Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
Left: Tweet density T versus population density ρ, slope of the line is α. Middle: User density U versus population density ρ, slope of the line is β. Right: Tweet density T versus user density U, slope of the line is γ. Using a 40 × 40 grid.
