| 1. |
- Kanai, M, et al.
(författare)
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- 2023
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swepub:Mat__t
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| 2. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 3. |
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| 4. |
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| 5. |
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| 6. |
- 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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| 7. |
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| 8. |
- 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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| 9. |
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| 10. |
- 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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| 11. |
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| 12. |
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| 13. |
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| 14. |
- Beral, V., et al.
(författare)
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Ovarian cancer and smoking: individual participant meta-analysis including 28 114 women with ovarian cancer from 51 epidemiological studies
- 2012
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Ingår i: The Lancet Oncology. - 1474-5488. ; 13:9, s. 946-956
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Tidskriftsartikel (refereegranskat)abstract
- Background Smoking has been linked to mucinous ovarian cancer, but its effects on other ovarian cancer subtypes and on overall ovarian cancer risk are unclear, and the findings from most studies with relevant data are unpublished. To assess these associations, we review the published and unpublished evidence. Methods Eligible epidemiological studies were identified by electronic searches, review articles, and discussions with colleagues. Individual participant data for 28 114 women with and 94 942 without ovarian cancer from 51 epidemiological studies were analysed centrally, yielding adjusted relative risks (RRs) of ovarian cancer in smokers compared with never smokers. Findings After exclusion of studies with hospital controls, in which smoking could have affected recruitment, overall ovarian cancer incidence was only slightly increased in current smokers compared with women who had never smoked (RR 1.06, 95% CI 1.01-1.11, p=0.01). Of 17 641 epithelial cancers with specified histology, 2314 (13%) were mucinous, 2360 (13%) endometrioid, 969 (5%) clear-cell, and 9086 (52%) serous. Smoking-related risks varied substantially across these subtypes (p(heterogeneity)<0.0001). For mucinous cancers, incidence was increased in current versus never smokers (1.79, 95% CI 1.60-2.00, p<0.0001), but the increase was mainly in borderline malignant rather than in fully malignant tumours (2.25, 95% CI 1.91-2.65 vs 1.49, 1.28-1.73; p(heterogeneity)=0.01; almost half the mucinous tumours were only borderline malignant). Both endometrioid (0.81, 95% CI 0.72-0.92, p=0.001) and clear-cell ovarian cancer risks (0.80, 95% CI 0.65-0.97, p=0.03) were reduced in current smokers, and there was no significant association for serous ovarian cancers (0.99, 95% CI 0.93-1.06, p=0.8). These associations did not vary significantly by 13 sociodemographic and personal characteristics of women including their body-mass index, parity, and use of alcohol, oral contraceptives, and menopausal hormone therapy. Interpretation The excess of mucinous ovarian cancers in smokers, which is mainly of tumours of borderline malignancy, is roughly counterbalanced by the deficit of endometrioid and clear-cell ovarian cancers. The substantial variation in smoking-related risks by tumour subtype is important for understanding ovarian carcinogenesis.
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| 15. |
- Beral, V., et al.
