1,065 research outputs found

    On the nature of some SGRs and AXPs as rotation-powered neutron stars

    Full text link
    We investigate the possibility that some SGRs/AXPs could be canonical rotation-powered pulsars using realistic NS structure parameters instead of fiducial values. We show that realistic NS parameters lowers the estimated value of the magnetic field and radiation efficiency, LX/E˙rotL_X/\dot{E}_{\rm rot}, with respect to estimates based on fiducial NS parameters. We show that nine SGRs/AXPs can be described as canonical pulsars driven by the NS rotational energy, for LXL_X computed in the soft (2--10~keV) X-ray band. We compute the range of NS masses for which LX/E˙rot<1L_X/\dot{E}_{\rm rot}<1. We discuss the observed hard X-ray emission in three sources of the group of nine potentially rotation-powered NSs. This additional hard X-ray component dominates over the soft one leading to LX/E˙rot>1L_X/\dot{E}_{\rm rot}>1 in two of them. We show that 9 SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in the soft 2--10~keV band. Interestingly, four of them show radio emission and six have been associated with supernova remnants (including Swift J1834.9-0846 the first SGR observed with a surrounding wind nebula). These observations give additional support to our results of a natural explanation of these sources in terms of ordinary pulsars. Including the hard X-ray emission observed in three sources of the group of potential rotation-powered NSs, this number of sources with LX/E˙rot<1L_X/\dot{E}_{\rm rot}<1 becomes seven. It remains open to verification 1) the accuracy of the estimated distances and 2) the possible contribution of the associated supernova remnants to the hard X-ray emission.Comment: 11 pages, 14 figures, to appear in A&

    Una aproximación sintaxonómica sobre la vegetación del Perú: clases, órdenes y alianzas

    Get PDF
    Una aproximación sintaxonómica sobre la vegetación del Perú. Clases, órdenes y alianzas. En el presente trabajo damos a conocer una primera aproximación al esquema sintaxonómico de la vegetación peruana hasta el nivel de alianza. Se describen dos nuevas clases (Nicotiano-Ambrosietea y Mayacetea fluviatilis), 12 órdenes (Adiantetalia raddiani, Alnetalia, Cestro-Prunetalia, Commelinetalia, Cryptocarpo-Prosopidetalia, Mutisio-Baccharidetalia, Nicotianetalia, Oryzo-Hymenachnetalia, Polylepidetalia racemosae, Polypodio-Puyetalia, Salicetalia caroliniano-humboldtianae y Saxifragetalia magellanicae), 14 alianzas (Adiantion subvolubilis, Aristido-Chloridion, Bursero-Prosopidion, Espostoo-Neoraimondion, Loasion, Mutisio-Ophryosporidion, Myrcianthion quinquelobae, Myrico-Alnion, Peperomio-Puyion, Ribesido-Polylepidion, Saxifragion magellanicae, Sicyo-Urticion, Siegesbeckio-Commelinion y Tecomion arequipensis) y 10 asociaciones (Adiantetum subvolubilis, Barnadesio-Ophryosporidetum, Cercidio-Prosopidetum, Haageocereo-Neoraimondietum, Peperomio-Tillandsietum, Philoglosso-Urocarpidetum, Schino-Acacietum, Tristerido-Myrcianthetum, Valeriano-Saxifragetum y Valleo-Alnetum). Además se establece un estado nuevo (Chusqueetalia tessellatae stat. nov.) que permite sistematizar los matorrales andinos con bambusoideas ("chuscales")

    Infraestructura de datos espaciales en medio ambiente y acceso a la información ambiental en Andalucía. El canal de la red de información ambiental de Andalucía.

