| 1. |
- Niemi, MEK, et al.
(författare)
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- 2021
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swepub:Mat__t
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| 2. |
- Kanai, M, et al.
(författare)
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- 2023
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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. |
- 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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| 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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| 11. |
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| 12. |
- 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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| 13. |
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| 14. |
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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. |
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| 21. |
- 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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| 22. |
- Callaghan, T. V., et al.
(författare)
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Arctic Cryosphere: Changes and Impacts
- 2011
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Ingår i: Ambio: a Journal of Human Environment. - : Springer Science and Business Media LLC. - 0044-7447. ; 40, s. 3-5
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Tidskriftsartikel (refereegranskat)abstract
- The Arctic cryosphere is a critically important component of the earth system, affecting the earth's energy balance, sea level, greenhouse gases and atmospheric circulation, transport of heat through ocean circulation, ecology and human resource use and well-being. The Arctic cryosphere is, however, changing rapidly with multiple important consequences that will potentially affect the earth system including the human population. The drivers of changes in the Arctic's cryosphere, the recent and projected changes in the cryosphere and the consequences for future climate warming, sea level rise, ecology and human well-being, have been comprehensively assessed by the Arctic Council's Snow Water, Ice, and Permafrost in the Arctic (SWIPA) Project through its Arctic Monitoring and Assessment Programme Working Group. This article introduces the assessment and the associated papers within a special issue of the journal Ambio that extract and present some of the major findings of the SWIPA report.
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| 23. |
- Callaghan, T. V., et al.
(författare)
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Effects on the function of arctic ecosystems in the short- and long-term perspectives
- 2004
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Ingår i: Ambio: a Journal of Human Environment. - : Royal Swedish Academy of Sciences. - 0044-7447. ; 33, s. 448-458
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Tidskriftsartikel (refereegranskat)abstract
- Abstract in UndeterminedHistorically, the function of Arctic ecosystems in terms of cycles of nutrients and carbon has led to low levels of primary production and exchanges of energy, water and greenhouse gases have led to low local and regional cooling. Sequestration of carbon from atmospheric CO2, in extensive, cold organic soils and the high albedo from low, snow-covered vegetation have had impacts on regional climate. However, many aspects of the functioning of Arctic ecosystems are sensitive to changes in climate and its impacts on biodiversity. The current Arctic climate results in slow rates of organic matter decomposition. Arctic ecosystems therefore tend to accumulate organic matter and elements despite low inputs. As a result, soil-available elements like nitrogen and phosphorus are key limitations to increases in carbon fixation and further biomass and organic matter accumulation. Climate warming is expected to increase carbon and element turnover, particularly in soils, which may lead to initial losses of elements but eventual, slow recovery. Individual species and species diversity have clear impacts on element inputs and retention in Arctic ecosystems. Effects of increased CO2 and UV-B on whole ecosystems, on the other hand, are likely to be small although effects on plant tissue chemisty, decomposition and nitrogen fixation may become important in the long-term. Cycling of carbon in trace gas form is mainly as CO2 and CH4. Most carbon loss is in the form of CO2, produced by both plants and soil biota. Carbon emissions as methane from wet and moist tundra ecosystems are about 5% of emissions as CO2 and are responsive to warming in the absence of any other changes. Winter processes and vegetation type also affect CH4 emissions as well as exchanges of energy between biosphere and atmosphere. Arctic ecosystems exhibit the largest seasonal changes in energy exchange of any terrestrial ecosystem because of the large changes in albedo from late winter, when snow reflects most incoming radiation, to summer when the ecosystem absorbs most incoming radiation. Vegetation profoundly influences the water and energy exchange of Arctic ecosystems. Albedo during the period of snow cover declines from tundra to forest tundra to deciduous forest to evergreen forest. Shrubs and trees increase snow depth which in turn increases winter soil temperatures. Future changes in vegetation driven by climate change are therefore, very likely to profoundly alter regional climate.
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| 24. |
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| 25. |
- Kalimo, H., et al.
(författare)
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Details of neuropathology in Arctic Alzheimer's disease
- 2010
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Ingår i: Abstracts of the XVIIth International Congress of Neuropathology (ICN 2010), Salzburg, Austria, 11-15 September 2010. - : Wiley. ; , s. 22-23
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 26. |
- Olofsson, J, et al.
