The Mathematical Sciences Postdoctoral Research Fellowships are awards to recent recipients of doctoral degrees. The fellowship is designed to provide 24 months of support divided into 18 academic months and 3 periods of two summer months. The recipient has the option of a Research Instructorship which allows the 18 months of academic support to be taken as 9 months of full-time support and 18 months of half-time support. Mathematical Sciences Postdoctoral Research Fellowship awards allow fellows to choose research environments that will have maximal impact on their future scientific development. Mark Hartmann received his doctoral degree from Cornell University, and will pursue research in the area of pure and applied mathematics, specifically, to investigate polyhedra arising as local environments (Voronoi regions) of atoms in crystalline structures and dense packings of spheres, under the guidance of J. Scott Provan at the University of North Carolina, Chapel Hill.