728 research outputs found

    Playing with the future: social irrealism and the politics of aesthetics

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    In this paper we wish to explore the political possibilities of video games. Numerous scholars now take seriously the place of popular culture in the remaking of our geographies, but video games still lag behind. For us, this tendency reflects a general response to them as imaginary spaces that are separate from everyday life and 'real' politics. It is this disconnect between abstraction and lived experience that we complicate by defining play as an event of what Brian Massumi calls lived abstraction. We wish to short-circuit the barriers that prevent the aesthetic resonating with the political and argue that through their enactment, video games can animate fantastical futures that require the player to make, and reflect upon, profound ethical decisions that can be antagonistic to prevailing political imaginations. We refer to this as social irrealism to demonstrate that reality can be understood through the impossible and the imagined

    Recent glitches detected in the Crab pulsar

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    From 2000 to 2010, monitoring of radio emission from the Crab pulsar at Xinjiang Observatory detected a total of nine glitches. The occurrence of glitches appears to be a random process as described by previous researches. A persistent change in pulse frequency and pulse frequency derivative after each glitch was found. There is no obvious correlation between glitch sizes and the time since last glitch. For these glitches Δνp\Delta\nu_{p} and Δν˙p\Delta\dot{\nu}_{p} span two orders of magnitude. The pulsar suffered the largest frequency jump ever seen on MJD 53067.1. The size of the glitch is ∼\sim 6.8 ×10−6\times 10^{-6} Hz, ∼\sim 3.5 times that of the glitch occured in 1989 glitch, with a very large permanent changes in frequency and pulse frequency derivative and followed by a decay with time constant ∼\sim 21 days. The braking index presents significant changes. We attribute this variation to a varying particle wind strength which may be caused by glitch activities. We discuss the properties of detected glitches in Crab pulsar and compare them with glitches in the Vela pulsar.Comment: Accepted for publication in Astrophysics & Space Scienc

    Practically Applicable Formal Methods

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    Abstract. Formal methods are considered to be highly expensive. There-fore, they are currently applied almost only in high risk software develop-ment. In this paper, we show that formal techniques can be also efficiently used in standard large-scale applications. We focus on the generation of specifications which state the termination condition of for loops in Java code (expressed as so called Java Modeling Language decreases clauses). We demonstrate that with help of relatively simple techniques it is pos-sible to successfully generate the clauses for almost 80 % of the loops in a number of widely deployed applications. Moreover, it turns out that the remaining 20 % cases contain loops which should be carefully reviewed by software quality assurance personnel. The results show that our tech-nique might be helpful in spreading the usage of formal methods onto typical business software

    Accelerated Cosmological Models in First-Order Non-Linear Gravity

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    The evidence of the acceleration of universe at present time has lead to investigate modified theories of gravity and alternative theories of gravity, which are able to explain acceleration from a theoretical viewpoint without the need of introducing dark energy. In this paper we study alternative gravitational theories defined by Lagrangians which depend on general functions of the Ricci scalar invariant in minimal interaction with matter, in view of their possible cosmological applications. Structural equations for the spacetimes described by such theories are solved and the corresponding field equations are investigated in the Palatini formalism, which prevents instability problems. Particular examples of these theories are also shown to provide, under suitable hypotheses, a coherent theoretical explanation of earlier results concerning the present acceleration of the universe and cosmological inflation. We suggest moreover a new possible Lagrangian, depending on the inverse of sinh(R), which gives an explanation to the present acceleration of the universe.Comment: 23 pages, Revtex4 fil

    Of Bounces, Branes and Bounds

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    Some recent studies have considered a Randall-Sundrum-like brane world evolving in the background of an anti-de Sitter Reissner-Nordstrom black hole. For this scenario, it has been shown that, when the bulk charge is non-vanishing, a singularity-free ``bounce'' universe will always be obtained. However, for the physically relevant case of a de Sitter brane world, we have recently argued that, from a holographic (c-theorem) perspective, such brane worlds may not be physically viable. In the current paper, we reconsider the validity of such models by appealing to the so-called ``causal entropy bound''. In this framework, a paradoxical outcome is obtained: these brane worlds are indeed holographically viable, provided that the bulk charge is not too small. We go on to argue that this new finding is likely the more reliable one.Comment: 15 pages, Revtex; references added and very minor change

