1. Division of Engineering and Applied Science, California Institute of Technology, Pasadena, California 91125, USA
2. Department of Mechanical and Process Engineering (D-MAVT), Swiss Federal Institute of Technology (ETH), 8092 Zurich, Switzerland
3. Samsung Advanced Institute of Technology (SAIT), Samsung Electronics, Co., Ltd., 130 Samsung-ro, Yeongtong-gu, Suwon-si, Gyeonggi-do 443-803, South Korea