lastScrollY=0;
function heartBeat(){ 
	var diffY;
	if (document.documentElement && document.documentElement.scrollTop)
	 diffY = document.documentElement.scrollTop;
	
	percent=.1*(diffY-lastScrollY); 
	
	
	lastScrollY=lastScrollY+percent; 
	//alert(lastScrollY);
}	
window.setInterval("heartBeat()",1);