    Challenges and Obstacles for a Bouncing Universe in Brane Models

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    A Brane evolving in the background of a charged AdS black-hole displays in general a bouncing behaviour with a smooth transition from a contracting to an expanding phase. We examine in detail the conditions and consequences of this behaviour in various cases. For a cosmological-constant-dominated Brane, we obtain a singularity-free, inflationary era which is shown to be compatible only with an intermediate-scale fundamental Planck mass. For a radiation-dominated Brane, the bouncing behaviour can occur only for background-charge values exceeding those allowed for non-extremal black holes. For a matter-dominated Brane, the black-hole mass affects the proper volume or the expansion rate of the Brane. We also consider the Brane evolving in an asymmetric background of two distinct charged AdS black hole spacetimes being bounded by the Brane and find that, in the case of an empty critical Brane, bouncing behaviour occurs only if the black-hole mass difference is smaller than a certain value. The effects of a Brane curvature term on the bounce at early and late times are also investigated.Comment: 23 pages, Latex file, comments and references added, version to appear in Phys. Rev.

    Global Search for New Physics with 2.0/fb at CDF

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    Data collected in Run II of the Fermilab Tevatron are searched for indications of new electroweak-scale physics. Rather than focusing on particular new physics scenarios, CDF data are analyzed for discrepancies with the standard model prediction. A model-independent approach (Vista) considers gross features of the data, and is sensitive to new large cross-section physics. Further sensitivity to new physics is provided by two additional algorithms: a Bump Hunter searches invariant mass distributions for "bumps" that could indicate resonant production of new particles; and the Sleuth procedure scans for data excesses at large summed transverse momentum. This combined global search for new physics in 2.0/fb of ppbar collisions at sqrt(s)=1.96 TeV reveals no indication of physics beyond the standard model.Comment: 8 pages, 7 figures. Final version which appeared in Physical Review D Rapid Communication

    Observation of Orbitally Excited B_s Mesons

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    We report the first observation of two narrow resonances consistent with states of orbitally excited (L=1) B_s mesons using 1 fb^{-1} of ppbar collisions at sqrt{s} = 1.96 TeV collected with the CDF II detector at the Fermilab Tevatron. We use two-body decays into K^- and B^+ mesons reconstructed as B^+ \to J/\psi K^+, J/\psi \to \mu^+ \mu^- or B^+ \to \bar{D}^0 \pi^+, \bar{D}^0 \to K^+ \pi^-. We deduce the masses of the two states to be m(B_{s1}) = 5829.4 +- 0.7 MeV/c^2 and m(B_{s2}^*) = 5839.7 +- 0.7 MeV/c^2.Comment: Version accepted and published by Phys. Rev. Let

    Shrinking a large dataset to identify variables associated with increased risk of Plasmodium falciparum infection in Western Kenya

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    Large datasets are often not amenable to analysis using traditional single-step approaches. Here, our general objective was to apply imputation techniques, principal component analysis (PCA), elastic net and generalized linear models to a large dataset in a systematic approach to extract the most meaningful predictors for a health outcome. We extracted predictors for Plasmodium falciparum infection, from a large covariate dataset while facing limited numbers of observations, using data from the People, Animals, and their Zoonoses (PAZ) project to demonstrate these techniques: data collected from 415 homesteads in western Kenya, contained over 1500 variables that describe the health, environment, and social factors of the humans, livestock, and the homesteads in which they reside. The wide, sparse dataset was simplified to 42 predictors of P. falciparum malaria infection and wealth rankings were produced for all homesteads. The 42 predictors make biological sense and are supported by previous studies. This systematic data-mining approach we used would make many large datasets more manageable and informative for decision-making processes and health policy prioritization

    Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV

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    Results are presented from a search for a W' boson using a dataset corresponding to 5.0 inverse femtobarns of integrated luminosity collected during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV. The W' boson is modeled as a heavy W boson, but different scenarios for the couplings to fermions are considered, involving both left-handed and right-handed chiral projections of the fermions, as well as an arbitrary mixture of the two. The search is performed in the decay channel W' to t b, leading to a final state signature with a single lepton (e, mu), missing transverse energy, and jets, at least one of which is tagged as a b-jet. A W' boson that couples to fermions with the same coupling constant as the W, but to the right-handed rather than left-handed chiral projections, is excluded for masses below 1.85 TeV at the 95% confidence level. For the first time using LHC data, constraints on the W' gauge coupling for a set of left- and right-handed coupling combinations have been placed. These results represent a significant improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
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