| 11. |
- Hansson, Karna, et al.
(författare)
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Carbon and nitrogen pools and fluxes above and below ground in spruce, pine and birch stands in southern Sweden
- 2013
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 309, s. 28-35
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Tidskriftsartikel (refereegranskat)abstract
- We synthesised results on soil carbon (C) and nitrogen (N) fluxes and the accumulation of soil organic C and N under adjacent 50-year-old Norway spruce, Scots pine and silver birch stands growing on similar soils and evaluated the different processes involved. C and N budgets were calculated. Spruce stands had larger stocks of C and N in biomass and soil than birch stands, with pine intermediate. The differences in soil stocks were mainly found in the organic layer, whereas differences in the mineral soil were small. The study showed that there is no simple answer to what is causing the differences in soil C and N stocks, because several processes are interacting. Spruce and pine trees had higher biomass and litter production than birch trees, but total litter inputs showed no significant difference between stands, because the rich ground vegetation under pine and birch contributed with substantial litter inputs, in contrast to the poor ground vegetation under spruce. Decomposition rate (per g of C) was markedly higher under birch than under spruce and pine resulting in lower C and N stocks in the organic layer. This effect was amplified by higher abundance and biomass of earthworms, favoured by higher pH and palatable litter under birch. Earthworm bioturbation probably both increased decomposition rate and damaged the ectomycorrhizal network with negative consequences for the formation of mycorrhizal litter and C storage. In conclusion, the direct effects of spruce, pine and birch litter on C and N pools and fluxes were modified by indirect effects of understorey structure, pH and earthworm responses. (C) 2013 Elsevier B.V. All rights reserved.
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| 12. |
- Hansson, Karna, et al.
(författare)
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Differences in soil properties in adjacent stands of Scots pine, Norway spruce and silver birch in SW Sweden
- 2011
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Ingår i: Forest Ecology and Management. - : Elsevier BV. - 0378-1127 .- 1872-7042. ; 262, s. 522-530
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Tidskriftsartikel (refereegranskat)abstract
- Soil properties were compared in adjacent 50-year-old Norway spruce, Scots pine and silver birch stands 26 growing on similar soils in south-west Sweden. The effects of tree species were most apparent in the 27 humus layer and decreased with soil depth. At 20–30 cm depth in the mineral soil, species differences 28 in soil properties were small and mostly not significant. Soil C, N, K, Ca, Mg, and Na content, pH, base sat- 29 uration and fine root biomass all significantly differed between humus layers of different species. Since 30 the climate, parent material, land use history and soil type were similar, the differences can be ascribed to 31 tree species. Spruce stands had the largest amounts of carbon stored down to 30 cm depth in mineral soil 32 (7.3 kg C m??2), whereas birch stands, with the lowest production, smallest amount of litterfall and lowest 33 C:N ratio in litter and humus, had the smallest carbon pool (4.1 kg C m??2), with pine intermediate 34 (4.9 kg C m??2). Similarly, soil nitrogen pools amounted to 349, 269, and 240 g N m??2 for spruce, pine, 35 and birch stands, respectively. The humus layer in birch stands was thin and mixed with mineral soil, 36 and soil pH was highest in the birch stands. Spruce had the thickest humus layer with the lowest pH
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| 13. |
- Köping Olsson, Bengt, 1963-
(författare)
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Beskrivningsspråk i och för kreativ praxis : Idéutveckling under gruppsession
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Generating and developing ideas constitute centerpieces for innovations processes, idea creation methods and techniques most urgent in their initial phases processes, though the need is no less in subsequent phases. Those early phases, however, allow for more deviant ideas, characterized by more of ambiguity and uncertainty. This is an innovation process theme that is recognized as among those least understood.Through comparative studies of seven groups from three different practices, their interactions in idea development and problem solving, a deeper understanding of descriptive languages and modus operandi has been acquired. The research was carried out in three settings: brainstorming in industrial design, musical improvisation and dialogue seminars with participants representing industrial design and music, respectively. The compilation of the three practices’ contributions results in a conceptual framework. It includes such concepts as, for example, ‘momentary formation’, ‘temporary epistemology’ and ‘the play with semantic key signature’. Those concepts give examples of the reconsidering of creative group processes, relative to previous frameworks, that is a result of these studies. From the perspective of group idea, individuals’ creative processes might be perceived as the searching for the different or the deviant while we suggest that group creativity is enhanced throughits members’ abilities to preserve their own perspectives and thought styles. Group creativity is based on a willingness to focus on the central group idea while simultaneously maintaining individual thought styles.A creative group’s way of forming and mediating ideas, its modus operandi, is referred to as its description language. The importance of descriptive languages driving mechanism for creative group processes should be seen in the perspective of fundamental social cognition processes.The problem area is mapped through the strategic use of different descriptive modus. Groups employ iteration as a strategy for stimulating collective reflection, that is, to think about the problem again but in other ways. We argue that critical thinking and the ability to make critical judgements is an important driving force in the creative groups’ iterative processes: criticism makes reconsideration meaningful. Different types of criticism are discussed, as is how they interact with groups’ idea development and creative processes.This research project has resulted in a deeper understanding of the relay race of initiatives that characterizes the interactions in groups solving problems and developing ideas. The project has developed an awareness of which descriptions that stimulate group creativity.
