| 1. |
- Stroth, U., et al.
(författare)
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Progress from ASDEX Upgrade experiments in preparing the physics basis of ITER operation and DEMO scenario development
- 2022
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 62:4
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Tidskriftsartikel (refereegranskat)abstract
- An overview of recent results obtained at the tokamak ASDEX Upgrade (AUG) is given. A work flow for predictive profile modelling of AUG discharges was established which is able to reproduce experimental H-mode plasma profiles based on engineering parameters only. In the plasma center, theoretical predictions on plasma current redistribution by a dynamo effect were confirmed experimentally. For core transport, the stabilizing effect of fast ion distributions on turbulent transport is shown to be important to explain the core isotope effect and improves the description of hollow low-Z impurity profiles. The L-H power threshold of hydrogen plasmas is not affected by small helium admixtures and it increases continuously from the deuterium to the hydrogen level when the hydrogen concentration is raised from 0 to 100%. One focus of recent campaigns was the search for a fusion relevant integrated plasma scenario without large edge localised modes (ELMs). Results from six different ELM-free confinement regimes are compared with respect to reactor relevance: ELM suppression by magnetic perturbation coils could be attributed to toroidally asymmetric turbulent fluctuations in the vicinity of the separatrix. Stable improved confinement mode plasma phases with a detached inner divertor were obtained using a feedback control of the plasma β. The enhanced D α H-mode regime was extended to higher heating power by feedback controlled radiative cooling with argon. The quasi-coherent exhaust regime was developed into an integrated scenario at high heating power and energy confinement, with a detached divertor and without large ELMs. Small ELMs close to the separatrix lead to peeling-ballooning stability and quasi continuous power exhaust. Helium beam density fluctuation measurements confirm that transport close to the separatrix is important to achieve the different ELM-free regimes. Based on separatrix plasma parameters and interchange-drift-Alfvén turbulence, an analytic model was derived that reproduces the experimentally found important operational boundaries of the density limit and between L- and H-mode confinement. Feedback control for the X-point radiator (XPR) position was established as an important element for divertor detachment control. Stable and detached ELM-free phases with H-mode confinement quality were obtained when the XPR was moved 10 cm above the X-point. Investigations of the plasma in the future flexible snow-flake divertor of AUG by means of first SOLPS-ITER simulations with drifts activated predict beneficial detachment properties and the activation of an additional strike point by the drifts.
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| 2. |
- Meyer, H.F., et al.
(författare)
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Overview of physics studies on ASDEX Upgrade
- 2019
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 1741-4326 .- 0029-5515. ; 59:11
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Forskningsöversikt (refereegranskat)abstract
- The ASDEX Upgrade (AUG) programme, jointly run with the EUROfusion MST1 task force, continues to significantly enhance the physics base of ITER and DEMO. Here, the full tungsten wall is a key asset for extrapolating to future devices. The high overall heating power, flexible heating mix and comprehensive diagnostic set allows studies ranging from mimicking the scrape-off-layer and divertor conditions of ITER and DEMO at high density to fully non-inductive operation (q 95 = 5.5, ) at low density. Higher installed electron cyclotron resonance heating power 6 MW, new diagnostics and improved analysis techniques have further enhanced the capabilities of AUG. Stable high-density H-modes with MW m-1 with fully detached strike-points have been demonstrated. The ballooning instability close to the separatrix has been identified as a potential cause leading to the H-mode density limit and is also found to play an important role for the access to small edge-localized modes (ELMs). Density limit disruptions have been successfully avoided using a path-oriented approach to disruption handling and progress has been made in understanding the dissipation and avoidance of runaway electron beams. ELM suppression with resonant magnetic perturbations is now routinely achieved reaching transiently . This gives new insight into the field penetration physics, in particular with respect to plasma flows. Modelling agrees well with plasma response measurements and a helically localised ballooning structure observed prior to the ELM is evidence for the changed