function slideSwitch(el) {
  var $active = $(el+' DIV.active');
  if ( $active.length == 0 ) $active = $(el+' DIV:last');
  // use this to pull the divs in the order they appear in the markup
  var $next =  $active.next().length ? $active.next()
      : $(el+' DIV:first');
  $active.addClass('last-active');
  $next.css({opacity: 0.0})
      .addClass('active')
      .animate({opacity: 1.0}, 5000, function() {
          $active.removeClass('active last-active');
      });
}