101
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Azimuthal anisotropy of π⁰ production in Au+Au collisions at sqrt((s)NN)=200 GeV: path-length dependence of jet quenching and the role of initial geometry. PHYSICAL REVIEW LETTERS 2010; 105:142301. [PMID: 21230825 DOI: 10.1103/physrevlett.105.142301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2010] [Indexed: 05/30/2023]
Abstract
We have measured the azimuthal anisotropy of π⁰ production for 1<p(T)<18 GeV/c for Au+Au collisions at sqrt((s)NN)=200 GeV. The observed anisotropy shows a gradual decrease for 3≲p(T)≲7-10 GeV/c, but remains positive beyond 10 GeV/c. The magnitude of this anisotropy is underpredicted, up to at least ∼10 GeV/c, by current perturbative QCD (PQCD) energy-loss model calculations. An estimate of the increase in anisotropy expected from initial-geometry modification due to gluon saturation effects and fluctuations is insufficient to account for this discrepancy. Calculations that implement a path-length dependence steeper than what is implied by current PQCD energy-loss models show reasonable agreement with the data.
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102
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Elliptic and hexadecapole flow of charged hadrons in Au+Au collisions at sq.rt(s(NN))=200 GeV. PHYSICAL REVIEW LETTERS 2010; 105:062301. [PMID: 20867976 DOI: 10.1103/physrevlett.105.062301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2010] [Indexed: 05/29/2023]
Abstract
Differential measurements of the elliptic (v(2)) and hexadecapole (v(4)) Fourier flow coefficients are reported for charged hadrons as a function of transverse momentum (p(T)) and collision centrality or number of participant nucleons (N(part)) for Au+Au collisions at sq.rt(s(NN))=200 GeV. The v(2,4) measurements at pseudorapidity |η|≤0.35, obtained with four separate reaction-plane detectors positioned in the range 1.0<|η|<3.9, show good agreement, indicating the absence of significant Δη-dependent nonflow correlations. Sizable values for v(4)(p(T)) are observed with a ratio v(4)(p(T),N(part))/v(2)(2)(p(T),N(part))≈0.8 for 50≲N(part)≲200, which is compatible with the combined effects of a finite viscosity and initial eccentricity fluctuations. For N(part)≳200 this ratio increases up to 1.7 in the most central collisions.
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103
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Transition in yield and azimuthal shape modification in dihadron correlations in relativistic heavy ion collisions. PHYSICAL REVIEW LETTERS 2010; 104:252301. [PMID: 20867367 DOI: 10.1103/physrevlett.104.252301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2010] [Indexed: 05/29/2023]
Abstract
Hard-scattered parton probes produced in collisions of large nuclei indicate large partonic energy loss, possibly with collective produced-medium response to the lost energy. We present measurements of π^{0} trigger particles at transverse momenta p{T}{t}=4-12 GeV/c and associated charged hadrons (p{T}{a}=0.5-7 GeV/c) vs relative azimuthal angle Δϕ in Au+Au and p+p collisions at sqrt[s{NN}]=200 GeV. The Au+Au distribution at low p{T}{a}, whose shape has been interpreted as a medium effect, is modified for p{T}{t}<7 GeV/c. At higher p{T}{t}, the data are consistent with unmodified or very weakly modified shapes, even for the lowest measured p{T}{a}, which quantitatively challenges some medium response models. The associated yield of hadrons opposing the trigger particle in Au+Au relative to p+p (I{AA}) is suppressed at high p{T} (I{AA}≈0.35-0.5), but less than for inclusive suppression (R{AA}≈0.2).
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104
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Enhanced production of direct photons in Au + Au collisions at square root(S(NN)) = 200 GeV and implications for the initial temperature. PHYSICAL REVIEW LETTERS 2010; 104:132301. [PMID: 20481877 DOI: 10.1103/physrevlett.104.132301] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2008] [Revised: 12/02/2009] [Indexed: 05/29/2023]
Abstract
The production of e+ e- pairs for m(e+ e-)<0.3 GeV/c2 and 1<p(T)<5 GeV/c is measured in p+p and Au+Au collisions at square root(S(NN))=200 GeV. An enhanced yield above hadronic sources is observed. Treating the excess as photon internal conversions, the invariant yield of direct photons is deduced. In central Au+Au collisions, the excess of the direct photon yield over p+p is exponential in transverse momentum, with an inverse slope T=221+/-19(stat)+/-19(syst) MeV. Hydrodynamical models with initial temperatures ranging from T(init) approximately 300-600 MeV at times of approximately 0.6-0.15 fm/c after the collision are in qualitative agreement with the data. Lattice QCD predicts a phase transition to quark gluon plasma at approximately 170 MeV.
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105
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Supercritical biodiesel production and power cogeneration: technical and economic feasibilities. BIORESOURCE TECHNOLOGY 2010; 101:1834-43. [PMID: 19939671 DOI: 10.1016/j.biortech.2009.10.034] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2008] [Revised: 09/28/2009] [Accepted: 10/10/2009] [Indexed: 05/28/2023]
Abstract
An integrated supercritical fluid technology with power cogeneration to produce biodiesel fuels, with no need for the costly separations involved with the conventional technology, is proposed, documented for technical and economic feasibility, and preliminarily designed. The core of the integrated system consists of the transesterification of various triglyceride sources (e.g., vegetable oils and animal fats) with supercritical methanol/ethanol. Part of the reaction products can be combusted by a diesel power generator integrated in the system which, in turn, provides the power needed to pressurize the system and the heat of the exhaust gases necessary in the transesterification step. The latter energy demand can also be satisfied by a fired heater, especially for higher plant capacities. Different versions of this system can be implemented based on the main target of the technology: biodiesel production or diesel engine applications, including power generation. The process options considered for biodiesel fuel production estimate break-even processing costs of biodiesel as low as $0.26/gal ($0.07/L) with a diesel power generator and $0.35/gal ($0.09/L) with a fired heater for a plant capacity of 15,000 gal/day (56,775 L/day). Both are significantly lower than the current processing costs of approximately $0.51/gal ($0.13/L) of biodiesel produced by conventional catalytic methods. A retail cost of biodiesel produced by the proposed method is likely to be competitive with the prices of diesel fuels.
