Peer Victimization in Overweight Adolescents and Its Effect on Their Self-Esteem and Peer Difficulties

This study has three objectives: to examine whether adolescents who perceive themselves as overweight differ from others in terms of offline victimization at school, cybervictimization, self-esteem, and difficulties relating to peers; to examine the possible effects of offline and cybervictimization on self-esteem and difficulties relating to peers; and to examine the possible moderating role of perceiving oneself as overweight on those effects. Previously validated questionnaires were applied to a sample of 3145 adolescents in Asturias (Spain). Descriptive, inferential, correlational, and structural equation analyses were performed. Adolescents who perceived themselves as overweight reported being victims of both offline victimization and most forms of cybervictimization to a greater extent than those who did not perceive themselves as overweight. They also reported lower self-esteem and more peer difficulties (shyness or social anxiety). In both groups of adolescents, victimization and cybervictimization were correlated with each other, both types of victimization had direct, negative effects on self-esteem, and self-esteem in turn had a direct, negative effect on peer difficulties. Furthermore, offline victimization had a direct, positive effect on peer difficulties. Perceiving oneself as overweight moderated the effect of self-esteem on peer difficulties. In adolescents perceiving themselves as overweight, low self-esteem was a stronger risk factor of peer difficulties than in the rest of the adolescents. With high overall self-esteem there were no significant differences in peer difficulties between the adolescents perceiving themselves as overweight and the rest of the adolescents

An Empirical Analysis of the Matching Process in the Spanish Public Employment Agencies: The Vacancies

Our work tries to assess the degree to which the matching process of the vacancies managed by the Andalusian public employment agencies (SAE) approaches a theoretical model of the stock-flow type as described by Coles (1994, CEPR) and his collaborators. According to this model, a new vacancy can be "good" (relatively scarce in its labour segment) or "bad" (relatively abundant in its labour segment); this unobservable heterogeneity at the aggregate level determines the probability of coverage of the vacancy and the characteristics of the worker who occupies it. For our study, we work with a sample of 3.565 vacancies registered in the SAE between March 2006 and October 2008. The proposed test requires the estimation of a duration model for the hazard rate of vacancies with multiple exits. A novelty of our test is that it does not require information about the entire stock and flow of candidates of the other side of the market. The main result obtained is the existence of certain evidence in favour of stock-flow matching.Public employment agencies, Matching, Vacancies, Duration models, Stock-flow model.

Un análisis de las duraciones de los puestos vacantes gestionados por el Servicio Andaluz de Empleo.Emparejamiento stck-flow frente al emparejamiento aleatorio.

Nuestro trabajo tiene fundamentalmente dos objetivos. El primero consiste en analizar con detalle qué características y probabilidades de empleo presentan los puestos vacantes gestionados por el Servicio Andaluz de Empleo (SAE). El segundo consiste en contrastar en qué grado el proceso de emparejamiento de estos puestos gestionados se aproxima a un modelo teórico del tipo “stock-flow”, tal como es descrito por Coles (1994, CEPR). Según este modelo, un puesto nuevo puede ser “bueno” (escaso en su segmento laboral) o “malo” (abundante en su segmento laboral); esta heterogeneidad inobservable condiciona la probabilidad del puesto de ser cubierto y las características del trabajador que lo ocupa. Para nuestro estudio contamos con una muestra de 3565 puestos vacantes inscritos en el SAE entre marzo de 2006 y octubre de 2008. El contraste propuesto requiere la estimación de un modelo de duración para la tasa de salida de las vacantes con salida múltiple. El principal resultado obtenido es la existencia de cierta evidencia en favor del emparejamiento “stock-flow”.Emparejamiento laboral, vacantes, duraciones modelo stock.flow, servicio andaluz de empleo

Nuevos parámetros para caracterizar los estados de fragilidad del acero : memoria para optar al grado de Doctor en Química Industrial

Tesis de la Universidad de Madrid, Facultad de Ciencias, Sección de Químicas, 1969.Fac. de Ciencias QuímicasTRUEProQuestpu

Object Tracking from Unstabilized Platforms by Particle Filtering with Embedded Camera Ego Motion

