Scientific

Cloaking and Transformation Optics

Speaker: 
Gunther Uhlmann
Date: 
Mon, Jul 6, 2009 to Tue, Jul 7, 2009
Location: 
University of New South Wales, Sydney, Australia
Conference: 
1st PRIMA Congress
Abstract: 

We describe recent theoretical and experimental progress on making objects invisible to detection by electromagnetic waves, acoustic waves and quantum waves. Maxwell's equations have transformation laws that allow for design of electromagnetic materials that steer light around a hidden region, returning it to its original path on the far side. Not only would observers be unaware of the contents of the hidden region, they would not even be aware that something was being hidden. The object, which would have no shadow, is said to be cloaked. We recount the recent history of the subject and discuss some of the mathematical and physical issues involved, especially the use of singular transformations.

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What I am Doing in Australia

Speaker: 
Jonathan Borwein
Date: 
Wed, May 18, 2011
Location: 
IRMACS Center, Simon Fraser University
Conference: 
JonFest 2011, Computation & Analytical Mathematics Conference
Abstract: 

Jonathan Borwein talks about his current research and the Priority Research Center for Computer Assisted Research Mathematics and its Applications (CARMA). Professor Borwein is both a Laureate Professor and the Director at CARMA which is located at the University of Newcastle in New South Wales, Australia.

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New geometric and functional analytic ideas arising from problems in symplectic geometry

Speaker: 
Helmut Hofer
Date: 
Mon, Oct 23, 2006 to Tue, Oct 24, 2006
Location: 
PIMS, University of British Columbia
Conference: 
PIMS 10th Anniversary Lectures
Abstract: 

The study of moduli spaces of holomorphic curves in symplectic geometry is the key ingredient for the construction of symplectic invariants. These moduli spaces are suitable compactifications of solution spaces of a first order nonlinear Cauchy-Riemann type operator. The solution spaces are usually not compact due to bubbling-off phenomena and other analytical difficulties.

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Frozen Boundaries and Log Fronts

Speaker: 
Andrei Okounkov
Date: 
Mon, Oct 16, 2006
Location: 
University of British Columbia, Vancouver, Canada
Conference: 
PIMS 10th Anniversary Lectures
Abstract: 

In this talk, based on joint work with Richard Kenyon and Grisha Mikhalkin, Andrei Okounkov discusses a binary operation on plane curves which

  1. generalizes classical duality for plane curves and
  2. arises naturally in probabilistic context,

namely as a facet boundary in certain random surface models.

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On Long-Run Covariance Matrix Estimation with the Truncated Flat Kernel

Author: 
Shinichi Sakata
Date: 
Tue, Jun 3, 2008
Location: 
Simon Fraser University, Burnaby, Canada
Conference: 
PIMS Vancouver Econometrics Workshop
Abstract: 

Despite its large sample efficiency, the truncated flat (TF) kernel estimator of long-run covariance matrices is seldom used, because it lacks the guaranteed positive semidefiniteness and sometimes performs poorly in small samples, compared to other familiar kernel estimators. This paper proposes simple modifications to the TF estimator to enforce the positive definiteness without sacrificing the large sample efficiency and make the estimator more reliable in small samples through better utilization of the bias-variance tradeoff. We study the large sample properties of the modified TF estimators and verify their improved small-sample performances by Monte Carlo simulations.

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