574 research outputs found

    Linear Categorical Marginal Modeling of solicited symptoms in vaccine clinical trials

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    Analysis of the occurrence of adverse events, and in particular of solicited symptoms, following vaccination is often needed for the safety and benefit-risk evaluation of any candidate vaccine, and typically involves taking repeated measurements. In this article, it is shown that Linear Categorical Marginal Models (LCMMs) are well suited to take into account the dependencies in the data arising from the repeated measurements and provide detailed and useful information for comparing safety profiles of different products while remaining relatively easy to interpret. LCMMs are presented and applied to a Phase III clinical trial of a candidate meningococcal pediatric vaccine

    Binary Models for Marginal Independence

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    Log-linear models are a classical tool for the analysis of contingency tables. In particular, the subclass of graphical log-linear models provides a general framework for modelling conditional independences. However, with the exception of special structures, marginal independence hypotheses cannot be accommodated by these traditional models. Focusing on binary variables, we present a model class that provides a framework for modelling marginal independences in contingency tables. The approach taken is graphical and draws on analogies to multivariate Gaussian models for marginal independence. For the graphical model representation we use bi-directed graphs, which are in the tradition of path diagrams. We show how the models can be parameterized in a simple fashion, and how maximum likelihood estimation can be performed using a version of the Iterated Conditional Fitting algorithm. Finally we consider combining these models with symmetry restrictions

    Музичні жанри: класифікаційні проблеми

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    Music genres – one of the main terms of the theoretical music studies and music practice, which reflect àesthetic and regulative constants of the music art. The music genres belong to the most important communicative-semantic basics of the artistic systems. This article is an attempt to figure out regulative basics for the development of the music genre theory

    Measurement of the ATLAS solenoid magnetic field

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    ATLAS is a general purpose detector designed to explore a wide range of physics at the Large Hadron Collider. At the centre of ATLAS is a tracking detector in a 2 T solenoidal magnetic field. This paper describes the machine built to map the field, the data analysis methods, the final results, and their estimated uncertainties. The remotely controlled mapping machine used pneumatic motors with feedback from optical encoders to scan an array of Hall probes over the field volume and log data at more than 20 000 points in a few hours. The data were analysed, making full use of the physical constraints on the field and of our knowledge of the solenoid coil geometry. After a series of small corrections derived from the data itself, the resulting maps were fitted with a function obeying Maxwell's equations. The fit residuals had an r.m.s. less than 0.5 mT and the systematic error on the measurement of track sagitta due to the field uncertainty was estimated to be in the range 0.02 % to 0.12 % depending on the track rapidity

    Revising Neutrino Oscillation Parameter Space With Direct Flavor-Changing Interactions

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    We formulate direct, neutrino flavor-changing interactions in a framework that fits smoothly with the parameterization of two-and three-state mixing of massive neutrino states. We show that even small direct interaction strengths could have important consequences for the interpretation of currently running and proposed oscillation experiments. The oscillation amplitude and the borders of the allowed regions in two-and three-flavor mixing parameter space can be sensitieve to the presence of direct interactions when the transition probability is small. We use extensively the high sensitivity of the NOMAD experiment to illustrate potentially large effects from small, direct flavor violation. In the purely leptonic sector, we find that the clean muon neutrino and electron neutrino beams from a muon collider could provide the sharpest tests of direct flavor violation.Comment: 16 pages, 10 figure

    Shadowing in neutrino deep inelastic scattering and the determination of the strange quark distribution

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    We discuss shadowing corrections to the structure function F2F_2 in neutrino deep-inelastic scattering on heavy nuclear targets. In particular, we examine the role played by shadowing in the comparison of the structure functions F2F_2 measured in neutrino and muon deep inelastic scattering. The importance of shadowing corrections in the determination of the strange quark distributions is explained.Comment: 22 pages, 7 figure

    The Gross--Llewellyn Smith Sum Rule in the Analytic Approach to Perturbative QCD

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    We apply analytic perturbation theory to the Gross--Llewellyn Smith sum rule. We study the Q2Q^2 evolution and the renormalization scheme dependence of the analytic three-loop QCD correction to this sum rule, and demonstrate that the results are practically renormalization scheme independent and lead to rather different Q2Q^2 evolution than the standard perturbative correction possesses.Comment: 17 pages, 9 eps figures, REVTe

    Search for the Lepton Number Violating Process nu_mu-bar e^- -> mu^- nu_e-bar

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    The NuTeV experiment at Fermilab has used a sign-selected neutrino beam to perform a search for the lepton number violating process nu_mu-bar e^- -> mu^- nu_e-bar, and to measure the cross-section of the Standard Model inverse muon decay process nu_mu e^- -> mu^- nu_e. NuTeV measures the inverse muon decay asymptotic cross-section sigma/E to be 13.8 +/- 1.2 +/- 1.4 x 10^-42 cm^2/GeV. The experiment also observes no evidence for lepton number violation and places one of the most restrictive limits on the LNV/IMD cross-section ratio at < 1.7% at 90% C.L. for V-A couplings and < 0.6% for scalar couplings.Comment: 4 pages, 4 figures, 2 tables. Submitted to Physics Review Letter
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