(författare)
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Ovarian Cancer and Body Size : Individual Participant Meta-Analysis Including 25,157 Women with Ovarian Cancer from 47 Epidemiological Studies
- 2012
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Ingår i: PLoS Medicine. - : PUBLIC LIBRARY SCIENCE. - 1549-1277 .- 1549-1676. ; 9:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Only about half the studies that have collected information on the relevance of women's height and body mass index to their risk of developing ovarian cancer have published their results, and findings are inconsistent. Here, we bring together the worldwide evidence, published and unpublished, and describe these relationships. Methods and Findings: Individual data on 25,157 women with ovarian cancer and 81,311 women without ovarian cancer from 47 epidemiological studies were collected, checked, and analysed centrally. Adjusted relative risks of ovarian cancer were calculated, by height and by body mass index. Ovarian cancer risk increased significantly with height and with body mass index, except in studies using hospital controls. For other study designs, the relative risk of ovarian cancer per 5 cm increase in height was 1.07 (95% confidence interval [CI], 1.05-1.09; p<0.001); this relationship did not vary significantly by women's age, year of birth, education, age at menarche, parity, menopausal status, smoking, alcohol consumption, having had a hysterectomy, having first degree relatives with ovarian or breast cancer, use of oral contraceptives, or use of menopausal hormone therapy. For body mass index, there was significant heterogeneity (p<0.001) in the findings between ever-users and never-users of menopausal hormone therapy, but not by the 11 other factors listed above. The relative risk for ovarian cancer per 5 kg/m(2) increase in body mass index was 1.10 (95% CI, 1.07-1.13; p<0.001) in never-users and 0.95 (95% CI, 0.92-0.99; p = 0.02) in ever-users of hormone therapy. Conclusions: Ovarian cancer is associated with height and, among never-users of hormone therapy, with body mass index. In high-income countries, both height and body mass index have been increasing in birth cohorts now developing the disease. If all other relevant factors had remained constant, then these increases in height and weight would be associated with a 3% increase in ovarian cancer incidence per decade.
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| 16. |
- Callaghan, Terry, et al.
(författare)
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Multi-Decadal Changes in Tundra Environments and Ecosystems : Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)
- 2011
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40:6, s. 705-716
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Tidskriftsartikel (refereegranskat)abstract
- Understanding the responses of tundra systemsto global change has global implications. Most tundraregions lack sustained environmental monitoring and oneof the only ways to document multi-decadal change is toresample historic research sites. The International PolarYear (IPY) provided a unique opportunity for such researchthrough the Back to the Future (BTF) project (IPY project#512). This article synthesizes the results from 13 paperswithin this Ambio Special Issue. Abiotic changes includeglacial recession in the Altai Mountains, Russia; increasedsnow depth and hardness, permafrost warming, andincreased growing season length in sub-arctic Sweden;drying of ponds in Greenland; increased nutrient availabilityin Alaskan tundra ponds, and warming at mostlocations studied. Biotic changes ranged from relativelyminor plant community change at two sites in Greenland tomoderate change in the Yukon, and to dramatic increasesin shrub and tree density on Herschel Island, and in subarcticSweden. The population of geese tripled at one sitein northeast Greenland where biomass in non-grazed plotsdoubled. A model parameterized using results from a BTFstudy forecasts substantial declines in all snowbeds andincreases in shrub tundra on Niwot Ridge, Colorado overthe next century. In general, results support and provideimproved capacities for validating experimental manipulation,remote sensing, and modeling studies.
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| 17. |
- Cornelissen, Johannes H C, et al.
(författare)
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Global negative vegetation feedback to climate warming responses of leaf litter decomposition rates in cold biomes
- 2007
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 10:7, s. 619-627
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Tidskriftsartikel (refereegranskat)abstract
- Whether climate change will turn cold biomes from large long-term carbon sinks into sources is hotly debated because of the great potential for ecosystem-mediated feedbacks to global climate. Critical are the direction, magnitude and generality of climate responses of plant litter decomposition. Here, we present the first quantitative analysis of the major climate-change-related drivers of litter decomposition rates in cold northern biomes worldwide.Leaf litters collected from the predominant species in 33 global change manipulation experiments in circum-arctic-alpine ecosystems were incubated simultaneously in two contrasting arctic life zones. We demonstrate that longer-term, large-scale changes to leaf litter decomposition will be driven primarily by both direct warming effects and concomitant shifts in plant growth form composition, with a much smaller role for changes in litter quality within species. Specifically, the ongoing warming-induced expansion of shrubs with recalcitrant leaf litter across cold biomes would constitute a negative feedback to global warming. Depending on the strength of other (previously reported) positive feedbacks of shrub expansion on soil carbon turnover, this may partly counteract direct warming enhancement of litter decomposition.
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| 18. |
- Pascual, Didac, et al.