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106
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Double-helicity dependence of jet properties from dihadrons in longitudinally polarizedp+pcollisions ats=200 GeV. Int J Clin Exp Med 2010. [DOI: 10.1103/physrevd.81.012002] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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107
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Metastatic breast cancer deluding as a papular skin rash. Scott Med J 2009. [DOI: 10.1258/rsmsmj.54.4.59b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Dermatological metastases from internal malignancies are relatively less common than other sites. We describe an interesting case of an elderly lady who initially presented with symptomatic normocytic anaemia, and then developed a widespread papular rash over a period of ten days. The rash was found to be metastatic breast cancer.
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108
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Charged Kaon interferometric probes of space-time evolution in Au+Au collisions at sqrt[S(NN)]=200 GeV. PHYSICAL REVIEW LETTERS 2009; 103:142301. [PMID: 19905563 DOI: 10.1103/physrevlett.103.142301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2009] [Indexed: 05/28/2023]
Abstract
Bose-Einstein correlations of charged kaons are used to probe Au+Au collisions at sqrt[S(NN)]=200 GeV and are compared to charged pion probes, which have a larger hadronic scattering cross section. Three-dimensional Gaussian source radii are extracted, along with a one-dimensional kaon emission source function. The centrality dependences of the three Gaussian radii are well described by a single linear function of N(part)1/3 with a zero intercept. Imaging analysis shows a deviation from a Gaussian tail at r greater than or approximately equal to 10 fm, although the bulk emission at lower radius is well described by a Gaussian. The presence of a non-Gaussian tail in the kaon source reaffirms that the particle emission region in a heavy-ion collision is extended, and that similar measurements with pions are not solely due to the decay of long-lived resonances.
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109
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Measurement of bottom versus charm as a function of transverse momentum with electron-hadron correlations in p + p collisions at square root of s = 200 GeV. PHYSICAL REVIEW LETTERS 2009; 103:082002. [PMID: 19792719 DOI: 10.1103/physrevlett.103.082002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2009] [Indexed: 05/28/2023]
Abstract
The momentum distribution of electrons from semileptonic decays of charm and bottom quarks for midrapidity |y|<0.35 in p+p collisions at square root of s=200 GeV is measured by the PHENIX experiment at the Relativistic Heavy Ion Collider over the transverse momentum range 2<pT<7 GeV/c. The ratio of the yield of electrons from bottom to that from charm is presented. The ratio is determined using partial D/D-->e(+/-)K(-/+)X (K unidentified) reconstruction. It is found that the yield of electrons from bottom becomes significant above 4 GeV/c in pT. A fixed-order-plus-next-to-leading-log perturbative quantum chromodynamics calculation agrees with the data within the theoretical and experimental uncertainties. The extracted total bottom production cross section at this energy is sigma(bb)=3.2(-1.1)(+1.2)(stat)(-1.3)(+1.4)(syst)mub.
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110
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Gluon-spin contribution to the proton spin from the double-helicity asymmetry in inclusive pi0 production in polarized p+p collisions at [sqrt]s=200 GeV. PHYSICAL REVIEW LETTERS 2009; 103:012003. [PMID: 19659137 DOI: 10.1103/physrevlett.103.012003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/06/2008] [Indexed: 05/28/2023]
Abstract
The double helicity asymmetry in neutral pion production for pT=1 to 12 GeV/c was measured with the PHENIX experiment to access the gluon-spin contribution, DeltaG, to the proton spin. Measured asymmetries are consistent with zero, and at a theory scale of micro2=4 GeV2 a next to leading order QCD analysis gives DeltaG[0.02,0.3]=0.2, with a constraint of -0.7<DeltaG[0.02,0.3]<0.5 at Deltachi2=9 (approximately 3sigma) for the sampled gluon momentum fraction (x) range, 0.02 to 0.3. The results are obtained using predictions for the measured asymmetries generated from four representative fits to polarized deep inelastic scattering data. We also consider the dependence of the DeltaG constraint on the choice of the theoretical scale, a dominant uncertainty in these predictions.
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111
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Ferritin accumulation under iron scarcity in Drosophila iron cells. Biochimie 2009; 91:1331-4. [PMID: 19465081 DOI: 10.1016/j.biochi.2009.05.003] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2009] [Accepted: 05/07/2009] [Indexed: 10/20/2022]
Abstract
Ferritins are highly stable, multi-subunit protein complexes with iron-binding capacities that reach 4500 iron atoms per ferritin molecule. The strict dependence of cellular physiology on an adequate supply of iron cofactors has likely been a key driving force in the evolution of ferritins as iron storage molecules. The insect intestine has long been known to contain cells that are responsive to dietary iron levels and a specialized group of "iron cells" that always accumulate iron-loaded ferritin, even when no supplementary iron is added to the diet. Here, we further characterize ferritin localization in Drosophila melanogaster larvae raised under iron-enriched and iron-depleted conditions. High dietary iron intake results in ferritin accumulation in the anterior midgut, but also in garland (wreath) cells and in pericardial cells, which together filter the circulating hemolymph. Ferritin is also abundant in the brain, where levels remain unaltered following dietary iron chelation, a treatment that depletes ferritin from the aforementioned tissues. We attribute the stability of ferritin levels in the brain to the function of the blood-brain barrier that may shield this organ from systemic iron fluctuations. Most intriguingly, our dietary manipulations demonstrably iron-depleted the iron cells without a concomitant reduction in their production of ferritin. Therefore, insect iron cells may constitute an exception from the evolutionary norm with respect to iron-dependent ferritin regulation. It will be of interest to decipher both the physiological purpose served and the mechanism employed to untie ferritin regulation from cellular iron levels in this cell type.
