11,650 research outputs found
Signal conditioning circuit apparatus
A signal conditioning circuit is described including operational amplifier, a variable source of offset potential, and four resistive impedance. The circuit has constant input impedance independent of gain and offset adjustments. Gain change is effected by varying one of the impedances in an amplifier feedback circuit; offset adjustment is effected through variation of the offset potential source
Tunneling through Color Glass Condensate and True Black Disks
We discover new vacuum solutions of the JIMWLK equation, which correspond to
center of a gauge group. We improve the color glass condensate (CGC) model by
an explicit usage of a density matrix. Studying scattering of CGC states in an
external color field, we observe that an amplitude is naturally expressed via
group characters. We construct an example that shows how new thin effects may
be potentially observed in peripheral collisions. We prove that at any parton
density a gluonic CGC state does not become a true black disk. We find a wave
function of a true black disk and show that it necessarily contains many
quarks. This result corresponds to the necessity of nonvacuum Reggeon loops in
a formation of a true black disk.Comment: 13 pages, 2 figures, revtex; final version, improved styl
Investigation of Weibull statistics in fracture analysis of cast aluminum
The fracture strengths of two large batches of A357-T6 cast aluminum coupon specimens were compared by using two-parameter Weibull analysis. The minimum number of these specimens necessary to find the fracture strength of the material was determined. The applicability of three-parameter Weibull analysis was also investigated. A design methodology based on the combination of elementary stress analysis and Weibull statistical analysis is advanced and applied to the design of a spherical pressure vessel shell. The results from this design methodology are compared with results from the applicable ASME pressure vessel code
Comparison of Weibull strength parameters from flexure and spin tests of brittle materials
Fracture data from five series of four point bend tests of beam and spin tests of flat annular disks were reanalyzed. Silicon nitride and graphite were the test materials. The experimental fracture strengths of the disks were compared with the predicted strengths based on both volume flaw and surface flaw analyses of four point bend data. Volume flaw analysis resulted in a better correlation between disks and beams in three of the five test series than did surface flaw analysis. The Weibull (moduli) and characteristic gage strengths for the disks and beams were also compared. Differences in the experimental Weibull slopes were not statistically significant. It was shown that results from the beam tests can predict the fracture strength of rotating disks
Quantum Kinetic Theory III: Simulation of the Quantum Boltzmann Master Equation
We present results of simulations of a em quantum Boltzmann master equation
(QBME) describing the kinetics of a dilute Bose gas confined in a trapping
potential in the regime of Bose condensation. The QBME is the simplest version
of a quantum kinetic master equations derived in previous work. We consider two
cases of trapping potentials: a 3D square well potential with periodic boundary
conditions, and an isotropic harmonic oscillator. We discuss the stationary
solutions and relaxation to equilibrium. In particular, we calculate particle
distribution functions, fluctuations in the occupation numbers, the time
between collisions, and the mean occupation numbers of the one-particle states
in the regime of onset of Bose condensation.Comment: 12 pages, 15 figure
Absence of evidence for pentaquarks on the lattice
We study the question of whether or not QCD predicts a pentaquark state. We
use the improved, fixed point lattice QCD action which has very little
sensitivity to the lattice spacing and also allows us to reach light quark
masses. The analysis was performed on a single volume of size with lattice spacing of fm. We use the
correlation matrix method to identify the ground and excited states in the
isospin 0, negative parity channel. In the quenched approximation where
dynamical quark effects are omitted, we do not find any evidence for a
pentaquark resonance in QCD.Comment: 17 pages, 5 figures replaced with revised versio
The SUMMIT trial: a field comparison of buprenorphine versus methadone maintenance treatment.
This prospective patient-preference study examined the effectiveness in practice of methadone versus buprenorphine maintenance treatment and the beliefs of subjects regarding these drugs. A total of 361 opiate-dependent individuals (89% of those eligible, presenting for treatment over 2 years at a drug service in England) received rapid titration then flexible dosing with methadone or buprenorphine; 227 patients chose methadone (63%) and 134 buprenorphine (37%). Participants choosing methadone had more severe substance abuse and psychiatric and physical problems but were more likely to remain in treatment. Survival analysis indicated those prescribed methadone were over twice as likely to be retained (hazard ratio for retention was 2.08 and 95% confidence interval [CI] = 1.49-2.94 for methadone vs. buprenorphine), However, those retained on buprenorphine were more likely to suppress illicit opiate use (odds ratio = 2.136, 95% CI = 1.509-3.027, p < .001) and achieve detoxification. Buprenorphine may also recruit more individuals to treatment because 28% of those choosing buprenorphine (10% of the total sample) stated they would not have accessed treatment with methadone
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Numerical modelling of microwave sintering of lunar simulants under near lunar atmospheric condition
Undamped nonequilibrium dynamics of a nondegenerate Bose gas in a 3D isotropic trap
We investigate anomalous damping of the monopole mode of a non-degenerate 3D
Bose gas under isotropic harmonic confinement as recently reported by the JILA
TOP trap experiment [D. S. Lob- ser, A. E. S. Barentine, E. A. Cornell, and H.
J. Lewandowski (in preparation)]. Given a realistic confining potential, we
develop a model for studying collective modes that includes the effects of
anharmonic corrections to a harmonic potential. By studying the influence of
these trap anharmonicities throughout a range of temperatures and collisional
regimes, we find that the damping is caused by the joint mechanisms of
dephasing and collisional relaxation. Furthermore, the model is complimented by
Monte Carlo simulations which are in fair agreement with data from the JILA
experiment.Comment: 11 pages, 6 figure
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