(författare)
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The missing pieces for better future predictions in subarctic ecosystems: A Torneträsk case study
- 2021
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Ingår i: Ambio. - : Springer. - 0044-7447 .- 1654-7209. ; 50:2, s. 375-392
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Forskningsöversikt (refereegranskat)abstract
- Arctic and subarctic ecosystems are experiencing substantial changes in hydrology, vegetation, permafrost conditions, and carbon cycling, in response to climatic change and other anthropogenic drivers, and these changes are likely to continue over this century. The total magnitude of these changes results from multiple interactions among these drivers. Field measurements can address the overall responses to different changing drivers, but are less capable of quantifying the interactions among them. Currently, a comprehensive assessment of the drivers of ecosystem changes, and the magnitude of their direct and indirect impacts on subarctic ecosystems, is missing. The Torneträsk area, in the Swedish subarctic, has an unrivalled history of environmental observation over 100 years, and is one of the most studied sites in the Arctic. In this study, we summarize and rank the drivers of ecosystem change in the Torneträsk area, and propose research priorities identified, by expert assessment, to improve predictions of ecosystem changes. The research priorities identified include understanding impacts on ecosystems brought on by altered frequency and intensity of winter warming events, evapotranspiration rates, rainfall, duration of snow cover and lake-ice, changed soil moisture, and droughts. This case study can help us understand the ongoing ecosystem changes occurring in the Torneträsk area, and contribute to improve predictions of future ecosystem changes at a larger scale. This understanding will provide the basis for the future mitigation and adaptation plans needed in a changing climate.
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| 19. |
- Taulavuori, E, et al.
(författare)
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Long-term exposure to enhanced ultraviolet-B radiation in the sub-arctic does not cause oxidative stress in Vaccinium myrtillus
- 1998
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Ingår i: New Phytologist. - : Wiley. - 1469-8137 .- 0028-646X. ; 140:4, s. 691-697
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this work was to assess whether or not oxidative stress had developed in a dwarf shrub bilberry (Vaccinium myrtillus L.) under long-term exposure to enhanced levels of ultraviolet-B (u.v.-B) radiation. The bilberry plants were exposed to increased u.v.-B representing a 15 stratospheric ozone depletion for seven full growing seasons (19911997) at Abisko, Swedish Lapland (68N). The oxidative stress was assessed on leaves and stems by analysing ascorbate and glutathione concentrations, and activities of the closely related enzymes ascorbate peroxidase (EC 1.11.1.11) and glutathione reductase (EC 1.6.4.2). The affects of autumnal leaf senescence and stem cold hardening on these variables were also considered. The results showed that the treatment caused scarcely any response in the studied variables, indicating that u.v.-B flux representing a 15 ozone depletion under clear sky conditions is not sufficient to cause oxidative stress in the bilberry. It is suggested that no strain was evoked since adaptation was possible under such u.v.-B increases. The studied variables did, however, respond significantly to leaf senescence and especially to stem cold hardening.
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| 20. |
- Adams, M. P., et al.
(författare)
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Water residence time controls the feedback between seagrass, sediment and light: Implications for restoration
- 2018
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Ingår i: Advances in Water Resources. - : Elsevier BV. - 0309-1708. ; 117, s. 14-26
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Tidskriftsartikel (refereegranskat)abstract
- Feedbacks between seagrass and the local environmental conditions may hinder attempts to restore seagrass by inducing alternative stable states. A one-dimensional physical-biological model was used to identify the conditions under which a feedback between seagrass, sediment and light can yield alternative stable states of seagrass presence and absence (bistability). Based on our model results, a prediction of whether a given seagrass meadow is large enough to promote seagrass growth can now be made. If the water residence time within the spatial area of the meadow is similar to or greater than the sediment settling time, which is calculated from the ratio of water depth to sediment vertical settling velocity, the meadow is large enough for the feedback to potentially reduce the local suspended sediment concentration. This has important implications for seagrass restoration: for a proposed restoration plot, if the water residence time is similar to or greater than the sediment settling time, the scale of restoration is large enough for the feedback between seagrass, sediment and light to locally improve water clarity. More generally, this calculation can be used to identify areas where this feedback is likely to generate bistability, and to estimate the minimum suitable meadow size in such locations. © 2018 Elsevier Ltd
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| 21. |
- Anisimov, O., et al.
