* Wall St shrugs off encouraging jobless report* Fed minutes show worry over global economy, strong dollar* Treasuries yields at recent record lows* Brent oil under $91 a barrel(Adds New York open, comments, changes dateline; previous LONDON)By Michael ConnorNEW YORK, Oct 9 (Reuters) - Concerns about lackluster growth in world economies sent Wall Street and other world stock markets lower on Thurs