73 research outputs found

    Performance of the Bowen ratio systems on a 22 deg slope

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    The Bowen ratio energy balance technique was used to assess the energy fluxes on inclined surfaces during the First ISLSCP Field Experiment (FIFE). Since air flow over sloping surface may differ from that over flat terrain, it is important to examine whether Bowen ratio measurements taken on sloping surfaces are valid. In this study, the suitability of using the Bowen ratio technique on sloping surfaces was tested by examining the assumptions that the technique requires for valid measurements. This was accomplished by studying the variation of Bowen ratio measurements along a selected slope at the FIFE site. In September 1988, four Bowen ratio systems were set up in a line along the 22 degree north-facing slope with northerly air flow (wind went up the slope). In July of 1989, six Bowen ratio systems were similarly installed with southerly air flow (the wind went down slope). Results indicated that, at distances between 10 to 40 meters from the top of the slope, no temperature or vapor pressure gradient parallel to the slope was detected. Uniform Bowen ratio values were obtained on the slope, and thus the sensible or latent heat flux should be similar along the slope. This indicates that the assumptions for valid flux measurements are reasonably met at the slope. The Bowen ratio technique should give the best estimates of the energy fluxes on slopes similar to that in this study

    Comparison of ground and satellite based measurements of the fraction of photosynthetically active radiation intercepted by tall-grass prairie

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    The fraction, of photosynthetically active radiation absorbed by vegetation, F sub ipar, is an important requirement for estimating vegetation biomass productivity and related quantities. This was an integral part of a large international effort; the First ISLSCP Field Experiment (FIFE). The main objective of FIFE was to study the effects of vegetation on the land atmosphere interactions and to determine if these interactions can be assessed from satellite spectral measurements. The specific purpose of this experiment was to find out how well measurements of F sub ipar relate to ground, helicopter, and satellite based spectral reflectance measurements. Concurrent measurements of F sub ipar and ground, helicopter, and satellite based measurements were taken at 13 tall grass prairie sites in Kansas. The sites were subjected to various combinations of burning and grazing managements

    The relationship between serum zinc levels and myopia

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    Clinical significance: Myopia is inherently associated with eye growth and thereby possibly amenable to nutritional influence. However, little attention has been given to possible die- tary influences. This study demonstrates that serum zinc does not play a role in myopia development. Background: Myopia is inherently associated with eye growth and thereby possibly amena- ble to nutritional influence. A number of Asian studies have reported lower levels of serum zinc in myopic children. This study was designed to assess the relationship between serum zinc and myopia in the Korean population – using a subsample of participants from nation- ally representative data

    MOSAIC Clinical Trial Statistical Analysis Plan Primary Analysis v1.2

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    The Myopia Outcome Study of Atropine Treatment in Children (MOSAIC) is an investigator-led, double-masked randomised controlled trial of nightly atropine 0.01% eye drops compared to nightly placebo eye drops. A previously published protocol paper outlines the rationale, objective and sample size calculation for the study.1 A total of 250 participants were enrolled in the study and were randomised 2:1 to active treatment and placebo, respectively. This document outlines the plan for analysis of the 24-month outcomes of the MOSAIC

    Will treating progressive myopia overwhelm the eye care workforce? A workforce modelling study

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    Purpose Treatments for myopia progression are now available, but implementing these into clinical practice will place a burden on the eye care workforce. This study estimated the full-time equivalent (FTE) workforce required to implement myopia control treatments in the UK and Ireland. Methods To estimate the number of 6- to 21-year-olds with myopia, two models utilising separate data sources were developed. The examination-based model used: (1) the number of primary care eye examinations conducted annually and (2) the proportion of these that are for myopic young people. The prevalence-based model used epidemiological data on the age-specific prevalence of myopia. The proportion of myopic young people progressing ≥0.25 dioptres (D)/year or ≥0.50 D/year was obtained from Irish electronic health records and the recommended review schedule from clinical management guidelines. Results Using the examination and prevalence models, respectively, the estimated number of young people with myopia was 2,469,943 and 2,235,713. The extra workforce required to provide comprehensive myopia management for this target population was estimated at 226–317 FTE at the 0.50 D/year threshold and 433–630 FTE at the 0.25 D/year threshold. Extra visits required for myopia control treatment represented approximately 2.6% of current primary eye care examinations versus 13.6% of hospital examinations. Conclusions Implementing new myopia control treatments in primary care settings over the medium-term is unlikely to overwhelm the eye care workforce completely. Further increases to workforce, upskilling of current workforce and tools to reduce chair time will help to ensure sustainability of the eye care workforce into the future

    Novel Myopia Genes and Pathways Identified From Syndromic Forms of Myopia

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    Clinical phenotypes and syndromes that have refractive errors as a recognized feature were identified using the Online Mendelian Inheritance in Man (OMIM) database. One hundred fifty-four unique causative genes were identified, of which 119 were specifically linked with myopia and 114 represented syndromic myopia (i.e., myopia and at least one other clinical feature). Myopia was the only refractive error listed for 98 genes and hyperopia and the only refractive error noted for 28 genes, with the remaining 28 genes linked to phenotypes with multiple forms of refractive error. Pathway analysis was carried out to find biological processes overrepresented within these sets of genes. Genetic variants located within 50 kb of the 119 myopia-related genes were evaluated for involvement in refractive error by analysis of summary statistics from genome-wide association studies (GWAS) conducted by the CREAM Consortium and 23andMe, using both single-marker and gene-based tests

    Editorial: International Myopia Institute White Paper Series 2023

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    Honeybee linguistics—a comparative analysis of the waggle dance among species of Apis

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    All honeybees use the waggle dance to recruit nestmates. Studies on the dance precision of Apis mellifera have shown that the dance is often imprecise. Two hypotheses have been put forward aimed at explaining this imprecision. The first argues that imprecision in the context of foraging is adaptive as it ensures that the dance advertises the same patch size irrespective of distance. The second argues that the bees are constrained in their ability to be more precise, especially when the source is nearby. Recent studies have found support for the latter hypothesis but not for the “tuned-error” hypothesis, as the adaptive hypothesis became known. Here we investigate intra-dance variation among Apis species. We analyse the dance precision of A. florea, A. dorsata, and A. mellifera in the context of foraging and swarming. A. mellifera performs forage dances in the dark, using gravity as point of reference, and in the light when dancing for nest sites, using the sun as point of reference. Both A. dorsata and A. florea are open-nesting species; they do not use a different point of reference depending on context. A. florea differs from both A. mellifera and A. dorsata in that it dances on a horizontal surface and does not use gravity but instead “points” directly toward the goal when indicating direction. Previous work on A. mellifera has suggested that differences in dance orientation and point of reference can affect dance precision. We find that all three species improve dance precision with increasing waggle phase duration, irrespective of differences in dance orientation, and point of reference. When dancing for sources nearby, dances are highly variable. When the distance increases, dance precision converges. The exception is dances performed by A. mellifera on swarms. Here, dance precision decreases as the distance increases. We also show that the size of the patch advertised increases with increasing distance, contrary to what is predicted under the tuned-error hypothesis
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