He returned to Berkeley in 1985 where he is now a full professor .
Afterward he was a National Science Foundation postdoctoral fellow at the Courant Institute , under Peter Lax .
postdoctoral fellow returned to Berkeley in 1985 where postdoctoral fellow is now a full postdoctoral fellow .
Afterward he was a National Science Foundation postdoctoral fellow at the Courant Institute , under Peter Lax .