482 research outputs found
A Compact Beam Stop for a Rare Kaon Decay Experiment
We describe the development and testing of a novel beam stop for use in a
rare kaon decay experiment at the Brookhaven AGS. The beam stop is located
inside a dipole spectrometer magnet in close proximity to straw drift chambers
and intercepts a high-intensity neutral hadron beam. The design process,
involving both Monte Carlo simulations and beam tests of alternative beam-stop
shielding arrangements, had the goal of minimizing the leakage of particles
from the beam stop and the resulting hit rates in detectors, while preserving
maximum acceptance for events of interest. The beam tests consisted of
measurements of rates in drift chambers, scintilation counter hodoscopes, a gas
threshold Cherenkov counter, and a lead glass array. Measurements were also
made with a set of specialized detectors which were sensitive to low-energy
neutrons, photons, and charged particles. Comparisons are made between these
measurements and a detailed Monte Carlo simulation.Comment: 39 pages, 14 figures, submitted to Nuclear Instruments and Method
Drug–drug Interaction between Pravastatin and Gemfibrozil (Antihyperlipidemic) with Gliclazide (Antidiabetic) in Rats
Diabetes mellitus is a condition of increased blood glucose level in the body. Antihyperlipidemic drugs like statins and fibrates are widely used for prophylactic treatment in dyslipideamia and atherosclerosis. Diabetic dislipidemia exists with increased triglycerides, low HDL and high LDL levels. Hence, with oral hypoglycemic drugs, the addition of a lipid-lowering drug is necessary for controlling dislipidemia. In such a situation, there may be chances of drug–drug interactions between antidiabetic and antihyperlipidemic drugs. The present study is planned to evaluate the safety of gliclazide (antidiabetic) in the presence of pravastatin and gemfibrozil (antihyperlpidemic) in rats. Studies in normal and alloxan-induced diabetic rats were conducted with oral doses of gliclazide and their combination with pravastatin and gemfibrozil, with an adequate washout period in between the treatments. Blood samples were collected in rats by retroorbital puncture at 0, 1, 2, 3, 4, 6, 8, 10 and 12 h. All the blood samples were analyzed for glucose by GOD –POD. Gliclazide (½ TD) produced hypoglycemic activity in normal and diabetic rats, with peak activity at 2 and 8 h. Pravastatin (TD) + gemfibrozil (TD) combination treatment increased the hypoglycemic effect of gliclazide in normal rats or diabetic rats when administered together. The interaction observed due to inhibition of both the enzymes (CYP 450 2C9 and CYP 450 3A4) responsible for the metabolism of gliclazide showed increased half-life, which was seen in the present study. Because concomitant administration of gliclazide with provastatin and gemfibrozil in diabetes is associated with atherosclerosis, it should be contraindicated or used with caution
Measurement of E2 transition strengths in Mg32,34
The degree of collectivity in the neutron-rich nuclei Mg32 and Mg34 has been determined via intermediate-energy Coulomb excitation in inverse kinematics. Measured energies of the first excited 2+ states and reduced electric quadrupole transition probabilities B(E2;0g.s.+→21+) are presented for Mg32 and Mg34. The results agree with previous measurements and confirm the placement of both nuclei within the "island of inversion.
Measurement of the Decay Asymmetry Parameters in and
We have measured the weak decay asymmetry parameters (\aLC ) for two \LC\
decay modes. Our measurements are \aLC = -0.94^{+0.21+0.12}_{-0.06-0.06} for
the decay mode and \aLC = -0.45\pm 0.31 \pm
0.06 for the decay mode . By combining these
measurements with the previously measured decay rates, we have extracted the
parity-violating and parity-conserving amplitudes. These amplitudes are used to
test models of nonleptonic charmed baryon decay.Comment: 11 pages including the figures. Uses REVTEX and psfig macros. Figures
as uuencoded postscript. Also available as
http://w4.lns.cornell.edu/public/CLNS/1995/CLNS95-1319.p
Production and Decay of D_1(2420)^0 and D_2^*(2460)^0
We have investigated and final states and
observed the two established charmed mesons, the with mass
MeV/c and width MeV/c and
the with mass MeV/c and width
MeV/c. Properties of these final states, including
their decay angular distributions and spin-parity assignments, have been
studied. We identify these two mesons as the doublet predicted
by HQET. We also obtain constraints on {\footnotesize } as a function of the cosine of the relative phase of the two
amplitudes in the decay.Comment: 15 pages in REVTEX format. hardcopies with figures can be obtained by
sending mail to: [email protected]
Measurement of the branching fraction for
We have studied the leptonic decay of the resonance into tau
pairs using the CLEO II detector. A clean sample of tau pair events is
identified via events containing two charged particles where exactly one of the
particles is an identified electron. We find . The result is consistent with
expectations from lepton universality.Comment: 9 pages, RevTeX, two Postscript figures available upon request, CLNS
94/1297, CLEO 94-20 (submitted to Physics Letters B
Observation of the Charmed Baryon Decays to , , and
We have observed two new decay modes of the charmed baryon into
and using data collected with the
CLEO II detector. We also present the first measurement of the branching
fraction for the previously observed decay mode . The branching fractions for these three modes relative to
are measured to be , , and , respectively.Comment: 12 page uuencoded postscript file, postscript file also available
through http://w4.lns.cornell.edu/public/CLN
Single Spin Asymmetry in Polarized Proton-Proton Elastic Scattering at GeV
We report a high precision measurement of the transverse single spin
asymmetry at the center of mass energy GeV in elastic
proton-proton scattering by the STAR experiment at RHIC. The was measured
in the four-momentum transfer squared range \GeVcSq, the region of a significant interference between the
electromagnetic and hadronic scattering amplitudes. The measured values of
and its -dependence are consistent with a vanishing hadronic spin-flip
amplitude, thus providing strong constraints on the ratio of the single
spin-flip to the non-flip amplitudes. Since the hadronic amplitude is dominated
by the Pomeron amplitude at this , we conclude that this measurement
addresses the question about the presence of a hadronic spin flip due to the
Pomeron exchange in polarized proton-proton elastic scattering.Comment: 12 pages, 6 figure
The selection of comparators for randomized controlled trials of health-related behavioral interventions: recommendations of an NIH expert panel
Objectives: To provide recommendations for the selection of comparators for randomized controlled trials of health-related behavioral interventions. Study Design and Setting: The National Institutes of Health Office of Behavioral and Social Science Research convened an expert panel to critically review the literature on control or comparison groups for behavioral trials and to develop strategies for improving comparator choices and for resolving controversies and disagreements about comparators. Results: The panel developed a Pragmatic Model for Comparator Selection in Health-Related Behavioral Trials. The model indicates that the optimal comparator is the one that best serves the primary purpose of the trial but that the optimal comparator's limitations and barriers to its use must also be taken into account. Conclusion: We developed best practice recommendations for the selection of comparators for health-related behavioral trials. Use of the Pragmatic Model for Comparator Selection in Health-Related Behavioral Trials can improve the comparator selection process and help resolve disagreements about comparator choices
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