(författare)
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Herbivores inhibit climate-driven shrub expansion on the tundra
- 2009
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 15, s. 2681-2693
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Tidskriftsartikel (refereegranskat)abstract
- Recent Pan-Arctic shrub expansion has been interpreted as a response to a warmer climate. However, herbivores can also influence the abundance of shrubs in arctic ecosystems. We addressed these alternative explanations by following the changes in plant community composition during the last 10 years in permanent plots inside and outside exclosures with different mesh sizes that exclude either only reindeer or all mammalian herbivores including voles and lemmings. The exclosures were replicated at three forest and tundra sites at four different locations along a climatic gradient (oceanic to continental) in northern Fennoscandia. Since the last 10 years have been exceptionally warm, we could study how warming has influenced the vegetation in different grazing treatments. Our results show that the abundance of the dominant shrub, Betula nana, has increased during the last decade, but that the increase was more pronounced when herbivores were excluded. Reindeer have the largest effect on shrubs in tundra, while voles and lemmings have a larger effect in the forest. The positive relationship between annual mean temperature and shrub growth in the absence of herbivores and the lack of relationships in grazed controls is another indication that shrub abundance is controlled by an interaction between herbivores and climate. In addition to their effects on taller shrubs (40.3 m), reindeer reduced the abundance of lichens, whereas microtine rodents reduced the abundance of dwarf shrubs (o0.3 m) and mosses. In contrast to short-term responses, competitive interactions between dwarf shrubs and lichens were evident in the long term. These results show that herbivores have to be considered in order to understand how a changing climate will influence tundra ecosystems.
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| 27. |
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| 28. |
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| 29. |
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| 30. |
- Aerts, R., et al.
(författare)
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Seasonal climate manipulations have only minor effects on litter decomposition rates and N dynamics but strong effects on litter P dynamics of sub-arctic bog species
- 2012
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Ingår i: Oecologia. - : Springer. - 0029-8549 .- 1432-1939. ; 170:3, s. 809-819
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Tidskriftsartikel (refereegranskat)abstract
- Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis < Betula < Rubus. After 4 years, overall mass loss in the climate-treatment plots was 10 % higher compared to the ambient incubation environment. Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.
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| 31. |
- 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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| 32. |
- 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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| 33. |
- Björn, Lars Olof, et al.
(författare)
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Effects of ozone depletion and increased ultraviolet-B radiation on northern vegetation
- 1999
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Ingår i: Polar Research. - : Norwegian Polar Institute. - 0800-0395 .- 1751-8369. ; 18:2, s. 331-337
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Tidskriftsartikel (refereegranskat)abstract
- The stratospheric ozone layer has been depleted at high and mid-latitudes as a consequence of man's pollution of the atmosphere, and this results in increasing ultraviolet-B radiation at ground level. We investigate the effects of further radiation increases on plants and ecosystems by irradiating natural sub-Arctic and Arctic vegetation with artificial W-B radiation in field experiments extending over several years. Our experimental sites are located at Abisko, in northern Sweden (68 degrees N), and Adventdalen, on the island of Spitsbergen (78 degrees N). Additional UV-B induced interspecific differences in plant response in terms of reduced (or, in one case, increased) growth, changed morphology and changed pigment content. In some cases effects seem to be accumulated from one year to another. Plant litter decomposition is retarded. We are also studying how UV-B enhancement may affect the interaction between species. In some experiments we combine UV-B enhancement with changes in other factors: carbon dioxide concentration, water availability, and temperature. In some cases the effect of radiation enhancement is modified, or even reversed, by such changes. Over a four year period we did not find any significant radiation induced change in species composition, but based on the effects on individual plant species, such changes can be expected to take place over a longer time.
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| 34. |
- Björn, Lars Olof, et al.
(författare)
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The problem of ozone depletion in northern Europe
- 1998
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Ingår i: Ambio: a Journal of Human Environment. - 0044-7447. ; 27:4, s. 275-279
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Tidskriftsartikel (refereegranskat)abstract
- Ozone in the atmosphere, mainly in the stratosphere, absorbs most of the ultraviolet-B (wavelength 280-315 nm) radiation from the sun, which can destroy DNA and other biologically important molecules and, thereby, damage living organisms. Due to the pollution of the atmosphere by humans, the ozone layer is presently being depleted, more rapidly at higher latitudes than at lower, and more rapidly over Scandinavia than over most geographical regions at corresponding latitudes. Ultraviolet-B radiation is generally more intense in mountain regions than at sea level. We have experiments in progress in which we simulate the effects of further ozone depletion on terrestrial ecosystems (mountain heaths, bogs, tundra) by irradiating them with artificial ultraviolet-B radiation. Effects on the growth of dwarf-shrubs and mosses and on plant litter decomposition are described.
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| 35. |
- Bowen, Tracey, et al.
