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Sökning: WFRF:(Maier RF)

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  • Abel, I, et al. (författare)
  • Overview of the JET results with the ITER-like wall
  • 2013
  • Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 53:10, s. 104002-
  • 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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  • Romanelli, F, et al. (författare)
  • Overview of the JET results
  • 2011
  • Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 51:9
  • 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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  • Bonamy, AKE, et al. (författare)
  • Patent Ductus Arteriosus Treatment in Very Preterm Infants: A European Population-Based Cohort Study (EPICE) on Variation and Outcomes
  • 2017
  • Ingår i: Neonatology. - : S. Karger AG. - 1661-7819 .- 1661-7800. ; 111:4, s. 367-375
  • Tidskriftsartikel (refereegranskat)abstract
    • <b><i>Background:</i></b> Spontaneous closure of patent ductus arteriosus (PDA) occurs frequently in very preterm infants and despite the lack of evidence for treatment benefits, treatment for PDA is common in neonatal medicine. <b><i>Objectives:</i></b> The aim of this work was to study regional variations in PDA treatment in very preterm infants (≤31 weeks of gestation), its relation to differences in perinatal characteristics, and associations with bronchopulmonary dysplasia (BPD) and survival without major neonatal morbidity. <b><i>Methods:</i></b> This was a population-based cohort study in 19 regions in 11 European countries conducted during 2011 and 2012. A total of 6,896 infants with data on PDA treatment were included. The differences in infant characteristics were studied across regions using a propensity score derived from perinatal risk factors for PDA treatment. The primary outcomes were a composite of BPD or death before 36 weeks postmenstrual age, or survival without major neonatal morbidity. <b><i>Results:</i></b> The proportion of PDA treatment varied from 10 to 39% between regions (<i>p</i> < 0.001), and this difference could not be explained by differences in perinatal characteristics. The regions were categorized according to a low (<15%, <i>n</i> = 6), medium (15-25%, <i>n</i> = 9), or high (>25%, <i>n</i> = 4) proportion of PDA treatment. Infants treated for PDA, compared to those not treated, were at higher risk of BPD or death in all regions, with an overall propensity score adjusted risk ratio of 1.33 (95% confidence interval 1.18-1.51). Survival without major neonatal morbidity was not related to PDA treatment. <b><i>Conclusions:</i></b> PDA treatment varies largely across Europe without associated variations in perinatal characteristics or neonatal outcomes. This finding calls for more uniform guidance for PDA diagnosis and treatment in very preterm infants.
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  • Bonamy, AKE, et al. (författare)
  • Wide variation in severe neonatal morbidity among very preterm infants in European regions
  • 2019
  • Ingår i: Archives of disease in childhood. Fetal and neonatal edition. - : BMJ. - 1468-2052 .- 1359-2998. ; 104:1, s. F36-F45
  • Tidskriftsartikel (refereegranskat)abstract
    • To investigate the variation in severe neonatal morbidity among very preterm (VPT) infants across European regions and whether morbidity rates are higher in regions with low compared with high mortality rates.DesignArea-based cohort study of all births before 32 weeks of gestational age.Setting16 regions in 11 European countries in 2011/2012.PatientsSurvivors to discharge from neonatal care (n=6422).Main outcome measuresSevere neonatal morbidity was defined as intraventricular haemorrhage grades III and IV, cystic periventricular leukomalacia, surgical necrotizing enterocolitis and retinopathy of prematurity grades ≥3. A secondary outcome included severe bronchopulmonary dysplasia (BPD), data available in 14 regions. Common definitions for neonatal morbidities were established before data abstraction from medical records. Regional severe neonatal morbidity rates were correlated with regional in-hospital mortality rates for live births after adjustment on maternal and neonatal characteristics.Results10.6% of survivors had a severe neonatal morbidity without severe BPD (regional range 6.4%–23.5%) and 13.8% including severe BPD (regional range 10.0%–23.5%). Adjusted inhospital mortality was 13.7% (regional range 8.4%–18.8%). Differences between regions remained significant after consideration of maternal and neonatal characteristics (P<0.001) and severe neonatal morbidity rates were not correlated with mortality rates (P=0.50).ConclusionSevere neonatal morbidity rates for VPT survivors varied widely across European regions and were independent of mortality rates.
