2,424 research outputs found

    Holographic imaging of antiferromagnetic domains with in-situ magnetic field

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    Lensless coherent x-ray imaging techniques have great potential for high-resolution imaging of magnetic systems with a variety of in-situ perturbations. Despite many investigations of ferromagnets, extending these techniques to the study of other magnetic materials, primarily antiferromagnets, is lacking. Here, we demonstrate the first (to our knowledge) study of an antiferromagnet using holographic imaging through the "holography with extended reference by autocorrelation linear differential operation" technique. Energy-dependent contrast with both linearly and circularly polarised x-rays are demonstrated. Antiferromagnetic domains and topological textures are studied in the presence of applied magnetic fields, demonstrating quasi-cyclic domain reconfiguration up to 500 mT.Comment: 14 pages, 6 figure

    Turbine airfoil net heat flux reduction with cylindrical holes embedded in a transverse trench.

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    ABSRACT Film cooling adiabatic effectiveness and heat transfer coefficients for cylindrical holes embedded in a 1d transverse trench on the suction side of a simulated turbine vane were investigated to determine the net heat flux reduction. For reference, measurements were also conducted with standard inclined, cylindrical holes. Heat transfer coefficients were determined with and without upstream heating to isolate the hydrodynamic effects of the trench and to investigate the effects of the thermal approach boundary layer. Also the effects of a tripped versus an un-tripped boundary layer were explored. For both the cylindrical holes and the trench, heat transfer augmentation was much greater with no tripping of the approach flow. A further increase in heat transfer augmentation was caused by use of upstream heating, with as much as a 150% augmentation with the trench. With a tripped approach flow the heat transfer augmentation was much less. The net heat flux reduction for the trench was found to be significantly higher than for the row of cylindrical holes

    Mitigation measures to reduce entanglements of migrating whales with commercial fishing gear

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    The West Coast Rock Lobster Managed Fishery (WCRLMF) transitioned to a quota based fishery, and year-round fishing, which corresponded with a spike in whale entanglements in 2013. This presented industry with a challenging social issue, to reduce entanglements without impacting on the financial benefits that the shift to year-round quota fishing had afforded

    Carbonium vs. carbenium ion-like transition state geometries for carbocation cyclization – how strain associated with bridging affects 5-exo vs. 6-endo selectivity

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    Quantum chemical calculations are used to explore the origins of regioselectivity for proton-, Pt(II)- and Pd(II)-promoted cyclizations of 1,5-hexadienes, 5-aminoalkenes, and allylic acetimidates. The strain associated with achieving carbonium ion-like transition state geometries is shown to be a key factor in controlling 5-exo vs. 6-endo selectivity

    Structural basis for potency differences between GDF8 and GDF11.

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    BACKGROUND: Growth/differentiation factor 8 (GDF8) and GDF11 are two highly similar members of the transforming growth factor β (TGFβ) family. While GDF8 has been recognized as a negative regulator of muscle growth and differentiation, there are conflicting studies on the function of GDF11 and whether GDF11 has beneficial effects on age-related dysfunction. To address whether GDF8 and GDF11 are functionally identical, we compared their signaling and structural properties. RESULTS: Here we show that, despite their high similarity, GDF11 is a more potent activator of SMAD2/3 and signals more effectively through the type I activin-like receptor kinase receptors ALK4/5/7 than GDF8. Resolution of the GDF11:FS288 complex, apo-GDF8, and apo-GDF11 crystal structures reveals unique properties of both ligands, specifically in the type I receptor binding site. Lastly, substitution of GDF11 residues into GDF8 confers enhanced activity to GDF8. CONCLUSIONS: These studies identify distinctive structural features of GDF11 that enhance its potency, relative to GDF8; however, the biological consequences of these differences remain to be determined

    Hepatitis B Seroprevalence in the U.S. Military and its Impact on Potential Screening Strategies

