1. University of Ioannina School of Health Sciences, Ioannina, Greece (A.T., F.B.K.)
2. Stanford University, Stanford, California (S.N.G., J.P.I.)
3. Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts (D.A.Z.)
4. London School of Economics and Political Science, London, United Kingdom (D.F.)