. In third, it studies if the visualization of repeated videos results in an improvement of students' capacity of observation. The obtained results allow concluding that, in the context of the PBL, the presentation of cases by means of video obtains similarity with the real practice as for the visualization of the patients; nevertheless, the impossibility to interact with them represents an important limitation, especially for the students of the last courses. Thus, it favors the understanding, the retention of the case and the motivation of the students. It is confirmed that the visualization of repeated videos reverts in an improvement of students' capacity of observation

Electron scattering in isotonic chains as a probe of the proton shell structure of unstable nuclei

Electron scattering on unstable nuclei is planned in future facilities of the GSI and RIKEN upgrades. Motivated by this fact, we study theoretical predictions for elastic electron scattering in the N=82, N=50, and N=14 isotonic chains from very proton-deficient to very proton-rich isotones. We compute the scattering observables by performing Dirac partial-wave calculations. The charge density of the nucleus is obtained with a covariant nuclear mean-field model that accounts for the low-energy electromagnetic structure of the nucleon. For the discussion of the dependence of scattering observables at low-momentum transfer on the gross properties of the charge density, we fit Helm model distributions to the self-consistent mean-field densities. We find that the changes shown by the electric charge form factor along each isotonic chain are strongly correlated with the underlying proton shell structure of the isotones. We conclude that elastic electron scattering experiments in isotones can provide valuable information about the filling order and occupation of the single-particle levels of protons.Comment: 13 pages; 19 figure