I was a schoolmate of David in Niagara Falls, N.Y.  He was a great friend and inspired me to take an interest in amateur radio, having often visited his impressive basement radio station.  I believe his call letters were WV2SEU.  So sorry to hear of his passing.  He was an extraordinary individual in so many ways. I will never forget him. My sincere condolences to his family and friends.  

I worked part-time with Dave at Alceon between 1989 and 1993, mostly on risk assessments of hazardous waste sites.  Dave had great energy and a seemingly bottomless fund of scientific knowledge.  He was always in good spirits, and was courteous, thoughtful, and open-minded.  To borrow a phrase of my father's, Dave was a gentleman and a scholar—and I know he will be remembered as such.

Dave was a kind and intellectually curious person.  He was gracious, decent, and generous.  His devotion to MIT was enormous, and I know that many students and others there benefitted greatly from his efforts, large and small.  His contributions to the field of health risk assessment -- especially methods for assessing variabilities and uncertainties -- remain important.  I will miss him.

David and I knew each other from 7th grade on. He was one of the most brilliant people I have ever known. In fact, he was voted most likely to succeed in our high school graduating class. He had an insatiable appetite for new knowledge; technology; and I left every conversation enriched beyond words. I will miss our times together and his kind and caring ways. Our sympathies to his family.

Dave was one of the nicest people I’ve met.  He was open and giving - something rare.  Yes, brilliant.  Creative and passionate about issues of concern to humanity.  I am grateful to have known him.  Safe passage, my friend.