NEW HAVEN, Conn. (AP) — Yale University has said its formal goodbyes to Annie Le , the 24-year-old graduate student found strangled last month behind a wall in a medical school building’s laboratory.Classmates, professors and others gathered Monday at the university’s historic Battell Chapel for a memorial service that was open only to members of the Yale community.University President Richard Levin remembered Le as a model student, a child of immigrants who was at the same time bright, caring, loving and spontaneous.Le, originally from Placerville, Calif., worked on a team that experimented on mice as part of research into enzymes that could have implications for treatment of cancer, diabetes and muscular dystrophy. She disappeared on Sept. 8 and her body was found five days later.