1. Department of Bioengineering; Imperial College; London United Kingdom
2. Materials Sciences Division; Lawrence Berkeley National Laboratory; Berkeley CA USA
3. Department of Materials Science and Engineering; University of California Berkeley; Berkeley CA USA
4. Department of Earth Science and Engineering; Imperial College; London United Kingdom
5. Department of Orthopaedic Surgery; University of California San Francisco; San Francisco CA USA
6. Department of Radiology and Biomedical Imaging; University of California San Francisco; San Francisco CA USA