10,794 research outputs found

    Entropy, fidelity, and double orthogonality for resonance states in two-electron quantum dots

    Get PDF
    Resonance states of a two-electron quantum dot are studied using a variational expansion with both real basis-set functions and complex scaling methods. The two-electron entanglement (linear entropy) is calculated as a function of the electron repulsion at both sides of the critical value, where the ground (bound) state becomes a resonance (unbound) state. The linear entropy and fidelity and double orthogonality functions are compared as methods for the determination of the real part of the energy of a resonance. The complex linear entropy of a resonance state is introduced using complex scaling formalism

    On electrons and hydrogen-bond connectivity in liquid water

    Full text link
    The network connectivity in liquid water is revised in terms of electronic signatures of hydrogen bonds (HBs) instead of geometric criteria, in view of recent X-ray absorption studies. The analysis is based on ab initio molecular-dynamics simulations at ambient conditions. Even if instantaneous thread-like structures are observed in the electronic network, they continuously reshape in oscillations reminiscent of the r and t modes in ice (tau~170 fs). However, two water molecules initially joint by a HB remain effectively bound over many periods regardless of its electronic signature.Comment: 4 pages, 4 figure

    Archival education and outreach: promoting communal identity through education

    Get PDF
    Archival outreach programs serve a key role in the preservation and promotion of public history. Community based educational programs sponsored and implemented by archival repositories allow actual, as well as potential, patrons to learn about their local history and to familiarize themselves with archival materials. It is the purpose of this thesis to explore the postmodern archival perspective and to propose universal program models which can be adapted to facilitate educational outreach in archival repositories of various staff sizes and organizational affiliations. This study will appraise the similarities and differences of a variety of current public outreach programs with a focus on three distinct areas: how an archival organization chooses which target audiences will be best served by public outreach initiatives; how an archives can most efficiently fund and market these outreach projects; and how local communities can utilize archival repositories to build and strengthen their communal identities

    El desajuste financiero y la elección de régimen cambiario

    Get PDF
    (Disponible en idioma inglés únicamente) El desajuste financiero se está convirtiendo en algo corriente en América Latina. Los años 90 se caracterizaron por una gran inestabilidad en la magnitud y el costo de los flujos de capitales. La correlación de los vaivenes de los capitales entre países distintos sugiere que la calidad de las políticas de los mercados emergentes, además de los factores mundiales, han sido los factores principales de esta situación. Por lo tanto, la responsabilidad del desajuste financiero se ha alejado de las políticas internas inadecuadas. En vez de ello, el paradigma se ha desplazado hacia uno de determinar cuáles políticas internas o internacionales son las más eficaces para atemperar las repercusiones desestabilizadoras de los flujos de capitales inherentemente inestables.

    "Resultados preliminares de la campaña marina realizada en el precontinente catalán entre los cañones de la Fonera y Blanes"

    Get PDF
    Los autores hacen un estudio preliminar de la estructura y unidades sedimentarias deducidas a partir de los perfiles sísmicos y testigos obtenidos en el sector de la plataforma continental comprendida entre los cañones de la Fonera y Blanes (Costa Brava, Gerona), y establece una correlación con los ya estudiados del Ampurdán y del Roussillon. Asimismo, se describe una secuencia del Cuaternario reciente a partir de los testigos de gravedad estudiados

    An improved limit on the neutrino mass with CMB and redshift-dependent halo bias-mass relations from SDSS, DEEP2, and Lyman-Break Galaxies

    Full text link
    We use measurements of luminosity-dependent galaxy bias at several different redshifts, SDSS at z=0.05z=0.05, DEEP2 at z=1z=1 and LBGs at z=3.8z=3.8, combined with WMAP five-year cosmic microwave background anisotropy data and SDSS Red Luminous Galaxy survey three-dimensional clustering power spectrum to put constraints on cosmological parameters. Fitting this combined dataset, we show that the luminosity-dependent bias data that probe the relation between halo bias and halo mass and its redshift evolution are very sensitive to sum of the neutrino masses: in particular we obtain the upper limit of mν<0.28\sum m_{\nu}<0.28eV at the 95% confidence level for a ΛCDM+mν\Lambda CDM + m_{\nu} model, with a σ8\sigma_8 equal to σ8=0.759±0.025\sigma_8=0.759\pm0.025 (1σ\sigma). When we allow the dark energy equation of state parameter ww to vary we find w=1.30±0.19w=-1.30\pm0.19 for a general wCDM+mνwCDM+m_{\nu} model with the 95% confidence level upper limit on the neutrino masses at mν<0.59\sum m_{\nu}<0.59eV. The constraint on the dark energy equation of state further improves to w=1.125±0.092w=-1.125\pm0.092 when using also ACBAR and supernovae Union data, in addition to above, with a prior on the Hubble constant from the Hubble Space Telescope.Comment: 9 pages, 6 figures, submitted to PR

