Figure 15.
Schematic view of interaction between different number of PCSUs: a unit (a); two units (b); three units (c).
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.