[1] Penn State Univ, University Pk, PA 16801 USA
[2] Boise State Univ, Boise, ID 83725 USA
[3] Oregon State Univ, Corvallis, OR 97331 USA
[4] IBM Microelect, Essex Jct, VT 05452 USA
[5] NIST, Gaithersburg, MD 20899 USA
[6] Vienna Univ Technol, A-1040 Vienna, Austria