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Colloquium: Fall 2018


(Tenative Schedule)

Time & Location:  All talks are on Thursdays in Gibson Hall 325 at 3:30 pm unless otherwise noted.  Refreshments in Gibson 426 after the talk.
Comments indicating vacations, special lectures, or change in location or time are in green.

Organizer:  Gustavo Didier


September 6

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September 13

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September 20

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September 27

Geometry and topology of random curves

Igor RivinTemple University  (Host: Victor Moll)

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We study (experimentally and theoretically) random curves (in many senses) in space and in the plane, including such of their properties as the knot type.


October 4

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October 18

Symmetries and choreographies in the N-body problem

Renato Calleja National Autonomous University of Mexico (Host Glatt-Holtz)

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N-body choreographies are periodic solutions to the N-body equations in which N equal masses chase each other around a fixed closed curve. In my talk I will describe numerical and rigorous continuation and bifurcation techniques in a boundary value setting used to follow Lyapunov families of periodic orbits. These arise from the polygonal system of n bodies in a rotating frame of reference. When the frequency of a Lyapunov orbit and the frequency of the rotating frame have a rational relationship, the orbit is also periodic in the inertial frame. We prove that a dense set of Lyapunov orbits, with frequencies satisfying a Diophantine equation, correspond to choreographies. I will present a sample of the many choreographies that we have determined numerically along the Lyapunov families and bifurcating families. I will also talk about the computer assisted proofs that validate some of theses choreographies. This is joint work with Eusebius Doedel, Carlos García Azpeitia, Jason Mireles-James and Jean-Philippe Lessard.

October 25

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Kayo IdeUniversity of Maryland (Host Glatt-Holtz, Mondaini)

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November 1

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November 8

Microorganism locomotion in viscoelastic fluids

Becca ThomasesUC Davis  (Host:Fauci, Lisa)

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Many microorganisms and cells function in complex (non-Newtonian) fluids, which are mixtures of different materials and exhibit both viscous and elastic stresses. For example, mammalian sperm swim through cervical mucus on their journey through the female reproductive tract, and they must penetrate the viscoelastic gel outside the ovum to fertilize.  A swimming stroke emerges from the coupled interactions between the complex rheology of the surrounding media and the passive and active body dynamics of the swimmer. We use computational models of swimmers in viscoelastic fluids to understand these interactions. I will show results from several recent investigations, and give mechanistic explanations for some different experimental observations. In particular I will discuss how flexible filaments (such as flagella) can store energy from the fluid to obtain speed enhancements from fluid elasticity.

 


November 15

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Clemens HeitzingerTU Vienna (Glatt-Holtz)

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November 22

Thanksgiving



November  30

Special Colloquium

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Mimi KoehlUC Berkeley   (host: Fauci, Lisa)

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December 6

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Mathematics Department, 424 Gibson Hall, New Orleans, LA 70118 504-865-5727 math@math.tulane.edu