ELFT HÍRADÓ

[StatFizSzeminar <statfiz AT glu.elte.hu>]

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                   ELTE Institute of Physics
                SEMINARS IN STATISTICAL PHYSICS


                        16th March 2016
                       Wednesday, 11 a.m.

                         Ulrike Feudel

           Theoretical Physics/Complex Systems, ICBM,
      Carl von Ossietzky University of Oldenburg, Germany

 "Self-induced switchings between multiple space-time patterns
             on complex networks of excitable units"


We report on self-induced switchings between multiple distinct space-time 
patterns
in the dynamics of a spatially extended excitable system. These switchings 
between
low-amplitude oscillations, nonlinear waves, and extreme events strongly 
resemble a
random process, although the system is deterministic. We show that a chaotic
saddle --- which contains all the patterns as well as channel-like structures 
that
mediate the transitions between them --- is the backbone of such a pattern 
switching
dynamics. Our analyses indicate that essential ingredients for the observed
phenomena are that the system behaves like an inhomogeneous oscillatory medium
that is capable of self-generating spatially localized excitations and that 
is dominated
by short-range connections but also features long-range connections. With our
findings, we present an alternative to the well-known ways to obtain 
self-induced
pattern switching, namely noise-induced attractor hopping, heteroclinic 
orbits,
and adaptation to an external signal. This alternative way can be expected to
improve our understanding of pattern switchings in spatially extended natural
dynamical systems like the brain and the heart.


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