7,257 research outputs found

    Ku-band system design study and TDRSS interface analysis

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    The capabilities of the Shuttle/TDRSS link simulation program (LinCsim) were expanded to account for radio frequency interference (RFI) effects on the Shuttle S-band links, the channel models were updated to reflect the RFI related hardware changes, the ESTL hardware modeling of the TDRS communication payload was reviewed and evaluated, in LinCsim the Shuttle/TDRSS signal acquisition was modeled, LinCsim was upgraded, and possible Shuttle on-orbit navigation techniques was evaluated

    The Discovery of an X-ray/UV Stellar Flare from the Late-K/Early-M Dwarf LMC 335

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    We report the discovery of an X-ray/UV stellar flare from the source LMC 335, captured by XMM-Newton in the field of the Large Magellanic Cloud. The flare event was recorded continuously in X-ray for its first 10 hours from the precursor to the late decay phases. The observed fluxes increased by more than two orders of magnitude at its peak in X-ray and at least one in the UV as compared to quiescence. The peak 0.1-7.0 keV X-ray flux is derived from the two-temperature APEC model to be ~(8.4 +/- 0.6) x 10^-12 erg cm-2 s-1. Combining astrometric information from multiple X-ray observations in the quiescent and flare states, we identify the NIR counterpart of LMC 335 as the 2MASS source J05414534-6921512. The NIR color relations and spectroscopic parallax characterize the source as a Galactic K7-M4 dwarf at a foreground distance of (100 - 264) pc, implying a total energy output of the entire event of ~(0.4 - 2.9) x 10^35 erg. This report comprises detailed analyses of this late-K / early-M dwarf flare event that has the longest time coverage yet reported in the literature. The flare decay can be modeled with two exponential components with timescales of ~28 min and ~4 hours, with a single component decay firmly ruled out. The X-ray spectra during flare can be described by two components, a dominant high temperature component of ~40-60MK and a low temperature component of ~10MK, with a flare loop length of about 1.1-1.3 stellar radius.Comment: 35 pages, 6 figures, 5 tables, accepted for publication in Ap

    On the Relationship between Resolution Enhancement and Multiphoton Absorption Rate in Quantum Lithography

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    The proposal of quantum lithography [Boto et al., Phys. Rev. Lett. 85, 2733 (2000)] is studied via a rigorous formalism. It is shown that, contrary to Boto et al.'s heuristic claim, the multiphoton absorption rate of a ``NOON'' quantum state is actually lower than that of a classical state with otherwise identical parameters. The proof-of-concept experiment of quantum lithography [D'Angelo et al., Phys. Rev. Lett. 87, 013602 (2001)] is also analyzed in terms of the proposed formalism, and the experiment is shown to have a reduced multiphoton absorption rate in order to emulate quantum lithography accurately. Finally, quantum lithography by the use of a jointly Gaussian quantum state of light is investigated, in order to illustrate the trade-off between resolution enhancement and multiphoton absorption rate.Comment: 14 pages, 7 figures, submitted, v2: rewritten in response to referees' comments, v3: rewritten and extended, v4: accepted by Physical Review

    Effect of isospin dependent cross-section on fragment production in the collision of charge asymmetric nuclei

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    To understand the role of isospin effects on fragmentation due to the collisions of charge asymmetric nuclei, we have performed a complete systematical study using isospin dependent quantum molecular dynamics model. Here simulations have been carried out for 124Xn+124Xn^{124}X_{n}+ ^{124}X_{n}, where n varies from 47 to 59 and for 40Ym+40Ym^{40}Y_{m}+ ^{40}Y_{m}, where m varies from 14 to 23. Our study shows that isospin dependent cross-section shows its influence on fragmentation in the collision of neutron rich nuclei

    O assistente social como mediador cultural em escolas públicas dos bairros de Guamá e Terra firme

