1,035 research outputs found

    Warp evidences in precessing galactic bar models

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    Most galaxies have a warped shape when they are seen from an edge-on point of view. The reason for this curious form is not completely known so far and in this work we apply dynamical system tools to contribute to its explanation. Starting from a simple, but realistic, model formed by a bar and a disc, we study the effect produced by a small misalignment between the angular momentum of the system and its angular velocity. To this end, a precession model is developed and considered, assuming that the bar behaves like a rigid body. After checking that the periodic orbits inside the bar keep being the skeleton of the inner system, even after inflicting a precession to the potential, we compute the invariant manifolds of the unstable periodic orbits departing from the equilibrium points at the ends of the bar to get evidences of their warped shapes. As it is well known, the invariant manifolds associated with these periodic orbits drive the arms and rings of barred galaxies and constitute the skeleton of these building blocks. Looking at them from a side-on viewpoint, we find that these manifolds present warped shapes as those recognized in observations. Lastly, test particle simulations have been performed to determine how the stars are affected by the applied precession, confirming this way the theoretical results obtained.Comment: 14 pages, 21 figures, Accepted for publication in A&A (15th Jan 2016

    Sistema de medida de biopotenciales para plantas y árboles con PSoC

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    Este proyecto presenta el desarrollo de un nuevo sistema automatico para la medicion de biopotenciales en plantas e incluso en arboles. La base del sistema la constituye una placa de evaluacion (PSoC1 EVALUATION KIT) del sistema reconfigurable CY8C29466 fabricado por Cypress Semiconductor Corp. El sistema permite la conexion de una planta o arbol al PSoC para medir sus biopotenciales y, a continuacion, tratar la adquisicion de datos, procesarlos y enviarlos al ordenador mediante el puerto serie RS232. Mediante la interfaz LabVIEW?, sera posible visualizar los datos en tiempo real o los datos medidos y almacenados en la memoria EEPROM del propio PSoC. Ademas, sera posible efectuar registros rapidos para estudiar la respuesta instantanea ante estimulos externos o registros lentos para estudiar procesos fisiologicos relacionados con el ciclo dia-noche durante algunos dias. El uso del PSoC permitira minimizar el tama?o de todo el sistema y al mismo tiempo, ofrecer las prestaciones necesarias para la implementacion del sistema de medida de biopotenciales, asi como tambien, la posibilidad de tener un sistema de medicion autonomo, sin necesidad de componentes adicionales

    Efficient dynamic simulation of pH in processes associated to biofiltration of volatile inorganic pollutants

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    This work proposes a generic methodology to include the pH as a state variable in mathematical models of bioreactors. An ordinary differential equation for pH is stated and introduced into the general model structure of a biotrickling filter. All chemical equilibriums were considered and included into the model framework. A preliminary evaluation was performed by comparing results predicted by the model with experimental data obtained from the oxidation of thiosulfate by sulfide-oxidizing bacteria under alkaline conditions. The model was able to describe adequately the evolution of the main state variables including the pH for the initial complete oxidation of thiosulfate. The methodology presented here can be easily adapted to other mathematical models dealing with biological waste treatment processes in which pH appears as a key factor.Postprint (published version

    Thermal Jeans fragmentation within 1000 AU in OMC-1S

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    We present subarcsecond 1.3 mm continuum ALMA observations towards the Orion Molecular Cloud 1 South (OMC-1S) region, down to a spatial resolution of 74 AU, which reveal a total of 31 continuum sources. We also present subarcsecond 7 mm continuum VLA observations of the same region, which allow to further study fragmentation down to a spatial resolution of 40 AU. By applying a Mean Surface Density of Companions method we find a characteristic spatial scale at ~560 AU, and we use this spatial scale to define the boundary of 19 `cores' in OMC-1S as groupings of millimeter sources. We find an additional characteristic spatial scale at ~2900 AU, which is the typical scale of the filaments in OMC-1S, suggesting a two-level fragmentation process. We measured the fragmentation level within each core and find a higher fragmentation towards the southern filament. In addition, the cores of the southern filament are also the densest (within 1100 AU) cores in OMC-1S. This is fully consistent with previous studies of fragmentation at spatial scales one order of magnitude larger, and suggests that fragmentation down to 40 AU seems to be governed by thermal Jeans processes in OMC-1S.Comment: Accepted to Ap

    Increasing Cervical Cancer Screening Coverage: A Randomised, Community-based Clinical Trial

