2,273 research outputs found

    From bricks to quasinormal modes: A new perspective on black hole entropy

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    Calculations of black hole entropy based on the counting of modes of a quantum field propagating in a Schwarzschild background need to be regularized in the vicinity of the horizon. To obtain the Bekenstein-Hawking result the short distance cut-off needs to be fixed by hand. In this note we give an argument for obtaining this cut-off in a natural fashion. We do this by modelling the black hole by its set of quasinormal modes. The horizon then becomes a extended region: the quantum ergosphere. The interaction of the quantum ergosphere and the quantum field provides a natural regularization mechanism. The width of the quantum ergosphere provides the right cut-off for the entropy calculation. We arrive at a dual picture of black hole entropy. The entropy of the black hole is given both by the entropy of the quantum field in the bulk and the dynamical degrees of freedom on the horizon.Comment: Honorable Mention in the 2013 Gravity Research Foundation Essay Competitio

    ATLAS RPC commissioning status and cosmic ray test results

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    The muon trigger system of the ATLAS experiment consists of several sub-systems and each of them need to be tested and certified before LHC operation. In the barrel region Resistive Plate Chambers are employed. RPC detector and its level-1 trigger electronics are designed to detect and select high momentum muons with high time resolution and good tracking capability for a total surface of about 4000 m2. The commissioning phase provided an unique opportunity to demonstrate, before LHC start-up, the functionality of the muon trigger components such as detector chambers, level-1 trigger electronics, detector slow control system, data acquisition chain, software and computing. We present the status of ATLAS RPC detector, the problems met during the commissioning and the solutions found and, finally, its performances as obtained by acquiring cosmic rays

    Sharp estimates for the anisotropic torsional rigidity and the principal frequency

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    In this paper we generalize some classical estimates involving the torsional rigidity and the principal frequency of a convex domain to a class of functionals related to some anisotropic non linear operators

    The DSR-deformed relativistic symmetries and the relative locality of 3D quantum gravity

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    Over the last decade there were significant advances in the understanding of quantum gravity coupled to point particles in 3D (2+1-dimensional) spacetime. Most notably it is emerging that the theory can be effectively described as a theory of free particles on a momentum space with anti-deSitter geometry and with noncommutative spacetime coordinates of the type [xÎŒ,xÎœ]=iℏℓΔΌΜρΌΜxρ[x^{\mu},x^{\nu}]=i \hbar \ell \varepsilon^{\mu\nu}_{\phantom{\mu\nu}\rho} x^{\rho}. We here show that the recently proposed relative-locality curved-momentum-space framework is ideally suited for accommodating these structures characteristic of 3D quantum gravity. Through this we obtain an intuitive characterization of the DSR-deformed Poincar\'e symmetries of 3D quantum gravity, and find that the associated relative spacetime locality is of the type producing dual-gravity lensing.Comment: LaTex, 12 pages, 3 figure

    Scalability of Optical Interconnects Based on Microring Resonators

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    This letter investigates the use of optical microring resonators as switching elements (SEs) in large optical interconnection fabrics. We introduce a simple physical-layer model to assess scalability in crossbar- and Benes-based architectures.We also propose a new dilated SE that improves scalability to build fabrics of several terabits per second of aggregate capacit

    Eliciting the Functional Taxonomy from protein annotations and taxa

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    The advances of omics technologies have triggered the production of an enormous volume of data coming from thousands of species. Meanwhile, joint international efforts like the Gene Ontology (GO) consortium have worked to provide functional information for a vast amount of proteins. With these data available, we have developed FunTaxIS, a tool that is the first attempt to infer functional taxonomy (i.e. how functions are distributed over taxa) combining functional and taxonomic information. FunTaxIS is able to define a taxon specific functional space by exploiting annotation frequencies in order to establish if a function can or cannot be used to annotate a certain species. The tool generates constraints between GO terms and taxa and then propagates these relations over the taxonomic tree and the GO graph. Since these constraints nearly cover the whole taxonomy, it is possible to obtain the mapping of a function over the taxonomy. FunTaxIS can be used to make functional comparative analyses among taxa, to detect improper associations between taxa and functions, and to discover how functional knowledge is either distributed or missing. A benchmark test set based on six different model species has been devised to get useful insights on the generated taxonomic rules

    L’Emanuele eucarestia unica nostra via

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    L’incanto dell’Oltre. Dalla Sacra Scrittura alla poesia religiosa di Carlo Betocchi

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    [Italiano]: ll saggio, amplissimo per estensione multidisciplinare, considera il tempo nella sua tridimensionalità (cronologica, cairotica e aionica e, in Betocchi, dinamica, continuata e statica) come forma e vita dello Spirito, ossia come “Incanto dell’Oltre”, ovvero come passaggio dall’ambiguo Disincanto di un soggetto agglutinante di un Ignoto divorante all’Itinerarium in Deum, alla ricerca di un Fondamento Altro, tra il Tempo della Storia e il desiderio dell’Eterno, sulle tracce di Abramo, e ci offre, nella poesia di Betocchi che si fa preghiera, una riflessione teologica sulla creazione, tra fabula e intreccio narrativo, nella dimensione lineare di un tempo teleologico finalmente ritrovato./[English]: The essay, a wide-ranging one due to its multidisciplinary nature, focuses on time in its triple dimension (chronological, kairotic, aionic and, in Betocchi, dynamic, continuous, and static) as shape and life of the Spirit, namely as “the enchantment of the Beyond”, a passage from the ambiguous disenchantment of an agglutinating subject of a devouring Unknown to the Itinerarium in Deum, searching for an Other Foundation, between the Time of History and the wish for the Eternal, in the steps of Abraham. As such, in Betocchi’s poetry as a prayer, it offers a theological reflection on creation, between fabula and narrative plot, within a linear dimension of a teleological time rediscovered at last
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