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.
The error bars represent standard error of the mean (SEM). Bars with differing superscripts are statistically different (P<0.05).