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112
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Accuracy of lung tumour measurements on staging MDCT compared to the final pathological tumour size. Lung Cancer 2009. [DOI: 10.1016/s0169-5002(09)70056-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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113
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Suppression pattern of neutral pions at high transverse momentum in Au + Au collisions at sqrt[sNN]=200 GeV and constraints on medium transport coefficients. PHYSICAL REVIEW LETTERS 2008; 101:232301. [PMID: 19113542 DOI: 10.1103/physrevlett.101.232301] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Indexed: 05/27/2023]
Abstract
For Au + Au collisions at 200 GeV, we measure neutral pion production with good statistics for transverse momentum, pT, up to 20 GeV/c. A fivefold suppression is found, which is essentially constant for 5 < pT < 20 GeV/c. Experimental uncertainties are small enough to constrain any model-dependent parametrization for the transport coefficient of the medium, e.g., q in the parton quenching model. The spectral shape is similar for all collision classes, and the suppression does not saturate in Au + Au collisions.
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114
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115
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Onset of pi(0) suppression studied in Cu+Cu collisions at sqrt S NN=22.4, 62.4, and 200 GeV. PHYSICAL REVIEW LETTERS 2008; 101:162301. [PMID: 18999660 DOI: 10.1103/physrevlett.101.162301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2008] [Indexed: 05/27/2023]
Abstract
Neutral pion transverse momentum (p(T)) spectra at midrapidity (|y| less than or approximately 0.35) were measured in Cu+Cu collisions at sqrt[s(NN)]=22.4, 62.4, and 200 GeV. Relative to pi_(0) yields in p+p collisions scaled by the number of inelastic nucleon-nucleon collisions (N(coll) the pi_(0) yields for p(T) more than or approximately 2 GeV/c in central Cu+Cu collisions are suppressed at 62.4 and 200 GeV whereas an enhancement is observed at 22.4 GeV. A comparison with a jet-quenching model suggests that final state parton energy loss dominates in central Cu+Cu collisions at 62.4 and 200 GeV, while the enhancement at 22.4 GeV is consistent with nuclear modifications in the initial state alone.
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116
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Tumor Necrosis Factor-α Production by Alveolar Macrophages During the Early Development of Phosgene-Induced Lung Injury. Inhal Toxicol 2008. [DOI: 10.3109/08958379609005427] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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117
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J/psi production in sqrt s_NN=200 GeV Cu+Cu collisions. PHYSICAL REVIEW LETTERS 2008; 101:122301. [PMID: 18851363 DOI: 10.1103/physrevlett.101.122301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2007] [Indexed: 05/26/2023]
Abstract
Yields for J/psi production in Cu+Cu collisions at sqrt s_NN=200 GeV have been measured over the rapidity range |y|<2.2 and compared with results in p+p and Au+Au collisions at the same energy. The Cu+Cu data offer greatly improved precision over existing Au+Au data for J/psi production in collisions with small to intermediate numbers of participants, in the range where the quark-gluon plasma transition threshold is predicted to lie. Cold nuclear matter estimates based on ad hoc fits to d+Au data describe the Cu+Cu data up to N_part approximately 50, corresponding to a Bjorken energy density of at least 1.5 GeV/fm(3).
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118
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Particle-species dependent modification of jet-induced correlations in Au+Au collisions at sqrt[s_{NN}]=200 GeV. PHYSICAL REVIEW LETTERS 2008; 101:082301. [PMID: 18764605 DOI: 10.1103/physrevlett.101.082301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2007] [Indexed: 05/26/2023]
Abstract
Measurements in Au+Au collisions at sqrt[s_{NN}]=200 GeV of jet correlations for a trigger hadron at intermediate transverse momentum (p_{T,trig}) with associated mesons or baryons at lower p_{T,assoc} indicate strong modification of the away-side jet. The ratio of jet-associated baryons to mesons increases with centrality and p_{T,assoc}. For the most central collisions, the ratio is similar to that for inclusive measurements. This trend is incompatible with in-vacuum fragmentation but could be due to jetlike contributions from correlated soft partons, which recombine upon hadronization.
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119
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Source breakup dynamics in Au + Au collisions at sqrt[s(NN)]=200 GeV via three-dimensional two-pion source imaging. PHYSICAL REVIEW LETTERS 2008; 100:232301. [PMID: 18643489 DOI: 10.1103/physrevlett.100.232301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2007] [Indexed: 05/26/2023]
Abstract
A three-dimensional correlation function obtained from midrapidity, low p(T), pion pairs in central Au+Au collisions at sqrt[s(NN)]=200 GeV is studied. The extracted model-independent source function indicates a long range tail in the directions of the pion pair transverse momentum (out) and the beam (long). A proper breakup time tau(0) ~ 9 fm/c and a mean proper emission duration Delta tau ~ 2 fm/c, leading to sizable emission time differences ({|Delta t(LCM)|} approximately 12 fm/c), are required to allow models to be successfully matched to these tails. The model comparisons also suggest an outside-in "burning" of the emission source reminiscent of many hydrodynamical models.
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120
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Evidential preferences: cultural appropriateness strategies in health communications. HEALTH EDUCATION RESEARCH 2008; 23:549-59. [PMID: 17631608 DOI: 10.1093/her/cym029] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/16/2023]
Abstract
While there is widespread agreement that communication programs and materials will be more effective when they are 'culturally appropriate' for the populations they serve, little is known about how best to achieve this cultural appropriateness. The specific strategies used to realize the potential of culturally appropriate communication take many forms. This paper discusses an approach to assessing and understanding the presentation of statistical information (an evidential strategy) to enhance the perceived relevance of communications targeted to older African American men and women. Formative research on African Americans' attitudes and knowledge of colorectal cancer explored preferences for presentation of statistical data. Focus group interviews elicited participants' (n = 49) thoughts and attitudes on and anticipated behavioral response to five strategies for presenting cancer data and evidence-general, race specific, disparity, social math and framing approximately 5-year probability of death or survival. A description is provided of the application of this approach to the development of a colorectal cancer campaign for African Americans. This strategy may prove useful in understanding and structuring the presentation of targeted cancer evidence that could result in more effective health communication.
