function slideshow() {
  var $alt = jQuery('#diastaple img.top');

  if ($alt.next().length)
    var $neu = $alt.next();
  else
    var $neu = jQuery('#diastaple img:first');

  $alt.addClass('inactive');
  $alt.removeClass('top');
  $neu.css({opacity: 0.0});
  $neu.addClass('top');

  $neu.animate({opacity: 1.0}, 2000, function() {
    $alt.removeClass('inactive');
  });
}


jQuery(document).ready(function() {
   setInterval( "slideshow()", 5000 );
});