LONDON/FRANKFURT (Reuters) - It might not be the kind of attention Bayer wants but persistent takeover talk underlines the attraction of the German group’s new drug pipeline.Shares in the drugs-and-chemicals hybrid spiked higher for the second time in a week on Tuesday, gaining more than 4 percent on renewed speculation that Novartis AG (NOVN.VX: Quote, Profile , Research) was lining up a bid.