// image rollover functions
function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}
function changeImages() {
	if (document.images && (preloadFlag == true)) {
		for (var i=0; i<changeImages.arguments.length; i+=2) {
			document[changeImages.arguments[i]].src = eval(changeImages.arguments[i+1] + ".src");
		}
	}
}
var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		nav_home_over = newImage("images/nav_home_over.gif");
		nav_research_over = newImage("images/nav_research_over.gif");
		nav_training_over = newImage("images/nav_training_over.gif");
		nav_staff_over = newImage("images/nav_staff_over.gif");
		nav_conferences_over = newImage("images/nav_conferences_over.gif");
		nav_materials_over = newImage("images/nav_materials_over.gif");
		nav_subjects_over = newImage("images/nav_subjects_over.gif");

		nav_home_norm = newImage("images/nav_home.gif");
		nav_conferences_norm = newImage("images/nav_conferences.gif");
		nav_materials_norm = newImage("images/nav_materials.gif");
		nav_subjects_norm = newImage("images/nav_subjects.gif");
		nav_training_norm = newImage("images/nav_training.gif");
		nav_research_norm = newImage("images/nav_research.gif");
		nav_staff_norm = newImage("images/nav_staff.gif");
		preloadFlag = true;
	}
	
}
preloadImages();