189 research outputs found

    USO DO DUBLIN CORE NA DESCRIÇÃO DE OBRAS RARAS NA WEB: \ud A COLEÇÃO DA BIBLIOTECA BRASILIANA DIGITAL

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    Acessível ao público desde junho de 2009, a Biblioteca Brasiliana Digital, da Universidade de \ud São Paulo tem por objetivo facultar para a pesquisa, a maior Brasiliana custodiada por uma \ud universidade. Sua intenção é disponibilizar virtualmente parte do acervo da Universidade \ud oferecendo-se como um instrumento útil e funcional para a pesquisa e o estudo dos temas e \ud cultura brasileiros, além de oferecer um modelo tecnológico de gestão que possa ser difundido \ud a outras coleções, acervos e instituições. Este trabalho apresenta os resultado da implantação \ud de um esquema de metadados baseado no formato Dublin Core, para a descrição de obras \ud raras e especiais na web. Especificamente, apresenta os procedimentos e processos de \ud descrição de conteúdos das diversas tipologias documentais (livros, periódicos, gravuras etc.) \ud e formatos digitais (pdf, jpeg entre outros). \ud Palavras-Chave: Bibliotecas digitais; Metadados; Dublin Core.Available for the public access since June 2009, the University of Sao Paulo Brasiliana \ud Digital Library, aims to provide to the research the largest Brasiliana guarded by an \ud University. The purpose is make available online part of the University Collection, as an \ud useful and functional instrument to the research and study of Brazilian themes and culture, \ud and also offer a technological management model able to be disseminated to other collections \ud and institutions. This work shows the results of the implantation of a metadata schema based \ud on Dublin Core format, for the description of rare and special works on the \ud web. Specifically, it shows the content description procedures and processes of several \ud documents typologies (books, journals, images etc) and digital formats (pdf, jpeg and others). \ud Keywords: Digital Libraries, Metadata, Dublin Core

    Semileptonic D->pi/K and B->pi/D decays in 2+1 flavor lattice QCD

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    We present results for form factors of semileptonic decays of DD and BB mesons in 2+1 flavor lattice QCD using the MILC gauge configurations. With an improved staggered action for light quarks, we successfully reduce the systematic error from the chiral extrapolation. The results for DD decays are in agreement with experimental ones. The results for B decays are preliminary. Combining our results with experimental branching ratios, we then obtain the CKM matrix elements Vcd|V_{cd}|, Vcs|V_{cs}|, Vcb|V_{cb}| and Vub|V_{ub}|. We also check CKM unitarity, for the first time, using only lattice QCD as the theoretical input.Comment: Talk presented at Lattice2004(heavy); 3 pages, 3 figure

    Leptonic decay constants f_Ds and f_D in three flavor lattice QCD

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    We determine the leptonic decay constants in three flavor unquenched lattice QCD. We use O(a^2)-improved staggered light quarks and O(a)-improved charm quarks in the Fermilab heavy quark formalism. Our preliminary results, based upon an analysis at a single lattice spacing, are f_Ds = 263(+5-9)(+/-24) MeV and f_D = 225(+11-13)(+/-21) MeV. In each case, the first reported error is statistical while the is the combined systematic uncertainty.Comment: Talk presented at Lattice2004(heavy), Fermilab, June 21-26, 2004. 3 pages, 2 figure

    The effect of extra dimensions on gravity wave bursts from cosmic string cusps

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    We explore the kinematical effect of having extra dimensions on the gravity wave emission from cosmic strings. Additional dimensions both round off cusps, and reduce the probability of their formation. We recompute the gravity wave burst, taking into account these two factors, and find a potentially significant damping on the gravity waves of the strings.Comment: 33 pages, 8 figures, published versio

    Quest for Localized 4-D Black Holes in Brane Worlds

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    We investigate the possibility of obtaining localized black hole solutions in brane worlds by introducing a dependence of the four-dimensional line--element on the extra dimension. An analysis, performed for the cases of an empty bulk and of a bulk containing either a scalar or a gauge field, reveals that no conventional type of matter can support such a dependence. Considering a particular ansatz for the five-dimensional line--element that corresponds to a black hole solution with a ``decaying'' horizon, we determine the bulk energy--momentum tensor capable of sustaining such a behaviour. It turns out that an exotic, shell-like distribution of matter is required. For such solutions, the black hole singularity is indeed localized near the brane and the spacetime is well defined near the AdS horizon, in contrast to the behaviour found in black string type solutions.Comment: 17 pages, RevTex, 3 figures, version to appear in Physical Review D, comments and references added, typos correcte

