2,379 research outputs found
Debye mass and heavy quark potential in a PNJL quark plasma
We calculate the Debye mass for the screening of the heavy quark potential in
a plasma of massless quarks coupled to the temporal gluon background governed
by the Polyakov loop potential within the PNJL model in RPA approximation. We
give a physical motivation for a recent phenomenological fit of lattice data by
applying the calculated Debye mass with its suppression in the confined phase
due to the Polyakov-loop to a description of the temperature dependence of the
singlet free energy for QCD with a heavy quark pair at infinite separation. We
compare the result to lattice data.Comment: 6 pages, 1 figure, contribution to Proceedings of the 6th
International Conference on "Critical Point and Onset of Deconfinement", to
appear in Phys. At. Nucl., vol. 7
Self Assembled Clusters of Spheres Related to Spherical Codes
We consider the thermodynamically driven self-assembly of spheres onto the
surface of a central sphere. This assembly process forms self-limiting, or
terminal, anisotropic clusters (N-clusters) with well defined structures. We
use Brownian dynamics to model the assembly of N-clusters varying in size from
two to twelve outer spheres, and free energy calculations to predict the
expected cluster sizes and shapes as a function of temperature and inner
particle diameter. We show that the arrangements of outer spheres at finite
temperatures are related to spherical codes, an ideal mathematical sequence of
points corresponding to densest possible sphere packings. We demonstrate that
temperature and the ratio of the diameters of the inner and outer spheres
dictate cluster morphology and dynamics. We find that some N-clusters exhibit
collective particle rearrangements, and these collective modes are unique to a
given cluster size N. We present a surprising result for the equilibrium
structure of a 5-cluster, which prefers an asymmetric square pyramid
arrangement over a more symmetric arrangement. Our results suggest a promising
way to assemble anisotropic building blocks from constituent colloidal spheres.Comment: 15 pages, 10 figure
Limits on the Mass, Velocity and Orbit of PSR J19336211
We present a high-precision timing analysis of PSR J19336211, a
millisecond pulsar (MSP) with a 3.5-ms spin period and a white dwarf (WD)
companion, using data from the Parkes radio telescope. Since we have accurately
measured the polarization properties of this pulsar we have applied the matrix
template matching approach in which the times of arrival are measured using
full polarimetric information. We achieved a weighted root-mean-square timing
residuals (rms) of the timing residuals of 1.23 , 15.5
improvement compared to the total intensity timing analysis. After studying the
scintillation properties of this pulsar we put constraints on the inclination
angle of the system. Based on these measurements and on mapping we put
a 2- upper limit on the companion mass (0.44 M). Since this
mass limit cannot reveal the nature of the companion we further investigate the
possibility of the companion to be a He WD. Applying the orbital period-mass
relation for such WDs, we conclude that the mass of a He WD companion would be
about 0.260.01 M which, combined with the measured mass function
and orbital inclination limits, would lead to a light pulsar mass
1.0 M. This result seems unlikely based on current neutron star
formation models and we therefore conclude that PSR J19336211 most likely
has a CO WD companion, which allows for a solution with a more massive pulsar
Emerging considerations in the reversal of neuromuscular blockade and residual block
Incomplete recovery following reversal of neuromuscular blockade can present as a clinical problem in surgical patients. Emerging pharmacologic solutions may prevent such adverse outcomes in the future. We briefly review two methods of pharmacologic reversal of neuromuscular blockade. Both methods of reversal are effective. However the early studies of the new compound, sugammadex has been shown to achieve a more rapid, stable reversal of steroidal based neuromuscular blocking agents compared to neostigmine. Due to the novel mechanism of action of this agent, sugammadex has been demonstrated to be effective even when administered during profound neuromuscular block, without evidence of recurarization
The influence of waters from hard-coal mines on the hydrochemical relations of Upper Silesian Coal Basin (USCB) rivers
Surface waters of the Upper Silesian Coal Basin (USCB) are highly transformed in quality as a consequence of salty minewater discharge to the hydrographic net. These waters drain coal beds which are extracted to a depth of 1000 m. The amount of minewater, discharging directly or indirectly to the river net of the USCB
reaches 8-9 m3/s with a variability in particular years of 1-1.5 m3/s, which depends on hydrological conditions of the levels extracted. In 1994, the salt load introduced together with these waters to the Vistula and the Oder reached 6793 tons per 24 hours of chloride ions and 1351 tons per 24 hours of sulphate ions. This accounted for over 50% of the chlorides and about 35% of the sulphates discharged to surface waters in the country.
Furthermore, a part of the minewater also contains radioactive elements (radium22 ). The chance to improve the quality of the Oder and Vistula waters in the nearest future is meagre
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