[1] Harvard Univ, DEAS, Cambridge, MA 02138 USA
[2] Harvard Univ, Dept Phys, Cambridge, MA 02138 USA
[3] Amore Pacific R&D Ctr, Gyeonggi Do 446729, South Korea
[4] Philip Morris Inc, Res Ctr, INEST Grp, Richmond, VA 23298 USA
[5] Univ N Texas, Dept Phys, Denton, TX 76203 USA