background & aim : the causes of increased rate of cesarean section (c-section) are not completely known. the repeated c-sections are frequently reported in studies conducted in iran. this study aimed to determine the frequency of, and indications for the first time csection (fcs) in zanjan, iran in 2012-2013. methods & materials : a cross-sectional study was conducted and systematic random sam...

A function of boolean arguments is symmetric if its value depends solely on the number of l 's among its arguments. In the first part of this paper we partially characterize those symmetric functions that can be computed by constant-depth polynomial-size sequences of boolean circuits, and discuss the complete characterization. (We treat both uniform and non-uniform sequences of circuits.) Our r...

We obtain sufficient conditions for the finiteness of the moments of the single-server queue busy period in discrete and continuous time. In the cases of power and exponential moments, the conditions found coincide with the known necessary ones. 1. Introduction and notation. Consider a sequence t n n of random vectors with nonnegative coordinates which are i.i.d. in n, but any dependence betwee...