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- Abel, I, et al.
(författare)
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Overview of the JET results with the ITER-like wall
- 2013
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
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Tidskriftsartikel (refereegranskat)abstract
- Following the completion in May 2011 of the shutdown for the installation of the beryllium wall and the tungsten divertor, the first set of JET campaigns have addressed the investigation of the retention properties and the development of operational scenarios with the new plasma-facing materials. The large reduction in the carbon content (more than a factor ten) led to a much lower Z(eff) (1.2-1.4) during L- and H-mode plasmas, and radiation during the burn-through phase of the plasma initiation with the consequence that breakdown failures are almost absent. Gas balance experiments have shown that the fuel retention rate with the new wall is substantially reduced with respect to the C wall. The re-establishment of the baseline H-mode and hybrid scenarios compatible with the new wall has required an optimization of the control of metallic impurity sources and heat loads. Stable type-I ELMy H-mode regimes with H-98,H-y2 close to 1 and beta(N) similar to 1.6 have been achieved using gas injection. ELM frequency is a key factor for the control of the metallic impurity accumulation. Pedestal temperatures tend to be lower with the new wall, leading to reduced confinement, but nitrogen seeding restores high pedestal temperatures and confinement. Compared with the carbon wall, major disruptions with the new wall show a lower radiated power and a slower current quench. The higher heat loads on Be wall plasma-facing components due to lower radiation made the routine use of massive gas injection for disruption mitigation essential.
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| 2. |
- Romanelli, F, et al.
(författare)
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Overview of the JET results
- 2011
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
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Tidskriftsartikel (refereegranskat)abstract
- Since the last IAEA Conference JET has been in operation for one year with a programmatic focus on the qualification of ITER operating scenarios, the consolidation of ITER design choices and preparation for plasma operation with the ITER-like wall presently being installed in JET. Good progress has been achieved, including stationary ELMy H-mode operation at 4.5 MA. The high confinement hybrid scenario has been extended to high triangularity, lower ρ*and to pulse lengths comparable to the resistive time. The steady-state scenario has also been extended to lower ρ*and ν*and optimized to simultaneously achieve, under stationary conditions, ITER-like values of all other relevant normalized parameters. A dedicated helium campaign has allowed key aspects of plasma control and H-mode operation for the ITER non-activated phase to be evaluated. Effective sawtooth control by fast ions has been demonstrated with3He minority ICRH, a scenario with negligible minority current drive. Edge localized mode (ELM) control studies using external n = 1 and n = 2 perturbation fields have found a resonance effect in ELM frequency for specific q95values. Complete ELM suppression has, however, not been observed, even with an edge Chirikov parameter larger than 1. Pellet ELM pacing has been demonstrated and the minimum pellet size needed to trigger an ELM has been estimated. For both natural and mitigated ELMs a broadening of the divertor ELM-wetted area with increasing ELM size has been found. In disruption studies with massive gas injection up to 50% of the thermal energy could be radiated before, and 20% during, the thermal quench. Halo currents could be reduced by 60% and, using argon/deuterium and neon/deuterium gas mixtures, runaway electron generation could be avoided. Most objectives of the ITER-like ICRH antenna have been demonstrated; matching with closely packed straps, ELM resilience, scattering matrix arc detection and operation at high power density (6.2 MW m-2) and antenna strap voltages (42 kV). Coupling measurements are in very good agreement with TOPICA modelling. © 2011 IAEA, Vienna.
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| 9. |
- Graham, HR, et al.
(författare)
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Cost-effectiveness and sustainability of improved hospital oxygen systems in Nigeria
- 2022
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Ingår i: BMJ global health. - : BMJ. - 2059-7908. ; 7:8
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Tidskriftsartikel (refereegranskat)abstract
- Improving hospital oxygen systems can improve quality of care and reduce mortality for children, but we lack data on cost-effectiveness or sustainability. This study evaluated medium-term sustainability and cost-effectiveness of the Nigeria Oxygen Implementation programme.MethodsProspective follow-up of a stepped-wedge trial involving 12 secondary-level hospitals. Cross-sectional facility assessment, clinical audit (January–March 2021), summary admission data (January 2018–December 2020), programme cost data. Intervention: pulse oximetry introduction followed by solar-powered oxygen system installation with clinical and technical training and support. Primary outcomes: (i) proportion of children screened with pulse oximetry; (ii) proportion of hypoxaemic (SpO2 <90%) children who received oxygen. Comparison across three time periods: preintervention (2014–2015), intervention (2016–2017) and follow-up (2018–2020) using mixed-effects logistic regression. Calculated cost-effectiveness of the intervention on child pneumonia mortality using programme costs, recorded deaths and estimated counterfactual deaths using effectiveness estimates from our effectiveness study. Reported cost-effectiveness over the original 2-year intervention period (2016–2017) and extrapolated over 5 years (2016–2020).ResultsPulse oximetry coverage for neonates and children remained high during follow-up (83% and 81%) compared with full oxygen system period (94% and 92%) and preintervention (3.9% and 2.9%). Oxygen coverage for hypoxaemic neonates/children was similarly high (94%/88%) compared with full oxygen system period (90%/82%). Functional oxygen sources were present in 11/12 (92%) paediatric areas and all (8/8) neonatal areas; three-quarters (15/20) of wards had a functional oximeter. Of 32 concentrators deployed, 23/32 (72%) passed technical testing and usage was high (median 10 797 hours). Estimated 5-year cost-effectiveness US$86 per patient treated, $2694–4382 per life saved and $82–125 per disability-adjusted life year-averted. We identified practical issues for hospitals and Ministries of Health wishing to adapt and scale up pulse oximetry and oxygen.ConclusionHospital-level improvements to oxygen and pulse oximetry systems in Nigerian hospitals have been sustained over the medium-term and are a highly cost-effective child pneumonia intervention.
