47 research outputs found

    Seven-plus hours of daily sedentary time and the subsequent risk of breast cancer : Japan Multi-Institutional Collaborative Cohort Study

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    This study aimed to investigate the association between daily sedentary time and the risk of breast cancer (BC) in a large Japanese population. The participants were 36,023 women aged 35–69 years from the Japan Multi-Institutional Collaborative Cohort Study. Cox proportional hazards analysis was used to estimate adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) for BC incidence in relation to time spent sedentarily (categorical variables: <7 and ≥7 hours/day [h/d]). Additionally, the associations of BC incidence to the joint effect of sedentary time with each component of physical activity, such as leisure-time metabolic equivalents (METs), frequency of leisure-time physical activity, and daily walking time, were examined. During 315,189 person-years of follow-up, 554 incident cases of BC were identified. When compared to participants who spent <7 h/d sedentary, those who spent ≥7 h/d sedentary have a significantly higher risk of BC (HR, 1.36; 95% CI, 1.07–1.71). The corresponding HRs among participants who spent ≥7 h/d sedentary with more physical activity, such as ≥1 h/d for leisure-time METs, ≥3 days/week of leisure-time physical activity, and ≥1 h/d of daily walking were 1.58 (95% CI, 1.11–2.25), 1.77 (95% CI, 1.20–2.61), and 1.42 (95% CI, 1.10–1.83), respectively, compared with those who spent <7 h/d sedentary. This study found that spending ≥7 h/d of sedentary time is associated with the risk of BC. Neither leisure-time physical activity nor walking had a BC-preventive effect in those with ≥7 h/d of sedentary time

    Single electron yields from semileptonic charm and bottom hadron decays in Au++Au collisions at sNN=200\sqrt{s_{NN}}=200 GeV

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    The PHENIX Collaboration at the Relativistic Heavy Ion Collider has measured open heavy-flavor production in minimum bias Au++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV via the yields of electrons from semileptonic decays of charm and bottom hadrons. Previous heavy-flavor electron measurements indicated substantial modification in the momentum distribution of the parent heavy quarks due to the quark-gluon plasma created in these collisions. For the first time, using the PHENIX silicon vertex detector to measure precision displaced tracking, the relative contributions from charm and bottom hadrons to these electrons as a function of transverse momentum are measured in Au++Au collisions. We compare the fraction of electrons from bottom hadrons to previously published results extracted from electron-hadron correlations in pp++pp collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV and find the fractions to be similar within the large uncertainties on both measurements for pT>4p_T>4 GeV/cc. We use the bottom electron fractions in Au++Au and pp++pp along with the previously measured heavy flavor electron RAAR_{AA} to calculate the RAAR_{AA} for electrons from charm and bottom hadron decays separately. We find that electrons from bottom hadron decays are less suppressed than those from charm for the region 3<pT<43<p_T<4 GeV/cc.Comment: 432 authors, 33 pages, 23 figures, 2 tables, 2011 data. v2 is version accepted for publication by Phys. Rev. C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Measurement of higher cumulants of net-charge multiplicity distributions in Au++Au collisions at sNN=7.7200\sqrt{s_{_{NN}}}=7.7-200 GeV

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    We report the measurement of cumulants (Cn,n=14C_n, n=1\ldots4) of the net-charge distributions measured within pseudorapidity (η<0.35|\eta|<0.35) in Au++Au collisions at sNN=7.7200\sqrt{s_{_{NN}}}=7.7-200 GeV with the PHENIX experiment at the Relativistic Heavy Ion Collider. The ratios of cumulants (e.g. C1/C2C_1/C_2, C3/C1C_3/C_1) of the net-charge distributions, which can be related to volume independent susceptibility ratios, are studied as a function of centrality and energy. These quantities are important to understand the quantum-chromodynamics phase diagram and possible existence of a critical end point. The measured values are very well described by expectation from negative binomial distributions. We do not observe any nonmonotonic behavior in the ratios of the cumulants as a function of collision energy. The measured values of C1/C2=μ/σ2C_1/C_2 = \mu/\sigma^2 and C3/C1=Sσ3/μC_3/C_1 = S\sigma^3/\mu can be directly compared to lattice quantum-chromodynamics calculations and thus allow extraction of both the chemical freeze-out temperature and the baryon chemical potential at each center-of-mass energy.Comment: 512 authors, 8 pages, 4 figures, 1 table. v2 is version accepted for publication in Phys. Rev. C as a Rapid Communication. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Transverse energy production and charged-particle multiplicity at midrapidity in various systems from sNN=7.7\sqrt{s_{NN}}=7.7 to 200 GeV

