In this talk, I review the mathematical results of the
dynamcis of Bose-Einstein condensate (BEC) and present
some efficient and stable numerical methods to compute ground states
and dynamics of BEC. As preparatory steps,
we take the 3D Gross-Pitaevskii equation (GPE) with an angular
momentum rotation, scale it to obtain a four-parameter model
and show how to reduce it to 2D GPE in certain limiting regimes.
Then we study numerically and asymptotically the
ground states, excited states and quantized vortex
states as well as their energy and chemical potential diagram
in rotating BEC. Some very interesting numerical results are
observed. Finally, we study numerically stability and interaction
of quantized vortices in rotating BEC. Some interesting interaction
patterns will be reported.
Smoluchowski's equation is used to describe the coagulation-fragmentation
process macroscopically. Microscopically clusters of various sizes coalesce to
form larger clusters and fragment into smaller clusters. I formulate a conjecture about the nature of the fluctuations of the microscopic
clusters about the solutions to the Smoluchowski's equation. I also sketch the proof of the conjecture when the model is in equilibrium.
Abstract: (Thanks to work of Abel Klein and others) it is understood how
to represent the quantum Ising model in terms of a certain classical model
of stochastic geometry called the `continuum random-cluster model'. In the
regime of large external field, this geometrical model is subcritical. By
developing bounds for its `ratio weak' mixing rate, one obtains estimates
involving the reduced density matrix of the quantum Ising model. The
implications of these estimates for entanglement do not appear to be best
possible, but they are at least robust for disordered systems. [Joint work
with Tobias Osborne and Petra Scudo.]
I will introduce a recent conjecture of Hayes concerning the value at s=0 of the
equivariant Artin L-function associated with an Abelian extension K/k of number fields. It
proposes a relationship between certain unramified Kummer extensions of K and the
denominators of the coefficients of this L-function value. The conjecture can be viewed as a
new generalization of the classical analytic class number formula.
The T-adic L-function is a unversal L-function which
interpolates classical L-functions of all p-power order
exponential sums associated to a polynomial f(x) defined
over a finite field. We study its T-adic analytic properties
(analytic continuation and its T-adic Newton polygon).
The T-adic Newton polygon provides a uniform improvement
to previous results on p-adic Newton polygon of exponential sums
in the non-ordinary case. This is joint work with Chunlei Liu.
The index theorem for an elliptic operator gives an integrality theorem; a characteristic integral over the manifold is an integer because it is the index of the operator. I will review some geometric examples: the Dirac operator on a spin manifold, the spin_C Dirac operator, and their analogues for complex manifolds.
When the manifold has no spin_C structure, these operators do not exist. Nevertheless one can define a 'projective' Dirac operator which has an analytic index with values in the rationals. This fractional analytic index can also be expressed as a characteristic integral. I'll describe a possible application to string theory. [Joint work with V. Mathai and R.B. Melrose, J. Diff Geom 74 no 2 (2006) math.DG/0206002]
I'll begin with the Battelle Rencontre "Lectures in Mathematics and Physics" (Seattle, 1967) and end with S-duality as reflected in Mirror Symmetry and in the Electric-Magnetic Duality connection with the Geometric Langlands Program. In between will be a guided tour of special moments in the interaction of mathematicians and high energy theorists: gauge theory and fibre bundles, instantons and index theory, string theory and Calabi-Yau manifolds.
We have study the coupled ocean-ice dynamics in the marginal ice zone (MIZ) in the Bering Sea. First, sea ice motion and deformation have been analyzed using the high resolution synthetic aperture radar (SAR) images. Segmentation techniques and statistical methods have been used to derive ice motion and deformation maps. These techniques involve a dynamic local thresholding (DLT), which allows separation of sea ice into different classes of thickness and type. We observed two ice motion characteristics with one consisting of a translation and a rotation at scale larger than about 10km/day and the other being ice field deformations at spatial scale less than about 5km. The results were compared with low-resolution values derived from Advanced Microwave Scanning Radiometer for EOS (AMSR-E) data for consistency. In addition, we implemented a two-dimensional coupled ice-ocean model (with wave effects incorporated) and made a direct comparison between the model and remote sensing results. Preliminary results on the effects of waves on ice cover were also obtained.
We discuss some recent developments in the problem of Khler metrics of constant scalar curvature and stability in geometric invariant theory. In particular, we discuss various notions of stability, both finite and infinite-dimensional, and various analytic methods for the problem. These include estimates for energy functionals, density of states and Tian-Yau-Zelditch and Lu asymptotic expansions, geometric heat flows, and both a priori estimates and pluripotential theory for the complex Monge-Ampre equation.