function tablesorter_handler(event)
{
    var elem_id = event.target.id;
    elem_sort = ($("#result_table #" + elem_id).attr("sort") == "asc") ? "desc" : "asc";
    $("#result_table #" + elem_id).attr("sort", elem_sort);
    $("input[id$='_sort_field']").val(elem_id+":"+elem_sort);
    return false;
}