Free speech is essential to education, especially to a liberal education, which encourages the search for truths in art and science. If expression is restricted, the range of inquiry is also curtailed... The beneficiaries of a free society have a duty to pursue the truth and to protect the freedom of expression that makes possible the search for a new enlightenment.
by Norman Dorsen

My talks at IMPA (streaming videos)

Geometry of Gelfand-Cetlin integrable system (Conservative dynamics and symplectic geometry  2009):

http://strato.impa.br/videos/workshop_geometry/geometry_070809_03.avi

Dynamics on Poisson manifolds (Poisson 2010):

http://strato.impa.br/videos/poisson/poisson_26072010_nguyen.flv

(now that I listened to my own talk at IMPA, I found that my English was really horrible !)

For all video lectures recorded by IMPA:

http://video.impa.br