9,781 research outputs found

    Waves of Beauty

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    Physiological Effects of Chronic Copper Exposure to Rainbow Trout (\u3cem\u3eOncorhynchus Mykiss\u3c/em\u3e) in Hard and Soft Water: Evaluation of Chronic Indicators

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    Effects of chronic copper exposure on a suite of indicators were examined: acute toxicity, acclimation, growth, sprint performance, whole-body electrolytes, tissue residues, and gill copper binding characteristics. Juvenile rainbow trout were exposed for 30 d to waterborne copper in hard water (hardness = 120 μg/L as CaCO3, pH = 8.0, Cu = 20 and 60 μg/L) and soft water (hardness = 20 μg/L as CaCO3, pH = 7.2, Cu = 1 and 2 μg/L). Significant acclimation to the metal occurred only in fish exposed to 60 mg/L, as seen by an approx. twofold increase in 96-h LC50 (153 vs 91 μg Cu/L). Chronic copper exposure had little or no effect on survival, growth, or swimming performance in either water hardness, nor was there any initial whole-body electrolyte loss (Na+ and Cl-). The present data suggest that the availability of food (3% wet body weight/day, distributed as three 1% meals) prevented growth inhibition and initial ion losses that usually result from Cu exposure. Elevated metal burdens in the gills and livers of exposed fish were measures of chronic copper exposure but not of effect. Initial gill binding experiments revealed the necessity of using radiolabeled Cu (64Cu) to detect newly accumulated Cu against gill background levels. Using this method, we verified the presence of saturable Cu-binding sites in the gills of juvenile rainbow trout and were able to make estimates of copperbinding affinity (log Kgill=Cu) and capacity (Bmax). Furthermore, we showed that both chronic exposure to Cu and to low water calcium had important effects on the Cu-binding characteristics of the gills

    Constant gap length trees in products of thick Cantor sets

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    We show that products of sufficiently thick Cantor sets generate trees in the plane with constant distance between adjacent vertices. Moreover, we prove that the set of admissible gap lengths has non-empty interior. This builds on the authors' previous work on distance sets of products of Cantor sets of sufficient Newhouse thickness

    Prescribed projections and efficient coverings by curves in the plane

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    Davies efficient covering theorem states that an arbitrary measurable set WW in the plane can be covered by full lines so that the measure of the union of the lines has the same measure as WW. This result has an interesting dual formulation in the form of a prescribed projection theorem. In this paper, we formulate each of these results in a nonlinear setting and consider some applications. In particular, given a measurable set WW and a curve Γ={(t,f(t)):t[a,b]}\Gamma=\{(t,f(t)): t\in [a,b]\}, where ff is C1C^1 with strictly monotone derivative, we show that WW can be covered by translations of Γ\Gamma in such a way that the union of the translated curves has the same measure as WW. This is achieved by proving an equivalent prescribed generalized projection result, which relies on a Venetian blind construction

    Decrease in health-related quality of life associated with awareness of hepatitis C virus infection among people who inject drugs in Scotland

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    Chronic hepatitis C virus (HCV) infection can significantly reduce health-related quality of life (QoL), but it is not clear if reduction is associated with the infection or with being aware of one's infection status. Understanding the impact of a HCV diagnosis on QoL is essential to inform decision-making regarding screening/testing and treatment. Using a cross-sectional design, we assessed QoL in 2898 people who inject drugs (PWID), surveyed in Scotland during 2010 using EQ-5D. Multifactorial regression compared self-reported QoL between PWID who were (i) chronically HCV-infected and aware of their infected status, (ii) chronically HCV-infected but unaware, and (iii) not chronically infected. Median time since onset of injecting was 10years; not chronically infected PWID were younger and had shorter injecting careers than chronically infected PWID. Median EQ-5D was highest for the not chronically infected and the chronic/unaware groups (0.73) compared with the chronic/aware group (0.66). After adjustment for demographic and behavioural co-factors, QoL was significantly reduced in chronic/aware compared with chronic/unaware PWID (adjusted B=-0.09, p=0.005); there was no evidence for a difference in QoL between not chronically infected and chronic/unaware PWID (adjusted B=-0.03, p=0.13). Awareness of one's chronic HCV status was associated with reduced health-related QoL, but there was no evidence for further reduction attributable to chronic infection itself after adjusting for important covariate differences

    Student Recital

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