Sad days

It's been a rough few weeks at work: first, a graduate student died rather suddenly (he'd had an operation on his knee, and got a clot which travelled to his lungs): next a (young-ish) colleague had a stroke, from which we are all hoping he will recover: then this afternoon, I heard that an undergraduate with whom I had worked quite closely over the past few years --- he was now a graduate student elsewhere --- was cycling to work this morning and was hit by a truck.
I'm not a superstitious type, but it would be nice if this stretch of bad happenings only came in threes.

MK: in memoriam,
N.