4,154 research outputs found
Experimental verification and practical application of torquewhirl theory of rotordynamic instability
A theory developed by Vance in 1978 to explain the destabilizing effect of torque on a whirling rotor was experimentally verified. The measurements made on a specially designed test apparatus are described. New computer models were also developed to investigate the effect of torque on rotordynamic stability of multidisk flexible rotor bearing systems. The effect of torque was found to be most pronounced when the system is already marginally stable from other influences. The modifications required to include torque in a typical shaft transfer matrix are described, and results are shown which identify the type of rotor design most sensitive to load torque
Strange hyperon and antihyperon production from quark and string-rope matter
Hyperon and antihyperon production is investigated using two microscopical
models: {\bf (1)} the fast hadronization of quark matter as given by the ALCOR
model; {\bf (2)} string formation and fragmentation as in the HIJING/B model.
We calculate the particle numbers and momentum distributions for Pb+Pb
collisions at CERN SPS energies in order to compare the two models with each
other and with the available experimental data. We show that these two
theoretical approaches give similar yields for the hyperons, but strongly
differ for antihyperons.Comment: 11 pages, Latex, 3 EPS figures, contribution to the Proceedings of
the 4th International Conference on Strangeness in Quark Matter (SQM'98),
Padova, Italy, 20-24 July 199
Significant in-medium reduction of the mass of eta' mesons in sqrt(s(NN)) = 200 GeV Au+Au collisions
PHENIX and STAR data on the intercept parameter of the two-pion Bose-Einstein
correlation functions in GeV Au+Au collisions were
analysed in terms of various models of hadronic abundances. To describe these
data, an in-medium mass decrease of at least 200 MeV was needed
in each case.Comment: Dedicated to 60th birthday of Miklos Gyulassy. 2 pages, 4 figures -
To appear in the conference proceedings for Quark Matter 2009, March 30 -
April 4, Knoxville, Tennesse
A method of eta' decay product selection to study partial chiral symmetry restoration
In case of chiral U_A(1) symmetry restoration the mass of the eta' boson (the
ninth, would-be Goldstone boson) is decreased, thus its production cross
section is heavily enhanced. The eta' decays (through one of its decay
channels) into five pions. These pions will not be correlated in terms of
Bose-Einsten correlations, thus the production enhancement changes the strength
of two-pion correlation functions at low momentum. Preliminary results strongly
support the mass decrease of the eta' boson. In this paper we propose a method
to select pions coming from eta' decays. We investigate the efficiency of the
proposed kinematical cut in several collision systems and energies with several
simulators. We prove that our method can be used in all investigeted collision
systems.Comment: Talk at the VI Workshop on Particle Correlations and Femtoscopy,
Kiev, September 14-18, 2010. 6 pages, 3 figures. This work was supported by
the OTKA grant NK73143 and M. Csanad's Bolyai scholarshi
Comparison of Fibroblast and Vascular Cell Adhesion to Nano-Structured Poly(lactic-co-glycolic acid) Films
The Effects of Acute Creatine Supplementation on Arterial Stiffness
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Anti-Hyperon Enhancement through Baryon Junction Loops
The baryon junction exchange mechanism recently proposed to explain valence
baryon number transport in nuclear collisions is extended to study midrapidity
anti-hyperon production. Baryon junction-anti-junction (J anti-J) loops are
shown to enhance anti-Lambda, anti-Xi, anti-Omega yields as well as lead to
long range rapidity correlations. Results are compared to recent WA97 Pb + Pb
-> Y + anti-Y + X data.Comment: 10 pages, 4 figure
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A 2000-year annual record of snow accumulation rates for Law Dome, East Antarctica
Accurate high-resolution records of snow accumulation rates in Antarctica are crucial for estimating ice sheet mass balance and subsequent sea level change. Snowfall rates at Law Dome, East Antarctica, have been linked with regional atmospheric circulation to the mid-latitudes as well as regional Antarctic snowfall. Here, we extend the length of the Law Dome accumulation record from 750 years to 2035 years, using recent annual layer dating that extends to 22 BCE. Accumulation rates were calculated as the ratio of measured to modelled layer thicknesses, multiplied by the long-term mean accumulation rate. The modelled layer thicknesses were based on a power-law vertical strain rate profile fitted to observed annual layer thickness. The periods 380–442, 727–783 and 1970–2009 CE have above-average snow accumulation rates, while 663–704, 933–975 and 1429–1468 CE were below average, and decadal-scale snow accumulation anomalies were found to be relatively common (74 events in the 2035-year record). The calculated snow accumulation rates show good correlation with atmospheric reanalysis estimates, and significant spatial correlation over a wide expanse of East Antarctica, demonstrating that the Law Dome record captures larger-scale variability across a large region of East Antarctica well beyond the immediate vicinity of the Law Dome summit. Spectral analysis reveals periodicities in the snow accumulation record which may be related to El Niño–Southern Oscillation (ENSO) and Interdecadal Pacific Oscillation (IPO) frequencies
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