Energy of the Conduction Band in Near Critical Point Fluids

The study of the evolution of the conduction band in dense gases and supercritical fluids near the critical point has been complicated by a lack of precise experimental measurements. Both photoemission from an electrode immersed in the fluid and field ionization of a molecule doped into the fluid have been used to probe solvent density effects on the energy of an excess electron as a function of fluid number density and temperature. In this perspective, we present recent experimental results that show a strong critical point effect on the minimumconduction band energy near the critical density and temperature of a fluid.We also discuss the recent development of a new theoretical model that advances our understanding of the density and temperature dependence of the conduction band minimumin near critical point fluids

Energy of the quasi-free electron in argon, krypton and xenon

Abstract Recent field ionization measurements of various high-n molecular Rydberg states doped into argon, krypton and xenon perturbers are presented as a function of perturber number density up to the density of the triple point liquid. These data are modeled to within ±0.3% of experiment on both critical and noncritical isotherms using a new theoretical treatment that includes: (i) the polarization of the perturber by the dopant cation, (ii) the polarization of the perturber by the quasi-free electron that arises from field ionization of the dopant, and (iii) the kinetic energy of the quasi-free electron. The polarization terms are determined by a standard statistical mechanical treatment. However, the kinetic energy of the quasi-free electron is calculated within a new local Wigner-Seitz model that contains only one adjustable parameter. This treatment provides an accurate model of the energy of the bottom of the conduction band (V 0 ) in argon, krypton and xenon from the dilute gas up to the density of the triple point liquid, on both critical and noncritical isotherms. The use of supercritical fluids in environmental remediation, in the treatment of high-level hazardous wastes and in tailoring chemical reactions for specific product yields necessitates a better understanding of density and temperature effects on the properties of neutral and charged species solvated in these fluids. We have recently studied the perturber induced shift ∆ D (ρ P ) of dopant ionization energyand the quasi-free electron energy V 0 (ρ P ) -in the rare gases Ar [1-3], Kr Experimental information on the dopants and perturbers used in these studies and the procedures used to ensure homogeneous mixing of samples in the gas handling system have been described previously The quasi-free electron energy V 0 (ρ P ) in a dense perturbing gas can be extracted from ∆ D (ρ P ), which is determined from field ionization studies, using [1-5] where P + (ρ P ) is the ensemble average dopant ionic core/perturber polarization energy, and ρ P is the perturber number density. P + (ρ P ) is calculated from a standard statistical mechanical treatment via [1-5] In eq. (2) g PD (r) is the perturber/dopant radial distribution function, and w + (r) is the perturber/ion interaction potentia

Xenon low-n Rydberg states in supercritical argon near the critical point

Abstract We present vacuum ultraviolet absorption spectra and an asymmetric line shape simulation of the 6s and 6s Rydberg states (including the blue satellite bands) of xenon doped into argon, from low argon number density to the density of the triple point liquid, at both noncritical temperatures and near (+0.5 • C) the critical isotherm of argon (i.e., −122.3 • C). The argon induced shift in the simulated primary transition of the Xe 6s and 6s Rydberg states is presented as a function of argon number density for noncritical temperatures and along an isotherm near the critical temperature. This shift demonstrates a perturber critical point effect on the transition energies of low-n dopant Rydberg states

New Limits to the Infrared Background: Bounds on Radiative Neutrino Decay and on Contributions of Very Massive Objects to the Dark Matter Problem

From considering the effect of γ-γ interactions on recently observed TeV gamma-ray spectra, improved limits are set to the density of extragalactic infrared photons which are robust and essentially model independent. The resulting limits are more than an order of magnitude more restrictive than direct observations in the 0.025–0.3 eV regime. These limits are used to improve constraints on radiative neutrino decay in the mass range above 0.05 eV and to rule out very massive objects as providing the dark matter needed to explain galaxy rotation curves. Lower bounds on the maximum distance which TeV gamma rays may probe are also derived

Framework, principles and recommendations for utilising participatory methodologies in the co-creation and evaluation of public health interventions

