[1] Univ Penn, Philadelphia, PA 19104 USA
[2] London Business Sch, London, England
[3] Bar Ilan Univ, IL-52100 Ramat Gan, Israel
[4] Emory Univ, Atlanta, GA 30322 USA
[5] Univ So Calif, Los Angeles, CA 90089 USA
[6] Univ Minnesota, Minneapolis, MN 55455 USA