1,042 research outputs found

    Non-equilibrium transition from dissipative quantum walk to classical random walk

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    We have investigated the time-evolution of a free particle in interaction with a phonon thermal bath, using the tight-binding approach. A dissipative quantum walk can be defined and many important non-equilibrium decoherence properties can be investigated analytically. The non-equilibrium statistics of a pure initial state have been studied. Our theoretical results indicate that the evolving wave-packet shows the suppression of Anderson's boundaries (ballistic peaks) by the presence of dissipation. Many important relaxation properties can be studied quantitatively, such as von Neumann's entropy and quantum purity. In addition, we have studied Wigner's function. The time-dependent behavior of the quantum entanglement between a free particle -in the lattice- and the phonon bath has been characterized analytically. This result strongly suggests the non-trivial time-dependence of the off-diagonal elements of the reduced density matrix of the system. We have established a connection between the quantum decoherence and the dissipative parameter arising from interaction with the phonon bath. The time-dependent behavior of quantum correlations has also been pointed out, showing continuous transition from quantum random walk to classical random walk, when dissipation increases.Comment: Submitted for publication. 17 pages, 6 figure

    Histological and histochemical study of the digestive system of Argopecten ventricosus (Sowerby, 1842)

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    Histological and histochemical studies on the digestive system of Argopecten ventricosus (Sowerby, 1842) was carried out. Lips show a ciliated columnar epithelium with glycoproteins and acid and alkaline phosphatases, and α-D glucosidase activity. Esophagus and lips epitheliums are similar. Acid and alkaline phosphatases, α-D glucosidase and leucil aminopeptidase activities were detected. The epithelium of the stomach is ciliated and contains glands which secrete glycoproteins. Acid and alkaline phosphatases, α-D glucosidase, leucil aminopeptidase and amylase activities were found. The digestive gland is tubular, and several activities were detected in the tubules.Se han realizado estudios histológicos e histoquímicos del sistema digestivo de Argopecten ventricosus (Sowerby, 1842). En los palpos labiales se observó un epitelio densamente ciliado, con mucopolisacáridos, que reveló reacción positiva para fosfatasas alcalinas, ácidas y α-D glucosidasa. En el esófago se advertía un epitelio cilíndrico ciliado con actividad fosfatasas ácidas y alcalinas, α-D glucosidasa y leucil aminopeptidasa. El epitelio estomacal es ciliado y contiene células secretoras de mucopolisacáridos ácidos. En este órgano se detectó actividad para fosfatasas ácidas y alcalinas, α-D glucosidasa, leucil aminopeptidasa y amilasa. La glándula digestiva presentaba un arreglo túbulo-acinar con células en estadios diferentes. Se reveló actividad para fosfatasas alcalinas, α-D glucosidasa, N-acetil-β glucosaminidasa y leucil aminopeptidasa. El intestino mostraba un epitelio de tipo columnar ciliado con células secretoras intercaladas.Instituto Español de Oceanografí

    FAME. Aplicación web de apoyo al seguimiento, localización e integración de la información sobre flora amenazada y de interés generada en Andalucía

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    FAME es un sistema de información geográfica, integrado en la Red de Información Ambiental de Andalucía (REDIAM), de apoyo a la localización y seguimiento de la Flora Amenazada y de Interés de Andalucía, el cual centraliza la información que generan los distintos proyectos de la temática en el repositorio único de la Consejería de Medio Ambiente (CMA). Utilizando nuevas tecnologías se ha creado una herramienta Web que gestiona el recorrido completo de la información de Flora Amenazada, desde el levantamiento de la información, con el apoyo de una aplicación PDA, y la incorporación y edición de datos temáticos y gráficos, por medio de un visor cartográfico, hasta el proceso de validación temático para evitar errores en la incorporación de la información. En este proyecto se utiliza una arquitectura basada en la tecnología del software libre, destacando el visor geográfico desarrollado sobre OpenLayers, la aplicación para PDA desarrollada sobre el núcleo de Enebro y el uso de estándares OGC, tanto para la utilización de cartografía base mediante WMS, como para el acceso y la edición vía web a través de WFS-T. Este proyecto es una apuesta de la CMA por el uso del software libre como elemento principal en desarrollos complejosFAME is a geographic information system, integrated in the Andalusian Environmental Information Net (REDIAM), to support the location and tracking of Threatened and Interesting Flora of Andalusia, which centralizes the information generated in the different projects related with the thematic in the Unique Data Reservoir of Andalusian Environmental Council (CMA). A Web tool has been created using new technology which manages the complete Threatened Flora information layout, from the information gathering,, with the support of a PDA application, the incorporation and thematic data and graphic edition, using a cartographic viewer, to the thematic validation process to avoid mistakes in the information incorporation. This project uses an architecture based on free software technology, in Tecnologías de la Información Geográfica: la Información Geográfica al Servicio de los Ciudadanos. Secretariado de Publicaciones de la Universidad de Sevilla. Sevilla 2010 223 which we can highlight a geographic viewer developed on OpenLayers, a PDA application developed on the Enebro core and the use of OGC standards, both for the use of base cartography through WMS, and for including access and edition via web through WFS-T. This project is a clear example of the new lines followed by the CMA on a commitment to use free software as key component for complex developments. Key words: Threatened flora, Web implementation, OGC, Free softwar

