595 research outputs found

    Reconsidering the black hole final state in Dirac fields

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    We extend Horowitz and Maldacena's proposal about black hole final state to Dirac fields and find that if annihilation of the infalling positrons and the collapsed electrons inside the horizon is considered, then the nonlinear evolution of collapsing quantum state will be avoided. We further propose that annihilation also plays the central role in the process of black hole information escaping in both Dirac and scalar fields. The computation speed of a black hole is also briefly discussed.Comment: 7pages; Phys. Lett. B 2005 (in press

    Incompressible Fluids of the de Sitter Horizon and Beyond

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    There are (at least) two surfaces of particular interest in eternal de Sitter space. One is the timelike hypersurface constituting the lab wall of a static patch observer and the other is the future boundary of global de Sitter space. We study both linear and non-linear deformations of four-dimensional de Sitter space which obey the Einstein equation. Our deformations leave the induced conformal metric and trace of the extrinsic curvature unchanged for a fixed hypersurface. This hypersurface is either timelike within the static patch or spacelike in the future diamond. We require the deformations to be regular at the future horizon of the static patch observer. For linearized perturbations in the future diamond, this corresponds to imposing incoming flux solely from the future horizon of a single static patch observer. When the slices are arbitrarily close to the cosmological horizon, the finite deformations are characterized by solutions to the incompressible Navier-Stokes equation for both spacelike and timelike hypersurfaces. We then study, at the level of linearized gravity, the change in the discrete dispersion relation as we push the timelike hypersurface toward the worldline of the static patch. Finally, we study the spectrum of linearized solutions as the spacelike slices are pushed to future infinity and relate our calculations to analogous ones in the context of massless topological black holes in AdS4_4.Comment: 27 pages, 8 figure

    Future Boundary Conditions in De Sitter Space

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    We consider asymptotically future de Sitter spacetimes endowed with an eternal observatory. In the conventional descriptions, the conformal metric at the future boundary I^+ is deformed by the flux of gravitational radiation. We however impose an unconventional future "Dirichlet" boundary condition requiring that the conformal metric is flat everywhere except at the conformal point where the observatory arrives at I^+. This boundary condition violates conventional causality, but we argue the causality violations cannot be detected by any experiment in the observatory. We show that the bulk-to-bulk two-point functions obeying this future boundary condition are not realizable as operator correlation functions in any de Sitter invariant vacuum, but they do agree with those obtained by double analytic continuation from anti-de Sitter space.Comment: 16 page

    State/Operator Correspondence in Higher-Spin dS/CFT

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    A recently conjectured microscopic realization of the dS4_4/CFT3_3 correspondence relating Vasiliev's higher-spin gravity on dS4_4 to a Euclidean Sp(N)Sp(N) CFT3_3 is used to illuminate some previously inaccessible aspects of the dS/CFT dictionary. In particular it is argued that states of the boundary CFT3_3 on S2S^2 are holographically dual to bulk states on geodesically complete, spacelike R3R^3 slices which terminate on an S2S^2 at future infinity. The dictionary is described in detail for the case of free scalar excitations. The ground states of the free or critical Sp(N)Sp(N) model are dual to dS-invariant plane-wave type vacua, while the bulk Euclidean vacuum is dual to a certain mixed state in the CFT3_3. CFT3_3 states created by operator insertions are found to be dual to (anti) quasinormal modes in the bulk. A norm is defined on the R3R^3 bulk Hilbert space and shown for the scalar case to be equivalent to both the Zamolodchikov and pseudounitary C-norm of the Sp(N)Sp(N) CFT3_3.Comment: 24 page

    Investigating the nature of open science practices across complementary, alternative, and integrative medicine journals: An audit.

