Cellular prion protein (PrPC) is present in the healthy adult brain. It is a presumably essential membrane protein but its cellular function is unclear. Like Ice-9 - the fictitious water allotrope in Kurt Vonnegut's Cat's Cradle, which "taught the atoms a novel way in which to stack, lock and crystallize until the oceans turned to ice" - cellular prion protein can, in a rare event, adopt a pathogenic and 'contagious' shape, PrPSc, which causes mad cow disease or Bovine Spongiform Encephalopathy (BSE). New variant Creutzfeldt Jakob Disease (vCJD) is the human malady attributed to eating beef tainted with BSE. In comparison to the UK epidemic (at the peak of which 37,280 cases of BSE were reported in the single year 1992), the emergence of four North American mad cows since May 2003 is minor yet still alarming. This work examines the USDA's response to indigenous BSE as manifested in "The Final Rule" (9 CFR 93-96, Jan 4, 2005) and questions whether current regulations are stringent enough to keep PrPSc out of cattle feed and human food.

Sheila Healy is a CISAC Science Fellow. She is currently analyzing USDA policy addressing Bovine Spongiform Encephalopathy (BSE) or mad cow disease. She recently finished a postdoctoral appointment in Stanley Prusiner's laboratory in the Department of Neurology at the University of California, San Francisco. There she studied the molecular and structural requirements for the conversion of cellular prion protein to its pathogenic form, the agent that causes BSE. She holds a doctoral degree in biochemistry and molecular and cellular biology from the University of Arizona.

We describe VEGA, a system for analyzing the vulnerability of an electric power grid to physical attacks by terrorists, and for planning mitigation efforts. VEGA (Vulnerability of Electric Grids Analyzer) consists of a bilevel optimization model and solution algorithm, a graphical user interface and a database. The optimization model implements a Stackelberg game in which (a) a group of terrorists attacks components of a power grid ("the system") so as to maximize the amount of load that must be shed (demand for power that goes unmet), and (b) the system operator minimizes that maximum by controlling the degraded system as best possible. We illustrate the basic model using realistic data and show how it can guide a system-upgrade plan to reduce vulnerability.

Actually, we at NPS are using similar techniques to study the vulnerability to attack of a variety of infrastructure systems. This talk will discuss the common approach, and provide two examples: (a) Finding "weak spots" in the Saudi Arabian crude-oil pipeline system and (b) protecting the Washington, DC subway system from a chemical or biological attack.

Dr. Kevin Wood is professor of operations research at the Naval Postgraduate School. At NPS since 1982, he has taught courses in networks and optimization and has published research on network reliability, mathematical programming and its applications, and on interdiction. His 1993 paper "Deterministic Network Interdiction" spurred renewed interest in applying analytical techniques to network and system interdiction, and has led to a series of papers on these topics, by him and by others. He is currently applying the methodology to critical infrastructure protection in general, and electric power grids in particular: Professor Wood has long-term research support from the Office of Naval Research as well as the Air Force of Scientific Research, and has been a visiting professor at Stanford University, the National Security Agency and the University of Auckland.