We will discuss a strong law of large numbers, an annealed CLT, and
the limit law of the ``environment viewed from the particle" for transient
random walks on a strip (product of Z with a finite set). The model was
introduced by Bolthausen and Goldsheid and includes in particular RWRE
with bounded jumps on the line as well as some one-dimensional RWRE with a
memory.
I will discuss geometric flows of G_2 structures on manifolds. These are flows of a 3-form on a 7-manifold with a certain non-degeneracy condition. The form determines a Riemmannian metric in a non-linear way. There is an associated tensor, called the torsion of the G_2 structure, which vanishes if and only if the manifold has G_2 holonomy.
In this talk we will survey the development on the Green's functions of the Boltzmann equations. The talk will include the motivation from the field of hyperbolic conservation laws, the connection between the Boltzmann equation
and the hyperbolic conservation laws, and the particle-like and the wave-like duality in the Boltzmann equation. With all these components one can realize a clear layout of the Green's function of the Boltzmann equation. Finally we will present the application of the Green's function the an initial-boundary value problem in the half space domain.
We will discuss the equations of motion for 3d homogeneous isotropic elastic materials, in the compressible and incompressible case. We will present results on global existence of solutions to the initial value problem, under the assumption of small deformations and with appropriate structural conditions.
In this talk, we shall design and analyze additive and multiplicative multilevel methods on adapted grids obtained by newest vertex bisection. The analysis relies on a novel decomposition of newest vertex bisection which give a bridge to transfer results on multilevel methods from uniform grids to adaptive grids. Based on this space decomposition, we will present a unified approach to the multilevel methods for $H^1$, $H(\rm curl)$, and $H(\rm div)$ systems.
The modern theory of Dynamical Systems is in major part an offspring of celestial mechanics. Poincare proved non-integrability of the three body problem when he discovered the homoclinic picture. Alexeev explained the existence of the oscillatory motions (a planet approaches infinity but always returns to a bounded domain) in Sitnikov model (one of the restricted versions of the three body problem) using methods of hyperbolic dynamics.
We show that the structures related to the most recent results in the smooth dynamical systems (area preserving Henon family and homoclinic bifurcations, persistent tangencies, splitting of separatrices) also appear in the three body problem. In particular, we prove that in many cases the set of oscillatory motions has a full Hausdorff dimension.
numbers greater than or equal to 1 such that 1/p+1/q is less than or equal to 1. The Return Times Theorem proved by Bourgain asserts the following: For each function f in L^{p}(X) there is a universal subset X_0 of X with measure 1, such that for each second dynamical system (Y,Sigma_2,m_2,S), each g in L^{q}(Y) and each x in X_0, the averages 1/N\sum_{n=1}^{N}f(T^nx)g(S^ny) converge for almost every y in Y.
We show how to break the duality in this theorem. More precisely, we prove that the result remains true if p is greater than 1 and q is greater than or equal to 2. We emphasize the strong connections between this result and the Carleson-Hunt theorem on the convergence of the Fourier series. We also prove similar results for the analog of Bourgain's theorem for signed averages, where no positive results were previously known. This is joint work with Michael Lacey, Terence Tao and Christoph Thiele.