Metallic slabs: Perturbative treatments based on jellium

We examine first-order perturbative results based on jellium for the surface energy of slabs of simple metals, using various local pseudopotentials (Ashcroft, Heine-Abarenkov and evanescent core). The difference between the pseudopotential and the jellium potential is averaged along the plane parallel to the surface. We compare these perturbative results with those of the stabilized jellium model (a modification of the regular jellium model in which the perturbation appears in the energy functional right from the outset) and with the output of other perturbative and non-perturbative calculations.Comment: 15 pages, 2 figures, to appear in Prog. Surf. Sc

Classification of Landsat 8 images in the Segura Hydrographic Demarcation

[EN] This work presents a cartography of land uses in the Segura Hydrographic Demarcation obtained by classifying 2017 Landsat 8 images. The classification was carried out using two classifiers: Maximum Likelihood (ML) and Random Forest (RF). Training areas were obtained from historical high resolution imagery until 2016. Prior to classification, a cross validation analysis of the training areas was carried out to determine which of them may have undergone a change of use between 2016 and 2017. The results obtained with ML and RF, both with the original set of training areas and with the one obtained eliminating the problem, are compared to determine the best option. In the case of ML, the results improve after eliminating the changing training areas, from 77.7% to 81.4%; however, with RF this improvement is not so important, going from 84.1% to 85.1%. Therefore, it can be concluded that, with both methods, the classification is more exact when the modified training areas are used and, although the results obtained are quite acceptable for both ML and RF, the latter performs a more accurate classification.[ES] En el presente trabajo se obtiene, a través de un proceso de clasificación digital de imágenes Landsat 8 de 2017, una cartografía de usos del suelo en la Demarcación Hidrográfica del Segura; la clasificación se ha llevado a cabo empleando dos clasificadores: Máxima Verosimilitud (MV) y Random Forest (RF). Puesto que las áreas de entrenamiento se obtienen de imágenes históricas de alta resolución hasta 2016, previamente a la clasificación, se hace un análisis de validación cruzada de las áreas de entrenamiento para determinar cuáles de ellas pueden haber sufrido un cambio de uso entre 2016 y 2017. Los resultados obtenidos con MV y con RF, tanto con el conjunto original de áreas como con el obtenido eliminando la problemática, se comparan para determinar cuál es la mejor opción. En el caso de MV mejoran notablemente los resultados cuando se realiza la depuración de las áreas de entrenamiento, pasando de un porcentaje de acierto del 81% al 84,9%; sin embargo, con RF esta mejora no es tan importante ya que se pasa del 84,1% al 85,1%. Por tanto, se puede concluir que, con ambos métodos la clasificación es más exacta cuando se emplean las áreas de entrenamiento depuradas y, aunque los resultados obtenidos son bastante aceptables tanto para MV como para RF, este último realiza una clasificación más exacta.Rodríguez-Valero, MI.; Alonso-Sarria, F. (2019). Classification of Landsat 8 images in the Segura Hydrographic DemarcationClasificación de imágenes Landsat-8 en la Demarcación Hidrográfica del Segura. Revista de Teledetección. (53):33-44. https://doi.org/10.4995/raet.2019.11016SWORD33445

Duodenal metastasis of alveolar soft part sarcoma

Aveolar soft part sarcoma is a rare tumor responsible for about 1% of all soft tissue sarcomas, affecting mostly adolescents and young adults. ASPS has curious patterns of metastatic spread, with seldom lymph node involvement. Lung, bone and brain are the most common metastatic places. Small bowel metastasis are infrequent, having found reported only one case of duodenal metastasis with polypous appearance. We describe a case of duodenal metastasis presenting as abdominal mass five years after initial diagnosis of alveolar soft part sarcoma

Preferential oxidation of CO (CO-PROX) over CuOx/CeO2 coated microchannel reactor

The general aspects of the synthesis and characterization results of a CuOx/CeO2 catalyst were presented. In addition the principal steps for manufacturing a microchannel reactor and for the coating of the CuOx/CeO2 catalyst onto the microchannels walls, were also summarized. The catalytic activity of this microchannel reactor during the preferential oxidation of CO (CO-PROX) was evaluated employing a feed-stream that simulates a reformate off-gas after the WGS unit. Two activation atmospheres were studied (H2/N2 and O2/N 2). The reducing pretreatment improved the resistance to deactivation by formation of carbonaceous species over the catalyst surface at high temperatures. The presence of H2O and CO2 in the feed-stream was also analyzed indicating that the adsorption of CO2 inhibited the conversion of CO at lower temperatures because these compounds modified the active sites through the formation of carbonaceous species on the catalyst surface. Finally, the experimental results of the microreactor performance were compared with CFD simulations that were carried out using a kinetic for the CuOx/CeO2 powder catalyst. The experimental results were reasonably well described by the model, thus confirming its validity.Peer Reviewe

Aprendiendo a educar para la salud a través del aprendizaje servicio. Compartir ideas, la universidad va al instituto

Se parte de un proyecto de aprendizaje servicio transversal de desarrollo de un ciclo de conferencias taller a estudiantes de secundaria realizadas por estudiantes de la UB. Por parte del grado en enfermería se proponen conferencias relacionadas con el cuidar y la educación para la salud. Los objetivos son compartir conocimientos entre estudiantes universitarios y de secundaria sobre temas de interés mutuo para su formación; adquirir habilidades en educación para la salud y trabajo en equipo

Objetos cotidianos y escultura sin taller: una experiencia educativa artística adaptada a las restricciones de la pandemia de Covid-19

Durante los primeros días del confinamiento domiciliario, las universidades no disponían aún de las herramientas necesarias para implementar el nuevo modelo de clases online. Este artículo relata una experiencia de adaptación a contrarreloj, para continuar con las tareas lectivas de la asignatura 'Taller de Creación II' del Grado de Bellas Artes (UB): se propuso a los alumnos/as una serie de ejercicios prácticos utilizando recursos cotidianos como solución de emergencia para crear obras de arte

Slabs of stabilized jellium: Quantum-size and self-compression effects

We examine thin films of two simple metals (aluminum and lithium) in the stabilized jellium model, a modification of the regular jellium model in which a constant potential is added inside the metal to stabilize the system for a given background density. We investigate quantum-size effects on the surface energy and the work function. For a given film thickness we also evaluate the density yielding energy stability, which is found to be slightly higher than the equilibrium density of the bulk system and to approach this value in the limit of thick slabs. A comparison of our self-consistent calculations with the predictions of the liquid-drop model shows the validity of this model.Comment: 7 pages, 6 figures, to appear in Phys. Rev.