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Jan Burczak

Publications and source records attributed to Jan Burczak.

25 records · Page 2Linked to original sources
arXiv2015

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.

math.AP↗
arXiv2014

Boundedness of large-time solutions to a chemotaxis model with nonlocal and semilinear flux

A semilinear version of parabolic-elliptic Keller-Segel system with the \emph{critical} nonlocal diffusion is considered in one space dimension. We show boundedness of weak solutions under very general conditions on our semilinearity. It can degenerate, but has to provide a stronger dissipation for large values of a solution than in the critical linear case or we need to assume certain (explicit) data smallness. Moreover, when one considers a logistic term with a parameter $r$, we obtain our results even for diffusions slightly weaker than the critical linear one and for arbitrarily large initial datum, provided $r >1$. For a mild logistic dampening, we can improve the smallness condition on the initial datum up to $\sim \frac{1}{1-r}$.

math.AP↗
arXiv2012

L^{\infty} a priori bounds for gradients of solutions to quasilinear inhomogenous fast-growing parabolic systems

We prove boundedness of gradients of solutions to quasilinear parabolic system, the main part of which is a generalization to p-Laplacian and its right hand side's growth depending on gradient is not slower (and generally strictly faster) than p - 1. This result may be seen as a generalization to the classical notion of a controllable growth of right hand side, introduced by Campanato, over gradients of p-Laplacian-like systems. Energy estimates and nonlinear iteration procedure of a Moser type are cornerstones of the used method.

math.AP↗
arXiv2011

Does the fully parabolic quasilinear 1D Keller-Segel system enjoy long-time asymptotics analogous to its parabolic-elliptic simplification?

We show that the one-dimensional fully parabolic Keller-Segel system with nonlinear diffusion possesses global-in-time solutions, provided the nonlinear diffusion is equal to (1+u)^{-α}, for α< 1, independently on the volume of the initial data. We also show that in the critical case, i.e. for α= 1, the same result holds for initial masses smaller than a prescribed constant. Additionally, we prove existence of initial data for which solution blows up in a finite time for any nonlinear diffusion integrable at infinity. Thus we generalize the known blowup result of parabolic-elliptic case to the fully parabolic one. However, in the parabolic-elliptic case the above mentioned integrability condition on nonlinear diffusion sharply distinguishes between global existence and blowup cases. We are unable to recover the entire global existence counterpart of this result in a fully parabolic case.

math.AP↗