10,741 research outputs found
Phase transition for the frog model
We study a system of simple random walks on graphs, known as frog model. This
model can be described as follows: There are active and sleeping particles
living on some graph G. Each active particle performs a simple random walk with
discrete time and at each moment it may disappear with probability 1-p. When an
active particle hits a sleeping particle, the latter becomes active. Phase
transition results and asymptotic values for critical parameters are presented
for Z^d and regular trees
Evolution of isolated neutron stars in globular clusters: number of Accretors
With a simple model from the point of view of population synthesis we try to
verify an interesting suggestion made by Pfahl & Rappaport (2001) that dim
sources in globular clusters (GCs) can be isolated accreting neutron stars
(NSs). Simple estimates show, that we can expect about 0.5-1 accreting isolated
NS per typical GC with in correspondence with observations.
Properties of old accreting isolated NSs in GCs are briefly discussed. We
suggest that accreting NSs in GCs experienced significant magnetic field decay.Comment: 6 pages, no figures. Submitted to Astronomical and Astrophysical
Transactions (style included
Comment on "Four-body charge transfer processes in proton--helium collisions"
We found, within the plane-wave first Born approximation (PWFBA), that the
proton-helium fully differential cross section (FDCS) for transfer excitation
agrees well with the experimental one at the proton energy Ep = 300 keV and
small scattering angles both in shape and in magnitude. This result is in a
contradiction with that obtained in [1].Comment: 4 pages, 2 figure
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