150 research outputs found

    Black Holes Radiate Mainly on the Brane

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    We examine the evaporation of a small black hole on a brane in a world with large extra dimensions. Since the masses of many Kaluza-Klein modes are much smaller than the Hawking temperature of the black hole, it has been claimed that most of the energy is radiated into these modes. We show that this is incorrect. Most of the energy goes into the modes on the brane. This raises the possibility of observing Hawking radiation in future high energy colliders if there are large extra dimensions.Comment: 11 page

    Large N Phases, Gravitational Instantons and the Nuts and Bolts of AdS Holography

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    Recent results in the literature concerning holography indicate that the thermodynamics of quantum gravity (at least with a negative cosmological constant) can be modeled by the large N thermodynamics of quantum field theory. We emphasize that this suggests a completely unitary evolution of processes in quantum gravity, including black hole formation and decay; and even more extreme examples involving topology change. As concrete examples which show that this correspondence holds even when the space-time is only locally asymptotically AdS, we compute the thermodynamical phase structure of the AdS-Taub-NUT and AdS-Taub-Bolt spacetimes, and compare them to a 2+1 dimensional conformal field theory (at large N) compactified on a squashed three sphere, and on the twisted plane.Comment: 20 pages, three figures. (uses harvmac.tex and epsf.tex

    Charged AdS Black Holes and Catastrophic Holography

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    We compute the properties of a class of charged black holes in anti-de Sitter space-time, in diverse dimensions. These black holes are solutions of consistent Einstein-Maxwell truncations of gauged supergravities, which are shown to arise from the inclusion of rotation in the transverse space. We uncover rich thermodynamic phase structures for these systems, which display classic critical phenomena, including structures isomorphic to the van der Waals-Maxwell liquid-gas system. In that case, the phases are controlled by the universal `cusp' and `swallowtail' shapes familiar from catastrophe theory. All of the thermodynamics is consistent with field theory interpretations via holography, where the dual field theories can sometimes be found on the world volumes of coincident rotating branes.Comment: 19 pages, revtex, psfig, 6 multicomponent figures, typos, references and a few remarks have been repaired, and adde

    Black Hole Evaporation and Compact Extra Dimensions

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    We study the evaporation of black holes in space-times with extra dimensions of size L. We first obtain a description which interpolates between the expected behaviors of very large and very small black holes and then show that the luminosity is greatly damped when the horizon shrinks towards L from a larger value. Analogously, black holes born with an initial size smaller than L are almost stable. This effect is due to the dependence of both the Hawking temperature and the grey-body factor of a black hole on the dimensionality of space. Although the picture of what happens when the horizon becomes of size L is still incomplete, we argue that there occurs a (first order) phase transition, possibly signaled by an outburst of energy which leaves a quasi-stable remnant.Comment: RevTeX, 13 pages, 6 figures include

    Genetic risk and a primary role for cell-mediated immune mechanisms in multiple sclerosis.

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    Multiple sclerosis is a common disease of the central nervous system in which the interplay between inflammatory and neurodegenerative processes typically results in intermittent neurological disturbance followed by progressive accumulation of disability. Epidemiological studies have shown that genetic factors are primarily responsible for the substantially increased frequency of the disease seen in the relatives of affected individuals, and systematic attempts to identify linkage in multiplex families have confirmed that variation within the major histocompatibility complex (MHC) exerts the greatest individual effect on risk. Modestly powered genome-wide association studies (GWAS) have enabled more than 20 additional risk loci to be identified and have shown that multiple variants exerting modest individual effects have a key role in disease susceptibility. Most of the genetic architecture underlying susceptibility to the disease remains to be defined and is anticipated to require the analysis of sample sizes that are beyond the numbers currently available to individual research groups. In a collaborative GWAS involving 9,772 cases of European descent collected by 23 research groups working in 15 different countries, we have replicated almost all of the previously suggested associations and identified at least a further 29 novel susceptibility loci. Within the MHC we have refined the identity of the HLA-DRB1 risk alleles and confirmed that variation in the HLA-A gene underlies the independent protective effect attributable to the class I region. Immunologically relevant genes are significantly overrepresented among those mapping close to the identified loci and particularly implicate T-helper-cell differentiation in the pathogenesis of multiple sclerosis

