Homogenization of an ensemble of interacting resonant scatterers

We study theoretically the concept of homogenization in optics using an ensemble of randomly distributed resonant stationary atoms with density $\rho$. The ensemble is dense enough for the usual condition for homogenization, viz. $\rho\lambda^3 \gg 1$, to be reached. Introducing the coherent and incoherent scattered powers, we define two criteria to define the homogenization regime. We find that when the excitation field is tuned in a broad frequency range around the resonance, none of the criteria for homogenization is fulfilled, meaning that the condition $\rho\lambda^3\gg 1$ is not sufficient to characterize the homogenized regime around the atomic resonance. We interpret these results as a consequence of the light-induced dipole-dipole interactions between the atoms, which implies a description of scattering in terms of collective modes rather than as a sequence of individual scattering events. Finally, we show that, although homogenization can never be reached for a dense ensemble of randomly positioned laser-cooled atoms around resonance, it becomes possible if one introduces spatial correlations in the positions of the atoms or non-radiative losses, such as would be the case for organic molecules or quantum dots coupled to a phonon bath.Comment: 9 pages, 5 figures. Corrected mistakes in reference

What health policy makers need to know about mismatches between public perceptions of disease risk, prevalence and severity: a national survey

Objectives: The aim of this study was to assess people’s perceptions of their personal risk, population prevalence and perceived severity in relation to three key health conditions (cancer, heart disease and hearing loss), gauge the size of any misperceptions, and identify correlates of such misperceptions. / Design: This study was a cross-sectional survey. / Study sample: A total of 10,401 adults representative of the UK population were participated in the study. / Results: Clear majorities of people incorrectly believe that they are at greater personal risk of cancer (>75%), that cancer is more prevalent in the population (>50%) and that cancer is more disabling (>65%), than either heart disease or hearing loss. In turn, people consistently regard their personal risk of hearing loss, the population prevalence of hearing loss and the severity of hearing loss as lower than either cancer or heart disease. Multiple regression analyses showed inconsistent patterns of relationships between people’s beliefs, sociodemographic characteristics and their health behaviours. / Conclusions: Accuracy in beliefs about cancer, heart disease and hearing loss is low, and the relationships between these beliefs, their potential antecedents and consequences are complex. Policy makers should ensure close adherence to evidence or risk-making decisions that are costly both in financial terms and in terms of suboptimal population subjective well-being

Effectiveness of UK provider financial incentives on quality of care: a systematic review

Background: Provider financial incentives are being increasingly adopted to help improve standards of care while promoting efficiency. / Aim: To review the UK evidence on whether provider financial incentives are an effective way of improving the quality of health care. / Design and setting: Systematic review of UK evidence, undertaken in accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) recommendations. / Method: MEDLINE and Embase databases were searched in August 2016. Original articles that assessed the relationship between UK provider financial incentives and a quantitative measure of quality of health care were included. Studies showing improvement for all measures of quality of care were defined as ‘positive’, those that were ‘intermediate’ showed improvement in some measures, and those classified as ‘negative’ showed a worsening of measures. Studies showing no effect were documented as such. Quality was assessed using the Downs and Black quality checklist. / Results: Of the 232 published articles identified by the systematic search, 28 were included. Of these, nine reported positive effects of incentives on quality of care, 16 reported intermediate effects, two reported no effect, and one reported a negative effect. Quality assessment scores for included articles ranged from 15 to 19, out of a maximum of 22 points. / Conclusion: The effects of UK provider financial incentives on healthcare quality are unclear. Owing to this uncertainty and their significant costs, use of them may be counterproductive to their goal of improving healthcare quality and efficiency. UK policymakers should be cautious when implementing these incentives — if used, they should be subject to careful long-term monitoring and evaluation. Further research is needed to assess whether provider financial incentives represent a cost-effective intervention to improve the quality of care delivered in the UK

The Repressors of mTORC1 Signaling, REDD1 and REDD2, Are Induced in Immobilized Rat Skeletal Muscle

Please view abstract in the attached PDF file

Early phase trials of novel hearing therapeutics: Avenues and opportunities

Novel hearing therapeutics are rapidly progressing along the innovation pathway and into the clinical trial domain. Because these trials are new to the hearing community, they come with challenges in terms of trial design, regulation and delivery. In this paper, we address the key scientific and operational issues and outline the opportunities for interdisciplinary and international collaboration these trials offer. Vital to the future successful implementation of these therapeutics is to evaluate their potential for adoption into healthcare systems, including consideration of their health economic value. This requires early engagement with all stakeholder groups along the hearing innovation pathway

Design parameters for a siphon system

DHI are interested in understanding a rather unusual water extraction system that is operated by a water supply company. Typically when water is extracted from the ground a well is dug and a pump is installed in the well to push the water to the surface where it enters a distribution system of pipes. Such a system may consist of a dozen or so wells each connected to a single collection pipe. The system that DHI wish to more fully understand consists of a series of ten wells connected to a single collection pipe. The difference in the mode of operation is that the system contains no pumps in the wells. The force to collect the water comes from placing the end of the collection pipe in a tank that is continuously pumped to keep it at approximately 0.5 bar below atmospheric pressure. In this way the water is drawn out of the wells by a siphon mechanism. Such a system appears cheaper o install with fewer pumps and water supplied in this manner costs roughly half the price of water from a standard pump system. How this multiple siphon system works and how it might be controlled were the general problems of interest to the study group