By Katie Paul and Sheila Dang (Reuters) – Days after Twitter Inc fired half its staff and new owner Elon Musk tweeted a recommendation to vote for Republican candidates, election experts are anxiously bracing for a surge in online misinformation as Americans head to the polls on Tuesday. Researchers who study election misinformation say threats, offensive language and false rumors of election fraud have been circulating widely ahead of the U.S. midterm elections, which will determine control of Congress for the next two years. Prevalent narratives include false claims that delays in vote count…