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.
Example of an SPA representation on a square lattice system. A lattice site can be occupied by an ssDNA molecule or left empty. At each cycle, a molecule can either make a copy on one of the nearest neighbor empty sites or stay inactive. When all four nearest neighbor sites are occupied (molecules in gray), the molecule cannot produce copies anymore.
