Self-Similar Polytropic Champagne Flows in H II Regions

We explore large-scale hydrodynamics of H II regions for various self-similar shock flows of a polytropic gas cloud under self-gravity and with quasi-spherical symmetry. We formulate cloud dynamics by invoking specific entropy conservation along streamlines and obtain global self-similar "champagne flows" for a conventional polytropic gas with shocks as a subclass. Molecular cloud cores are ionized and heated to high temperatures after the onset of nuclear burning of a central protostar. We model subsequent evolutionary processes in several ways and construct possible self-similar shock flow solutions. We may neglect the mass and gravity of the central protostar. The ionization and heating of the surrounding medium drive outflows in the inner cloud core and a shock travels outwards, leading to the so-called "champagne phase" with an expanding outer cloud envelope. Complementarily, we also consider the expansion of a central cavity around the centre. As the inner cloud expands plausibly due to powerful stellar winds, a cavity (i.e., `void' or `bubble') can be created around the centre, and when the cavity becomes sufficiently large, one may neglect the gravity of the central protostar. We thus present self-similar shock solutions for "champagne flows" with an expanding central void. We compare our solutions with isothermal solutions and find that the generalization to the polytropic regime brings about significant differences of the gas dynamics, especially for cases of n<1, where n is a key scaling index in the self-similar transformation. We also compare our global polytropic self-similar solutions with numerical simulations on the expansion of H II regions.Comment: 17 pages, 10 figures, accepted for publication by MNRA

General Polytropic Magnetofluid under Self-Gravity: Voids and Shocks

We study the self-similar magnetohydrodynamics (MHD) of a quasi-spherical expanding void (viz. cavity or bubble) in the centre of a self-gravitating gas sphere with a general polytropic equation of state. We show various analytic asymptotic solutions near the void boundary in different parameter regimes and obtain the corresponding void solutions by extensive numerical explorations. We find novel void solutions of zero density on the void boundary. These new void solutions exist only in a general polytropic gas and feature shell-type density profiles. These void solutions, if not encountering the magnetosonic critical curve (MCC), generally approach the asymptotic expansion solution far from the central void with a velocity proportional to radial distance. We identify and examine free-expansion solutions, Einstein-de Sitter expansion solutions, and thermal-expansion solutions in three different parameter regimes. Under certain conditions, void solutions may cross the MCC either smoothly or by MHD shocks, and then merge into asymptotic solutions with finite velocity and density far from the centre. Our general polytropic MHD void solutions provide physical insight for void evolution, and may have astrophysical applications such as massive star collapses and explosions, shell-type supernova remnants and hot bubbles in the interstellar and intergalactic media, and planetary nebulae.Comment: 21 pages, 15 figures, accepted for publication on New Astronom

Navidades circenses

Este proyecto consiste en unas actividades extra escolares relacionadas con la educación física en las cuales se realizan conjuntamente malabares y acrosport. El proyecto finaliza con una exposición final en la que los alumnos muestran todo lo aprendido durante estos días. Además se entrega a los padres de cada alumno un informe personalizado en el que aparece un seguimiento individualizado de cada alumno

Aproximación a los estereotipos existentes sobre la esquizofrenia

El interés de este Trabajo de Fin de Grado consiste en conocer las opiniones que la población general tiene sobre la esquizofrenia. Para ello, y tras realizar un análisis bibliográfico, se utilizará la encuesta y el grupo de discusión como técnicas de recogida de datos. Finalmente, se comparará este estudio con otro similar, y se introduce la aportación de una campaña para reducir el estigma en la esquizofrenia

Acciones de grupos finitos. Grupos primitivos.

En este TFG se expone la relación entre grupos finitos de permutaciones y grupos asbtractos, a través de las acciones, así como la propiedad de primitividad de grupos, una propiedad de grupos de permutaciones, la cual es trasladada a grupos asbtractos por medio de estas. Por último, damos el teorema de Baer, que nos proporciona una clasificación de los grupos primitivos, una propiedad definida en términos de subgrupos maximales, según la estructura de sus subgrupos normales minimales. Así pues, hay tres tipos de grupos primitivos, de los cuales daremos ejemplos, y estudiaremos tanto sus subgrupos maximales como sus subgrupos normales minimales.<br /

Modelado cinético de la oxidación de los isómeros del butanol

Se ha realizado una simulación de la reacción de oxidación de los isómeros del butanol, siguiendo de cerca el trabajo experimental llevado a cabo por los investigadores del I3A. En este proyecto se han analizado los resultados de las simulaciones de varios modelos cinéticos de bibliografía, y se ha actuado sobre un modelo cinético desarrollado en el I3A con el fin de actualizarlo y optimizarlo