edge stability due to the magnetic perturbations. The impact of 3D perturbations on heat load patterns and fast-ion losses have been further elaborated. Progress has also been made in understanding the ELM cycle itself. Here, new fast measurements of and E r allow for inter ELM transport analysis confirming that E r is dominated by the diamagnetic term even for fast timescales. New analysis techniques allow detailed comparison of the ELM crash and are in good agreement with nonlinear MHD modelling. The observation of accelerated ions during the ELM crash can be seen as evidence for the reconnection during the ELM. As type-I ELMs (even mitigated) are likely not a viable operational regime in DEMO studies of 'natural' no ELM regimes have been extended. Stable I-modes up to have been characterised using -feedback. Core physics has been advanced by more detailed characterisation of the turbulence with new measurements such as the eddy tilt angle - measured for the first time - or the cross-phase angle of and fluctuations. These new data put strong constraints on gyro-kinetic turbulence modelling. In addition, carefully executed studies in different main species (H, D and He) and with different heating mixes highlight the importance of the collisional energy exchange for interpreting energy confinement. A new regime with a hollow profile now gives access to regimes mimicking aspects of burning plasma conditions and lead to nonlinear interactions of energetic particle modes despite the sub-Alfvénic beam energy. This will help to validate the fast-ion codes for predicting ITER and DEMO.
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| 3. |
- Bachmann, L., et al.
(författare)
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The role of systematics for understanding ecosystem functions: Proceedings of the Zoologica Scripta Symposium, Oslo, Norway, 25 August 2022
- 2023
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Ingår i: Zoologica Scripta. - : Wiley. - 0300-3256 .- 1463-6409. ; 52:3, s. 187-214
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Tidskriftsartikel (refereegranskat)abstract
- On 25 August 2022, the Zoologica Scripta - An International Journal of Systematic Zoology and the Norwegian Academy of Sciences and Letters arranged a symposium entitled 'The role of systematics for understanding ecosystem functions' in the Academy's premises in Oslo, Norway. The symposium aimed at offering a forum for exploring and discussing trends and future developments in the field of systematics. Eleven international experts contributed expertise on various issues related to global challenges, such as biodiversity assessments, databases, cutting-edge analysis tools, and the consequences of the taxonomic impediment. Here, we compiled a multi-author proceedings paper of the symposium contributions that are arranged in chapters and presents the content and the key conclusions of the majority of the presentations.
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| 4. |
- Carel, RH, et al.
(författare)
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Exposure to asbestos and lung and pleural cancer mortality among pulp and paper industry workers
- 2002
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Ingår i: Journal of Occupational and Environmental Medicine. - 1076-2752 .- 1536-5948. ; 44:6, s. 579-584
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Tidskriftsartikel (refereegranskat)abstract
- We studied the mortality from lung and pleural cancers in a cohort of 62, 937 male workers employed for at least 1 year in the pulp and paper industry in 13 countries during 1945 to 1996. Mill departments were classified according to probability and level of exposure to asbestos on the basis of available dust measurements and mill-specific information on exposure circumstances. Thirty-six percent of workers were classified as ever exposed to asbestos. Standardized mortality ratios of lung cancer were 0.99 (95 % confidence interval [CI], 0.90 to 1.08) among unexposed and 1.00 (95 % CI, 0.90 to 1.11) among ever exposed workers. The number of pleural cancer deaths among unexposed workers was 10, that among exposed workers was 14, most of which occurred among maintenance workers. In internal analyses, a trend in mortality from either neoplasm was suggested for estimated cumulative exposure to asbestos, weighted for the individual probability of exposure within the department and for duration of exposure (relative risk for lung cancer for 0.78+ f/cc-years, as compared with = 0.01 f/cc-years: 1.44, 95 % CI, 0.85 to 2.45, corresponding relative risk for pleural cancer: 2.43, 95% CI, 0.43 to 13.63). Despite a possible nondifferential misclassification of exposure and outcome, this study suggests that the carcinogenic effect of asbestos can be detected among workers employed in industries such as the pulp and paper industry, in which it is not considered to be a major hazard.
