1. Visiting Scholar, Dept. of Civil and Environmental Engineering, Rice Univ., 6100 Main St., 202 Ryon Lab, Houston, TX 77005; formerly, Graduate Student, School of Engineering, Univ. of Vermont, 33 Colchester Ave., 103 Votey Hall, Burlington, VT 05405.
2. Assistant Professor, School of Engineering, Univ. of Vermont, 33 Colchester Ave., 103 Votey Hall, Burlington, VT 05405 (corresponding author).