4,065 research outputs found
On the fractional Fisher information with applications to a hyperbolic-parabolic system of chemotaxis
We introduce new lower bounds for the fractional Fisher information. Equipped
with these bounds we study a hyperbolic-parabolic model of chemotaxis and prove
the global existence of solutions in certain dissipation regimes
On a drift-diffusion system for semiconductor devices
In this note we study a fractional Poisson-Nernst-Planck equation modeling a
semiconductor device. We prove several decay estimates for the Lebesgue and
Sobolev norms in one, two and three dimensions. We also provide the first term
of the asymptotic expansion as .Comment: to appear in Annales Henri Poincar\'
Global solutions for a hyperbolic-parabolic system of chemotaxis
We study a hyperbolic-parabolic model of chemotaxis in dimensions one and
two. In particular, we prove the global existence of classical solutions in
certain dissipation regimes
Boundedness and homogeneous asymptotics for a fractional logistic Keller-Segel equations
In this paper we consider a -dimensional () parabolic-elliptic
Keller-Segel equation with a logistic forcing and a fractional diffusion of
order . We prove uniform in time boundedness of its solution
in the supercritical range , where is an explicit
constant depending on parameters of our problem. Furthermore, we establish
sufficient conditions for , where
is the only nontrivial homogeneous solution. Finally, we
provide a uniqueness result
Critical Keller-Segel meets Burgers on : large-time smooth solutions
We show that solutions to the parabolic-elliptic Keller-Segel system on
with critical fractional diffusion
remain smooth for any initial data and any positive time. This disproves, at
least in the periodic setting, the large-data-blowup conjecture by Bournaveas
and Calvez. As a tool, we show smoothness of solutions to a modified critical
Burgers equation via a generalization of the method of moduli of continuity by
Kiselev, Nazarov and Shterenberg. over a setting where the considered equation
has no scaling. This auxiliary result may be interesting by itself. Finally, we
study the asymptotic behavior of global solutions, improving the existing
results.Comment: 17 page
Global solutions for a supercritical drift-diffusion equation
We study the global existence of solutions to a one-dimensional
drift-diffusion equation with logistic term, generalizing the classical
parabolic-elliptic Keller-Segel aggregation equation arising in mathematical
biology. In particular, we prove that there exists a global weak solution, if
the order of the fractional diffusion , where is
an explicit constant depending on the physical parameters present in the
problem (chemosensitivity and strength of logistic damping). Furthermore, in
the range with , the solution is globally
smooth. Let us emphasize that when , the diffusion is in the
supercritical regime
On a generalized doubly parabolic Keller-Segel system in one spatial dimension
We study a doubly parabolic Keller-Segel system in one spatial dimension,
with diffusions given by fractional laplacians. We obtain several local and
global well-posedness results for the subcritical and critical cases (for the
latter we need certain smallness assumptions). We also study dynamical
properties of the system with added logistic term. Then, this model exhibits a
spatio-temporal chaotic behavior, where a number of peaks emerge. In
particular, we prove the existence of an attractor and provide an upper bound
on the number of peaks that the solution may develop. Finally, we perform a
numerical analysis suggesting that there is a finite time blow up if the
diffusion is weak enough, even in presence of a damping logistic term. Our
results generalize on one hand the results for local diffusions, on the other
the results for the parabolic-elliptic fractional case
On turning waves for the inhomogeneous Muskat problem: a computer-assisted proof
We exhibit a family of graphs that develop turning singularities (i.e. their
Lipschitz seminorm blows up and they cease to be a graph, passing from the
stable to the unstable regime) for the inhomogeneous, two-phase Muskat problem
where the permeability is given by a nonnegative step function. We study the
influence of different choices of the permeability and different boundary
conditions (both at infinity and considering finite/infinite depth) in the
development or prevention of singularities for short time. In the general case
(inhomogeneous, confined) we prove a bifurcation diagram concerning the
appearance or not of singularities when the depth of the medium and the
permeabilities change. The proofs are carried out using a combination of
classical analysis techniques and computer-assisted verification.Comment: 30 pages, 6 figure
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