1. Assistant Professor, Mechanical and Industrial Engineering, Univ. of Toronto, 5 King's College Rd., Toronto, ON, Canada M5S 3G8.
2. Associate Professor, Industrial and Systems Engineering, Civil and Environmental Engineering, Univ. of Washington, G5 Mechanical Engineering Bldg., Box 352650, Seattle, WA 98195 (corresponding author).
3. Professor, Industrial and Systems Engineering, 3007 Mechanical Engineering Bldg., Univ. of Wisconsin-Madison, Madison, WI 53706.