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| 5. |
- McLean, D., et al.
(författare)
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Cancer mortality in workers exposed to organochlorine compounds in the pulp and paper industry : An international collaborative study
- 2006
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Ingår i: Journal of Environmental Health Perspectives. - : Environmental Health Perspectives. - 0091-6765 .- 1552-9924. ; 114:7, s. 1007-1012
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Tidskriftsartikel (refereegranskat)abstract
- The objective of this study was to evaluate cancer mortality in pulp and paper industry workers exposed to chlorinated organic compounds. We assembled a multinational cohort of workers employed between 1920 and 1996 in 11 countries. Exposure to both volatile and nonvolatile organochlorine compounds was estimated at the department level using an exposure matrix. We conducted a standardized mortality ratio (SMR) analysis based on age and calendar-period-specific national mortality rates and a Poisson regression analysis. The study population consisted of 60,468 workers. Workers exposed to volatile organochlorines experienced a deficit of all-cause [SMR = 0.91, 95% confidence interval (CI), 0.89-0.93] and all-cancer (SMR = 0.93, 95% CI, 0.89-0.97) mortality, with no evidence of increased risks for any cancer of a priori interest. There was a weak, but statistically significant, trend of increasing risk of all-cancer mortality with increasing weighted cumulative exposure. A similar deficit in all-cause (SMR = 0.94, 95% CI, 0.91-0.96) and all-cancer (SMR = 0.94, 95% CI, 0.89-1.00) mortality was observed in those exposed to nonvolatile organochlorines. No excess risk was observed in cancers of a priori interest, although mortality from Hodgkin disease was elevated (SMR = 1.76, 95% CI, 1.02-2.82). In this study we found little evidence that exposure to organochlorines at the levels experienced in the pulp and paper industry is associated with an increased risk of cancer, apart from a weak but significant association between all-cancer mortality and weighted cumulative volatile organochlorine exposure.
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| 6. |
- Flores, H., et al.
(författare)
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Impact of climate change on Antarctic krill
- 2012
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Ingår i: Marine Ecology-Progress Series. - : Inter-Research Science Center. - 0171-8630 .- 1616-1599. ; 458, s. 1-19
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Tidskriftsartikel (refereegranskat)abstract
- Antarctic krill Euphausia superba (hereafter 'krill') occur in regions undergoing rapid environmental change, particularly loss of winter sea ice. During recent years, harvesting of krill has in creased, possibly enhancing stress on krill and Antarctic ecosystems. Here we review the overall impact of climate change on krill and Antarctic ecosystems, discuss implications for an ecosystem-based fisheries management approach and identify critical knowledge gaps. Sea ice decline, ocean warming and other environmental stressors act in concert to modify the abundance, distribution and life cycle of krill. Although some of these changes can have positive effects on krill, their cumulative impact is most likely negative. Recruitment, driven largely by the winter survival of larval krill, is probably the population parameter most susceptible to climate change. Predicting changes to krill populations is urgent, because they will seriously impact Antarctic ecosystems. Such predictions, however, are complicated by an intense inter-annual variability in recruitment success and krill abundance. To improve the responsiveness of the ecosystem-based management approach adopted by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR), critical knowledge gaps need to be filled. In addition to a better understanding of the factors influencing recruitment, management will require a better understanding of the resilience and the genetic plasticity of krill life stages, and a quantitative understanding of under-ice and benthic habitat use. Current precautionary management measures of CCAMLR should be maintained until a better understanding of these processes has been achieved. [GRAPHICS] .
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| 7. |
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| 8. |
- Trask, Catherine, et al.
(författare)
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More for the Money : Cost Efficiency in Trunk Posture Observation
- 2010
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Ingår i: Canadian Association for Research in Work and Health. - Toronto, Canada.
