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Division of Natural Sciences & MathematicsDepartment of Physics & Astronomy

Research

Physics & Astronomy

Faculty Research

Astronomy and Astrophysics

Astronomy research began at DU in 1880 with Professor Howe's solutions to the Kepler Problem in orbital mechanics and featured completion of historic Chamberlin Observatory with its 0.5 meter aperture Clark-Saemuller f/15 refractor. This facility is still in use for classes and public instruction, and has been joined by newer telescopes including atop 14,148 ft Mt.Evans, the Student Astronomy Lab and internet/space based telescopes. Dr. Robert Stencel uses these telescopes for instructional use with students and research into stellar evolution and long period binary stars.

Dr. Jennifer Hoffman investigates core-collapse supernovae, using the combined techniques of observational spectropolarimetry and three-dimensional numerical radiative transfer modelling to probe the geometrical configurations of gas and dust surrounding these explosive stars. She has also applied these techniques to newly formed protostars, interacting binary systems, and evolved mass-losing variable stars, aiming to trace the structure of circumstellar material and the ways it mediates between a star and its environment over the course of the star's life cycle.

Dr. Toshiya Ueta's research interests include stellar evolution (especially the late stages from the red giant to the planetary nebula phases), astropaleontology (study of the past evolution of astronomical sources through investigation of the circumsource material distribution), radiative transfer in dusty media, infrared observations of dusty media, and astromineralogy (composition and formation of circumstellar and interstellar dust). He is an active user of various space- and ground-based observatories around the world such as Hubble Space Telescope and Mauna Kea and ESO Observatories.

Biophysics

Dr. Kingshuk Ghosh's work is in the area of theoretical statistical mechanics of biopolymers. He is particularly interested in developing theoretical models for thermodynamics and kinetics of protein folding and protein aggregation to better understand the origin of several neurodegenerative diseases and help in the formulation of protein therapeutics. His other interest is to model non-equilibrium systems where fluctuations are important. This is particularly important in the study of dynamics in the fields of nano and bio-science, where small number fluctuations can determine macroscopic behaviors. The focus of his work is both to lay the foundation for dynamical processes where fluctuations are significant, and more importanly, to apply the theory to the types of single molecule experiments that are beginning to appear routinely in biology.

Dr. Dinah Loerke's research interests focus on quantitative biophysical approaches to experimental cell biology. In particular, she is interested in the study of biological processes at the single cell level through the analysis of spatiotemporal dynamics of subcellular events. Her approach combines fluorescence live-cell microscopy, computational image processing, and quantitative and statistical data analysis. Special emphasis lies on large and heterogeneous data populations, with the goal of extracting mechanistic and molecular information through measurement and inter-correlation of different readouts. Of particular interest to her are the relationship between cytoskeletal dynamics and endocytosis, and the integration of biochemical and mechanical signaling at the level of the cell membrane.

Dr. Sean Shaheen is new to the field of biophysics. Branching out from his ongoing work on molecular materials for organic solar cells, he is interested in studying protein and enzyme interactions in biosynthetic pathways. He works with Dr. David Patterson in Biological Sciences and Dr. Kingshuk Ghosh in Physics and Astronomy to study the kinetics and systems-properties of the purine biosynthetic pathway. This fundamental reaction pathway exhibits a unique form of collective behavior among the enzymes involved, which can come together to form a macromolecular "purinosome" under the correct environmental conditions. He is interested in this and other forms of cooperative behavior across length scales in biology. Additionaly, he studies methods for statistical analysis of biological systems and networks and has several ongoing collaborations in this area. Further information can be found on his group homepage.

Molecular and Celluluar Biophysics

The Physics and Astronomy Department is part of the Molecular and Cellular Biophysics program at DU. This program promotes interdisciplinary research among Physics and Astronomy, Chemistry, and Biological Sciences, and offers a doctoral degree in Molecular and Cellular Biophysics. Interested students should apply directly to the program. For more information on the biophysics program, please contact Dr. Kingshuk Ghosh (kghosh@du.edu).

Condensed Matter and Materials Physics

Condensed matter physics (CMP) is the study of materials or systems in solid, liquid, or granular form. CMP at DU is a highly interdisciplinary effort, with professors collaborating with biologists, chemists, engineers and materials scientists on problems ranging from complex systems and nonlinear dynamics, to the magnetic, thermal, structural, chemical, spectroscopic, and electronic properties of nanoscale and molecular systems.

Dr. Barry Zink's research interests focus on using micro- and nanofabrication techniques to control and measure the thermal, magnetic and electronic properties of systems to study the fundamental physics of new materials and apply this knowledge for new technologies. Much of his recent fundamental work has focused on studying electronic, magnetic or vibrational states of amorphous solids. His current emphasis is on two areas: measuring thermal transport and thermopower of thin films and nanostructures from 300 mK to above 300 K, and studying new physics and new applications of high resolution microcalorimeter x-ray and gamma-ray detectors.

Dr. Sean Shaheen's condensed matter research is in the area of organic and nanostructured semiconductor physics and organic photovoltaic (OPV) devices. His work entails design of new molecular light absorbers and charge transporters, and studies on the nature of charge transport and recombination in donor-acceptor blends, the effects of donor-acceptor morphology on device physics, novel OPV device architectures, modeling of OPV device performance, and large-area module development. He is currently also examining the use of organic semiconductors for dynamic and nonlinear electronics. Futher information can be found on his group homepage.

Dr. Mercedes Calbi studies gases adsorbed on and inside carbon nanotube bundles, Bose-Einstein condensation in low-dimensional systems, and forces between nanosize particles. Her theoretical approaches are based on statistical and quantum mechanical methods and include density functional techniques for liquid helium, grand canonical Monte Carlo simulations, and kinetic Monte Carlo schemes.

Dr. Mark Siemens' research interests lie in the use of ultrafast lasers to understand transport of fundamental energy carriers in and near nanostructures. Using laser pulses as short as a few femtoseconds (10^-15 s) allows for spectroscopic measurement of electron, hole, and phonon transport at their fundamental time scales. His work studies these processes in a variety of nanoscale systems, such as quantum-confined semiconductor systems and metal-on-insulator nanowires. These energy transfer processes are relevant to heat-sinking of nanocircuits and solar energy conversion.

Dr. Davor Balzar's research interests are mainly in studies of materials' properties by diffraction methods. The focus is on strain and defect determination through the measurement and modeling of diffraction line broadening, and development of methods for analysis of residual strain/stress, texture, and defects in materials. Materials currently of interest include ferroelectrics, wide band-gap semiconductors, and nanocomposites for biomedical applications.

Dr. Robert Amme's Environmental Materials Laboratory is engaged in studying the benefits of recycling scrap tire rubber into several very useful products. Among these products are radiation shielding, asphalt rubber blends for improving roadway durability and reduction of traffic noise, rubberized trails for walking, jogging, and bicycling, and safer playgrounds employing rubber + polymer binders. Used tires are generated at the rate of roughly one tire per person per year, and too often end up in landfills as a potentially hazardous waste. Measuring the mechanical and chemical properties of ground tire rubber blended with asphaltic and polyoctenamer materials are a major thrust of this research.