1,476 research outputs found
Dilepton Production at Fermilab and RHIC
Some recent results from several fixed-target dimuon production experiments
at Fermilab are presented. In particular, we discuss the use of Drell-Yan data
to determine the flavor structure of the nucleon sea, as well as to deduce the
energy-loss of partons traversing nuclear medium. Future dilepton experiments
at RHIC could shed more light on the flavor asymmetry and possible
charge-symmetry-violation of the nucleon sea. Clear evidence for scaling
violation in the Drell-Yan process could also be revealed at RHIC.Comment: 5 pages, talk presented at the RIKEN-BNL Workshop on 'Hard Parton
Physics in Nucleus-Nucleus collisions, March 199
Hunting for CDF Multi-Muon "Ghost" Events at Collider and Fixed-Target Experiments
In 2008 the CDF collaboration discovered a large excess of events containing
two or more muons, at least one of which seemed to have been produced outside
the beam pipe. We investigate whether similar "ghost" events could (and should)
have been seen in already completed experiments. The CDF di-muon data can be
reproduced by a simple model where a relatively light X particle undergoes
four-body decay. This model predicts a large number of ghost events in Fermilab
fixed-target experiments E772, E789 and E866, applying the cuts optimized for
analyses of Drell-Yan events. A correct description of events with more than
two muons requires a more complicated model, where two X particles are produced
from a very broad resonance Y. This model can be tested in fixed-target
experiments only if the cut on the angles, or rapidities, of the muons can be
relaxed. Either way, the UA1 experiment at the CERN ppbar collider should have
observed O(100) ghost events.Comment: 15 pages, 9 figure
Suppression of Quarkonium Production in Heavy Ion Collisions at RHIC and LHC
A model for the production of quarkonium states in the midrapidity region at
RHIC and LHC energy range is presented which explores well understood
properties of QCD only. An increase of the quarkonium hadronisation time with
the initial energy leads to a gradual change of the most important phenomena
from fixed target- to collider-energies. We evaluate nuclear effects in the
quarkonium production due to medium modification of the momentum distribution
of the heavy quarks produced in the hard interactions, i.e. due to the
broadening of the transverse momentum distribution. Other nuclear effects, i.e.
nuclear shadowing and parton energy loss, are also evaluated.Comment: 5 pages, 1 table, 1 figure, Contribution to the Proceedings of the V
International Conference on Strangeness in Quark Matter July 20-25, 2000
Berkeley, Californi
Prescribing Practices and Polypharmacy in Kitovu Hospital, Uganda
This audit of prescribing practices explores recent trends at Kitovu Hospital, Uganda. The average number of drugs prescribed per patient was 2.89 ± 0.11, of which 1.79±0.09 were generics and 0.69±0.06 antibiotics. No injections were prescribed. Patient essential drug knowledge was 100% while the adequacy of labelling was 0%. The number of drugs prescribed correlated positively with patient age, was greater for female patients, similar for doctors and clinical officers but greater in medical (3.30±0.15, n=50) than surgical (2.48±0.13, n=50) outpatient clinics. The mean consultation time was 6.56 min and 10.25 min per patient in medical and surgical outpatient clinics respectively. The patient essential knowledge indicators were greatly improved but only modest reduction in polypharmacy was evident compared to the Ugandan Pharmaceutical Sector national survey of 2002. Antibiotic prescription was high and generic prescribing was found to be low. Policy changes are required to enhance rational drug use in the health sector in Uganda.Keywords: Polypharmacy, generics, antibiotics, regional referral hospital, outpatient clinicEast and Central African Journal of Pharmaceutical Sciences Vol. 13 (2010) 66-7
Low mass lepton pair production in hadron collisions
The hadroproduction of lepton pairs with mass and transverse momentum
can be described in perturbative QCD by the same partonic subprocesses as
prompt photon production. We demonstrate that, like prompt photon production,
lepton pair production is dominated by quark-gluon scattering in the region
. This leads to sensitivity to the gluon density in kinematical
regimes that are accessible both at collider and fixed target experiments while
eliminating the theoretical and experimental uncertainties present in prompt
photon production.Comment: Talk given by M. Klasen at the International Conference on the
Structure and Interactions of the Photon, PHOTON 99, Freiburg i. Brsg.,
Germany, May 23-27, 1999. To be published in the proceedings. 6 pages, 6
postscript figure
Jet Tomography of Hot and Cold Nuclear Matter
Medium modification of parton fragmentation functions induced by multiple
scattering and gluon bremsstrahlung is shown to describe the recent HERMES data
in deeply inelastic scattering (DIS) very well, providing the first evidence of
-dependence of the modification. The energy loss is found to be
GeV/fm for a 10-GeV quark in a nucleus. Including
the effect of expansion, analysis of the spectra in central
collisions at GeV yields an averaged energy loss equivalent to
GeV/fm in a static medium. Predictions for central
collisions at GeV are also given.Comment: 4 pages in RevTex with 3 ps figures, final version published in Phys.
Rev. Letter
Using non-participant observation to uncover mechanisms: insights from a realist evaluation
This article outlines how a realist evaluation of dementia care in hospitals used non-participant observation to support the refinement and testing of mechanisms likely to lead to the use of person-centred care. We found that comments and explanations of their actions from hospital staff during observation periods provided insights into the reasoning that generated their actions for care in real time. This informed subsequent data collection and analysis. Two worked examples of mechanisms first identified during non-participant observation demonstrate (1) how they were uncovered, and (2) how this informed research activities for theory refinement. Early, iterative engagement with the analytic process, primarily involving reflection and debate with the research team, maximised the potential of observation data to support surfacing underlying mechanisms, linking them to specific contexts and outcomes.Peer reviewedFinal Accepted Versio
Phonon Band Structure and Thermal Transport Correlation in a Layered Diatomic Crystal
To elucidate the relationship between a crystal's structure, its thermal
conductivity, and its phonon dispersion characteristics, an analysis is
conducted on layered diatomic Lennard-Jones crystals with various mass ratios.
Lattice dynamics theory and molecular dynamics simulations are used to predict
the phonon dispersion curves and the thermal conductivity. The layered
structure generates directionally dependent thermal conductivities lower than
those predicted by density trends alone. The dispersion characteristics are
quantified using a set of novel band diagram metrics, which are used to assess
the contributions of acoustic phonons and optical phonons to the thermal
conductivity. The thermal conductivity increases as the extent of the acoustic
modes increases, and decreases as the extent of the stop bands increases. The
sensitivity of the thermal conductivity to the band diagram metrics is highest
at low temperatures, where there is less anharmonic scattering, indicating that
dispersion plays a more prominent role in thermal transport in that regime. We
propose that the dispersion metrics (i) provide an indirect measure of the
relative contributions of dispersion and anharmonic scattering to the thermal
transport, and (ii) uncouple the standard thermal conductivity
structure-property relation to that of structure-dispersion and
dispersion-property relations, providing opportunities for better understanding
of the underlying physical mechanisms and a potential tool for material design.Comment: 30 pages, 10 figure
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