1,799 research outputs found

    Modelling the behaviour of nutrients in the coastal waters of Scotland - an update on inputs from Scottish aquaculture and their impact on eutrophication status

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    A previous study estimated that salmon farming contributed approximately 6% of Scotland's nitrogen-nutrient input to coastal waters, and 13% of phosphorus (based on 2001 production figures). However, in some areas of the west of Scotland with small freshwater catchment areas and low levels of human habitation, aquaculture inputs represented greater than 80% of the total. In 2002, FRS published results from an ecosystem modelling study involving a collaboration with the Institute for Marine Research, University of Hamburg, and the Macaulay Land Use Research Institute in Aberdeen, to assess the eutrophication impact of various nutrient inputs to Scottish waters. The results suggested that a 50% reduction in aquaculture salmon production would have only a small impact on water quality which would be undetectable against the background of natural variability due to climate variations. Estimating aquaculture nutrient discharge is a difficult task. The 2002 study was based on data relating to the consented biomass of fish at farm sites in sea lochs. Since then, new data have become available on the actual harvest of fish at all sites in Scotland. In this report, we re-assess the salmon production in Scotland in 2001 and the consequent nutrient discharge, and repeat the ecosystem model runs to estimate the impact of reduction scenarios on eutrophication status. The new data indicate that the previous study had overestimated salmon production and nutrient discharge by approximately 18% Scotland wide. Production and discharge at Shetland and in the Southern Hebrides had been under-estimated, whilst that in the Minches had been over-estimated. New runs of the ecosystem model show that the original conclusions on eutrophication impact were sound. A scenario of 50% reduction in salmon production produced regional changes in water quality which were less than 25% of the natural variability due to climate. New runs simulating a cessation of aquaculture showed that even this extreme reduction scenario produced changes in water quality that were less than half the natural variability

    The role of bone morphogenetic protein 7 in the pathophysiology and treatment of vascular calcification associated with chronic renal failure.

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    Vascular calcification (VC) is an important complication of chronic renal failure (CRF), and a risk factor for reduced survival. Osteoblast-like cells in the vessel wall derived from resident vascular smooth muscle cells (VSMC) are considered central to the pathogenesis of VC, which is exacerbated by mineral ion abnormalities inherent in renal osteodystrophy (ROD). Nevertheless, its aetiology is incompletely understood, and no effective therapies exist. Recently, CRF has been characterised as a state of Bone Morphogenetic Protein 7 (BMP7) deficiency, and animal studies have shown that administration of this renal morphogen is efficacious in treating several aspects of renal failure, including progressive renal fibrosis and ROD. The hypothesis of this thesis is that BMP7 deficiency contributes to the pathogenesis of VC, by facilitating the emergence of the osteoblast-like cell, and that exogenous BMP7 administration abrogates it by normalising VSMC behaviour. This hypothesis was tested in atherosclerotic Low Density Lipoprotein Receptor Null (ldlf/j) mice. Uraemia was superimposed surgically to generate VC. Animals received BMP7 or vehicle over 15 weeks. Untreated uraemic animals had increased VC on histological and chemical grounds, and demonstrated increased expression of the characteristic osteoblast protein osteocalcin was demonstrated in vascular tissues. Both changes were reversed by BMP7 administration. Uraemic animals were shown to have an adynamic form of ROD, also reversed by BMP7 administration, suggesting that normalisation of mineral ion abnormalities may underlie the benefits of BMP7 on VC in CRF. In addition, in vitro studies showed that BMP7 can act directly on vascular cells to reduce extracellular calcification under conducive conditions. Finally, in an appendix, preliminary data is presented showing that expression of LRP5, a protein involved in the control of normal bone mineralization, may be increased in Idlf1 animals, suggesting that consequences of this genotype may be important to VC pathogenesis in this model

    The systematic revision of Chaetanthera Ruiz & Pav., and the reinstatement of the genus Oriastrum Poepp. & Endl. (Asteraceae; Mutisieae)

