[Todos] coloquios extraordinarios

[pdmitruk en df.uba.ar]

La semana que viene visita el departamento Harry Swinney, profesor
de la Universidad de Texas at Austin, a quien la UBA le va a dar el  
doctorado honoris causa. Con motivo de esta visita se organizaron 2  
coloquios extraordinarios en el departamento, el lunes 15 y miercoles  
17 a las 16 hs, cuyos resumenes aqui se incluyen. Ademas, habra otra  
charla especial organizada
por la facultad el dia martes 16 a las 18 hs, luego de la ceremonia de  
entrega del titulo.

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Harry L. Swinney
Sid Richardson Foundation Regents Chair of Physics
University of Texas at Austin
http://chaos.utexas.edu/people/faculty/harry-l-swinney


Lunes 15 marzo, 2010, 16:00 Aula Federman, Pab. I

Fractal patterns in torn garbage bags, leaves, flowers, and water-oil
interfaces

Nature?s geometries include wavy edges that sometimes assume the
complex shapes called fractals, where a pattern repeats on different
scales. One family of such patterns includes the complex wavy
structures that are found along the edges of thin living tissues and
the edges of leaves (e.g., some lettuce). By applying simple growth
laws and principles from physics and geometry, it is possible to
understand how a thin flat leaf, flower, or plastic sheet can
spontaneously break symmetry and generate complex fractal patterns.
Similar fractal patterns form also when water from the underground
water table penetrates into an oil reservoir above it, as happens when
oil is pumped from the ground. A consequence of this ?viscous
fingering? is that only about half of the oil can be removed from a
reservoir. Viscous fingering patterns will be shown to exhibit
precisely the same mathematical properties as a simple computer model
that generates fractal structures.

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Miercoles  17 marzo, 2010, 16:00 Aula Federman, Pab. I

Deadly competition between bacterial colonies

A few bacteria on a surface (e.g., skin or a medical instrument) can
multiply rapidly and grow into a colony consisting of more than 10^9
bacteria and spanning several centimeters. What happens when
neighboring colonies of bacteria grow and approach one another? Our
research on a species of bacteria found in soil ??Paenibacillus
dendritiformis?? reveals that these bacteria mutually inhibit growth
through secretions that become lethal if the concentration exceeds a
well-defined threshold. Analysis of the secretions reveals the
presence of subtilisin (a protein that promotes growth) and a
previously unknown toxin, Slf (sibling lethal factor). An immediate
question is why doesn?t the toxin kill the bacteria secreting it? Our
group has developed a mathematical model that helps answer this
question. It is found that The gene that encodes Slf is homologous to
genes known to occur in many other bacteria; thus the mechanism
observed for self-regulation of growth of colonies of P.
dendritiformis may well occur in other bacteria.

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Martes 16 marzo , 2010, 18:00 Aula Magna, Pab. I

Ceremonia de entrega del titulo de Doctor Honoris causa.

Martes 16, 2010, 18:30 Aula Magna, Pab. I

Emergence of spatial patterns in physical, chemical, and biological systems

The emergence of patterns is one of the world?s most durable
mysteries. Some patterns ?clouds, snowflakes? form in space. Others
?the ebb and flow of tides, seasonal wet and dry spells? are patterns
that form in time. Natural patterns are mysterious because they are
complex, organized and interconnected, even though the laws of physics
on which they rest ? Newton?s classical laws of motion?are simple.
What do patterns such as the spirals in a frog egg, a fibrillating
heart, and an ocean eddy have in common? The sizes are vastly
different and the biology of even a simple frog egg is far more
complicated than the physics of a fluid. Yet, as this talk will show,
the patterns formed in such systems, differing widely in scale and in
the underlying molecular mechanisms, can in some cases be understood
from a common approach.