Operator related function theory and algebraic varieties

Speaker: 

Dr. Greg Knese

Institution: 

UC Irvine

Time: 

Tuesday, November 3, 2009 - 3:00pm

Location: 

RH 306

his talk will be about the interplay between polynomials
whose zero sets interact with the n-torus in C^n (in several natural
ways) and operator related complex function theory (in several natural
settings). Interpolation problems for analytic functions, sums of
(Hermitian) squares formulas, and reproducing kernels all play
important roles. The talk will be relatively non-technical.

Bernstein estimates for weakly coupled fully non-linear elliptic systems

Speaker: 

Prof. Diogo Aguiar Gomes

Institution: 

Mathematics Department of Instituto Superior Tcnico.

Time: 

Tuesday, October 27, 2009 - 3:00pm

Location: 

RH 306

In this talk we discuss Bernstein estimates for weakly fully
non-linear elliptic systems. We are particularly
interested in systems that arise in the stochastic optimal control
problems of hybrid systems. For these a
generalization of Bernstein estimates for first and second derivatives
of classical solutions will be presented.

Variational and PDE Approaches to Texture Modeling and Separation

Speaker: 

Yunho Kim

Institution: 

Visiting Assistant Professor UCI

Time: 

Tuesday, October 13, 2009 - 9:00am

Location: 

RH 340P

This talk will be about a general framework of image processing such as Image denoising, deblurring, segmentation, etc. Variational and also PDE approaches will be considered. Various function spaces will also be mentioned and we will see some advantages and disadvantages of the functions spaces. At the end,
noise - texture characterization or separation techniques will be discussed. Notice that there are no mathematical definitions of noise and texture yet. We will think about this too.

From Mars to Morphogen, a Journey in Applied Mathematics

Speaker: 

Professor Frederick Wan

Institution: 

UCI

Time: 

Wednesday, October 14, 2009 - 5:15pm

Location: 

RH 440R

Professor Fred Wan will describe some highlight of his 50 years long journey in applied mathematics research at four institutions. He will touch on scientific topics such as mechanics, economics, and the biology of Morphogens that guide tissue development.

Random Dirac operators with time reversal symmetry

Speaker: 

Christian Sadel

Institution: 

UCI

Time: 

Thursday, October 15, 2009 - 2:00pm

Location: 

RH 306

We consider random Dirac operators on a strip of width 2L of the form $J\partial+V$ where J is the $2L \times 2L $ symplectic form and V a hermitian matrix-valued random potential satisfying a time reversal symmetry property.
The operator can be analyzed using transfer matrices. The time reversal symmetry forces the transfer matrices to be in the group $SO^*(2L)$. This leads to symmetry and Kramer's degeneracy for the Lyapunov spectrum which forces two Lyapunov exponents to be zero if L is odd. Adopting a criterion
by Goldsheid and Margulis one proves that these are the only vanishing Lyapunov exponents under sufficient randomness. Adopting Kotani theory one obtains a.c. spectrum of multiplicity two on the whole real line. If moreover the random potential includes i.i.d., a.c. distributed matrix Diracpeaks on a lattice in $\RR$, we can adopt the work of Jaksic and Last to prove that the a.c. spectrum is pure. This is a big contrast to the case where L is even and no Lyapunov exponent vanishes for sufficient randomness. There one expects to get pure
point spectrum using similar techniques as in the one dimensional Anderson model. (joint work with H. Schulz-Baldes)

The boundary Haranck principle of the independent sum of Brownian motion and symmetric stable process.

Speaker: 

Professor Panki Kim

Institution: 

Seoul National University

Time: 

Tuesday, November 24, 2009 - 11:00am

Location: 

RH 306

In this talk, we consider the family of pseudo differential operators $\{\Delta+ b \Delta^{\alpha/2}; b\in [0, 1]\}$ that evolves continuously from $\Delta$ to $\Delta + \Delta^{\alpha/2}$. We establish a uniform boundary Harnack principle with explicit boundary decay rate for nonnegative functions which are harmonic with respect to $\Delta +b = \Delta^{\alpha/2}$ (or equivalently, the sum of a Brownian motion and an independent symmetric $\alpha$-stable process with constant multiple $b^{1/\alpha}$) in $C^{1, 1}$ open sets.

Speaker: 

Professor Panki Kim

Institution: 

Seoul National University

Location: 

RH 306

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