4,337 research outputs found
Non-homogeneous random walks, subdiffusive migration of cells and anomalous chemotaxis
This paper is concerned with a non-homogeneous in space and non-local in time
random walk model for anomalous subdiffusive transport of cells. Starting with
a Markov model involving a structured probability density function, we derive
the non-local in time master equation and fractional equation for the
probability of cell position. We show the structural instability of fractional
subdiffusive equation with respect to the partial variations of anomalous
exponent. We find the criteria under which the anomalous aggregation of cells
takes place in the semi-infinite domain.Comment: 18 pages, accepted for publicatio
Creation of electron-positron plasma with superstrong laser field
We present a short review of recent progress in studying QED effects of
interaction of ultra-relativistic laser pulses with vacuum and plasma.
The development of laser technologies promises very rapid growth of laser
intensities in close future already. Two exawatt class facilities (ELI and
XCELS, Russia) in Europe are already in the planning stage. Realization of
these projects will make available a laser of intensity W/cm
or even higher. Therefore, discussion of nonlinear optical effects in vacuum
are becoming urgent for experimentalists and are currently gaining much
attention. We show that, in spite of the fact that the respective field
strength is still essentially less than V/cm, the nonlinear vacuum effects will be accessible for observation
at ELI and XCELS facilities. The most promissory for observation is the effect
of pair creation by laser pulse in vacuum. It is shown, that at intensities
W/cm, creation even of a single pair is accompanied by
development of an avalanchelike QED cascade. There exists an important
distinctive feature of the laser-induced cascades, as compared with the air
showers arising due to primary cosmic ray entering the atmosphere. In our case
the laser field plays not only the role of a target (similar to a nucleus in
the case of air showers). It is responsible also for acceleration of slow
particles. It is shown that the effect of pair creation imposes a natural limit
for attainable laser intensity. Apparently, the field strength is
not accessible for pair creating electromagnetic field at all.Comment: To be published in digest "IZEST Scientific Case" in EPJ ST early
201
On eigenfunction approximations for typical non-self-adjoint Schroedinger operators
We construct efficient approximations for the eigenfunctions of
non-self-adjoint Schroedinger operators in one dimension. The same ideas also
apply to the study of resonances of self-adjoint Schroedinger operators which
have dilation analytic potentials. In spite of the fact that such
eigenfunctions can have surprisingly complicated structures with multiple local
maxima, we show that a suitable adaptation of the JWKB method is able to
provide accurate lobal approximations to them.Comment: 17 pages, 11 figure
Projections of potential luminosity improvement for low-energy RHIC operation with electron cooling
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