Ultrasonic characterization of the pulmonary venous wall: echographic and histological correlation

Background: Pulmonary vein isolation with radiofrequency catheter ablation techniques is used to prevent recurrences of human atrial fibrillation. Visualization of the architecture at the venoatrial junction could be crucial for these ablative techniques. Our study assesses the potential for intravascular ultrasound to provide this information. Methods and Results: We retrieved 32 pulmonary veins from 8 patients dying from noncardiac causes. We obtained cross-sectional intravascular ultrasound (IVUS) images with a 3.2F, 30-MHz ultrasound catheter at intervals on each vein. Histological cross-sections at the intervals allowed comparisons with ultrasonic images. The pulmonary venous wall at the venoatrial junction revealed a 3-layered ultrasonic pattern. The inner echogenic layer represents both endothelium and connective tissue of the media (mean maximal thickness, 1.4±0.3 mm). The middle hypoechogenic stratum corresponds to the sleeves of left atrial myocardium surrounding the external aspect of the venous media. This layer was thickest at the venoatrial junction (mean maximal thickness, 2.6±0.8 mm) and decreased toward the lung hilum. The outer echodense layer corresponds to fibro-fatty adventitial tissue (mean maximal thickness, 2.15±0.36 mm). We found a close agreement among the IVUS and histological measurements for maximal luminal diameter (mean difference, -0.12±1.3 mm) and maximal muscular thickness (mean difference, 0.17±0.13 mm) using the Bland and Altman method. Conclusions: Our experimental study demonstrates for the first time that IVUS images of the pulmonary veins can provide information on the distal limits and thickness of the myocardial sleeves and can be a valuable tool to help accurate targeting during ablative procedures

Contexto familiar y escolar de los alumnos absentistas de ESO: diferencias en padres y alumnos. Análisis en un centro educativo

Truancy is presented as a socio-educational problem of multiple causes. Wide studies have analyzed his heterogeneous nature based on the information of the absent pupils. However, there are not studies about absenteeism in which the progenitors of the pupils had been involved too. The objectives of this study aimed for knowing the differences between the family and school contexts of the absent and not absent pupils. The study was performed in a high school with more absent pupils compared to other educational centers. The final sample was composed of 17 absent pupils, 19 non absent pupils and their parents. The communication and the family climate between the pupils and their parents, the social integration and the participation in the process of harassment of the pupils were evaluated. The results confirm that there are no differences between the groups in terms of family situation that inform parents and students. By contrast, differences appear in the educational situation explained by both groups. The absent students indicated that their school integration was lower in the dimension of affection, considering they were less accepted by teachers. Also absent students reported exercising more harassing behavior toward peers.El absentismo escolar se presenta como un problema socio-educativo de naturaleza multicausal. Son amplios los estudios que han analizado su naturaleza heterogénea y han contado para ello con la colaboración de los alumnos. Sin embargo, no se conocen estudios sobre absentismo donde se haya dado también participación a sus progenitores. Los objetivos de este estudio se dirigían a conocer las diferencias entre los contextos familiar y escolar de los alumnos absentistas y de los no absentistas en ESO. El estudio se realizó en un instituto que contaba con mayor número de alumnos absentistas respecto de otros centros. La muestra final estuvo compuesta por 17 alumnos absentistas, 19 alumnos no absentistas y sus progenitores. Se evaluó la comunicación y el clima familiar en los alumnos y en sus padres, la integración escolar y la participación en los procesos de acoso de los alumnos. Los instrumentos utilizados fueron Escala de Clima Social Familiar (FES), Cuestionario de Comunicación Familiar (CA-M/CA-P), Cuestionario de Comunicación Familiar para Padres, Cuestionario de Percepción Psicológica de Integración Escolar (PSSM) y Cuestionario de Acoso Escolar (CAME). Se utilizó el paquete estadístico SPSS 19.0 para Windows y se realizaron los análisis estadísticos prueba t de Student para muestras independientes, prueba t de Student para muestras relacionadas y regresión logística binaria para confirmar la implicación de las variables de estudio en el absentismo escolar. Los resultados confirman que no existen diferencias entre ambos grupos en cuanto a la situación familiar que informaban los padres y los alumnos. Por el contrario, sí que aparecen diferencias en cuanto a la situación escolar informada por ambos grupos. Los alumnos absentistas informaron que su integración escolar era menor en la dimensión de afecto, consideraban que eran menos aceptados por los profesores. También los alumnos absentistas informaron que ejercían más conductas de acoso hacia sus compañeros

