4,794 research outputs found

    ANCA in systemic sclerosis, when vasculitis overlaps with vasculopathy: a devastating combination of pathologies

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    In patients with systemic sclerosis (SSc), the coexistence of ANCA-associated vasculitis (SSc-AAV) has been reported to be associated with a severe disease course, including significant pulmonary and renal involvement. The presence of ANCA is not uncommon in patients with SSc and therefore clinicians must maintain a high index of clinical suspicion about SSc-AAV. p-ANCA and anti-MPO antibodies are the most common antibodies observed. Patients typically present with clinical features of microscopic polyangiitis or renal-limited vasculitis There are multiple areas of potential interaction in the pathogenesis of SSc and AAV which can exacerbate/compound vascular disease. In addition, similar patterns of major internal organ involvement (e.g., lung and kidneys) are seen in both conditions. We highlight a diagnostic approach to SSc-AAV and the paucity of data to inform management. As such, SSc-AAV is typically treated as per isolated AAV which can potentially be hazardous in patients with SSc (e.g., the association between high-dose steroid and scleroderma renal crisis). We propose that this rare clinical entity warrants rigorous investigation including definition of a therapeutic strategy to ameliorate the potentially devastating combination of pathologies in SSc-AAV

    Communities in university mathematics

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    This paper concerns communities of learners and teachers that are formed, develop and interact in university mathematics environments through the theoretical lens of Communities of Practice. From this perspective, learning is described as a process of participation and reification in a community in which individuals belong and form their identity through engagement, imagination and alignment. In addition, when inquiry is considered as a fundamental mode of participation, through critical alignment, the community becomes a Community of Inquiry. We discuss these theoretical underpinnings with examples of their application in research in university mathematics education and, in more detail, in two Research Cases which focus on mathematics students' and teachers' perspectives on proof and on engineering students' conceptual understanding of mathematics. The paper concludes with a critical reflection on the theorising of the role of communities in university level teaching and learning and a consideration of ways forward for future research

    Dynamics of viscoelastic membranes

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    We determine both the in-plane and out-of-plane dynamics of viscoelastic membranes separating two viscous fluids in order to understand microrheological studies of such membranes. We demonstrate the general viscoelastic signatures in the dynamics of shear, bending, and compression modes. We also find a screening of the otherwise two-dimensional character of the response to point forces due to the presence of solvent. Finally, we show that there is a linear, hydrodynamic coupling between the in-plane compression modes of the membrane and the out-of-plane bending modes in the case where the membrane separates two different fluids or environments

    Observational Limit on Gravitational Waves from Binary Neutron Stars in the Galaxy

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    Using optimal matched filtering, we search 25 hours of data from the LIGO 40-meter prototype laser interferometric gravitational-wave detector for gravitational-wave chirps emitted by coalescing binary systems within our Galaxy. This is the first test of this filtering technique on real interferometric data. An upper limit on the rate R of neutron star binary inspirals in our Galaxy is obtained: with 90% confidence, R< 0.5/hour. Similar experiments with LIGO interferometers will provide constraints on the population of tight binary neutron star systems in the Universe.Comment: RevTeX, minor revisions, exactly as published in PRL 83 (1999) p1498, 4 pages, 2 figures include

    Transport Through Andreev Bound States in a Graphene Quantum Dot

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    Andreev reflection-where an electron in a normal metal backscatters off a superconductor into a hole-forms the basis of low energy transport through superconducting junctions. Andreev reflection in confined regions gives rise to discrete Andreev bound states (ABS), which can carry a supercurrent and have recently been proposed as the basis of qubits [1-3]. Although signatures of Andreev reflection and bound states in conductance have been widely reported [4], it has been difficult to directly probe individual ABS. Here, we report transport measurements of sharp, gate-tunable ABS formed in a superconductor-quantum dot (QD)-normal system, which incorporates graphene. The QD exists in the graphene under the superconducting contact, due to a work-function mismatch [5, 6]. The ABS form when the discrete QD levels are proximity coupled to the superconducting contact. Due to the low density of states of graphene and the sensitivity of the QD levels to an applied gate voltage, the ABS spectra are narrow, can be tuned to zero energy via gate voltage, and show a striking pattern in transport measurements.Comment: 25 Pages, included SO