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    Chaetanthera Ruiz & Pav. (30 species, 1 variety, 2 hybrid forms) and Oriastrum Poepp. & Endl. (18 species, 1 variety) are among the most species-rich Astereaceae genera of the Chilean Flora. Formerly combined under one name, the two genera have been extensively revised. Chaetanthera is found mainly in Chile, with one Peruvian species and several scattered populations of other species in Andean Argentina. Oriastrum inhabits the higher elevations of the Andes, spread over Chile, Argentina, Bolivia and Peru. Systematic studies focussing on morphological and anatomical variation of characters taken from habit, involucral bracts, and achenes, combined with palynological and genetic (nr DNA) information are used to circumscribe Chaetanthera with two subgenera – Chaetanthera subgenus Chaetanthera and Chaetanthera subgenus Tylloma (D.Don) Less., and reinstate Oriastrum with two subgenera – Oriastrum subgenus Oriastrum and Oriastrum subgenus Egania (J.Rémy) A.M.R. Davies. Character variation is discussed in the context of form, function and habitat, with emphasis on the evolutionary adaptiveness of character traits seen in the two allied genera. Chaetanthera appears to show primary adaptation to cold and several secondary adaptations to arid conditions, typical of modern Chilean landscapes. Oriastrum taxa appear well-adapted to the cold, high elevations of the Andes, and show secondary developments trending towards an insular syndrome. The collated bio-geographical information of the taxa is considered in terms of endemism, hotspots and species radiations. Chaetanthera taxa have 2 loci of diversity hotspots in Chile – in Coquimbo and in Santiago. Trichome diversity and capitula morphology trends are used as evidence of species radiations in Chaetanthera. Oriastrum taxa are notable for parallel radiations of morphologically similar species within particular Andean zones: i.e., Altoandino or Altiplano. Case studies concerning three groups of Chaetanthera taxa are presented. The first case highlights the effect of the El Niño on the polymorphic C. glabrata along the Chilean Pacific coast. The second case deals with current active hybridisation between C. linearis and C. albiflora in the semi-arid Andean foothills. In the last example, incipient speciation and polymorphism between C. chilensis and C. elegans in southern Central Chile is discussed. Various statistical techniques for the analysis of hybridisation events are applied. All taxa are keyed out and described. Novel taxa are described and imaged or illustrated. Nomenclatural issues and lectotypification of 15 Chaetanthera names and 6 Oriastrum names are effected. Chaetanthera is described here with one novel species (C. pubescens A.M.R. Davies), one novel variety (C. glandulosa var. microphylla A.M.R. Davies), a new name (C. frayjorgensis A.M.R. Davies), and three new combinations: C. albiflora (Phil.) A.M.R. Davies, C. depauperata (Hook. & Arn.) A.M.R. Davies, C. taltalensis (Cabrera) A.M.R. Davies. Oriastrum is described here with four new species and one new variety: O. werdermannii A.M.R. Davies, O. famatinae A.M.R. Davies, O. tarapacensis A.M.R. Davies, O. tontalensis A.M.R. Davies and O. stuebelii var. cryptum A.M.R. Davies respectively. Five novel combinations are presented: O. abbreviatum (Cabrera) A.M.R. Davies, O. achenohirsutum (Tombesi) A.M.R. Davies, O. apiculatum (J.Rémy) A.M.R. Davies, O. revolutum (Phil.) A.M.R. Davies and O. stuebelii (Hieron.) A.M.R. Davies var. stuebelii

    Effect of waves on the tidal energy resource at a planned tidal stream array

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    Wave�current interaction (WCI) processes can potentially alter tidal currents, and consequently affect the tidal stream resource at wave exposed sites. In this research, a high resolution coupled wave-tide model of a proposed tidal stream array has been developed. We investigated the effect of WCI processes on the tidal resource of the site for typical dominant wave scenarios of the region. We have implemented a simplified method to include the effect of waves on bottom friction. The results show that as a consequence of the combined effects of the wave radiation stresses and enhanced bottom friction, the tidal energy resource can be reduced by up to 20% and 15%, for extreme and mean winter wave scenarios, respectively. Whilst this study assessed the impact for a site relatively exposed to waves, the magnitude of this effect is variable depending on the wave climate of a region, and is expected to be different, particularly, in sites which are more exposed to waves. Such effects can be investigated in detail in future studies using a similar procedure to that presented here. It was also shown that the wind generated currents due to wind shear stress can alter the distribution of this effect

    The quantum information manifold for epsilon-bounded forms

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    Let H be a self-adjoint operator bounded below by 1, and let V be a small form perturbation such that RVS has finite norm, where R is the resolvent at zero to the power 1/2 +epsilon, and S is the resolvent to the power 1/2-epsilon. Here, epsilon lies between 0 and 1/2. If the Gibbs state defined by H is sufficiently regular, we show that the free energy is an analytic function of V in the sense of Frechet, and that the family of density operators defined in this way is an analytic manifold modelled on a Banach space.Comment: 12 pages, report to Torun Conference, 199

