An application of von Neumann algebras to Gabor frames

Speaker: 

Bernie Russo

Institution: 

University of California, Irvine

Time: 

Friday, October 29, 2004 - 2:00pm

Location: 

MSTB 256

A sketch of the proof of Daubechies, Landau and Landau (1995) using elementary von Neumann algebra theory of Rieffel's (1981) incompleteness theorem: If ab>1, then there does not exist a square integrable function g whose Gabor lattice G(g,a,b) is dense in L^2.

Weak Wave Turbulence and its Challengers

Speaker: 

Dr. Laura Biven

Institution: 

Max-Planck-Institut fur Physik Komplexer Systeme

Time: 

Monday, November 8, 2004 - 4:00pm

Location: 

MSTB 122

I will begin my talk with a brief overview of WWT during which I aim to give an intuitive picture of the phenomenon using the example of surface water waves. This example will be revisited throughout the talk. Next I will try to give a welcoming (although selective) introduction to the calculations of WWT. Equipped with the results of these calculations, I will discuss the relationship between WWT, power-law spectra (both Kolmogorov-Zakharov and MMT) and intermittency. The challengers to WWT are highly nonlinear events, breakdown and the alternative symmetries of the governing equation. I will make some remarks which point out the interconnectedness of these phenomena and, simultaneously, the goals of my research interests.

A Tale of Two Topologies: Canonical Forms for Ion Channel Data Analysis

Speaker: 

Dr. John Pearson

Institution: 

Los Alamos National Laboratory

Time: 

Tuesday, November 2, 2004 - 1:00pm

Location: 

MSTB 254

In this talk I will introduce the manifest interconductance rank (MIR) form and contrast it to another long-known canonical form used in the
data-driven identification of ion channel gating kinetics: the uncoupled model (UCM). (The UCM has every open state connected to every closed state and vice versa). MIR form has significantly fewer parameters and provides more insight into gating kinetics than the uncoupled model. Beyond the new canonical form the principle results to be presented are
(1)All topologies with interconductance rank=1 and with the same number of open and closed states result in identical steady-state statistics
(2)detailed balance is preserved under transformation to either UCM or MIR forms and
(3) a general detailed balance preserving transformation. These results should facilitate maximum likelihood methods for finding models that best fit a given data set.

Speaker: 

Time: 

Saturday, November 20, 2004 - 10:00am

Location: 

MSTB 118

Southern California Number Theory Day

Aspects of Total Variation Regularized L1 Function

Speaker: 

Professor Tony Chan

Institution: 

UCLA

Time: 

Thursday, April 7, 2005 - 4:00pm

Location: 

MSTB 254

The total variation based image denoising model of Rudin, Osher,
and Fatemi
has been generalized and modified in many ways in the literature; one of
these modifications is to use the L1 norm as the fidelity term. We study the
interesting consequences of this modification, especially from the point of
view of geometric properties of its solutions. It turns out to have
interesting
new implications for data driven scale selection and multiscale image
decomposition.

(joint work with Selim Esedgolu).

An application of Time-frequency analysis to von Neumann algebras

Speaker: 

Bernie Russo

Institution: 

UCI

Time: 

Friday, November 5, 2004 - 2:00pm

Location: 

MSTB 256

Last week we discussed the proof (due to Daubechies, Landau, and Landau 1995) of Rieffel's incompleteness theorem using elementary von Neumann algebra theory but avoiding Rieffel's intractable coupling constant argument. This week we discuss the proof, (from the same paper and based on time-frequency analysis ideas) of the existence of the coupling constant for the von Neumann algebra generated by the basic time-frequency operators. The significance of the coupling constant will be mentioned.

Low weight degree four Galois representations and Siegel modular forms

Speaker: 

Jacques Tilouine

Institution: 

Paris 13 and Caltech

Time: 

Saturday, November 20, 2004 - 2:30pm

Location: 

MSTB 118

We show that certain abelian surfaces come from p-adic Siegel cusp forms (in the sense that they have the same p-adic Galois representation). This relates to the question: unless it is isogenous to a product of elliptic curves, does an abelian surface come from a Siegel cusp form?

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