Uso de la nanotecnología para descubrir materiales del Patrimonio Cultural

La ovoalbúmina y el colágeno son proteínas que históricamente han estado muy presentes en los aglutinantes utilizados en las pinturas. Detectar su presencia es fundamental para poder realizar una conservación adecuada de las obras de arte, aunque para ello hay que lidiar con la degradación a la que se ven sometidas durante el paso del tiempo y con el pequeño tamaño muestral de que se dispone. En este estudio se han sentado las bases del desarrollo de un nanobiosensor capaz de detectar dichas proteínas específicamente en muestras con muy poca concentración de proteína. Para ello se ha combinado la especificidad de los anticuerpos como elementos de detección, con la capacidad de las nanopartículas de oro de actuar como elementos de transducción de señal. Los resultados obtenidos han permitido optimizar el diseño del biosensor mencionado, paso necesario para conseguir un análisis de muestras reales eficaz

A cross-sectional study examining the parametric thyroid feedback quantile index and its relationship with metabolic and cardiovascular diseases

The usual inverse correlation between thyrotropin (TSH) and thyroid hormone disappears in syndromes of central resistance to thyroid hormone, where both are high. TSH and thyroid hormone are also simultaneously high when there is an elevation of the set point of the thyroid regulation axis. This can be estimated with indices, such as the Parametric Thyroid Feedback Quantile-based Index (PTFQI), which was designed for the general population. The PTFQI is positively associated with diabetes prevalence, but association with other pathologies has not been yet explored. The aim of this project was to explore the potential relationship of the PTFQI with metabolic and cardiovascular disease in a sample of ambulatory adult patients from Spain

Robust control strategies for multi-inventory systems with average flow constraints.

In this paper, we consider multi-inventory systems in the presence of uncertain demand. We assume that (i) demand is unknown but bounded in an assigned compact set and (ii) the control inputs (controlled flows) are subject to assigned constraints. Given a long-term average demand, we select a nominal flow that feeds such a demand. In this context, we are interested in a control strategy that meets at each time all possible current demands and achieves the nominal flow in the average. We provide necessary and sufficient conditions for such a strategy to exist and we characterize the set of achievable flows. Such conditions are based on linear programming and thus they are constructive. In the special case of a static flow (i.e. a system with 0-capacity buffers) we show that the strategy must be affine. The dynamic problem can be solved by a linear-saturated control strategy (inspired by the previous one). We provide numerical analysis and illustrative examples

An elevated parametric thyroid feedback quantile-based index is associated with atrial fibrillation

Atrial fibrillation is associated with hyperthyroidism. Within the euthyroid range, it is also associated with high thyroxine (fT4), but not with thyrotropin (TSH). We aim to describe differences in thyroid regulation, measured by the Parametric Thyroid Feedback Quantile-Based Index (PTFQI), between patients with atrial fibrillation and the general population. Materials and methods: Thyroid parameters (PTFQI, TSH, and fT4) of a sample of 84 euthyroid subjects with atrial fibrillation (cases) were compared to a reference sample of euthyroid healthcare patients (controls). We calculated age and sex adjusted ORs for atrial fibrillation across tertiles of these parameters. Also, within cases, we studied thyroid parameters association with clinical characteristics of the atrial fibrillation. Results: After adjusting for age and sex, fT4 and PTFQI were higher in subjects with atrial fibrillation when compared to the general sample (p&amp;lt;0.01 and p=0.01, respectively). Atrial fibrillation ORs of the third versus the first PTFQI tertile was 1.88(95%CI 1.07,3.42), and there was a gradient across tertiles (p trend=0.02). Among atrial fibrillation patients, we observed that higher PTFQI was associated with sleep apnea/hypopnea syndrome (OSAS) (p=0.03), higher fT4 was associated with the presence of an arrhythmogenic trigger (p=0.02) and with heart failure (p&amp;lt;0.01), and higher TSH was also associated with OSAS (p&amp;lt;0.01). Conclusions: Euthyroid subjects with atrial fibrillation have an elevation of the pituitary TSH-inhibition threshold, measured by PTFQI, with respect to the general population. Within atrial fibrillation patients, high PTFQI was associated with OSAS, and high fT4 with heart failure. These results hint of the existence of a relationship between thyroid regulation and atrial fibrillation