11,238 research outputs found

    Phenomenological model for symmetry breaking in chaotic system

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    We assume that the energy spectrum of a chaotic system undergoing symmetry breaking transitions can be represented as a superposition of independent level sequences, one increasing on the expense of the others. The relation between the fractional level densities of the sequences and the symmetry breaking interaction is deduced by comparing the asymptotic expression of the level-number variance with the corresponding expression obtained using the perturbation theory. This relation is supported by a comparison with previous numerical calculations. The predictions of the model for the nearest-neighbor-spacing distribution and the spectral rigidity are in agreement with the results of an acoustic resonance experiment.Comment: accepted for publication in Physical Review

    Analytical results for a Bessel function times Legendre polynomials class integrals

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    When treating problems of vector diffraction in electromagnetic theory, the evaluation of the integral involving Bessel and associated Legendre functions is necessary. Here we present the analytical result for this integral that will make unnecessary numerical quadrature techniques or localized approximations. The solution is presented using the properties of the Bessel and associated Legendre functions.Comment: 4 page

    Hydration and anomalous solubility of the Bell-Lavis model as solvent

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    We address the investigation of the solvation properties of the minimal orientational model for water, originally proposed by Bell and Lavis. The model presents two liquid phases separated by a critical line. The difference between the two phases is the presence of structure in the liquid of lower density, described through orientational order of particles. We have considered the effect of small inert solute on the solvent thermodynamic phases. Solute stabilizes the structure of solvent, by the organization of solvent particles around solute particles, at low temperatures. Thus, even at very high densities, the solution presents clusters of structured water particles surrounding solute inert particles, in a region in which pure solvent would be free of structure. Solute intercalates with solvent, a feature which has been suggested by experimental and atomistic simulation data. Examination of solute solubility has yielded a minimum in that property, which may be associated with the minimum found for noble gases. We have obtained a line of minimum solubility (TmS) across the phase diagram, accompanying the line of maximum in density (TMD). This coincidence is easily explained for non-interacting solute and it is in agreement with earlier results in the literature. We give a simple argument which suggests that interacting solute would dislocate TmS to higher temperatures

    Molecular Evaluation of exons 8 and 22 of the SHANK3 gene in Autism Spectrum Disorders

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    Autism spectrum disorders are a group of neurodevelopmental disorders with a complex and heterogeneous etiology. Studies have shown that genetic factors play an important role in the aetiology of these diseases. Recently, de novo mutations, frameshifts and deletions have been described in the SHANK3 gene, also known as ProSAP2 gene, which encodes a synaptic scaffolding protein. All the participants of this study had normal karyotypes and underwent screening for Fragile-X syndrome. Subsequently, they were analyzed by direct sequencing of different points of exons 8 and 22 of the SHANK3 gene. None of the study participants presented with changes in these regions. These findings may be due to the fact that mutations, deletions and duplications of the SHANK3 gene are rare

    OXIDATION INFLUENCE ON THE QUASICRYSTALLINE PHASES OF ALLOYS Al62.5Cu25Fe12.5 AND Al65Ni15Co20

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    In this article we will cover a study of the formation of icosahedral and decagonal phases two quasicrystals Al62.5Cu25Fe12.5 and Al65Ni15Co20 oxidation of influence in this alloy. For this purpose research used the diffraction of X-ray, scanning electron microscopy/energy dispersive spectroscopy, differential scanning calorimetry and thermogravimetric analysis. The results displayed found aspects of morphological structural as well as the surface of the two compositions of quasicrystals, these were prepared and obtained in electric arc furnaces and induction and arc. Oxidation of Al62.5Cu25Fe12.5 alloy, intermetallic phases presented with combinations of alloying elements and above 675°C it was observed that the crystalline phase is stable. In icosahedral phase oxidation of aluminum forms a dense layer on the passivating outer most surface of the quasicrystal which causes depletion in both copper and iron. In Al65Ni15Co20 nominal composition of oxygen interaction occurs on the surface of symmetry 10 times plane perpendicular vector .The formation of a thin film of aluminum oxide having well-ordered hexagonal structure and with the opposition area decagonal phase with the lateral size of approximately 35Å

    Linfangioleiomiomatose pulmonar inicial provável e linfangioleiomioma mediastinal

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    A 68 year old woman was submitted to a mediastinal lymphangioleiomyoma resection found in a follow-up study of lower left lung resection due to bronchiectasis complicated by chylothorax. This led to a revaluation of the pulmonary specimen that revealed, in addition to inflammatory bronchiectasis, small spindle cell nodules in the lung parenchyma, similar to minute pulmonary meningothelial-like nodules, but with smooth muscle actin immunohistochemical positivity. The possibility of initial pulmonary development of lymphangioleiomyomatosis is discussed

    Ion-ion correlations: an improved one-component plasma correction

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    Based on a Debye-Hueckel approach to the one-component plasma we propose a new free energy for incorporating ionic correlations into Poisson-Boltzmann like theories. Its derivation employs the exclusion of the charged background in the vicinity of the central ion, thereby yielding a thermodynamically stable free energy density, applicable within a local density approximation. This is an improvement over the existing Debye-Hueckel plus hole theory, which in this situation suffers from a "structuring catastrophe". For the simple example of a strongly charged stiff rod surrounded by its counterions we demonstrate that the Poisson-Boltzmann free energy functional augmented by our new correction accounts for the correlations present in this system when compared to molecular dynamics simulations.Comment: 5 pages, 2 figures, revtex styl
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