Nonlinear Single-Armed Spiral Density Waves in Nearly Keplerian Disks

Single-armed, stationary density waves can propagate in very weakly self-gravitating gas disks dominated by a central mass. Examples include circumstellar disks of protostars and molecular disks in galactic nuclei. We explore the linear and nonlinear dynamics of such waves. Variational methods yield nonlinear versions of the dispersion relation, angular momentum flux, and propagation velocity in the tight-winding limit. The pitch angle increases with amplitude until the tight-winding approximation breaks down. We also find a series of nonlinear logarithmic spirals which is exact in the limit of small disk mass and which extends to large pitch angle.Comment: 16 pages, 3 figures. Uses mn.sty and mncite.sty. Accepted by MNRA

Coherent quantum transport in disordered systems: A unified polaron treatment of hopping and band-like transport

Quantum transport in disordered systems is studied using a polaron-based master equation. The polaron approach is capable of bridging the results from the coherent band-like transport regime governed by the Redfield equation to incoherent hopping transport in the classical regime. A non-monotonic dependence of the diffusion coefficient is observed both as a function of temperature and system-phonon coupling strength. In the band-like transport regime, the diffusion coefficient is shown to be linearly proportional to the system-phonon coupling strength, and vanishes at zero coupling due to Anderson localization. In the opposite classical hopping regime, we correctly recover that the dynamics are described by the Fermi's Golden Rule (FGR) and establish that the scaling of the diffusion coefficient depends on the phonon bath relaxation time. In both the hopping and band-like transport regimes, it is demonstrated that at low temperature the zero-point fluctuations of the bath lead to non-zero transport rates, and hence a finite diffusion constant. Application to rubrene and other organic semiconductor materials shows a good agreement with experimental mobility data.Comment: 19 pages, 4 figure

Migration, trapping, and venting of gas in a soft granular material

Gas migration through a soft granular material involves a strong coupling between the motion of the gas and the deformation of the material. This process is relevant to a variety of natural phenomena, such as gas venting from sediments and gas exsolution from magma. Here, we study this process experimentally by injecting air into a quasi-2D packing of soft particles and measuring the morphology of the air as it invades and then rises due to buoyancy. We systematically increase the confining pre-stress in the packing by compressing it with a fluid-permeable piston, leading to a gradual transition in migration regime from fluidization to pathway opening to pore invasion. We find that mixed migration regimes emerge at intermediate confinement due to the spontaneous formation of a compaction layer at the top of the flow cell. By connecting these migration mechanisms with macroscopic invasion, trapping, and venting, we show that mixed regimes enable a sharp increase in the average amount of gas trapped within the packing, as well as much larger venting events. Our results suggest that the relationship between invasion, trapping, and venting could be controlled by modulating the confining stress

Jeremy Lee in a Student Composers Recital

This recital and collection of original sheet music represent the culminating work for senior Music major (Contemporary Styles and Practices concentration) Jeremy Lee at Loyola Marymount University. The program features a selection of musical compositions that encapsulate different styles, genres, and unique compositional devices. Pieces also utilize a variety of arrangements and mediums, including compositions for multiple instruments and for film. Program notes for the included selections describe the historical influences and/or the personal stories and inspirations behind each piece. Performed live on April 21st, 2022, in Murphy Recital Hall

The effects of fantasy football participation on team identification and NFL fandom

Nearly 27 million people in North America played fantasy sports in 2009. This quantitative study examined how a person’s level of participation in fantasy football affects team identification, team loyalty, fandom of the National Football League (NFL), and consumer behavior. I also looked at whether fantasy football participants prefer a win by their fantasy team or their favorite team. An online survey was conducted using a snowball sample. I found higher participation levels result in higher team identification, higher team loyalty, and higher fandom, where fandom of the NFL is higher than team identification. Higher levels of participation also led to more time spent watching NFL games as well as more time spent online researching and updating their fantasy football team. I also found that over 41% of fantasy football participants prefer a win by their fantasy team, instead of their favorite team. A win preference of fantasy team resulted in lower team identification and team loyalty, which could have major implications on ticket sales, team merchandise sales, and sponsorship sales