| 1. |
- Abelev, Betty, et al.
(author)
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Long-range angular correlations on the near and away side in p-Pb collisions at root S-NN=5.02 TeV
- 2013
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In: Physics Letters. Section B: Nuclear, Elementary Particle and High-Energy Physics. - : Elsevier BV. - 0370-2693. ; 719:1-3, s. 29-41
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Journal article (peer-reviewed)abstract
- Angular correlations between charged trigger and associated particles are measured by the ALICE detector in p-Pb collisions at a nucleon-nucleon centre-of-mass energy of 5.02 TeV for transverse momentum ranges within 0.5 < P-T,P-assoc < P-T,P-trig < 4 GeV/c. The correlations are measured over two units of pseudorapidity and full azimuthal angle in different intervals of event multiplicity, and expressed as associated yield per trigger particle. Two long-range ridge-like structures, one on the near side and one on the away side, are observed when the per-trigger yield obtained in low-multiplicity events is subtracted from the one in high-multiplicity events. The excess on the near-side is qualitatively similar to that recently reported by the CMS Collaboration, while the excess on the away-side is reported for the first time. The two-ridge structure projected onto azimuthal angle is quantified with the second and third Fourier coefficients as well as by near-side and away-side yields and widths. The yields on the near side and on the away side are equal within the uncertainties for all studied event multiplicity and p(T) bins, and the widths show no significant evolution with event multiplicity or p(T). These findings suggest that the near-side ridge is accompanied by an essentially identical away-side ridge. (c) 2013 CERN. Published by Elsevier B.V. All rights reserved.
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| 2. |
- Abelev, Betty, et al.
(author)
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Measurement of prompt J/psi and beauty hadron production cross sections at mid-rapidity in pp collisions at root s=7 TeV
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :11
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Journal article (peer-reviewed)abstract
- The ALICE experiment at the LHC has studied J/psi production at mid-rapidity in pp collisions at root s = 7 TeV through its electron pair decay on a data sample corresponding to an integrated luminosity L-int = 5.6 nb(-1). The fraction of J/psi from the decay of long-lived beauty hadrons was determined for J/psi candidates with transverse momentum p(t) > 1,3 GeV/c and rapidity vertical bar y vertical bar < 0.9. The cross section for prompt J/psi mesons, i.e. directly produced J/psi and prompt decays of heavier charmonium states such as the psi(2S) and chi(c) resonances, is sigma(prompt J/psi) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 8.3 +/- 0.8(stat.) +/- 1.1 (syst.)(-1.4)(+1.5) (syst. pol.) mu b. The cross section for the production of b-hadrons decaying to J/psi with p(t) > 1.3 GeV/c and vertical bar y vertical bar < 0.9 is a sigma(J/psi <- hB) (p(t) > 1.3 GeV/c, vertical bar y vertical bar < 0.9) = 1.46 +/- 0.38 (stat.)(-0.32)(+0.26) (syst.) mu b. The results are compared to QCD model predictions. The shape of the p(t) and y distributions of b-quarks predicted by perturbative QCD model calculations are used to extrapolate the measured cross section to derive the b (b) over bar pair total cross section and d sigma/dy at mid-rapidity.
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| 3. |
- Abelev, Betty, et al.
(author)
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Underlying Event measurements in pp collisions at root s=0.9 and 7 TeV with the ALICE experiment at the LHC
- 2012
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In: Journal of High Energy Physics. - 1029-8479. ; :7
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Journal article (peer-reviewed)abstract
- We present measurements of Underlying Event observables in pp collisions at root s = 0 : 9 and 7 TeV. The analysis is performed as a function of the highest charged-particle transverse momentum p(T),L-T in the event. Different regions are defined with respect to the azimuthal direction of the leading (highest transverse momentum) track: Toward, Transverse and Away. The Toward and Away regions collect the fragmentation products of the hardest partonic interaction. The Transverse region is expected to be most sensitive to the Underlying Event activity. The study is performed with charged particles above three different p(T) thresholds: 0.15, 0.5 and 1.0 GeV/c. In the Transverse region we observe an increase in the multiplicity of a factor 2-3 between the lower and higher collision energies, depending on the track p(T) threshold considered. Data are compared to PYTHIA 6.4, PYTHIA 8.1 and PHOJET. On average, all models considered underestimate the multiplicity and summed p(T) in the Transverse region by about 10-30%.
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| 6. |
- Hamilos, Michalis, et al.
(author)
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Relationship between peripheral arterial reactive hyperemia and residual platelet reactivity after 600 mg clopidogrel
- 2011
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In: Journal of Thrombosis and Thrombolysis. - : Springer Science and Business Media LLC. - 0929-5305 .- 1573-742X. ; 32:1, s. 64-71
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Journal article (peer-reviewed)abstract
- Clopidogrel reduces long-term ischemic events in patients with acute coronary syndrome or stable angina (SA) undergoing percutaneous coronary intervention (PCI). Endothelial function improvement has been proposed, among other factors, for this beneficial effect of clopidogrel, but whether this might be associated to its anti-platelet action remains unclear. We tested the hypothesis that clopidogrel improvement of peripheral vascular endothelial function might be associated with inhibition of platelet aggregation. Endothelial function was evaluated before and at least 12 h after 600 mg clopidogrel in 43 SA pts undergoing elective PCI by: (a) reactive hyperemia peripheral arterial tonometry (measuring the Endoscore); (b) circulating endothelial microparticles (EMPs). Response to clopidogrel was measured with point-of-care VerifyNow P2Y12 assay and expressed as platelet reaction unit (PRU) and percent platelet inhibition (%PI). High platelet reactivity after clopidogrel was defined as PRU ≥ 240. Endothelial function improved after clopidogrel in 20 pts. Changes in Endoscore (Δ Endoscore) were significantly correlated with both PRU (r = -0.61, P < 0.001) and %PI (r = 0.57, P < 0.001). Endoscore significantly increased after clopidogrel in pts with PRU < 240 (0.38 ± 0.26 to 0.57 ± 0.33, P < 0.001), but did not in pts with PRU ≥ 240 (0.53 ± 0.31 to 0.40 ± 0.37, P = 0.12). EMPs were also significantly reduced in pts with PRU < 240 (222 [140-593] to 142 [83-371]/μl, P = 0.001), while no changes were observed in pts with PRU ≥ 240 (256 [178-531] to 388 [238-499]/μl, P = 0.55). In patients with stable coronary artery disease, a single 600 mg clopidogrel loading dose improves vascular endothelial function. This improvement is associated with optimal platelet inhibition and it is not observed in patients with post-clopidogrel high platelet reactivity.
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