677 research outputs found
Heavy Quarkonia Production in p+p Collisions from the PHENIX Experiment
Quarkonia provide a sensitive probe of the properties of the hot dense medium
created in high energy heavy ion collisions. Hard scattering processes result
in the production of heavy quark pairs that interact with the collision medium
during hadronization. These in-medium interactions convey information about the
fundamental properties of the medium itself and can be used to examine the
modification of the QCD confining potential in the collision environment.
Baseline measurements from p+p and d+Au collision systems are used to
distinguish cold nuclear matter effects while measurements from heavy ion
collision systems are used to quantify in-medium effects. The PHENIX experiment
has the capability of detecting heavy quarkonia at via the
decay channel and at via the decay channel.
Recent runs have resulted in the collection of high statistics p+p data sets
that provide an essential baseline reference for heavy ion measurements and
allow for further critical evaluation of heavy quarkonia production mechanisms.
The latest PHENIX results for the production of the in p+p collisions
are presented and future prospects for , and
measurements are discussed.Comment: 4 pages, 2 figures, Proceedings for Quark Matter 200
Bioavailability and kidney responses to Diclofenac in the fathead minnow (Pimephales promelas)
This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.Diclofenac is one of the most widely prescribed nonsteroidal anti-inflammatory drugs worldwide. It is frequently detected in surface waters; however, whether this pharmaceutical poses a risk to aquatic organisms is debated. Here we quantified the uptake of diclofenac by the fathead minnow (Pimephales promelas) following aqueous exposure (0.2-25.0 μg L(-1)) for 21 days, and evaluated the tissue and biomolecular responses in the kidney. Diclofenac accumulated in a concentration- and time-dependent manner in the plasma of exposed fish. The highest plasma concentration observed (for fish exposed to 25 μg L(-1) diclofenac) was within the therapeutic range for humans. There was a strong positive correlation between exposure concentration and the number of developing nephrons observed in the posterior kidney. Diclofenac was not found to modulate the expression of genes in the kidney associated with its primary mode of action in mammals (prostaglandin-endoperoxide synthases) but modulated genes associated with kidney repair and regeneration. There were no significant adverse effects following 21 days exposure to concentrations typical of surface waters. The combination of diclofenac's uptake potential, effects on kidney nephrons and relatively small safety margin for some surface waters may warrant a longer term chronic health effects analysis for diclofenac in fish.This work was funded by Knowledge Transfer Partnership (KTP): Use of ‘omic’ technologies in the environmental risk assessment of pharmaceuticals (KTP007650) and AstraZeneca’s Safety, Health and Environment (SHE) Research Programme. We thank Lina Gunnarsson, Matt Winter and James Cresswell (Exeter University), and former members of the Brixham Environmental Laboratory for their advice and assistance. Authors declare no competing financial interest
Experience with Community‐Based Amphotericin B Infusion Therapy
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90368/1/phco.25.5.690.63591.pd
Transverse Spin at PHENIX: Results and Prospects
The Relativistic Heavy Ion Collider (RHIC), as the world's first and only
polarized proton collider, offers a unique environment in which to study the
spin structure of the proton. In order to study the proton's transverse spin
structure, the PHENIX experiment at RHIC took data with transversely polarized
beams in 2001-02 and 2005, and it has plans for further running with transverse
polarization in 2006 and beyond. Results from early running as well as
prospective measurements for the future will be discussed.Comment: 6 pages, 2 figures, presented at Transversity 2005, Como, Ital
Collision geometry scaling of Au+Au pseudorapidity density from sqrt(s_NN) = 19.6 to 200 GeV
The centrality dependence of the midrapidity charged particle multiplicity in
Au+Au collisions at sqrt(s_NN) = 19.6 and 200 GeV is presented. Within a simple
model, the fraction of hard (scaling with number of binary collisions) to soft
(scaling with number of participant pairs) interactions is consistent with a
value of x = 0.13 +/- 0.01(stat) +/- 0.05(syst) at both energies. The
experimental results at both energies, scaled by inelastic p(pbar)+p collision
data, agree within systematic errors. The ratio of the data was found not to
depend on centrality over the studied range and yields a simple linear scale
factor of R_(200/19.6) = 2.03 +/- 0.02(stat) +/- 0.05(syst).Comment: 5 pages, 4 figures, submitted to PRC-R
Centrality dependence of charged antiparticle to particle ratios near mid-rapidity in d+Au collisions at sqrt(s_NN)=200 GeV
The ratios of the yields of charged antiparticles to particles have been
obtained for pions, kaons, and protons near mid-rapidity for d+Au collisions at
sqrt(s_NN) = 200 GeV as a function of centrality. The reported values represent
the ratio of the yields averaged over the rapidity range of 0.1<y_pi<1.3 and
0<y_(K,p)<0.8, where positive rapidity is in the deuteron direction, and for
transverse momenta 0.1<p_(T)^(pi,K)<1.0 GeV/c and 0.3<p_(T)^(p)<1.0 GeV/c.
