17,946 research outputs found

    Second-line antiretroviral therapy in a workplace and community-based treatment programme in South Africa: determinants of virological outcome.

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    : Background: As antiretroviral treatment (ART) programmes in resource-limited settings mature, more patients are experiencing virological failure. Without resistance testing, deciding who should switch to second-line ART can be difficult. The consequences for second-line outcomes are unclear. In a workplace- and community-based multi-site programme, with 6-monthly virological monitoring, we describe outcomes and predictors of viral suppression on second-line, protease inhibitor-based ART.Methods: We used prospectively collected clinic data from patients commencing first-line ART between 1/1/03 and 31/12/08 to construct a study cohort of patients switched to second-line ART in the presence of a viral load (VL) ?400 copies/ml. Predictors of VL<400 copies/ml within 15 months of switch were assessed using modified Poisson regression to estimate risk ratios.Results: 205 workplace patients (91.7% male; median age 43 yrs) and 212 community patients (38.7% male; median age 36 yrs) switched regimens. At switch compared to community patients, workplace patients had a longer duration of viraemia, higher VL, lower CD4 count, and higher reported non-adherence on first-line ART. Non-adherence was the reported reason for switching in a higher proportion of workplace patients. Following switch, 48.3% (workplace) and 72.0% (community) achieved VL<400, with non-adherence (17.9% vs. 1.4%) and virological rebound (35.6% vs. 13.2% with available measures) reported more commonly in the workplace programme. In adjusted analysis of the workplace programme, lower switch VL and younger age were associated with VL<400. In the community programme, shorter duration of viraemia, higher CD4 count and transfers into programme on ART were associated with VL<400.Conclusion: High levels of viral suppression on second-line ART can be, but are not always, achieved in multi-site treatment programmes with both individual- and programme-level factors influencing outcomes. Strategies to support both healthcare workers and patients during this switch period need to be evaluated; sub-optimal adherence, particularly in the workplace programme must be addressed

    Multidimensional integrable systems and deformations of Lie algebra homomorphisms

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    We use deformations of Lie algebra homomorphisms to construct deformations of dispersionless integrable systems arising as symmetry reductions of anti--self--dual Yang--Mills equations with a gauge group Diff(S1)(S^1).Comment: 14 pages. An example of a reduction to the Beltrami equation added. New title. Final version, published in JM

    Suppression of Superconductivity in Mesoscopic Superconductors

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    We propose a new boundary-driven phase transition associated with vortex nucleation in mesoscopic superconductors (of size of the order of, or larger than, the penetration depth). We derive the rescaling equations and we show that boundary effects associated with vortex nucleation lowers the conventional transition temperature in mesoscopic superconductors by an amount which is a function of the size of the superconductor. This result explains recent experiments in small superconductors where it was found that the transition temperature depends on the size of the system and is lower than the critical Berezinsk\u{i}-Kosterlitz-Thouless temperature.Comment: To appear in Phys. Rev. Lett. Vol. 86 (15 Jan. 2001

    Solutions in Self-Dual Gravity Constructed Via Chiral Equations

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    The chiral model for self-dual gravity given by Husain in the context of the chiral equations approach is discussed. A Lie algebra corresponding to a finite dimensional subgroup of the group of symplectic diffeomorphisms is found, and then use for expanding the Lie algebra valued connections associated with the chiral model. The self-dual metric can be explicitly given in terms of harmonic maps and in terms of a basis of this subalgebra.Comment: Plain Latex, 13 Pages, major revisions of style in the above proof, several Comments added. Version to appear in Physical Review

