SIS on heterogeneous activity networks — threshold depends on ⟨a²⟩/⟨a⟩
Prevalence: 0% | Threshold: computing...
Activity-driven network model (Perra et al. 2012): N=300 nodes drawn from F(a) ∝ a^(−γ).
Each timestep: each node i is active with probability aᵢ·Δt and forms m=2 random links.
SIS dynamics: infected nodes infect neighbors at rate β; recover at rate μ.
The epidemic threshold is β/μ > ⟨a⟩/⟨a²⟩ — heavy-tailed activity (small γ) dramatically
lowers the threshold. Green line: susceptible fraction. Red line: infected fraction.
The vertical dashed line shows the theoretical threshold.