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121
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Analysis of HIV variants in blood and semen in serodiscordants by heteroduplex mobility assay. J Int AIDS Soc 2008. [DOI: 10.1186/1758-2652-11-s1-p211] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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122
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Chronic hydrocephalus-induced hypoxia: increased expression of VEGFR-2+ and blood vessel density in hippocampus. Neuroscience 2007; 152:346-59. [PMID: 18262364 DOI: 10.1016/j.neuroscience.2007.11.049] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2007] [Revised: 11/09/2007] [Accepted: 11/29/2007] [Indexed: 12/11/2022]
Abstract
Chronic hydrocephalus (CH) is a neurological disease characterized by increased cerebrospinal fluid volume and pressure that is often associated with impaired cognitive function. By and large, CH is a complex and heterogeneous cerebrospinal fluid (CSF) disorder where the exact site of brain insult is uncertain. Several mechanisms including neural compression, fiber stretch, and local or global hypoxia have been implicated in the underlying pathophysiology of CH. Specifically, the hippocampus, which plays a significant role in memory processing and is in direct contact with expanding CSF ventricles, may be involved. Using our model of chronic hydrocephalus, we quantified the density of vascular endothelial growth factor receptor 2 (VEGFR-2(+)) neurons, glial, endothelial cells, and blood vessels in hippocampal regions CA1, CA2-3, dentate gyrus and hilus using immunohistochemical and stereological methods. Density and %VEGFR-2(+) cell populations were estimated for CH animals (2-3 weeks vs. 12-16 weeks) and surgical controls (SC). Overall, we found approximately six- to eightfold increase in the cellular density of VEGFR-2(+) and more than double blood vessel density (BVd) in the hippocampus of CH compared with SC. There were no significant regional differences in VEGFR-2(+) cellular and BVd expression in the CH group. VEGFR-2(+) and BVds were significantly related to changes in CSF volume (P<or=0.05), and not intracranial pressure (ICP). The %VEGFR-2(+) was significantly greater in CH than SC (P<or=0.05), and was significantly correlated with BVd (P<or=0.05). These results showed that CH elicited a profound increase in VEGFR-2(+) in hippocampus that corresponded to increased BVd. It was unclear whether increased VEGFR-2(+) and blood vessel expression was related to focal compression alone or in combination with global ischemia/hypoxia conditions as previously described. These findings suggest that VEGFR-2 may play an adaptive role in angiogenesis after CH-induced hypoxia. Modulation of vascular endothelial growth factor/VEGFR-2(+) may be important in developing treatments for hypoxic conditions including hydrocephalus and other forms of cerebral ischemia.
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123
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Elliptic flow for phi mesons and (anti)deuterons in Au+Au collisions at square root of sNN=200 GeV. PHYSICAL REVIEW LETTERS 2007; 99:052301. [PMID: 17930746 DOI: 10.1103/physrevlett.99.052301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/14/2007] [Indexed: 05/25/2023]
Abstract
Differential elliptic flow (v(2)) for phi mesons and (anti)deuterons (d)d is measured for Au+Au collisions at square root of sNN=200 GeV. The v(2) for phi mesons follows the trend of lighter pi+/- and K+/- mesons, suggesting that ordinary hadrons interacting with standard hadronic cross sections are not the primary driver for elliptic flow development. The v(2) values for (d)d suggest that elliptic flow is additive for composite particles. This further validation of the universal scaling of v(2) per constituent quark for baryons and mesons suggests that partonic collectivity dominates the transverse expansion dynamics.
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124
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Abstract
BACKGROUND The use of opioids in the long-term management of chronic low-back pain (LBP) appears to be increasing. Despite this trend, the benefits and risks of these medications remain unclear. OBJECTIVES To determine the efficacy of opioids in adults with chronic LBP. SEARCH STRATEGY We electronically searched CENTRAL, CINAHL and PsycINFO to May 2006; MEDLINE and EMBASE to May 2007. We supplemented our search by reviewing references in relevant systematic reviews and identified trials. SELECTION CRITERIA We included randomized or quasi-randomized controlled trials assessing the use of opioids (as monotherapy or in combination with other therapies) for longer than four weeks, in adults with chronic LBP. Studies were included if they compared non-injectable opioids to other treatments. Comparisons between opioids were excluded. DATA COLLECTION AND ANALYSIS Two authors independently assessed methodological quality and extracted data onto a pre-designed form. Results were statistically pooled using RevMan 4.2. We reported on pain and function using standardized mean difference (SMD) with 95% confidence interval (95% CI) and on side effects using absolute risk difference (RD) with 95% CI. MAIN RESULTS We included four trials. Three compared tramadol to placebo. Pooled results revealed that tramadol was more effective than placebo for pain relief, SMD 0.71 (95% CI 0.39 to 1.02), and improving function, SMD 0.17 (95% CI 0.04 to 0.30). The two most common side effects of tramadol were headaches, RD 9% (95% CI 6% to 12%) and nausea, RD 3% (95% CI 0% to 6%). One trial comparing opioids to another analgesic (naproxen) found opioids were statistically significant for relieving pain but not improving function. When re-calculated, the results were not statistically significant for either pain relief (SMD -0.58; 95% CI -1.42 to 0.26) or improving function (SMD -0.06; 95% CI -0.88 to 0.76) . AUTHORS' CONCLUSIONS Despite concerns surrounding the use of opioids for long-term management of chronic LBP, there remain few high-quality trials assessing their efficacy. The trials in this review, although achieving high internal validity scores, were characterized by a lack of generalizability, inadequate description of study populations, poor intention-to treat analysis, and limited interpretation of functional improvement. Based on our results, the benefits of opioids in clinical practice for the long-term management of chronic LBP remains questionable. Therefore, further high-quality studies that more closely simulate clinical practice are needed to assess the usefulness, and potential risks, of opioids for individuals with chronic LBP.
