NSF NeXUS: A New Model for Accessing the Frontiers of Ultrafast Science - L. Robert Baker; Louis F. DiMauro; Claudia Turro; Jay A. Gupta; Roland K. Kawakami; Thomas K. Allison; Theodore J. Ronningen; Timothy D. Scarborough; Vyacheslav Leshchenko; Seth S. Shields; John E. Beetar (ACS Central Science)