9,753 research outputs found

    Multilingual Information Framework for Handling textual data in Digital Media

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    This document presents MLIF (Multi Lingual Information Framework), a high-level model for describing multilingual data across a wide range of possible applications in the translation/localization process within several multimedia domains (e.g. broadcasting interactive programs within a multilingual community)

    Giant magnetic anisotropy at nanoscale: overcoming the superparamagnetic limit

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    It has been recently observed for palladium and gold nanoparticles, that the magnetic moment at constant applied field does not change with temperature over the range comprised between 5 and 300 K. These samples with size smaller than 2.5 nm exhibit remanence up to room temperature. The permanent magnetism for so small samples up to so high temperatures has been explained as due to blocking of local magnetic moment by giant magnetic anisotropies. In this report we show, by analysing the anisotropy of thiol capped gold films, that the orbital momentum induced at the surface conduction electrons is crucial to understand the observed giant anisotropy. The orbital motion is driven by localised charge and/or spin through spin orbit interaction, that reaches extremely high values at the surfaces. The induced orbital moment gives rise to an effective field of the order of 103 T that is responsible of the giant anisotropy.Comment: 15 pages, 2 figures, submitted to PR

    Extended WKB method, resonances and supersymmetric radial barriers

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    Semiclassical approximations are implemented in the calculation of position and width of low energy resonances for radial barriers. The numerical integrations are delimited by t/T<<8, with t the period of a classical particle in the barrier trap and T the resonance lifetime. These energies are used in the construction of `haired' short range potentials as the supersymmetric partners of a given radial barrier. The new potentials could be useful in the study of the transient phenomena which give rise to the Moshinsky's diffraction in time.Comment: 12 pages, 4 figures, 3 table

    State-of-the-art techniques for calculating spectral functions in models for correlated materials

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    The dynamical mean field theory (DMFT) has become a standard technique for the study of strongly correlated models and materials overcoming some of the limitations of density functional approaches based on local approximations. An important step in this method involves the calculation of response functions of a multiorbital impurity problem which is related to the original model. Recently there has been considerable progress in the development of techniques based on the density matrix renormalization group (DMRG) and related matrix product states (MPS) implying a substantial improvement to previous methods. In this article we review some of the standard algorithms and compare them to the newly developed techniques, showing examples for the particular case of the half-filled two-band Hubbard model.Comment: 8 pages, 4 figures, to be published in EPL Perspective

    Reconstruction of the rotation center of the hip after oblong cups in revision total hip arthroplasty

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    Background The preoperative bone defect and the reconstruction of the center of rotation of the hip are critical in acetabular revision surgery. Uncemented oblong cups are employed in order to manage these issues. We analyzed the clinical results and rates of revision of two different uncemented oblong cups, the reconstruction of the center of rotation of the hip, as well as the rate of radiological loosening and possible risk factors. Materials and methods Forty-five patients (46 hips) underwent acetabular revision surgery using two different uncemented oblong cups.Weassessed the clinical results and the survival rate for revision and aseptic loosening. Intraoperative bone loss was classified according to Paprosky, and acetabular reconstruction was assessed according to Ranawat. The mean follow-up was 7.2 years (range 4–11 years). Results There were four re-revisions (three due to aseptic loosening); the survival rate for re-revision due to aseptic loosening was 60.1 % at seven years. The mean distance between the center of the femoral head prosthesis and the approximate center of the femoral head improved from 21.5 to 10.2 mm. Thirteen cups showed radiological loosening; the survival rate for radiological loosening at seven years was 40.54 %. A smaller postoperative horizontal distance was correlated with cup loosening. Conclusions Although optimal acetabular reconstruction can be achieved by using oblong uncemented cups in revision hip surgery, the clinical and radiological results are not encouraging. Excessive medialization of the cup may increase the rate of loosenin

    Doping and temperature dependence of Mn 3d states in A-site ordered manganites

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    We present a systematic study of the electronic structure in A-site ordered manganites as function of doping and temperature. The energy dependencies observed with soft x-ray resonant diffraction (SXRD) at the Mn L_{2,3} edges are compared with structural investigations using neutron powder diffraction as well as with cluster calculations. The crystal structures obtained with neutron powder diffraction reflect the various orbital and charge ordered phases and show an increase of the Mn-O-Mn bond angle as function of doping and temperature. Cluster calculations show that the observed spectral changes in SXRD as a function of doping are more pronounced than expected from an increase in bandwitdh due to the increase in Mn-O-Mn bond angle, and are best described by holes that are distributed at the neighbouring oxygen ions. These holes are not directly added to the Mn 3d shell, but centered at the Mn site. In contrast, the spectral changes in SXRD as function of temperature are best described by an increase of magnetic correlations. This demonstrates the strong correlations between orbitals and magnetic moments of the 3d states

    Estudio de la iluminación natural en la edificación

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    En la estación de radiación solar e iluminación de alta calidad del International Daylight Measurement Program (IDMP) en Madrid ubicada en la terraza norte de la E.T.S. de Arquitectura de la Universidad Politécnica de Madrid (40º 25’ N, 3º 41’ W) se está realizando un estudio conjunto entre profesores de la ETSAM y de la EUATM sobre la iluminación natural en la Edificación. Desde hace más de un año, se están midiendo iluminancias globales en superficies horizontales, en superficies verticales con las cuatro orientaciones (N, S, E y O) y en superficies inclinadas con distintos ángulos de inclinación mediante un domo semiesférico sobre el que se colocan los sensores fotométricos. Todas estas medidas para los tres tipos de cielo (despejado, parcialmente cubierto y cubierto). También se ha construido un modelo a escala de un local de la ETSAM con la finalidad de medir la iluminación natural simultáneamente en el local y en el modelo reducido. Una vez conocida la viabilidad del modelo se ha estudiado la iluminación natural que tendría dicho local, orientado al norte en la realidad, si estuviese orientado hacia el Sur, el Este o el Oeste. Con todo esto se han realizado varios trabajos de fin de máster del Máster en Técnicas y Sistemas de Edificación de la EUATM y se continúan realizando otros
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