Visual tracking with moving cameras is a challenging task. The global motion induced by the moving camera moves the target object outside the expected search area, according to the object dynamics. The typical approach is to use a registration algorithm to compensate the camera motion. However, in situations involving several moving objects, and backgrounds highly affected by the aperture problem, image registration quality may be very low, decreasing dramatically the performance of the tracking. In this work, a novel approach is proposed to successfully tackle the tracking with moving cameras in complex situations, which involve several independent moving objects. The key idea is to compute several hypotheses for the camera motion, instead of estimating deterministically only one. These hypotheses are combined with the object dynamics in a Particle Filter framework to predict the most probable object locations. Then, each hypothetical object location is evaluated by the measurement model using a spatiogram, which is a region descriptor based on color and spatial distributions. Experimental results show that the proposed strategy allows to accurately track an object in complex situations affected by strong ego motion

La función de emparejamiento en el mercado de trabajo español

En este trabajo analizamos el proceso de emparejamiento existente en el Servicio Público de Empleo Estatal (INEM). Dicho organismo constituye un claro ejemplo de mercado donde las colocaciones en cada período emparejan a los flujos de nuevos demandantes de empleo y puestos vacantes con los correspondientes stocks al comienzo del mes. Esta dinámica de emparejamiento se conoce con el nombre de modelo stock-flow. Para contrastar el emparejamiento stock-flow frente al emparejamiento aleatorio se estiman, tratando el problema de la agregación temporal, diversas especificaciones de la función de emparejamiento durante el período 1978:01-2005:04. Previamente, ha sido necesario realizar ciertas intervenciones en las series utilizadas. Los resultados obtenidos, robustos temporal y geográficamente, están muy próximos al caso de emparejamiento stock-flow con trabajadores “en cola”. Dichos resultados invitan a potenciar las políticas activas del mercado de trabajo.mercado de trabajo español, Servicio Público de Empleo Estatal (INEM), función de emparejamiento.

Robust automatic target tracking based on a Bayesian ego-motion compensation framework for airborne FLIR imagery

Automatic target tracking in airborne FLIR imagery is currently a challenge due to the camera ego-motion. This phenomenon distorts the spatio-temporal correlation of the video sequence, which dramatically reduces the tracking performance. Several works address this problem using ego-motion compensation strategies. They use a deterministic approach to compensate the camera motion assuming a specific model of geometric transformation. However, in real sequences a specific geometric transformation can not accurately describe the camera ego-motion for the whole sequence, and as consequence of this, the performance of the tracking stage can significantly decrease, even completely fail. The optimum transformation for each pair of consecutive frames depends on the relative depth of the elements that compose the scene, and their degree of texturization. In this work, a novel Particle Filter framework is proposed to efficiently manage several hypothesis of geometric transformations: Euclidean, affine, and projective. Each type of transformation is used to compute candidate locations of the object in the current frame. Then, each candidate is evaluated by the measurement model of the Particle Filter using the appearance information. This approach is able to adapt to different camera ego-motion conditions, and thus to satisfactorily perform the tracking. The proposed strategy has been tested on the AMCOM FLIR dataset, showing a high efficiency in the tracking of different types of targets in real working conditions

Automatic Feature-Based Stabilization of Video with Intentional Motion through a Particle Filter

Video sequences acquired by a camera mounted on a hand held device or a mobile platform are affected by unwanted shakes and jitters. In this situation, the performance of video applications, such us motion segmentation and tracking, might dramatically be decreased. Several digital video stabilization approaches have been proposed to overcome this problem. However, they are mainly based on motion estimation techniques that are prone to errors, and thus affecting the stabilization performance. On the other hand, these techniques can only obtain a successfully stabilization if the intentional camera motion is smooth, since they incorrectly filter abrupt changes in the intentional motion. In this paper a novel video stabilization technique that overcomes the aforementioned problems is presented. The motion is estimated by means of a sophisticated feature-based technique that is robust to errors, which could bias the estimation. The unwanted camera motion is filtered, while the intentional motion is successfully preserved thanks to a Particle Filter framework that is able to deal with abrupt changes in the intentional motion. The obtained results confirm the effectiveness of the proposed algorith

Los datos de la Estadística de Empleo del INEM y la estimación de la función de emparejamiento para la economía española

