Genetics, modularity, mutation rate, horizontal gene transfer. Dr. Deem's specialty is statistical mechanics, specifically the computer simulation of complex molecular systems. He works in the areas of evolution, immunology, and materials. Dr. Deem has developed methods to quantify vaccine effectiveness and antigenic distance for influenza, methods to sculpt the immune system to mitigate immunodominance in dengue fever, a physical theory of the competition that allows HIV to escape from the immune system, and the first exact solution of a mathematical model of evolution that accounts for cross-species genetic exchange. Dr. Deem's recent study, published in the December 2007 'Physical Review Letters', found that genetic modularity arises spontaneously because of the selective pressure of a changing environment and the existence of horizontal gene transfer.