    Get PDF
    La Consejería de Medio Ambiente de la Junta de Andalucía ha puesto en marcha un sistema para poder cumplir adecuadamente los requisitos derivados de la normativa vigente en dos vertientes que están muy relacionadas: la del acceso a la información ambiental y la de las Infraestructuras de Datos Espaciales. Ambas vertientes, que vienen definidas por sendas Directivas, han condicionado la solución establecida que pasa por la creación mediante el desarrollo normativo adecuado de un instrumento, la Red de Información Ambiental de Andalucía (REDIAM). Esta red se ha dotado de una plataforma en entorno web, el Canal de la Red de Información Ambiental de Andalucía, en la que confluyen elementos constitutivos de una Infraestructura de Datos Espaciales (IDE) con otros de obtención y acceso al dato como es el de de solicitud de información ambiental o la descarga directa, y con elementos de navegación que pretenden facilitar al público en general el acceso a este conjunto de servicios y productos. Puesto en explotación el 29 de enero de 2009, hoy podemos hacer balance del uso que ha registrado en su primer año.The Ministry of Environment of the Junta de Andalucía has launched a system to carry out the requirements under current regulations in two areas which are closely related: access to environmental information and Spatial Data Infrastructures. Both sides, which are defined by EU Directives, have conditioned the solution through the developing an appropriate regulatory instrument, the Environmental Information Network of Andalusia (REDIAM). This network has set up a web-based platform, the Andalusian Environmental Information Network Channel, which combines elements of a Spatial Data Infrastructure (SDI) with other elements of data collection and access like the environmental information request or direct download, and navigation elements that are intended to facilitate the general public access to the package of services and products. Having been put into operation on January 29, 2009, today we can assess the use it has registered in its first year

    Mapa guía digital del espacio natural de Doñana: un sistema de difusión y acceso a la información técnica de la Rediam

    Get PDF
    Dentro de la línea de difusión de información ambiental que imponen directrices europeas, leyes estatales y autonómicas, se ha planteado dar un giro a la clásica producción de los mapas guía de los espacios naturales de Andalucía. Esta nació con el Mapa Guía de Doñana en el año 1989 y ha venido y viene renovándose desde entonces con nuevas versiones. A lo largo de este tiempo, la tecnología y la información disponible han cambiado notablemente, y con objeto de facilitar a los ciudadanos el manejo de la información cartográfica existente de los diferentes Espacios Naturales, se crea un nuevo concepto denominado “Mapas Guía Digitales de Espacios Naturales”. El mapa guía digital de Doñana, se presenta como una amplia guía en formato “libro-disco”, aunando la proximidad de un texto amenizado con fotografías, con una potente herramienta informática que facilita análisis cartográficos, o recorridos virtuales. El texto permite conocer Doñana desde la perspectiva ambiental, y la aplicación informática, a una completa información sobre vegetación, equipamientos, ecosistemas, historia y tradiciones, además de imágenes satélite, ortofotos y fotografías. Por su especial relevancia, la AVIFAUNA ha sido tratada de forma especial integrando en la aplicación una completa guía de campo.In-line dissemination of environmental information that impose European guidelines, state and regional, has been raised to turn the classic guide to production of maps of natural areas of Andalusia.This was created with the Map Guide Doñana in 1989 and has been renewed and comes with new versions since then. Throughout this time, technology and information available have changed dramatically, and in order to provide citizens with the management of topographic data available from different natural areas, establishing a new concept called "Digital Guide Maps of Natural Spaces”. The digital guide map of Doñana, is presented as a comprehensive guide format "book-album", combining the proximity of a text enlivened with photographs, with a powerful analysis tool that facilitates mapping or virtual tours. The text allows Doñana know from an environmental perspective, and computer application, to complete information about vegetation, equipment, ecosystems, history and traditions, in addition to satellite imagery, orthophotos and photographs. Because of its special relevance, BIRDS has been specially treated in the implementation integrating a complete field guide

    The Period-Luminosity Relation of RR Lyrae Stars in the SDSS Photometric System

    Full text link
    We provide the first detailed study of the RR Lyrae period-luminosity (PL) relation in the ugriz bandpasses of the Sloan Digital Sky Survey (SDSS) filter system. We argue that tight, simple PL relations are not present in the SDSS filters, except for the redder bandpasses i and (especially) z. However, for all bandpasses, we show that, by incorporating terms involving a (fairly reddening-independent) "pseudo-color" C_0 = (u-g)_0 - (g-r)_0, tight (non-linear) relations do obtain. We provide theoretically calibrated such relations in the present paper, which should be useful to derive precise absolute magnitudes (hence distances) and intrinsic colors (hence reddening values) to even {\em individual} field RR Lyrae stars. For applications to cases where photometry in all five passbands may not be available, we also provide simple (though less precise) average PL relations for the i and z bandpasses, which read as follows: M_z = 0.839 - 1.295 log P + 0.211 log Z, M_i = 0.908 - 1.035 log P + 0.220 log Z. Similarly, simple period-color relations for (r-i)_0, (g-r)_0, and (u-z)_0 are also provided.Comment: 7 pages, 9 figures. ApJS, in pres