Necesidad de la acción coordinadora en las zonas rurales para fomentar el emprendimiento femenino

La acción mediadora tiene como finalidad generar actos sustantivos, que en el proyecto planteado, son promover el mantenimiento, la consolidación y el crecimiento de empresas de mujeres e impulsar el emprendimiento femenino en las áreas rurales a través de la utilización de los recursos endógenos locales, fomentando un desarrollo sostenible. Por lo tanto, se enmarca en un aprovechamiento de los recursos endógenos existentes en las comunidades rurales para desarrollar actividades de generación de ingresos para las mujeres (autoempleo o iniciativas empresariales), aprovechando sus conocimientos ecológicos tradicionales respeto a la ordenación de los recursos y a la protección de la diversidad. La acción mediadora de este proyecto está dirigida al colectivo de mujeres rurales por su particular inserción en los mercados laborales y, en general, por la dificultad que en el caso del medio rural existe para separar actividades productivas y reproductivas. Todos los procesos que llevan a que las mujeres rurales se conviertan en sujeto político y objeto de reflexión sociológica conducen, de manera inevitable, al género, como hecho social y como categoría de análisis sociológico

Evershed clouds as precursors of moving magnetic features around sunspots

The relation between the Evershed flow and moving magnetic features (MMFs) is studied using high-cadence, simultaneous spectropolarimetric measurements of a sunspot in visible (630.2 nm) and near-infrared (1565 nm) lines. Doppler velocities, magnetograms, and total linear polarization maps are calculated from the observed Stokes profiles. We follow the temporal evolution of two Evershed clouds that move radially outward along the same penumbral filament. Eventually, the clouds cross the visible border of the spot and enter the moat region, where they become MMFs. The flux patch farther from the sunspot has the same polarity of the spot, while the MMF closer to it has opposite polarity and exhibits abnormal circular polarization profiles. Our results provide strong evidence that at least some MMFs are the continuation of the penumbral Evershed flow into the moat. This, in turn, suggests that MMFs are magnetically connected to sunspots.Comment: To appear in ApJ Letters, Vol 649, 2006 September 20 issu

Temporal evolution of the Evershed flow in sunspots. I. Observational characterization of Evershed clouds

[Abridged] The magnetic and kinematic properties of the photospheric Evershed flow are relatively well known, but we are still far from a complete understanding of its nature. The evolution of the flow with time, which is mainly due to appearance of velocity packets called Evershed clouds (ECs), may provide information to further constrain its origin. Here we undertake a detailed analysis of the evolution of the Evershed flow by studying the properties of ECs. In this first paper we determine the sizes, proper motions, location in the penumbra, and frequency of appearance of ECs, as well as their typical Doppler velocities, linear and circular polarization signals, Stokes V area asymmetries, and continuum intensities. High-cadence, high-resolution, full vector spectropolarimetric measurements in visible and infrared lines are used to derive these parameters. We find that ECs appear in the mid penumbra and propage outward along filaments with large linear polarization signals and enhanced Evershed flows. The frequency of appearance of ECs varies between 15 and 40 minutes in different filaments. ECs exhibit the largest Doppler velocities and linear-to-circular polarization ratios of the whole penumbra. In addition, lines formed deeper in the atmosphere show larger Doppler velocities, much in the same way as the ''quiescent'' Evershed flow. According to our observations, ECs can be classified in two groups: type I ECs, which vanish in the outer penumbra, and type II ECs, which cross the outer penumbral boundary and enter the sunspot moat. Most of the observed ECs belong to type I. On average, type II ECs can be detected as velocity structures outside of the spot for only about 14 min. Their proper motions in the moat are significantly reduced with respect to the ones they had in the penumbra.Comment: Accepted for publication in A&

