Iranian authorities on Sunday transferred to hospital a prominent dissident arrested in September as protests swept the country and who is now on hunger strike, his brother said, warning his life is in danger.Hossein Ronaghi, an outspoken freedom of speech campaigner, is one of dozens of prominent rights activists, journalists and lawyers who have been arrested in the crackdown on protests that erupted after the death of Mahsa Amini, who had been arrested by the morality police.