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  • Cuttini, M, et al. (författare)
  • Breastfeeding outcomes in European NICUs: impact of parental visiting policies
  • 2019
  • Ingår i: Archives of disease in childhood. Fetal and neonatal edition. - : BMJ. - 1468-2052 .- 1359-2998. ; 104:2, s. F151-
  • Tidskriftsartikel (refereegranskat)abstract
    • The documented benefits of maternal milk for very preterm infants have raised interest in hospital policies that promote breastfeeding. We investigated the hypothesis that more liberal parental policies are associated with increased breastfeeding at discharge from the neonatal unit.DesignProspective area-based cohort study.SettingNeonatal intensive care units (NICUs) in 19 regions of 11 European countries.PatientsAll very preterm infants discharged alive in participating regions in 2011–2012 after spending >70% of their hospital stay in the same NICU (n=4407).Main outcome measuresWe assessed four feeding outcomes at hospital discharge: any and exclusive maternal milk feeding, independent of feeding method; any and exclusive direct breastfeeding, defined as sucking at the breast. We computed a neonatal unit Parental Presence Score (PPS) based on policies regarding parental visiting in the intensive care area (range 1–10, with higher values indicating more liberal policies), and we used multivariable multilevel modified Poisson regression analysis to assess the relation between unit PPS and outcomes.ResultsPolicies regarding visiting hours, duration of visits and possibility for parents to stay during medical rounds and spend the night in unit differed within and across countries. After adjustment for potential confounders, infants cared for in units with liberal parental policies (PPS≥7) were about twofold significantly more likely to be discharged with exclusive maternal milk feeding and exclusive direct breastfeeding.ConclusionUnit policies promoting parental presence and involvement in care may increase the likelihood of successful breastfeeding at discharge for very preterm infants.
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  • El Rafei, R, et al. (författare)
  • Postnatal growth restriction and neurodevelopment at 5 years of age: a European extremely preterm birth cohort study
  • 2023
  • Ingår i: Archives of disease in childhood. Fetal and neonatal edition. - : BMJ. - 1468-2052 .- 1359-2998. ; 108:5, s. F492-F498
  • Tidskriftsartikel (refereegranskat)abstract
    • To investigate whether extrauterine growth restriction (EUGR) during the neonatal hospitalisation by sex among extremely preterm (EPT) infants is associated with cerebral palsy (CP) and cognitive and motor abilities at 5 years of age.Study designPopulation-based cohort of births <28 weeks of gestation with data from obstetric and neonatal records and parental questionnaires and clinical assessments at 5 years of age.Setting11 European countries.Patients957 EPT infants born in 2011–2012.Main outcomesEUGR at discharge from the neonatal unit was defined as (1) the difference between Z-scores at birth and discharge with <−2 SD as severe, −2 to −1 SD as moderate using Fenton’s growth charts (Fenton) and (2) average weight-gain velocity using Patel’s formula in grams (g) per kilogram per day (Patel) with <11.2 g (first quartile) as severe, 11.2–12.5 g (median) as moderate. Five-year outcomes were: a CP diagnosis, intelligence quotient (IQ) using the Wechsler Preschool and Primary Scales of Intelligence tests and motor function using the Movement Assessment Battery for Children, second edition.Results40.1% and 33.9% children were classified as having moderate and severe EUGR, respectively, by Fenton and 23.8% and 26.3% by Patel. Among children without CP, those with severe EUGR had lower IQ than children without EUGR (−3.9 points, 95% Confidence Interval (CI)=−7.2 to −0.6 for Fenton and −5.0 points, 95% CI=−8.2 to −1.8 for Patel), with no interaction by sex. No significant associations were observed between motor function and CP.ConclusionsSevere EUGR among EPT infants was associated with decreased IQ at 5 years of age.
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  • El Rafei, R, et al. (författare)
  • Variation in very preterm extrauterine growth in a European multicountry cohort
  • 2021
  • Ingår i: Archives of disease in childhood. Fetal and neonatal edition. - : BMJ. - 1468-2052 .- 1359-2998. ; 106:3, s. F316-F323
  • Tidskriftsartikel (refereegranskat)abstract
    • Extrauterine growth restriction (EUGR) among very preterm infants is related to poor neurodevelopment, but lack of consensus on EUGR measurement constrains international research. Our aim was to compare EUGR prevalence in a European very preterm cohort using commonly used measures.DesignPopulation-based observational study.Setting19 regions in 11 European countries.Patients6792 very preterm infants born before 32 weeks’ gestational age (GA) surviving to discharge.Main outcome measuresWe investigated two measures based on discharge-weight percentiles with (1) Fenton and (2) Intergrowth (IG) charts and two based on growth velocity (1) birth weight and discharge-weight Z-score differences using Fenton charts and (2) weight-gain velocity using Patel’s model. We estimated country-level relative risks of EUGR adjusting for maternal and neonatal characteristics and associations with population differences in healthy newborn size, measured by mean national birth weight at 40 weeks’ GA.ResultsAbout twofold differences in EUGR prevalence were observed between countries for all indicators and these persisted after case-mix adjustment. Discharge weight <10th percentile using Fenton charts varied from 24% (Sweden) to 60% (Portugal) and using IG from 13% (Sweden) to 43% (Portugal), while low weight-gain velocity ranged from 35% (Germany) to 62% (UK). Mean term birth weight strongly correlated with both percentile-based measures (Spearman’s rho=−0.90 Fenton, −0.84 IG, p<0.01), but not Patel’s weight-gain velocity (rho: −0.38, p=0.25).ConclusionsVery preterm infants have a high prevalence of EUGR, with wide variations between countries in Europe. Variability associated with mean term birth weight when using common postnatal growth charts complicates international benchmarking.
