1,529 research outputs found

    Cross Saharan transport of water vapour via recycled cold-pool outflows from moist convection

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    Very sparse data has previously limited observational studies of meteorological processes in the Sahara. We present an observed case of convectively-driven water vapour transport crossing the Sahara over 2.5 days in June 2012, from the Sahel in the south to the Atlas in the north. A daily cycle is observed, with deep convection in the evening generating moist cold pools that fed the next day’s convection; the convection then generated new cold pools, providing a vertical recycling of moisture. Trajectories driven by analyses were able to capture the direction of the transport but not its full extent, particularly at night when cold pools are most active, and analyses missed much of the water content of cold pools. The results highlight the importance of cold pools for moisture transport, dust and clouds, and demonstrate the need to include these processes in models in order to improve the representation of Saharan atmospher

    Energy dependence of exclusive J/ψJ/\psi photoproduction off protons in ultra-peripheral p-Pb collisions at sNN\sqrt{s_{\rm{NN}}} = 5.02 TeV

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    The ALICE Collaboration has measured the energy dependence of exclusive photoproduction of J/ψJ/\psi vector mesons off proton targets in ultra-peripheral p-Pb collisions at a centre-of-mass energy per nucleon pair sNN=5.02\sqrt{s_{\rm NN}} = 5.02 TeV. The e+^+e^- and μ+μ\mu^+\mu^- decay channels are used to measure the cross section as a function of the rapidity of the J/ψJ/\psi in the range 2.5<y<2.7-2.5 < y < 2.7, corresponding to an energy in the γ\gammap centre-of-mass in the interval 40<Wγp<55040 < W_{\gamma\mathrm{p}}<550 GeV. The measurements, which are consistent with a power law dependence of the exclusive J/ψJ/\psi photoproduction cross section, are compared to previous results from HERA and the LHC and to several theoretical models. They are found to be compatible with previous measurements.Comment: 25 pages, 3 captioned figures, 3 tables, authors from page 19, published version, figures at http://alice-publications.web.cern.ch/node/455

    First measurement of Ξc0\Xi_{\rm c}^0 production in pp collisions at s\mathbf{\sqrt{s}} = 7 TeV

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    The production of the charm-strange baryon Ξc0\Xi_{\rm c}^0 is measured for the first time at the LHC via its semileptonic decay into e+Ξνe^+\Xi^-\nu_{\rm e} in pp collisions at s=7\sqrt{s}=7 TeV with the ALICE detector. The transverse momentum (pTp_{\rm T}) differential cross section multiplied by the branching ratio is presented in the interval 1 << pTp_{\rm T} << 8 GeV/cc at mid-rapidity, y|y| << 0.5. The transverse momentum dependence of the Ξc0\Xi_{\rm c}^0 baryon production relative to the D0^0 meson production is compared to predictions of event generators with various tunes of the hadronisation mechanism, which are found to underestimate the measured cross-section ratio.Comment: 22 pages, 6 captioned figures, 1 table, authors from page 17, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/412

    Constraining the magnitude of the Chiral Magnetic Effect with Event Shape Engineering in Pb-Pb collisions at sNN\sqrt{s_{\rm NN}} = 2.76$ TeV

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    In ultrarelativistic heavy-ion collisions, the event-by-event variation of the elliptic flow v2v_2 reflects fluctuations in the shape of the initial state of the system. This allows to select events with the same centrality but different initial geometry. This selection technique, Event Shape Engineering, has been used in the analysis of charge-dependent two- and three-particle correlations in Pb-Pb collisions at sNN=2.76\sqrt{s_{_{\rm NN}}} =2.76 TeV. The two-particle correlator cos(φαφβ)\langle \cos(\varphi_\alpha - \varphi_\beta) \rangle, calculated for different combinations of charges α\alpha and β\beta, is almost independent of v2v_2 (for a given centrality), while the three-particle correlator cos(φα+φβ2Ψ2)\langle \cos(\varphi_\alpha + \varphi_\beta - 2\Psi_2) \rangle scales almost linearly both with the event v2v_2 and charged-particle pseudorapidity density. The charge dependence of the three-particle correlator is often interpreted as evidence for the Chiral Magnetic Effect (CME), a parity violating effect of the strong interaction. However, its measured dependence on v2v_2 points to a large non-CME contribution to the correlator. Comparing the results with Monte Carlo calculations including a magnetic field due to the spectators, the upper limit of the CME signal contribution to the three-particle correlator in the 10-50% centrality interval is found to be 26-33% at 95% confidence level.Comment: 20 pages, 6 captioned figures, 1 tables, authors from page 15, published version, figures at http://aliceinfo.cern.ch/ArtSubmission/node/382

    Risk-factors associated with extremely high cardiovascular risk of mid- and long-term mortality following myocardial infarction: An analysis of the Hyperlipidaemia Therapy in tERtiary Cardiological cEnTer (TERCET) Registry

