620 research outputs found

    System size and beam energy dependence of azimuthal anisotropy from PHENIX

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    We present azimuthal anisotropy measurements in Au+Au and Cu+Cu collisions at sNN\sqrt{s_{NN}} = 62.4 and 200 GeV. Comparison between reaction plane and cumulant v2v_2 measurements in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV show that non-flow contributions, originating mainly from jets, influence the extracted v2v_2 for pTp_T \gtrsim 3.5 GeV/c. Number of constituent quark (NCQ) scaling of v2v_2, when studied as a function of transverse kinetic energy KETKE_T, is seen to hold for Au+Au collisions at sNN\sqrt{s_{NN}} = 62.4 and 200 GeV and for Cu+Cu collisions at sNN\sqrt{s_{NN}} = 200 GeV for KETKE_{T} \lesssim 1 GeV/c. Differential hexadecupole flow v4v_4 seems to exhibit scaling with integral v2v_2 for centrality \le 40% as has been observed for differential v2v_2.Comment: 4 pages, 3 figures, Proceedings of the QM2008 Conference, Jaipur, India February 4-10 200

    Measurement of charm and bottom production in p+p collisions at s\sqrt{s} = 200 GeV at RHIC-PHENIX

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    RHIC-PHENIX has observed a large suppression pattern and azimuthal anisotropy of non-photonic electron at mid-rapidity (η<0.35\mid\eta\mid<0.35) in Au+Au collisions at sNN=200\sqrt{s_{NN}} = 200 GeV. To understand these results and the interaction of heavy quarks in the hot and dense medium, experimental determination of production ratio of charm over bottom is one of the most important topics, since the behavior of bottom may differ from charm in the medium. We measured the ratio of charm over bottom and total cross section of bottom via partial reconstruction of D0^0\toe+^+ K^- νe\nu_e decay in p+p collisions at s=200\sqrt{s} = 200 GeV. Total cross sections of charm and bottom were also measured via di-electron continuum in p+p collisions at s=200\sqrt{s} = 200 GeV.Comment: 4pages, 4figures,coferenc

    Measurements of Cold Nuclear Matter Effects on J/psi in the PHENIX Experiment via Deuteron-Gold Collisions

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    A new calculation of R_{dAu} has been performed using the 2003 d+Au data and the higher-statistics 2005 p+p data. These nuclear modification factors are compared to calculations using nuclear-modified PDFs and a J/psi breakup cross section is extracted. These values are then used to project the cold nuclear matter effects in Au+Au collisions. Additionally, a more data-driven projection is performed.Comment: 4 pages, 6 figures, proceedings for Quark Matter 200

    Measurements of heavy quark production via single leptons at PHENIX

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    The measurement of single leptons from the semi-leptonic decay of heavy-flavor hadrons has long been a means for studying heavy-quark production. PHENIX has measured single muons in pp collisions at forward rapidity and single electrons in both pp and AuAu collisions at mid-rapidity at sqrt(s_NN)=200 GeV. The most recent PHENIX single lepton results are presented in the context of state-of-the-art pQCD calculations. An updated azimuthal anisotropy, v2(pT), measurement for heavy-flavor single electrons in AuAu collisions is also presented.Comment: 4 pages, 4 figures, presented at the 19th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions, "Quark Matter 2008", Jaipur, India, February 4-10, 200

    The eukaryotic leading and lagging strand DNA polymerases are loaded onto primer-ends via separate mechanisms but have comparable processivity in the presence of PCNA

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    Saccharomyces cerevisiae DNA polymerase δ (Pol δ) and DNA polymerase ε (Pol ε) are replicative DNA polymerases at the replication fork. Both enzymes are stimulated by PCNA, although to different levels. To understand why and to explore the interaction with PCNA, we compared Pol δ and Pol ε in physical interactions with PCNA and nucleic acids (with or without RPA), and in functional assays measuring activity and processivity. Using surface plasmon resonance technique, we show that Pol ε has a high affinity for DNA, but a low affinity for PCNA. In contrast, Pol δ has a low affinity for DNA and a high affinity for PCNA. The true processivity of Pol δ and Pol ε was measured for the first time in the presence of RPA, PCNA and RFC on single-stranded DNA. Remarkably, in the presence of PCNA, the processivity of Pol δ and Pol ε on RPA-coated DNA is comparable. Finally, more PCNA molecules were found on the template after it was replicated by Pol ε when compared to Pol δ. We conclude that Pol ε and Pol δ exhibit comparable processivity, but are loaded on the primer-end via different mechanisms

