In August of 1852 Dr. Walter Channing, professor of obstetrics and medical jurisprudence at Harvard Medical School, was about to finish an extensive tour of Europe, having left Boston early in May of that year. He was sixtysix at the time, and almost a half century had passed since his previous trip to that continent where as a medical student he studied in Edinburgh and London. The trip had ta...

The Deligne-Simpson problem is formulated like this: give necessary and sufficient conditions for the choice of the conjugacy classes Cj ⊂ SL(n,C) or cj ⊂ sl(n,C) so that there exist irreducible (p + 1)-tuples of matrices Mj ∈ Cj or Aj ∈ cj satisfying the equality M1 . . .Mp+1 = I or A1 + . . .+Ap+1 = 0. We solve the problem for generic eigenvalues with the exception of the case of matrices Mj ...

In the current issue of the Journal, Tu et al. (1) show convincingly that if there is no correlation between birth weight and blood pressure but both are positively correlated with current weight (which they are), then adjustment for current weight can induce a negative correlation between birth weight and blood pressure. This demonstration may be important in stimulating epidemiologists to ret...