6,759 research outputs found

    Strong evidences for a nonextensive behavior of the rotation period in Open Clusters

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    Time-dependent nonextensivity in a stellar astrophysical scenario combines nonextensive entropic indices qKq_{K} derived from the modified Kawaler's parametrization, and qq, obtained from rotational velocity distribution. These qq's are related through a heuristic single relation given by qq0(1Δt/qK)q\approx q_{0}(1-\Delta t/q_{K}), where tt is the cluster age. In a nonextensive scenario, these indices are quantities that measure the degree of nonextensivity present in the system. Recent studies reveal that the index qq is correlated to the formation rate of high-energy tails present in the distribution of rotation velocity. On the other hand, the index qKq_{K} is determined by the stellar rotation-age relationship. This depends on the magnetic field configuration through the expression qK=1+4aN/3q_{K}=1+4aN/3, where aa and NN denote the saturation level of the star magnetic field and its topology, respectively. In the present study, we show that the connection qqKq-q_{K} is also consistent with 548 rotation period data for single main-sequence stars in 11 Open Clusters aged less than 1 Gyr. The value of qKq_{K}\sim 2.5 from our unsaturated model shows that the mean magnetic field topology of these stars is slightly more complex than a purely radial field. Our results also suggest that stellar rotational braking behavior affects the degree of anti-correlation between qq and cluster age tt. Finally, we suggest that stellar magnetic braking can be scaled by the entropic index qq.Comment: 6 pages and 2 figures, accepted to EPL on October 17, 201

    The ρ\rho parameter at three loops and elliptic integrals

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    We describe the analytic calculation of the master integrals required to compute the two-mass three-loop corrections to the ρ\rho parameter. In particular, we present the calculation of the master integrals for which the corresponding differential equations do not factorize to first order. The homogeneous solutions to these differential equations are obtained in terms of hypergeometric functions at rational argument. These hypergeometric functions can further be mapped to complete elliptic integrals, and the inhomogeneous solutions are expressed in terms of a new class of integrals of combined iterative non-iterative nature.Comment: 14 pages Latex, 7 figures, to appear in the Proceedings of "Loops and Legs in Quantum Field Theory - LL 2018", 29 April - 4 May 2018, Po

    A nonextensive insight to the stellar initial mass function

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    the present paper, we propose that the stellar initial mass distributions as known as IMF are best fitted by qq-Weibulls that emerge within nonextensive statistical mechanics. As a result, we show that the Salpeter's slope of \sim2.35 is replaced when a qq-Weibull distribution is used. Our results point out that the nonextensive entropic index qq represents a new approach for understanding the process of the star-forming and evolution of massive stars.Comment: 5 pages, 2 figures, Accepted to EP

    Does e-learning policy drive change in Higher Education?: A case study relating models of organisational change to e-learning implementation

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    Due to the heightened competition introduced by the potential global market and the need for structural changes within organisations delivering e-content, e-learning policy is beginning to take on a more significant role within the context of educational policy per se. For this reason, it is becoming increasingly important to establish what effect such policies have and how they are achieved. This paper addresses this question, illustrating five ways in which change is understood (Fordist, evolutionary, ecological, community of practice and discourse-oriented) and then using this range of perspectives to explore how e-learning policy drives change (both organisational and pedagogic) within a selected higher education institution. The implications of this case are then discussed, and both methodological and pragmatic conclusions are drawn, considering the relative insights offered by the models and ways in which change around e-learning might be supported or promoted

    Statistical stability of equilibrium states for interval maps

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    We consider families of multimodal interval maps with polynomial growth of the derivative along the critical orbits. For these maps Bruin and Todd have shown the existence and uniqueness of equilibrium states for the potential ϕt:xtlogDf(x)\phi_t:x\mapsto-t\log|Df(x)|, for tt close to 1. We show that these equilibrium states vary continuously in the weak^* topology within such families. Moreover, in the case t=1t=1, when the equilibrium states are absolutely continuous with respect to Lebesgue, we show that the densities vary continuously within these families.Comment: More details given and the appendices now incorporated into the rest of the pape

    Measuring Anomalous Couplings in H->WW* Decays at the International Linear Collider

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    Measurement of the Higgs coupling to W-bosons is an important test of our understanding of the electroweak symmetry breaking mechanism. We study the sensitivity of the International Linear Collider (ILC) to the presence of anomalous HW+W- couplings using ZH -> nu nu WW* -> nu nu 4j events. Using an effective Lagrangian approach, we calculate the differential decay rates of the Higgs boson including the effects of new dimension-5 operators. We present a Monte Carlo simulation of events at the ILC, using a full detector simulation based on geant4 and a real event reconstruction chain. Expected constraints on the anomalous couplings are given.Comment: 18 pages, 7 figures, 1 tabl

    Curva de crescimento em altura de fêmeas Nelore, Aberdeen Angus x Nelore, Canchim x Nelore e Simental x nelore nascidas em duas estações do ano.

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    O objetico neste trabalho foi estimar as curvas de crescimento em alturas de fêmeas Nelo (NEL), Aberdeen Angus x Nelore (AN), Canchim X Nelore (CN) e Simental x Nelore (SN), medidas na garupa dos oito aos 90 meses de idade, nascidas em duas estações do ano (primavera ou outono) e submetidas a dois níveis de suplementação alimentar. Os dados foram ajustados pela função de Brody e os efeitos de grupos genético (GG) e tratamento alimentar (TRAT) sobre a curva foram avaliados separadamente por época de nascimento comparando-se um modelo reduzido, que estimou apenas uma curva independente dos efeitos de GG e TRAT, com modelos mais completos que incluíram os efeitos de GG ou de TRAT. Os resultados obtidos reveleram não haver efeito de suplementação alimentar. Os grupos genéticos estudados aparesentaram curvas de crescimento em altura diferentes entre si também para cada época de nascimento
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