| 1. |
- Murari, A., et al.
(författare)
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A control oriented strategy of disruption prediction to avoid the configuration collapse of tokamak reactors
- 2024
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Ingår i: Nature Communications. - 2041-1723 .- 2041-1723. ; 15:1
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Tidskriftsartikel (refereegranskat)abstract
- The objective of thermonuclear fusion consists of producing electricity from the coalescence of light nuclei in high temperature plasmas. The most promising route to fusion envisages the confinement of such plasmas with magnetic fields, whose most studied configuration is the tokamak. Disruptions are catastrophic collapses affecting all tokamak devices and one of the main potential showstoppers on the route to a commercial reactor. In this work we report how, deploying innovative analysis methods on thousands of JET experiments covering the isotopic compositions from hydrogen to full tritium and including the major D-T campaign, the nature of the various forms of collapse is investigated in all phases of the discharges. An original approach to proximity detection has been developed, which allows determining both the probability of and the time interval remaining before an incoming disruption, with adaptive, from scratch, real time compatible techniques. The results indicate that physics based prediction and control tools can be developed, to deploy realistic strategies of disruption avoidance and prevention, meeting the requirements of the next generation of devices.
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| 2. |
- Joffrin, E., et al.
(författare)
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Overview of the JET preparation for deuterium-tritium operation with the ITER like-wall
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- For the past several years, the JET scientific programme (Pamela et al 2007 Fusion Eng. Des. 82 590) has been engaged in a multi-campaign effort, including experiments in D, H and T, leading up to 2020 and the first experiments with 50%/50% D-T mixtures since 1997 and the first ever D-T plasmas with the ITER mix of plasma-facing component materials. For this purpose, a concerted physics and technology programme was launched with a view to prepare the D-T campaign (DTE2). This paper addresses the key elements developed by the JET programme directly contributing to the D-T preparation. This intense preparation includes the review of the physics basis for the D-T operational scenarios, including the fusion power predictions through first principle and integrated modelling, and the impact of isotopes in the operation and physics of D-T plasmas (thermal and particle transport, high confinement mode (H-mode) access, Be and W erosion, fuel recovery, etc). This effort also requires improving several aspects of plasma operation for DTE2, such as real time control schemes, heat load control, disruption avoidance and a mitigation system (including the installation of a new shattered pellet injector), novel ion cyclotron resonance heating schemes (such as the three-ions scheme), new diagnostics (neutron camera and spectrometer, active Alfven eigenmode antennas, neutral gauges, radiation hard imaging systems...) and the calibration of the JET neutron diagnostics at 14 MeV for accurate fusion power measurement. The active preparation of JET for the 2020 D-T campaign provides an incomparable source of information and a basis for the future D-T operation of ITER, and it is also foreseen that a large number of key physics issues will be addressed in support of burning plasmas.
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| 6. |
- Adams, C., et al.
(författare)
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Validation of ACE and OSIRIS ozone and NO2 measurements using ground-based instruments at 80 degrees N
- 2012
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Ingår i: Atmospheric Measurement Techniques. - : Copernicus GmbH. - 1867-1381 .- 1867-8548. ; 5:5, s. 927-953
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Tidskriftsartikel (refereegranskat)abstract
- The Optical Spectrograph and Infra-Red Imager System (OSIRIS) and the Atmospheric Chemistry Experiment (ACE) have been taking measurements from space since 2001 and 2003, respectively. This paper presents intercomparisons between ozone and NO2 measured by the ACE and OSIRIS satellite instruments and by ground-based instruments at the Polar Environment Atmospheric Research Laboratory (PEARL), which is located at Eureka, Canada (80A degrees N, 86A degrees W) and is operated by the Canadian Network for the Detection of Atmospheric Change (CANDAC). The ground-based instruments included in this study are four zenith-sky differential optical absorption spectroscopy (DOAS) instruments, one Bruker Fourier transform infrared spectrometer (FTIR) and four Brewer spectrophotometers. Ozone total columns measured by the DOAS instruments were retrieved using new Network for the Detection of Atmospheric Composition Change (NDACC) guidelines and agree to within 3.2%. The DOAS ozone columns agree with the Brewer spectrophotometers with mean relative differences that are smaller than 1.5%. This suggests that for these instruments the new NDACC data guidelines were successful in producing a homogenous and accurate ozone dataset at 80A degrees N. Satellite 14-52 km ozone and 17-40 km NO2 partial columns within 500 km of PEARL were calculated for ACE-FTS Version 2.2 (v2.2) plus updates, ACE-FTS v3.0, ACE-MAESTRO (Measurements of Aerosol Extinction in the Stratosphere and Troposphere Retrieved by Occultation) v1.2 and OSIRIS SaskMART v5.0x ozone and Optimal Estimation v3.0 NO2 data products. The new ACE-FTS v3.0 