1. Department of Geography, University of Lethbridge, 4401 University Drive, Lethbridge, Alberta T1K 3M4, Canada
2. Silv Econ, 913 Southwind Ct., Newmarket, Ontario L3Y 6J1, Canada
3. Teledyne Optech, 300 Interchange Way, Vaughan, Ontario L4K 5Z8, Canada