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

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    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

    Neotectonics and shoreline history of the Rock of Gibraltar, southern Iberia

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    Several sets of staircased Quaternary marine deposits can be observed along the Gibraltar coast ranging from 1 to 210 m above the present mean sea level. Geomorphological mapping establishes, from the relationship between shore, scree and dune sedimentary formations, five main morphotectonic steps on the Rock: marine terraces between 1 and 25 m, 30–60 m, 80–130 m, 180– 210 m, and above. Each terrace level and its slope-aeolian linked sediments is backed by a steep relict sea cliff margin, so forming a composite cliff. The most recent coastal landforms and sediments are associated with the last 250 ka linked to Oxygen Isotope Stages (OIS) 1, 3, 5 and 7. These landforms determine a morphosedimentary highstand-lowstand sequence, with several staircased and offlapped episodes, comprising a major morphotectonic step. A well-developed palaeocliff usually separates the highstand marine terraces of OIS 9 from those of OIS 7. The Gibraltar mean tectonic uplift value of 0.0570.01 mm/yr is maintained from 200 ka to the present. Before this, at least to 250 ka, the mean uplift rate was higher (0.3370.05 mm/yr), possibly compatible with major tectonic events in response to a NNW–SSE compressive stress field between Africa and Iberia.European Union (UE) EU MEDOC Programme: 2002-02-4.1-U-04

    WISE J061213.85-303612.5: a new T-dwarf binary candidate

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    Context. T and Y dwarfs are among the coolest and least luminous objects detected, and they can help to understand the properties of giant planets. Up to now, there are more than 350 T dwarfs that have been identified thanks to large imaging surveys in the infrared, and their multiplicity properties can shed light on the formation process. Aims. The aim of this work is to look for companions around a sample of seven ultracoool objects. Most of them have been discovered by the WISE observatory and have not been studied before for multiplicity. Methods. We observed a sample six T dwarfs and one L9 dwarf with the Laser Guide Star (LGS) and NAOS-CONICA, the adaptive optics (AO) facility, and the near infrared camera at the ESO Very Large Telescope. We observed all the objects in one or more near-IR filters (JHK_s). Results. From the seven observed objects, we have identified a subarcsecond binary system, WISE J0612-3036, composed of two similar components with spectral types of T6. We measure a separation of ρ = 350 ± 5 mas and a position angle of PA = 235 ± 1°. Using the mean absolute magnitudes of T6 dwarfs in the 2MASS JHK_s bands, we estimate a distance of d = 31 ± 6 pc and derive a projected separation of ρ ~ 11 ± 2 au. Another target, WISE J2255-3118, shows a very faint object at 1.̋3 in the K_s image. The object is marginally detected in H, and we derive a near infrared color of H − Ks> 0.1 mag. HST/WFC3 public archival data reveals that the companion candidate is an extended source. Together with the derived color, this suggests that the source is most probably a background galaxy. The five other sources are apparently single, with 3-σ sensitivity limits between H = 19–21 for companions at separations ≥ 0.̋5. Conclusions. WISE 0612-3036 is probably a new T-dwarf binary composed of two T6 dwarfs. As in the case of other late T-dwarf binaries, it shows a mass ratio close to 1, although its projected separation, ~11 au, is larger than the average (~5 au). Additional observations are needed to confirm that the system is bound

    Does size matter? Study of performance of pseudo-ELISAs based on molecularly imprinted polymer nanoparticles prepared for analytes of different sizes

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    The aim of this work is to evaluate whether the size of the analyte used as template for the synthesis of molecularly imprinted polymer nanoparticles (nanoMIPs) can affect their performance in pseudo-enzyme linked immunosorbent assays (pseudo-ELISAs). Successful demonstration of a nanoMIPs-based pseudo-ELISA for vancomycin (1449.3 g mol) was demonstrated earlier. In the present investigation, the following analytes were selected: horseradish peroxidase (HRP, 44 kDa), cytochrome C (Cyt C, 12 kDa) biotin (244.31 g mol) and melamine (126.12 g mol). NanoMIPs with a similar composition for all analytes were synthesised by persulfate-initiated polymerisation in water. In addition, core-shell nanoMIPs coated with polyethylene glycol (PEG) and imprinted for melamine were produced in organics and tested. The polymerisation of the nanoparticles was done using a solid-phase approach with the correspondent template immobilised on glass beads. The performance of the nanoMIPs used as replacement for antibodies in direct pseudo-ELISA (for the enzymes) and competitive pseudo-ELISA for the smaller analytes was investigated. For the competitive mode we rely on competition for the binding to the nanoparticles between free analyte and corresponding analyte-HRP conjugate. The results revealed that the best performances were obtained for nanoMIPs synthesised in aqueous media for the larger analytes. In addition, this approach was successful for biotin but completely failed for the smallest template melamine. This problem was solved using nanoMIP prepared by UV polymerisation in an organic media with a PEG shell. This study demonstrates that the preparation of nanoMIP by solid-phase approach can produce material with high affinity and potential to replace antibodies in ELISA tests for both large and small analytes. This makes this technology versatile and applicable to practically any target analyte and diagnostic field

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

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    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
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