    A comment on multiple vacua, particle production and the time dependent AdS/CFT correspondence

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    We give an explicit formulation of the time dependent AdS/CFT correspondence when there are multiple vacua present in Lorentzian signature. By computing sample two point functions we show how different amplitudes are related by cosmological particle production. We illustrate our methods in two example spacetimes: (a) a ``bubble of nothing'' in AdS space, and (b) an asymptotically locally AdS spacetime with a bubble of nothing on the boundary. In both cases the alpha vacua of de Sitter space make an interesting appearance.Comment: 9 page

    Inkjet-based biopatterning of bone morphogenetic protein-2 to spatially control calvarial bone formation

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    The purpose of this study was to demonstrate spatial control of osteoblast differentiation in vitro and bone formation in vivo using inkjet bioprinting technology and to create three-dimensional persistent bio-ink patterns of bone morphogenetic protein-2 (BMP-2) and its modifiers immobilized within microporous scaffolds. Semicircular patterns of BMP-2 were printed within circular DermaMatrix™ human allograft scaffold constructs. The contralateral halves of the constructs were unprinted or printed with BMP-2 modifiers, including the BMP-2 inhibitor, noggin. Printed bio-ink pattern retention was validated using fluorescent or 125I-labeled bio-inks. Mouse C2C12 progenitor cells cultured on patterned constructs differentiated in a dose-dependent fashion toward an osteoblastic fate in register to BMP-2 patterns. The fidelity of spatial restriction of osteoblastic differentiation at the boundary between neighboring BMP-2 and noggin patterns improved in comparison with patterns without noggin. Acellular DermaMatrix constructs similarly patterned with BMP-2 and noggin were then implanted into a mouse calvarial defect model. Patterns of bone formation in vivo were comparable with patterned responses of osteoblastic differentiation in vitro. These results demonstrate that three-dimensional biopatterning of a growth factor and growth factor modifier within a construct can direct cell differentiation in vitro and tissue formation in vivo in register to printed patterns. © 2010 Mary Ann Liebert, Inc

    Cosmological Creation of D-branes and anti-D-branes

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    We argue that the early universe may be described by an initial state of space-filling branes and anti-branes. At high temperature this system is stable. At low temperature tachyons appear and lead to a phase transition, dynamics, and the creation of D-branes. These branes are cosmologically produced in a generic fashion by the Kibble mechanism. From an entropic point of view, the formation of lower dimensional branes is preferred and D3D3 brane-worlds are exponentially more likely to form than higher dimensional branes. Virtually any brane configuration can be created from such phase transitions by adjusting the tachyon profile. A lower bound on the number defects produced is: one D-brane per Hubble volume.Comment: 30 pages, 5 eps figures; v2 more references added; v3 section 4 slightly improve

    Viability of Noether symmetry of F(R) theory of gravity

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    Canonization of F(R) theory of gravity to explore Noether symmetry is performed treating R - 6(\frac{\ddot a}{a} + \frac{\dot a^2}{a^2} + \frac{k}{a^2}) = 0 as a constraint of the theory in Robertson-Walker space-time, which implies that R is taken as an auxiliary variable. Although it yields correct field equations, Noether symmetry does not allow linear term in the action, and as such does not produce a viable cosmological model. Here, we show that this technique of exploring Noether symmetry does not allow even a non-linear form of F(R), if the configuration space is enlarged by including a scalar field in addition, or taking anisotropic models into account. Surprisingly enough, it does not reproduce the symmetry that already exists in the literature (A. K. Sanyal, B. Modak, C. Rubano and E. Piedipalumbo, Gen.Relativ.Grav.37, 407 (2005), arXiv:astro-ph/0310610) for scalar tensor theory of gravity in the presence of R^2 term. Thus, R can not be treated as an auxiliary variable and hence Noether symmetry of arbitrary form of F(R) theory of gravity remains obscure. However, there exists in general, a conserved current for F(R) theory of gravity in the presence of a non-minimally coupled scalar-tensor theory (A. K. Sanyal, Phys.Lett.B624, 81 (2005), arXiv:hep-th/0504021 and Mod.Phys.Lett.A25, 2667 (2010), arXiv:0910.2385 [astro-ph.CO]). Here, we briefly expatiate the non-Noether conserved current and cite an example to reveal its importance in finding cosmological solution for such an action, taking F(R) \propto R^{3/2}.Comment: 16 pages, 1 figure. appears in Int J Theoretical Phys (2012
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