A sign pattern is a matrix with entries in {+, −, 0}. A full sign pattern has no zero entries. The refined inertia of a matrix pattern is defined and techniques are developed for constructing potentially nilpotent full sign patterns. Such patterns are spectrally arbitrary. These techniques can also be used to construct potentially nilpotent sign patterns that are not full, as well as potentiall...

The relationship between the Jordan forms of the matrix products AB and BA for some given A and B was first described by Harley Flanders in 1951. Their non-zero eigenvalues and non-singular Jordan structures are the same, but their singular Jordan block sizes can differ by 1. We present an elementary proof that owes its simplicity to a novel use of the Weyr characteristic.

A perturbation result, due to R. Rado and presented by H. Perfect in 1955, shows how to modify r eigenvalues of a matrix of order n, r ≤ n, via a perturbation of rank r, without changing any of the n − r remaining eigenvalues. This result extended a previous one, due to Brauer, on perturbations of rank r = 1. Both results have been exploited in connection with the nonnegative inverse eigenvalue...

Ca(+) signaling plays a crucial role in control of cell cycle progression, but the understanding of the dynamics of Ca(2+) influx and release of Ca(2+) from intracellular stores during the cell cycle is far from complete. The aim of the present study was to investigate the role of the free extracellular Ca(2+) concentration ([Ca(2+)](o)) in cell proliferation, the pattern of changes in the free...

PURPOSE Recanalization of chronic total occlusions (CTOs) of the femoropopliteal arteries depends on a successful lesion crossing with the guide wire. The aim of this retrospective study was to evaluate the safety, feasibility, and the primary results of retrograde recanalization of CTOs with balloon-assisted excimer-laser atherectomy (ELA) via a transpopliteal approach after failed antegrade a...

We have recently shown that the adenovirus EIA gene products block interferon-a-induced signal transduction and transcription factor NF-cB-mediated gene induction. Here we report that the same responses are also blocked in undifferentiated F9 teratocarcinoma cells. The block was removed upon cellular differentiation and regained upon the introduction of viral EIA into the differentiated cells. ...