    Microbial degradation of furanic compounds: biochemistry, genetics, and impact

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    Microbial metabolism of furanic compounds, especially furfural and 5-hydroxymethylfurfural (HMF), is rapidly gaining interest in the scientific community. This interest can largely be attributed to the occurrence of toxic furanic aldehydes in lignocellulosic hydrolysates. However, these compounds are also widespread in nature and in human processed foods, and are produced in industry. Although several microorganisms are known to degrade furanic compounds, the variety of species is limited mostly to Gram-negative aerobic bacteria, with a few notable exceptions. Furanic aldehydes are highly toxic to microorganisms, which have evolved a wide variety of defense mechanisms, such as the oxidation and/or reduction to the furanic alcohol and acid forms. These oxidation/reduction reactions constitute the initial steps of the biological pathways for furfural and HMF degradation. Furfural degradation proceeds via 2-furoic acid, which is metabolized to the primary intermediate 2-oxoglutarate. HMF is converted, via 2,5-furandicarboxylic acid, into 2-furoic acid. The enzymes in these HMF/furfural degradation pathways are encoded by eight hmf genes, organized in two distinct clusters in Cupriavidus basilensis HMF14. The organization of the five genes of the furfural degradation cluster is highly conserved among microorganisms capable of degrading furfural, while the three genes constituting the initial HMF degradation route are organized in a highly diverse manner. The genetic and biochemical characterization of the microbial metabolism of furanic compounds holds great promises for industrial applications such as the biodetoxifcation of lignocellulosic hydrolysates and the production of value-added compounds such as 2,5-furandicarboxylic acid

    VizieR Online Data Catalog: XMM-Newton Serendipitous Source Catalogue 3XMM-DR5 (XMM-SSC, 2016)

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    The 3XMM-DR5 catalogue is the third generation catalog of serendipitous X-ray sources from the European Space Agency's (ESA) XMM-Newton observatory, and has been created by the XMM-Newton Survey Science Centre (SSC) on behalf of ESA. The catalog has 354 more observations and 34701 more detections than the preceding 3XMM-DR4 catalog, which was made public in July 2013. The history of the versions can be summarized as: ------------ Name DR# Designation Year Cat. #Sources 2XMMp 0 2XMMp-DR0 2006 2XMM 1 2XMM-DR1 2007 IX/39 191870 2XMMi 2 2XMMi-DR2 2008 IX/40 221012 2XMMi-DR3 3 2XMMi-DR3 2010 IX/41 262902 3XMM-DR4 4 3XMM 2013 IX/44 372728 3XMM-DR5 5 3XMM 2016 IX/46 396910 The production and content of the 3XMM catalogue is described in the the 3XMM-DR4 User Guide at http://xmmssc.irap.omp.eu/Catalogue/3XMM-DR5/3XMM-DR5CatalogueUser_Guide.html The "slim" version of the catalogue (file "xmm3r5s.dat") contains one row per unique source, while the the main catalogue has one row per detection. This slim version includes 44 columns, essentially those containing information about the unique sources, while the full catalogue (file "xmm3r5.fit") describes all detections with 323 columns. The slim version also contains a column with links to the summary pages in the IRAP catalogue archive. In the case of sources with multiple detections the summary page of the best detection is selected (i.e., the detection with the largest exposure time, summed over all cameras), and the summary page gives cross-links to the other detections. A separate file "summary.dat" contains the key details about the observations used in the construction of the 3XMM-DR5 catalogue. (3 data files)

    VizieR Online Data Catalog: XMM-Newton Serendipitous Source Catalogue 3XMM-DR6 (XMM-SSC, 2016)

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    The 3XMM-DR6 catalogue contains source detections drawn from 9160 XMM-Newton EPIC observations, covering an energy interval from 0.2keV to 12keV. These observations were made between 2000 February 3 and 2015 June 4 and all datasets were publicly available by 2016 January 31, but not all public observations are included in this catalogue (see below for more information). Should you use the catalogue for your research and publish the results, please use the acknowledgement below and cite the paper describing 3XMM (Rosen, Webb, Watson et al., 2016A&A...590A...1R). This research has made use of data obtained from the 3XMM XMM-Newton serendipitous source catalogue compiled by the 10 institutes of the XMM-Newton Survey Science Centre selected by ESA. The following table gives an overview of the statistics of the catalogue in comparison with the 3XMM-DR4 catalogue. - 3XMM-DR6 3XMM-DR5 Increment Number of observations 9160 7781 1379 Number of 'clean' observations (i.e., observation class =1ks exposure) 982sq.deg 877sq.deg 105sq.deg Number of detections 678680 565962 112718 Number of 'clean' detections (i.e., summary flag -5 5238 4668 570 .The production and content of the 3XMM catalogue is described in the the 3XMM-DR6 User Guide at http://xmmssc.irap.omp.eu/Catalogue/3XMM-DR6/3XMM-DR6CatalogueUser_Guide.html The "slim" version of the catalogue (file "xmm3r6s.dat") contains one row per unique source, while the the main catalogue has one row per detection. This slim version includes 44 columns, essentially those containing information about the unique sources, while the full catalogue (file "xmm3r6.fit") describes all detections with 323 columns. The slim version also contains a column with links to the summary pages in the IRAP catalogue archive. In the case of sources with multiple detections the summary page of the best detection is selected (i.e., the detection with the largest exposure time, summed over all cameras), and the summary page gives cross-links to the other detections. A separate file "summary.dat" contains the key details about the observations used in the construction of the 3XMM-DR6 catalogue. (3 data files)
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