function abrir(URL) {

  var width = 550;
  var height = 450;

  var left = 270;
  var top = 270;

  window.open(URL,'janela', 'width='+width+', height='+height+', top='+top+', left='+left+', scrollbars=no, status=no, toolbar=no, location=no, directories=no, menubar=no, resizable=no, fullscreen=no');

}