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125
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System size and energy dependence of jet-induced hadron pair correlation shapes in Cu+Cu and Au+Au collisions at square root sNN=200 and 62.4 GeV. PHYSICAL REVIEW LETTERS 2007; 98:232302. [PMID: 17677902 DOI: 10.1103/physrevlett.98.232302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Indexed: 05/16/2023]
Abstract
We present azimuthal angle correlations of intermediate transverse momentum (1-4 GeV/c) hadrons from dijets in Cu+Cu and Au+Au collisions at square root sNN=62.4 and 200 GeV. The away-side dijet induced azimuthal correlation is broadened, non-Gaussian, and peaked away from Delta phi=pi in central and semicentral collisions in all the systems. The broadening and peak location are found to depend upon the number of participants in the collision, but not on the collision energy or beam nuclei. These results are consistent with sound or shock wave models, but pose challenges to Cherenkov gluon radiation models.
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126
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J/psi production versus transverse momentum and rapidity in p+p collisions at square root s=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:232002. [PMID: 17677900 DOI: 10.1103/physrevlett.98.232002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Indexed: 05/16/2023]
Abstract
J/psi production in p+p collisions at square root s=200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over a rapidity range of -2.2<y<2.2 and a transverse momentum range of 0<pT<9 GeV/c. The size of the present data set allows a detailed measurement of both the pT and the rapidity distributions and is sufficient to constrain production models. The total cross section times the branching ratio is Bll sigma pp J/psi=178+/-3stat+/-53sys+/-18norm nb.
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127
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J/psi production versus centrality, transverse momentum, and rapidity in Au+Au collisions at square root sNN=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:232301. [PMID: 17677901 DOI: 10.1103/physrevlett.98.232301] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2006] [Indexed: 05/16/2023]
Abstract
The PHENIX experiment at the BNL Relativistic Heavy Ion Collider (RHIC) has measured J/psi production for rapidities -2.2<y<2.2 in Au+Au collisions at square root sNN=200 GeV. The J/psi invariant yield and nuclear modification factor RAA as a function of centrality, transverse momentum, and rapidity are reported. A suppression of J/psi relative to binary collision scaling of proton-proton reaction yields is observed. Models which describe the lower energy J/psi data at the CERN Super Proton Synchrotron invoking only J/psi destruction based on the local medium density predict a significantly larger suppression at RHIC and more suppression at midrapidity than at forward rapidity. Both trends are contradicted by our data.
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128
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Scaling properties of azimuthal anisotropy in Au+Au and Cu+Cu Collisions at sqrt[s NN]=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:162301. [PMID: 17501413 DOI: 10.1103/physrevlett.98.162301] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2006] [Indexed: 05/15/2023]
Abstract
Differential measurements of elliptic flow (v2) for Au+Au and Cu+Cu collisions at sqrt[sNN]=200 GeV are used to test and validate predictions from perfect fluid hydrodynamics for scaling of v2 with eccentricity, system size, and transverse kinetic energy (KE T). For KE T identical with mT-m up to approximately 1 GeV the scaling is compatible with hydrodynamic expansion of a thermalized fluid. For large values of KE T mesons and baryons scale separately. Quark number scaling reveals a universal scaling of v2 for both mesons and baryons over the full KE T range for Au+Au. For Au+Au and Cu+Cu the scaling is more pronounced in terms of KE T, rather than transverse momentum.
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129
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Evidence for a long-range component in the pion emission source in Au+Au collisions at sqrt sNN=200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:132301. [PMID: 17501193 DOI: 10.1103/physrevlett.98.132301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/26/2006] [Indexed: 05/15/2023]
Abstract
Emission source functions are extracted from correlation functions constructed from charged pions produced at midrapidity in Au+Au collisions at sqrt[s(NN)]=200 GeV. The source parameters extracted from these functions at low k(T) give first indications of a long tail for the pion emission source. The source extension cannot be explained solely by simple kinematic considerations. The possible role of a halo of secondary pions from resonance emissions is explored.
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130
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Atom-by-atom extraction using the scanning tunneling microscope tip-cluster interaction. PHYSICAL REVIEW LETTERS 2007; 98:028304. [PMID: 17358656 DOI: 10.1103/physrevlett.98.028304] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2005] [Revised: 09/11/2006] [Indexed: 05/14/2023]
Abstract
We investigate the atomistic details of a single atom-extraction process realized by using the scanning tunneling microscope tip-cluster interaction on a Ag(111) surface at 6 K. Single atoms are extracted from a silver cluster one atom at a time using small tunneling biases less than 35 mV. Combined total energy calculations and molecular dynamics simulations show a lowering of the atom-extraction barrier upon approaching the tip to the cluster. Thus, a mere tuning of the proximity between the tip and the cluster governs the extraction process. The atomic precision and reproducibility of this procedure are demonstrated by repeatedly extracting single atoms from a silver cluster on an atom-by-atom basis.
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131
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Measurement of direct photon production in p+p collisions at sqrt[s] = 200 GeV. PHYSICAL REVIEW LETTERS 2007; 98:012002. [PMID: 17358469 DOI: 10.1103/physrevlett.98.012002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Indexed: 05/14/2023]
Abstract
Cross sections for midrapidity production of direct photons in p+p collisions at the Relativistic Heavy Ion Collider (RHIC) are reported for transverse momenta of 3 < pT < 16 GeV/c. Next-to-leading order perturbative QCD (pQCD) describes the data well for pT >5 GeV/c, where the uncertainties of the measurement and theory are comparable. We also report on the effect of requiring the photons to be isolated from parton jet energy. The observed fraction of isolated photons is well described by pQCD for pT >7 GeV/c.
