Non-detection of magnetic fields in the central stars of the planetary nebulae NGC 1360 and LSS 1362

The presence of magnetic fields is an attractive hypothesis for shaping PNe. We report on observations of the central star of the two Planetary Nebulae NGC1360 and LSS1326. We performed spectroscopy on circularly polarized light with the FOcal Reducer and low dispersion Spectrograph at the Very Large Telescope of the European Southern Observatory. Contrary to previous reports (Jordan et al. 2005, A&A, 432, 273), we find that the effective magnetic field, that is the average over the visible stellar disk of longitudinal components of the magnetic fields, is null within errors for both stars. We conclude that a direct evidence of magnetic fields on the central stars of PNe is still missing --- either the magnetic field is much weaker (< 600 G) than previously reported, or more complex (thus leading to cancellations), or both. Certainly, indirect evidences (e.g., MASER emission) fully justify further efforts to study the strength and morphology of such magnetic fields.Comment: Published in ApJ letters: Leone et al. 2011, ApJ, 731, 33

Photodissociation in proto-planetary nebulae. Hydrodynamical simulations and solutions for low-velocity multi-lobes

We explore the effects of photodissociation at the stages of post-asymptotic giant branch stars to find a mechanism able to produce multi-polar shapes. We perform two-dimensional gasdynamical simulations to model the effects of photodissociation in proto-planetary nebulae. We find that post-asymptotic giant branch stars with 7,000 K or hotter are able to photodissociate a large amount of the circumstellar gas. We compute several solutions for nebulae with low-velocity multi-lobes. We find that the early expansion of a dissociation front is crucial to understand the number of lobes in proto-planetary nebulae. A dynamical instability appears when cooling is included in the swept-up molecular shell. This instability is similar to the one found in photoionization fronts, and it is associated with the thin-shell Vishniac instability. The dissociation front exacerbates the growth of the thin-shell instability, creating a fast fragmentation in shells expanding into media with power-law density distributions such as r^-2.Comment: 4 pages, 2 figures, acepted by A&A Letter

How humans take decisions: financial markets as a case of study

Treballs Finals de Grau de Física, Facultat de Física, Universitat de Barcelona, Any: 2015, Tutor: Josep PerellóFinancial markets are a clear example of a choice-dealing situation in which people have to make decisions facing uncertainty and risk. This study aims to learn how people make decisions, in order to predict them, by analysing the data collected in a social experiment and using tools of information theory and statistics. It focuses on how people's own experience ifluence their next actions and what strategies are developed finding that both the market and the previous results in uence decisions with a mutual information value of 0:045 0:010 bits and 0:050 0:010 bits respectively and that these two stochastic processes add non-redundant information to each other. Besides, in the experiment, people's memory holds for only one round. Finally, the 'toy' model tested gives a 55:200 0:016% success ratio for the market's ifluence and a 53:496 0:016% for the results influence analysis

La dimensión mediterránea de la proyección exterior de Cataluña: el Arco Latino

La región mediterránea constituye uda de las áreas de la actividad exterior de Cataluña que mayor protagonismo esta adquiriendo en los últimos tiempos. La proyección exterior catalana, en su dimensión mediteránea, se caracteriza por perseguir, principalmente, objetivos de carácter económico. Por ello se articula alrededor del eje europeo-mediterráneo, el Arco Latino. Sin embargo, no pierde de vista la globalidad de la región ni la oponunidad y la necesidad de estrechar los vínculos con los paises de la costa sur del Mediterráneo.The Mediterranean region is one of the areas which are taking more and more importance in the context of the external activity of Catalonia. The goals of the Catalonian external activity in its Mediterranean dimemnsion are, mainly, of an economic character. That is why, this activity is articulated around the European-Mediteranean axis, the Latin Arch. However, it does not mean that Catalonia's external acivity forgets the idea of globality of the region and, consequently, the opportunity and necessity of enforcing the relations with the South Mediterranean countries

Reestructuración de la GUI y de los algoritmos de correlación de curvas para un sistema CBIR

