110,647 research outputs found
On some properties of a class of multivariate Erlang mixtures with insurance applications
We discuss some properties of a class of multivariate mixed Erlang distributions with different scale parameters and describes various distributional properties related to applications in insurance risk theory. Some representations involving scale mixtures, generalized Esscher transformations, higher-order equilibrium distributions, and residual lifetime distributions are derived. These results allows for the study of stop-loss moments, premium calculation, and the risk allocation problem. Finally, some results concerning minimum and maximum variables are derived and applied to pricing joint life and last survivor policies.postprin
Open Charm Production in an Equilibrating Parton Plasma
Open charm production during the equilibration of a gluon dominated parton
plasma is calculated, with both the time-dependent temperature and parton
densities given by a set of rate equations. Including pre-thermal production,
the total enhancement of open charm production over the initial gluon fusion
depends sensitively on the initial parton density and the effective
temperature. The dependence of the pre-thermal charm production on the
space-momentum correlation in the initial parton phase-space distribution is
also discussed.Comment: 23 pages REVTEX, 7 uuencoded postscript figures include
Growth and income distributions in four EU economies
Dynamic multi-sectoral and multi-household general equilibrium models are constructed to show how the economies of Germany, France, Spain and the United Kingdom will evolve from 2006 to 2090. These models generate dynamic paths of investment and capital accumulations, demand and supply across production sectors, consumption and welfare of households, relative prices of goods and services, revenue and expenditure of governments, exports, imports, and trade balance consistent with the dynamic general equilibrium in these economies. The models show that inequalities in income distribution among households will not decrease but widen if the current mix of direct and indirect taxes continues in all four countries. Growing inequalities in these economies justify further investments in education and skills
Growth states of catalytic reaction networks exhibiting energy metabolism
All cells derive nutrition by absorbing some chemical and energy resources
from the environment; these resources are used by the cells to reproduce the
chemicals within them, which in turn leads to an increase in their volume. In
this study, we introduce a protocell model exhibiting catalytic reaction
dynamics, energy metabolism, and cell growth. Results of extensive simulations
of this model show the existence of four phases with regard to the rates of
both the influx of resources and the cell growth. These phases include an
active phase with high influx and high growth rates, an inefficient phase with
high influx but low growth rates, a quasi-static phase with low influx and low
growth rates, and a death phase with negative growth rate. A mean field model
well explains the transition among these phases as bifurcations. The
statistical distribution of the active phase is characterized by a power law
and that of the inefficient phase is characterized by a nearly equilibrium
distribution. We also discuss the relevance of the results of this study to
distinct states in the existing cells.Comment: 21 pages, 5 figure
Direct Photons from Relativistic Heavy-Ion Collisions
Direct photons have been proposed as a promising signature for the
quark-gluon plasma (QGP) formation in relativistic heavy-ion collisions.
Recently WA98 presented the first data on direct photons in Pb+Pb-collisions at
SPS. At the same time RHIC started with its experimental program. The discovery
of the QGP in these experiments relies on a comparison of data with theoretical
predictions for QGP signals. In the case of direct photons new results for the
production rates of thermal photons from the QGP and a hot hadron gas as well
as for prompt photons from initial hard parton scatterings have been proposed
recently. Based on these rates a variety of different hydrodynamic models,
describing the space-time evolution of the fireball, have been adopted for
calculating the direct photon spectra. The results have been compared to the
WA98 data and predictions for RHIC and LHC have been made. So far the
conclusions of the various models are controversial.
The aim of the present review is to provide a comprehensive and up-to-date
survey and status report on the experimental and theoretical aspects of direct
photons in relativistic heavy-ion collisions.Comment: 91 pages, 44 figures, revised version to be published in Phys. Re
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