var social1on = new Image(); social1on.src = 'images_usfsg/facebook_over.jpg';
var social1off = new Image(); social1off.src = 'images_usfsg/facebook.jpg';
var social2on = new Image(); social2on.src = 'images_usfsg/twitter_over.jpg';
var social2off = new Image(); social2off.src = 'images_usfsg/twitter.jpg';
var social3on = new Image(); social3on.src = 'images_usfsg/email_sm_over.jpg';
var social3off = new Image(); social3off.src = 'images_usfsg/email_sm.jpg';