3,282 research outputs found
Testing the Flyby Anomaly with the GNSS Constellation
We propose the concept of a space mission to probe the so called flyby
anomaly, an unexpected velocity change experienced by some deep-space probes
using earth gravity assists. The key feature of this proposal is the use of
GNSS systems to obtain an increased accuracy in the tracking of the approaching
spacecraft, mainly near the perigee. Two low-cost options are also discussed to
further test this anomaly: an add-on to an existing spacecraft and a dedicated
mission.Comment: 8 pages, 1 figure, 4 table
Simple analytic solution of fireball hydrodynamics
A new family of simple analytic solutions of hydrodynamics is found for
non-relativistic, rotationally symmetric fireballs assuming an ideal gas
equation of state. The solution features linear flow profile and a non-trivial
transverse temperature profile. The radial temperature gradient vanishes only
in the collisionless gas limit. The Zimanyi-Bondorf-Garpman solution and the
Buda-Lund parameterization of expanding hydrodynamical sources are recovered as
special cases. The results are applied to predict new features of proton-proton
correlations and spectra data at 1.93 AGeV Ni + Ni reactions.Comment: Latex, Revte
Studies of multiplicity in relativistic heavy-ion collisions
In this talk I'll review the present status of charged particle multiplicity
measurements from heavy-ion collisions. The characteristic features of
multiplicity distributions obtained in Au+Au collisions will be discussed in
terms of collision centrality and energy and compared to those of p+p
collisions. Multiplicity measurements of d+Au collisions at 200 GeV
nucleon-nucleon center-of-mass energy will also be discussed. The results will
be compared to various theoretical models and simple scaling properties of the
data will be identified.Comment: "Focus on Multiplicity" Internationsl Workshop on Particle
Multiplicity in Relativistic Heavy Ion Collisions, Bari, Italy, June 17-19,
2003, 16 pages, 15 figure
On the Equation of State of Nuclear Matter in 158A GeV Pb+Pb Collisions
Within a hydrodynamical approach we investigate the sensitivity of single
inclusive momentum spectra of hadrons in 158A GeV Pb+Pb collisions to three
different equations of state of nuclear matter. Two of the equations of state
are based on lattice QCD results and include a phase transition to a
quark-gluon plasma. The third equation of state has been extracted from the
microscopic transport code RQMD under the assumption of complete local
thermalization. All three equations of state provide reasonable fits to data
taken by the NA44 and NA49 Collaborations. The initial conditions before the
evolution of the fireballs and the space-time evolution pictures differ
dramatically for the three equations of state when the same freeze-out
temperature is used in all calculations. However, the softest of the equations
of state results in transverse mass spectra that are too steep in the central
rapidity region. We conclude that the transverse particle momenta are
determined by the effective softness of the equation of state during the
fireball expansion.Comment: 4 pages, including 4 figures and 2 tables. For a PostScript file of
the manuscript, you can also goto http://t2.lanl.gov/schlei/eprint.htm
Baryon phase-space density in heavy-ion collisions
The baryon phase-space density at mid-rapidity from central heavy-ion
collisions is estimated from proton spectra with interferometry and deuteron
coalescence measurements. It is found that the mid-rapidity phase-space density
of baryons is significantly lower at the SPS than the AGS, while those of total
particles (pion + baryon) are comparable. Thermal and chemical equilibrium
model calculations tend to over-estimate the phase-space densities at both
energies.Comment: 5 pages, 2 tables, no figure. RevTeX style. Accepted for publication
in Phys. Rev. C Rapid Communicatio
Two-kaon correlations in central Pb + Pb collisions at 158 A GeV/c
Two-particle interferometry of positive kaons is studied in Pb + Pb
collisions at mean transverse momenta and 0.91 GeV/c. A
three-dimensional analysis was applied to the lower data, while a
two-dimensional analysis was used for the higher data. We find that the
source size parameters are consistent with the scaling curve observed in
pion correlation measurements in the same collisions, and that the duration
time of kaon emission is consistent with zero within the experimental
sensitivity.Comment: 4 pages incl. 1 table and 3 fig's; RevTeX; accepted for publication
in PR
Systematic Study of the Kaon to Pion Multiplicity Ratios in Heavy-Ion Collisions
We present a systematic study of the kaon to pion multiplicity ratios (K+/pi+
and K-/pi-) in heavy-ion collisions from AGS to RHIC energy using the
Relativistic Quantum Molecular Dynamics (RQMD) model. The model satisfactorily
describes the available experimental data on K+/pi+ and K-/pi-. Within the
model, we find that the strong increase of the ratios with the number of
participants is mainly due to hadronic rescattering of produced mesons with
ingoing baryons and their resonances. The enhancement of K/pi in heavy-ion
collisions with respect to elementary p+p interactions is larger at AGS energy
than SPS energy, and decreases smoothly with bombarding energy. The total
multiplicity ratios at RHIC energy are predicted by RQMD to be K+/pi+ = 0.19
and K-/pi- = 0.15.Comment: 10 pages, 8 figures, RevTeX style. A section is added to discuss
effects of rope formatio
Baryon Junction Loops in HIJING/B\=Bv2.0 and the Baryon/Meson Anomaly at RHIC
A new version, v2.0, of the HIJING/B\=B Monte Carlo nuclear collision event
generator is introduced in order to explore further the possible role of baryon
junctions loops in the baryon/meson anomaly (2 5 GeV/c) observed in
200A GeV Au+Au reactions at RHIC. We show that junction loops with an enhanced
intrinsic GeV/c transverse momentum kick may provide a partial
explanation of the anomaly as well as other important baryon stopping
observables.Comment: 27 pages, Latex(revtex), 8 figure
Gemcitabine and Irinotecan for Patients with Untreated Extensive Stage Small Cell Lung Cancer: SWOG 0119
IntroductionTo evaluate the activity of a nonplatinum-, nonetoposide-containing regimen for patients with extensive stage small cell lung cancer.MethodsPatients with untreated extensive stage small cell lung cancer were treated with gemcitabine 1000 mg/m2 and irinotecan 100 mg/m2 on days 1 and 8 of a 21-day cycle for a maximum of six cycles. Patients with brain metastases were eligible if asymptomatic or controlled after radiation.ResultsEighty-four eligible patients with untreated extensive stage small cell lung cancer with adequate organ function and a performance status of 0â2 were accrued. The median age was 64 years (range, 42â85) and 45 (54%) were women. Six cycles were completed by 28 (33%) patients. Some degree of diarrhea occurred in 57% (grade 3/4, 18%). Other grade 3/4 toxicities were neutropenia (26%), anemia (10%), thrombocytopenia (8%), febrile neutropenia (5%), fatigue (11%), nausea (10%), and vomiting (8%). The response rate was 32% (95% confidence interval: 22%â43%) among the 81 patients with measurable disease. The median survival was 8.5 months (95% confidence interval: 7.0â9.8) with 1- and 2-year survival rates of 26% and 7%, respectively. Salvage therapy data were captured by prospective collection, and only 50% of patients were treated secondarily.ConclusionThe overall response rate with the combination of gemcitabine and irinotecan was disappointing, and the median survival rate was lower than expected. Further development of this combination in small cell lung cancer is not recommended
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