David Nelson, PhD
Arthur K. Solomon Professor of Biophysics; Professor of Physics and Applied Physics
Department of Molecular and Cellular Biology, Faculty of Arts and Sciences
Examining the intersection of biology, chemistry, and physics
Using principles of physics to make predictions about the behavior and function of biological systems, such as denaturation of DNA and protein packing of viruses. Investigates the physics of polymers, membranes, and flux liquids.
Commercial Opportunities
Findings of Prof. Nelson's research are applicable to material sciences such as fluids, liquid crystals, polymers, phase transitions, glasses, superfluids, and superconductors.
Current Research Interests
Prof. Nelson's research focuses on the intersection of biology, chemistry, and physics. He has investigated the physics and chemistry of condensed matter, along with geometry and statistical mechanics. His current interests include vortex physics, the physics of flexible sheet polymers and membranes, entangled flux liquids in high-temperature superconductors, topological defects on frozen topographies, and biophysics.
Prof. Nelson has developed a theory of force-induced denaturation of double-stranded DNA with David Lubensky, one of his students. When DNA replicates, the two strands of bases "un-zip," allowing additional bases to pair with each strand creating a new DNA duplex on each side. Prof. Nelson's theory links the sequence heterogeneity of a segment of DNA and the dynamics of the un-zipping fork created during DNA replication. In addition, sequence heterogeneity may also affect the dynamics of the motor proteins involved in DNA replication (helicases, exonulceases and RNA polymerases). Prof. Nelson has also studied how the shape of viruses is dictated by the virus' size.
In addition, Prof. Nelson is interested in theoretical problems in the areas of statistical mechanics and condensed matter physics. Specifically, these research efforts focus on fluids, liquid crystals, polymers, phase transitions, glasses, superfluids, superconductors and problems in biophysics.
Research Expertise
Prof. Nelson's early work investigated population dynamics and how these are affected by varying growth and convection rates. He used this work to derive predictions for population spread in space- and time-dependent environments. Prof. Nelson has also studied the structure of metallic glasses and theories regarding the structure of icosahedral quasicrystals. One of his long-term interests is in the statistical mechanics of two-dimensional melting. Prof. Nelson and his colleague Bertrand I. Halperin constructed a theory of dislocation-mediated melting in two dimensions, involving a fourth phase of matter in between the solid and liquid phases. This fourth phase was confirmed in later experiments involving thin films and bulk liquid crystals.
Prof. Nelson has also studied flux line entanglement in high temperature superconductors. Usually, magnetic flux lines form a regular array. However, high magnetic fields cause thermal fluctuations that make these flux line arrays become convoluted and irregular. The physics of these flux lines has important implications for the application of superconductors.