Vice President Joe Biden waves as he walks onto the field before giving the commencement address ar the University of Pennsylvania's 257th Commencement, Monday, May 13, 2013, in Philade

 

              Vice President Joe Biden waves as he walks onto the field before giving the commencement address ar the University of Pennsylvania
Vice President Joe Biden waves as he walks onto the field before giving the commencement address ar the University of Pennsylvania's 257th Commencement, Monday, May 13, 2013, in Philadelphia. (AP Photo/Matt Rourke)