    Una aproximación sintaxonómica sobre la vegetación del Perú. Clases, órdenes y alianzas

    Get PDF
    RESUMEN. Una aproximación sintaxonómica sobre la vegetación del Perú. Clases, órdenes y alianzas. En el presente trabajo damos a conocer una primera aproximación al esquema sintaxonómico de la vegetación peruana hasta el nivel de alianza. Se describen dos nuevas clases (Nicotiano- Ambrosietea y Mayaceteaf luviatilis), 12 órdenes (Adiantetalia raddiani, Alnetalia, Cestro-Prunetalia, Commelinetalia, Cryptocarpo-Prosopidetalia, Mutisio-Baccharidetalia, Nicotianetalia, Oryzo- Hymenachnetalia, Polylepidetalia racemosae, Polypodio-Puyetalia, Salicetalia caroliniano- humbolchianae ySaxifragetalia magellanicae), 14 alianzas (Adiantion subvolubilis, Aristido-Chloridion, Bursero-Prosopidion, Espostoo-Neoraimondion, Loasion, Mutisio-Ophryosporidion, Myrcianthion quinquelobae, Myrico-Alnion, Peperomio-Puyion, Ribesido-Polylepidion, Saxifragion magellanicae, Sicyo-Urficion„Siegesbeckio-Commelinion y Tecomion arequipensis) y 10 asociaciones (Adiantetum subvolubilis, Bartiadesio-Ophryosporidetum, Cercidio-Prosopidetum, Haageocereo-Neoraimondietum, Peperomio-Tillculdsietum, Philoglosso-Uroccopidetum,Schino-Acacietum,Tristerido-Myrcianthetum, Valeriano-Saxifragetum y Valleo-Alnetutn). Además se establece un estado nuevo (Chusqueetalia tessellatae stat.nov.)que permite sistematizar los matorrales andinos con bambusoideas ("chuscales").Palabras clave. Vegetación, Fitosociología, Sintaxonomfa, Perú.ABSTRACT. A syntaxonomic approximation about the vegetation of Peru. Classes, orders and alliances. In this paper, a first syntaxonomic approximation to the syntaxonomic scheme of the Peruvian vegetation down to the alliance level is presented. Two new classes (Nicoticmo-Ambrosietea and Mayacetea f hiviatilis), 12 orders (Adiantetalia raddiani, Alnetalia, Cestro-Prunetalia, Commelinetalia, Cryptocarpo-Prosopidetalia, Mutisio-Baccharidetalia, Nicotianetalia, Oryzo- Hymenachnetalia, Polylepidetalia racemosae, Polypodio-Puyetalia, Salicetalia caroliniano- humboldnanae and Saxifragetalia magellanicae), 14 alliances (Adicional subvolubilis, Aristido- Chloridion, Bursero-Prosopidion, Espostoo-Neoraimondion, Loasion, Munsio-Ophryosporidion, Myrciamhion quinquelobae, Myrico-Alnion, Peperomio-Puyion, Ribesido-Polylepidion, Saxifragion magellanicae, Sicyo-Urticion„Siegesbeckio-Commelinion and Tecomion arequipensis) and 10 associations (Adiametum subvolubilis, Bartiadesio-Ophryosporidetum, Cercidio-Prosopidetum, Haageocereo-Neoraimondietum, Peperomio-Tillandsiencm, Philoglosso-Urocarpidetutn, Schino- Acacietum, Tristerido-Myrcianthetum, Valeriano-Saxifragetunt and Valleo-Alnetum) are described. Also, a new status is stablished (Chusqueetalia tessellatae stat. nov. ) to systematize the Andean bamboo-scrubs ("chuscales").Key words. Vegetation, Phytosociology, Syntaxonomy, Peru

