1. Department of Mechanical Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA
2. School of Optical and Electronic Information, and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 China
3. Department of Anesthesiology Critical Care and Pain Medicine Massachusetts General Hospital Harvard Medical School Boston MA 02115 USA
4. Department of Anesthesiology and Perioperative Medicine Mayo Clinic Rochester MN 55905 USA
5. Department of Civil and Environmental Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA