1. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599
2. Department of Biomedical Engineering, University of North Carolina, Chapel Hill, North Carolina 27599
3. Xintek, Inc., 308 W Rosemary St., Chapel Hill, North Carolina 27516
4. Curriculum in Applied and Materials Sciences, University of North Carolina, Chapel Hill, North Carolina 27599
5. Department of Radiology, School of Medicine, University of North Carolina, Chapel Hill, North Carolina 27599
6. Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599 and Curriculum in Applied and Materials Sciences, University of North Carolina, Chapel Hill, North Carolina 27599