    Aerosol major ion record at Mount Washington

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    This study examined the seasonal cycles and regional-scale meteorological controls on the chemical properties of bulk aerosols collected from 1999 to 2004 at Mount Washington, the highest peak in the northeastern United States. The concentrations of NH4+ and SO42− peaked during summer months. The pattern for aerosol NO3− was more complicated with relatively high median concentrations characterizing spring and summer months, but with major elevated events occurring during fall, winter, and spring. The seasonal relationship between NH4+ and SO42− indicated that during warmer months a mixture of (NH4)2SO4 and NH4HSO4 was present, while it was mainly the latter in winter. More acidity and higher concentrations of the major species were generally associated with winds from the southwest and west sectors. The highest (≥95th percentile) concentrations of SO42− and NH4+ were associated with air mass transport from major upwind source regions in the Midwest and along the eastern seaboard. The ionic composition and seasonal cycle observed at Mount Washington were similar to those measured at other northeastern sites, but the range and average concentrations were much lower. These differences were exaggerated during wintertime. Included in this paper are several Eulerian case studies of SO2 conversion to SO42− during transit from Whiteface Mountain, New York, to Mount Washington. The calculations suggest a gas-phase SO2 oxidation rate of ∼1–2% per hour and demonstrate the possibility of using these two sites to investigate the chemical evolution of air masses as they move from Midwestern source regions to northern New England

    Dual kinetic balance approach to basis set expansions for the Dirac equation

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    A new approach to finite basis sets for the Dirac equation is developed. It solves the problem of spurious states and, as a result, improves the convergence properties of basis set calculations. The efficiency of the method is demonstrated for finite basis sets constructed from B splines by calculating the one-loop self-energy correction for a hydrogenlike ion.Comment: 14 pages, 1 tabl

    Co-Designing a Programme Level Approach to Information and Digital Literacy: Initial Reflections from Our Participatory Action Research Project

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    Information and digital literacy (IDL) is a core graduate attribute at the University of Sheffield and is defined as follows: “Information and digital literacy (IDL) enables engaged learning. It blends information literacies with digital capabilities transcending technological skills and tools to identify with learning, living and working in a fluid digital world. IDL enables learners to discover and absorb information in a critically engaged manner, innovate in active pursuits of creative scholarship, demonstrate integrity by acknowledging the work of others and make a contribution for others to share” [University of Sheffield Library, 2019]. This paper will present initial reflections from an innovative participatory action research project established at the University, to bring a team of student associates together with a team of faculty liaison librarians to co-build and co-embed a programme level approach (PLA) to IDL. PLA takes a holistic rather than modular approach to learning and teaching, allowing students to develop the knowledge, skills and attributes that will make them confident and assured graduates. The University has set an ambitious five-year strategic vision to ensure every course has a programme level approach by the year 2021 [University of Sheffield, 2016]. US based librarians Susan Gardner Archambault & Jennifer Masunaga [2015] maintain that libraries can contribute to such ambitious programme level approaches by taking the initiative and by working with academic and administrative staff to map information (and digital) literacy into the curriculum. Our work aims to build on this by also including the student voice in our mapping work, taking a participatory action research approach [Heron & Reason, 2008] to engage, include and embrace the student experience. The success and impact of this work will be assessed through staff and student reflections and we will draw on these to present success to date, at the IATUL 2019 annual conference

    Impact of serum source on human mesenchymal stem cell osteogenic differentiation in culture

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    Human mesenchymal stem cells (MSCs) show promise for musculoskeletal repair applications. Animal-derived serum is extensively used for MSC culture as a source of nutrients, extracellular matrix proteins and growth factors. However, the routine use of fetal calf serum (FCS) is not innocuous due to its animal antigens and ill-defined composition, driving the development of alternatives protocols. The present study sought to reduce exposure to FCS via the transient use of human serum. Transient exposure to animal serum had previously proved successful for the osteogenic differentiation of MSCs but had not yet been tested with alternative serum sources. Here, human serum was used to support the proliferation of MSCs, which retained surface marker expression and presented higher alkaline phosphatase activity than those in FCS-based medium. Addition of osteogenic supplements supported strong mineralisation over a 3-week treatment. When limiting serum exposure to the first five days of treatment, MSCs achieved higher differentiation with human serum than with FCS. Finally, human serum analysis revealed significantly higher levels of osteogenic components such as alkaline phosphatase and 25-Hydroxyvitamin D, consistent with the enhanced osteogenic effect. These results indicate that human serum used at the start of the culture offers an efficient replacement for continuous FCS treatment and could enable short-term exposure to patient-derived serum in the future
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