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  • Lorthe, E, et al. (författare)
  • Unit policies regarding tocolysis after preterm premature rupture of membranes: association with latency, neonatal and 2-year outcomes (EPICE cohort)
  • 2020
  • Ingår i: Scientific reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 10:1, s. 9535-
  • Tidskriftsartikel (refereegranskat)abstract
    • After preterm premature rupture of membranes (PPROM), antibiotics and antenatal steroids are effective evidence-based interventions, but the use of tocolysis is controversial. We investigated whether a unit policy of tocolysis use after PPROM is associated with prolonged gestation and improved outcomes for very preterm infants in units that systematically use these other evidence-based treatments. From the prospective, observational, population-based EPICE cohort study (all very preterm births in 19 regions from 11 European countries, 2011–2012), we included 607 women with a singleton pregnancy and PPROM at 24–29 weeks’ gestation, of whom 101, 195 and 311 were respectively managed in 17, 32 and 45 units with no-use, restricted and liberal tocolysis policies for PPROM. The association between unit policies and outcomes (early-onset sepsis, survival at discharge, survival at discharge without severe morbidity and survival at two years without gross motor impairment) was investigated using three-level random-intercept logistic regression models, showing no differences in neonatal or two-year outcomes by unit policy. Moreover, there was no association between unit policies and prolongation of gestation in a multilevel survival analysis. Compared to a unit policy of no-use of tocolysis after PPROM, a liberal or restricted policy is not associated with improved obstetric, neonatal or two-year outcomes.
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  • Seppanen, AV, et al. (författare)
  • Follow-up after very preterm birth in Europe
  • 2022
  • Ingår i: Archives of disease in childhood. Fetal and neonatal edition. - : BMJ. - 1468-2052 .- 1359-2998. ; 107:1, s. 113-114
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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  • Zeitlin, J, et al. (författare)
  • Authors' reply to Page and Rafi
  • 2016
  • Ingår i: BMJ (Clinical research ed.). - : BMJ. - 1756-1833. ; 354, s. i4671-
  • Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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  • Zeitlin, J, et al. (författare)
  • Priorities for collaborative research using very preterm birth cohorts
  • 2020
  • Ingår i: Archives of disease in childhood. Fetal and neonatal edition. - : BMJ. - 1468-2052 .- 1359-2998. ; 105:5, s. 538-544
  • Tidskriftsartikel (refereegranskat)abstract
    • To develop research priorities on the consequences of very preterm (VPT) birth for the RECAP Preterm platform which brings together data from 23 European VPT birth cohorts.Design and settingThis study used a two-round modified Delphi consensus process. Round 1 was based on 28 research themes related to childhood outcomes (<12 years) derived from consultations with cohort researchers. An external panel of multidisciplinary stakeholders then ranked their top 10 themes and provided comments. In round 2, panel members provided feedback on rankings and on new themes suggested in round 1.ResultsOf 71 individuals contacted, 64 (90%) participated as panel members comprising obstetricians, neonatologists, nurses, general and specialist paediatricians, psychologists, physiotherapists, parents, adults born preterm, policy makers and epidemiologists from 17 countries. All 28 initial themes were ranked in the top 10 by at least six panel members. Highest ranking themes were: education (73% of panel members' top 10 choices); care and outcomes of extremely preterm births, including ethical decisions (63%); growth and nutrition (60%); emotional well-being and social inclusion (55%); parental stress (55%) and impact of social circumstances on outcomes (52%). Highest ranking themes were robust across panel members classified by background. 15 new themes had at least 6 top 10 endorsements in round 2.ConclusionsThis study elicited a broad range of research priorities on the consequences of VPT birth, with good consensus on highest ranks between stakeholder groups. Several highly ranked themes focused on the socioemotional needs of children and parents, which have been less studied.
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