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    Introduction: Risk-factor identification and risk stratification are prerequisites to the effective primary and secondary prevention of cardiovascular disease (CVD). Patients at the highest risk benefit the most from the intensive risk-factor reduction. However, high-risk patients’ group is heterogeneous, and it is increasingly recognised that there is an 'extreme-risk' category of patients who may require particularly close attention and intensive therapeutic approach. The aim of this study was to identify subgroups of patients at the highest risk of death following myocardial infarction (MI) that might be considered as those at extremely high CVD risk. Methods: We used data from 19,582 participants of the Hyperlipidaemia Therapy in tERtiary Cardiological cEnTer (TERCET) Registry (NCT03065543) of patients with ischaemic heart disease in Poland from 2006-present. Characteristics of 13,052 patients with chronic coronary syndromes (CCS) were compared with those of 4,295 patients with myocardial infarction (STEMI and 48 NSTEMI). Multivariable logistic regression with stepwise backward elimination was used to identify risk factors associated with mortality in the 12-36 months following the index hospitalisation. Results: The mortality rates were significantly higher in patients after MI than in patients with CCS. In the multivariable analysis, the risk factors most strongly associated with 12-month mortality in patients after MI were left ventricular ejection fraction (LVEF) lower than 35% (hazard ratio [HR] 3.83, 95% confidence interval [CI] 3.14-4.67), age >75 years (HR 1.91, 95%CI 1.55-2.35), multivessel coronary artery disease (HR 1.61, 95%CI 1.30-1.99), atrial fibrillation (HR 1.53, 95%CI 55 1.21-1.94) diabetes mellitus (HR 1.35, 95%CI 1.11-1.64) and increased LDL-C (HR per 1 mmol/l 56 1.09, 95%CI 1.01-1.19) or creatinine levels (HR per 10 µmol/L 1.04, 95% CI 1.04-1.05). The risk factors that influenced mortality after 24-36 months were consistent with those after 12 months, with additional low haemoglobin (20-25% risk increase per 1 mmol reduction) and chronic obstructive pulmonary disease (65% risk increase after 36 months). Conclusions: In our large, single-centre real-world analysis we identified the patients with the highest risk of death who could probably benefit the most from the most intensive therapy, and hence should be considered to be an 'extreme risk' population

    Measurement of the production of charm jets tagged with D0^{0} mesons in pp collisions at s\sqrt{s}= 7 TeV

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    The production of charm jets in proton-proton collisions at a center-of-mass energy of s=7\sqrt{s}=7 TeV was measured with the ALICE detector at the CERN Large Hadron Collider. The measurement is based on a data sample corresponding to a total integrated luminosity of 6.236.23 nb1{\rm nb}^{-1}, collected using a minimum-bias trigger. Charm jets are identified by the presence of a D0^0 meson among their constituents. The D0^0 mesons are reconstructed from their hadronic decay D0^0\rightarrowKπ+^{-}\pi^{+}. The D0^0-meson tagged jets are reconstructed using tracks of charged particles (track-based jets) with the anti-kTk_{\mathrm{T}} algorithm in the jet transverse momentum range 5<pT,jetch<305<p_{\rm{T,jet}}^{\mathrm{ch}}<30 GeV/c{\rm GeV/}c and pseudorapidity ηjet<0.5|\eta_{\rm jet}|<0.5. The fraction of charged jets containing a D0^0-meson increases with pT,jetchp_{\rm{T,jet}}^{\rm{ch}} from 0.042±0.004(stat)±0.006(syst)0.042 \pm 0.004\, \mathrm{(stat)} \pm 0.006\, \mathrm{(syst)} to 0.080±0.009(stat)±0.008(syst)0.080 \pm 0.009\, \rm{(stat)} \pm 0.008\, \rm{(syst)}. The distribution of D0^0-meson tagged jets as a function of the jet momentum fraction carried by the D0^0 meson in the direction of the jet axis (zchz_{||}^{\mathrm{ch}}) is reported for two ranges of jet transverse momenta, 5<pT,jetch<155<p_{\rm{T,jet}}^{\rm{ch}}<15 GeV/c{\rm GeV/}c and 15<pT,jetch<3015<p_{\rm{T,jet}}^{\rm{ch}}<30 GeV/c{\rm GeV/}c in the intervals 0.2<zch<1.00.2<z_{||}^{\rm{ch}}<1.0 and 0.4<zch<1.00.4<z_{||}^{\rm{ch}}<1.0, respectively. The data are compared with results from Monte Carlo event generators (PYTHIA 6, PYTHIA 8 and Herwig 7) and with a Next-to-Leading-Order perturbative Quantum Chromodynamics calculation, obtained with the POWHEG method and interfaced with PYTHIA 6 for the generation of the parton shower, fragmentation, hadronisation and underlying event.Comment: 29 pages, 8 captioned figures, 3 tables, authors from page 24, published version, figures at http://alice-publications.web.cern.ch/node/525

    Heavy-flavour and quarkonium production in the LHC era: from proton-proton to heavy-ion collisions

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    This report reviews the study of open heavy-flavour and quarkonium production in high-energy hadronic collisions, as tools to investigate fundamental aspects of Quantum Chromodynamics, from the proton and nucleus structure at high energy to deconfinement and the properties of the Quark-Gluon Plasma. Emphasis is given to the lessons learnt from LHC Run 1 results, which are reviewed in a global picture with the results from SPS and RHIC at lower energies, as well as to the questions to be addressed in the future. The report covers heavy flavour and quarkonium production in proton-proton, proton-nucleus and nucleus-nucleus collisions. This includes discussion of the effects of hot and cold strongly interacting matter, quarkonium photo-production in nucleus-nucleus collisions and perspectives on the study of heavy flavour and quarkonium with upgrades of existing experiments and new experiments. The report results from the activity of the SaporeGravis network of the I3 Hadron Physics programme of the European Union 7th Framework Programme
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