function changeOpacity(){
	var blink_tags = $$('strong.blink');
	blink_tags.each(function(item) {
	    var opacity = item.getStyle('opacity');
	    if(opacity==1) {
    	    Element.setOpacity(item, 0);
    	}
    	else {
    	    Element.setOpacity(item, 1);
	    }
	});
	setTimeout("changeOpacity()", 500);
}