5,958 research outputs found

    The large CP phase in B(s)-anti-B(s) mixing from primary scalar unparticles

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    In this letter we consider the case of primary scalar unparticle contributions to B(d,s) mixing. With particular emphasis on the impact of the recent hint of new physics in the measurement of the B(s) mixing phase, phi(s), we determine the allowed parameter space and impose bounds on the unparticle couplings.Comment: 8 pages, 8 jpeg figures, using pdflatex. Typo corrected, reference adde

    Robust evolution system for Numerical Relativity

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    The paper combines theoretical and applied ideas which have been previously considered separately into a single set of evolution equations for Numerical Relativity. New numerical ingredients are presented which avoid gauge pathologies and allow one to perform robust 3D calculations. The potential of the resulting numerical code is demonstrated by using the Schwarzschild black hole as a test-bed. Its evolution can be followed up to times greater than one hundred black hole masses.Comment: 11 pages, 4 figures; figure correcte

    Anurans Of A Remnant Forest In Urussanga, Santa Catarina, Southern Of Brazil

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    We provide a list of amphibians from a Submontane Forest remnant in Urussanga municipality, Santa Catarina, southern of Brazil. We sampling through visual and acoustic surveys in four distinct sites. Twenty-six species of anurans belonging to nine families were recorded, where nine species were rare, nine abundant, and eight common. Eleven reproductive modes were observed, with exotrophic tadpoles in still water (mode 1) being most frequent mode (38%). The period of highest vocalization activity occurred between October and January. Temperature, rainfall and air humidity were not correlated with the richness and abundance of calling males. Only photoperiod was positively correlated with the abundance of calling males and species richness. © 2016 Check List and Authors.12

    Almost-stationary motions and gauge conditions in General Relativity

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    An almost-stationary gauge condition is proposed with a view to Numerical Relativity applications. The time lines are defined as the integral curves of the timelike solutions of the harmonic almost-Killing equation. This vector equation is derived by a variational principle, by minimizing the deviations from isometry. The corresponding almost-stationary gauge condition allows one to put the field equations in hyperbolic form, both in the free-evolution ADM and in the Z4 formalisms.Comment: Talk presented at the Spanish Relativity Meeting, September 6-10 2005 Revised versio

    Robustness of the Blandford-Znajek mechanism

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    The Blandford-Znajek mechanism has long been regarded as a key ingredient in models attempting to explain powerful jets in AGNs, quasars, blazzars etc. In such mechanism, energy is extracted from a rotating black hole and dissipated at a load at far distances. In the current work we examine the behaviour of the BZ mechanism with respect to different boundary conditions, revealing the mechanism robustness upon variation of these conditions. Consequently, this work closes a gap in our understanding of this important scenario.Comment: 7 pages, accepted in CQ

    Dynamics of Gravitational Waves in 3D: Formulations, Methods, and Tests

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    The dynamics of gravitational waves is investigated in full 3+1 dimensional numerical relativity, emphasizing the difficulties that one might encounter in numerical evolutions, particularly those arising from non-linearities and gauge degrees of freedom. Using gravitational waves with amplitudes low enough that one has a good understanding of the physics involved, but large enough to enable non-linear effects to emerge, we study the coupling between numerical errors, coordinate effects, and the nonlinearities of the theory. We discuss the various strategies used in identifying specific features of the evolution. We show the importance of the flexibility of being able to use different numerical schemes, different slicing conditions, different formulations of the Einstein equations (standard ADM vs. first order hyperbolic), and different sets of equations (linearized vs. full Einstein equations). A non-linear scalar field equation is presented which captures some properties of the full Einstein equations, and has been useful in our understanding of the coupling between finite differencing errors and non-linearites. We present a set of monitoring devices which have been crucial in our studying of the waves, including Riemann invariants, pseudo-energy momentum tensor, hamiltonian constraint violation, and fourier spectrum analysis.Comment: 34 pages, 14 figure

    Symmetry without Symmetry: Numerical Simulation of Axisymmetric Systems using Cartesian Grids

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    We present a new technique for the numerical simulation of axisymmetric systems. This technique avoids the coordinate singularities which often arise when cylindrical or polar-spherical coordinate finite difference grids are used, particularly in simulating tensor partial differential equations like those of 3+1 numerical relativity. For a system axisymmetric about the z axis, the basic idea is to use a 3-dimensional Cartesian (x,y,z) coordinate grid which covers (say) the y=0 plane, but is only one finite-difference-molecule--width thick in the y direction. The field variables in the central y=0 grid plane can be updated using normal (x,y,z)--coordinate finite differencing, while those in the y \neq 0 grid planes can be computed from those in the central plane by using the axisymmetry assumption and interpolation. We demonstrate the effectiveness of the approach on a set of fully nonlinear test computations in 3+1 numerical general relativity, involving both black holes and collapsing gravitational waves.Comment: 17 pages, 4 figure

    Expression of alternatively spliced human T-cell leukemia virus type 1 mRNAs is influenced by mitosis and by a novel cis-acting regulatory sequence

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    Human T-cell leukemia virus type 1 (HTLV-1) expression depends on the concerted action of Tax, which drives transcription of the viral genome, and Rex, which favors expression of incompletely spliced mRNAs and determines a 2-phase temporal pattern of viral expression. In the present study, we investigated the Rex dependence of the complete set of alternatively spliced HTLV-1 mRNAs. Analyses of cells transfected with Rex-wild-type and Rex-knockout HTLV-1 molecular clones using splice site-specific quantitative reverse transcription (qRT)-PCR revealed that mRNAs encoding the p30Tof, p13, and p12/8 proteins were Rex dependent, while the p21rex mRNA was Rex independent. These findings provide a rational explanation for the intermediate-late temporal pattern of expression of the p30tof, p13, and p12/8 mRNAs described in previous studies. All the Rex-dependent mRNAs contained a 75-nucleotide intronic region that increased the nuclear retention and degradation of a reporter mRNA in the absence of other viral sequences. Selective 2'-hydroxyl acylation analyzed by primer extension (SHAPE) analysis revealed that this sequence formed a stable hairpin structure. Cell cycle synchronization experiments indicated that mitosis partially bypasses the requirement for Rex to export Rex-dependent HTLV-1 transcripts. These findings indicate a link between the cycling properties of the host cell and the temporal pattern of viral expression/latency that might influence the ability of the virus to spread and evade the immune system

    The Physics of Heavy Flavours at SuperB

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    This is a review of the SuperB project, covering the accelerator, detector, and highlights of the broad physics programme. SuperB is a flavour factory capable of performing precision measurements and searches for rare and forbidden decays of Bu,d,sB_{u,d,s}, DD, Ď„\tau and ÎĄ(nS)\Upsilon({\mathrm{nS}}) particles. These results can be used to test fundamental symmetries and expectations of the Standard Model, and to constrain many different hypothesised types of new physics. In some cases these measurements can be used to place constraints on the existence of light dark matter and light Higgs particles with masses below 10GeV/c210GeV/c^2. The potential impact of the measurements that will be made by SuperB on the field of high energy physics is also discussed in the context of data taken at both high energy in the region around the \Upsilon({\mathrm{4S}})$, and near charm threshold.Comment: 49 pages, topical review submitted to J. Phys
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