<p>Biological warfare is the subject of today's "Winds of Change" features. Lady Margaret Thatcher leads off in typically clear and inspirational style. The recently-passed Bioterrorism Preparedness Act of 2001 follows - it's a start, but large gaps remain. We look at the act and the gaps, and set out the 10-point plan for change. In-depth briefings on anthrax and smallpox round out today's features.</p>