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    Background: Opportunistic cervical cancer screening can lead to suboptimal screening coverage. Coverage could be increased after a personalised invitation to the target population. We present a community randomized intervention study with three strategies aiming to increase screening coverage. Methods: The CRICERVA study is a community-based clinical trial to improve coverage of population-based screening in the Cerdanyola SAP area in Barcelona. A total of 32,858 women residing in the study area, aged 30 to 70 years were evaluated. A total of 15,965 women were identified as having no registration of a cervical cytology in the last 3.5 years within the Public Health data base system. Eligible women were assigned to one of four community randomized intervention groups (IGs): (1) (IG1 N = 4197) personalised invitation letter, (2) (IG2 N = 3601) personalised invitation letter + informative leaflet, (3) (IG3 N = 6088) personalised invitation letter + informative leaflet + personalised phone call and (4) (Control N = 2079) based on spontaneous demand of cervical cancer screening as officially recommended. To evaluate screening coverage, we used heterogeneity tests to compare impact of the interventions and mixed logistic regression models to assess the age effect. We refer a "rescue" visit as the screening visit resulting from the study invitation. Results: Among the 13,886 women in the IGs, 2,862 were evaluated as having an adequate screening history after the initial contact; 4,263 were lost to follow-up and 5,341 were identified as having insufficient screening and thus being eligible for a rescue visit. All intervention strategies significantly increased participation to screening compared to the control group. Coverage after the intervention reached 84.1% while the control group reached 64.8%. The final impact of our study was an increase of 20% in the three IGs and of 9% in the control group (p<0.001). Within the intervention arms, age was an important determinant of rescue visits showing a statistical interaction with the coverage attained in the IGs. Within the intervention groups, final screening coverage was significantly higher in IG3 (84.4%) (p< 0.001). However, the differences were more substantial in the age groups 50-59 and those 60+. The highest impact of the IG3 intervention was observed among women 60+ y.o with 32.0% of them being rescued for screening. The lowest impact of the interventions was in younger women. Conclusions: The study confirms that using individual contact methods and assigning a fixed screening date notably increases participation in screening. The response to the invitation is strongly dependent on age

    New Approaches in Tourism Management: The Innovative Business Group Programme in Spain

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    Este estudio se enmarca en el análisis de las nuevas políticas de innovación aplicadas al turismo en España. El objetivo fundamental es evaluar la política reciente de apoyo a la creación y consolidación de Agrupaciones Empresariales Innovadoras en el ámbito del turismo, el Programa AEIs, atendiendo a su singularidad, las características de las AEIs resultantes y la valoración de sus responsables. El análisis ofrece luces y sombras y concluye con argumentos para repensar este tipo de políticas, así como con elementos de discusión interesantes en torno a la innovación derivada de los procesos de colaboración en turismo.This study aims to evaluate recent tourism innovation policies in Spain, specifically those that support the creation and consolidation of the Innovative Business Group (AEI, for its initials in Spanish) Programme in Tourism, its singularity, the characteristics of the resulting AEIs and the evaluation made by managers. The analysis shows the lights and shadows of the Programme and also suggests the need to reformulate these types of policies. It also highlights interesting discussion points about the innovation derived from collaborative processes in tourism.El presente trabajo se enmarca en el proyecto de investigación «Metodología, criterios y aplicaciones para la configuración de clusters en áreas turísticas consolidadas: innovación, complementariedad y competitividad territorial» (CSO2011-26396), financiado por el Plan Nacional de I+D+i del Ministerio de Economía y Competitividad

    Nubosidad y radiación solar en la Península Ibérica entre 1950 y 2050. De las evidencias observacionales a las simulaciones climáticas

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    En este trabajo se presenta una revisión de diversos estudios que describen la evolución de la nubosidad y la radiación solar en superficie en la Península Ibérica desde mediados del siglo XX. Estos estudios se basan mayoritariamente en las observaciones recogidas en las estaciones meteorológicas de superficie, pero para el período más reciente, se utilizan también datos de satélite y de reanálisis. Los estudios revisados muestran una buena coherencia entre ellos, destacando en las series de insolación el fenómeno del dimming (1955-1985 aprox.) seguido del brightening (1985-2010 aprox.); mientras que la nubosidad muestra un descenso continuo desde los años 1960 a la actualidad, lo que lleva a pensar en un efecto no despreciable de los aerosoles atmosféricos. Presentamos también las proyecciones futuras de la nubosidad total, a partir de los resultados de los modelos globales del CMIP5. Las proyecciones muestran un progresivo descenso de la nubosidad que debería provocar un aumento de la radiación solar durante los próximos decenios.This paper presents a review of several published studies that describe the evolution of cloud cover and surface solar radiation in the Iberian Peninsula since the mid-twentieth century. These studies are based mainly on ground observations taken at meteorological stations, but for the most recent period satellite data and reanalysis data have also been used. The reviewed studies show good consistency between them. The phenomenon of dimming (1955-1985 approx.) followed by brightening (1985-2010 approx.) is clearly detected in sunshine duration series. In cloudiness series, we observe a continuous decline of total cloud cover from the 1960s until today, which suggests a non-negligible effect of atmospheric aerosols. We also present future projections of total cloudiness, based on results of global climate models included in CMIP5. Projections show a progressive decrease in cloudiness which should drive increased solar radiation during the coming decades.El conjunto de trabajos revisados en el presente artículo se ha llevado a cabo en el marco de proyectos financiados por el Ministerio responsable de políticas de investigación. Actualmente, la investigación del grupo viene financiada por el proyecto NUBESOL (CGL2014-55976-R). El quinto autor disfruta de una beca Juan de la Cierva
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