Many materials problems require the accuracy of atomistic modeling in small regions, such as the neighborhood of a crack tip. However, these localized defects typically interact through long ranged elastic fields with a much larger region that cannot be computed atomistically. Many methods have recently been proposed to compute solutions to these multiscale problems by coupling atomistic models near a localized defect with continuum models where the deformation is nearly uniform. During the past several years, we have given a theoretical structure to the description and formulation of atomistic-to-continuum coupling that has clarified the relation between the various methods and the sources of error. Our theoretical analysis and benchmark simulations have guided the development of optimally accurate and efficient coupling methods.

There is a good deal of resemblence of CR geometry in dimension three with conformal geometry
in dimension four. Exploiting this resemblence is quite fruitful. For instance, the presence of
several conformally covariant operators in both geometries allows us to formulate correct
conditions for the embedding problem as well as the CR Yamabe problem. There is also
large difference in the presence of pluriharmonic functions. I will also describe a new
operator which gives control of the pluriharmonics and allows a formulation of a
sphere theorem in this geometry.

 
This talk will discuss the problem of finding effective laws that the govern the overall evolution of free boundaries propagating in a heterogeneous media.  This is motivated by a number of phenomena in mechanics and materials physics including phase boundaries, peeling of adhesive tape, dislocations, fracture and wetting fronts.   While there is a rigorous mathematical theory of homogenization in the context of properties that are characterized by a variational principle, much remains unknown about equations that describe evolutionary processes.   The talk will discuss the mathematical issues, difficulties and results, and illustrate the implication on materials through selected examples.  The talk will conclude with current work on free discontinuity problems.

What could be simpler than to study sums and products of integers? Well maybe it is not so simple since there is a major unsolved problem: for arbitrarily large numbers N, can there be sets of N positive integers where both the number of pairwise sums and pairwise product is less than N^{3/2}?

No one knows. This talk is directed at another problem concerning sums and products, namely how dense can a set of positive integers be if it contains none of its pairwise sums and products? For example, take the numbers that are 2 or 3 more than a multiple of 5, a set with density 2/5. Can you do better?

I will review briefly some recent developments in financial mathematics research, put them in a historical context, and then discuss the modeling and analysis of systemic risk phenomena.