(författare)
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Permafrost
- 2009
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Ingår i: Melting snow and ice: a call for action.. - 9788276662641 ; , s. 64-71
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 22. |
- Ariyawansa, Hiran A., et al.
(författare)
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Fungal diversity notes 111–252—taxonomic and phylogenetic contributions to fungal taxa
- 2015
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Ingår i: Fungal diversity. - : Springer Science and Business Media LLC. - 1560-2745 .- 1878-9129. ; 75, s. 27-274
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Tidskriftsartikel (refereegranskat)abstract
- This paper is a compilation of notes on 142 fungal taxa, including five new families, 20 new genera, and 100 new species, representing a wide taxonomic and geographic range. The new families, Ascocylindricaceae, Caryosporaceae and Wicklowiaceae (Ascomycota) are introduced based on their distinct lineages and unique morphology. The new Dothideomycete genera Pseudomassariosphaeria (Amniculicolaceae), Heracleicola, Neodidymella and P s e u d o m i c ros p h a e r i o p s i s ( D id y m e l l a c e a e ) , P s e u d o p i t h o m y c e s ( D i d y m o s p h a e r i a c e a e ) , Brunneoclavispora, Neolophiostoma and Sulcosporium (Halotthiaceae), Lophiohelichrysum (Lophiostomataceae), G a l l i i c o l a , Popul o c re s c e n t i a a nd Va g i c o l a (Phaeosphaeriaceae), Ascocylindrica (Ascocylindricaceae), E l o n g a t o p e d i c e l l a t a ( R o u s s o e l l a c e a e ) , Pseudoasteromassaria (Latoruaceae) and Pseudomonodictys (Macrodiplodiopsidaceae) are introduced. The newly described species of Dothideomycetes (Ascomycota) are Pseudomassariosphaeria bromicola (Amniculicolaceae), Flammeascoma lignicola (Anteagloniaceae), Ascocylindrica marina (Ascocylindricaceae) , Lembosia xyliae (Asterinaceae), Diplodia crataegicola and Diplodia galiicola ( B o t r yosphae r i a cea e ) , Caryospor a aquat i c a (Caryosporaceae), Heracleicola premilcurensis and Neodi dymell a thai landi cum (Didymellaceae) , Pseudopithomyces palmicola (Didymosphaeriaceae), Floricola viticola (Floricolaceae), Brunneoclavispora bambusae, Neolophiostoma pigmentatum and Sulcosporium thailandica (Halotthiaceae), Pseudoasteromassaria fagi (Latoruaceae), Keissleriella dactylidicola (Lentitheciaceae), Lophiohelichrysum helichrysi (Lophiostomataceae), Aquasubmersa japonica (Lophiotremataceae) , Pseudomonodictys tectonae (Macrodiplodiopsidaceae), Microthyrium buxicola and Tumidispora shoreae (Microthyriaceae), Alloleptosphaeria clematidis, Allophaeosphaer i a c y t i s i , Allophaeosphae r i a subcylindrospora, Dematiopleospora luzulae, Entodesmium artemisiae, Galiicola pseudophaeosphaeria, Loratospora(Basidiomycota) are introduced together with a new genus Neoantrodiella (Neoantrodiellaceae), here based on both morphology coupled with molecular data. In the class Agaricomycetes, Agaricus pseudolangei, Agaricus haematinus, Agaricus atrodiscus and Agaricus exilissimus (Agaricaceae) , Amanita m e l l e i a l b a , Amanita pseudosychnopyramis and Amanita subparvipantherina (Amanitaceae), Entoloma calabrum, Cora barbulata, Dictyonema gomezianum and Inocybe granulosa (Inocybaceae), Xerocomellus sarnarii (Boletaceae), Cantharellus eucalyptorum, Cantharellus nigrescens, Cantharellus tricolor and Cantharellus variabilicolor (Cantharellaceae), Cortinarius alboamarescens, Cortinarius brunneoalbus, Cortinarius ochroamarus, Cortinarius putorius and Cortinarius seidlii (Cortinariaceae), Hymenochaete micropora and Hymenochaete subporioides (Hymenochaetaceae), Xylodon ramicida (Schizoporaceae), Colospora andalasii (Polyporaceae), Russula guangxiensis and Russula