7,156 research outputs found

    Improved understanding of the growth of blocky alpha in welded Zircaloy-4

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    Zirconium alloys are widely used in nuclear reactors as fuel cladding materials. Fuel cladding is used to contain the nuclear fuel and cladding tubes are typically sealed using welds. Welding of zirconium alloys can result in changes in the local microstructure, with the potential to grow so called 'blocky {\alpha}' grains in the welded region during subsequent thermal processing and these blocky {\alpha} grains have the potential to be detrimental to the integrity of the component. In this work, complimentary heating experiments with ex situ and in situ electron backscatter diffraction (EBSD) analysis are used to aid understanding of the blocky {\alpha} grain growth within the weld region. These experiments reveal that blocky {\alpha} grain growth is related to the parent \b{eta} (high temperature) microstructure, as grains grow adjacent to a prior \b{eta} grain boundary and the orientation of the growing {\alpha} grain can be explained using neighbourhood orientations from this prior \b{eta} grain. This growth mechanism is explained via a simple mechanism which is related to the {\alpha} grain orientations, grain boundary structures and local stored energy. Ultimately, our findings indicate that the likely grain growth (size and morphology) across the weld region can now be predicted from the initial as-welded microstructure.Comment: as submitte

    Comparison of spatial domain optimal trade-off maximum average correlation height (OT-MACH) filter with scale invariant feature transform (SIFT) using images with poor contrast and large illumination gradient

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    A spatial domain optimal trade-off Maximum Average Correlation Height (OT-MACH) filter has been previously developed and shown to have advantages over frequency domain implementations in that it can be made locally adaptive to spatial variations in the input image background clutter and normalised for local intensity changes. In this paper we compare the performance of the spatial domain (SPOT-MACH) filter to the widely applied data driven technique known as the Scale Invariant Feature Transform (SIFT). The SPOT-MACH filter is shown to provide more robust recognition performance than the SIFT technique for demanding images such as scenes in which there are large illumination gradients. The SIFT method depends on reliable local edge-based feature detection over large regions of the image plane which is compromised in some of the demanding images we examined for this work. The disadvantage of the SPOTMACH filter is its numerically intensive nature since it is template based and is implemented in the spatial domain. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

    Screening and Audit as Service-Level Strategies to Support Implementation of Australian Guidelines for Cancer Pain Management in Adults: A Feasibility Study

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    © 2019 Background: Pain in people with cancer is common but often under-recognized and under-treated. Guidelines can improve the quality of pain care, but need targeted strategies to support implementation. Aim: To test the feasibility of two service-level strategies for supporting guideline implementation: a screening system and medical record audit. Design: Multimethods. Setting: One oncology outpatient service, and one palliative care outpatient and inpatient service. Participants: Patients with advanced cancer. Methods: Patients were screened in the waiting room with a modified version of the Edmonton Symptom Assessment System-revised either electronically or in paper-based format. Feasibility indicated the percentage of patients successfully screened from the total number attending the services. An audit assessed adherence to key indicators of pain assessment and management. Feasibility thresholds were set at 75% incidence for screening and a median of 30 minutes per patient for audit. Results: Of 452 patient visits, 95% (n = 429)were successfully screened, 34% (n = 155)electronically and 61% (n = 274)paper-based. Electronic pain screening was technically challenging and time-intensive for nurses. Thirty-one patients consented to have their records audited. The median audit time was 37.5 minutes (range 10-120 minutes). Variability arose from the number and type of record (outpatient or inpatient). Adherence to indicators varied from 63% (pain assessment at first presentation)to 94% (regular pain assessment and medication prescribed at regular intervals). Conclusions: This study confirmed the need to implement evidence-based guidelines for cancer pain and generated useful insights into the feasibility of pain screening and audit

    The impact of changing provider remuneration on clinical activity and quality of care: evaluation of a pilot NHS contract in Northern Ireland