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    I Congresso Internacional América Latina e Interculturalidade: América Latina e Caribe: cenários linguístico-culturais contemporâneos, 07, 08 e 09 de novembro de 2013 - UNILAA intervenção do Assistente Social nas atividades de arte e cultura nas instituições de ensino fundamental e médio nos bairros do Guamá e da Terra Firme. Estudos anteriores constatam que estes não são apenas espaços de violência, como registra a mídia. São espaços multiculturais e agregadores de cultura antiviolência, onde os sujeitos artistas utilizam a arte como meio de transformação social, através do método fenomenológico busco contribuir para a sistematização da intervenção do assistente social na área da educação e cultura, identificando as atividades de arte e cultura nas instituições de ensino fundamental e médio, importância nas instituições em que são desenvolvidas e habilidades requeridas ao profissional de Serviço Social. A metodologia conduziu a investigação nos respectivos bairros com os alunos que estudam nas instituições de ensino fundamental e médio nos bairros, por meio de aplicação de questionários sócio­econômico­cultural que ao definir cultura identificaram as manifestações culturais que estavam ocorrendo no mês (junho/2013) em que o questionário foi aplicado, quanto ao fazer profissional do Serviço Social, a maioria dos alunos da escola pública estadual relacionam o trabalho do assistente social com a prestação de ajuda e auxílio. Os alunos da escola pública federal demonstraram maior efetividade e segurança na resposta, em consonância com o Código de Ética do Assistente Social, também foi realizada entrevista semi­estruturada com a Assistente Social das instituições de ensino. Segundo a pesquisa identifica­se a sobrecarga do profissional do serviço social com as demandas postas pelos alunos no processo de ensino e aprendizagem, de tal modo que não possa acompanhar atividades de arte e cultura desenvolvidas nas instituições de ensino, e por meio de levantamentos bibliográficos e visitas de observação ao local de pesquisa foi possível identificar as atividades, projetos de extensão de arte e cultura nas instituições de ensino

    Long-range surface plasmon polariton excitation at the quantum level

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    We provide the quantum mechanical description of the excitation of long-range surface plasmon polaritons (LRSPPs) on thin metallic strips. The excitation process consists of an attenuated-reflection setup, where efficient photon-to-LRSPP wavepacket-transfer is shown to be achievable. For calculating the coupling, we derive the first quantization of LRSPPs in the polaritonic regime. We study quantum statistics during propagation and characterize the performance of photon-to-LRSPP quantum state transfer for single-photons, photon-number states and photonic coherent superposition states.Comment: 9 pages, 6 figures, RevTeX4; Accepted versio

    CD4+ T-cell responses to Epstein-Barr virus (EBV) latent-cycle antigens and the recognition of EBV-transformed lymphoblastoid cell lines

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    There is considerable interest in the potential of Epstein-Barr virus (EBV) latent antigen-specific CD4+^+ T cells to act as direct effectors controlling EBV-induced B lymphoproliferations. Such activity would require direct CD4+^+ T-cell recognition of latently infected cells through epitopes derived from endogenously expressed viral proteins and presented on the target cell surface in association with HLA class II molecules. It is therefore important to know how often these conditions are met. Here we provide CD4+^+ epitope maps for four EBV nuclear antigens, EBNA1, -2, -3A, and -3C, and establish CD4+^+ T-cell clones against 12 representative epitopes. For each epitope we identify the relevant HLA class II restricting allele and determine the efficiency with which epitope-specific effectors recognize the autologous EBV-transformed B-lymphoblastoid cell line (LCL). The level of recognition measured by gamma interferon release was consistent among clones to the same epitope but varied between epitopes, with values ranging from 0 to 35% of the maximum seen against the epitope peptide-loaded LCL. These epitope-specific differences, also apparent in short-term cytotoxicity and longer-term outgrowth assays on LCL targets, did not relate to the identity of the source antigen and could not be explained by the different functional avidities of the CD4+^+ clones; rather, they appeared to reflect different levels of epitope display at the LCL surface. Thus, while CD4+^+ T-cell responses are detectable against many epitopes in EBV latent proteins, only a minority of these responses are likely to have therapeutic potential as effectors directly recognizing latently infected target cells

    Influence of the Coulomb Interaction on the Chemical Equilibrium of Nuclear Systems at Break-Up

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    The importance of a Coulomb correction to the formalism proposed by Albergo et al. for determining the temperatures of nuclear systems at break-up and the ensities of free nucleon gases is discussed. While the proposed correction has no effect on the temperatures extracted based on double isotope ratios, it becomes non-negligible when such temperatures or densities of free nucleon gases are extracted based on multiplicities of heavier fragments of different atomic numbers

    Magnifying perfect lens and superlens design by coordinate transformation

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    The coordinate transformation technique is applied to the design of perfect lenses and superlenses. In particular, anisotropic metamaterials that magnify two-dimensional planar images beyond the diffraction limit are designed by the use of oblate spheroidal coordinates. The oblate spheroidal perfect lens or superlens can naturally be used in reverse for lithography of planar subwavelength patterns.Comment: 8 pages, 8 figures, v2: submitted, v3: accepted by Physical Review
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