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.
We wrongly attributed the photograph which accompanied this article (12 August, p 402) to Panos Pictures; it should have been credited to Format Photographers. We apologise for this error.
