410 research outputs found

    Roy-Steiner equations for pion-nucleon scattering

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    Starting from hyperbolic dispersion relations, we derive a closed system of Roy-Steiner equations for pion-nucleon scattering that respects analyticity, unitarity, and crossing symmetry. We work out analytically all kernel functions and unitarity relations required for the lowest partial waves. In order to suppress the dependence on the high-energy regime we also consider once- and twice-subtracted versions of the equations, where we identify the subtraction constants with subthreshold parameters. Assuming Mandelstam analyticity we determine the maximal range of validity of these equations. As a first step towards the solution of the full system we cast the equations for the ππNˉN\pi\pi\to\bar NN partial waves into the form of a Muskhelishvili-Omn\`es problem with finite matching point, which we solve numerically in the single-channel approximation. We investigate in detail the role of individual contributions to our solutions and discuss some consequences for the spectral functions of the nucleon electromagnetic form factors.Comment: 106 pages, 18 figures; version published in JHE

    Physiological and Psychological Effects of Deception on Pacing Strategy and Performance: A Review

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    The aim of an optimal pacing strategy during exercise is to enhance performance whilst ensuring physiological limits are not surpassed, which has been shown to result in a metabolic reserve at the end of the exercise. There has been debate surrounding the theoretical models that have been proposed to explain how pace is regulated, with more recent research investigating a central control of exercise regulation. Deception has recently emerged as a common, practical approach to manipulate key variables during exercise. There are a number of ways in which deception interventions have been designed, each intending to gain particular insights into pacing behaviour and performance. Deception methodologies can be conceptualised according to a number of dimensions such as deception timing (prior to or during exercise), presentation frequency (blind, discontinuous or continuous) and type of deception (performance, biofeedback or environmental feedback). However, research evidence on the effects of deception has been perplexing and the use of complex designs and varied methodologies makes it difficult to draw any definitive conclusions about how pacing strategy and performance are affected by deception. This review examines existing research in the area of deception and pacing strategies, and provides a critical appraisal of the different methodological approaches used to date. It is hoped that this analysis will inform the direction and methodology of future investigations in this area by addressing the mechanisms through which deception impacts upon performance and by elucidating the potential application of deception techniques in training and competitive settings

    A Prominent Role for DC-SIGN+ Dendritic Cells in Initiation and Dissemination of Measles Virus Infection in Non-Human Primates

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    Measles virus (MV) is a highly contagious virus that is transmitted by aerosols. During systemic infection, CD150+T and B lymphocytes in blood and lymphoid tissues are the main cells infected by pathogenic MV. However, it is unclear which cell types are the primary targets for MV in the lungs and how the virus reaches the lymphoid tissues. In vitro studies have shown that dendritic cell (DC) C-type lectin DC-SIGN captures MV, leading to infection of DCs as well as transmission to lymphocytes. However, evidence of DC-SIGN-mediated transmission in vivo has not been established. Here we identified DC-SIGNhiDCs as first target cells in vivo and demonstrate that macaque DC-SIGN functions as an attachment receptor for MV. Notably, DC-SIGNhicells from macaque broncho-alveolar lavage and lymph nodes transmit MV to B lymphocytes, providing in vivo support for an important role for DCs in both initiation and dissemination of MV infection

    Die sesweke-ondersoek ná koronêre vatchirurgie: bevindinge by Bloemfontein Medi-Clinic Hospitaal

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    The six-week examination after coronary bypass surgery: findings at a Medi-Clinic Hospital in Bloemfontein. Background: Surgery provides symtomatic relief and improves the prognosis in patients with coronary artery disease. The general practitioner manages the postoperative patient. The aim of the study was to establish which symptoms and signs are present at the time of the six-week follow-up after coronary artery bypass graft surgery. Methods: A descriptive database search with a retrospective direction of enquiry was undertaken to establish the symptoms and signs experienced by patients six weeks after coronary artery bypass surgery (CABG). The patients were operated on by one surgeon in one hospital. The prevalence of readmissions, chest pain, angina, blood pressure, NYHA class, lung auscultation, wounds and medications were noted. Results: Records were available for 181 patients. However, only 158 patients were seen in the surgeon\'s rooms six weeks after surgery. Patients were also consulted before and after the six weeks, but usually in hospital. One patient died before her appointment and two patients did not return for follow-up. Fifteen (8.5%; 95% CI 4.9% to 13.7%) patients were readmitted to a hospital for a variety of reasons, Severe chest pain was present in 3.4% (95% CI 1.3% to 7.2%) patients. One patient had a myocardial infarction with patent grafts at cardiac catheterisation. Another two patients were investigated for possible angina, but it could not be proved. A total of 82.2% (95% CI 76.5% to 87.9%) of the patients were in NYHA I, whereas 3.5% (95% CI 1.3% to 7.4%) were class III, of whom two thirds were in class III before the operation. Hypertension was noticed in 70.1% of the patients (95% CI 62.9% to 77.2%). During auscultation of the lungs, abnormalities were picked up in 4.9% of the patients, while the sternum was not properly healed in 3.4% (95% VI 1.3% tot 7.2%). All the patients were on aspirin, but only 57% took an ACE inhibitor, 37% took a statin and 29% a beta-blocker.Conclusions:This study provides a picture of what to expect six weeks after a CABG.South African Family Practice Vol. 47(3) 2005: 61-6