(författare)
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Disparities in work-integrated learning experiences for students who present as women : an international study of biases, barriers, and challenges
- 2024
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Ingår i: Higher Education, Skills and Work-based Learning. - : Emerald Group Publishing Limited. - 2042-3896 .- 2042-390X. ; 14:2, s. 313-328
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Tidskriftsartikel (refereegranskat)abstract
- Purpose: This study identifies gendered disparities among women students participating in work-integrated learning and explores the effects of the disparities on their perceptions on perceived opportunities, competencies, sense of belonging, and professional identity. Design/methodology/approach: A series of semi-structured focus groups were run with 59 participants at six higher education institutions in four countries (Australia, Canada, Sweden, United Kingdom). All focus groups were designed with the same questions and formatting. Findings: Thematic analysis of the transcripts revealed two overarching themes, namely perceptions of self and interactions with others in work placements. Theme categories included awareness of self-presentation, sense of autonomy, perceived Allies, emotional labour, barriers to opportunity, sense of belonging, intersections of identity, and validation value. Originality/value: This study fills an important gap in the international literature about gendered experiences in WIL and highlights inequalities that women experience while on work placements.
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| 36. |
- Callaghan, C. T., et al.
(författare)
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Validation of a globally-applicable method to measure urban tolerance of birds using citizen science data
- 2021
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Ingår i: Ecological Indicators. - : Elsevier BV. - 1470-160X. ; 120
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Tidskriftsartikel (refereegranskat)abstract
- Understanding species-specific responses to urbanization is essential to mitigate and preserve biodiversity in the face of increasing urbanization, but a major challenge is how to estimate urban tolerances for a wide array of species applicable over disparate regions. A promising approach is to assess urban tolerance by integrating georeferenced information on species detections from citizen science data with estimations of urbanization intensity based on remotely-sensed night-time lights. While such citizen science urbanness scores (CSUS) are cost-effective, intuitive, and easily-repeatable anywhere in the world, whether the scores accurately describe urban tolerance still awaits empirical verification. By analysing > 900 bird species worldwide, we find that CSUS cor relates well with a standard measure of urban tolerance based on changes in abundance between urbanized and non-urbanized nearby habitats. Our analyses show that there is substantial variability in the relationship between these two metrics, but nevertheless highlights the potential for the CSUS approach in the future. Future improvements to the index, including incorporating rare species, and understanding the influence of intraspecific variability in response to urbanization, will be necessary to maximize the broad utility of the approach.
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| 37. |
- Callaghan, D. A., et al.
(författare)
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Geographic range and population size of the habitat specialist Codonoblepharon forsteri in a changing climate
- 2022
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Ingår i: Journal of Bryology. - 0373-6687 .- 1743-2820. ; 44:1, s. 35-40
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Codonoblepharon forsteri is a rare epiphytic moss characteristically associated with water-filled holes in trees. This study aims to review its range and population and assess effects of climate change.Methods: An inventory of sites from where C. forsteri has been recorded was compiled. Extent of Occurrence (EOO) and Area of Occupancy (AOO) were calculated. Population size was estimated, using an occupied tree as an ‘individual-equivalent’ of the moss. Climatic conditions of its current distribution were characterised, and an ensemble model of its distribution generated. The latter was projected onto present and future climatic layers.Results: C. forsteri has been recorded from 205 sites in 18 countries, in Europe, N Africa and SW Asia. It has been undergoing an overall decline. Most sites have few occupied trees, and a world population of 1000–10,000 individual-equivalents is estimated. Model projections suggest the species will experience a range increase of +0.27–0.78 by 2050 and +0.34–0.97 by 2070, especially in the NW, in particular across France and the UK. Range loss is predicted to be -0.16–0.23 in 2050 and -0.18–0.32 in 2070, affecting the driest areas of the current range around the Mediterranean, especially in N Africa.Conclusions: C. forsteri has a relatively large EOO but a relatively small AOO, likely the product of its habitat specialism. A major reason for recent declines appears to be widespread abandonment of traditional ‘pollarding’ of trees. The potential climatic range of the species will shift significantly northwards over the next few decades
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| 38. |
- Callaghan, P. T., et al.
(författare)
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Diffusion-diffusion correlation and exchange as a signature for local order and dynamics
- 2004
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Ingår i: Journal of Chemical Physics. - : AIP Publishing. - 0021-9606 .- 1089-7690. ; 120:8, s. 4032-4038
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Tidskriftsartikel (refereegranskat)abstract
- We demonstrate the use of new two-dimensional nuclear magnetic resonance experiments in the examination of local diffusional anisotropy under conditions of global isotropy. The methods, known as diffusion-diffusion correlation spectroscopy and diffusion exchange spectroscopy, employ successive pairs of magnetic field gradient pulses, with signal analysis using two-dimensional inverse Laplace transformation. Diffusional anisotropy is measured for water molecules in a polydomain lamellar phase lyotropic liquid crystal, 40 wt % nonionic surfactant C10E3 (C10H21O(CH2CH2O)(6)H) in H2O.
