function showAvailability(uri) {
 	var x = (screen.availWidth - 290)/2;
    var y = (screen.availHeight - 225)/2;
    var w = window.open(uri, 'VERFUEGBARKEITEN', 'width=290,height=240,top=' + y + ',left=' + x + ',scrollbars=no');
    w.focus();
   return false;
}