Funding for this research was provided by:
Air Force Office of Scientific Research (AFOSR FA9550-13-1-0047)
Exxon Mobil Foundation ((S18200000000256))
Received: 12 April 2018
Accepted: 17 May 2018
First Online: 6 June 2018
Ethics approval and consent to participate
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: The author declares that he has no competing interests.
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