Background: Due to the chronic disease burden on society, there is a need for preventive public health interventions to stimulate society towards a healthier lifestyle. To deal with the complex variability between individual lifestyles and settings, collaborating with end-users to develop interventions tailored to their unique circumstances has been suggested as a potential way to improve effectiveness and adherence. Co-creation of public health interventions using participatory methodologies has shown promise but lacks a framework to make this process systematic. The aim of this paper was to identify and set key principles and recommendations for systematically applying participatory methodologies to co-create and evaluate public health interventions. Methods: These principles and recommendations were derived using an iterative reflection process, combining key learning from published literature in addition to critical reflection on three case studies conducted by research groups in three European institutions, all of whom have expertise in co-creating public health interventions using different participatory methodologies. Results: Key principles and recommendations for using participatory methodologies in public health intervention co-creation are presented for the stages of: Planning (framing the aim of the study and identifying the appropriate sampling strategy); Conducting (defining the procedure, in addition to manifesting ownership); Evaluating (the process and the effectiveness) and Reporting (providing guidelines to report the findings). Three scaling models are proposed to demonstrate how to scale locally developed interventions to a population level. Conclusions: These recommendations aim to facilitate public health intervention co-creation and evaluation utilising participatory methodologies by ensuring the process is systematic and reproducible

Cost-Effectiveness of Alternative Models of Community Health Workers for promotion of Maternal, Newborn and Child Health in Northern Nigeria

Background: Community health workers (CHWs) have proven to be successful in mobilizing rural populations to utilize primary health services where they can be supported by skilled health workers. This study assessed the cost-effectiveness of three CHW models implemented in northern Nigeria. Method: Using a quasi-experimental design, we compare the costs and health outcomes for communities where CHW models were implemented versus those where no CHW models were implemented. The three CHW models were Community Volunteer (CV), Nigeria Subsidy Reinvestment and Empowerment Programme for Maternal and Child Health Village Health Worker (VHW), and the Junior Community Health Extension Worker providing community based service delivery (JCHEW-CBSD). The unit costs, consultation patterns, benefit-cost ratios, and cost-effectiveness ratios were calculated for the three CHW models. Results: Compared to the CVs, the VHWs and the JCHEW-CBSDs had the highest levels of interactions in the community, each helping to educate 120-130 pregnant women each year. JCHEW-CBSDs made the most referrals for antenatal care (220) and facility births (122); however, women who interacted with the VHWs increased their antenatal care visits the most, with 92% of the women having made at least one and 70% having made 4+ ANC visits. The unit cost of the CVs was lowest, compared to the other two models, at $127 versus$3176 for the VHW model and $4443 for the JCHEWCBSD model. The outcomes per unit cost ratios were highest for the VHW model. For every$1000 invested in the VHW, there were 54 ANC 4+ visits and 95.9 deliveries attended by a skilled birth attendant. The Incremental Cost-Effectiveness Ratios for the VHW model were also lower than for the JCHEW-CBSD model, ranging from a low of an additional $25 per incremental ANC visits to$152 for increments in attended deliveries, the latter amount three times lower than for the JCHEW-CBSD model. Conclusion: This cost-effectiveness study of CHW models in Northern Nigeria shows that the SURE-P VHW model was most cost-effective. The VHW model, an enhanced volunteer model, promises the greatest return on investment if scaled up in northern Nigeria and settings with similar health care delivery contexts

Searching for gravitational waves from known pulsars

We present upper limits on the amplitude of gravitational waves from 28 isolated pulsars using data from the second science run of LIGO. The results are also expressed as a constraint on the pulsars' equatorial ellipticities. We discuss a new way of presenting such ellipticity upper limits that takes account of the uncertainties of the pulsar moment of inertia. We also extend our previous method to search for known pulsars in binary systems, of which there are about 80 in the sensitive frequency range of LIGO and GEO 600.Comment: Accepted by CQG for the proceeding of GWDAW9, 7 pages, 2 figure