489 research outputs found

    An example application of the CEN Water quality — Guidance standard for assessing the hydromorphological features of rivers to the River Frome, Dorset, Southern England

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    This report documents a comprehensive application of the framework proposed in CEN Standard CEN/ TC 230/ WG 25/ EN14614 to the River Frome, Dorset, Southern England. Therefore, this report needs to be read with reference to that Standard. The framework was first developed in REFORM, a European Union Framework 7 project (Grant Agreement 282656), established to improve the success of hydromorphological restoration. The Standard determines the natural hydromorphological condition of rivers for many applications. It is appropriate for long-term, catchment-scale management, e.g. river basin planning and implementation. It is also able to support assessments for site-scale, project delivery, e.g. flood management schemes, channel maintenance and channel restoration. The hierarchical and multiscale nature of the analysis illustrated in this report provides causative links between catchment processes and local scale hydromorphological conditions; for example, how catchment scale issues influence fine sediment erosion, transfer and deposition. In this way it can facilitate the application of a DPSIR (Drivers, Pressures, State, Impact, Response) model of management intervention, illustrate causes and consequences, and help target sustainable management solutions

    Floating matter: a neglected component of the ecological integrity of rivers

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    Floating matter (FM) is a pivotal, albeit neglected, element along river corridors contributing to their ecological integrity. FM consists of particulate matter of natural (e.g. wood, branches, leaves, seeds) and anthropogenic (e.g. plastic, human waste) origin as well as of organisms that, due to its properties, is able to float on the water surface. In this paper, we provide a comprehensive overview of the FM cycle and the fundamental environmental functions FM provides along rivers. Indeed, FM serves as an important geomorphological agent, a dispersal vector for animals and plant propagules, a habitat, a resource, and a biogeochemical component. Furthermore, we collected data on the amount of FM accumulating at dams and in reservoirs, and related it to key characteristics of the respective catchments. River fragmentation truncates the natural dynamics of FM through its extraction at damming structures, alteration in the flow regime, and low morphological complexity, which may decrease FM retention. Finally, we identify key knowledge gaps in relation to the role FM plays in supporting river integrity, and briefly discuss FM management strategies. (c) 2019, Springer Nature Switzerland AG.This work has been carried out within the SMART Joint Doctorate Programme ‘Science for the MAnagement of Rivers and their Tidal systems’, funded by the Erasmus Mundus programme of the European Union (http://www.riverscience.it). We also acknowledge financial support through the Excellence Initiative at the University of Tübingen, funded by the German Federal Ministry of Education and Research (BMBF) and the German Research Foundation (DFG). OS is thankful for a partial support from IGB equal opportunity fund for young female scientists and DFG (SU 405/10-1). SDL has received funding from the European Union’s Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie Grant agreement no. 748625

    Advances in the Imaging of Pituitary Tumors

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    © 2020 Elsevier Inc. In most patients with pituitary adenomas magnetic resonance imaging (MRI) is essential to guide effective decision-making. T1- and T2-weighted sequences allow the majority of adenomas to be readily identified. Supplementary MR sequences (e.g. FLAIR; MR angiography) may also help inform surgery. However, in some patients MRI findings are ‘negative’ or equivocal (e.g. with failure to reliably identify a microadenoma or to distinguish postoperative change from residual/recurrent disease). Molecular imaging [e.g. 11C-methionine PET/CT coregistered with volumetric MRI (Met-PET/MRCR)] may allow accurate localisation of the site of de novo or persistent disease to guide definitive treatment (e.g. surgery or radiosurgery)

    Long‐term corticosteroid use, adrenal insufficiency and the need for steroid‐sparing treatment in adult severe asthma

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    Funder: AstraZeneca; Id: http://dx.doi.org/10.13039/100004325Abstract: Secondary adrenal insufficiency (AI) occurs as the result of any process that disrupts normal hypothalamic and/or anterior pituitary function and causes a decrease in the secretion of steroid hormones from the adrenal cortex. The most common cause of secondary AI is exogenous corticosteroid therapy administered at supraphysiologic dosages for ≥ 1 month. AI caused by oral corticosteroids (OCS) is not well‐recognized or commonly diagnosed but is often associated with reduced well‐being and can be life‐threatening in the event of an adrenal crisis. Corticosteroid use is common in respiratory diseases, and asthma is a representative condition that illustrates the potential challenges and opportunities related to corticosteroid‐sparing therapies. For individuals with severe asthma (approximately 5%–10% of all cases), reduction or elimination of maintenance OCS without loss of control can now be accomplished with biologic therapies targeting inflammatory mediators. However, the optimal strategy to ensure early identification and treatment of AI and safe OCS withdrawal in routine clinical practice remains to be defined. Many studies with biologics have involved short evaluation periods and small sample sizes; in addition, cautious approaches to OCS tapering in studies with a placebo arm, coupled with inconsistent monitoring for AI, have contributed to the lack of clarity. If the goal is to greatly reduce and, where possible, eliminate long‐term OCS use in severe asthma through the increasing adoption of biologic treatments, there is an urgent need for clinical trials that address both the speed of OCS withdrawal and how to monitor for AI

    Dynamic drag modeling of submerged aquatic vegetation canopy flows

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    Vegetation has a profound effect on flow and sediment transport processes in natural rivers, by increasing both skin friction and form drag. The increase in drag introduces a drag discontinuity between the in-canopy flow and the flow above, which leads to the development of an inflection point in the velocity profile, resembling a free shear layer. Therefore, drag acts as the primary driver for the entire canopy system. Most current numerical hydraulic models which incorporate vegetation rely either on simple, static plant forms, or canopy-scaled drag terms. However, it is suggested that these are insufficient as vegetation canopies represent complex, dynamic, porous blockages within the flow, which are subject to spatially and temporally dynamic drag forces. Here we present a dynamic drag methodology within a CFD framework. Preliminary results for a benchmark cylinder case highlight the accuracy of the method, and suggest its applicability to more complex cases
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