hakkae (Russulaceae), Tremella dirinariae, Tremella graphidis and Tremella pyrenulae (Tremellaceae) are introduced. Four new combinations Neoantrodiella gypsea, Neoantrodiella thujae (Neoantrodiellaceae), Punctulariopsis cremeoalbida, Punctulariopsis efibulata (Punctulariaceae) are also introduced here for the division Basidiomycota. Furthermore Absidia caatinguensis, Absidia koreana and Gongronella koreana (Cunninghamellaceae), Mortierella pisiformis and Mortierella formosana (Mortierellaceae) are newly introduced in the Zygomycota, while Neocallimastix cameroonii and Piromyces irregularis (Neocallimastigaceae) ar e i n t roduced i n the Neocallimastigomycota. Reference specimens or changes in classification and notes are provided for Alternaria ethzedia, Cucurbitaria ephedricola, Austropleospora, Austropleospora archidendri, Byssosphaeria rhodomphala, Lophiostoma caulium, Pseudopithomyces maydicus, Massariosphaeria, Neomassariosphaeria and Pestalotiopsis montellica.
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| 23. |
- Armstrong, R., et al.
(författare)
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Snow
- 2009
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Ingår i: Melting snow and ice – a call for action. - 9788276662641 ; , s. 24-31
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 24. |
- Callaghan, Terry V., et al.
(författare)
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Changing snow cover and its impacts
- 2011
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Ingår i: Snow, Water, Ice and Permafrost in the Arctic (SWIPA). - Oslo : Arctic Monitoring and Assessment Programme. - 9788279710714 ; , s. 4:1-4:58
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Bokkapitel (refereegranskat)
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| 25. |
- Callaghan, Terry V., et al.
(författare)
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Ecosystem change and stability over multiple decades in the Swedish subarctic : complex processes and multiple drivers
- 2013
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Ingår i: Philosophical Transactions of the Royal Society of London. Biological Sciences. - : The Royal Society. - 0962-8436 .- 1471-2970. ; 368:1624
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Tidskriftsartikel (refereegranskat)abstract
- The subarctic environment of northernmost Sweden has changed over the past century, particularly elements of climate and cryosphere. This paper presents a unique geo-referenced record of environmental and ecosystem observations from the area since 1913. Abiotic changes have been substantial. Vegetation changes include not only increases in growth and range extension but also counterintuitive decreases, and stability: all three possible responses. Changes in species composition within the major plant communities have ranged between almost no changes to almost a 50 per cent increase in the number of species. Changes in plant species abundance also vary with particularly large increases in trees and shrubs (up to 600%). There has been an increase in abundance of aspen and large changes in other plant communities responding to wetland area increases resulting from permafrost thaw. Populations of herbivores have responded to varying management practices and climate regimes, particularly changing snow conditions. While it is difficult to generalize and scale-up the site-specific changes in ecosystems, this very site-specificity, combined with projections of change, is of immediate relevance to local stakeholders who need to adapt to new opportunities and to respond to challenges. Furthermore, the relatively small area and its unique datasets are a microcosm of the complexity of Arctic landscapes in transition that remains to be documented.