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132
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Measurement of high-pT single electrons from heavy-flavor decays in p + p collisions at square root of s = 200 GeV. PHYSICAL REVIEW LETTERS 2006; 97:252002. [PMID: 17280343 DOI: 10.1103/physrevlett.97.252002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/06/2006] [Indexed: 05/13/2023]
Abstract
The momentum distribution of electrons from decays of heavy flavor (charm and bottom) for midrapidity absolute value of y < 0.35 in p + p collisions at square root of s = 200 GeV has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.3 < pT < 9 GeV/c. Two independent methods have been used to determine the heavy-flavor yields, and the results are in good agreement with each other. A fixed-order-plus-next-to-leading-log perturbative QCD calculation agrees with the data within the theoretical and experimental uncertainties, with the data/theory ratio of 1.71+/-0.02stat+/-0.18sys for 0.3 < pT < 9 GeV/c. The total charm production cross section at this energy has also been deduced to be sigma cc = 567+/-57stat+/-193sys microb.
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Abstract
INTRODUCTION As part of the NHS Plan the UK Department of Health has suggested that both patients and general practitioners (GPs) are written to following hospital consultations. We audited the responses of patients and GPs to this practice. PATIENTS AND METHODS A total of 160 patients in one consultant urologist's clinic were included. The consultant had never routinely copied GP letters to patients. The SpR in the same clinic had routinely done so in previous posts. Patients who had received letters (group A) and those who had not (group B) were asked to complete a postal questionnaire. GPs were also sent a questionnaire to assess their opinion. The responses were analysed. RESULTS Questionnaires were sent out to patients (80 to group A and 80 to group B. From this, 100 (62.5%) responses were received (A 48 [60%]; B 52 [65%]). Of respondents, 81% were male. Overall, 98% of those patients who received a letter agreed with its contents, and stated they would keep the letter and take it to a subsequent doctor's appointment. Of respondents, 83% (A) and 96% (B) had never received a doctor's letter before but 83% (40 [83%, A], 43 [83%, B]; P > 0.05) of respondents would like to receive doctors' letters in the future. some 22 GP practices received and completed questionnaires at a PCT meeting and 74% of GPs agreed with the practice of copying patients their letters. CONCLUSIONS The results of this study suggest that patients should be offered a copy of their letter and that their response should be documented in the notes. This may serve to improve communication with the patient but should not be undertaken without their agreement.
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134
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Erratum: Bottom photoproduction measured using decays into muons in dijet events inepcollisions ats=318 GeV[Phys. Rev. D70, 012008 (2004)]. Int J Clin Exp Med 2006. [DOI: 10.1103/physrevd.74.059906] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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135
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Dense-medium modifications to jet-induced hadron pair distributions in Au+Au collisions at sqrt s NN=200 GeV. PHYSICAL REVIEW LETTERS 2006; 97:052301. [PMID: 17026095 DOI: 10.1103/physrevlett.97.052301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Indexed: 05/12/2023]
Abstract
Azimuthal correlations of jet-induced high-p(T) charged hadron pairs are studied at midrapidity in Au+Au collisions at sqrt[s(NN)]=200 GeV. The distribution of jet-associated partner hadrons (1.0<p(T)<2.5 GeV/c) per trigger hadron (2.5<p(T)<4.0 GeV/c) is found to vary with collision centrality, in both shape and yield, indicating a significant effect of the nuclear collision medium on the jet fragmentation process.
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136
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Azimuthal angle correlations for rapidity separated Hadron pairs in d+Au collisions at square root of sNN=200 GeV. PHYSICAL REVIEW LETTERS 2006; 96:222301. [PMID: 16803304 DOI: 10.1103/physrevlett.96.222301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2006] [Indexed: 05/10/2023]
Abstract
Deuteron-gold (d+Au) collisions at the Relativistic Heavy Ion Collider provide ideal platforms for testing QCD theories in dense nuclear matter at high energy. In particular, models suggesting strong saturation effects for partons carrying small nucleon momentum fraction (x) predict modifications to jet production at forward rapidity (deuteron-going direction) in d+Au collisions. We report on two-particle azimuthal angle correlations between charged hadrons at forward/backward (deuteron/gold going direction) rapidity and charged hadrons at midrapidity in d+Au and p+p collisions at square root of sNN=200 GeV. Jet structures observed in the correlations are quantified in terms of the conditional yield and angular width of away-side partners. The kinematic region studied here samples partons in the gold nucleus with x~0.1 to ~0.01. Within this range, we find no x dependence of the jet structure in d+Au collisions.
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137
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Common suppression pattern of eta and pi0 mesons at high transverse momentum in Au + Au collisions at square root S(NN) = 200 GeV. PHYSICAL REVIEW LETTERS 2006; 96:202301. [PMID: 16803168 DOI: 10.1103/physrevlett.96.202301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2006] [Indexed: 05/10/2023]
Abstract
Inclusive transverse momentum spectra of eta mesons have been measured within p(T) = 2-10 GeV/c at midrapidity by the PHENIX experiment in Au + Au collisions at square root S(NN) = 200 GeV. In central Au+Au the eta yields are significantly suppressed compared to peripheral Au + Au, d + Au, and p + p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi0. The ratio of eta to pi0 spectra at high p(T) amounts to 0.40 < R(eta/pi)0 < 0.48 for the three systems, in agreement with the world average measured in hadronic and nuclear reactions and, at large scaled momentum, in e+e- collisions.
