Diseño y construcción de un dispositivo portátil para medición del centro de presión del cuerpo humano

Tesis que describe el diseño, construcción y validación de un sistema electrónico para la evaluación del equilibrio en humanosEl estudio del equilibrio humano es útil para el diagnóstico y seguimiento de diversas patologías como: enfermedades neurológicas (Parkinson, Alzheimer, etc.), alteraciones del sistema músculo-esquelético debidas a razones como: uso de tacones altos, sobrepeso, envejecimiento, inestabilidades posturales, uso de prótesis, etc. Existen numerosas herramientas para valorar cualitativa y cuantitativamente el equilibrio. La mayoría se basa en la medición del CoP (Centro de Presión, por sus siglas en inglés), este parámetro depende a su vez de la posición del CoM (Centro de Masa), la cual es la variable monitoreada y controlada por el Sistema Nervioso Central (SNC) para mantener el equilibrio. Las herramientas cualitativas (observación) son propensas a errores de apreciación por falta de experiencia, cansancio o descuido del evaluador. Las cuantitativas suelen ser muy voluminosas (1 a 2 m 3 y más de 4 kg), costosas (superiores a los 3,000 USD) y por tanto limitadas a su uso en laboratorios especializados. Otras soluciones cuantitativas (plantillas instrumentadas) son más económicas pero son personalizadas para un solo sujeto, lo cual nuevamente limita su impacto en el análisis del equilibrio en grandes poblaciones. En esta tesis se presenta el diseño y construcción de un dispositivo portátil y de bajo costo para evaluar el CoP. El prototipo presentado se basa en 3 sensores FSR (Force Sensing Resistor) por pie en una configuración geométrica tomando como base las regiones donde se concentra el mayor peso del cuerpo. Mediante la adecuación de un algoritmo se obtuvo un cálculo para obtener el CoP basado en esos sensores. El sistema está diseñado para adaptarse a pies de 22 a 29 cm de longitud. La estimación del CoP y de los distintos índices comúnmente usados en el diagnóstico y seguimiento de diversas patologías, son calculados en un sistema embebido y desplegados en una pantalla TFT (Thin Film Transistor). Lo anterior asegura un sistema adaptable, portátil y de bajo costo comparado con los sistemas existentes en el estado del arte. El sistema se utilizó para medir el CoP de 50 sujetos de entre 20 y 39 años de edad (33 hombres y 17 mujeres) cuya edad y peso promedio son (26.04 ± 4.94 años, 68.37 ± 8.15 kg) respectivamente. Los resultados promedio obtenidos se compararon con los reportados en diversos estudios para sujetos con características similares. Éstos indican que el sistema aquí presentado es capaz de medir el CoP, obteniendo resultados similares a los que presentan sistemas basados en plataformas de fuerza (Golden Standard). Se encontró además que el sistema es capaz de discriminar entre sujetos en posición de pie, con ojos cerrados y sujetos con ojos abiertos (p < 0001), diferencia que por criterios convencionales se considera estadísticamente significativa

Posibilidades de acceso de niños y jóvenes con discapacidad mental a prácticas corporales en ámbitos no formales como derecho a la integración

El siguiente trabajo pretende reflexionar a la luz de algunas de las realidades actuales en cuestión de accesibilidad a prácticas corporales de niños y jóvenes con discapacidad mental. Los datos que nos permiten analizar estas cuestiones, surgen de una investigación en proceso destinada a una tesis de maestría y son aportados desde el Instituto de Educación Especial Helen Keller, que brinda atención pedagógica y talleres de cerámica a contra turno y cuenta con una numerosa matricula, la reflexión se basa sobre cuatro puntos de análisis en cuestiones de accesibilidad. 1- Realidad Social de niños y jóvenes con discapacidad mental que concurren al Instituto de Educación Especial Helen Keller. 2- La mirada de la medicina sobre la discapacidad 3- La integración. 4- El estado y sus políticas publicas de acceso a practicas corporale

Salinity Transport in a Finite-Volume Sigma-Layer Three-Dimensional Model

The objective of this study was to develop a 3-D model for The Pontchartrain Estuary that was capable of long-term mass conservative simulation of salinities. This was accomplished in a multi-stage approach involving: a physical model of salinity exchange through a pass; a 3-D FVCOM model of the physical experiment; the development and testing of an FVCOM model for an idealized Pontchartrain Basin; and for the entire estuary. The data from the physical model tests were used to validate the performance of the FVCOM model with density-driven flows. These results showed that hydrostatic FVCOM captured the primary internal wave movement. The idealized basin simulations were used to evaluate several issues related to salinity transport, namely the relative importance of baroclinic forcing, tidal forcing and hydrology. The idealized domain also permitted the testing of sigma-gradients, spatial distribution of friction coefficients, wind stress and various boundary treatments. The results showed that the density-driven exchange of saltwater at the open boundary required a baroclinic boundary condition for salinity as well as a lateral filter at the boundary on each sigma layer. A new radiative baroclinic open boundary condition was developed for FVCOM. When tides and hydrology were included, the FVCOM model was shown to reproduce the seasonal salinity that has been observed for long-term periods. It was also found that the simulation of tides and salinity in FVCOM is very sensitive to the spatial distribution of the friction coefficient; relatively low friction was required in the open water regions and high friction was needed in the passes and waterways to reproduce the tides and salinity distribution. A variable friction coefficient option was coded on FVCOM. The findings from the idealized model were utilized to setup two models for the actual estuary. Both models extend from Lake Maurepas, one to the Chandeleurs Islands and the other to Mobile Bay. The baroclinic open boundary and variable friction were implemented in these models. They were calibrated for tides and salinity. The 2008 Bonnet Carré Spillway Opening was applied to the first model. A tidal pumping effect in Lake Pontchartrain was observed and captured by the model

