1. Renaissance Computing Institute (RENCI), University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
2. Department of Computer Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
3. Odum Institute for Research in Social Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
4. Department of Political Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
5. Department of Mathematics, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.
6. School of Information and Library Science, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina.