3,277 research outputs found

    Data analysis of gravitational-wave signals from spinning neutron stars. V. A narrow-band all-sky search

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    We present theory and algorithms to perform an all-sky coherent search for periodic signals of gravitational waves in narrow-band data of a detector. Our search is based on a statistic, commonly called the F\mathcal{F}-statistic, derived from the maximum-likelihood principle in Paper I of this series. We briefly review the response of a ground-based detector to the gravitational-wave signal from a rotating neuron star and the derivation of the F\mathcal{F}-statistic. We present several algorithms to calculate efficiently this statistic. In particular our algorithms are such that one can take advantage of the speed of fast Fourier transform (FFT) in calculation of the F\mathcal{F}-statistic. We construct a grid in the parameter space such that the nodes of the grid coincide with the Fourier frequencies. We present interpolation methods that approximately convert the two integrals in the F\mathcal{F}-statistic into Fourier transforms so that the FFT algorithm can be applied in their evaluation. We have implemented our methods and algorithms into computer codes and we present results of the Monte Carlo simulations performed to test these codes.Comment: REVTeX, 20 pages, 8 figure

    Scaling Exponents in the Incommensurate Phase of the Sine-Gordon and U(1) Thirring Models

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    In this paper we study the critical exponents of the quantum sine-Gordon and U(1) Thirring models in the incommensurate phase. This phase appears when the chemical potential hh exceeds a critical value and is characterized by a finite density of solitons. The low-energy sector of this phase is critical and is described by the Gaussian model (Tomonaga-Luttinger liquid) with the compactification radius dependent on the soliton density and the sine-Gordon model coupling constant β\beta. For a fixed value of β\beta, we find that the Luttinger parameter KK is equal to 1/2 at the commensurate-incommensurate transition point and approaches the asymptotic value β2/8π\beta^2/8\pi away from it. We describe a possible phase diagram of the model consisting of an array of weakly coupled chains. The possible phases are Fermi liquid, Spin Density Wave, Spin-Peierls and Wigner crystal.Comment: 10pages; Improved version; Submitted to Physical Review

    Monitoramento da disseminação genética do rebanho leiteiro no Estado do Acre no período de 2011 a 2012.

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    O governo do Estado do Acre vem incentivando a produção de leite com aplicação de algumas estratégias no setor, dado que tem como base pequenos produtores, com importância significativa para o desenvolvimento do estado. O desenvolvimento sustentável da cadeia produtiva do leite no Estado do Acre é limitado, entre outros fatores, pelo baixo nível tecnológico das propriedades, uso de animais sem aptidão leiteira e tímida utilização de práticas higiênicas no momento da ordenha dos animais (CARNEIRO JÚNIOR et al., 2009), o que se traduz em baixa produção de leite e em produto de baixa qualidade. Há mais de duas décadas que a inseminação artificial foi introduzida no Estado do Acre e sêmen de reprodutores de várias raças de leite já foi utilizado em rebanhos bovinos leiteiros em médias e pequenas propriedades. Este trabalho objetiva conhecer o perfil genético do rebanho de leite de cada município, a fim de que a Embrapa possa criar estratégias para transferência de tecnologias que venham desenvolver o setor produtivo de cada região, conforme o perfil genético do rebanho existente.bitstream/item/118710/1/25445.pd

    Finite-size scaling and the deconfinement transition in gauge theories

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    We introduce a new method for determining the critical indices of the deconfinement transition in gauge theories. The method is based on the finite size scaling behavior of the expectation value of simple lattice operators, such as the plaquette. We test the method for the case of SU(3) pure gauge theory in (2+1) dimensions and obtain a precise determination of the critical index ν\nu, in agreement with the prediction of the Svetitsky-Yaffe conjecture.Comment: 6 pages. Several comments and one reference added, results unchange

    Automated Ecological Assessment of Physical Activity: Advancing Direct Observation.

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    Technological advances provide opportunities for automating direct observations of physical activity, which allow for continuous monitoring and feedback. This pilot study evaluated the initial validity of computer vision algorithms for ecological assessment of physical activity. The sample comprised 6630 seconds per camera (three cameras in total) of video capturing up to nine participants engaged in sitting, standing, walking, and jogging in an open outdoor space while wearing accelerometers. Computer vision algorithms were developed to assess the number and proportion of people in sedentary, light, moderate, and vigorous activity, and group-based metabolic equivalents of tasks (MET)-minutes. Means and standard deviations (SD) of bias/difference values, and intraclass correlation coefficients (ICC) assessed the criterion validity compared to accelerometry separately for each camera. The number and proportion of participants sedentary and in moderate-to-vigorous physical activity (MVPA) had small biases (within 20% of the criterion mean) and the ICCs were excellent (0.82-0.98). Total MET-minutes were slightly underestimated by 9.3-17.1% and the ICCs were good (0.68-0.79). The standard deviations of the bias estimates were moderate-to-large relative to the means. The computer vision algorithms appeared to have acceptable sample-level validity (i.e., across a sample of time intervals) and are promising for automated ecological assessment of activity in open outdoor settings, but further development and testing is needed before such tools can be used in a diverse range of settings

    Standards for evidence in policy decision-making

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    Monitoramento da disseminação genética do rebanho leiteiro no estado do Acre no período de 2009 a 2010 .

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    O objetivo deste trabalho é conhecer o perfil genético do rebanho de leite de cada município, para que a Embrapa possa criar estratégias voltadas à aplicação de tecnologias que venham desenvolver o setor produtivo da região.bitstream/item/56658/1/24133.PD

    Instanton classical solutions of SU(3) fixed point actions on open lattices

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    We construct instanton-like classical solutions of the fixed point action of a suitable renormalization group transformation for the SU(3) lattice gauge theory. The problem of the non-existence of one-instantons on a lattice with periodic boundary conditions is circumvented by working on open lattices. We consider instanton solutions for values of the size (0.6-1.9 in lattice units) which are relevant when studying the SU(3) topology on coarse lattices using fixed point actions. We show how these instanton configurations on open lattices can be taken into account when determining a few-couplings parametrization of the fixed point action.Comment: 23 pages, LaTeX, 4 eps figures, epsfig.sty; some comments adde

    AdS/QCD and its Holographic Light-Front Partonic Representation

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    Starting from the Hamiltonian equation of motion in QCD we find a single variable light-front equation for QCD which determines the eigenspectrum and the light-front wavefunctions of hadrons for general spin and orbital angular momentum. This light-front wave equation is equivalent to the equations of motion which describe the propagation of spin-JJ modes on anti-de Sitter (AdS) space.Comment: 5 pages, 1 figure. Presented by GdT at Diffraction 2008, International Workshop on Diffraction in High Energy Physic

    Thermodynamics of Four-Flavour QCD with Improved Staggered Fermions

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    We have calculated the pressure and energy density in four-flavour QCD using improved fermion and gauge actions. We observe a strong reduction of finite cut-off effects in the high temperature regime, similar to what has been noted before for the SU(3) gauge theory. Calculations have been performed on 163×416^3\times 4 and 16^4 lattices for two values of the quark mass, ma=0.05ma = 0.05 and 0.1. A calculation of the string tension at zero temperature yields a critical temperature Tc/σ=0.407±0.010T_c/\sqrt{\sigma} = 0.407 \pm 0.010 for the smaller quark mass value.Comment: 12 pages, LaTeX2e File, 11 encapsulated postscript file
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