5,945 research outputs found

    Supersymmetrization of the Radiation Damping

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    We construct a supersymmetrized version of the model to the radiation damping \cite{03} introduced by the present authors \cite{ACWF}. We dicuss its symmetries and the corresponding conserved Noether charges. It is shown this supersymmetric version provides a supersymmetric generalization of the Galilei algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action can be splited into dynamically independent external and internal sectors.Comment: 9 page

    Magnetic reconfiguration of MnAs/GaAs(001) observed by Magnetic Force Microscopy and Resonant Soft X-ray Scattering

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    We investigated the thermal evolution of the magnetic properties of MnAs epitaxial films grown on GaAs(001) during the coexistence of hexagonal/orthorhombic phases using polarized resonant (magnetic) soft X-ray scattering and magnetic force microscopy. The results of the diffuse satellite X-ray peaks were compared to those obtained by magnetic force microscopy and suggest a reorientation of ferromagnetic terraces as temperature rises. By measuring hysteresis loops at these peaks we show that this reorientation is common to all ferromagnetic terraces. The reorientation is explained by a simple model based on the shape anisotropy energy. Demagnetizing factors were calculated for different configurations suggested by the magnetic images. We noted that the magnetic moments flip from an in-plane mono-domain orientation at lower temperatures to a three-domain out-of-plane configuration at higher temperatures. The transition was observed when the ferromagnetic stripe width L is equal to 2.9 times the film thickness d. This is in good agreement with the expected theoretical value of L = 2.6d.Comment: 16 pages in PD

    Invasive Meningococcal Disease Unraveling a Novel Mutation in the C5 Gene in a Portuguese Family

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    Although bacterial meningitis is a rare presentation of a congenital immunodeficiency, invasive meningococcal disease is classically associated with complement deficiencies. We report a patient from a consanguineous kindred presenting with an invasive meningococcal disease caused by serogroup B meningococcus that revealed an underlying C5 deficiency caused by a novel mutation in the C5 gene.info:eu-repo/semantics/publishedVersio

    X-ray method to study temperature-dependent stripe domains in MnAs/GaAs(001)

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    MnAs films grown on GaAs (001) exhibit a progressive transition between hexagonal (ferromagnetic) and orthorhombic (paramagnetic) phases at wide temperature range instead of abrupt transition during the first-order phase transition. The coexistence of two phases is favored by the anisotropic strain arising from the constraint on the MnAs films imposed by the substrate. This phase coexistence occurs in ordered arrangement alternating periodic terrace steps. We present here a method to study the surface morphology throughout this transition by means of specular and diffuse scattering of soft x-rays, tuning the photon energy at the Mn 2p resonance. The results show the long-range arrangement of the periodic stripe-like structure during the phase coexistence and its period remains constant, in agreement with previous results using other techniques.Comment: 4 pages, 4 figures, submitted to Applied Physics Letter

    Conservação de recursos genéticos animais de grande porte na Amazônia Oriental (BAGAM).

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    Os búfalos da raça Carabao e do Tipo Baio compõem pequenas populações no País, sofrendo assim, ameaças de extinção e fortes riscos de descaracterização. O Núcleo de conservação desenvolve estudos voltados à avaliação de parâmetros produtivos e reprodutivos das espécies supracitadas. O objetivo deste trabalho foi acompanhar as ações de conservação genética no Banco de Germoplasma Animal da Amazônia Oriental/BAGAM, com ênfase na coleta, caracterização e documentação dessas espécies de importância socioeconômica para a região. Localizado na ilha de Marajó/PA, o BAGAM atualmente mantêm 238 búfalos entre Carabaos e Baios. Os dados de características fenotípicas, morfométricas, moleculares, assim como, parâmetros produtivos e reprodutivos estão sendo organizados e documentados em bancos de dados de espécies em conservação.PIBIC-2011

    A New Approach to Canonical Quantization of the Radiation Damping

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    Inspired in some works about quantization of dissipative systems, in particular of the damped harmonic oscillator\cite{MB,RB,12}, we consider the dissipative system of a charge interacting with its own radiation, which originates the radiation damping (RD). Using the indirect Lagrangian representation we obtained a Lagrangian formalism with a Chern-Simons-like term. A Hamiltonian analysis is also done, what leads to the quantization of the system.Comment: 5 page

    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

    Effect of concentration of the diazoalcene molybdenum complex immobilized in ureasil matrix

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    The complex trans-[FMo(NNCHCHCHCH2CH3)(Ph2PCH2CH2PPh2)2][BPh4], was dispersed in a hybrid matrix synthesized by a sol-gel process. The host matrix of the so-called ureasil is a network of silica to which oligopolyoxyethylene chains [POE, (OCH2CH2)n] are grafted by means of urea cross-links. The free complex and sol-gel materials were characterized by thermal analysis (DSC), surface analysis (XPS) and spectroscopic methods (FT-IR and UV/Vis). The data gathered indicates that the molybdenum(IV) complex is immobilized in the host matrix, and it exhibits structural properties different from those of the free form. These differences could arise either from distortions caused by steric effects imposed by the structure of hybrid matrix or by interactions with the matrix. These materials shows potential applications in heterogeneous catalysis in mild conditions
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