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. 2012 May 17;8(5):e1002522. doi: 10.1371/journal.pcbi.1002522

Figure 2. Basic topological properties of the persistent networks as a function of culture age.

Figure 2

Number of nodes, links and edge density; calculated for 10 cultures at each age (DIV). Left: mean number of nodes and links found in the persistent networks. Note, although the number of nodes is a very different magnitude from the number of links, number of nodes was not found to change significantly (P = 0.272). Results for numbers of links at each age suggested an increase between younger (DIV 14 and DIV 21) and older (DIV 28 and 35) ages, however the increase was not significant (P = 0.074). Right: mean edge density of the persistent networks. Edge density (i.e. link density) quantifies the ‘cost’ of the network in terms of the number of links (m)/the maximum possible number of links ((n*(n−1)), given the number of nodes (n). Edge density was first calculated for each culture and then averaged over all cultures. Mean edge density at DIVs 21 to 35 was significantly higher than at DIV 14 (P = 0.012). In cases where no links were found the data were excluded from the analysis. All statistics quoted are for the n = 5–8 cultures valid for complex network analysis. Error bars represent ± standard error of mean (s.e.m, n = 5 to 8).