90 research outputs found

    The atomic orbitals of the topological atom

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    The effective atomic orbitals have been realized in the framework of Bader’s atoms in molecules theory for a general wavefunction. This formalism can be used to retrieve from any type of calculation a proper set of orthonormalized numerical atomic orbitals, with occupation numbers that sum up to the respective Quantum Theory of Atoms in Molecules (QTAIM) atomic populations. Experience shows that only a limited number of effective atomic orbitals exhibit significant occupation numbers. These correspond to atomic hybrids that closely resemble the core and valence shells of the atom. The occupation numbers of the remaining effective orbitals are almost negligible, except for atoms with hypervalent character. In addition, the molecular orbitals of a calculation can be exactly expressed as a linear combination of this orthonormalized set of numerical atomic orbitals, and the Mulliken population analysis carried out on this basis set exactly reproduces the original QTAIM atomic populations of the atoms. Approximate expansion of the molecular orbitals over a much reduced set of orthogonal atomic basis functions can also be accomplished to a very good accuracy with a singular value decomposition procedure

    Adaptando un sistema de Wikis para su uso educativo

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    La aplicación de la Web 2.0 a la enseñanza está favoreciendo nuevos modelos y metodologías de aprendizaje. Los Wikis constituyen una herramienta efectiva para la escritura colaborativa de documentos. En la Universidad se están utilizando Wikis como soporte al desarrollo de actividades en grupo. Las herramientas para crear Wikis presentan algunas limitaciones para su uso educativo. Con el objetivo de solventar estas limitaciones, este trabajo presenta las modificaciones y mejoras realizadas al sistema de gestión de Wikis MediaWiki. Las extensiones desarrolladas tuvieron como objetivo facilitar la evaluación de los alumnos y la gestión de grupos de usuarios.Este trabajo ha sido realizado en el contexto del proyecto 08SIN009305PR (“novos entornos colaborativos para o ensino”) de la Xunta de Galicia

    Local spins: improved Hilbert-space analysis

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    The decomposition of for a general wave function has been carried out in the framework of the Hilbert-space analysis. The one and two-center components fulfill all physical requirements imposed to date. An inherent ambiguity of the Hilbert-space decomposition of a two-electron quantity, in particular using a Mulliken-type scheme, is also discussed in detail. The formalism of effective atomic densities has allowed us to derive in a simple manner appropriate expressions for the decomposition of in the framework of Hilbert space analysis that are consistent with Mulliken population analysis and related quantities. Using a particular mapping we have derived the Hilbert-space expressions also in the framework of Löwdin population analysis in a straightforward manner. The numerical results obtained with proved to be more robust and reliabl

    Kardar-Parisi-Zhang universality in first-passage percolation: the role of geodesic degeneracy

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    We have characterized the scaling behavior of the first-passage percolation (FPP) model on two types of discrete networks, the regular square lattice and the disordered Delaunay lattice, thereby addressing the effect of the underlying topology. Several distribution functions for the link-times were considered. The asymptotic behavior of the fluctuations for both the minimal arrival time and the lateral deviation of the geodesic path are in perfect agreement with the Kardar-Parisi-Zhang (KPZ) universality class regardless of the type of the link-time distribution and of the lattice topology. Pre-asymptotic behavior, on the other hand, is found to depend on the uniqueness of geodesics in absence of disorder in the local crossing times, a topological property of lattice directions that we term geodesic degeneracy. This property has important consequences on the model, as for example the well-known anisotropic growth in regular lattices. In this work we provide a framework to understand its effect as well as to characterize its extent.We acknowledge fruitful conversations with E. Korutcheva. This work has been supported by MINECO/FEDER (Spain/EU) grants FIS2015-66020-C2-1-P and FIS2015-69167-C2-1-P

    Age-associated differences in clinical manifestations and laboratory parameters during a dengue virus type 4 outbreak in Argentina

