126 research outputs found

    Nuclear security and Somalia

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    Development of muon scattering tomography for a detection of reinforcement in concrete

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    Inspection of ageing, reinforced concrete structures is a world-wide challenge. Existing non-destructive evaluation techniques in civil and structural engineering have limited penetration depth and don't allow to precisely ascertain the configuration of reinforcement within large concrete objects. The big challenge for critical infrastructure (bridges, dams, dry docks, nuclear bioshields etc.) is understanding the internal condition of the concrete and steel, not just the location of the reinforcement. In most new constructions the location should be known and recorded in the as-built drawings, where these might not exist due to poor record keeping for older structures. Muon scattering tomography is a non-destructive and non-invasive technique which shows great promise for high-depth 3D concrete imaging. Previously, we have demonstrated that individual bars with a diameter of 33.7 +- 7.3 mm at 50 cm depth can be located using muon scattering tomography. Here we present an improved method that exploits the periodicity of bar structures. With this new method, reinforcement with bars down to 6 mm thickness can be detected and imaged

    A Novel Approach to Contamination Suppression in Transmission Detectors for Radiotherapy

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    The current trend in X-ray radiotherapy is to treat cancers that are in difficult locations in the body using beams with a complex intensity profile. Intensity Modulated Radiotherapy (IMRT) is a treatment which improves the dose distribution to the tumour whilst reducing the dose to healthy tissue. Such treatments administer a larger dose per treatment fraction and hence require more complex methods to verify the accuracy of the treatment delivery. Measuring beam intensity fluctuations is difficult as the beam is heavily distorted after leaving thepatient and transmission detectors will attenuate the beam and change the energy spectrum of the beam. Monolithic Active Pixel Sensors (MAPS) are ideal solid-state detectors to measure the 2D beam profile of a radiotherapy beam upstream of the patient. MAPS sensors can be made very thin (āˆ¼ 30 Ī¼m) with still very good signal-to-noise performance. This means that the beam would pass through the sensor virtually undisturbed(< 1% attenuation). Pixel pitches of between 2 Ī¼m to 100 Ī¼m are commercially available. Large area devices (āˆ¼ 15 Ɨ 15 cm 2 ) have been produced. MAPS can be made radiation hard enough to befully functional after a large number of fractions. All this makes MAPS a very realistic transmission detector candidate for beam monitoring upstream of the patient. A remaining challenge for thin, upstream sensors is that the detectors are sensitive to the signal of both therapeutic photons and electron contamination. Here a method is presented to distinguish between the signal due to electrons and photons and thus provide real-time dosimetric information in very thin sensors that does not require Monte Carlo simulation of each linear accelerator treatment head

    Non-destructive assay of nuclear waste containers using muon scattering tomography in the Horizon2020 CHANCE project

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    Methods for the non-destructive assay of nuclear waste drums are of great importance to the nuclear waste management community, especially where loss in continuity of knowledge about the content of drums happened or chemical processes altering the contents of the drums may occur. Muon scattering tomography has been shown to be a promising technique for the non-destructive assay of nuclear waste drums in a safe way. By measuring tracks of muons entering and leaving the probed sample and extracting scattering angles from the tracks, it is possible to draw conclusions about the contents of the sample and its spatial arrangement. Within the CHANCE project, a newly built large-scale mobile detector system for scanning and imaging the contents of nuclear waste drums using atmospheric muons is currently undergoing commissioning

    Epoetin Beta and C-Terminal Fibroblast Growth Factor 23 in Patients With Chronic Heart Failure and Chronic Kidney Disease

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    Background In patients with chronic heart failure and chronic kidney disease, correction of anemia with erythropoietin-stimulating agents targeting normal hemoglobin levels is associated with an increased risk of cardiovascular morbidity and mortality. Emerging data suggest a direct effect of erythropoietin on fibroblast growth factor 23 (FGF23), elevated levels of which have been associated with adverse outcomes. We investigate effects of erythropoietin-stimulating agents in patients with both chronic heart failure and chronic kidney disease focusing on FGF23. Methods and Results In the EPOCARES (Erythropoietin in CardioRenal Syndrome) study, we randomized 56 anemic patients (median age 74 [interquartile range 69-80] years, 66% male) with both chronic heart failure and chronic kidney disease into 3 groups, of which 2 received epoetin beta 50 IU/kg per week for 50 weeks, and the third group served as control. Measurements were performed at baseline and after 2, 26, and 50 weeks. Data were analyzed using linear mixed-model analysis. After 50 weeks of erythropoietin-stimulating agent treatment, hematocrit and hemoglobin levels increased. Similarly, C-terminal FGF23 levels, in contrast to intact FGF23 levels, rose significantly due to erythropoietin-stimulating agents as compared with the controls. During median follow-up for 5.7 (2.0-5.7) years, baseline C-terminal FGF23 levels were independently associated with increased risk of mortality (hazard ratio 2.20; 95% CI, 1.35-3.59; P=0.002). Conclusions Exogenous erythropoietin increases C-terminal FGF23 levels markedly over a period of 50 weeks, elevated levels of which, even at baseline, are significantly associated with an increased risk of mortality. The current results, in a randomized trial setting, underline the strong relationship between erythropoietin and FGF23 physiology in patients with chronic heart failure and chronic kidney disease. Clinical Trial Registration URL: http://www.clinicaltrials.gov. Unique identifier: NCT00356733
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