1. Atmospheric scientist specializing in lidar and boundary layer meteorology at the National Center for Atmospheric Research, Boulder, Colorado.
2. Director of the Chemical, Biological, Radiological, Nuclear, and Explosives Directorate, Pentagon Force Protection Agency, Arlington, Virginia.
3. Chief Science Officer of the Chemical, Biological, Radiological, Nuclear, and Explosives Directorate, Pentagon Force Protection Agency, Arlington, Virginia.
4. Fellow of the Center for a New American Security, and the Nunn Prize Fellow at the Center for Strategic and International Studies, Washington, DC.