function compatibilidad_navegador() {
    //detectar navegador
    var browser_name;
    if ($.browser.msie) browser_name = "IE"; //Internet Explorer
    if ($.browser.mozilla) browser_name = "Firefox"; //Mozilla Firefox
    if ($.browser.webkit && navigator.userAgent.indexOf("Chrome") != -1) browser_name = "Chrome"; //Google Chrome
    if ($.browser.webkit && navigator.userAgent.indexOf("Safari") != -1 && navigator.userAgent.indexOf("Chrome") == -1) browser_name = "Safari"; //Apple Safari
    if ($.browser.opera) browser_name = "Opera"; //Opera
    //document.write(browser_name + " " + parseFloat($.browser.version));

    $(document).ready(
        function() {
            if (browser_name == "IE" && parseFloat($.browser.version) < 8
                || browser_name == "Firefox" && parseFloat($.browser.version) < 1.9){
                $("#actualizacion_navegador").show();
            }
        }
    );
}

function mostrar_ocultar(id) {
    $(id).slideToggle("slow");
}

//Antes declarar una variable timer_interval
function timer_start(interval, function_name) {
    timer_interval = window.setInterval(function_name, interval);
}
function timer_stop(timer_interval){
    window.clearInterval(timer_interval);
}