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| 26. |
- Callaghan, Terry V., et al.
(författare)
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Multiple Effects of Changes in Arctic Snow Cover
- 2011
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Ingår i: Ambio: a Journal of Human Environment. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 40, s. 32-45
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Tidskriftsartikel (refereegranskat)abstract
- Snow cover plays a major role in the climate, hydrological and ecological systems of the Arctic and other regions through its influence on the surface energy balance (e.g. reflectivity), water balance (e.g. water storage and release), thermal regimes (e.g. insulation), vegetation and trace gas fluxes. Feedbacks to the climate system have global consequences. The livelihoods and well-being of Arctic residents and many services for the wider population depend on snow conditions so changes have important consequences. Already, changing snow conditions, particularly reduced summer soil moisture, winter thaw events and rain-on-snow conditions have negatively affected commercial forestry, reindeer herding, some wild animal populations and vegetation. Reductions in snow cover are also adversely impacting indigenous peoples' access to traditional foods with negative impacts on human health and well-being. However, there are likely to be some benefits from a changing Arctic snow regime such as more even run-off from melting snow that favours hydropower operations.
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| 27. |
- Cornelissen, C, et al.
(författare)
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Global change and arctic ecosystems : is lichen decline a function of increases in vascular plant biomass?
- 2001
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Ingår i: Journal of Ecology. - : Wiley. - 0022-0477 .- 1365-2745. ; 89:6, s. 984-994
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Tidskriftsartikel (refereegranskat)abstract
- 1 Macrolichens are important for the functioning and biodiversity of cold northern ecosystems and their reindeer-based cultures and economics. 2 We hypothesized that, in climatically milder parts of the Arctic, where ecosystems have relatively dense plant canopies, climate warming and/or increased nutrient availability leads to decline in macrolichen abundance as a function of increased abundance of vascular plants. In more open high-arctic or arctic-alpine plant communities such a relationship should be absent. To test this, we synthesized cross-continental arctic vegetation data from ecosystem manipulation experiments simulating mostly warming and increased nutrient availability, and compared these with similar data from natural environmental gradients. 3 Regressions between abundance or biomass of macrolichens and vascular plants were consistently negative across the subarctic and mid-arctic experimental studies. Such a pattern did not emerge in the coldest high-arctic or arctic-alpine sites. The slopes of the negative regressions increased across 10 sites as the climate became milder (as indicated by a simple climatic index) or the vegetation denser (greater site above-ground biomass). 4 Seven natural vegetation gradients in the lower-altitude sub- and mid-arctic zone confirmed the patterns seen in the experimental studies, showing consistent negative relationships between abundance of macrolichens and vascular plants. 5 We conclude that the data supported the hypothesis. Macrolichens in climatically milder arctic ecosystems may decline if and where global changes cause vascular plants to increase in abundance. 6 However, a refining of our findings is needed, for instance by integrating other abiotic and biotic effects such as reindeer grazing feedback on the balance between vascular plants and lichens.
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| 28. |
- Cornwell, William K., et al.
(författare)
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Plant species traits are the predominant control on litter decomposition rates within biomes worldwide
- 2008
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Ingår i: Ecology Letters. - : Wiley. - 1461-023X .- 1461-0248. ; 11:10, s. 1065-1071
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Tidskriftsartikel (refereegranskat)abstract
- Worldwide decomposition rates depend both on climate and the legacy of plant functional traits as litter quality. To quantify the degree to which functional differentiation among species affects their litter decomposition rates, we brought together leaf trait and litter mass loss data for 818 species from 66 decomposition experiments on six continents. We show that: (i) the magnitude of species-driven differences is much larger than previously thought and greater than climate-driven variation; (ii) the decomposability of a species' litter is consistently correlated with that species' ecological strategy within different ecosystems globally, representing a new connection between whole plant carbon strategy and biogeochemical cycling. This connection between plant strategies and decomposability is crucial for both understanding vegetation-soil feedbacks, and for improving forecasts of the global carbon cycle.