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Konferensbidrag (refereegranskat)abstract
- Objectives:In a climate of scarce research funds, cost-effective exposure assessment becomes more critical. There is a long-acknowledged tradeoff between precision and cost of exposure assessment methods (Winkel and Mathiassen, 1994) that is seldom quantified.The purpose of this study was to compare different sampling strategies for observed trunk posture and determinewhich is the most cost-effective.Knowing the price-performance tradeoffs of observational exposure assessment can help researchers make the most of limited funds.Methods(maximum 150 words)Trunk posture data was observed by trained experts during full work shifts on 126 workers in heavy industry, with repeated measures on 76% of workers. The observed percentage of time spent with trunk flexed more than 60 degrees was recorded and summarized for each work day using the Back-EST sampling method (Village et al 2009). A cost model was developed using previously published cost data (Trask et al 2007) to account for the costs of recruiting companies, workers, and making a full-shift observation of trunk posture. Precision was described in terms of the standard error of the group mean (SEM), using equations from Samuels (1985) that account for multiple measures within companies and workers. Changes in cost efficiency were calculated for sampling strategies employing different combinations of the following: 1-4 companies, 1-12 workers, and 1-4 measures per worker. The case of one recruited company is highlighted here as an example.Results:(maximum 100 words)The SEM declines steeply for the first few additional subjects, while further subjects increase costs considerably with no substantial improvements in precision. Adding repeated measures generally increased costs with smaller gains in precision. In a single-company example, measuring 6 subjects twice (12 measurements total) yields SEM = 0.76 and costs $3929. The same number of measurements can cost up to $4505 with 12 subjects and no repeats, improving the SEM to 0.75. However, increased cost does not always deliver gains in precision; an SEM of 0.76 can cost up to $5545 when 5 subjects are measured 4 times.Conclusions(maximum 100 words)The total number of measurements has been used as a metric for cost optimization in previous investigations (Lemasters et al 1996). However, an equal number of measurements can have different costs depending on how they are allocated due to recruitment costs. Such cost-efficiency information allows researchers to make informed decisions on the use of limited resources when designing ergonomic studies; either determining the maximum precision level that can be achieved for a given cost, or the minimum cost for a given level of precision.
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| 9. |
- Trask, Catherine, et al.
(författare)
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Price versus precision cost efficiency in trunk posture observation (Poster)
- 2010
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Konferensbidrag (refereegranskat)abstract
- Aims There is a long-acknowledged tradeoff between precision and cost of exposure assessment strategies (Winkel and Mathiassen, 1994), but a dearth of literature quantifying this tradeoff. This study compares different sampling strategies for trunk posture observation with respect to monetary costs and statistical efficiency. Methods Experts observed 126 workers in heavy industry during full work shifts, with repeated measures on 76% of workers. The observed percentage of time spent with trunk flexed more than 60 degrees was recorded and summarized for each work day using the Back-EST sampling method (Village et al 2009). A model of costs associated with the data sampling strategy was developed using previously published data (Trask et al 2007), accounting for the costs of recruiting companies and workers, and of observing full work shifts. Statistical performance was described as standard error of the mean (SEM). Post hoc, a selection of sampling strategies were simulated to demonstrate the empirical trade-off between cost and efficiency for different sampling strategies. Results: Figure 1 shows the family of curves resulting when 1 to 10 workers are measured 1 to 4 times within a single company. The SEM declines steeply for the first few additional subjects, while further subjects increase costs considerably with no substantial improvements in precision. Adding repeated measures generally increased costs with smaller gains in precision. Discussion/conclusions: This study informs design of posture observation sampling campaigns; the ‘mesh’ of sampling strategies in the figure demonstrates the maximum precision level that can be achieved for a given cost, as well as the minimum cost for a given level of precision. This allows researchers to make informed decisions on the use of limited resources when designing ergonomic studies
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