3,716 research outputs found

    Coulomb interaction signatures in self-assembled lateral quantum dot molecules

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    We use photoluminescence spectroscopy to investigate the ground state of single self-assembled InGaAs lateral quantum dot molecules. We apply a voltage along the growth direction that allows us to control the total charge occupancy of the quantum dot molecule. Using a combination of computational modeling and experimental analysis, we assign the observed discrete spectral lines to specific charge distributions. We explain the dynamic processes that lead to these charge configurations through electrical injection and optical generation. Our systemic analysis provides evidence of inter-dot tunneling of electrons as predicted in previous theoretical work.Comment: 9 pages, 4 figure

    Glycogen in the Nervous System

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    'l'he relative value of different methods for combined light and electron microscopical studies of glycogen in the nervous tissue was investigated. Picroalcoholic fixatives preserve glycogen in a considerable amount but give an inadequate morphological image of glycogen distribution and are unsuitable for ultrastructural studies. Fixation by perfusion, with Dalton's chromeosmic fluid seems adequate for ultrastructural cytochemistry of glycogen. Furthermore it permits routine paraffin embedding of brain slices adjacent to those used for electron microscopy. Dimedone blocking is a necessary step for a selective staining of glycogen with PAS after osmic fixation. Enzymatic removal of glycogen in osmic fixed nervous tissue can be done In paraffin-embedded tissue. It can also be performed in glycolmethacrylate-embedded tissue without removal of the embedding medium. Paraphenylenediamine stains glycogen following periodic acid oxidation

    Patología escapulo-clavicular en un sujeto de Morella

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    X Congreso Nacional de Paleopatología. Univesidad Autónoma de Madrid, septiembre de 200

    Patología de ligamentos en la meseta tibial

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    X Congreso Nacional de Paleopatología. Univesidad Autónoma de Madrid, septiembre de 200

    Spectroscopy of the Lens Galaxy of Q0957+561A,B. Implications of a possible central massive dark object

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    We present new long-slit William Herschel Telescope spectroscopic observations of the lens galaxy G1 associated with the double-imaged QSO 0957+561A,B. The obtained central stellar velocity dispersion, sigma_l = 310 +/- 20 km/s, is in reasonable agreement with other measurements of this dynamical parameter. Using all updated measurements of the stellar velocity dispersion in the internal region of the galaxy (at angular separations < 1".5) and a simple isotropic model, we discuss the mass of a possible central massive dark object. It is found that the data of Falco et al. (1997) suggest the existence of an extremely massive object of (0.5-2.1) x 10E10/h M_\odot (80% confidence level), whereas the inclusion of very recent data (Tonry & Franx 1998, and this paper) substantially changes the results: the compact central mass must be \le 6 x10E9/h M_\odot at the 90% confidence level. We note that, taking into account all the available dynamical data, a compact nucleus with a mass of 10E9/h M_\odot (best fit) cannot be ruled out.Comment: 20 pages, 10 figures ApJ, in pres

    La desinstitucionalización y la crisis de las instituciones

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    .Hablar de instituciones se ha convertido en hablar de crisis de las instituciones. En este sentido, la noción de desinstitucionalización ocupa un lugar relevante en la reflexión institucional. Por este motivo, en este artículo se lleva a cabo una revisión del concepto de institución y de las principales críticas que ha recibido como paso previo al análisis más detallado del fenómeno desinstitucionalizador en la práctica psiquiátrica. Tal análisis lleva a la elaboración de una propuesta alternativa que cuestiona la pertinencia de seguir hablando de instituciones así como de procesos desinstitucionalizadores. Concretamente, se plantea que las especiales características de algunas prácticas psiquiátricas contemporáneas se ajustan mejor a la noción de ex-titución tomada de la obra de Serres

    Tratamiento numérico de materiales compuestos mediante la teoría de homogeneización

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    El presente trabajo se emmarca dentro de las teorías y métodos que hacen posible la representación por ordenador de los materiales compuesto. Como se sabe, la búsqueda de leyes matemáticas que determinan el comportamiento de esta clase de materiales ha sido objeto de estudio durante varias décadas. Pero, su elavada dificultad conduce a elaborar complejas teorías; o por el contrario, se utlizan grandes simplificaciones cuyo resultado genera modelos poco acertados.Postprint (published version

    Risk Factors for Nosocomial Bacterremia Due to Methicillin-Resistant Staphylococcus Aureus

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    In a prospective surveillance study (February 1990–December 1991) performed at a 1000-bed teaching hospital to identify risk factors for nosocomial methicillin-resistantStaphylococcus aureus (MRSA) bacteremia, 309 patients were found to be colonized (n=103; 33 %) or infected (n=206; 67 %) by MRSA. Sixty-three of them developed bacteremia. Compared with 114 patients who had nosocomial bacteremia caused by methicillin-sensitiveStaphylococcus aureus during the same period of time, MRSA bacteremic patients had more severe underlying diseases (p<0.01), were more often in intensive care units (p<0.01) and had received prior antibiotic therapy more frequently (p<0.01). To further identify risk factors for MRSA bacteremia, univariate and multivariate analyses of this series of 309 patients were performed using the occurrence of MRSA bacteremia as the dependent variable. Among 14 variables analyzed, intravascular catheterization, defined as one or more intravascular catheters in place for more than 48 h, was the only variable selected by a logistic regression model as an independent risk factor (OR=2.7, CI=1.1–6.6). The results of this study reinforce the concept that recent antibiotic therapy may predispose patients to MRSA infection and suggest that among patients colonized or infected by MRSA, those with intravascular catheters are at high risk of developing MRSA bacteremia
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