Based on social network perspective, we developed a model about the knowledge sharing of communities of practice (CoPs), analyzed the knowledge sharing of CoPs from the view of the network density, network centrality, network structure. And we found out that only the above indexes are kept in appropriately level can stimulate the knowledge sharing in CoPs. The strong ties contribute to the tran...

A secure index is a data structure that allows a querier with a " trapdoor " for a word x to test in O(1) time only if the index contains x; The index reveals no information about its contents without valid trapdoors, and trapdoors can only be generated with a secret key. Secure indexes are a natural extension of the problem of constructing data structures with privacy guarantees such as those ...

background: to evaluate the situation in a district demographic and health indexes are of great  importance. the aim of this article is to analyze some demographic and health indexes in chadegan district during 2004-2009. methods: this was a descriptive study and the target population was the population of chadegan district from 2004-2009. data collection was done according to registered data i...