Central subsets of a discrete semigroup S have very strong combinatorial properties which are a consequence of the Central Sets Theorem. Call a set a C-set if it satisfies the conclusion of the Central Sets Theorem. We obtain here a reasonably simple characterization of C-sets in an arbitrary discrete semigroup.

We present analytical calculation of the rst seven moments of the heavy quark vacuum polarization function in the three-loop order. The obtained results are compared against the asymptotic formulas following from the threshold singulari-ties. We also discuss the dependence of the moments within the BLM procedure.

In the paper we introduce the notion of Bi Unique Range Sets for derivatives of meromorphic functions and with the aid of the same we improve all previous results regarding derivatives of set sharing.

Introduction. The two sections of this note are independent, but they are related by the fact that both use the results of [5 ] to obtain information on the properties of weakly compact sets in Banach spaces. In the first section we prove some results on a class of compact sets which is believed to include all weakly compact subsets of Banach spaces. We are interested in the properties of the n...

background: forecasting of air pollutants has become a popular topic of environmental research today. for this purpose, the artificial neural network (aan) technique is widely used as a reliable method for forecasting air pollutants in urban areas. on the other hand, the evolutionary polynomial regression (epr) model has recently been used as a forecasting tool in some environmental issues. in ...

following our interest in reaching for a molded rubber article with possible detergent contact applications, durable silver nanopowder (agnp) is synthesized by arc discharge, then mixed with varying ratios of ethylene propylene rubber (epr), affording novel agnp@epr nanocomposites. x-ray diffraction (xrd) patterns of agnp as well as agnp@epr show no trace of impurity, while scanning electron mi...

Nitrogenase MoFe protein (Kp1) from the mutant strain pHK17 or Klebsiella pneumoniae has been purified to give three catalytically active fractions. In this mutant, each of the two bridging cysteine ligands to the P-clusters, alpha-Cys-89 and beta-Cys-94, has been replaced by a non-coordinating residue, alanine. SDS/PAGE and earlier native gels showed that the three fractions retained the norma...

Article history: Received 8 April 2008 Received in revised form 14 May 2008 Accepted 27 June 2008 Available online 5 July 2008 PACS: 61.50.-f 71.15.Mb 71.27.+a