LONDON (REUTERS).- Chinese dissident artist Ai Weiwei, whose 81-day detention earlier this year caused an international outcry, has been named the art world’s most powerful figure in a new ranking. Contemporary art magazine ArtReview published its 10th annual “Power 100” list on Thursday, coinciding with the opening of the Frieze Art Fair in London which attracts many of the world’s top galleries and collectors. Ai, famous for his “Bird’s Nest” Olympic Stadium in Beijing and a recent installation at London’s Tate Modern gallery comprising millions of replica porcelain sunflower seeds, was 13th in the ranking last year. Unchanged in second place was London’s Serpentine Gallery co-director Hans Ulrich Obrist, joined by his colleague Julia Peyton-Jones this time around. They are followed by New York’s Museum of Modern Art director Glenn D. Lowry, and, in fourth down from first last year, U.S. gallery owner Larry Gagosia