Deriving preference-based single indices from non-preference based condition-specific instruments: Converting AQLQ into EQ5D indices

Suppose that one has a clinical dataset with only non-preference-based QOL data, and that one nevertheless would like to perform a cost/QALY analysis. This study reports on some efforts to establish a "mapping" relationship between AQLQ (a non-preference-based QOL instrument for asthma) and EQ5D (a preference-based generic instrument). Various methods are described in terms of associated assumptions regarding the measurement properties of the instruments. This is followed by empirical mapping, based on regressing EQ5D on AQLQ. Six main regression models and two supplementary models are identified, and the regressions carried out. Performance of each model is explored in terms of goodness of fit between observed and predicted values, and of robustness of predictions on external data. The results show that it is possible to predict mean EQ5D indices given AQLQ data. The general implications for methods of mapping non-preference-based instruments onto preference-based measures are discussed

Deriving preference-based single indices from non-preference based condition-specific instruments: converting AQLQ into EQ5D indices

Suppose that one has a clinical dataset with only non-preference-based QOL data, and that one nevertheless would like to perform a cost/QALY analysis. This study reports on some efforts to establish a “mapping” relationship between AQLQ (a non-preference-based QOL instrument for asthma) and EQ5D (a preference-based generic instrument). Various methods are described in terms of associated assumptions regarding the measurement properties of the instruments. This is followed by empirical mapping, based on regressing EQ5D on AQLQ. Six main regression models and two supplementary models are identified, and the regressions carried out. Performance of each model is explored in terms of goodness of fit between observed and predicted values, and of robustness of predictions on external data. The results show that it is possible to predict mean EQ5D indices given AQLQ data. The general implications for methods of mapping non-preference-based instruments onto preference-based measures are discussed.EQ5D; AQLQ; mapping

On the origin of \gamma-ray emission in \eta\ Carina

\eta\ Car is the only colliding-wind binary for which high-energy \gamma\ rays are detected. Although the physical conditions in the shock region change on timescales of hours to days, the variability seen at GeV energies is weak and on significantly longer timescales. The \gamma-ray spectrum exhibits two features that can be interpreted as emission from the shocks on either side of the contact discontinuity. Here we report on the first time-dependent modelling of the non-thermal emission in \eta\ Car. We find that emission from primary electrons is likely not responsible for the \gamma-ray emission, but accelerated protons interacting with the dense wind material can explain the observations. In our model, efficient acceleration is required at both shocks, with the primary side acting as a hadron calorimeter, whilst on the companion side acceleration is limited by the flow time out of the system, resulting in changing acceleration conditions. The system therefore represents a unique laboratory for the exploration of hadronic particle acceleration in non-relativistic shocks.Comment: 5 pages, 4 figures, 1 table, accepted for publication in MNRAS Letter

Fluorides, orthodontics and demineralization: a systematic review

Objectives: To evaluate the effectiveness of fluoride in preventing white spot lesion (WSL) demineralization during orthodontic treatment and compare all modes of fluoride delivery. Data sources: The search strategy for the review was carried out according to the standard Cochrane systematic review methodology. The following databases were searched for RCTs or CCTs: Cochrane Clinical Trials Register, Cochrane Oral Health Group Specialized Trials Register, MEDLINE and EMBASE. Inclusion and exclusion criteria were applied when considering studies to be included. Authors of trials were contacted for further data. Data selection: The primary outcome of the review was the presence or absence of WSL by patient at the end of treatment. Secondary outcomes included any quantitative assessment of enamel mineral loss or lesion depth. Data extraction: Six reviewers independently, in duplicate, extracted data, including an assessment of the methodological quality of each trial. Data synthesis: Fifteen trials provided data for this review, although none fulfilled all the methodological quality assessment criteria. One study found that a daily NaF mouthrinse reduced the severity of demineralization surrounding an orthodontic appliance (lesion depth difference –70.0 µm; 95% CI –118.2 to –21.8 µm). One study found that use of a glass ionomer cement (GIC) for bracket bonding reduced the prevalence of WSL (Peto OR 0.35; 95% CI 0.15–0.84) compared with a composite resin. None of the studies fulfilled all of the methodological quality assessment criteria. Conclusions: There is some evidence that the use of a daily NaF mouthrinse or a GIC for bonding brackets might reduce the occurrence and severity of WSL during orthodontic treatment. More high quality, clinical research is required into the different modes of delivering fluoride to the orthodontic patient

The bactericidal activity of glutaraldehyde-impregnated polyurethane

Although glutaraldehyde is known to be bactericidal in solution, its potential use to create novel antibacterial polymers suitable for use in healthcare environments has not been evaluated. Here, novel materials were prepared in which glutaraldehyde was either incorporated into polyurethane using a simple “swell-encapsulation-shrink” method (hereafter referred to as “glutaraldehyde-impregnated polyurethane”), or simply applied to the polymer surface (hereafter referred to as “glutaraldehyde-coated polyurethane”). The antibacterial activity of glutaraldehyde-impregnated and glutaraldehyde-coated polyurethane samples was tested against Escherichia coli and Staphylococcus aureus. Glutaraldehyde-impregnated polyurethane resulted in a 99.9% reduction in the numbers of E. coli within 2 h and a similar reduction of S. aureus within 1 h, whereas only a minimal reduction in bacterial numbers was observed when the biocide was bound to the polymer surface. After 15 days, however, the bactericidal activity of the impregnated material was substantially reduced presumably due to polymerization of glutaraldehyde. Thus, although glutaraldehyde retains antibacterial activity when impregnated into polyurethane, activity is not maintained for extended periods of time. Future work should examine the potential of chemical modification of glutaraldehyde and/or polyurethane to improve the useful lifespan of this novel antibacterial polymer

Optical measurement of torque exerted on an elongated object by a non-circular laser beam

We have developed a scheme to measure the optical torque, exerted by a laser beam on a phase object, by measuring the orbital angular momentum of the transmitted beam. The experiment is a macroscopic simulation of a situation in optical tweezers, as orbital angular momentum has been widely used to apply torque to microscopic objects. A hologram designed to generate LG02 modes and a CCD camera are used to detect the orbital component of the beam. Experimental results agree with theoretical numerical calculations, and the strength of the orbital component suggest its usefulness in optical tweezers for micromanipulation.Comment: 6 pages, 7 figures, v2: minor typographical correction

Mesoscopic mechanism of exchange interaction in magnetic multilayers

We discuss a mesoscopic mechanism of exchange interaction in ferromagnet-normal metal-ferromagnet multilayers. We show that in the case when the metal's thickness is larger than the electron mean free path, the relative orientation of magnetizations in the ferromagnets is perpendicular. The exchange energy between ferromagnets decays with the metal thickness as a power law

Pressure-Induced Insulating State in Ba1-xRExIrO3 (RE = Gd, Eu) Single Crystals

BaIrO3 is a novel insulator with coexistent weak ferromagnetism, charge and spin density wave. Dilute RE doping for Ba induces a metallic state, whereas application of modest pressure readily restores an insulating state characterized by a three-order-of-magnitude increase of resistivity. Since pressure generally increases orbital overlap and broadens energy bands, a pressure-induced insulating state is not commonplace. The profoundly dissimilar responses of the ground state to light doping and low hydrostatic pressures signal an unusual, delicate interplay between structural and electronic degrees of freedom in BaIrO3