Professor, College of William and Mary, 2012- Associate Professor, College of William and Mary, 2006-2012 Arts and Sciences Term Distinguished Associated Professor of Mathematics, College of William and Mary, 2010-2013 Assistant Professor, College of William and Mary, 2000-2006 Visiting Assistant Professor, Tulane University, 1998-2000 Guest Professor, Harbin Normal University, 2001- Longjiang Scholar Professor, Harbin Normal University, 2006-2009