Motivated by applications in microwave engineering and diffusion tensor imaging, we study the problem of deconvolution density estimation on the space of positive definite symmetric matrices. We develop a nonparametric estimator for the density function of a random sample of positive definite matrices. Our estimator is based on the Helgason-Fourier transform and its inversion, the natural tools...

A unified scheme for quantum measurement processes is formulated on the basis of Micro-Macro duality as a mathematical expression of the general idea of quantum-classical correspondence. In this formulation, we can naturally accommodate the amplification processes necessary for magnifying quantum state changes at the microscopic end of the probe system into the macroscopically visible motion of...

1. Historical origins of Lie group theory. Nowadays when Lie groups enter in a profound way into so many areas of mathematics, their historical origin is of considerable general interest. The connection between Lie groups and differential equations is not very pronounced in the modern theory of Lie groups, so in this introduction we attempt to describe some of the foundational work of S. Lie, W...

We define the forward and backward radiation fields on an asymptotically hyperbolic manifold and show that they give unitary translation representations of the wave group, and as such can be used to define a scattering matrix. We show that this scattering matrix is equivalent to the one defined by stationary methods. Furthermore, we prove a support theorem for the radiation fields which general...

Diffusion tensor imaging can be studied as a deconvolution density estimation problem on the space of positive definite symmetric matrices. We develop a nonparametric estimator for the common density function of a random sample of positive definite matrices. Our estimator is based on the Helgason-Fourier transform and its inversion, the natural tools for analysis of compositions of random posit...

A notion of band limited functions is considered in the case of the hyperbolic plane in its Poincare upper half-plane H realization. The concept of band-limitedness is based on the existence of the Helgason-Fourier transform on H. An iterative algorithm is presented, which allows to reconstruct bandlimited functions from some countable sets of their values. It is shown that for sufficiently den...

The main purpose of this paper is to establish the existence, nonexistence and symmetry nontrivial solutions higher order Brezis-Nirenberg problems associated with GJMS operators Pk on bounded domains in hyperbolic space Hn as well entire Hn. Among techniques different from problem Euclidean spaces, one our novelties study existence use crucially Helgason-Fourier analysis spaces Hardy-Sobolev-M...

given a mapping $f:xto x$ we naturally associate to it a monotonic map $gg_f:exp xto exp x$ from the power set of $x$ into itself, thus inducing a generalized topology on $x$. in this paper we investigate some properties of generalized topologies which are defined by such a procedure.