With levels of violence and poverty rising around them, San Francisco middle school students find social and emotional healing -- and a new readiness to learn -- in a bold program of daily meditation.  Back in 1999, when Principal Jim Dierke was getting started at San Francisco's Visitacion Valley Middle School (VVMS) so many fights were breaking out between students that it became known as "the fight school." Police routinely made arrests on campus, and every day, lines of students stretched down the hall...