We show that the approximation numbers of a compact composition operator on the weighted Bergman spaces Bα of the unit disk can tend to 0 arbitrarily slowly, but that they never tend quickly to 0: they grow at least exponentially, and this speed of convergence is only obtained for symbols which do not approach the unit circle. We also give an upper bounds and explicit an example. Mathematics Su...

We show that an invertible bilateral weighted shift is strongly structurally stable if and only it has the shadowing property. also exhibit a K{o}the sequence space supporting frequently hypercyclic shift, but no chaotic shifts.

In this paper we consider the problem of finding norms of certain matrix operators on sequence space bvp . In fact, we consider these problems for weighted mean, and generalized Cesaro matrices on sequence space bvp . Mathematics subject classification (2010): 26D15, 47A30, 40G05, 47D37, 46A45, 54D55.

This paper is concerned with the problem of finding bounds for the norm of lower triangular matrix operators from [Formula: see text] into [Formula: see text], where [Formula: see text] is the Cesàro weighted sequence space and [Formula: see text] is a non-negative sequence. Also this problem is considered for lower triangular matrix operators from [Formula: see text] into [Formula: see text], ...

Background: To assess MRI in diagnosing endometriotic lesions, emphasizing T2*weighted imaging efficacy. Materials and Methods: This prospective study of 48 females (22-38 years, average 29.6) clinically suspected of endometriosis from September 2009 to April 2012. MRI was performed with a 1.5 T imager (Siemens) with a body array coil. T1, T2 and T2* weighted (2D-FLASH) sequences were obtained ...