Pressure-energy correlations in liquids. V. Isomorphs in generalized Lennard-Jones systems

This series of papers is devoted to identifying and explaining the properties of strongly correlating liquids, i.e., liquids with more than 90% correlation between their virial W and potential energy U fluctuations in the NVT ensemble. Paper IV [N. Gnan et al., J. Chem. Phys. v131, 234504 (2009)] showed that strongly correlating liquids have "isomorphs", which are curves in the phase diagram along which structure, dynamics, and some thermodynamic properties are invariant in reduced units. In the present paper, using the fact that reduced-unit radial distribution functions are isomorph invariant, we derive an expression for the shapes of isomorphs in the WU phase diagram of generalized Lennard-Jones systems of one or more types of particles. The isomorph shape depends only on the Lennard-Jones exponents; thus all isomorphs of standard Lennard-Jones systems (with exponents 12 and 6) can be scaled onto to a single curve. Two applications are given. One is testing the prediction that the solid-liquid coexistence curve follows an isomorph by comparing to recent simulations by Ahmed and Sadus [J. Chem. Phys. v131, 174504 (2009)]. Excellent agreement is found on the liquid side of the coexistence, whereas the agreement is worse on the solid side. A second application is the derivation of an approximate equation of state for generalized Lennard-Jones systems by combining the isomorph theory with the Rosenfeld-Tarazona expression for the temperature dependence of potential energy on isochores. It is shown that the new equation of state agrees well with simulations.Comment: 12 pages, 14 figures, Section on solid-liquid coexistence expande

Facilitators of multisector collaboration for delivering cancer control interventions in rural communities: A descriptive qualitative study

PURPOSE AND OBJECTIVES: Multisector collaboration is a widely promoted strategy to increase equitable availability, access, and use of healthy foods, safe places for physical activity, social supports, and preventive health care services. Yet fewer studies and resources exist for collaboration among governmental and nongovernmental agencies to address public problems in rural areas, despite an excess burden of risk factors for cancer morbidity and mortality. We aimed to learn about cancer prevention activities and collaboration facilitators among rural informal interagency networks. EVALUATION METHODS: In 2020, researchers conducted semistructured interviews with staff from rural public health and social services agencies, community health centers, and extension offices. Agency staff were from 5 service areas across 27 rural counties in Missouri and Illinois with high poverty rates and excess cancer risks and mortality. We conducted a thematic analysis to code interview transcripts and identify key themes. RESULTS: Exchanging information, cohosting annual or one-time events, and promoting other agencies\u27 services and programs were the most commonly described collaborative activities among the 32 participants interviewed. Participants indicated a desire to improve collaborations by writing more grants together to codevelop ongoing prevention programs and further share resources. Participants expressed needs to increase community outreach, improve referral systems, and expand screenings. We identified 5 facilitator themes: commitment to address community needs, mutual willingness to collaborate, long-standing relationships, smaller community structures, and necessity of leveraging limited resources. Challenges included lack of funding and time, long travel distances, competing priorities, difficulty replacing staff in remote communities, and jurisdictional boundaries. Although the COVID-19 pandemic further limited staff availability for collaboration, participants noted benefits of remote collaborative meetings. IMPLICATIONS FOR PUBLIC HEALTH: Rural areas need consistent funding and other resources to support health-improving multisector initiatives. Existing strengths found in the rural underresourced areas can facilitate multisector collaborations for cancer prevention, including long-standing relationships, small community structures, and the need to leverage limited resources