and the validated ACE-FTS v2.2 partial columns are nearly identical, with mean relative differences of 0.0 +/- 0.2% and -0.2 +/- 0.1% for v2.2 minus v3.0 ozone and NO2, respectively. Ozone columns were constructed from 14-52 km satellite and 0-14 km ozonesonde partial columns and compared with the ground-based total column measurements. The satellite-plus-sonde measurements agree with the ground-based ozone total columns with mean relative differences of 0.1-7.3%. For NO2, partial columns from 17 km upward were scaled to noon using a photochemical model. Mean relative differences between OSIRIS, ACE-FTS and ground-based NO2 measurements do not exceed 20%. ACE-MAESTRO measures more NO2 than the other instruments, with mean relative differences of 25-52%. Seasonal variation in the differences between NO2 partial columns is observed, suggesting that there are systematic errors in the measurements and/or the photochemical model corrections. For ozone spring-time measurements, additional coincidence criteria based on stratospheric temperature and the location of the polar vortex were found to improve agreement between some of the instruments. For ACE-FTS v2.2 minus Bruker FTIR, the 2007-2009 spring-time mean relative difference improved from -5.0 +/- 0.4% to -3.1 +/- 0.8% with the dynamical selection criteria. This was the largest improvement, likely because both instruments measure direct sunlight and therefore have well-characterized lines-of-sight compared with scattered sunlight measurements. For NO2, the addition of a +/- 1A degrees latitude coincidence criterion improved spring-time intercomparison results, likely due to the sharp latitudinal gradient of NO2 during polar sunrise. The differences between satellite and ground-based measurements do not show any obvious trends over the missions, indicating that both the ACE and OSIRIS instruments continue to perform well.
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| 7. |
- Navarrete-Miguel, M., et al.
(författare)
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Quantum chemistry of the excited state : Recent trends in methods developments and applications
- 2019
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Ingår i: Photochemistry. - Cambridge : Royal Society of Chemistry. - 1465-1947. - 9781788013369 ; , s. 28-77
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Bokkapitel (refereegranskat)abstract
- Advances (2016-2017) in Quantum Chemistry of the Excited State (QCEX) are presented in this book chapter focusing firstly on developments of methodology and excited-state reaction-path computational strategies and secondly on the applications of QCEX to study light-matter interaction in distinct fields of biology, (nano)-technology, medicine and the environment. We highlight in this contribution developments of static and dynamic electron-correlation methods and methodological approaches to determine dynamical properties, recent examples of the roles of conical intersections, novel DNA spectroscopy and photochemistry findings, photo-sensitisation mechanisms in biological structures and the current knowledge on chemi-excitation mechanisms that give rise to light emission (in the chemiluminescence and bioluminescence phenomena).
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| 10. |
- Khankeh, H, et al.
(författare)
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Comparison of vaccine hesitancy during the low and high points of COVID-19 in a population under international sanctions: A longitudinal mixed-methods study in Iran
- 2023
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Ingår i: Frontiers in public health. - : Frontiers Media SA. - 2296-2565. ; 10, s. 958899-
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Tidskriftsartikel (refereegranskat)abstract
- Along with the challenges of COVID-19 vaccine supply in low-income countries, vaccine hesitancy was another problem for the health system. The aim of this study was to deeply understand the challenges of vaccine acceptance, the vaccination process, and to compare the affecting vaccine acceptance in the high and low points of the epidemic in Iran.MethodsIn the qualitative part of this mixed-methods study, content analysis was used to investigate experiences and perceptions about COVID-19 vaccination in four groups. In the quantitative study, in March 2021 (low point), and on August 1, 2021 (high point), two population-based cross-sectional studies were performed in Tehran and its rural, with sample sizes of 1,200 and 1,872 people aged over 18 years, respectively. Multinomial (polytomous) logistic regression was used to determine the factors affecting hesitation and unwillingness to receive the vaccine.ResultsDisbelief in vaccine safety, vaccine distrust, ignorance and confusion, and inadequate facilities were the common reasons extracted in the two qualitative studies. At the low and high points of the epidemic, vaccine acceptance was 83.6% (95% CI: 81.3–85.9) and 65.8% (95% CI: 65.8–71.0), respectively. Residence in rural areas, (Odds Ratio: 0.44, p = 0.001), being a student (Odds Ratio: 0.41, p = 0.011), housewives (Odds Ratio: 0.63, p = 0.033), illiteracy (Odds Ratio: 4.44, p = 0.001), and having an underlying disease (Odds Ratio: 4.44, p = 0.001) were factors affecting on vaccine acceptance.DiscussionCounter-intuitively, acceptance did not increase at the peak of epidemic. The presence of obstacles, such as increased distrust in the effectiveness of vaccines due to the occurrence of multiple peaks in different vaccinated countries, as well as the influence of the media, anti-vaccine campaigns, and lack of proper communication about risks caused more hesitation. More investigation to understand how people accept or reject vaccine and its long term consequences is recommended.
