Department of Mathematics, Duke University, Science Dr, Durham, 27708, NC, USA. joperea@math.duke.edu.|Program in Computational Biology and Bioinformatics, Duke University, Durham, 27708, NC, USA. anastasia@deckard.edu.|Center for Systems Biology, Institute for Genome Sciences & Policy, Duke University, Durham, 27708, NC, USA. shaase@duke.edu.|Department of Mathematics, Duke University, Science Dr, Durham, 27708, NC, USA. harer@math.duke.edu.