    Highlights from PHENIX - I

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    This contribution highlights recent results from the PHENIX Collaboration at RHIC. It covers global variables, flow and 2--particle correlations. A second contribution in this issue, by T.C.Awes, covers PHENIX results on heavy quarks, leptons and photons.Comment: Contribution to the 2008 Quark Matter Conference, Jaipur India Sumbitted to Journal of Physics G: Nuclear and Particle Physic

    Return to work after a workplace-oriented intervention for patients on sick-leave for burnout - a prospective controlled study

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    <p>Abstract</p> <p>Background</p> <p>In the present study the effect of a workplace-oriented intervention for persons on long-term sick leave for clinical burnout, aimed at facilitating return to work (RTW) by job-person match through patient-supervisor communication, was evaluated. We hypothesised that the intervention group would show a more successful RTW than a control group.</p> <p>Methods</p> <p>In a prospective controlled study, subjects were identified by the regional social insurance office 2-6 months after the first day on sick leave. The intervention group (n = 74) was compared to a control group who had declined participation, being matched by length of sick leave (n = 74). The RTW was followed up, using sick-listing register data, until 1.5 years after the time of intervention.</p> <p>Results</p> <p>There was a linear increase of RTW in the intervention group during the 1.5-year follow-up period, and 89% of subjects had returned to work to some extent at the end of the follow-up period. The increase in RTW in the control group came to a halt after six months, and only 73% had returned to work to some extent at the end of the 1.5-year follow-up.</p> <p>Conclusions</p> <p>We conclude that the present study demonstrated an improvement of long-term RTW after a workplace-oriented intervention for patients on long-term sick leave due to burnout.</p> <p>Trial registration</p> <p>Current Controlled Trials NCT01039168.</p

    Viral trans-factor independent replication of human papillomavirus genomes

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    <p>Abstract</p> <p>Background</p> <p>Papillomaviruses (PVs) establish a persistent infection in the proliferating basal cells of the epithelium. The viral genome is replicated and maintained as a low-copy nuclear plasmid in basal keratinocytes. Bovine and human papillomaviruses (BPV and HPV) are known to utilize two viral proteins; E1, a DNA helicase, and E2, a transcription factor, which have been considered essential for viral DNA replication. However, growing evidence suggests that E1 and E2 are not entirely essential for stable replication of HPV.</p> <p>Results</p> <p>Here we report that multiple HPV16 mutants, lacking either or both E1 and E2 open reading frame (ORFs) and the long control region (LCR), still support extrachromosomal replication. Our data clearly indicate that HPV16 has a mode of replication, independent of viral trans-factors, E1 and E2, which is achieved by origin activity located outside of the LCR.</p

    Transverse-Momentum Dependence of the J/psi Nuclear Modification in d+Au Collisions at sqrt(s_NN)=200 GeV

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    We present measured J/psi production rates in d+Au collisions at sqrt(s_NN) = 200 GeV over a broad range of transverse momentum (p_T=0-14 GeV/c) and rapidity (-2.2<y<2.2). We construct the nuclear-modification factor R_dAu for these kinematics and as a function of collision centrality (related to impact parameter for the R_dAu collision). We find that the modification is largest for collisions with small impact parameters, and observe a suppression (R_dAu<1) for p_T<4 GeV/c at positive rapidities. At negative rapidity we observe a suppression for p_T1) for p_T>2 GeV/c. The observed enhancement at negative rapidity has implications for the observed modification in heavy-ion collisions at high p_T.Comment: 384 authors, 24 pages, 19 figures, 13 tables. Submitted to Phys. Rev. C. Plain text data tables for the points plotted in figures for this and previous PHENIX publications are publicly available at http://www.phenix.bnl.gov/phenix/WWW/info/data/ppg123_data.htm

    The Crystal Structure of the SV40 T-Antigen Origin Binding Domain in Complex with DNA

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    DNA replication is initiated upon binding of “initiators” to origins of replication. In simian virus 40 (SV40), the core origin contains four pentanucleotide binding sites organized as pairs of inverted repeats. Here we describe the crystal structures of the origin binding domain (obd) of the SV40 large T-antigen (T-ag) both with and without a subfragment of origin-containing DNA. In the co-structure, two T-ag obds are oriented in a head-to-head fashion on the same face of the DNA, and each T-ag obd engages the major groove. Although the obds are very close to each other when bound to this DNA target, they do not contact one another. These data provide a high-resolution structural model that explains site-specific binding to the origin and suggests how these interactions help direct the oligomerization events that culminate in assembly of the helicase-active dodecameric complex of T-ag
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