This award is made as part of the FY 2026 Mathematical Sciences Postdoctoral Research Fellowships Program. Each of the fellowships supports a research and training project at a host institution in the mathematical sciences, including applications to other disciplines such as Artificial Intelligence and Quantum Information Science, under the mentorship of a sponsoring scientist. The title of the project for this fellowship to Brandis Whitfield is “The Geometries of End-Periodic Mapping Tori and Subgroups of the Mapping Class Group”. The host institution for the fellowship is the University Wisconsin - Madison and the sponsoring scientist is Autumn Kent. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.