    A Shell Model Study of the High Spin States of \u3csup\u3e88\u3c/sup\u3eY

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    Experiments were carried out at the Wright Nuclear Structure Laboratory at Yale University using the 21MV ESTU Tandem Van de Graaff accelerator with the purpose of studying 88Y. A beam of 18O impinged at laboratory energies of 60, 65 and 70 MeV on a 600 μg/cm 2 74Ge target with a thick (10mg/cm 2) 197Au backing. This experiment was performed with the specific aim of accessing medium spin states of the nucleus of interest. A second experiment was undertaken to populate the nucleus of interest in higher spin states by impinging the same 18O beam on a thin 62 μg/cm 2 76Ge target with a 20 μg/cm2 carbon backing at a laboratory beam energy of 90 MeV. Gamma rays emitted following the decay of excited states in 88Y and other nuclei populated in the reactions were measured using the YRAST ball detector array, consisting of 10 Compton suppressed HPGe clover detectors. In conjunction with the experimental study presented here, nuclear shell model calculations using a truncated valence space have also been performed in an attempt to describe the single-particle make-up of the states observed. Preliminary results from these experiments and theoretical calculations are presented

    Prescribing practices of primary-care veterinary practitioners in dogs diagnosed with bacterial pyoderma

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    Concern has been raised regarding the potential contributions of veterinary antimicrobial use to increasing levels of resistance in bacteria critically important to human health. Canine pyoderma is a frequent, often recurrent diagnosis in pet dogs, usually attributable to secondary bacterial infection of the skin. Lesions can range in severity based on the location, total area and depth of tissue affected and antimicrobial therapy is recommended for resolution. This study aimed to describe patient signalment, disease characteristics and treatment prescribed in a large number of UK, primary-care canine pyoderma cases and to estimate pyoderma prevalence in the UK vet-visiting canine population

    High-Spin Study of the Shell Model Nucleus \u3csup\u3e88\u3c/sup\u3eY\u3csub\u3e49\u3c/sub\u3e

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    The near-yrast structure of the near-magic, odd-odd nucleus, 8839Y49, has been studied into the high-spin regime. Investigations were performed at the Wright Nuclear Structure Laboratory, Yale University, using the 74Ge(18O,p3n) and 76Ge(18O,p5n) fusion-evaporation reactions at beam energies of 60 and 90 MeV, respectively. Gamma-ray energy coincidence analyses using both double (γ2) and triple (γ3) fold coincidences, together with angular correlation measurements, have been used to extend the previously reported level scheme to an excitation energy of 8.6 MeV and a spin and parity of 19(−). The presented level scheme is compared with predictions of a truncated valence space shell-model calculation, which assumes an inert 56Ni core with proton and neutron excitations allowed within the f5/2, p3/2, p1/2, and g9/2 single-particle states. The shell-model calculations show a reasonable comparison with the experimental data for the yrast, positive-parity states up to spin 18 ℏ, with larger variations evident for negative-parity states with spins greater than 16 ℏ. In spite of a significant increase in angular momentum input associated with the thin target 76Ge(18O,p5n) reaction channel, as compared to the backed target data using the 74Ge target, no additional discrete states were identified in the former data set, suggesting that the level scheme for this nucleus fragments significantly above the observed states, possibly indicating cross-shell excitations becoming dominant for I \u3e19 ℏ

    A framework to assist in the analysis of risks and rewards of adopting BIM for SMEs in the UK

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    © 2017 The Author(s) Published by VGTU Press and Informa UK Limited, [trading as Taylor & Francis Group]. Building information modelling (BIM) adoption amongst larger construction firms and innovators seems to be on the increase. However, there is evidence to suggest that small and medium sized enterprises (SMEs) are currently lagging behind and are losing out in winning publicly funded projects. Guidance and frameworks to assist SMEs to make an informed decision about BIM adoption are currently lacking. There has been no systematic effort to date to bring together the results of research in SMEs’ BIM adoption. Consequently, this paper seeks to bridge this gap and provide a conceptual framework to give a theoretical foundation to the study of brokering risks and rewards in the adoption of BIM for project delivery. This framework is comprehensive and includes trading off risks and rewards associated with several criteria, such as stage of involvement, project value, funding, and the procurement route chosen. The approach has been validated by a representative sample of BIM users and the findings of the validation are also presented. The findings of the framework validation reveal that early design stage, project size between £5 m and £50 m, private funding, and integrated project delivery procurement are the best opportunities that enable SMEs to maximise the benefits and minimise the risks, when adopting BIM

    Effects of dissipation on quantum phase transitions

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    We discuss the effect of dissipation on quantum phase transitions. In particular we concentrate on the Superconductor to Insulator and Quantum-Hall to Insulator transitions. By invoking a phenomenological parameter α\alpha to describe the coupling of the system to a continuum of degrees of freedom representing the dissipative bath, we obtain new phase diagrams for the quantum Hall and superconductor-insulator problems. Our main result is that, in two-dimensions, the metallic phases observed in finite magnetic fields (possibly also strictly zero field) are adiabatically deformable from one to the other. This is plausible, as there is no broken symmetry which differentiates them.Comment: 13 pages, 4 figure
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