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| 29. |
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| 30. |
- Jägerbrand, Annika K, 1972-, et al.
(författare)
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Effects of Climate Change on tundra bryophytes
- 2011
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Ingår i: Bryophyte Ecology and Climate Change. - Cambridge, UK : Cambridge University Press. - 9780521757775 ; , s. 211-236
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 31. |
- Kokfelt, Ulla, et al.
(författare)
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Ecosystem responses to increased precipitation and permafrost decay in subarctic Sweden inferred from peat and lake sediments
- 2009
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 15:7, s. 1652-1663
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Tidskriftsartikel (refereegranskat)abstract
- Recent accelerated decay of discontinuous permafrost at the Stordalen Mire in northern Sweden has been attributed to increased temperature and snow depth, and has caused expansion of wet minerotrophic areas leading to significant changes in carbon cycling in the mire. In order to track these changes through time and evaluate potential forcing mechanisms, this paper analyses a peat succession and a lake sediment sequence from within the mire, providing a record for the last 100 years, and compares these with monitored climate and active layer thickness data. The peat core was analysed for testate amoebae to reconstruct changes in peatland surface moisture conditions and water table fluctuations. The lake sediment core was analysed by near infrared spectroscopy to infer changes in the total organic carbon (TOC) concentration of the lake-water, and changes in δ13C and C, N and δ15N to track changes in the dissolved inorganic carbon (DIC) pool and the influence of diagenetic effects on sediment organic matter, respectively. Results showed that major shifts towards increased peat surface moisture and TOC concentration of the lake-water occurred around 1980, one to two decades earlier than a temperature driven increase in active layer thickness. Comparison with monitored temperature and precipitation from a nearby climate station indicates that this change in peat surface moisture is related to June–September (JJAS) precipitation and that the increase in lake-water TOC concentration reflects an increase in total annual precipitation. A significant depletion in 13C of sediment organic matter in the early 1980s probably reflects the effect of a single or a few consecutive years with anomalously high summer precipitation, resulting in elevated DIC content of the lake water, predominantly originating from increased export and subsequent respiration of organic carbon from the mire. Based on these results, it was not possible to link proxy data obtained on peat and lake-sediment records directly to permafrost decay. Instead our data indicate that increased precipitation and anomalously high rainfall during summers had a significant impact on the mire and the adjacent lake ecosystem. We therefore propose that effects of increased precipitation should be considered when evaluating potential forcing mechanisms of recent changes in carbon cycling in the subarctic.
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| 32. |
- Lett, Signe, et al.
(författare)
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Can bryophyte groups increase functional resolution in tundra ecosystems?
- 2022
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Ingår i: Arctic Science. - Ottawa : Canadian Science Publishing. - 2368-7460. ; 8:3, s. 609-637
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Tidskriftsartikel (refereegranskat)abstract
- The relative contribution of bryophytes to plant diversity, primary productivity, and ecosystem functioning increases towards colder climates. Bryophytes respond to environmental changes at the species level, but because bryophyte species are relatively difficult to identify, they are often lumped into one functional group. Consequently, bryophyte function remains poorly resolved. Here, we explore how higher resolution of bryophyte functional diversity can be encouraged and implemented in tundra ecological studies. We briefly review previous bryophyte functional classifications and the roles of bryophytes in tundra ecosystems and their susceptibility to environmental change. Based on shoot morphology and colony organization, we then propose twelve easily distinguishable bryophyte functional groups. To illustrate how bryophyte functional groups can help elucidate variation in bryophyte effects and responses, we compiled existing data on water holding capacity, a key bryophyte trait. Although plant functional groups can mask potentially high interspecific and intraspecific variability, we found better separation of bryophyte functional group means compared with previous grouping systems regarding water holding capacity. This suggests that our bryophyte functional groups truly represent variation in the functional roles of bryophytes in tundra ecosystems. Lastly, we provide recommendations to improve the monitoring of bryophyte community changes in tundra study sites.
