Structural efficiency average degrees.

Structural efficiency average degrees as defined in Eq. (1) and Eq. (3) for the Internet customer-provider relationships network, the synaptic neuronal network of C. elegans, and the metabolism of the bacterium E. coli, and their randomized counterparts (values are average±standard deviation rounded off to the first significant figure). Infinite values come from the fact that all peripheral nodes are directly connected to the core.