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| 39. |
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| 40. |
- Callaghan, TV, et al.
(författare)
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Key findings and extended summaries
- 2004
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Ingår i: Ambio: a Journal of Human Environment. - 0044-7447. ; 33:7, s. 386-392
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Tidskriftsartikel (refereegranskat)
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| 41. |
- Callaghan, T.V., et al.
(författare)
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Arctic Terrestrial Ecosystems
- 2013
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Ingår i: Encyclopedia of Biodiversity, second edition. ; , s. 227-244
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Bokkapitel (refereegranskat)
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| 42. |
- Callaghan, T.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): Climate Change and the Cryosphere. - 9788279710714 ; , s. 1-59
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Bokkapitel (refereegranskat)abstract
- This report presents the findings of of the "Snow, Water, Ice and Permafrost in the Arctic (SWIPA) : Climate Change and the Cryosphere" assessment, the third AMAP assessment on arctic climate issues and a follow-up on the Arctic Climate Impact Assessment (ACIA) published in 2005. The assessment was conducted between 2008 and 2011 by over 200 scientists, experts, and members of Native groups, and brings together the latest knowledge about the changing state of each component of the arctic 'cryosphere' (the part of the Earth's surface that is seasonally or perennially frozen).
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| 43. |
- Chapin III, F.S., et al.
(författare)
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Polar Systems
- 2006
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Ingår i: Millenium Ecosystem Assessment 2005 - Current State and Trends. - 1559632283 - 9781559632287 ; 1
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 44. |
- 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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| 45. |
- 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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| 46. |
- Johanson, U, et al.
(författare)
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The effects of an enhanced UV-B radiation on a sub-arctic heath ecosystem
- 1995
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Ingår i: Ambio: a Journal of Human Environment. - 0044-7447. ; 24:2, s. 106-112
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Tidskriftsartikel (refereegranskat)abstract
- To investigate the effects of increased UV-B radiation on a natural subarctic ecosystem a field irradiation experiment was established at Abisko, northern Sweden. The vegetation in the plots consists of a dwarf shrub layer with mosses and lichens beneath. Many response variables of the vegetation and soil are measured in these plots, e.g. photosynthesis, growth, phenology, changes in species composition and decomposition. This paper describes the methods used and some initial results. Decomposition was imparied by enhanced UV-B radiation. UV-B directly affected decomposition processes and also affected them indirectly by altering the tissue chemistry of leaves. The annual growth of the dwarf shrubs was lower under enhanced UV-B. This was more pronounced in evergreen than in deciduous species. Leaf thickness of the dwarf shrubs was changed by UV-B. The leaves of the evergreen Vaccinium vitis-idaea grew thicker, while those of the two deciduous species V. myrtillus and V. uliginosum grew thinner. In the moss Hylocomium splendens, the phenological development was accelerated under enhanced UV-B radiation. Its growth (number of primary branches, length and dry weight) also increased.
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| 47. |
- Johanson, U, et al.
(författare)
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The Effects of Enhanced UV-B Radiation on the Growth of Dwarf Shrubs in a Subarctic Heathland
- 1995
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Ingår i: Functional Ecology. - 1365-2435. ; 9:5, s. 713-719
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Tidskriftsartikel (refereegranskat)abstract
- In a field irradiation experiment UV-B radiation was enhanced to simulate 15% ozone depletion under clear sky conditions in northern Sweden. This was accomplished by using UV-B fluorescent lamps mounted on metal frames raised over a naturally growing plant community. 2. The study area consisted of a dwarf shrub heath mainly composed of the four species Vaccinium vitis-idaea, V. myrtillus, V. uliginosum and Empetrum hermaphroditum. The absolute annual stem growth, relative stem growth and absolute leaf growth were recorded for different years. 3. The relative growth was significantly reduced by UV-B enhancement in the two evergreen species V. vitis-idaea (27% after 2 years of enhanced UV-B) and E. hermaphroditum (14% after 1 year and 33% after 2 years). The two deciduous species also showed a tendency for decreased relative growth under enhanced UV-B, but this effect was not statistically significant. 4. The leaf thickness of V. vitis-idaea increased both during 1992 (9%) and 1993 (4%). In contrast, the two deciduous species V. myrtillus and V. uliginosum developed thinner leaves under enhanced UV-B both during 1992 (4% for V. myrtillus, 6% for V. uliginosum) and 1993 (9% for V. myrtillus, 10% for V. uliginosum).
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| 48. |
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| 49. |
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