    Non-exercise equations to estimate fitness in white European and South Asian men

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    Cardiorespiratory fitness is a strong, independent predictor of health, whether it is measured in an exercise test or estimated in an equation. The purpose of this study was to develop and validate equations to estimate fitness in middle-aged white European and South Asian men.Multiple linear regression models (n=168, including 83 white European and 85 South Asian men) were created using variables that are thought to be important in predicting fitness (VO2 max, mL⋅kg⋅min): age (years); BMI (kg·m); resting heart rate (beats⋅min); smoking status (0=never smoked, 1=ex or current smoker); physical activity expressed as quintiles (0=quintile 1, 1=quintile 2, 2=quintile 3, 3=quintile 4, 4=quintile 5), categories of moderate- to vigorous-intensity physical activity (0=<75 min⋅wk, 1=75-150 min⋅wk, 2=>150-225 min⋅wk, 3=>225-300 min⋅wk, 4=>300 min⋅wk), or minutes of moderate- to vigorous-intensity physical activity (min⋅wk); and, ethnicity (0=South Asian, 1=white). The leave-one-out-cross-validation procedure was used to assess the generalizability and the bootstrap and jackknife resampling techniques were used to estimate the variance and bias of the models.Around 70% of the variance in fitness was explained in models with an ethnicity variable, such as: VO2 max = 77.409 - (age*0.374) - (BMI*0.906) - (ex or current smoker*1.976) + (physical activity quintile coefficient) - (resting heart rate*0.066) + (white ethnicity*8.032), where physical activity quintile 1 is 1, 2 is 1.127, 3 is 1.869, 4 is 3.793, and 5 is 3.029. Only around 50% of the variance was explained in models without an ethnicity variable. All models with an ethnicity variable were generalizable and had low variance and bias.These data demonstrate the importance of incorporating ethnicity in non-exercise equations to estimate cardiorespiratory fitness in multi-ethnic populations

    Compression ultrasonography for false femoral artery aneurysms: Hypocoagulability is a cause of failure

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    Objectives:false femoral artery aneurysm is an occasional complication of percutaneous cardiovascular radiological procedures. Compression ultrasonography causes thrombosis non-invasively, reducing need for operative intervention. The technique fails in a proportion of cases. Analysis was undertaken to identify causes of failure.Design:prospective open study.Materials and Methods:patients presenting with false femoral artery aneurysm since 1984 were identified from a computerised database (BIPAS). Since 1993 compression ultrasonography has been performed as first line treatment according to a standard protocol. Prospectively collected ultrasonographic data and case notes were reviewed to identify causes of failed compression.Results:false femoral artery aneurysm occurred as a complication in 32/26 687 (0.12%) cardiovascular radiological procedures. Eighteen aneurysms were treated by compression. The technique was successful in 11/18 (61%) cases but primary failure occurred in seven cases. Six out of seven had bleeding abnormalities (Chi-squared analysis with Yates correction 10.55, p=0.0012), four were anticoagulated and compression was subsequently successful following reversal of warfarin therapy in three of these patients. In 4/18 cases surgical repair was necessary.Conclusions:compression ultrasonography is an effective treatment of false femoral aneurysms, however, hypocoagulability is a significant cause of failure. For patients in whom anticoagulation cannot be reversed, primary surgical repair should be considered

    Geometric and thermodynamic properties in Gauss-Bonnet gravity

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    In this paper, the generalized second law (GSL) of thermodynamics and entropy is revisited in the context of cosmological models in Gauss-Bonnet gravity with the boundary of the universe is assumed to be enclosed by the dynamical apparent horizon. The model is best fitted with the observational data for distance modulus. The best fitted geometric and thermodynamic parameters such as equation of state parameter, deceleration parameter and entropy are derived. To link between thermodynamic and geometric parameters, the "entropy rate of change multiplied by the temperature" as a model independent thermodynamic state parameter is also derived. The results show that the model is in good agreement with the observational analysis.Comment: 13 pages, 13 figures, to be published in Astrophysics and Space Sc

    Generalized Second Law of Thermodynamics in Quintom Dominated Universe

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    In this paper we will investigate the validity of the Generalized Second Law of thermodynamics for the Quintom model of dark energy. Reviewing briefly the quintom scenario of dark energy, we will study the conditions of validity of the generalized second law of thermodynamics in three cases: quintessence dominated, phantom dominated and transition from quintessence to phantom will be discussed.Comment: 8 pages, no figure
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