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138
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Isolated breast mucormycosis. J Postgrad Med 2006; 52:134-5. [PMID: 16679679] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023] Open
Abstract
Mucormycosis is unusual in surgical practice. Awareness of the classical findings leads to early detection. Excisional therapy whenever possible along with systemic antifungal treatment is the key to successful outcome. A 70 year old female, a known case of diabetes mellitus and chronic obstructive pulmonary disease, on inhalational steroids and oral hypoglycemic agents, presented to us with complaints of sudden onset pain, redness and swelling of left breast. A diagnosis of severe mastitis was made and a release incision was taken. The entire breast became gangrenous in next 24 hours and simple mastectomy had to be performed as a life saving measure. Histopathology revealed mucormycosis of breast. To the best of our knowledge this is the first reported case of mucormycosis of breast in the English literature.
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139
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Single electrons from heavy-flavor decays in collisions at. PHYSICAL REVIEW LETTERS 2006; 96:032001. [PMID: 16486684 DOI: 10.1103/physrevlett.96.032001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/15/2005] [Indexed: 05/06/2023]
Abstract
The invariant differential cross section for inclusive electron production in p+p collisions at [FORMULA: SEE TEXT] has been measured by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider over the transverse momentum range 0.4<or=pT<OR=5.0 GeV/c in the central rapidity region ([FORMULA: SEE TEXT]). The contribution to the inclusive electron spectrum from semileptonic decays of hadrons carrying heavy flavor, i.e., charm quarks or, at high , bottom quarks, is determined via three independent methods. The resulting electron spectrum from heavy-flavor decays is compared to recent leading and next-to-leading order perturbative QCD calculations. The total cross section of charm quark-antiquark pair production is determined to be [FORMULA: SEE TEXT].
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140
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Measurement of identified and inclusive photon second-harmonic parameter and implications for direct photon production in [FORMULA: SEE TEXT] Au+Au. PHYSICAL REVIEW LETTERS 2006; 96:032302. [PMID: 16486688 DOI: 10.1103/physrevlett.96.032302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Indexed: 05/06/2023]
Abstract
The azimuthal distribution of identified pi0 and inclusive photons has been measured in [FORMULA: SEE TEXT] Au+Au collisions with the PHENIX experiment at the Relativistic Heavy-Ion Collider (RHIC). The second-harmonic parameter (nu2) was measured to describe the observed anisotropy of the azimuthal distribution. The measured inclusive photon is consistent with the value expected for the photons from hadron decay and is also consistent with the lack of direct photon signal over the measured pT range 1-6 GeV/c. An attempt is made to extract nu2 of direct photons.
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141
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Nuclear modification of electron spectra and implications for heavy quark energy loss in Au+Au collisions at [FORMULA: SEE TEXT]. PHYSICAL REVIEW LETTERS 2006; 96:032301. [PMID: 16486687 DOI: 10.1103/physrevlett.96.032301] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/17/2005] [Indexed: 05/06/2023]
Abstract
The PHENIX experiment has measured midrapidity ([FORMULA: SEE TEXT]) transverse momentum spectra ([FORMULA: SEE TEXT]) of electrons as a function of centrality in Au+Au collisions at [FORMULA: SEE TEXT]. Contributions from photon conversions and from light hadron decays, mainly Dalitz decays of pi0 and eta mesons, were removed. The resulting nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons carrying heavy quarks. Nuclear modification factors were determined by comparison to nonphotonic electrons in p+p collisions. A significant suppression of electrons at high pT is observed in central Au+Au collisions, indicating substantial energy loss of heavy quarks.
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142
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J/psi production and nuclear effects for d + Au and p + p collisions at square root of S(NN) = 200 GeV. PHYSICAL REVIEW LETTERS 2006; 96:012304. [PMID: 16486446 DOI: 10.1103/physrevlett.96.012304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2005] [Indexed: 05/06/2023]
Abstract
J/psi production in d + Au and p + p collisions at square root of S(NN) = 200 GeV has been measured by the PHENIX experiment at rapidities -2.2 < y < +2.4. The cross sections and nuclear dependence of J/psi production versus rapidity, transverse momentum, and centrality are obtained and compared to lower energy p + A results and to theoretical models. The observed nuclear dependence in d + Au collisions is found to be modest, suggesting that the absorption in the final state is weak and the shadowing of the gluon distributions is small and consistent with Dokshitzer-Gribov-Lipatov-Altarelli-Parisi-based parametrizations that fit deep-inelastic scattering and Drell-Yan data at lower energies.
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143
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Measurement of transverse single-spin asymmetries for midrapidity production of neutral pions and charged hadrons in polarized p + p collisions at square root(s) = 200 GeV. PHYSICAL REVIEW LETTERS 2005; 95:202001. [PMID: 16384048 DOI: 10.1103/physrevlett.95.202001] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/17/2005] [Indexed: 05/05/2023]
Abstract
Transverse single-spin asymmetries to probe the transverse-spin structure of the proton have been measured for neutral pions and nonidentified charged hadrons from polarized proton-proton collisions at midrapidity and square root(s) = 200 GeV. The data cover a transverse momentum (pT) range 1.0-5.0 GeV/c for neutral pions and 0.5-5.0 GeV/c for charged hadrons, at a Feynman-x value of approximately zero. The asymmetries seen in this previously unexplored kinematic region are consistent with zero within errors of a few percent. In addition, the inclusive charged hadron cross section at midrapidity from 0.5 < pT < 7.0 GeV/c is presented and compared to next-to-leading order perturbative QCD (pQCD) calculations. Successful description of the unpolarized cross section above approximately 2 GeV/c suggests that pQCD is applicable in the interpretation of the asymmetry results in the relevant kinematic range.
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144
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Abstract
Microglia, the resident macrophages in the central nervous system (CNS), play a pivotal role in innate and adaptive immune responses in the brain. The immune functions of microglia are regulated by cytokines, including interferon (IFN)-gamma, which is a major mediator of macrophage activation. We describe the transcriptional profile of human fetal microglial cells at 1, 6, and 24 h after IFN-gamma treatment. The results show a change in the expression of 405 genes including transcriptionally induced chemokines, IFN-gamma signaling factors, and major histocompatibility complex genes. Our results demonstrate that activation of microglia by IFN-gamma induces proinflammatory T-lymphocyte-related chemokine genes as well as genes involved in antigen presentation. As a result, signals for T-cell infiltration and antigen presentation are produced to allow for microglia-T-cell interactions that likely contribute to defense against invading pathogens. In sum, our results provide a foundation for the molecular mechanisms of the microglial response to IFN-gamma-a key to understanding cell-mediated immunity of the CNS.
