Funding for this research was provided by:
Air Force Office of Scientific Research (FA9550-13-1-0047)
ExxonMobil Foundation (S18200000000256)
Received: 17 August 2017
Accepted: 20 October 2017
First Online: 30 October 2017
Ethics approval and consent to participate
: The author declares that he has no competing interests.
: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.