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    Measurements of midrapidity charged particle multiplicity distributions, dNch/dηdN_{\rm ch}/d\eta, and midrapidity transverse-energy distributions, dET/dηdE_T/d\eta, are presented for a variety of collision systems and energies. Included are distributions for Au++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200, 130, 62.4, 39, 27, 19.6, 14.5, and 7.7 GeV, Cu++Cu collisions at sNN=200\sqrt{s_{_{NN}}}=200 and 62.4 GeV, Cu++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV, U++U collisions at sNN=193\sqrt{s_{_{NN}}}=193 GeV, dd++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV, 3^{3}He++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV, and pp++pp collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV. Centrality-dependent distributions at midrapidity are presented in terms of the number of nucleon participants, NpartN_{\rm part}, and the number of constituent quark participants, NqpN_{q{\rm p}}. For all AA++AA collisions down to sNN=7.7\sqrt{s_{_{NN}}}=7.7 GeV, it is observed that the midrapidity data are better described by scaling with NqpN_{q{\rm p}} than scaling with NpartN_{\rm part}. Also presented are estimates of the Bjorken energy density, εBJ\varepsilon_{\rm BJ}, and the ratio of dET/dηdE_T/d\eta to dNch/dηdN_{\rm ch}/d\eta, the latter of which is seen to be constant as a function of centrality for all systems.Comment: 706 authors, 32 pages, 20 figures, 34 tables, 2004, 2005, 2008, 2010, 2011, and 2012 data. v2 is version accepted for publication in Phys. Rev.

    Measurement of jet-medium interactions via direct photon-hadron correlations in Au++Au and dd++Au collisions at sNN=200\sqrt{s_{_{NN}}}=200 GeV

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    We present direct photon-hadron correlations in 200 GeV/A Au++Au, dd++Au and pp++pp collisions, for direct photon pTp_T from 5--12 GeV/cc, collected by the PHENIX Collaboration in the years from 2006 to 2011. We observe no significant modification of jet fragmentation in dd++Au collisions, indicating that cold nuclear matter effects are small or absent. Hadrons carrying a large fraction of the quark's momentum are suppressed in Au++Au compared to pp++pp and dd++Au. As the momentum fraction decreases, the yield of hadrons in Au++Au increases to an excess over the yield in pp++pp collisions. The excess is at large angles and at low hadron pTp_T and is most pronounced for hadrons associated with lower momentum direct photons. Comparison to theoretical calculations suggests that the hadron excess arises from medium response to energy deposited by jets.Comment: 578 authors from 80 institutions, 11 pages, 7 figures, data from 2007, 2008, 2010, and 2011. v2 is version accepted for publication in Physical Review C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are (or will be) publicly available at http://www.phenix.bnl.gov/papers.htm

    Measurements of identified particle anisotropic flow in Cu plus Au and U plus U collisions by PHENIX experiment

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    Neutral pion and η\eta meson production in proton-proton collisions at s=0.9\sqrt{s}=0.9 TeV and s=7\sqrt{s}=7 TeV

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    The first measurements of the invariant differential cross sections of inclusive π0\pi^0 and η\eta meson production at mid-rapidity in proton-proton collisions at s=0.9\sqrt{s}=0.9 TeV and s=7\sqrt{s}=7 TeV are reported. The π0\pi^0 measurement covers the ranges 0.4<pT<70.4<p_T<7 GeV/cc and 0.3<pT<250.3<p_T<25 GeV/cc for these two energies, respectively. The production of η\eta mesons was measured at s=7\sqrt{s}=7 TeV in the range 0.4<pT<150.4<p_T<15 GeV/cc. Next-to-Leading Order perturbative QCD calculations, which are consistent with the π0\pi^0 spectrum at s=0.9\sqrt{s}=0.9 TeV, overestimate those of π0\pi^0 and η\eta mesons at s=7\sqrt{s}=7 TeV, but agree with the measured η/π0\eta/\pi^0 ratio at s=7\sqrt{s}=7 TeV.Comment: 17 pages, 5 captioned figures, 2 tables, authors from page 12, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/310
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