1,051 research outputs found
The equation of state and symmetry energy of low density nuclear matter
The symmetry energy of nuclear matter is a fundamental ingredient in the
investigation of exotic nuclei, heavy-ion collisions and astrophysical
phenomena. A recently developed quantum statistical (QS) approach that takes
the formation of clusters into account predicts low density symmetry energies
far above the usually quoted mean field limits. A consistent description of the
symmetry energy has been developed that joins the correct low-density limit
with values calculated from quasi-particle approaches valid near the saturation
density. The results are confronted with experimental values for free symmetry
energies and internal symmetry energies, determined at sub-saturation densities
and temperatures below 10 MeV using data from heavy-ion collisions. There is
very good agreement between the experimental symmetry energy values and those
calculated in the QS approachComment: 16 pages, 10 figures. arXiv admin note: text overlap with
arXiv:0908.234
Five Years Under the Veterans Judicial Review Act: The VA is Brought Kicking and Screaming into the World of Meaningful Due Process
I have been asked to give you the “veterans\u27 perspective” on whether the Court of Veterans Appeals has served the purpose for which it was created by Congress and also to describe what additional steps the court might take to further the ends desired by veterans. This is no easy task. It is difficult not because I do not have a lot to say. It is difficult because it is a charge to speak, in a sense, for all veterans. In order to understand what I mean, I think it may be helpful to give you a little background on the view of the veterans community regarding judicial review. There are forty veterans service organizations recognized by the Department of Veterans Affairs (VA). These organizations range from the smallest, the Congressional Medal of Honor Society, to the largest, the American Legion, which boasts 3.2 million members. The Paralyzed Veterans of America, of which I am the General Counsel, fits somewhere in the middle. In addition, there are other small organizations of veterans which do not have official VA recognition. In all, these organizations speak for some twenty-seven million veterans of the United States Armed Forces. The number of veterans organizations gives you an idea of the diversity of interests of veterans. There is complete unanimity of opinion on few issues affecting the veterans community. Judicial review is an example
Nucleation and cluster formation in low-density nucleonic matter: A mechanism for ternary fission
Ternary fission yields in the reaction 241Pu(nth,f) are calculated using a
new model which assumes a nucleation-time moderated chemical equilibrium in the
low density matter which constitutes the neck region of the scissioning system.
The temperature, density, proton fraction and fission time required to fit the
experimental data are derived and discussed. A reasonably good fit to the
experimental data is obtained. This model provides a natural explanation for
the observed yields of heavier isotopes relative to those of the lighter
isotopes, the observation of low proton yields relative to 2H and 3H yields and
the non-observation of 3He, all features which are shared by similar thermal
neutron induced and spontaneous fissioning systems.Comment: 6 pages, 3 figure
Isocaling and the Symmetry Energy in the Multifragmentation Regime of Heavy Ion Collisions
The ratio of the symmetry energy coefficient to temperature, , in
Fermi energy heavy ion collisions, has been experimentally extracted as a
function of the fragment atomic number using isoscaling parameters and the
variance of the isotope distributions. The extracted values have been compared
to the results of calculations made with an Antisymmetrized Molecular Dynamics
(AMD) model employing a statistical decay code to account for deexcitation of
excited primary fragments. The experimental values are in good agreement with
the values calculated but are significantly different from those characterizing
the yields of the primary AMD fragments.Comment: 12 pages, 6 figure
Symmetry energy of dilute warm nuclear matter
The symmetry energy of nuclear matter is a fundamental ingredient in the
investigation of exotic nuclei, heavy-ion collisions and astrophysical
phenomena. New data from heavy-ion collisions can be used to extract the free
symmetry energy and the internal symmetry energy at subsaturation densities and
temperatures below 10 MeV. Conventional theoretical calculations of the
symmetry energy based on mean-field approaches fail to give the correct
low-temperature, low-density limit that is governed by correlations, in
particular by the appearance of bound states. A recently developed quantum
statistical (QS) approach that takes the formation of clusters into account
predicts symmetry energies that are in very good agreement with the
experimental data. A consistent description of the symmetry energy is given
that joins the correct low-density limit with quasiparticle approaches valid
near the saturation density.Comment: 4 pages, 2 figures, 1 tabl
Voluntary Risk Taking By Young Bicyclists:A Case Study of University Students at Montreal
Young bicyclists in Montreal are taking voluntary risks such as bicycling without wearing helmet and braking system of bicycle although they are aware of the presence of danger. This article analyses the behaviour of young bicyclists taking voluntary risks. The university students in Montreal are considered as the case study since they are more risk takers and the bicycle is a favorite mode of transport among them. This study reveals that half of the respondents did not use helmets. They were also spontaneously taking a risk by high speeding, violating signals, bicycling in mixed traffic, ignoring protective equipment after dark, and avoiding the bicycle designated roads. They were taking voluntary risks based on their attitude, subjective norm and perceived behavioural control. They did not perceive the severity of risks since they experienced relevant and unremarkable minor injuries. The attractiveness of risk and accomplishing the risk activities encouraged the young bicyclists to take voluntary risks repeatedly. Increasing feelings of vulnerability among young bicyclists reduce voluntary risks taking attitude and physical and psychological sufferings of the victims of bicycle-related accidents. Findings of this study suggest that the City of Montreal as well as other cities consider the behaviour of bicyclists particularly the young people to avoid bicycle-related accidents along with other physical measures
Density determinations in heavy ion collisions
The experimental determination of freeze-out temperatures and densities from
the yields of light elements emitted in heavy ion collisions is discussed.
Results from different experimental approaches are compared with those of model
calculations carried out with and without the inclusion of medium effects.
Medium effects become of relevance for baryon densities above fm. A quantum statistical (QS) model incorporating medium
effects is in good agreement with the experimentally derived results at higher
densities. A densitometer based on calculated chemical equilibrium constants is
proposed.Comment: 5 pages, 3 figure
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