Resolution:
## Figure 3.
Panel A: relationship between the in-degree and the undirected-degree for each node;
observe that there is a negative correlation, i.e. in-hubs tend to have very few undirected
links and vice versa (insets correspond to covariance between the plotted variables).
Panel B: same as Panel A, but for the out-degree of the nodes; in this case, there
is a strong correlation between out-hubs and undirected-hubs. Panel C: relationship
between out- and in-degree for each node. The plot makes evident that nodes tend to
be either in-hubs or out-hubs, as the correlation between the degrees is basically
insignificant; moreover, large hubs tend to lay on the axes, i.e. they have a bias
to be pure "sources" (horizontal) or "sinks" (vertical). Another way to see this phenomenon
is presented in Panel D, where the maximum between the in- and out-degrees is plotted
against the absolute value of the difference between the same quantities. As the plot
shows, nodes tend to cluster near the identity line, which corresponds to pure sources
and sinks.
Cecchi |