[1] Univ Calif Berkeley, Lawrence Berkeley Lab, Dept Math, Berkeley, CA 94720 USA
[2] Univ Calif Berkeley, Lawrence Berkeley Lab, Div Life Sci, Berkeley, CA 94720 USA
[3] Univ Calif Berkeley, Lawrence Berkeley Lab, Joint Grad Grp Bioengn, Berkeley, CA 94720 USA
[4] Univ Calif San Francisco, San Francisco, CA 94143 USA