Portraits of winners of the 2013 Nobel prize for medicine or physiology, James Rothman, Randy Schekman and Thomas Suedhof, are displayed on a screen at the Nobel Assembly in Stockholm

Portraits of winners of the 2013 Nobel prize for medicine or physiology, James Rothman, Randy Schekman and Thomas Suedhof (L-R), are displayed on a screen at the Nobel Assembly at the Karolinska Institute in Stockholm October 7, 2013. REUTERS/Janerik Henriksson/TT News Agency