2,214 research outputs found

    Contribution of dissolved organic nitrogen from rivers to estuarine eutrophication

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    Signal crayfish burrowing, bank retreat and sediment supply to rivers: a biophysical sediment budget

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    Burrowing into riverbanks by animals transfers sediment directly into river channels and has been hypothesised to accelerate bank erosion and promote mass failure. A field monitoring study on two UK rivers invaded by signal crayfish (Pacifastacus leniusculus) assessed the impact of burrowing on bank erosion processes. Erosion pins were installed in 17 riverbanks across a gradient of crayfish burrow densities and monitored for 22 months. Bank retreat increased significantly with crayfish burrow density. At the bank scale (<6 m river length), high crayfish burrow densities were associated with accelerated bank retreat of up to 253% and more than a doubling of the area of bank collapse compared with banks without burrows. Direct sediment supply by burrowing activity contributed 0.2% and 0.6% of total sediment at the reach (1.1 km) and local bank (<6 m) scales. However, accelerated bank retreat caused by burrows contributed 12.2% and 29.8% of the total sediment supply at the reach and bank scales. Together, burrowing and the associated acceleration of retreat and collapse supplied an additional 25.4 t km−1 a−1 of floodplain sediments at one site, demonstrating the substantial impact that signal crayfish can have on fine sediment supply. For the first time, an empirical relation linking animal burrow characteristics to riverbank retreat is presented. The study adds to a small number of sediment budget studies that compare sediment fluxes driven by biotic and abiotic energy but is unique in isolating and measuring the substantial interactive effect of the acceleration of abiotic bank erosion facilitated by biotic activity. Biotic energy expended through burrowing represents an energy surcharge to the river system that can augment sediment erosion by geophysical mechanisms

    Quantifying beliefs regarding telehealth: Development of the Whole Systems Demonstrator Service User Technology Acceptability Questionnaire

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    Introduction: Telehealth (TH) is a potential solution to the increased incidence of chronic illness in an ageing population. The extent to which older people and users with chronic conditions accept and adhere to using assistive technologies is a potential barrier to mainstreaming the service. This study reports the development and validation of the Whole Systems Demonstrator (WSD) Service User Technology Acceptability Questionnaire (SUTAQ). / Methods: Questionnaires measuring the acceptability of TH, quality of life, well-being and psychological processes were completed by 478 users of TH. The 22 acceptability items were subject to principal components analysis (PCA) to determine sub-scales. Scale scores, relationships between scales and other patient-reported outcome measures (PROMs), and group differences on scales were utilised to check the reliability and validity of the measure. / Results: PCAs of SUTAQ items produced six TH acceptability scales: enhanced care, increased accessibility, privacy and discomfort, care personnel concerns, kit as substitution and satisfaction. Significant correlations within these beliefs and between these scales and additional PROMs were coherent, and the SUTAQ sub-scales were able to predict those more likely to refuse TH. / Discussion: The SUTAQ is an instrument that can be used to measure user beliefs about the acceptability of TH, and has the ability to discriminate between groups and predict individual differences in beliefs and behaviour. Measuring acceptability beliefs of TH users can provide valuable information to direct and target provision of services to increase uptake and maintain use of TH

    A Suborbital Payload for Soft X-ray Spectroscopy of Extended Sources

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    We present a suborbital rocket payload capable of performing soft X-ray spectroscopy on extended sources. The payload can reach resolutions of ~100(lambda/dlambda) over sources as large as 3.25 degrees in diameter in the 17-107 angstrom bandpass. This permits analysis of the overall energy balance of nearby supernova remnants and the detailed nature of the diffuse soft X-ray background. The main components of the instrument are: wire grid collimators, off-plane grating arrays and gaseous electron multiplier detectors. This payload is adaptable to longer duration orbital rockets given its comparatively simple pointing and telemetry requirements and an abundance of potential science targets.Comment: Accepted to Experimental Astronomy, 12 pages plus 1 table and 17 figure