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    Infection by any of the four dengue virus (DENV) serotypes produces a wide spectrum of clinical illness in humans. Differences in clinical manifestation and severity have been associated with secondary heterologous infection, patient age, and virus serotype. In this context, this retrospective study sought to analyze the presentation of dengue in patients during the 2014 DENV-4 outbreak affecting the City of Orán, Salta Province, Argentina. Demographic data, clinical manifestations, and laboratory abnormalities of laboratory-confirmed dengue patients were compared between age groups and between patients with and without warning signs. Of 301 patients with laboratory-confirmed dengue, 37.9% presented dengue with warning signs. Although nearly half of all patients had secondary DENV infections, no severe dengue cases, or deaths were reported. Furthermore, no association was found between incidence of warning signs and pre-existing immunity to DENV. Pediatric patients were least likely to present warning signs and showed significantly decreased risk of fever, retro-orbital pain, arthalgia, diarrhea and thrombocytopenia, and higher risk of rash compared to older patients. Female patients of all ages were also at higher risk of developing several symptoms. The characterization of DENV-4 infection in humans, a DENV serotype recently reported in Argentina, revealed differences in clinical manifestations, laboratory parameters and the presence/absence of warning signs based on age group. Further investigation of these age-related differences should contribute to better assessment of dengue disease in at risk populations.Fil: Byrne, Alana Brooke. Fundación para la Investigación en Infectología Infantil; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gutierrez, Francisco Guillermo. Hospital San Vicente de Paul; Argentina. Universidad Nacional de Tucumán. Facultad de Medicina; ArgentinaFil: Bruno, Agostina Alejandra. Hospital San Vicente de Paul; ArgentinaFil: Cordoba, María Teresa. Hospital San Vicente de Paul; ArgentinaFil: Bono, María M.. Hospital San Vicente de Paul; ArgentinaFil: Polack, Fernando Pedro. Fundación para la Investigación en Infectología Infantil; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Talarico, Laura Beatriz. Fundación para la Investigación en Infectología Infantil; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Quipildor, Marcelo Omar. Hospital San Vicente de Paul; Argentin

    The human CD53 gene, coding for a four transmembrane domain protein, maps to chromosomal region 1p13

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    The rat OX44/CD53 protein is the prototypic member of a"novel" family of proteins. These proteins are characterizedby four highly hydrophobic transmembrane domains, twosmall extracellular domains, one of which is extensively N-glycosylated,and both the amino and the carboxy terminus intracytoplasmic.This work has been supported by grants from Fundación Ramón Areces and CICYT (SAL90-0209 and SAL91-0043) to P.A.L. and FIS(92-0889) to S.R.CS

    Clinical utility of intralesional methotrexate to distinguish crateriform keratinocytic tumors before surgery

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    Clinical utility of intralesional methotrexate to distinguish crateriform keratinocytic tumors before surgeryDear Editors,Keratoacanthoma (KA) and cutaneous squamous cell carci-noma (CSCC) may adopt an identical crateriform morpho-logy. Nowadays, the debate about whether KA is a distinct entity, or a low-grade variant of cutaneous squamous cell carcinoma (CSCC) still persists. Since CSCC is a more ag-gressive neoplasm, misdiagnosing crateriform lesions may have a negative impact on the patient's prognosis. Evaluating a partial biopsy is extremely challenging to confidently dis-tinguish KA from CSCC [1]. No distinctive gene expression profiles have been identified and no pathognomonic criteria to unequivocally differentiate between KA and CSCC exist [2]. Consequently, the surgical approach remains the gold standard in the management of crateriform tumors, especi-ally those arising on the face

    Segmentación de Lesiones Hepáticas Adquiridas por Resonancia Magnética.

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    La detección y caracterización de lesiones hepáticas resulta fundamental en la práctica clínica, desde las etapas de diagnosis hasta la evolución de la respuesta terapéutica. La resonancia magnética hepática es una práctica habitual en la localización y cuantificación de las lesiones. Se presenta la segmentación automática de lesiones hepáticas en imágenes potenciadas en T1. La segmentación propuesta se basa en un procesado de difusión anisotrópica 3D adaptativo y carente de parámetros de control. A la imagen realzada se le aplica una combinación de técnicas de detección de bordes 3D, análisis del histograma, post procesado morfológico y evolución de un contorno activo 3D. Éste último fusiona información de apariencia y forma de la lesión
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