Berlin renamed a stretch of the Spree River in honor of a gay-rights activist persecuted by the Nazis in the 1930s as the city's biggest hospital opened an exhibition devoted to the sex researcher. A stretch of the Spree River in central Berlin was named after gay-rights activist and sexual researcher Magnus Hirschfeld in a dedication ceremony on Tuesday, May 6.   On the same day 75 years ago, the Nazis plundered his offices and later burned hundreds of his books.   Hirschfeld had founded the world's first institute dedicated to fighting discrimination against homosexuals. He went into exile in ...