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    BackgroundOpen science practices are implemented across many scientific fields to improve transparency and reproducibility in research. Complementary, alternative, and integrative medicine (CAIM) is a growing field that may benefit from adoption of open science practices. The efficacy and safety of CAIM practices, a popular concern with the field, can be validated or refuted through transparent and reliable research. Investigating open science practices across CAIM journals by using the Transparency and Openness Promotion (TOP) guidelines can potentially promote open science practices across CAIM journals. The purpose of this study is to conduct an audit that compares and ranks open science practices adopted by CAIM journals against TOP guidelines laid out by the Center for Open Science (COS).MethodsCAIM-specific journals with titles containing the words "complementary", "alternative" and/or "integrative" were included in this audit. Each of the eight TOP criteria were used to extract open science practices from each of the CAIM journals. Data was summarized by the TOP guideline and ranked using the TOP Factor to identify commonalities and differences in practices across the included journals.ResultsA total of 19 CAIM journals were included in this audit. Across all journals, the mean TOP Factor was 2.95 with a median score of 2. The findings of this study reveal high variability among the open science practices required by journals in this field. Four journals (21%) had a final TOP score of 0, while the total scores of the remaining 15 (79%) ranged from 1 to 8.ConclusionWhile several studies have audited open science practices across discipline-specific journals, none have focused on CAIM journals. The results of this study indicate that CAIM journals provide minimal guidelines to encourage or require authors to adhere to open science practices and there is an opportunity to improve the use of open science practices in the field

    Заболевание тазобедренного сустава у детей с наследственной предрасположенностью: концептуальная модель

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    На основе принципов интегративной медицины, системного подхода с использованием концептуально−логического моделирования разработана единая система представлений о заболеваниях тазобедренного сустава у детей с наследственной предрасположенностью. Показано, что предлагаемый интегративный подход может служить основой для разработки диагностических и прогностических критериев развития суставов и проведения патогенетического хирургического лечения, направленного на ликвидацию или существенное снижение частоты формирования диспластического коксартроза.Based on the principles of integrative medicine, systemic approach with the use of concept of logical modelling, a uniform system of concepts about the diseases of the hip joint in children with hereditary susceptibility was worked out. It was shown that the suggested integrative approach can be used for working out diagnostic and prognostic criteria of joint development and performing pathogenetic surgery aimed at elimination or reduction in the frequency of forming dysplastic coxarthrosis

    Sloan Digital Sky Survey IV: Mapping the Milky Way, Nearby Galaxies, and the Distant Universe

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    We describe the Sloan Digital Sky Survey IV (SDSS-IV), a project encompassing three major spectroscopic programs. The Apache Point Observatory Galactic Evolution Experiment 2 (APOGEE-2) is observing hundreds of thousands of Milky Way stars at high resolution and high signal-to-noise ratios in the near-infrared. The Mapping Nearby Galaxies at Apache Point Observatory (MaNGA) survey is obtaining spatially resolved spectroscopy for thousands of nearby galaxies (median z0.03z\sim 0.03). The extended Baryon Oscillation Spectroscopic Survey (eBOSS) is mapping the galaxy, quasar, and neutral gas distributions between z0.6z\sim 0.6 and 3.5 to constrain cosmology using baryon acoustic oscillations, redshift space distortions, and the shape of the power spectrum. Within eBOSS, we are conducting two major subprograms: the SPectroscopic IDentification of eROSITA Sources (SPIDERS), investigating X-ray AGNs and galaxies in X-ray clusters, and the Time Domain Spectroscopic Survey (TDSS), obtaining spectra of variable sources. All programs use the 2.5 m Sloan Foundation Telescope at the Apache Point Observatory; observations there began in Summer 2014. APOGEE-2 also operates a second near-infrared spectrograph at the 2.5 m du Pont Telescope at Las Campanas Observatory, with observations beginning in early 2017. Observations at both facilities are scheduled to continue through 2020. In keeping with previous SDSS policy, SDSS-IV provides regularly scheduled public data releases; the first one, Data Release 13, was made available in 2016 July
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