6,930 research outputs found

    Tau Physics from B Factories

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    Some recent τ\tau-physics results are presented from the BaBar and Belle experiments at the SLAC and KEK B factories, which produce copious numbers of τ\tau-lepton pairs. Measurements of the tau mass and lifetime allow to test lepton universality and CPT invariance, while searches for lepton-flavour violation in tau decays are powerful ways to look for physics beyond the Standard Model. In semihadronic, non-strange tau decays, the vector hadronic final state is particularly important in helping determine the hadronic corrections to the anomalous magnetic moment of the muon, while studies of strange final states are the best available ways to measure the CKM matrix element VusV_{\rm us} and the mass of the strange quark.Comment: Presented at Charm 2006, International Workshop on Tau-Charm Physics, June 05-07 2006, Beijing, Chin

    Correction: A correlated topic model of Science

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    Correction to Annals of Applied Statistics 1 (2007) 17--35 [doi:10.1214/07-AOAS114]Comment: Published in at http://dx.doi.org/10.1214/07-AOAS136 the Annals of Applied Statistics (http://www.imstat.org/aoas/) by the Institute of Mathematical Statistics (http://www.imstat.org

    High-dimensional Ising model selection using 1{\ell_1}-regularized logistic regression

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    We consider the problem of estimating the graph associated with a binary Ising Markov random field. We describe a method based on 1\ell_1-regularized logistic regression, in which the neighborhood of any given node is estimated by performing logistic regression subject to an 1\ell_1-constraint. The method is analyzed under high-dimensional scaling in which both the number of nodes pp and maximum neighborhood size dd are allowed to grow as a function of the number of observations nn. Our main results provide sufficient conditions on the triple (n,p,d)(n,p,d) and the model parameters for the method to succeed in consistently estimating the neighborhood of every node in the graph simultaneously. With coherence conditions imposed on the population Fisher information matrix, we prove that consistent neighborhood selection can be obtained for sample sizes n=Ω(d3logp)n=\Omega(d^3\log p) with exponentially decaying error. When these same conditions are imposed directly on the sample matrices, we show that a reduced sample size of n=Ω(d2logp)n=\Omega(d^2\log p) suffices for the method to estimate neighborhoods consistently. Although this paper focuses on the binary graphical models, we indicate how a generalization of the method of the paper would apply to general discrete Markov random fields.Comment: Published in at http://dx.doi.org/10.1214/09-AOS691 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Rodeo: Sparse, greedy nonparametric regression

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    We present a greedy method for simultaneously performing local bandwidth selection and variable selection in nonparametric regression. The method starts with a local linear estimator with large bandwidths, and incrementally decreases the bandwidth of variables for which the gradient of the estimator with respect to bandwidth is large. The method--called rodeo (regularization of derivative expectation operator)--conducts a sequence of hypothesis tests to threshold derivatives, and is easy to implement. Under certain assumptions on the regression function and sampling density, it is shown that the rodeo applied to local linear smoothing avoids the curse of dimensionality, achieving near optimal minimax rates of convergence in the number of relevant variables, as if these variables were isolated in advance.Comment: Published in at http://dx.doi.org/10.1214/009053607000000811 the Annals of Statistics (http://www.imstat.org/aos/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Does Maternal Methadone Dose Correlate with Severity of Intrauterine Growth Restriction in Infants with Neonatal Abstinence Syndrome?

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    Introduction : Previous studies demonstrate a relationship between maternal opioid use during pregnancy and smaller head circumference of infants with neonatal abstinence syndrome (NAS). The goal of this study is to correlate maternal methadone dose and severity of growth restriction in infants with NAS admitted to the neonatal intensive care unit (NICU). Methods: This is a retrospective analysis of infants (≥35 weeks gestation) exposed to in utero methadone, born between August 2006 and May 2018, and admitted to a Philadelphia NICU for medical therapy for NAS. Growth parameters (birth weight, birth length, and birth head circumference) were compared between infants exposed various doses of methadone. The groups were compared using ANOVA, Post-Hoc Tukey, Chi-square and extended Fisher exact tests. Results: A total of 686 infants met the study criteria; 109 in the High dose group, 359 in the Intermediate dose group, and 218 in the Low dose group. There was no significant difference in the use of other drugs or smoking during the pregnancy. Infants exposed to higher doses of methadone displayed significantly smaller head circumferences and lengths at birth. The mean birth weight was similar between the three groups. Discussion: There may be a danger in prescribing high doses of methadone to pregnant mothers, as they may hinder the growth of the infant. We need to conduct more studies investigating how low head circumference and length affect long term developmental outcomes. These findings may help guide physicians toward the optimum dose of methadone for mothers

    Academic-Community Partnerships: Effectiveness Evaluated Beyond the Ivory Walls

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    Community-based participatory research (CBPR) has furthered our understanding of the working principles required for academic-community partnerships to address persistent public health problems. However, little is known about how effective these partnerships have been in eliminating or reducing community-based public health issues. To contribute to the literature in this area, the authors conducted a survey of U.S. schools and programs in public health and community groups working with these academic partners to: (1) identify the most common local public health issues addressed; (2) examine the characteristics of the partnership and the actual or perceived benefits and challenges for each partner; (3) assess the perceived effectiveness of the partnership and their evaluation techniques; and (4) analyze the intent to continue or dissolve the partnership and the associated factors that influence this decision. The authors provide recommendations that can improve the development, functioning, and effectiveness of academic-community collaborations aimed at addressing a variety of public health concerns

    Dalitz plot slope parameters for KπππK \to \pi\pi\pi decays and two particle interference

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    We study the possible distortion of phase-space in the decays KπππK \to \pi \pi \pi, which may result from final state interference among the decay products. Such distortion may influence the values of slope parameters extracted from the Dalitz plot distribution of these decays. We comment on the consequences on the magnitude of violation of the ΔI=1/2\mid \Delta I \mid = 1/2 rule in these decays.Comment: 17 pages, LaTex2e, 6 figures, v2 authors' affiliation modified, to appear in Mod. Phys. Lett.
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