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 = changeImages.arguments[i+1];
		}
	}
}

var preloadFlag = false;
function preloadImages() {
	if (document.images) {
		nav_home_over = newImage("images/nav_home_over.gif");
		nav_publications_over = newImage("images/nav_publications_over.gif");
		nav_faq_over = newImage("images/nav_faq_over.gif");
		nav_diagnosis_over = newImage("images/nav_diagnosis_over.gif");
		nav_summerTraining_over = newImage("images/nav_summerTraining_over.gif");
		nav_ncs_over = newImage("images/nav_ncs_over.gif");
		nav_instruments_over = newImage("images/nav_instruments_over.gif");
		nav_scales_over = newImage("images/nav_scales_over.gif");
		preloadFlag = true;
	}
}