Source-sink dynamics in a two-patch SI epidemic model with life stages and no recovery from infection

The paper’s model, thresholds, and equilibrium formulas match the candidate’s derivations patch-by-patch. Both use the block-triangular Jacobian to split infection and demography, recover the infected eigenvalues {βi−µI, −µI}, define R0,i = βi/µI, and derive the same endemic relations with λi = Rα/(R0,i+Rs−1). The paper presents the same I1* formula (normalized) and the same quadratic for I2*; the candidate reaches these with slightly different linear-algebraic phrasing but identical conclusions. Minor gaps in the paper (asserting B1,C1>0; numerical—rather than analytic—stability of endemic points) do not affect the correctness of the reported thresholds and equilibria that the candidate re-derives. See model (1) and block structure remark, disease-free analyses, patch‑1 endemic formula (Prop. 2; Appendix B), and the patch‑2 quadratic (Prop. 4) in the paper .