Simultaneous approximation by operators of exponential type

There are many results on the simultaneous approximation by sequences of special positive linear operators. In the year 1978, Ismail and May as well as Volkov independently studied operators of exponential type covering the most classical approximation operators. In this paper we study asymptotic properties of these class of operators. We prove that under certain conditions, asymptotic expansions for sequences of operators belonging to a slightly larger class of operators, can be differentiated term-by-term. This general theorem contains several results which were previously obtained by several authors for concrete operators. One corollary states, that the complete asymptotic expansion for the Bernstein polynomials can be differentiated term-by-term. This implies a well-known result on the Voronovskaja formula obtained by Floater

Wilf's Formula and a Generalization of the Choi-Lee-Srivastava Identities

The identities of Choi, Lee, and Srivastava imply a formula proposed by Wilf. We show that these identities are immediate consequences of the well-known product formulas for the sine function and the cosine function. Moreover, we prove a generalization

Моделирование тлеющего разряда в полом катоде

This article discusses the modeling of low-temperature glow discharge generated plasma with a large area hollow cathode, both in a self-sustained mode and additional electron injection mode. The results of theoretical and numerical investigations of the discharge characteristics agree with experiments

Dephosphorylation of the focal adhesion protein VASP in vitro and in intact human platelets

AbstractThe focal adhesion protein VASP, a possible link between signal transduction pathways and the microfilament system, is phosphorylated by both cAMP- and cGMP-dependent protein kinases in vitro and in intact cells. Here, the analysis of VASP dephosphorylation by the serine/threonine protein phosphatases (PP) PP1, PP2A, PP2B and PP2C in vitro is reported. The phosphatases differed in their selectivity with respect to the dephosphorylation of individual VASP phosphorylation sites. Incubation of human platelets with okadaic acid, a potent inhibitor of PP1 and PP2A, caused the accumulation of phosphorylated VASP indicating that the phosphorylation status of VASP in intact cells is regulated to a major extent by serine/ threonine protein phosphatases. Furthermore, the accumulation of phosphorylated cAMP-dependent protein kinase substrate(s) appears to account for inhibitory effects of okadaic acid on platelet function