1. Microsystems and Nanotechnology Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
2. Statistical Engineering Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, United States
3. Theiss Research, La Jolla, California 92037, United States
4. Building and Fire Sciences, United States Forest Service, Forest Products Laboratory, Madison, Wisconsin 53726, United States