1. 122 Gilmore Hall, Biological and Ecological Engineering, Oregon State University, Corvallis, Oregon, USA 97331–3906.
2. Department of Agricultural and Biological Engineering, 1304 W. Pennsylvania Avenue, University of Illinois, Urbana, Illinois, USA 61801.
3. Eastern Regional Research Center, Agricultural Ressearch Service, USDA, Wyndmoor, Pennsylvania, USA 19038-8598.