function showhide (Id) {
    temp=document.getElementById(Id).style.visibility;
    if (temp=="visible")
	document.getElementById(Id).style.visibility="hidden";
	else 
	document.getElementById(Id).style.visibility="visible";
    if (Id=="arxiv") document.getElementById('close').style.visibility=document.getElementById(Id).style.visibility;
}
function footer () {
    temp=document.getElementById('maintext').clientHeight;    
    document.getElementById('copyright').style.top=temp+150;
}