29,648 research outputs found

    Incentives for breastfeeding and for smoking cessation in pregnancy: An exploration of types and meanings

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    Financial or tangible incentives are a strategy for improving health behaviours. The mechanisms of action of incentives are complex and debated. Using a multidisciplinary integrated mixed methods study, with service-user collaboration throughout, we developed a typology of incentives and their meanings for initiating and sustaining smoking cessation in pregnancy and breastfeeding. The ultimate aim was to inform incentive intervention design by providing insights into incentive acceptability and mechanisms of action. Systematic evidence syntheses of incentive intervention studies for smoking cessation in pregnancy or breastfeeding identified incentive characteristics, which were developed into initial categories. Little published qualitative data on user perspectives and acceptability was available. Qualitative interviews and focus groups conducted in three UK regions with a diverse socio-demographic sample of 88 women and significant others from the target population, 53 service providers, 24 experts/decision makers, and conference attendees identified new potential incentives and providers, with and without experience of incentives. Identified incentives (published and emergent) were classified into eight categories: cash and shopping vouchers, maternal wellbeing, baby and pregnancy-related, behaviour-related, health-related, general utility, awards and certificates, and experiences. A typology was refined iteratively through concurrent data collection and thematic analysis to explore participants' understandings of ‘incentives’ and to compare and contrast meanings across types. Our typology can be understood in three dimensions: the degree of restriction, the extent to which each is hedonic and/or utilitarian, and whether each has solely monetary value versus monetary with added social value. The layers of autonomy, meanings and the social value of incentive types influence their acceptability and interact with structural, social, and personal factors. Dimensions of incentive meaning that go beyond the simple incentive description should inform incentive programme design and are likely to influence outcomes

    Time outdoors and the prevention of myopia

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    Recent epidemiological evidence suggests that children who spend more time outdoors are less likely to be, or to become myopic, irrespective of how much near work they do, or whether their parents are myopic. It is currently uncertain if time outdoors also blocks progression of myopia. It has been suggested that the mechanism of the protective effect of time outdoors involves light-stimulated release of dopamine from the retina, since increased dopamine release appears to inhibit increased axial elongation, which is the structural basis of myopia. This hypothesis has been supported by animal experiments which have replicated the protective effects of bright light against the development of myopia under laboratory conditions, and have shown that the effect is, at least in part, mediated by dopamine, since the D2-dopamine antagonist spiperone reduces the protective effect. There are some inconsistencies in the evidence, most notably the limited inhibition by bright light under laboratory conditions of lens-induced myopia in monkeys, but other proposed mechanisms possibly associated with time outdoors such as relaxed accommodation, more uniform dioptric space, increased pupil constriction, exposure to UV light, changes in the spectral composition of visible light, or increased physical activity have little epidemiological or experimental support. Irrespective of the mechanisms involved, clinical trials are now underway to reduce the development of myopia in children by increasing the amount of time they spend outdoors. These trials would benefit from more precise definition of thresholds for protection in terms of intensity and duration of light exposures. These can be investigated in animal experiments in appropriate models, and can also be determined in epidemiological studies, although more precise measurement of exposures than those currently provided by questionnaires is desirable

    Testing equality of variances in the analysis of repeated measurements

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    The problem of comparing the precisions of two instruments using repeated measurements can be cast as an extension of the Pitman-Morgan problem of testing equality of variances of a bivariate normal distribution. Hawkins (1981) decomposes the hypothesis of equal variances in this model into two subhypotheses for which simple tests exist. For the overall hypothesis he proposes to combine the tests of the subhypotheses using Fisher's method and empirically compares the component tests and their combination with the likelihood ratio test. In this paper an attempt is made to resolve some discrepancies and puzzling conclusions in Hawkins's study and to propose simple modifications.\ud \ud The new tests are compared to the tests discussed by Hawkins and to each other both in terms of the finite sample power (estimated by Monte Carlo simulation) and theoretically in terms of asymptotic relative efficiencies

