Funding for this research was provided by:
National Science Foundation (DGE - 1256259)
National Aeronautics and Space Administration (NNX12AO37G)
National Science Foundation (EAR-0943965, EAR-1347190)
Article History
Received: 2 November 2015
Accepted: 21 June 2016
First Online: 9 July 2016
Compliance with ethical standards
:
: The authors declare that they have no conflict of interest.