Friends with poor memory?

Four previous colleagues of mine are now leaving unanswered email I have sent to them. They are:

George Blumenthal, formerly my thesis advisor at UC Santa Cruz and now chancellor of the university.

Bill Keel, former astronomy graduate student at UC Santa Cruz and now professor of astronomy at the University of Alabama.

Peter Beltemacchi, professor of architecture at the Illinois Institute of Technology.

Peter Land, professor of architecture at the Illinois Institute of Technology.