This thesis presents a system for recognizing individual elephants. This work has been done in collaboration with a group of researchers from the Department of Zoology of University La Sapienza, which deals with the study of the behavior of the specie. Being able to identify different specimens within a group is to study the characteristics (habits, movements, life expectancy etc.). To date, this recognition takes place by observing and comparing the photos taken in African parks in different periods. This stage is increasingly made more difficult by the fact that individuals differ among themselves for very few details. One of these is the presence of nicks on their ears. The shape and position of nicks appears to have been a distinctive feature almost like fingerprints for mankind. Figure 1 shows an example of two individuals distinguished by the different shape of the profile of the ear. The aim was to create a system that automates this process of recognition. The initial system was created by A. Ardovini. In this second version of the system a new algorithm has been implemented that allows for greater automation of the process. Consequently, some aspects of the GUI have changed, resulting in a more user-friendly interface. The system presented here extracts the profile of the ear identifying the nicks and, through a technique of edge-matching, profiles most similar to it are selected from the database. The process of recognition of an individual is composed of four basic steps. The first step consists in the extraction of the profile of the individual through a semi-automatic edge-detection operation, and the selection of nicks in the profile itself. The nicks selected become part of a vector query. In the next step all profiles in the database corresponding to the same side of the query are considered. These profiles must have at least one nick in a position similar to one of those of the profile input. The third step is to compare the query curves with the edge of the profiles previously selected. The last step allows the extraction of a final ranking of N individuals based on their similarity with the profile input. This thesis is organized as follows. In chapter 2 some existing methods in literature are introduced. In chapter 3 some existing systems are reviewed, and particularly the work whose approach is the closest to our system is presented in greater depth. In chapter 4 the architecture of the proposed system is described. Chapter 5 presents the database structure and methods of insertion. In chapter 6 the experimental results are presented and finally in chapter 7 an example of the use of our system is showed. _______________________________________________________________________________Esta tesis presenta un sistema para el reconocimiento de elefantes. Este trabajo ha sido realizado en colaboración con un grupo de investigadores del Departamento de Zoología de la Universidad La Sapienza, que trata del estudio del comportamiento de la especie. Ser capaz de identificar diferentes especímenes dentro de un grupo es estudiar las características (hábitos, movimientos, esperanza de vida, etc). Hasta la fecha, este reconocimiento se lleva a cabo mediante la observación y la comparación de las fotos tomadas en los parques africanos en diferentes períodos. Esta etapa es cada vez más difícil por el hecho de que los individuos difieren entre sí por muy pocos detalles. Una de ellas es la presencia de muescas en las orejas. La forma y posición de dichas muescas parece ser un rasgo distintivo casi como las huellas dactilares para los humanos. El objetivo era crear un sistema que automatizase este proceso de reconocimiento. El sistema inicial fue creado por A. Ardovini. En esta segunda versión del sistema se ha aplicado un nuevo algoritmo que permite una mayor automatización del proceso. En consecuencia, algunos aspectos de la interfaz gráfica de usuario han cambiado, resultando en una interfaz más eficaz y amigable. El sistema que se muestra aquí extrae el perfil de la oreja, identificando los cortes y, a través de una técnica de correlación de bordes son seleccionados los perfiles de la base de datos más similares a cada oreja. El proceso de reconocimiento de un individuo se compone de cuatro pasos básicos. El primer paso consiste en la extracción del perfil del individuo a través de un operación de detección de bordes semi-automática, y la selección de las muescas de dicho perfil. Las muescas seleccionadas pasan a formar parte de un vector de consulta. En el siguiente paso todos los perfiles de la base de datos correspondiente al mismo lado de la consulta se consideran. Estos perfiles deben tener al menos una muesca en una posición similar a una de las de la entrada del perfil. El tercer paso es comparar las curvas de consulta con el borde de los perfiles previamente seleccionados. El último paso permite la extracción de una clasificación final de N individuos sobre la base de su similitud con la entrada de perfil.Ingeniería en Informátic

Photonic molecules for improving the optical response of macroporous silicon photonic crystals for gas sensing purposes

In this paper, we report the benefits of working with photonic molecules in macroporous silicon photonic crystals. In particular, we theoretically and experimentally demonstrate that the optical properties of a resonant peak produced by a single photonic atom of 2.6 µm wide can be sequentially improved if a second and a third cavity of the same length are introduced in the structure. As a consequence of that, the base of the peak is reduced from 500 nm to 100 nm, while its amplitude remains constant, increasing its Q-factor from its initial value of 25 up to 175. In addition, the bandgap is enlarged almost twice and the noise within it is mostly eliminated. In this study we also provide a way of reducing the amplitude of one or two peaks, depending whether we are in the two- or three-cavity case, by modifying the length of the involved photonic molecules so that the remainder can be used to measure gas by spectroscopic methods.Postprint (published version

Personajes y discurso emocional en las campañas de la DGT. Análisis de los spots de 2007-2011

This work shows the importance of emotional appeal in persuasive medium for spots of Spanish traffic Department from 2007-2011, and I identify the emotions represented in the visual speech, the subject profile of these emotions, and their relationship with the object of spot. The methodology has been: content analysis, quantitative and qualitative, based on direct observation of a number of selected variables, and treated statistically, absolutely and in relation to other values.En este trabajo se muestra la importancia de la apelación emocional como medio persuasivo en los spots publicitarios de la Dirección General de Tráfico desde 2007 hasta 2011, identificando las emociones más representadas en el discurso audiovisual, el perfil del sujeto de dichas emociones, y su relación con el objeto del spot. La metodología utilizada ha sido la del análisis de contenido, cuantitativo y cualitativo, partiendo de la observación directa de una serie de variables seleccionadas, tratadas después estadísticamente, de forma absoluta y en relación con otros valores

La "mirada cosmopolita" como requisito político y social para la provisión de los bienes públicos globales

En un mundo globalizado, el bienestar de los ciudadanos ya no depende exclusivamente de la provisión de bienes públicos por parte de sus gobiernos sino que, ante la extensión y la magnitud global de los problemas y de los retos a la seguridad, éste depende de Bienes Públicos Globales que, por su naturaleza, sólo pueden ser provistos a través de mecanismos de gobernanza global. En la búsqueda de la gobernanza global, los Bienes Jurídicos Globales –Bienes Públicos Globales de carácter intermedio– son fundamentales para la provisión y garantía de los Bienes Públicos Globales finales y la «mirada cosmopolita» (U. Beck) es el requisito político y social imprescindible para alcanzarlos. La «mirada cosmopolita » supone la toma de conciencia de ciudadanos y gobiernos del carácter global de los problemas percibidos y asumidos como comunes (Males Públicos Globales) y la decisión de trabajar conjuntamente para transformarlos en Bienes Públicos Globales