    SIOSE Andalucía, experiencia de integración y actualización de bases cartográficas multiescala

    Get PDF
    El objetivo de SIOSE en Andalucía ha sido la obtención de una base cartográfica de referencia a escala de detalle 1:10.000, escalable a 1:25.000, donde se sintetizan e integran tanto la información geométrica como la temática de cartografías ya existentes (usos del territorio, SIGPAC, coberturas del suelo, información de comunidades fitosociológicas, redes de comunicación, superficies húmedas, red hidrográfica, zonas de extracción, balsas, entramado urbano, etc.) siguiendo un protocolo establecido para, posteriormente, actualizarla al año de referencia mediante fotointerpretación. La integración de las diferentes cartografías se fundamentó en la definición de unos valores mínimos de tolerancia, tanto de distancia entre líneas como de tamaño mínimo de superficie en función del uso asignado al polígono. La generación de la cartografía a escala 1:25.000 se llevó a cabo a través de procesos automáticos de cambio de modelo de datos, cambio de escala y eliminación de pasillos. La inquietud de abordar la experiencia de SIOSE-Andalucía nace de la necesidad detectada desde hace tiempo de tener una base de referencia que combine parámetros bióticos con elementos administrativos y el parcelario de la propiedad.The aim of SIOSE in Andalucía has been obtaining a detailed scale 1:10.000 cartographic database of reference, scalable to 1:25.000, where geometry and also thematic information of existing cartographies have been combined and joined (land uses, SIGPAC, land covers, phytosociological plant communities, communication network, humid areas, hydrographic network, extraction zones, irrigation pools, urban network, etc.) following an established protocol for, afterwards, updating the cartography to the referred year using photo-interpretation. The integration of different cartographies is based on the definition of minimum values of tolerance for the distance between lines as well as minimum sizes of area, depending on the assigned land use to each polygon. The production of cartography 1:25.000 was carried out through automatic processes of data model converter, scale change and elimination of narrowing polygons. The interest of tackling the experience of SIOSE-Andalucia is sprung from the detected necessity of having a resource which combines biotic parameters with administrative elements and property divisions

    Real-time static potential in hot QCD

    Full text link
    We derive a static potential for a heavy quark-antiquark pair propagating in Minkowski time at finite temperature, by defining a suitable gauge-invariant Green's function and computing it to first non-trivial order in Hard Thermal Loop resummed perturbation theory. The resulting Debye-screened potential could be used in models that attempt to describe the ``melting'' of heavy quarkonium at high temperatures. We show, in particular, that the potential develops an imaginary part, implying that thermal effects generate a finite width for the quarkonium peak in the dilepton production rate. For quarkonium with a very heavy constituent mass M, the width can be ignored for T \lsim g^2 M/12\pi, where g^2 is the strong gauge coupling; for a physical case like bottomonium, it could become important at temperatures as low as 250 MeV. Finally, we point out that the physics related to the finite width originates from the Landau-damping of low-frequency gauge fields, and could be studied non-perturbatively by making use of the classical approximation.Comment: 20 pages. v2: a number of clarifications and a few references added; published versio

    Ordering and finite-size effects in the dynamics of one-dimensional transient patterns

    Full text link
    We introduce and analyze a general one-dimensional model for the description of transient patterns which occur in the evolution between two spatially homogeneous states. This phenomenon occurs, for example, during the Freedericksz transition in nematic liquid crystals.The dynamics leads to the emergence of finite domains which are locally periodic and independent of each other. This picture is substantiated by a finite-size scaling law for the structure factor. The mechanism of evolution towards the final homogeneous state is by local roll destruction and associated reduction of local wavenumber. The scaling law breaks down for systems of size comparable to the size of the locally periodic domains. For systems of this size or smaller, an apparent nonlinear selection of a global wavelength holds, giving rise to long lived periodic configurations which do not occur for large systems. We also make explicit the unsuitability of a description of transient pattern dynamics in terms of a few Fourier mode amplitudes, even for small systems with a few linearly unstable modes.Comment: 18 pages (REVTEX) + 10 postscript figures appende
    corecore