1,102 research outputs found

    Effective Polymer Dynamics of D-Dimensional Black Hole Interiors

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    We consider two different effective polymerization schemes applied to D-dimensional, spherically symmetric black hole interiors. It is shown that polymerization of the generalized area variable alone leads to a complete, regular, single-horizon spacetime in which the classical singularity is replaced by a bounce. The bounce radius is independent of rescalings of the homogeneous internal coordinate, but does depend on the arbitrary fiducial cell size. The model is therefore necessarily incomplete. It nonetheless has many interesting features: After the bounce, the interior region asymptotes to an infinitely expanding Kantowski-Sachs spacetime. If the solution is analytically continued across the horizon, the black hole exterior exhibits asymptotically vanishing quantum-corrections due to the polymerization. In all spacetime dimensions except four, the fall-off is too slow to guarantee invariance under Poincare transformations in the exterior asymptotic region. Hence the four-dimensional solution stands out as the only example which satisfies the criteria for asymptotic flatness. In this case it is possible to calculate the quantum-corrected temperature and entropy. We also show that polymerization of both phase space variables, the area and the conformal mode of the metric, generically leads to a multiple horizon solution which is reminiscent of polymerized mini-superspace models of spherically symmetric black holes in Loop Quantum Gravity.Comment: 14 pages, 4 figures. Added discussion about the dependency on auxiliary structures. Matches with the published versio

    Witnessing causal nonseparability

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    Our common understanding of the physical world deeply relies on the notion that events are ordered with respect to some time parameter, with past events serving as causes for future ones. Nonetheless, it was recently found that it is possible to formulate quantum mechanics without any reference to a global time or causal structure. The resulting framework includes new kinds of quantum resources that allow performing tasks - in particular, the violation of causal inequalities - which are impossible for events ordered according to a global causal order. However, no physical implementation of such resources is known. Here we show that a recently demonstrated resource for quantum computation - the quantum switch - is a genuine example of "indefinite causal order". We do this by introducing a new tool - the causal witness - which can detect the causal nonseparability of any quantum resource that is incompatible with a definite causal order. We show however that the quantum switch does not violate any causal nequality.Comment: 15 + 12 pages, 5 figures. Published versio

    Viral MicroRNA Effects on Pathogenesis of Polyomavirus SV40 Infections in Syrian Golden Hamsters

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    Shaojie Zhang, Vojtech Sroller, Preeti Zanwar, Steven J. Halvorson, Nadim J. Ajami, Corey W. Hecksel, Jody L. Swain, Connie Wong, Janet S. Butel, Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas, United States of AmericaChun Jung Chen, Christopher S. Sullivan, Department of Molecular Biosciences, The University of Texas at Austin, Austin, Texas, United States of AmericaJody L. Swain, Center for Comparative Medicine, Baylor College of Medicine, Houston, Texas, United States of AmericaEffects of polyomavirus SV40 microRNA on pathogenesis of viral infections in vivo are not known. Syrian golden hamsters are the small animal model for studies of SV40. We report here effects of SV40 microRNA and influence of the structure of the regulatory region on dynamics of SV40 DNA levels in vivo. Outbred young adult hamsters were inoculated by the intracardiac route with 1×107 plaque-forming units of four different variants of SV40. Infected animals were sacrificed from 3 to 270 days postinfection and viral DNA loads in different tissues determined by quantitative real-time polymerase chain reaction assays. All SV40 strains displayed frequent establishment of persistent infections and slow viral clearance. SV40 had a broad tissue tropism, with infected tissues including liver, kidney, spleen, lung, and brain. Liver and kidney contained higher viral DNA loads than other tissues; kidneys were the preferred site for long-term persistent infection although detectable virus was also retained in livers. Expression of SV40 microRNA was demonstrated in wild-type SV40-infected tissues. MicroRNA-negative mutant viruses consistently produced higher viral DNA loads than wild-type SV40 in both liver and kidney. Viruses with complex regulatory regions displayed modestly higher viral DNA loads in the kidney than those with simple regulatory regions. Early viral transcripts were detected at higher levels than late transcripts in liver and kidney. Infectious virus was detected infrequently. There was limited evidence of increased clearance of microRNA-deficient viruses. Wild-type and microRNA-negative mutants of SV40 showed similar rates of transformation of mouse cells in vitro and tumor induction in weanling hamsters in vivo. This report identified broad tissue tropism for SV40 in vivo in hamsters and provides the first evidence of expression and function of SV40 microRNA in vivo. Viral microRNA dampened viral DNA levels in tissues infected by SV40 strains with simple or complex regulatory regions.This work was supported in part by research grants R01 CA134524 (JSB) and R01 AI077746 (CSS) from the National Institutes of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.Molecular BiosciencesEmail: [email protected]

    On the nature of continuous physical quantities in classical and quantum mechanics

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    Within the traditional Hilbert space formalism of quantum mechanics, it is not possible to describe a particle as possessing, simultaneously, a sharp position value and a sharp momentum value. Is it possible, though, to describe a particle as possessing just a sharp position value (or just a sharp momentum value)? Some, such as Teller (Journal of Philosophy, 1979), have thought that the answer to this question is No -- that the status of individual continuous quantities is very different in quantum mechanics than in classical mechanics. On the contrary, I shall show that the same subtle issues arise with respect to continuous quantities in classical and quantum mechanics; and that it is, after all, possible to describe a particle as possessing a sharp position value without altering the standard formalism of quantum mechanics.Comment: 26 pages, LaTe