    Identifying metabolic pathways for production of extracellular polymeric substances by the diatom Fragilariopsis cylindrus inhabiting sea ice

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    Diatoms are significant primary producers in sea ice, an ephemeral habitat with steep vertical gradients of temperature and salinity characterizing the ice matrix environment. To cope with the variable and challenging conditions, sea ice diatoms produce polysaccharide-rich extracellular polymeric substances (EPS) that play important roles in adhesion, cell protection, ligand binding and as organic carbon sources. Significant differences in EPS concentrations and chemical composition corresponding to temperature and salinity gradients were present in sea ice from the Weddell Sea and Eastern Antarctic regions of the Southern Ocean. To reconstruct the first metabolic pathway for EPS production in diatoms, we exposed Fragilariopsis cylindrus, a key bi-polar diatom species, to simulated sea ice formation. Transcriptome profiling under varying conditions of EPS production identified a significant number of genes and divergent alleles. Their complex differential expression patterns under simulated sea ice formation was aligned with physiological and biochemical properties of the cells, and with field measurements of sea ice EPS characteristics. Thus, the molecular complexity of the EPS pathway suggests metabolic plasticity in F. cylindrus is required to cope with the challenging conditions of the highly variable and extreme sea ice habitat

    Developing Literacy Learning Model Based on Multi Literacy, Integrated, and Differentiated Concept at Primary School

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    The main issue addressed in this research is the low writing skills of primary school students. One of the reasons for this condition is that the existing model of writing literacy learning is not appropriate. The purpose of this study is to explain MID-based literacy teaching model and the impact of the model in increasing primary school students\u27 writing skills. This study used combined methods of exploratory type. The samples were elementary school students coming from six schools with three different characteristics. Based on the data analysis, it can be concluded that the implementation of MID-based literacy learning model has proven to signi cantly contribute to the improvement of students\u27 writing skills. Taking place in all sample schools, the improvement may suggest that the model ts not only to students with high- ability but also those with low-ability. Therefore, the MID-based literacy learning model is needed to improve the ability to write various text types appropriately

    Ευρετικές προσεγγίσεις του μοναδιάστατου προβλήματος πακετοποίησης

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    Article 59.1, of the International Code of Nomenclature for Algae, Fungi, and Plants (ICN; Melbourne Code), which addresses the nomenclature of pleomorphic fungi, became effective from 30 July 2011. Since that date, each fungal species can have one nomenclaturally correct name in a particular classification. All other previously used names for this species will be considered as synonyms. The older generic epithet takes priority over the younger name. Any widely used younger names proposed for use, must comply with Art. 57.2 and their usage should be approved by the Nomenclature Committee for Fungi (NCF). In this paper, we list all genera currently accepted by us in Dothideomycetes (belonging to 23 orders and 110 families), including pleomorphic and non-pleomorphic genera. In the case of pleomorphic genera, we follow the rulings of the current ICN and propose single generic names for future usage. The taxonomic placements of 1261 genera are listed as an outline. Protected names and suppressed names for 34 pleomorphic genera are listed separately. Notes and justifications are provided for possible proposed names after the list of genera. Notes are also provided on recent advances in our understanding of asexual and sexual morph linkages in Dothideomycetes. A phylogenetic tree based on four gene analyses supported 23 orders and 75 families, while 35 families still lack molecular data

    A922 Sequential measurement of 1 hour creatinine clearance (1-CRCL) in critically ill patients at risk of acute kidney injury (AKI)

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