2236-3459 2236-3459 S2236-34592012000200125 10.1590/S2236-34592012000200007 Brazil Brazil 00 09 2012 00 09 2012 16 38 125 147

31 2 2 124-38 26 1 1 99-117 22 37-50 1 2 2 64-89