[1] Luther Coll, Decorah, IA 52101 USA
[2] Univ Minnesota, Minneapolis, MN 55455 USA
[3] Northwestern Univ, Evanston, IL 60208 USA
[4] Univ Puerto Rico, Mayaguez, PR 00681 USA
[5] Purdue Univ, W Lafayette, IN 47907 USA
[6] Rensselaer Polytech Inst, Troy, NY 12180 USA
[7] Rice Univ, Houston, TX 77005 USA
[8] Univ Rochester, Rochester, NY 14627 USA
[9] Syracuse Univ, Syracuse, NY 13244 USA
[10] Wayne State Univ, Detroit, MI 48202 USA
[11] Carleton Univ, Ottawa, ON K1S 5B6, Canada
[12] Carnegie Mellon Univ, Pittsburgh, PA 15213 USA
[13] Univ Chicago, Enrico Fermi Inst, Chicago, IL 60637 USA
[14] Cornell Univ, Ithaca, NY 14853 USA
[15] Univ Florida, Gainesville, FL 32611 USA
[16] George Mason Univ, Fairfax, VA 22030 USA
[17] Univ Illinois, Urbana, IL 61801 USA
[18] Indiana Univ, Bloomington, IN 47405 USA
[19] Univ Kansas, Lawrence, KS 66045 USA
[20] Univ Oxford, Oxford OX1 3RH, England
[21] Univ Bristol, Bristol BS8 1TL, Avon, England