2236-3459 2236-3459 S2236-34592012000200149 10.1590/S2236-34592012000200008 00 09 2012 00 09 2012 16 38 149 166

103 103 136-49 16 1 1 91-102 34 22009 22009 97-118 52 52 55-73 6 6 68-96