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| 10. |
- Graham, HR, et al.
(författare)
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Measuring oxygen access: lessons from health facility assessments in Lagos, Nigeria
- 2021
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Ingår i: BMJ global health. - : BMJ. - 2059-7908. ; 6:8
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Tidskriftsartikel (refereegranskat)abstract
- The COVID-19 pandemic has highlighted global oxygen system deficiencies and revealed gaps in how we understand and measure ‘oxygen access’. We present a case study on oxygen access from 58 health facilities in Lagos state, Nigeria. We found large differences in oxygen access between facilities (primary vs secondary, government vs private) and describe three key domains to consider when measuring oxygen access: availability, cost, use. Of 58 facilities surveyed, 8 (14%) of facilities had a functional pulse oximeter. Oximeters (N=27) were typically located in outpatient clinics (12/27, 44%), paediatric ward (6/27, 22%) or operating theatre (4/27, 15%). 34/58 (59%) facilities had a functional source of oxygen available on the day of inspection, of which 31 (91%) facilities had it available in a single ward area, typically the operating theatre or maternity ward. Oxygen services were free to patients at primary health centres, when available, but expensive in hospitals and private facilities, with the median cost for 2 days oxygen 13 000 (US$36) and 27 500 (US$77) Naira, respectively. We obtained limited data on the cost of oxygen services to facilities. Pulse oximetry use was low in secondary care facilities (32%, 21/65 patients had SpO2 documented) and negligible in private facilities (2%, 3/177) and primary health centres (<1%, 2/608). We were unable to determine the proportion of hypoxaemic patients who received oxygen therapy with available data. However, triangulation of existing data suggested that no facilities were equipped to meet minimum oxygen demands. We highlight the importance of a multifaceted approach to measuring oxygen access that assesses access at the point-of-care and ideally at the patient-level. We propose standard metrics to report oxygen access and describe how these can be integrated into routine health information systems and existing health facility assessment tools.
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| 11. |
- Graham, HR, et al.
(författare)
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Pulse oximetry and oxygen services for the care of children with pneumonia attending frontline health facilities in Lagos, Nigeria (INSPIRING-Lagos): study protocol for a mixed-methods evaluation
- 2022
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Ingår i: BMJ open. - : BMJ. - 2044-6055. ; 12:5, s. e058901-
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this evaluation is to understand whether introducing stabilisation rooms equipped with pulse oximetry and oxygen systems to frontline health facilities in Ikorodu, Lagos State, alongside healthcare worker (HCW) training improves the quality of care for children with pneumonia aged 0–59 months. We will explore to what extent, how, for whom and in what contexts the intervention works.Methods and analysisQuasi-experimental time-series impact evaluation with embedded mixed-methods process and economic evaluation. Setting: seven government primary care facilities, seven private health facilities, two government secondary care facilities. Target population: children aged 0–59 months with clinically diagnosed pneumonia and/or suspected or confirmed COVID-19. Intervention: ‘stabilisation rooms’ within participating primary care facilities in Ikorodu local government area, designed to allow for short-term oxygen delivery for children with hypoxaemia prior to transfer to hospital, alongside HCW training on integrated management of childhood illness, pulse oximetry and oxygen therapy, immunisation and nutrition. Secondary facilities will also receive training and equipment for oxygen and pulse oximetry to ensure minimum standard of care is available for referred children. Primary outcome: correct management of hypoxaemic pneumonia including administration of oxygen therapy, referral and presentation to hospital. Secondary outcome: 14-day pneumonia case fatality rate. Evaluation period: August 2020 to September 2022.Ethics and disseminationEthical approval from University of Ibadan, Lagos State and University College London. Ongoing engagement with government and other key stakeholders during the project. Local dissemination events will be held with the State Ministry of Health at the end of the project (December 2022). We will publish the main impact results, process evaluation and economic evaluation results as open-access academic publications in international journals.Trial registration numberACTRN12621001071819; Registered on the Australian and New Zealand Clinical Trials Registry.
