function next_page()
	{
	var next_no = page_no + 1;
	if (next_no == 12)
		{
		next_no = 1;
		}
	location = next_no + ".html";
	}
function prev_page()
	{
	var prev_no = page_no - 1;
	if (prev_no == 0)
		{
		prev_no = 11;
		}
	location = prev_no + ".html";
	}
function mailafriendurl()
	{
	var url = "http://www.nature.com/news/svc/mailform?file=/news/specials/chimp/";
	if (page_no)
		{
		url = url + page_no + ".html";
		}
	window.open(url,'mailafriend','');
	}
function resize()
	{
	if (window.innerHeight)
		{
		window.innerHeight=500;
		window.innerWidth=700;
		}
	}