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145
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Saturation of azimuthal anisotropy in Au + Au collisions at (square root)s(NN) = 62-200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:232302. [PMID: 16090463 DOI: 10.1103/physrevlett.94.232302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/19/2004] [Indexed: 05/03/2023]
Abstract
New measurements are presented for charged hadron azimuthal correlations at midrapidity in Au+Au collisions at (square root)s(NN) = 62.4 and 200 GeV. They are compared to earlier measurements obtained at (square root)s(NN) = 130 GeV and in Pb + Pb collisions at (square root)s(NN) = 17.2 GeV. Sizeable anisotropies are observed with centrality and transverse momentum (pT) dependence characteristic of elliptic flow (upsilon2). For a broad range of centralities, the observed magnitudes and trends of the differential anisotropy, upsilon2(pT), change very little over the collision energy range (square root)s(NN) = 62-200 GeV, indicating saturation of the excitation function for upsilon2 at these energies. Such a saturation may be indicative of the dominance of a very soft equation of state for (square root)s(NN) approximately 60-200 GeV.
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146
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Centrality dependence of direct photon production in (square root)S(NN) = 200 GeV Au + Au collisions. PHYSICAL REVIEW LETTERS 2005; 94:232301. [PMID: 16090462 DOI: 10.1103/physrevlett.94.232301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2005] [Indexed: 05/03/2023]
Abstract
The first measurement of direct photons in Au + Au collisions at (square root)S(NN) = 200 GeV is presented. The direct photon signal is extracted as a function of the Au + Au collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. The direct photon yield is shown to scale with the number of nucleon-nucleon collisions for all centralities.
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147
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Deuteron and antideuteron production in Au+Au collisions at square root of s(NN)=200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:122302. [PMID: 15903909 DOI: 10.1103/physrevlett.94.122302] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/01/2004] [Indexed: 05/02/2023]
Abstract
The production of deuterons and antideuterons in the transverse momentum range 1.1<p(T)<4.3 GeV/c at midrapidity in Au+Au collisions at square root of s(NN)=200 GeV has been studied by the PHENIX experiment at RHIC. A coalescence analysis, comparing the deuteron and antideuteron spectra with that of proton and antiproton, has been performed. The coalescence probability is equal for both deuterons and antideuterons and it increases as a function of p(T), which is consistent with an expanding collision zone. Comparing (anti)proton yields, p /p=0.73+/-0.01, with (anti)deuteron yields, d /d=0.47+/-0.03, we estimate that n /n=0.64+/-0.04. The nucleon phase space density is estimated from the coalescence measurement.
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148
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Centrality dependence of charm production from a measurement of single electrons in Au+Au collisions at sqrt[s(NN)]=200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:082301. [PMID: 15783878 DOI: 10.1103/physrevlett.94.082301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/28/2004] [Indexed: 05/24/2023]
Abstract
The PHENIX experiment has measured midrapidity transverse momentum spectra (0.4<p(T)<4.0 GeV/c) of single electrons as a function of centrality in Au+Au collisions at sqrt[s(NN)]=200 GeV. Contributions from photon conversions and Dalitz decays of light neutral mesons are measured by introducing a thin (1.7% X0) converter into the PHENIX acceptance and are statistically removed. The subtracted nonphotonic electron spectra are primarily due to the semileptonic decays of hadrons containing heavy quarks, mainly charm at lower p(T). For all centralities, the charm production cross section is found to scale with the nuclear overlap function, T(AA). For minimum-bias collisions the charm cross section per binary collision is N(cc )/T(AA)=622+/-57(stat)+/-160(syst) microb.
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149
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Nuclear modification factors for hadrons at forward and backward rapidities in deuteron-gold collisions at sqrt[s(NN)]=200 GeV. PHYSICAL REVIEW LETTERS 2005; 94:082302. [PMID: 15783879 DOI: 10.1103/physrevlett.94.082302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2004] [Indexed: 05/24/2023]
Abstract
We report on charged hadron production in deuteron-gold reactions at sqrt[s(NN)]=200 GeV. Our measurements in the deuteron direction cover 1.4<eta<2.2, referred to as forward rapidity, and in the gold direction -2.0<eta<-1.4, referred to as backward rapidity, and a transverse momentum range p(T)=0.5-4.0 GeV/c. We compare the relative yields for different deuteron-gold collision centrality classes. We observe a suppression relative to binary collision scaling at forward rapidity, sensitive to low momentum fraction (x) partons in the gold nucleus, and an enhancement at backward rapidity, sensitive to high momentum fraction partons in the gold nucleus.
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150
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Double helicity asymmetry in inclusive midrapidity pi0 production for polarized p+p collisions at square root s = 200 GeV. PHYSICAL REVIEW LETTERS 2004; 93:202002. [PMID: 15600917 DOI: 10.1103/physrevlett.93.202002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2004] [Indexed: 05/24/2023]
Abstract
We present a measurement of the double longitudinal spin asymmetry in inclusive pi(0) production in polarized proton-proton collisions at sqrt[s]=200 GeV. The data were taken at the Relativistic Heavy Ion Collider with average beam polarizations of 0.27. The measurements are the first in a program to study the longitudinal spin structure of the proton, using strongly interacting probes, at collider energies. The asymmetry is presented for transverse momenta 1-5 GeV/c at midrapidity, where next-to-leading-order perturbative quantum chromodynamic (NLO pQCD) calculations well describe the unpolarized cross section. The observed asymmetry is small and is compared to a NLO pQCD calculation with a range of polarized gluon distributions.
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