    The Galaxy Structure-Redshift Relationship

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    There exists a gradual, but persistent, evolutionary effect in the galaxy population such that galaxy structure and morphology change with redshift. This galaxy structure-redshift relationship is such that an increasingly large fraction of all bright and massive galaxies at redshifts 2 < z < 3 are morphologically peculiar at wavelengths from rest-frame ultraviolet to rest-frame optical. There are however examples of morphologically selected spirals and ellipticals at all redshifts up to z ~ 3. At lower redshift, the bright galaxy population smoothly transforms into normal ellipticals and spirals. The rate of this transformation strongly depends on redshift, with the swiftest evolution occurring between 1 < z < 2. This review characterizes the galaxy structure-redshift relationship, discusses its various physical causes, and how these are revealing the mechanisms responsible for galaxy formation.Comment: 20 pages, 8 figures. Invited Review to appear in "Penetrating Bars Through Masks of Cosmic Dust: The Hubble Tuning Fork Strikes A New Note", ed. D. Block et a

    Echocardiographic detection of anomalous course of the left innominate vein

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    Anomalous course of the left innominate vein beneath the aortic arch is a rare congenital anomaly. We report the case of a 3 year old child in whom this defect was detected by two-dimensional and Doppler echocardiography. The echocardiographic appearance of the anomalous course of the left innominate vein is illustrated and the importance of identifying this rare systemic venous anomaly is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42535/1/10554_2005_Article_BF01784202.pd

    Pichinde virus induces microvascular endothelial cell permeability through the production of nitric oxide

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    This report is the first to demonstrate infection of human endothelial cells by Pichinde virus (PIC). PIC infection induces an upregulation of the inducible nitric oxide synthase gene; as well as an increase in detectable nitric oxide (NO). PIC induces an increase in permeability in endothelial cell monolayers which can be abrogated at all measured timepoints with the addition of a nitric oxide synthase inhibitor, indicating a role for NO in the alteration of endothelial barrier function. Because NO has shown antiviral activity against some viruses, viral titer was measured after addition of the NO synthase inhibitor and found to have no effect in altering virus load in infected EC. The NO synthase inhibition also has no effect on levels of activated caspases induced by PIC infection. Taken together, these data indicate NO production induced by Pichinde virus infection has a pathogenic effect on endothelial cell monolayer permeability

    Classification of Ventricular Septal Defects for the Eleventh Iteration of the International Classification of Diseases—Striving for Consensus: A Report From the International Society for Nomenclature of Paediatric and Congenital Heart Disease

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    The definition and classification of ventricular septal defects have been fraught with controversy. The International Society for Nomenclature of Paediatric and Congenital Heart Disease is a group of international specialists in pediatric cardiology, cardiac surgery, cardiac morphology, and cardiac pathology that has met annually for the past 9 years in an effort to unify by consensus the divergent approaches to describe ventricular septal defects. These efforts have culminated in acceptance of the classification system by the World Health Organization into the 11th Iteration of the International Classification of Diseases. The scheme to categorize a ventricular septal defect uses both its location and the structures along its borders, thereby bridging the two most popular and disparate classification approaches and providing a common language for describing each phenotype. Although the first-order terms are based on the geographic categories of central perimembranous, inlet, trabecular muscular, and outlet defects, inlet and outlet defects are further characterized by descriptors that incorporate the borders of the defect, namely the perimembranous, muscular, and juxta-arterial types. The Society recognizes that it is equally valid to classify these defects by geography or borders, so the emphasis in this system is on the second-order terms that incorporate both geography and borders to describe each phenotype. The unified terminology should help the medical community describe with better precision all types of ventricular septal defects

    Proactive and politically skilled professionals: What is the relationship with affective occupational commitment?

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    The aim of this study is to extend research on employee affective commitment in three ways: (1) instead of organizational commitment the focus is on occupational commitment; (2) the role of proactive personality on affective occupational commitment is examined; and (3) occupational satisfaction is examined as a mediator and political skills as moderator in the relationship between proactive personality and affective occupational commitment. Two connected studies, one in a hospital located in the private sector and one in a university located in the public sector, are carried out in Pakistan, drawing on a total sample of over 400 employees. The results show that proactive personality is positively related to affective occupational commitment, and that occupational satisfaction partly mediates the relationship between proactive personality and affective occupational commitment. No effect is found for a moderator effect of political skills in the relationship between proactive personality and affective occupational commitment. Political skills however moderate the relationship between proactive personality and affective organizational commitment
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