$(document).ready(function(){
		$('.nav_roll').hover(function(){
			var s = $(this).attr('src');
			var img_pos = s.lastIndexOf('/');
			var img_name = s.substring(img_pos);
			var img_name_new = img_name.replace('_off', '_on');
			s = s.replace(img_name, img_name_new);
			$(this).attr('src', s);
		}, function(){
				var s = $(this).attr('src');
				var img_pos = s.lastIndexOf('/');
				var img_name = s.substring(img_pos);
			
				var img_name_new = img_name.replace('_on', '_off');
				s = s.replace(img_name, img_name_new);

				$(this).attr('src', s);
		}//end mouse out
		);//.nav_roll.hover
		

		var url = window.location.href;
		var page_pos = url.lastIndexOf('/');
		var page_name = url.substring(page_pos+1);
		var s = $('#nav_'+page_name).attr('src');
		var img_pos = s.lastIndexOf('/');
		var img_name = s.substring(img_pos);
		var img_name_new = img_name.replace('_off', '_on');
		s = s.replace(img_name, img_name_new);
		$('#nav_'+page_name).attr('src', s);

	});//document.ready