Buenos Dias!

Les hacemos una cordial invitación a la  plática de investigación que se llevará acabo el día  Viernes 5  de Marzo del 2010:

Ponente: Dra. Ulrike Feudel
                Universidad de Oldenburg de Alemania

Hora:  12:00 P.M

Lugar : Auditorio Daniel Malacara Hernández

Título: "Spatio Temporal Patterns Resulting from The interplay of biological Growth with Diffusion and Advection"


RESUMEN

        The interplay of nonlinear biological growth processes or chemical reactions with
physical transport processes like diffusion and advection can give rise to instabilities and
spatio-temporal pattern formation. We study the emergence of such patterns using
simple models of marine systems as a paradigm. First we investigate the conditions for
diffusion instabilities in a simplified model describing the dynamics of populations of
bacteria and its nutrient in sediments. The nutrients are transported passively by diffusion
and actively by bioirrigation. It is shown that under certain conditions Turing patterns can
occur which yield heterogeneous spatial patterns of species. These conditions for
instabilities are extended to include the competition between species. Furthermore, the
influence of the nonlocal bioirrigation transport on Turing patterns leads to the
coexistence of a variety of patterns, particularly to the emergence of “hot spots”, i.e.
localized regions of enhanced bacterial activity.
In the water column advection is the dominant physical process. We study the influence
of mesoscale hydrodynamic structures like vortices on biological growth processes in the
wake of an island. We consider a time-periodic two-dimensional flow using an analytical
stream function to mimic a velocity field which is characterized by a von Karman vortex
street as well as an Ekman flow perpendicular to it. Combining a Langragian approach
for the flow with an Eulerian approach for the concentration fields we show how the
upwelling of nutrients away from the island affects the evolution of plankton close to it.
In particular we employ concepts of Lagrangian chaos for the dynamics of particles in
time-dependent Hamiltonian systems to show that mesoscale vortices act as incubators

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