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| 14. |
- King, C, et al.
(författare)
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Prevalence of pneumonia and malnutrition among children in Jigawa state, Nigeria: a community-based clinical screening study
- 2022
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Ingår i: BMJ paediatrics open. - : BMJ. - 2399-9772. ; 6:1
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Tidskriftsartikel (refereegranskat)abstract
- To estimate the point prevalence of pneumonia and malnutrition and explore associations with household socioeconomic factors.DesignCommunity-based cross-sectional study conducted in January–June 2021 among a random sample of households across all villages in the study area.SettingKiyawa Local Government Area, Jigawa state, Nigeria.ParticipantsChildren aged 0–59 months who were permanent residents in Kiyawa and present at home at the time of the survey.Main outcome measuresPneumonia (non-severe and severe) defined using WHO criteria (2014 revision) in children aged 0–59 months. Malnutrition (moderate and severe) defined using mid-upper arm circumference in children aged 6–59 months.Results9171 children were assessed, with a mean age of 24.8 months (SD=15.8); 48.7% were girls. Overall pneumonia (severe or non-severe) point prevalence was 1.3% (n=121/9171); 0.6% (n=55/9171) had severe pneumonia. Using an alternate definition that did not rely on caregiver-reported cough/difficult breathing revealed higher pneumonia prevalence (n=258, 2.8%, 0.6% severe, 2.2% non-severe). Access to any toilet facility was associated with lower odds of pneumonia (aOR: 0.56; 95% CI: 0.31 to 1.01). The prevalence of malnutrition (moderate or severe) was 15.6% (n=1239/7954) with 4.1% (n=329/7954) were severely malnourished. Being older (aOR: 0.22; 95% CI: 0.17 to 0.27), male (aOR: 0.77; 95% CI: 0.66 to 0.91) and having head of compound a business owner or professional (vs subsistence farmer, aOR 0.71; 95% CI: 0.56 to 0.90) were associated with lower odds of malnutrition.ConclusionsIn this large, representative community-based survey, there was a considerable pneumonia and malnutrition morbidity burden. We noted challenges in the diagnosis of Integrated Management of Childhood Illness-defined pneumonia in this context.
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| 15. |
- Schael, S, et al.
(författare)
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Precision electroweak measurements on the Z resonance
- 2006
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Ingår i: Physics Reports. - : Elsevier BV. - 0370-1573 .- 1873-6270. ; 427:5-6, s. 257-454
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Forskningsöversikt (refereegranskat)abstract
- We report on the final electroweak measurements performed with data taken at the Z resonance by the experiments operating at the electron-positron colliders SLC and LEP. The data consist of 17 million Z decays accumulated by the ALEPH, DELPHI, L3 and OPAL experiments at LEP, and 600 thousand Z decays by the SLID experiment using a polarised beam at SLC. The measurements include cross-sections, forward-backward asymmetries and polarised asymmetries. The mass and width of the Z boson, m(Z) and Gamma(Z), and its couplings to fermions, for example the p parameter and the effective electroweak mixing angle for leptons, are precisely measured: m(Z) = 91.1875 +/- 0.0021 GeV, Gamma(Z) = 2.4952 +/- 0.0023 GeV, rho(l) = 1.0050 +/- 0.0010, sin(2)theta(eff)(lept) = 0.23153 +/- 0.00016. The number of light neutrino species is determined to be 2.9840 +/- 0.0082, in agreement with the three observed generations of fundamental fermions. The results are compared to the predictions of the Standard Model (SM). At the Z-pole, electroweak radiative corrections beyond the running of the QED and QCD coupling constants are observed with a significance of five standard deviations, and in agreement with the Standard Model. Of the many Z-pole measurements, the forward-backward asymmetry in b-quark production shows the largest difference with respect to its SM expectation, at the level of 2.8 standard deviations. Through radiative corrections evaluated in the framework of the Standard Model, the Z-pole data are also used to predict the mass of the top quark, m(t) = 173(+10)(+13) GeV, and the mass of the W boson, m(W) = 80.363 +/- 0.032 GeV. These indirect constraints are compared to the direct measurements, providing a stringent test of the SM. Using in addition the direct measurements of m(t) and m(W), the mass of the as yet unobserved SM Higgs boson is predicted with a relative uncertainty of about 50% and found to be less than 285 GeV at 95% confidence level. (c) 2006 Elsevier B.V. All rights reserved.
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