function rollover(str) {

	obj=document.getElementById(str+"nav");
	obj.src="img/"+str+"_over.gif";

}


function rollout(str) {

	obj=document.getElementById(str+"nav");
	obj.src="img/"+str+".gif";

}

function newImage(arg) {
	if (document.images) {
		rslt = new Image();
		rslt.src = arg;
		return rslt;
	}
}

function preloadImages() {
	if (document.images) {
		stanford_over = newImage("img/stanford_over.gif");
		english_over = newImage("img/english_over.gif");
		biography_over = newImage("img/biography_over.gif");
		cv_over = newImage("img/cv_over.gif");
		books_over = newImage("img/books_over.gif");
		teaching_over = newImage("img/teaching_over.gif");
		extra_over = newImage("img/extra_over.gif");
	}
}