Temporal evolution of the Evershed flow in sunspots. II. Physical properties and nature of Evershed clouds

Context: Evershed clouds (ECs) represent the most conspicuous variation of the Evershed flow in sunspot penumbrae. Aims: We determine the physical properties of ECs from high spatial and temporal resolution spectropolarimetric measurements. Methods: The Stokes profiles of four visible and three infrared spectral lines are subject to inversions based on simple one-component models as well as more sophisticated realizations of penumbral flux tubes embedded in a static ambient field (uncombed models). Results: According to the one-component inversions, the EC phenomenon can be understood as a perturbation of the magnetic and dynamic configuration of the penumbral filaments along which these structures move. The uncombed inversions, on the other hand, suggest that ECs are the result of enhancements in the visibility of penumbral flux tubes. We conjecture that the enhancements are caused by a perturbation of the thermodynamic properties of the tubes, rather than by changes in the vector magnetic field. The feasibility of this mechanism is investigated performing numerical experiments of thick penumbral tubes in mechanical equilibrium with a background field. Conclusions: While the one-component inversions confirm many of the properties indicated by a simple line parameter analysis (Paper I of this series), we tend to give more credit to the results of the uncombed inversions because they take into account, at least in an approximate manner, the fine structure of the penumbra.Comment: Accepted for publication in A&

The properties of penumbral microjets inclination

We investigate the dependence of penumbral microjets inclination on the position within penumbra. The high cadence observations taken on 10 November 2006 with the Hinode satellite through the \ion{Ca}{ii} H and G--band filters were analysed to determine the inclination of penumbral microjets. The results were then compared with the inclination of the magnetic field determined through the inversion of the spectropolarimetric observations of the same region. The penumbral microjet inclination is increasing towards the outer edge of the penumbra. The results suggest that the penumbral microjet follows the opening magnetic field lines of a vertical flux tube that creates the sunspot.Comment: 4 pages, 4 figures, A&A Letter in pres

Electronic pressure on ferromagnetic domain wall

The scattering of the eletron by a domain wall in a nano-wire is studied perturbatively to the lowest order. The correction to the thermodaynamic potential of the electron system due to the scattering is calculated from the phase shift. The wall profile is determined by taking account of this correction, and the result indicates that the wall in a ferromagnet with small exchange coupling can be squeezed to be very thin to lower the electron energy

COMalaWEB: plataforma basada en noves tecnologies aplicades a la docència

Les possibilitats que ens ofereixen les noves tecnologies de la informació aplicades a l’àmbit de la docència és un tema encara no prou ben explotat. Aquest projecte pretén investigar aquests conceptes mitjançant la creació d’una plataforma docent que aprofita la potencialitat de tecnologies tals com les bases de dades, l’estructuració de documents en XML, l’hipertext o la representació gràfica interactiva. A més, aquesta estructura s’ha farcit amb continguts docents de qualitat que cobreixen el temari de dues assignatures obligatòries al programa d’Enginyeria Superior de Telecomunicacions de la UPC. El procés d’aprenentatge es basa en la integració de petits conceptes sobre una base ja coneguda. La rigidesa d’un temari fix, o l’índex d’un llibre, forcen un seguiment lineal dels conceptes que sovint no és l’òptim ni per al professor ni per a l’alumne. COMalaWEB permet la consulta de diferents conceptes de forma no lineal, on l’usuari decideix quin nivell d’aprofundiment necessita, si vol més exemples, retornar a conceptes anteriors o anar a temes més avançats. Aquestes capacitats es complementen amb aplicacions d’autoavaluació i demostracions gràfiques interactives que reforcen la realimentació entre teoria i pràctica. La totalitat del programari desenvolupat per a la implementació d’aquesta plataforma i els continguts docents que presenta han estat publicats sota llicència pública per assegurar-ne la lliure distribució i accés, així com la protecció dels drets intel•lectuals