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.
Scientific Reports 3, Article number: 2370 10.1038/srep02370 (2013); Published: August92013; Updated: December52013
An incorrect version of Figure 3 appears in the HTML version of this Article. The correct Figure 3 appears below as Figure 1. The PDF version of the Article is correct.
