Abstract: In astronomy, we observe many massive explosions. Some stars end their lives in catastrophic explosions called supernovae. The dead embers of stars like our Sun can interact with a companion star to trigger a particular type of supernova called a type Ia supernova. These explosions are so fantastically bright that we can see them over "cosmic" distances spanning an appreciable fraction of the size of the Universe. We use these explosions as "cosmic candles" to measure the evolution of the Universe. In this talk, I will give an overview of these fantastic events and discuss my work modeling them on supercomputers.

Abstract: We present photometric data of the classical nova and eclipsing variable V723 Cas (Nova Cas 1995), over a span of ten years (2006 through 2016) taken with the 0.9-m telescope at Lowell Observatory, operated as the National Undergraduate Research Observatory (NURO) on Anderson Mesa near Flagstaff, Arizona. A photometric analysis of the data produced light curves in the optical bands (Bessel B, V, and R filters). The data analyzed here reveal an asymmetric light curve, the overall structure of which exhibits pronounced evolution including a decrease in magnitude from year to year. The latest light curve shows a dramatic change from those observed in previous years. This coincides with the nova shutting off in X-rays.

Abstract: The classical macroscopic presentation of the second law of thermodynamics is an elegant but abstract sequence of very specific thought experiments that utilize reversible processes occurring within heat engines operating between infinite temperature reservoirs. The length, specificity and complexity of this sequence may hamper the understanding of important concepts such as exergy and entropy. The pedagogical problems of this approach have been discussed, followed by an alternative presentation wherein second law concepts and formulations have been derived from thought experiments that use real, rather than imaginary processes. The thought experiments involve classifying heat transfer at any local point for any arbitrary process involving work-heat interactions into different categories, and then collecting terms for each category throughout the control volume in order to relate property changes to external heat transfer and/or work. They embrace the spatial non-uniformity present in any real process, are consistent with contemporary computational approaches, and can potentially serve as building blocks for the development of computational thinking in students.

Abstract: Physicists and Mathematicians are fascinated by Music. Musicians are also fascinated by Math and have used it to strengthen the structure of their compositions. Meet Debussy, Bartok, Stockhausen and Fibonacci and the Golden Section.

Abstract: Biology naturally produces a wide range of polymers that are often forced to function in highly concentrated environments. These ubiquitous biopolymer networks display complex and intriguing viscoelastic properties similar to those we find in the squishy materials in and all around us. Our lab uses single-molecule microscopy techniques to elucidate the molecular mechanics underlying the unique viscoelastic properties of networks comprised of three biopolymers of fundamental importance: DNA, actin, and microtubules. We use optical tweezers to push and pull microspheres through these networks and measure the force the biopolymers impart on the spheres in response to the microscale strains. We also use fluorescence microscopy to track biopolymers in these systems and characterize network architecture. I will discuss three of our recent experiments that highlight these techniques and reveal the fascinating impacts of macromolecular flexibility, topology, and concentration on biopolymer transport, conformation, and nonlinear response to strain. I will also discuss how I incorporate these methods and research topics into our research-intensive undergraduate biophysics major.

Abstract: We present time- and spatially-resolved observations of the inner solar corona in the 5303 A line of Fe XIV, taken during the 21 August 2017 solar eclipse from a field observing site in Crossville, TN. These observations are used to characterize the intensity variations in this coronal emission line. We will compare results with oscillation predictions from models for heating the corona by magnetic wave dissipation. The observations were taken with two refracting telescopes. One system used a custom-built 5 A FWHM filter centered on the Fe XIV coronal spectral line and an Atik Titan camera for image collection. The setup produced images covering approximately 20% of the entire solar limb centered near the emerging sunspot complex AR 2672. We obtained images with a frame rate of 2.36 Hz, for a total of 361 images during the 152 seconds of totality. An identical, co-aligned telescope/camera system observed the same portion of the solar corona, but with a 100 A FWHM filter centered on a wavelength of 5400 A. These simultaneous observations are used as a control to monitor brightness variations not related to coronal line oscillations. We discuss the challenges of building a remote observing site on a golf course ten hours from campus, as well as describe the eclipse experience for those 7 students, two faculty members, and a few other interested parties who were involved on the eclipse expedition.

Abstract: Non-spherical particles in turbulent flows are important in a wide range of problems including ice crystals in clouds, fibers in paper-making, marine plankton, and additives for turbulent drag reduction. We have recently developed experimental methods for precise tracking of the position and orientation of non-spherical particles in intense 3D turbulence. Using 3D printed particles, we can fabricate a wide range of shapes and explore how particle orientation and rotation are affected by particle shape. We find particles are strongly aligned by the turbulence. A simple picture in which particles are aligned by the fluid stretching they experience explains many of the key observations about how particles align and rotate. This same picture sheds new light on some old problems about how vorticity aligns with the strain rate tensor in turbulent flows. It has also allowed us to create a fascinating particle shape which we call a chiral dipole that shows a preferential rotation direction in isotropic turbulent flow.