Thermodynamics of Fluid Polyamorphism

“Fluid polyamorphism” is the existence of two alternative amorphous structures in a single-component fluid. It is found in very different materials, such as silicon, phosphorus, cerium, and hydrogen, usually at extreme conditions. In particular, this phenomenon is hypothesized in metastable supercooled water, inaccessible for direct bulk-water experiments because it is predicted to be below the empirical limit of homogeneous ice nucleation. I present a generic phenomenological approach to describe polyamorphism in a single-component fluid, applicable regardless of the microscopic origin of the phenomenon. To specify this approach, I consider a fluid with “chemical reaction” equilibrium between two competing interconvertible states or structures. This approach for the physics of liquid-liquid separation in a single-component fluid is based on a discrete nature of two distinct structures. The approach qualitatively describes the global phase diagram of a fluid, with both vapor-liquid and liquid-liquid equilibria, as well as peculiar properties of polyamorphic fluids

Angler Perception and Population Dynamics of the Northern Snakehead (Channa argus) in the Potomac River & Tributaries

Our research sought to address the extent to which the northern snakehead (Channa argus), an invasive fish species, represents a threat to the Potomac River ecosystem. The first goal of our research was to survey the perceptions and opinions of recreational anglers on the effects of the snakehead population in the Potomac River ecosystem. To determine angler perceptions, we created and administered 113 surveys from June – September 2014 at recreational boat ramps along the Potomac River. Our surveys were designed to expand information collected during previous surveys conducted by the U.S. Fish and Wildlife Service. Our results indicated recreational anglers perceive that abundances and catch rates of target species, specifically largemouth bass, have declined since snakehead became established in the river. The second goal of our research was to determine the genetic diversity and potential of the snakehead population to expand in the Potomac River. We hypothesized that the effective genetic population size would be much less than the census size of the snakehead population in the Potomac River. We collected tissue samples (fin clippings) from 79 snakehead collected in a recreational tournament held between Fort Washington and Wilson’s Landing, MD on the Potomac River and from electrofishing sampling conducted by the Maryland Department of Natural Resources in Pomonkey Creek, a tributary of the Potomac River. DNA was extracted from the tissue samples and scored for 12 microsatellite markers, which had previously been identified for Potomac River snakehead. Microsatellite allele frequency data were recorded and analyzed in the software programs GenAlEx and NeEstimator to estimate heterozygosity and effective genetic population size. Resampling simulations indicated that the number of microsatellites and the number of fish analyzed provided sufficient precision. Simulations indicated that the effective population size estimate would expect to stabilize for samples > 70 individual snakehead. Based on a sample of 79 fish scored for 12 microsatellites, we calculated an Ne of 15.3 individuals. This is substantially smaller than both the sample size and estimated population size. We conclude that genetic diversity in the snakehead population in the Potomac River is low because the population has yet to recover from a genetic bottleneck associated with a founder effect due to their recent introduction into the system

A Pilot Study of a Collaborative Palliative and Oncology Care Intervention for Patients with Head and Neck Cancer.

BACKGROUND: Palliative care improves symptoms and coping in patients with advanced cancers, but has not been evaluated for patients with curable solid malignancies. Because of the tremendous symptom burden and high rates of psychological distress in head and neck cancer (HNC), we evaluated feasibility and acceptability of a palliative care intervention in patients with HNC receiving curative-intent chemoradiation therapy (CRT). METHODS: This was a prospective single-arm study in HNC patients receiving CRT at a single center in the United States. The intervention entailed weekly palliative care visits integrated with oncology care with a focus on symptoms and coping. The primary outcome was feasibility, defined as a >50% enrollment rate with >70% of patients attending at least half of the visits. To assess acceptability, we collected satisfaction ratings post-intervention. We also explored symptom burden, mood, and quality of life (QOL). RESULTS: We enrolled 91% (20/22) of eligible patients. Patients attended 133 of 138 palliative care visits (96%); all 20 attended >85% of visits. Eighteen of 19 (95%) found the intervention “very helpful” and would “definitely recommend” it. QOL and symptom burden worsened from baseline to week 5, but subsequently improved at one-month post-CRT. Overall, patients valued the one-on-one format of the intervention and receipt of additional care. CONCLUSIONS: Our palliative care intervention during highly morbid CRT was feasible and acceptable with high enrollment, excellent intervention compliance, and high patient satisfaction. Future randomized studies will further explore the impact on patient-reported outcomes and health care utilization