The image shows part of the core of the network (directed), with
colors indicating the time-window, and arrows the direction (prompt to reply).
Blog-post (with link to data and software):
Also: See the video!
The video shows a directed reply-network colored to show circadian (24-hour scale, aggregate for 40 days) time-effects on Hacker News (news.ycombinator.net). Only small time-effects were found in the core of the network (minimum 3 reciprocated posts), shown here. In the periphery and on the aggregate level, effects were slightly larger, with greater reciprocity and transitivity (friends of friends becoming friends) in daily 3-hour time-windows than in random ones. And even the phased introduction of daylight saving time between the US and UK (UK is 2 weeks later) was found to have a measurable impact on the community-structure. See the full blog post and paper for more.