Leslie Bider has been elected to the board of OSI Systems Inc., a Hawthorne, Calif., provider of specialized electronics for applications in the health-care and security industries. Bider is a parner with Elevation Partners, a Menlo Park, Calif.- and New York-based private equity firm and is the founder and manager of Bider & Montgomery, a Los Angeles accounting firm. Previously, he was CEO of Warner Chappell Music Inc. and chief financial officer and chief operating officer at Warner Bros. Music.