1. Department of Physics and Astronomy, University of Nebraska—Lincoln, Lincoln, Nebraska 68588-0299, United States
2. Department of Physics, Institute of Basic Science, Daegu University, Gyeongsan 712-714, Korea
3. Department of Physics, University of Central Florida, Orlando, Florida 32816, United States
4. Department of Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, Tennessee 37996, United States
5. Center for Molecular Biophysics, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
6. University of California,
Riverside, Pierce Hall, Riverside, California 92521, United States
7. Department of Physics, University of California, Berkeley, Berkeley, California 94720, United States