Matthias Pintscher is the guest conductor this weekend with the Pittsburgh Symphony Orchestra.  He'll conduct Ravel's "Mother Goose" and "Alborada del gracioso," as well as Debussy's "La Mer."   Alexi Kenney will play the Bartok Violin Concerto No. 2.  Matthias talks to WQED-FM's Jim Cunningham about the concert, his recordings and composing and more.