improvements in the two-step synthesis of 1,1,1,3,3,3-hexafluoro-2- (fluoromehoxy)propane (sevoflurane) that result in the product cost reduction, safety level enhancement and positive environmental impacts are described. this process consists of chloromethylation reaction of 1,1,1,3,3,3-hexafluoro-2-propanol (hfip) followed by a halogen-exchange fluorination. this is the first synthesis of sev...

This paper examines the asymptotic and …nite-sample properties of tests of equal forecast accuracy when the models being compared are overlapping in the sense of Vuong (1989). Two models are overlapping when the true model contains just a subset of variables common to the larger sets of variables included in the competing forecasting models. We consider an out-of-sample version of the two-step ...

influence of media messages History and Orientation The two-step flow of communication hypothesis was first introduced by Paul Lazarsfeld, Bernard Berelson, and Hazel Gaudet in The People's Choice, a 1944 study focused on the process of decision-making during a Presidential election campaign. These researchers expected to find empirical support for the direct influence of media messages on voti...