Within the uncertainties, a lack of centrality dependence is observed in all
three ratios. The data are compared to results from other systems and model
calculations.Comment: 6 pages, 4 figures, submitted to PR
Charged-Particle Pseudorapidity Distributions in Au+Au Collisions at sqrt(s_NN)=62.4 GeV
The charged-particle pseudorapidity density for Au+Au collisions at
sqrt(s_NN)=62.4 GeV has been measured over a wide range of impact parameters
and compared to results obtained at other energies. As a function of collision
energy, the pseudorapidity distribution grows systematically both in height and
width. The mid-rapidity density is found to grow approximately logarithmically
between AGS energies and the top RHIC energy. As a function of centrality,
there is an approximate factorization of the centrality dependence of the
mid-rapidity yields and the overall multiplicity scale. The new results at
sqrt(s_NN)=62.4 GeV confirm the previously observed phenomenon of ``extended
longitudinal scaling'' in the pseudorapidity distributions when viewed in the
rest frame of one of the colliding nuclei. It is also found that the evolution
of the shape of the distribution with centrality is energy independent, when
viewed in this reference frame. As a function of centrality, the total charged
particle multiplicity scales linearly with the number of participant pairs as
it was observed at other energies.Comment: 6 pages, 7 figures, submitted to Phys. Rev. C - Rapid Communication
Event-by-event fluctuations of azimuthal particle anisotropy in Au+Au collisions at sqrt(s_NN) = 200 GeV
This paper presents the first measurement of event-by-event fluctuations of
the elliptic flow parameter v_2 in Au+Au collisions at sqrt(s_NN) = 200GeV as a
function of collision centrality. The relative non-statistical fluctuations of
the v_2 parameter are found to be approximately 40%. The results, including
contributions from event-by-event elliptic flow fluctuations and from azimuthal
correlations that are unrelated to the reaction plane (non-flow correlations),
establish an upper limit on the magnitude of underlying elliptic flow
fluctuations. This limit is consistent with predictions based on spatial
fluctuations of the participating nucleons in the initial nuclear overlap
region. These results provide important constraints on models of the initial
state and hydrodynamic evolution of relativistic heavy ion collisions.Comment: 5 pages, 2 figures, Published in Phys. Rev. Lett
Centrality and pseudorapidity dependence of elliptic flow for charged hadrons in Au+Au collisions at sqrt(sNN) = 200 GeV
This paper describes the measurement of elliptic flow for charged particles
in Au+Au collisions at sqrt(sNN)=200 GeV using the PHOBOS detector at the
Relativistic Heavy Ion Collider (RHIC). The measured azimuthal anisotropy is
presented over a wide range of pseudorapidity for three broad collision
centrality classes for the first time at this energy. Two distinct methods of
extracting the flow signal were used in order to reduce systematic
uncertainties. The elliptic flow falls sharply with increasing eta at 200 GeV
for all the centralities studied, as observed for minimum-bias collisions at
sqrt(sNN)=130 GeV.Comment: Final published version: the most substantive change to the paper is
the inclusion of a complete description of how the errors from the hit-based
and track-based analyses are merged to produce the 90% C.L. errors quoted for
the combined results shown in Fig.
Non-flow correlations and elliptic flow fluctuations in gold-gold collisions at sqrt(s_NN)= 200 GeV
This paper presents results on event-by-event elliptic flow fluctuations in
Au+Au collisions at sqrt(s_NN)=200Gev, where the contribution from non-flow
correlations has been subtracted. An analysis method is introduced to measure
non-flow correlations, relying on the assumption that non-flow correlations are
most prominent at short ranges (Delta eta < 2). Assuming that non-flow
correlations are of the order that is observed in p+p collisions for long range
correlations (Delta eta > 2), relative elliptic flow fluctuations of
approximately 30-40% are observed. These results are consistent with
predictions based on spatial fluctuations of the participating nucleons in the
initial nuclear overlap region. It is found that the long range non-flow
correlations in Au+Au collisions would have to be more than an order of
magnitude stronger compared to the p+p data to lead to the observed azimuthal
anisotropy fluctuations with no intrinsic elliptic flow fluctuations.Comment: 9 pages, 7 figures, Published in Phys. Rev.
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