Today, Joe Simons (a joint advisee of Mike Goodrich and me) passed his thesis defense. Most of my own research with Joe has been on graph drawing, but his dissertation concerned several results on different models of time in dynamic geometric data structures, including the retroactive model (in which updates you make to past versions of the timeline have effects that propagate through other more recent updates), the windowed model (in which you have to aggregate the events that happened within a query window of time into a larger structure), and the local-update model (in which objects can move, but only proportionally to their size). Joe has accepted a position at Google starting this summer.