    Microlensing of the Lensed Quasar SDSS0924+0219

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    We analyze V, I and H band HST images and two seasons of R-band monitoring data for the gravitationally lensed quasar SDSS0924+0219. We clearly see that image D is a point-source image of the quasar at the center of its host galaxy. We can easily track the host galaxy of the quasar close to image D because microlensing has provided a natural coronograph that suppresses the flux of the quasar image by roughly an order of magnitude. We observe low amplitude, uncorrelated variability between the four quasar images due to microlensing, but no correlated variations that could be used to measure a time delay. Monte Carlo models of the microlensing variability provide estimates of the mean stellar mass in the lens galaxy (0.02 Msun < M < 1.0 Msun), the accretion disk size (the disk temperature is 5 x 10^4 K at 3.0 x 10^14 cm < rs < 1.4 x 10^15 cm), and the black hole mass (2.0 x 10^7 Msun < MBH \eta_{0.1}^{-1/2} (L/LE)^{1/2} < 3.3 x 10^8 Msun), all at 68% confidence. The black hole mass estimate based on microlensing is consistent with an estimate of MBH = 7.3 +- 2.4 x 10^7 Msun from the MgII emission line width. If we extrapolate the best-fitting light curve models into the future, we expect the the flux of images A and B to remain relatively stable and images C and D to brighten. In particular, we estimate that image D has a roughly 12% probability of brightening by a factor of two during the next year and a 45% probability of brightening by an order of magnitude over the next decade.Comment: v.2 incorporates referee's comments and corrects two errors in the original manuscript. 28 pages, 10 figures, published in Ap

    Exoplanetary atmosphere target selection in the era of comparative planetology

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    The large number of new planets expected from wide-area transit surveys means that follow-up transmission spectroscopy studies of their atmospheres will be limited by the availability of telescope assets. We argue that telescopes covering a broad range of apertures will be required, with even 1m-class instruments providing a potentially important contribution. Survey strategies that employ automated target selection will enable robust population studies. As part of such a strategy, we propose a decision metric to pair the best target to the most suitable telescope, and demonstrate its effectiveness even when only primary transit observables are available. Transmission spectroscopy target selection need not therefore be impeded by the bottle-neck of requiring prior follow-up observations to determine the planet mass. The decision metric can be easily deployed within a distributed heterogeneous network of telescopes equipped to undertake either broadband photometry or spectroscopy. We show how the metric can be used either to optimise the observing strategy for a given telescope (e.g. choice of filter) or to enable the selection of the best telescope to optimise the overall sample size. Our decision metric can also provide the basis for a selection function to help evaluate the statistical completeness of follow-up transmission spectroscopy datasets. Finally, we validate our metric by comparing its ranked set of targets against lists of planets that have had their atmospheres successfully probed, and against some existing prioritised exoplanet lists.Comment: 20 pages, 16 figures, 3 tables. Revision 3, accepted by MNRAS. Improvements include always using planetary masses where available and reliable, treatment for sky backgrounds and out-of-transit noise and a use case for defocused photometr

    Understanding environmental performance variation in manufacturing companies

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    Sustainability is an area of increasing interest for industry and its stakeholders, and some companies now aspire to address sustainability issues (e.g. carbon emissions) at strategic and operational levels. As companies are exploring the issues, they attempt to embed sustainability in their planning and management systems. It is at this point that the domains of environmental concern and performance management meet. The research questions explored in this paper are: What is the size of environmental performance variation? What are the challenges for sustainability performance management in practice?This work was funded by the EPSRC Centre for Innovative Manufacturing in Industrial Sustainability in Cambridge.This is the accepted version of the original article published by Emerald in the International Journal of Productivity and Performance Management. The original article is available online at http://www.emeraldinsight.com/journals.htm?articleid=17095236. This article is (c) Emerald Group Publishing and permission has been granted for this version to appear here (https://www.repository.cam.ac.uk/handle/1810/245026). Emerald does not grant permission for this article to be further copied/distributed or hosted elsewhere without the express permission from Emerald Group Publishing Limited
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