http://www.cell.com/current-biology/abstract/S0960-9822%2815%2900542-4?mobileUi=0 For those who never saw the snap (decreased luminosity on the left, increased on the right, as originally posted in the middle) http://i.f1g.fr/media/figaro/805x453_crop/2015/05/15/XVMa9171b1a-fb0a-11e4-8c21-c4edfd7ed674.jpg Bien cordialement Philippe