Figure 2

Temporal inhomogeneities. Temporal inhomogeneities affecting network growth. (a) The scaled inter-event time distribution of links $P(\tau )$, displaying a broader-than-Poissonian tail. For the plot, the edges have been divided into bins of different numbers of calls. The inter-event time distributions are then scaled by the average inter-event time $〈\tau 〉$ of each bin, following [12]. The non-scaling regime for low τ can be attributed to correlated calls, where an incoming call triggers an outgoing call within a short time period. (b) Total call rate in the network as a function of time, for the first 30 days, displaying the circadian and weekly patterns. Deep drops can be observed at night, while there are daily peaks, the highest of which appear on Friday evenings. Overall call activity is lower in the weekends, especially on Sundays.