Salinity Transport in a Finite-Volume Sigma-Layer Three-Dimensional Model

The objective of this study was to develop a 3-D model for The Pontchartrain Estuary that was capable of long-term mass conservative simulation of salinities. This was accomplished in a multi-stage approach involving: a physical model of salinity exchange through a pass; a 3-D FVCOM model of the physical experiment; the development and testing of an FVCOM model for an idealized Pontchartrain Basin; and for the entire estuary. The data from the physical model tests were used to validate the performance of the FVCOM model with density-driven flows. These results showed that hydrostatic FVCOM captured the primary internal wave movement. The idealized basin simulations were used to evaluate several issues related to salinity transport, namely the relative importance of baroclinic forcing, tidal forcing and hydrology. The idealized domain also permitted the testing of sigma-gradients, spatial distribution of friction coefficients, wind stress and various boundary treatments. The results showed that the density-driven exchange of saltwater at the open boundary required a baroclinic boundary condition for salinity as well as a lateral filter at the boundary on each sigma layer. A new radiative baroclinic open boundary condition was developed for FVCOM. When tides and hydrology were included, the FVCOM model was shown to reproduce the seasonal salinity that has been observed for long-term periods. It was also found that the simulation of tides and salinity in FVCOM is very sensitive to the spatial distribution of the friction coefficient; relatively low friction was required in the open water regions and high friction was needed in the passes and waterways to reproduce the tides and salinity distribution. A variable friction coefficient option was coded on FVCOM. The findings from the idealized model were utilized to setup two models for the actual estuary. Both models extend from Lake Maurepas, one to the Chandeleurs Islands and the other to Mobile Bay. The baroclinic open boundary and variable friction were implemented in these models. They were calibrated for tides and salinity. The 2008 Bonnet Carré Spillway Opening was applied to the first model. A tidal pumping effect in Lake Pontchartrain was observed and captured by the model

On the electronic structure of silicene on Ag substrate: strong hybridization effects

The electronic structure of the recently synthesised (3x3) reconstructed silicene on (4x4) Ag(111) is investigated by first-principles calculations. New states emerge due to the strong hybridization between silicene and Ag. Analyzing the nature and composition of these hybridized states, we show that i) it is possible to clearly distinguish them from states coming from the Dirac cone of free-standing silicene or from the sp-bands of bulk Ag and ii) assign their contribution to the description of the linearly dispersing band observed in photoemission. Furthermore, we show that silicene atoms contribute to the Fermi level, which leads to similar STM patterns as observed below or above the Fermi level. Our findings are crucial for the proper interpretation of experimental observations.Comment: 8 pages, 3 figures including supplementary materia

All-optical nonequilibrium pathway to stabilizing magnetic Weyl semimetals in pyrochlore iridates

Nonequilibrium many-body dynamics is becoming one of the central topics of modern condensed matter physics. Floquet topological states were suggested to emerge in photodressed band structures in the presence of periodic laser driving. Here we propose a viable nonequilibrium route without requiring coherent Floquet states to reach the elusive magnetic Weyl semimetallic phase in pyrochlore iridates by ultrafast modification of the effective electron-electron interaction with short laser pulses. Combining \textit{ab initio} calculations for a time-dependent self-consistent reduced Hubbard $U$ controlled by laser intensity and nonequilibrium magnetism simulations for quantum quenches, we find dynamically modified magnetic order giving rise to transiently emerging Weyl cones that are probed by time- and angle-resolved photoemission spectroscopy. Our work offers a unique and realistic pathway for nonequilibrium materials engineering beyond Floquet physics to create and sustain Weyl semimetals. This may lead to ultrafast, tens-of-femtoseconds switching protocols for light-engineered Berry curvature in combination with ultrafast magnetism.Comment: 27 pages including methods and supplementary information, 4 figures, 4 supplementary figure

Plantaciones en Patagonia

Se presenta un contrapunto sobre diferentes aspectos relacionados con las forestaciones en los ecosistemas del norte de la patagonia. Se aborda los principales efectos ambientales que ocasionan las forestaciones, las politicas de subsidios a las plantaciones y los efectos socialkes y economicos que pueden tener las plantacionesFil: Grosfeld, Javier Edgardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Patagonia Norte. Instituto de Investigación En Biodiversidad y Medioambiente; ArgentinaFil: Loguercio, Gabriel Angel. Universidad Nacional de la Patagonia; Argentin