En este trabajo analizamos, en primer lugar, los datos publicados en la Estadística de Empleo del INEM, y las posibilidades y problemas que plantea su utilización en los estudios sobre el mercado de trabajo español basados en el enfoque de flujos. Utilizando estos datos realizamos varias estimaciones de la función de emparejamiento, tras una discusión de la metodología más apropiada. El resultado principal es que el emparejamiento en este ámbito se aproxima al caso especial de trabajadores en cola. Finalmente apuntamos las principales dificultades a la hora de estimar la función de emparejamiento con datos totales de la economía española.mercado de trabajo español, Instituto Nacional de Empleo (INEM), flujos, emparejamiento, vacantes, agregación temporal, stock-flow.

SEASONAL VARIATION IN BIRD ASSEMBLAGE COMPOSITION IN A DRY FOREST OF SOUTHWESTERN MEXICO

Abstract · Tropical dry forests are characterized by a marked seasonality throughout the year. The response of bird assemblages and species abundance to the seasonal changes of dry forests, as evidenced by bird feeding habits, can contribute to a greater understanding of the ecological processes in this ecosystem. In this study, we estimated variations in richness, abundance and composition of bird assemblages as well as their main feeding habits during two seasons of the year (dry and rainy) in a tropical dry forest in southwestern Mexico. Visual and auditory sampling was performed from February 2010 to February 2011 with a fixed-radius point count method (123 point counts distributed across nine transects). A total of 82 bird species belonging to 28 families were recorded in the study area. Although we found more species and a higher abundance in the dry season than in the rainy season, only the abundance of insectivorous-frugivorous and omnivorous birds was significantly higher. According to an ordination analysis, the composition and abundance of bird assemblage changed seasonally. A total of 21 resident birds were found in the dry season (March–June). Some omnivorous and granivorous birds, such as Streak-backed Oriole (Icterus pustulatus) and Blackchested Sparrow (Peucaea humeralis), were the most abundant species in both seasons. Other species, such as Western Kingbird (Tyrannus verticalis) and Golden-cheeked Woodpecker (Melanerpes chrysogenys), both insectivorous-frugivorous, were also abundant in two seasons. The greater diversity of avian feeding guilds in the dry season could be influenced by the reproductive activity that occur during this season and by the presence of Bursera fruits, as confirmed in other studies. Resumen · Variación estacional en la composición de ensambles de aves en un bosque tropical seco del suroeste de México Los bosques tropicales secos se caracterizan por una marcada estacionalidad climática a lo largo del año. Comprender la respuesta de los ensambles de aves y la abundancia de las especies de acuerdo a sus hábitos de alimentación, respecto a los cambios estacionales en el bosque seco, contribuye al conocimiento de los procesos ecológicos en este ecosistema. En este estudio, estimamos la variación de la riqueza, abundancia y composición de las aves y sus tipos de dieta en dos estaciones del año (secas y lluvias) en un bosque tropical seco al suroeste de México. Se realizaron muestreos visuales y auditivos durante un año (febrero de 2010 a febrero de 2011), con el uso de puntos de conteo de radio fijo (123 puntos distribuidos en nueve transectos). Se registró un total de 82 especies de aves que pertenecen a 28 familias. La estación seca presentó mayor riqueza de especies y abundancia de aves que la estación lluviosa, pero solo la abundancia de las aves insectívoro-frugívoras y omnívoras fue significativamente mayor en la estación seca. De acuerdo al análisis de ordenación, la composición y abundancia del ensamble de aves cambió estacionalmente. Se encontró un total de 21 aves residentes en los meses secos del año, que corresponde a la temporada reproductiva (marzo–junio). Algunas aves omnívoras y granívoras como la calandria dorso rayado (Icterus pustulatus) y el zacatonero pecho negro (Peucaea humeralis) fueron las más abundantes en ambas temporadas. Otras especies como tirano pálido (Tyrannus verticalis) y carpintero enmascarado (Melanerpes chrysogenys), ambas insectívoro-frugívoras, también fueron abundantes en las dos estaciones. La mayor diversidad de gremios alimenticios de las aves en la estación seca podría estar influenciada por las actividades reproductivas que transcurren durante esta temporada, y por la presencia de frutos de Bursera spp., como se ha observado en otros estudios