1. Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, Lawrence Livermore National Laboratory, Livermore, California 94551, Department of Engineering, University of Cambridge, Cambridge, UK CB3 0FA, Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin-Dahlem, Germany, Center for Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, and Department of Mechanical Engineering,...