    Non-local Correlations are Generic in Infinite-Dimensional Bipartite Systems

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    It was recently shown that the nonseparable density operators for a bipartite system are trace norm dense if either factor space has infinite dimension. We show here that non-local states -- i.e., states whose correlations cannot be reproduced by any local hidden variable model -- are also dense. Our constructions distinguish between the cases where both factor spaces are infinite-dimensional, where we show that states violating the CHSH inequality are dense, and the case where only one factor space is infinite-dimensional, where we identify open neighborhoods of nonseparable states that do not violate the CHSH inequality but show that states with a subtler form of non-locality (often called "hidden" non-locality) remain dense.Comment: 8 pages, RevTe

    Hyperentangled States

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    We investigate a new class of entangled states, which we call 'hyperentangled',that have EPR correlations identical to those in the vacuum state of a relativistic quantum field. We show that whenever hyperentangled states exist in any quantum theory, they are dense in its state space. We also give prescriptions for constructing hyperentangled states that involve an arbitrarily large collection of systems.Comment: 23 pages, LaTeX, Submitted to Physical Review

    Generic Bell correlation between arbitrary local algebras in quantum field theory

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    We prove that for any two commuting von Neumann algebras of infinite type, the open set of Bell correlated states for the two algebras is norm dense. We then apply this result to algebraic quantum field theory -- where all local algebras are of infinite type -- in order to show that for any two spacelike separated regions, there is an open dense set of field states that dictate Bell correlations between the regions. We also show that any vector state cyclic for one of a pair of commuting nonabelian von Neumann algebras is entangled (i.e., nonseparable) across the algebras -- from which it follows that every field state with bounded energy is entangled across any two spacelike separated regions.Comment: Third version; correction in the proof of Proposition

    Franklin D. Roosevelt

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    Landscape Management Challenges on the California Channel Islands

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    Managing for sustained biodiversity and restoration of natural habitat has become increasingly important over the last two decades, first as mitigation for development (especially in wetlands), and , more recently in natural areas. The latter has come about as land managing agencies like the Department of Defense and Bureau of Land Management have seen the need to reverse the impact of past land uses and agencies like the National Park Service and The Nature Conservancy have taken on the responsibility for less-than-pristine lands. On the California Channel Islands, the need for restoring and managing biodiversity is great, but this restoration and management needs to be based on a sound ecological understanding. By conducting surveys, implementing long-term research and monitoring, and by conducting population and community dynamics research, the necessary data to arrive at such an understanding can be obtained. Once management actions have been taken to effect restoration, monitoring needs to be conducted to determine the success of those actions. The need is to gain enough of an understanding of the islands\u27 ecosystems that we can manage to restore, not just populations of native plants and animals, but also the processes of a naturally functioning ecosystem. The challenges that confront this goal are many and include ecology and popUlation biology, conservation ecology, information management, agency mandates and regulations, the need to build constituencies and consensus among disparate groups, financing, and political pressures

    Geology and petrology of the Devils Tower, Missouri Buttes, and Barlow Canyon area, Crook County, Wyoming

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    Field and laboratory investigations were employed to detmine the mode of emplacement and a petrogenetic model for three igneous localities in Crook County, Wyoming: the Devils Tower, the Missouri Buttes, and the Barlow Canyon area. X-ray fluorescence, microprobe data, and optimal analyses iden tify the Missouri Buttes rock as foid-bearing alkali trachyte and anal cime phonolite and the Devils Tower and Barlow Canyon rocks as analcime phonolite. Associated alloclastic breccia with a crystal-charged volcanic glass matrix, surrounding depressions representing collapse of igneous material back into the vent, striking similarity to known volcante necks, and the occurrence of other extrusive volcan1S11\ in the vicinity lead to the conclusion that the Devils Tower and the Missouri Buttes are the erosional remnants of volcanic necks, The Barlow Canyon intrusion is a small laccolith which caused additional folding of an Early Cretaceous dome. Analcime constitutes 10% to 30% of the phonolite in Devils Tower and the Missouri Buttes, and up to 70% of the Barlow Canyon phonolite Calculated analcime unit cell dimensions are a0 =13.736 ± 003A, and reflect a silica-undersaturated composition. Analcime microphenocrysts and some groundlmass analcime are interpreted as primary igneous phases. The remainder of the analcime was magmatically derived from hydrous, sodium-rich fluids. The analcime-liquid stability field indicates a crystallization depth of 18 km to 43 ·km and a temperature of 600° 640°c. Microprobe and x-ray fluorescence data plot along the trachyte phonolite trend and show a differentiation pattern from Missouri Buttes· trachyte to Missouri Buttes and Devils Tower phonolite to Barlow canyon phonolite, Differentiation occurred by fractional crystallization through the mechanisms of flotation and flow differentiation, The rocks in all three localities are intratelluric material which in the Missouri Buttes and Devils Tower has been rapidly pro pelled to the surface by H20 and CO2 pressure
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