548 research outputs found
Uniqueness of bounded solutions for the homogeneous Landau equation with a Coulomb potential
We prove the uniqueness of bounded solutions for the spatially homogeneous
Fokker-Planck-Landau equation with a Coulomb potential. Since the local (in
time) existence of such solutions has been proved by Arsen'ev-Peskov (1977), we
deduce a local well-posedness result. The stability with respect to the initial
condition is also checked
Tightness for a stochastic Allen--Cahn equation
We study an Allen-Cahn equation perturbed by a multiplicative stochastic
noise which is white in time and correlated in space. Formally this equation
approximates a stochastically forced mean curvature flow. We derive uniform
energy bounds and prove tightness of of solutions in the sharp interface limit,
and show convergence to phase-indicator functions.Comment: 27 pages, final Version to appear in "Stochastic Partial Differential
Equations: Analysis and Computations". In Version 4, Proposition 6.3 is new.
It replaces and simplifies the old propositions 6.4-6.
Nuclear Alpha-Particle Condensates
The -particle condensate in nuclei is a novel state described by a
product state of 's, all with their c.o.m. in the lowest 0S orbit. We
demonstrate that a typical -particle condensate is the Hoyle state
( MeV, state in C), which plays a crucial role for
the synthesis of C in the universe. The influence of antisymmentrization
in the Hoyle state on the bosonic character of the particle is
discussed in detail. It is shown to be weak. The bosonic aspects in the Hoyle
state, therefore, are predominant. It is conjectured that -particle
condensate states also exist in heavier nuclei, like O,
Ne, etc. For instance the state of O at MeV
is identified from a theoretical analysis as being a strong candidate of a
condensate. The calculated small width (34 keV) of ,
consistent with data, lends credit to the existence of heavier Hoyle-analogue
states. In non-self-conjugated nuclei such as B and C, we discuss
candidates for the product states of clusters, composed of 's,
triton's, and neutrons etc. The relationship of -particle condensation
in finite nuclei to quartetting in symmetric nuclear matter is investigated
with the help of an in-medium modified four-nucleon equation. A nonlinear order
parameter equation for quartet condensation is derived and solved for
particle condensation in infinite nuclear matter. The strong qualitative
difference with the pairing case is pointed out.Comment: 71 pages, 41 figures, review article, to be published in "Cluster in
Nuclei (Lecture Notes in Physics) - Vol.2 -", ed. by C. Beck,
(Springer-Verlag, Berlin, 2011
The Enskog Process
The existence of a weak solution to a McKean-Vlasov type stochastic
differential system corresponding to the Enskog equation of the kinetic theory
of gases is established under natural conditions. The distribution of any
solution to the system at each fixed time is shown to be unique. The existence
of a probability density for the time-marginals of the velocity is verified in
the case where the initial condition is Gaussian, and is shown to be the
density of an invariant measure.Comment: 38 page
On-site underground background measurements for the KASKA reactor-neutrino experiment
On-site underground background measurements were performed for the planned
reactor-neutrino oscillation experiment KASKA at Kashiwazaki-Kariwa nuclear
power station in Niigata, Japan. A small-diameter boring hole was excavated
down to 70m underground level, and a detector unit for -ray and
cosmic-muon measurements was placed at various depths to take data. The data
were analyzed to obtain abundance of natural radioactive elements in the
surrounding soil and rates of cosmic muons that penetrate the overburden. The
results will be reflected in the design of the KASKA experiment.Comment: 9 pages, 7 figures, final version for publication. Table 1 and Fig.5
have change
A project on magnetic survey in Bransfield Strait, Antarctic Peninsula
第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月16日(水) 国立国語研究所 2階フロ
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