We analyze the puzzling behavior of the volatility of individual stock returns over the past few decades. The literature has provided many different explanations to the trend in volatility and this paper tests the viability of the different explanations. Virtually all current theoretical arguments that are provided for the trend in the average level of volatility over time lend themselves to ex...

purpose: this research has done in order to study ranganathan's reference theory and its durability throughout the time . methodology: the method of this research was the review method to study and investigate ranganathan's works and the related literature that used his view and theory in the reference and the reference services. findings: the results of the study is about introducing ranganath...

objective(s):therapies with high levels of oxygen are commonly used in the management of critical care. however, prolonged exposure to hyperoxia can cause acute lung injury. although oxidative stress and inflammation are purported to play an important role in the pathogenesis of acute lung injury, the exact mechanisms are still less known in the hyperoxic acute lung injury (hali).   materials a...