function esValidoEmail(valor) {
                if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(valor)){
                        return (true)
                } else {
                        return (false);
                }

         }

        function popup(url, name, ancho, alto){
                var caracteristicas;
                caracteristicas="screenX=50,screenY=50,location=0,resizable=0,status=0,titlebar=1,directories=0,toolbar=0,menubar=0,scrollbars=1,status=0";
                ancho = ancho+50;
                alto=alto+70;

                if(ancho>0) caract_ancho=",WIDTH="+ancho;
                else  caract_ancho="WIDTH=300";

                if(alto>0) caract_alto=",HEIGHT="+alto;
                else  caract_alto= ",HEIGHT=350";

                caracteristicas= caracteristicas + caract_ancho+caract_alto;

                newWin=window.open(url, name, caracteristicas);
                var windowX = (screen.width/2)-(ancho/2);
                var windowY = (screen.height/2)-(alto/2);

                newWin.moveTo(windowX,windowY)

                newWin.focus();
                onscreen=true;
        }