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    INTRODUCTION: Knowledge of the contemporary epidemiology of hepatitis B virus (HBV) infection among military personnel can inform potential Department of Defense (DoD) screening policy and infection and disease control strategies. MATERIALS AND METHODS: HBV infection status at accession and following deployment was determined by evaluating reposed serum from 10,000 service members recently deployed to combat operations in Iraq and Afghanistan in the period from 2007 to 2010. A cost model was developed from the perspective of the Department of Defense for a program to integrate HBV infection screening of applicants for military service into the existing screening program of screening new accessions for vaccine-preventable infections. RESULTS: The prevalence of chronic HBV infection at accession was 2.3/1,000 (95% CI: 1.4, 3.2); most cases (16/21, 76%) identified after deployment were present at accession. There were 110 military service-related HBV infections identified. Screening accessions who are identified as HBV susceptible with HBV surface antigen followed by HBV surface antigen neutralization for confirmation offered no cost advantage over not screening and resulted in a net annual increase in cost of $5.78 million. However, screening would exclude as many as 514 HBV cases each year from accession. CONCLUSIONS: Screening for HBV infection at service entry would potentially reduce chronic HBV infection in the force, decrease the threat of transfusion-transmitted HBV infection in the battlefield blood supply, and lead to earlier diagnosis and linkage to care; however, applicant screening is not cost saving. Service-related incident infections indicate a durable threat, the need for improved laboratory-based surveillance tools, and mandate review of immunization policy and practice

    Low Energy Nuclear Reaction Aircraft- 2013 ARMD Seedling Fund Phase I Project

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    This report serves as the final written documentation for the Aeronautic Research Mission Directorate (ARMD) Seedling Fund's Low Energy Nuclear Reaction (LENR) Aircraft Phase I project. The findings presented include propulsion system concepts, synergistic missions, and aircraft concepts. LENR is a form of nuclear energy that potentially has over 4,000 times the energy density of chemical energy sources. It is not expected to have any harmful emissions or radiation which makes it extremely appealing. There is a lot of interest in LENR, but there are no proven theories. This report does not explore the feasibility of LENR. Instead, it assumes that a working system is available. A design space exploration shows that LENR can enable long range and high speed missions. Six propulsion concepts, six missions, and four aircraft concepts are presented. This report also includes discussion of several issues and concerns that were uncovered during the study and potential research areas to infuse LENR aircraft into NASA's aeronautics research

    Protocol for a prospective cohort study of open tibia fractures in Malawi with a nested implementation of open fracture guidelines.

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    Background: Road traffic injury (RTI) is the largest cause of death amongst 15-39-year-old people worldwide, and the burden of injuries such as open tibia fractures are rapidly increasing in Malawi. This study aims to investigate disability and economic outcomes of people with open tibia fractures in Malawi and improve these with locally delivered implementation of open fracture guidelines. Methods: This is a prospective cohort study describing function, quality of life and economic burden of open tibia fractures in Malawi. In total, 160 participants will be recruited across six centres and will be followed-up with face-to-face interviews at six weeks, three months, six months and one year following injury. The primary outcome will be function at one year measured by the short musculoskeletal functional assessment (SMFA) score. Secondary outcomes will include quality of life measured by EuroQol EQ-5D-3L, catastrophic loss of income and implementation outcomes (acceptability, adoption, appropriateness, costs, feasibility, fidelity, penetration, and sustainability) at one year. A nested pilot pre-post implementation study of an interventional bundle for all open fractures will be developed based on other implementation studies from low- and middle-income countries (LMICs). Regression analysis will be used to model and investigate associations between SMFA score and fracture severity, infection and the pre- and post-training course period. Outcome: This prospective cohort study will report patient reported outcomes from open tibia fractures in low-resource settings. Subsequent detailed evaluation of both the clinical and implementation components of the study will promote sustainability of improved open fractures management in the study sites and further scale-up of open fracture management guidelines. Ethics: Ethics approval has been obtained from the Liverpool School of Tropical Medicine and College of Medicine Research and Ethics committee
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