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March 13, 2013

Pascal Chossat is a professor in the Mathematics Department at the University of Nice, France. He is an author, researcher, and leader in his field.

3-5 p.m.

Hammond Auditorium

Engineering Building, Room 120

The Arne Magnus lectures are given annually in the Department of Mathematics at Colorado State University in honor of Professor Arne Magnus, a friend and colleague for 25 years. The lectures are supported by the Arne Magnus Lecture Fund and the Albert C. Yates Endowment in Mathematics.

The 2013 speaker is Pascal Chossat, Ph.D., Director of Research in the Department of Mathematics at the University of Nice and French National Center for Scientific Research. He is also an Adjoint Director of the National Institute of Mathematical Sciences, NCRS.

Chossat will speak on, "Bifurcation and symmetry, a mathematical view on pattern formation in nature.”

"Patterns in nature are not of so many types. The coat of a zebra is stripped while the coat of a leopard is spotted (and a cougar has a uniformly colored fur). Honey bees build incredibly regular hexagonal cells.

"Many plants or sea organisms present a high degree of symmetry, like the icosahedral shell of certain radiolarians. These quite simple patterns are extremely common, not only with living creatures but also in inanimate matter, think of the regular patterns in crystals like the cubic symmetry of salt for example, or the spiral patterns which can form on the heart muscle and provoke a heart attack.

"The common denominator of these examples is the underlying mathematics, which model the formation of regular patterns. Although more complex patterns have recently been observed, like quasi-crystals, the mathematical theory of pattern formation, which was initiated by the celebrated mathematician Alan Turing, is an example of the 'unreasonable effectiveness of mathematics in natural science,' as Nobel Prize winner Eugene Wigner used to say.

A reception will follow the lecture in 117 Weber Building from 4-5:30 p.m.

Thursday, March 14, 11-11:50 p.m.

237 Weber Building

A colloquium will be held that is open to faculty and graduate students. The title is, "Pattern formation on compact Riemann surfaces and applications".

"Pattern formation on the sphere and torus has been widely studied in relation to the occurrence of periodic patterns in classical hydrodynamical systems and in biochemical models of reaction-diffusion equations.

Recently a model for images texture perception by the visual cortex was introduced, which involves neural field equations posed on the hyperbolic plane.

Looking for pattern formation in this non euclidean geometric context comes back to analyzing the bifurcation of patterns on compact Riemann surfaces of genus > 1. This leads to new and sometimes unexpected results, which open the door to a classification of patterns on Riemann surfaces."

Tea time reception prior to talk will be held in 117 Weber Building, 10:30-11 a.m.

Contact: Christie Franklin

E-mail: franklin@math.colostate.edu

Phone: (970) 491-6452

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