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| 33. |
- Nonyane, Bareng As, et al.
(författare)
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Equity improvements in maternal and newborn care indicators : results from the Bardiya district of Nepal
- 2016
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Ingår i: Health Policy and Planning. - : Oxford University Press (OUP). - 0268-1080 .- 1460-2237. ; 31:4, s. 405-414
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Tidskriftsartikel (refereegranskat)abstract
- Community-based maternal and newborn care interventions have been shown to improve neonatal survival and other key health indicators. It is important to evaluate whether the improvement in health indicators is accompanied by a parallel increase in the equitable distribution of the intervention activities, and the uptake of healthy newborn care practices. We present an analysis of equity improvements after the implementation of a Community Based Newborn Care Package (CB-NCP) in the Bardiya district of Nepal. The package was implemented alongside other programs that were already in place within the district. We present changes in concentration indices (CIndices) as measures of changes in equity, as well as percentage changes in coverage, between baseline and endline. The CIndices were derived from wealth scores that were based on household assets, and they were compared using t-tests. We observed statistically significant improvements in equity for facility delivery [CIndex: -0.15 (-0.24, -0.06)], knowledge of at least three newborn danger signs [-0.026(-0.06, -0.003)], breastfeeding within 1 h [-0.05(-0.11, -0.0001)], at least one antenatal visit with a skilled provider [-0.25(-0.04, -0.01)], at least four antenatal visits from any provider [-0.15(-0.19, -0.10)] and birth preparedness [-0.09(-0.12, -0.06)]. The largest increases in practices were observed for facility delivery (50%), immediate drying (34%) and delayed bathing (29%). These results and those of similar studies are evidence that community-based interventions delivered by female community health volunteers can be instrumental in improving equity in levels of facility delivery and other newborn care behaviours. We recommend that equity be evaluated in other similar settings within Nepal in order to determine if similar results are observed.
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| 34. |
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| 35. |
- Reist, James D., et al.
(författare)
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SWIPA Synthesis: Implications of Findings
- 2011
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Ingår i: Snow, Water, Ice and Permafrost in the Arctic (swipa): Climate Change and the Cryosphere. - 9788279710714 ; , s. 1-15
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Bokkapitel (refereegranskat)
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| 36. |
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| 37. |
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| 38. |
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| 39. |
- Walker, M. D., et al.
(författare)
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Plant community responses to experimental warming across the tundra biome
- 2006
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 103:5, s. 1342-1346
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Tidskriftsartikel (refereegranskat)abstract
- Recent observations of changes in some tundra ecosystems appear to be responses to a warming climate. Several experimental studies have shown that tundra plants and ecosystems can respond strongly to environmental change, including warming; however, most studies were limited to a single location and were of short duration and based on a variety of experimental designs. In addition, comparisons among studies are difficult because a variety of techniques have been used to achieve experimental warming and different measurements have been used to assess responses. We used metaanalysis on plant community measurements from standardized warming experiments at 11 locations across the tundra biome involved in the International Tundra Experiment. The passive warming treatment increased plant-level air temperature by 1-3 degrees C, which is in the range of predicted and observed warming for tundra regions. Responses were rapid and detected in whole plant communities after only two growing seasons. Overall, warming increased height and cover of deciduous shrubs and graminoids, decreased cover of mosses and lichens, and decreased species diversity and evenness. These results predict that warming will cause a decline in biodiversity across a wide variety of tundra, at least in the short term. They also provide rigorous experimental evidence that recently observed increases in shrub cover in many tundra regions are in response to climate warming. These changes have important implications for processes and interactions within tundra ecosystems and between tundra and the atmosphere.
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| 40. |
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