For the extreme case of P(k) following an unbounded power law and assuming equal transmission across all edges, Pastor-Satorras and Vespignani [87] showed that the classic result of the epidemic threshold from mean field theory [10] breaks down. In real-transmission networks, the distribution of degree is often heavily skewed, and occasionally follows a power law [22] , but is always bounded, leading to the recovery of epidemic threshold, but one which is much lower than expected in evenly mixed populations [88] .