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| 13. |
- Shokri, Omid, et al.
(författare)
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Gender and academic stress : a model for moderating effects in cultural context
- 2013
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Ingår i: Journal of Behavioral Science. - : Srinakharinwirot University/Behavioral Science Research Institute. - 1686-1442. ; 7:1, s. 35-42
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Tidskriftsartikel (refereegranskat)abstract
- Introduction:This study examined the moderating effect of cultural contexts in the relationship between gender and academic stress among male and female Iranian and Swedish university students.Method:The Academic Stress Questionnaire (ASQ) was administered to 212 students (112 Iranian (32 male and 78 female) and 100 Swedish (29 male and 71 female)). Linear Regression analysis was used for data analysis.Results:The results of regression analysis indicated that there was a significant positive correlation between gender and academic stress among Iranian and Swedish students. Results also indicated that the relationship between gender and academic stress was not moderated by cultural context. However, gender was found to be a strong predictor for academic stress for Iranian students in comparison with Swedish ones.Conclusion:Although these findings showed that the relationship between gender and academic stress was not oderated by cultural context, obvious differences in predictive values of standardized regression of academic stress by gender among Iranian and Swedish students support theoretical assumptions underlying transactional theory of stress and expectation theory of sexual role.
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| 14. |
- Tohry, A., et al.
(författare)
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Variable importance assessments of an innovative industrial-scale magnetic separator for processing of iron ore tailings
- 2020
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Ingår i: Mineral Processing and Extractive Metallurgy. - : Taylor & Francis. - 2572-6641 .- 2572-665X. ; 131:2, s. 122-129
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Tidskriftsartikel (refereegranskat)abstract
- Reprocessing of iron ore tailings (IOTs) and extracting recoverable valuable iron oxides will become increasingly financially attractive for mining companies and also may reduce environmental problems. Using databases built based on long term monitoring of units installed on plants to control the operational conditions to generate artificial intelligence models can decrease the cost of reprocessing operations Although some investigations have been focused on the reprocessing of IOTs, several challenges still remain which need to be addressed, especially for fine particles. SLon®, has developed a pulsating high gradient magnetic separator for the processing of fine iron oxides. However, there has been no systematic optimisation and variable assessments for SLon® operating variables to examine their effects on metallurgical responses (separation efficiency) on the industrial scale. This study addressed these drawbacks by linear (Pearson correlation) and non-linear (random forest) variable importance measurements (VIM) through an industrial SLon® installation.
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| 15. |
- Yaghoobi, H, et al.
(författare)
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The role of the mothers' sense of coherence in predicting dental caries risk in children
- 2022
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Ingår i: Community Dental Health. - 0265-539X. ; 39:3, s. 206-210
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Individuals with a stronger sense of coherence (SOC) often show healthier behaviors. As parents, especially mothers, are behavioral role models for their children, this study aimed to explore the role of the mothers' SOC in prediction of the risk of dental caries in a sample of children aged 11-12 years old.DESIGN: Cross-sectional study with 173 mother-child pairs enrolled by multi-stage sampling from four public schools in Torbat-e-Heydarieh, Iran. The data were obtained, using a demographic-health information sheet and the SOC-13 scale. Dental examinations of children were performed using the decay, missing and filled teeth index for primary (dmft) and permanent teeth (DMFT). Poisson regression analyses estimated the role of the mothers' SOC in predicting the relative risk (RR) of children's dental caries.RESULTS: Mean dmft and DMFT were 3.4 ± 3.1 and 2.7 ± 2.9 respectively (medium severity). After controlling for demographic and health variables in regression models, greater maternal SOC indicated a protective effect against dental caries in primary (RR: 0.96; 95% CI:0.96-0-97) and permanent teeth (RR: 0.96; 95% CI: 0.95-0.97) of their children.CONCLUSIONS: With greater maternal SOC, the risk of children's dental caries decreased. Whilst this relationship was not as strong as in previous studies in other countries, it can be a platform for further research and perhaps planning to identify children who are at a greater risk of dental caries before starting dental examinations in schools.
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