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.
Due to errors introduced during the production process, Figure 1 and Figure 2 are incomplete. The full, correct figures can be found here:
Figure 1: http://plosone.org/corrections/pone.0033023.g001.cn.tif
Figure 2: http://plosone.org/corrections/pone.0033023.g002.cn.tif
Competing Interests: No competing interests declared.
View on publisher site
