$(window).ready(function () {
    $('#slides').cycle({ 
        speed:  'fast', 
        timeout: 5000, 
        pager:  '#nav_slides',
        fx: 'fade',
        before: function(curr, next, options, flag) {
            $("#slides_descricao").hide()
            $("#slides_descricao").text("")
        },
        after: function(curr, next, options, flag) {
            $("#slides_descricao").text($(next).children('img').attr("alt"));
            $("#slides_descricao").slideDown(200);
        }
    });
});