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    Objectives A pilot NHS dental contract was introduced in Northern Ireland between 2015 and 2016, which involved changing the method for paying general dental practitioners working in the NHS from Fee-For-Service (FFS) to capitation-based payments, providing an opportunity for a robust evaluation. We investigated the impact of a change in payment methods on clinical activity and the quality of care provided. Design A difference-in-difference (DiD) evaluation was applied to clinical activity data from pilot NHS dental practices in Northern Ireland compared to matched control NHS practices, and applied to a questionnaire survey of patient-rated outcomes of health outcomes and care quality. We estimated the impact on access to care, treatment activity levels, practice finances and patient-rated outcomes of care of a change from FFS to a capitation-based system for one year, as well as the impact of a reversion back to FFS at the end of the pilot period. Results The monthly number of registered patients in the pilot practices increased more than the control practices during the capitation period, by 1.5 registrations per 1,000 registered patients. The monthly reductions in the volumes of all treatments in the pilot practices during the capitation period was much larger than the control practices, with 175 fewer treatment items. All measures rapidly returned to baseline levels following reversion from capitation back to FFS. NHS income per month increased in pilot practices, by £5,920 per month (calculated on FFS item cost basis) more than controls in the capitation period. The analysis of patient questionnaires suggest found that patients notices differences only in waiting times, skill-mix and number of radiographs, but not on other measures of healthcare process and quality. Conclusion General dental practitioners working in the NHS respond rapidly and consistently to changes in provider payment methods. A move from FFS to a capitation-based system had little impact on access to care, but did produce large reductions in clinical activity and patient charge income. Patients noticed little change in the service they received. This shows that changes in remuneration contracts have the potential to meet policy goals, such as meeting the expectations of patients within a predictable cost envelope. However, it is unlikely that all policy goals can be met simply by changing payment methods. Therefore, work is also needed to identify and evaluate interventions that can complement changes in remuneration to achieve desirable outcomes

    Astrophysical implications of hypothetical stable TeV-scale black holes

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    We analyze macroscopic effects of TeV-scale black holes, such as could possibly be produced at the LHC, in what is regarded as an extremely hypothetical scenario in which they are stable and, if trapped inside Earth, begin to accrete matter. We examine a wide variety of TeV-scale gravity scenarios, basing the resulting accretion models on first-principles, basic, and well-tested physical laws. These scenarios fall into two classes, depending on whether accretion could have any macroscopic effect on the Earth at times shorter than the Sun's natural lifetime. We argue that cases with such effect at shorter times than the solar lifetime are ruled out, since in these scenarios black holes produced by cosmic rays impinging on much denser white dwarfs and neutron stars would then catalyze their decay on timescales incompatible with their known lifetimes. We also comment on relevant lifetimes for astronomical objects that capture primordial black holes. In short, this study finds no basis for concerns that TeV-scale black holes from the LHC could pose a risk to Earth on time scales shorter than the Earth's natural lifetime. Indeed, conservative arguments based on detailed calculations and the best-available scientific knowledge, including solid astronomical data, conclude, from multiple perspectives, that there is no risk of any significance whatsoever from such black holes.Comment: Version2: Minor corrections/fixed typos; updated reference

    Dvoretzky type theorems for multivariate polynomials and sections of convex bodies

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    In this paper we prove the Gromov--Milman conjecture (the Dvoretzky type theorem) for homogeneous polynomials on Rn\mathbb R^n, and improve bounds on the number n(d,k)n(d,k) in the analogous conjecture for odd degrees dd (this case is known as the Birch theorem) and complex polynomials. We also consider a stronger conjecture on the homogeneous polynomial fields in the canonical bundle over real and complex Grassmannians. This conjecture is much stronger and false in general, but it is proved in the cases of d=2d=2 (for kk's of certain type), odd dd, and the complex Grassmannian (for odd and even dd and any kk). Corollaries for the John ellipsoid of projections or sections of a convex body are deduced from the case d=2d=2 of the polynomial field conjecture
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