    Una nueva especie de Tarracoblaniulus Mauriès & Vicente, 1977: descripción, desarrollo postembrionario, ciclo vital y distribución espacial (Diplopoda, Julida, Blaniulidae)

    Get PDF
    Tarracoblaniulus phantasmanus n. sp. is described from Tarragona province, Spain and compared with the only known other species known in the genus, T. lagari Mauriès & Vicente, 1977, from which it differs mainly in having only 5, instead of 15 or more, straight spines on the posterior gonopod. The female vulva (unknown in T. lagari) is very different from all known blaniulid vulvae. Based on a large number of specimens, the postembryonic development (euanamorphosis) from stadium II onward is described. This is highly variable, with three to six apodous body rings in stadium IV, which is the most variable number so far recorded in Blaniulidae. Accordingly, specimens beyond stadium VIII could not be assigned to a specific stadium. At least some males are morphologically distinguishable in stadium IV, morphologically mature males appear in stadium VIII, possibly already in stadium VII. The life cycle of the new species is tentatively suggested to involve at least three years. The monthly mean density of the total population was 28.82 ind/m2 across the whole soil profile. Statistically significant differences in density values between months and Spearman’s rank correlation analyses between the monthly mean values of density and temperature show that T. phantasmanus presents a maximum density in the coldest months and a minimum one in the summer. Significant differences between monthly mean densities of different soil levels and the Usher index values show that during the spring and summer T. phantasmanus is concentrated in the mineral horizon A. In autumn, during winter and up to early spring, the population shows a clear tendency to move up towards horizon H and horizon L/F. Concerning horizontal distribution, Morisita index monthly values for each of the horizons indicate that the species is distributed in patches.Se describe Tarracoblaniulus phantasmanus n. sp., especie encontrada en la provincia de Tarragona (España), y se compara con la única especie conocida del género, T. lagari Mauriès & Vicente, 1977, de la cual difiere principalmente por tener sólo 5 espinas, en lugar de 15 o más, en el gonópodo posterior. La vulva de la hembra (desconocida en T. lagari) es muy distinta a todas las vulvas conocidas de blaniúlidos. En base a los numerosos ejemplares disponibles, se describe asimismo el desarrollo postembrionario (euanamorphosis) a partir del estadio II. Este desarrollo se manifiesta muy variable, con tres a seis anillos ápodos en el tronco del estadio IV, número que con mucho es el más elevado encontrado en Blaniulidae. De acuerdo con estos resultados, los ejemplares pertenecientes a estadios posteriores al VII no pueden ser asignados a un estadio específico. Algunos machos son morfológicamente distinguibles en el estadio IV y los machos morfológicamente maduros aparecen en el estadio VIII y posiblemente ya lo sean en el estadio VII. El ciclo vital de la nueva especie parece sugerir una duración de al menos tres años. La densidad mensual media registrada para el total de la población es de 28.82 ind/m2 en el conjunto del perfil edáfico. Diferencias estadísticamente significativas entre los valores de densidad mensuales y el análisis de correlación de rango de Spearman entre la densidad mensual media y la temperatura muestran que T. phantasmanus presenta una densidad máxima en los meses más fríos y un valor mínimo durante el verano. Diferencias siginificativas entre las densidades mensuales medias registradas en los distintos horizontes edáficos y los valores del índice de Usher, ponen de manifiesto que durante la primavera y el verano T. phantasmanus se situa principalmente en el horizonte mineral A. Durante el otoño, el invierno y hasta principios de la primavera, la población muestra una clara tendencia a ocupar los horizontes superiores H y L/F. En cuanto a la distribución horizontal, los valores mensuales del índice de Morisita obtenidos para cada uno de los horizontes indican que la especie tiene una distribución agregativa
    corecore