421 research outputs found

    DO SPORTFISH CONSUMPTION ADVISORIES AFFECT RESERVOIR ANGLERS' SITE CHOICE?

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    Increasing numbers of freshwater ecosystems have had sportfish consumption advisories posted in recent years. Advisories are sometimes issued in lieu of environmental remediation if they are considered more cost-effective than "cleaning up" the resource, but this approach assumes that anglers adjust behavior in response to the warning. Previous studies, however, suggest that compliance with advisories can be quite low. In contrast, this study measures a statistically significant response by reservoir anglers to consumption advisories. In particular, anglers are less likely to choose to visit a reservoir with an advisory than a similar reservoir without an advisory. Furthermore, the economic losses due to advisories are quantified for anglers in two regions of Tennessee.Resource /Energy Economics and Policy,

    Nonmarket valuation of the University of Tennessee Arboretum

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    Many studies have estimated demand functions for visits to recreation sites. Several included commonly defined recreation-based areas such as beaches, parks, lakes and rivers but excluded examination of horticulturally significant sites such as botanic gardens and arboreta. This study estimates user-demand and consumer surplus for visits to the University of Tennessee Arboretum by the travel cost method using maximum likelihood estimation techniques. Results suggest that travel cost and income of consumers are important determinants of demand, at least in the case of visits to the University of Tennessee Arboretum, and that consumer-use value may be derived from this demand

    Artificial evolution with Binary Decision Diagrams: a study in evolvability in neutral spaces

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    This thesis develops a new approach to evolving Binary Decision Diagrams, and uses it to study evolvability issues. For reasons that are not yet fully understood, current approaches to artificial evolution fail to exhibit the evolvability so readily exhibited in nature. To be able to apply evolvability to artificial evolution the field must first understand and characterise it; this will then lead to systems which are much more capable than they are currently. An experimental approach is taken. Carefully crafted, controlled experiments elucidate the mechanisms and properties that facilitate evolvability, focusing on the roles and interplay between neutrality, modularity, gradualism, robustness and diversity. Evolvability is found to emerge under gradual evolution as a biased distribution of functionality within the genotype-phenotype map, which serves to direct phenotypic variation. Neutrality facilitates fitness-conserving exploration, completely alleviating local optima. Population diversity, in conjunction with neutrality, is shown to facilitate the evolution of evolvability. The search is robust, scalable, and insensitive to the absence of initial diversity. The thesis concludes that gradual evolution in a search space that is free of local optima by way of neutrality can be a viable alternative to problematic evolution on multi-modal landscapes

    Early pubertal onset and its relationship with sexual risk taking, substance use and anti-social behaviour: a preliminary cross-sectional study

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    <p>Abstract</p> <p>Background</p> <p>In many countries age at pubertal onset has declined substantially. Relatively little attention has been paid to how this decline may affect adolescent behaviours such as substance use, violence and unprotected sex and consequently impact on public health.</p> <p>Methods</p> <p>In the UK, two opportunistic samples (aged 16-45 years), paper-based (n = 976) and online (n = 1117), examined factors associated with earlier pubertal onset and whether earlier age of onset predicted sexual risk-taking, substance use and anti-social behaviours during early adolescence.</p> <p>Results</p> <p>Overall, 45.6% of females reported menarche ≤ 12 years and 53.3% of males were categorised as having pubertal onset ≤ 11 years. For both sexes earlier pubertal onset was associated with poorer parental socio-economic status. Other pre-pubertal predictors of early onset were being overweight, more childhood illnesses (females) and younger age at time of survey (males). For both sexes earlier puberty predicted having drunk alcohol, been drunk, smoked and used drugs <14 years as well as having a sexual debut and unprotected sex <16 years. Males with earlier pubertal onset were more likely to report fighting and aggressive responses to emotional upset during early adolescence while females were more likely to report being bullied and having taken more time off school.</p> <p>Conclusion</p> <p>Results provide sufficient evidence for changes in age of pubertal onset to be further explored as a potential influence on trends in adolescent risk behaviours. Further insight into the relationship between early puberty and both obesity and socio-economic status may help inform early interventions to tackle the development of risk behaviours and health inequalities during early adolescence.</p

    Compressor Controls

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    Discussion GroupSurge Detection Logic - Trip or not on Surge Detection? Compressor Control Redundancy Requirements Is the primary purpose of an anti-surge valve a control or protection? Check valve locations and their impact on controllability Fallback Strategies of surge control flow transmitter failure Suction throttling experience - Inside or outside of the recycle loop Cost vs Benefit of implementing load sharing Controls Obsolescenc

    The UK quality and outcomes framework pay-for-performance scheme and spirometry: rewarding quality or just quantity? A cross-sectional study in Rotherham, UK

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    Background: Accurate spirometry is important in the management of COPD. The UK Quality and Outcomes Framework pay-for-performance scheme for general practitioners includes spirometry related indicators within its COPD domain. It is not known whether high achievement against QOF spirometry indicators is associated with spirometry to BTS standards. Methods: Data were obtained from the records of 3,217 patients randomly sampled from 5,649 patients with COPD in 38 general practices in Rotherham, UK. Severity of airflow obstruction was categorised by FEV1 (% predicted) according to NICE guidelines. This was compared with clinician recorded COPD severity. The proportion of patients whose spirometry met BTS standards was calculated in each practice using a random sub-sample of 761 patients. The Spearman rank correlation between practice level QOF spirometry achievement and performance against BTS spirometry standards was calculated. Results: Spirometry as assessed by clinical records was to BTS standards in 31% of cases (range at practice level 0% to 74%). The categorisation of airflow obstruction according to the most recent spirometry results did not agree well with the clinical categorisation of COPD recorded in the notes (Cohen's kappa = 0.34, 0.30 - 0.38). 12% of patients on COPD registers had FEV1 (% predicted) results recorded that did not support the diagnosis of COPD. There was no association between quality, as measured by adherence to BTS spirometry standards, and either QOF COPD9 achievement (Spearman's rho = -0.11), or QOF COPD10 achievement (rho = 0.01). Conclusion: The UK Quality and Outcomes Framework currently assesses the quantity, but not the quality of spirometry

    Chronic type B dissecting aortoiliac aneurysm repair complicated by congenital pelvic kidney

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    Although the association between abdominal aortic aneurysm and pelvic kidney is rare, previous reports have described various methods of repair with successful preservation of pelvic kidney function. We describe a unique case complicated by aortic dissection. Successful intra-operative perfusion of the kidney was maintained via a temporary axillorenal shunt
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