22,363 research outputs found
Scaled Particle Theory for Hard Sphere Pairs. II. Numerical Analysis
We use the extension of scaled particle theory (ESPT) presented in the
accompanying paper [Stillinger et al. J. Chem. Phys. xxx, xxx (2007)] to
calculate numerically pair correlation function of the hard sphere fluid over
the density range . Comparison with computer
simulation results reveals that the new theory is able to capture accurately
the fluid's structure across the entire density range examined. The pressure
predicted via the virial route is systematically lower than simulation results,
while that obtained using the compressibility route is lower than simulation
predictions for and higher than simulation predictions
for . Numerical predictions are also presented for the
surface tension and Tolman length of the hard sphere fluid
Thermal photons from fluctuating initial conditions
Event-by-event fluctuations of initial QCD-matter density produced in
heavy-ion collisions at RHIC enhance the production of thermal photons
significantly in the region GeV/ compared to a smooth
initial-state averaged profile in the ideal hydrodynamic calculation. This
enhancement is a an early time effect due to the presence of hotspots or
over-dense regions in the fluctuating initial state. The effect of fluctuations
is found to be stronger in peripheral than in central collisions.Comment: 4 pages, 3 figures. Talk given at Quark Matter 2011, 22-28 May 2011,
Annecy, Franc
Strong CP violation and chiral symmetry breaking in hot and dense quark matter
We investigate chiral symmetry breaking and strong CP violation effects in
the phase diagram of strongly interacting matter. We demonstrate the effect of
strong CP violating terms on the phase structure at finite temperature and
densities in a 3-flavor Nambu-Jona-Lasinio (NJL) model including the
Kobayashi-Maskawa-t'Hooft (KMT) determinant term. This is investigated using an
explicit structure for the ground state in terms of quark-antiquark condensates
for both in the scalar and the pseudoscalar channels. CP restoring transition
with temperature at zero baryon density is found to be a second order
transition at while the same at finite chemical potential and
small temperature turns out to be a first order transition. Within the model,
the tri-critical point turns out to be MeV at
for such a transition.Comment: 10 pages, 12 figure
Radially restricted linear energy transfer for high-energy protons: A new analytical approach
Radially restricted linear energy transfer (LET) is a basic physical parameter relevant to radiation biology and radiation protection. In this report a convenient method is presented for the analytical computation of this quantity without the need for complicated simulation. The method uses the energy-re-stricted LETL, as recently redefined in a 1993 ICRU draft document and supplements it by a relatively simple term that represents the energy of fast rays lost within distancer from the track core. The method provides a better fit than other models and is valid over the entire range of radial distance from track center to the maximum radial distance traveled by the most energetic secondary electrons.L r computed by this approach differs only a few percent from the values
Contribution to the international symposium on heavy ions research: space, radiation protection and therapy, 21–24 March 1994, Sophia-Antipolis, Franc
First excited state calculation using different phonon bases for the two-site Holstein model
The single-electron energy and static charge-lattice deformation correlations
have been calculated for the first excited state of a two-site Holstein model
within perturbative expansions using different standard phonon bases obtained
through Lang-Firsov (LF) transformation, LF with squeezed phonon states,
modified LF, modified LF transformation with squeezed phonon states, and also
within weak-coupling perturbation approach. Comparisons of the convergence of
the perturbative expansions for different phonon bases reveal that modified LF
approach works much better than other approaches for major range of the
coupling strength.Comment: 11 pages (REVTEX), 4 postscript figure
Enhanced Cluster Based Routing Protocol for MANETS
Mobile ad-hoc networks (MANETs) are a set of self organized wireless mobile
nodes that works without any predefined infrastructure. For routing data in
MANETs, the routing protocols relay on mobile wireless nodes. In general, any
routing protocol performance suffers i) with resource constraints and ii) due
to the mobility of the nodes. Due to existing routing challenges in MANETs
clustering based protocols suffers frequently with cluster head failure
problem, which degrades the cluster stability. This paper proposes, Enhanced
CBRP, a schema to improve the cluster stability and in-turn improves the
performance of traditional cluster based routing protocol (CBRP), by electing
better cluster head using weighted clustering algorithm and considering some
crucial routing challenges. Moreover, proposed protocol suggests a secondary
cluster head for each cluster, to increase the stability of the cluster and
implicitly the network infrastructure in case of sudden failure of cluster
head.Comment: 6 page
Scaled Particle Theory for Hard Sphere Pairs. I. Mathematical Structure
We develop an extension of the original Reiss-Frisch-Lebowitz scaled particle
theory that can serve as a predictive method for the hard sphere pair
correlation function g(r). The reversible cavity creation work is analyzed both
for a single spherical cavity of arbitrary size, as well as for a pair of
identical such spherical cavities with variable center-to-center separation.
These quantities lead directly to prediction of g(r). Smooth connection
conditions have been identified between the small-cavity situation where the
work can be exactly and completely expressed in terms of g(r), and the
large-cavity regime where macroscopic properties become relevant. Closure
conditions emerge which produce a nonlinear integral equation that must be
satisfied by the pair correlation function. This integral equation has a
structure which straightforwardly generates a solution that is a power series
in density. The results of this series replicate the exact second and third
virial coefficients for the hard sphere system via the contact value of the
pair correlation function. The predicted fourth virial coefficient is
approximately 0.6 percent lower than the known exact value. Detailed numerical
analysis of the nonlinear integral equation has been deferred to the sequel
(following paper
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