Phase-field model for grain boundary grooving in multi-component thin films

Polycrystalline thin films can be unstable with respect to island formation (agglomeration) through grooving where grain boundaries intersect the free surface and/or thin film-substrate interface. We develop a phase-field model to study the evolution of the phases, composition, microstructure and morphology of such thin films. The phase-field model is quite general, describing compounds and solid solution alloys with sufficient freedom to choose solubilities, grain boundary and interface energies, and heats of segregation to all interfaces. We present analytical results which describe the interface profiles, with and without segregation, and confirm them using numerical simulations. We demonstrate that the present model accurately reproduces the theoretical grain boundary groove angles both at and far from equilibrium. As an example, we apply the phase-field model to the special case of a Ni(Pt)Si (Ni/Pt silicide) thin film on an initially flat silicon substrate.Comment: 12 pages, 5 figures, submitted to Modelling Simulation Mater. Sci. En

Strong pressure-energy correlations in van der Waals liquids

Strong correlations between equilibrium fluctuations of the configurational parts of pressure and energy are found in the Lennard-Jones liquid and other simple liquids, but not in hydrogen-bonding liquids like methanol and water. The correlations, that are present also in the crystal and glass phases, reflect an effective inverse power-law repulsive potential dominating fluctuations, even at zero and slightly negative pressure. In experimental data for supercritical Argon, the correlations are found to be approximately 96%. Consequences for viscous liquid dynamics are discussed.Comment: Phys. Rev. Lett., in pres

Low State, Phase-Resolved IR Spectroscopy of VV Puppis

We present phase-resolved low resolution $JHK$ and higher resolution $K$-band spectroscopy of the polar VV Pup. All observations were obtained when VV Pup was in a low accretion state having a K magnitude near 15. The low resolution observations reveal cyclotron emission in the $J$ band during some phases, consistent with an origin near the active 30.5 MG pole on the white dwarf. The secondary in VV Pup appears to be a normal M7V star and we find that the $H$ and $K$ band fluxes are entirely due to this star at all orbital phases during the low accretion state. We use our higher resolution Keck spectroscopy to produce the first $K$-band radial velocity curve for VV Pup. Our orbital solution yields $K_2$=414$\pm27$ km sec$^{-1}$ and leads to mass estimates of M$_1$=0.73$\pm$0.05 M$_{\odot}$ and M$_2$=0.10$\pm$0.02 M$_{\odot}$. We find that the mass accretion rates during the normal low states of the polars VV Pup, EF Eri, and EQ Cet are near 10$^{-13}$ M$_{\odot}$ yr$^{-1}$. The fact that \.M is not zero in low state polars indicates active secondary stars in these binary systems, including the sub-stellar donor star present in EF Eri.Comment: Accepted in Astronomical Journal 5 figure

Longitudinal study of trachomatous trichiasis in The Gambia: barriers to acceptance of surgery.

PURPOSE: Investigation of compliance with surgery for trachomatous trichiasis has become a priority of the World Health Organization. This study was conducted to investigate attitudes toward trichiasis and its treatment and to determine the rate of surgical uptake in The Gambia. METHODS: A 1-year longitudinal study was performed in 190 subjects with trichiasis. Persons with major trichiasis (involving five lashes or more) were referred for surgery, and those with minor trichiasis were advised to epilate. Outcome measures included attitudes toward trichiasis and its treatment, reported barriers to surgical uptake, acceptance rates for surgery, and factors affecting acceptance. RESULTS: Twenty-three percent (95% confidence interval [CI] 16.5%-30.6%) of subjects with major trichiasis attended for surgery during the year. Degree of ignorance about surgery, symptoms impeding work, and a multiple income source for the head of household predicted attendance. Reported lack of time predicted nonattendance. Sixty-eight percent of patients who had undergone surgery were trichiasis free at last follow-up. CONCLUSIONS: Poor attendance for surgery remains a problem in The Gambia. Barriers include ignorance and lack of time and money. Health education and surgical delivery strategies are needed to overcome these barriers. Regular audit of surgical results is necessary, with retraining where indicated

Automated synthesis of PET radiotracers by copperâ mediated 18Fâ fluorination of organoborons: Importance of the order of addition and competing protodeborylation

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/142980/1/jlcr3583_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/142980/2/jlcr3583.pd