function rotateHeader(){
	
var headerList = new Array()
headerList[0] = "http://www.sas.upenn.edu/home/assets/img/pages/header_photo1.jpg"
headerList[1] = "http://www.sas.upenn.edu/home/assets/img/pages/header_photo2.jpg" 
headerList[2] = "http://www.sas.upenn.edu/home/assets/img/pages/header_photo3.jpg"
headerList[3] = "http://www.sas.upenn.edu/home/assets/img/pages/header_photo4.jpg"	
	
var headerImage = headerList[(Math.round(Math.random()*(headerList.length-1)))];
document.getElementById('topimage').style.backgroundImage = "url("+headerImage+")";

}


function alumniHeader(){
	
var alumniList = new Array()
alumniList[0] = "http://www.sas.upenn.edu/home/assets/img/pages/alumni_header1.jpg"
alumniList[1] = "http://www.sas.upenn.edu/home/assets/img/pages/alumni_header2.jpg" 
alumniList[2] = "http://www.sas.upenn.edu/home/assets/img/pages/alumni_header3.jpg"
alumniList[3] = "http://www.sas.upenn.edu/home/assets/img/pages/alumni_header4.jpg"	
	
var alumniImage = alumniList[(Math.round(Math.random()*(alumniList.length-1)))];
document.getElementById('topimage').style.backgroundImage = "url("+alumniImage+")";

}	

function globalHeader(){
	
var globalList = new Array()
globalList[0] = "http://www.sas.upenn.edu/home/assets/img/pages/global_hum_header1.jpg"
globalList[1] = "http://www.sas.upenn.edu/home/assets/img/pages/global_hum_header2.jpg" 
globalList[2] = "http://www.sas.upenn.edu/home/assets/img/pages/global_hum_header3.jpg"
	
var globalImage = globalList[(Math.round(Math.random()*(globalList.length-1)))];
document.getElementById('topimage').style.backgroundImage = "url("+globalImage+")";

}


function natsciHeader(){
	
var natsciList = new Array()
natsciList[0] = "http://www.sas.upenn.edu/home/assets/img/pages/natsci_header1.jpg"
natsciList[1] = "http://www.sas.upenn.edu/home/assets/img/pages/natsci_header2.jpg" 
	
var natsciImage = natsciList[(Math.round(Math.random()*(natsciList.length-1)))];
document.getElementById('topimage').style.backgroundImage = "url("+natsciImage+")";

}