2,321 research outputs found
The thermal model on the verge of the ultimate test: particle production in Pb-Pb collisions at the LHC
We investigate the production of hadrons in nuclear collisions within the
framework of the thermal (or statistical hadronization) model. We discuss both
the ligh-quark hadrons as well as charmonium and provide predictions for the
LHC energy. Even as its exact magnitude is dependent on the charm production
cross section, not yet measured in Pb-Pb collisions, we can confidently predict
that at the LHC the nuclear modification factor of charmonium as a function of
centrality is larger than that observed at RHIC and compare the experimental
results to these predictions.Comment: 4 pages, 3 figures; proceedings of QM201
A Phase II Study of Irinotecan and Carboplatin in Advanced Non-small Cell Lung Cancer with Pharmacogenomic Analysis: Final Report
PurposeWe conducted a phase II study of carboplatin and irinotecan in patients with advanced non-small cell lung cancer (NSCLC). In addition, we studied the correlation between certain genotypes of enzymes involved in irinotecan metabolism with efficacy and toxicity.Patients and MethodsPatients with stage IIIB, IV, or recurrent NSCLC received a combination of irinotecan and carboplatin every 3 weeks at a dose of 200 mg/m2 and area under the curve of 5. Pharmacogenomic analysis was performed on several genes of interest (ABCB1, CYP3A4*1B, ERCC2, GSTP1, UGT1A1*28, and XRCC1).ResultsForty-two patients enrolled between December 2001 and January 2004. Six patients achieved partial responses (14%), and 19 (45%) had stable disease. The median progression-free survival was 6.9 months. The median overall survival was 11.7 months, with 1-year overall survival of 42%. The most common toxicities were hematologic; grade 3 or 4 neutropenia was experienced by 26 patients (62%) during treatment, and 15 patients (36%) experienced grade 3 or 4 thrombocytopenia. The homozygous UGT1A1*28 (7/7) genotype was associated with grade 4 neutropenia in three of four patients (75%), but only eight out of 30 (27%) with 6/6 or 6/7 genotypes experienced grade 4 neutropenia (p = 0.09). None of the 14 patients with the GSTP1 I105V A/A genotype had a partial response, as opposed to five out of 19 (26%) of those with the G/A or G/G genotypes (p = 0.057).ConclusionThe combination of carboplatin and irinotecan is an active combination in NSCLC, with response rates comparable with other platinum-containing doublets. Further studies with irinotecan should incorporate prospective pharmacogenomic analysis to identify markers for response and toxicity
Scalable Rules for Coherent Group Motion in a Gregarious Vertebrate
Individuals of gregarious species that initiate collective movement require mechanisms of cohesion in order to maintain advantages of group living. One fundamental question in the study of collective movement is what individual rules are employed when making movement decisions. Previous studies have revealed that group movements often depend on social interactions among individual members and specifically that collective decisions to move often follow a quorum-like response. However, these studies either did not quantify the response function at the individual scale (but rather tested hypotheses based on group-level behaviours), or they used a single group size and did not demonstrate which social stimuli influence the individual decision-making process. One challenge in the study of collective movement has been to discriminate between a common response to an external stimulus and the synchronization of behaviours resulting from social interactions. Here we discriminate between these two mechanisms by triggering the departure of one trained Merino sheep (Ovis aries) from groups containing one, three, five and seven naĂŻve individuals. Each individual was thus exposed to various combinations of already-departed and non-departed individuals, depending on its rank of departure. To investigate which individual mechanisms are involved in maintaining group cohesion under conditions of leadership, we quantified the temporal dynamic of response at the individual scale. We found that individuals' decisions to move do not follow a quorum response but rather follow a rule based on a double mimetic effect: attraction to already-departed individuals and attraction to non-departed individuals. This rule is shown to be in agreement with an adaptive strategy that is inherently scalable as a function of group size
Study of dimuon production in Indium-Indium collisions with the NA60 experiment
The NA60 experiment at the CERN-SPS is devoted to the study of dimuon
production in heavy-ion and proton-nucleus collisions. We present preliminary
results from the analysis of Indium-Indium collisions at 158 GeV per nucleon.
The topics covered are low mass vector meson production, J/psi production and
suppression, and the feasibility of the open charm measurement from the dimuon
continuum in the mass range below the J/psi peak.Comment: Contribution at XXXXth Rencontres de Moriond, "QCD and High Energy
Hadronic Interactions
Meson Production in In-In Collisions and the Puzzle
The NA60 experiment measured dimuon production in In-In collisions at 158
AGeV. This paper presents a high statistics measurement of with
the specific objective to provide insight on the puzzle, i.e. the
difference in the inverse slopes and absolute yields measured by NA49 and
NA50 in the kaon and lepton channel, respectively. Transverse momentum
distributions were studied as a function of centrality. The slope parameter
shows a rapid increase with centrality, followed by a saturation. Variations of
with the fit range of the order of 15 MeV were observed, possibly as a
consequence of radial flow. The meson yield normalized to the number of
participants increases with centrality and is consistently higher than the
yield measured by the NA49 experiment at any centrality.Comment: 4 Pages, 2 Figures. Proceedings of the 20 International
Conference on Ultra-Relativistic Nucleus Nucleus Collision
Latest results from NA60
The NA60 experiment has measured the production of muon pairs and of charged
particles in In+In collisions at a beam energy of 158 AGeV. For invariant
dimuon masses below the phi the space-time averaged rho spectral function was
isolated by a novel procedure. It shows a strong broadening but essentially no
shift in mass. The production of J/psi was measured as a function of the
collision centrality. As in previous experiments studying Pb+Pb collisions an
anomalous supression is observed, setting in at approximately 90 participant
nucleons. Using the charged particles the reaction plane was reconstructed. The
elliptic flow of charged particles increases with pt showing a saturation for
pt > 2GeV/c. For the first time azimuthal distributions for J/psi are shown.Comment: 9 pages, 11 figures, talk given at the conference "Strangeness in
Quark Matter 2006 (SQM2006)", March 2006, Los Angeles, USA, accepted for
publication in Journal of Physics
Evidence for radial flow of thermal dileptons in high-energy nuclear collisions
The NA60 experiment at the CERN SPS has studied low-mass dimuon production in
158 AGeV In-In collisions. An excess of pairs above the known meson decays has
been reported before. We now present precision results on the associated
transverse momentum spectra. The slope parameter Teff extracted from the
spectra rises with dimuon mass up to the rho, followed by a sudden decline
above. While the initial rise is consistent with the expectations for radial
flow of a hadronic decay source, the decline signals a transition to an
emission source with much smaller flow. This may well represent the first
direct evidence for thermal radiation of partonic origin in nuclear collisions.Comment: Accepted for publication in Physical Review Letter
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