7,257 research outputs found
Ku-band system design study and TDRSS interface analysis
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
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
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
Factors affecting resistance of pressure vessel steels to repeated overloading, Welding. Journal, Vol. 32, p. 32-s, 1953, Reprint No. 84 (53-2)
Effect of isospin dependent cross-section on fragment production in the collision of charge asymmetric nuclei
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 , where n
varies from 47 to 59 and for , 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
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
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
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
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
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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