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| 14. |
- Landin-Olsson, Mona, et al.
(författare)
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Appearance of islet cell autoantibodies after clinical diagnosis of diabetes mellitus
- 1999
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Ingår i: Autoimmunity. - : Informa UK Limited. - 0891-6934 .- 1607-842X. ; 29:1, s. 57-63
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Tidskriftsartikel (refereegranskat)abstract
- Islet cell antibodies (ICA) and glutamic acid decarboxylase antibodies (GAD65Ab) are often present at diagnosis of insulin dependent diabetes mellitus (type I diabetes) and are supposed to decline in level and frequency during the first years of disease. We have analysed ICA and GAD65Ab at onset and after one gear in 395 population based randomly selected 15-34 year old patients newly diagnosed with diabetes mellitus, to study how these autoantibodies persist, disappear and appear and their relation to C-peptide levels. Of the 395 samples 212 (54%) were positive for ICA, 250 (63%) were positive for GAD65Ab and 170 (43%) were positive for both. At follow up after one year, 27/183 (15%) of the ICA negative patients and 25/145 (17%) of the GAD65Ab negative patients had converted to positivity. Among the 103 patients negative for both ICA and GAD65Ab, 16 turned positive for one or both antibodies after one year. Patients converting to positivity for one or the other antibody after one year, had lower C-peptide levels after one year than patients who initially were and remained negative, supporting the hypothesis that these patients have a genuine type I diabetes. In conclusion, newly diagnosed patients may be negative for autoantibodies at diagnosis but develop these antibodies later on during the disease.
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| 15. |
- Littorin, Bengt, et al.
(författare)
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Family characteristics and life events before the onset of autoimmune type 1 diabetes in young adults : A nationwide study
- 2001
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 24:6, s. 1033-1037
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE - To elucidate whether family characteristics and stressful life events were associated with onset of autoimmune type 1 diabetes in young adults. RESEARCH DESIGN AND METHODS - This investigation was based on a nationwide study (Diabetes Incidence Study in Sweden) of newly diagnosed patients aged 15-34 years. Patients clinically classified as type 1 diabetic with antibodies to islet cells and/or to GAD65 were compared with age- and sex-matched control subjects via questionnaire. The questionnaire covered diabetes heredity, social environment, educational level, and life events experienced during the 12 months before diagnosis. RESULTS - The rate of response was 82% for the diabetic patients and 65% for the control subjects. Questionnaires from 349 diabetic patients and 979 control subjects were considered. Diabetes in relatives was more frequent in the patients (odds ratio [OR] 2.6) who were born in Sweden and whose mothers were of Swedish origin. No major stress factors were detected in the diabetic patients, however, in comparison with the control subjects, the diabetic patients had experienced fewer conflicts with their parents and had less often broken contacts with friends. CONCLUSIONS - Young adults with recent-onset type 1 diabetes were more exposed to heredity for diabetes, but no major prediabetic stress factors were detected. Our study does not directly support the concept that psychosocial stressful life events are involved in the development of autoimmune type 1 diabetes in young adults.
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| 16. |
- Littorin, Bengt, et al.
(författare)
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Islet cell and glutamic acid decarboxylase antibodies present at diagnosis of diabetes predict the need for insulin treatment : A cohort study in young adults whose disease was initially labeled as type 2 or unclassifiable diabetes
- 1999
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Ingår i: Diabetes Care. - : American Diabetes Association. - 0149-5992 .- 1935-5548. ; 22:3, s. 409-412
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Tidskriftsartikel (refereegranskat)abstract
- OBJECTIVE:To clarify the predictive value of islet cell antibody (ICA) and GAD65 antibody (GADA) present at diagnosis with respect to the need for insulin treatment 6 years after diagnosis in young adults initially considered to have type 2 or unclassifiable diabetes.RESEARCH DESIGN AND METHODS:The patient material was representative of the entire Swedish population, consisting of patients who were 15-34 years old at diagnosis of diabetes in 1987-1988 but were not considered to have type 1 diabetes at onset. At follow-up, 6 years after the diagnosis, it was noted whether the patient was treated with insulin. The presence of ICA was determined by an immunofluorescence assay, and GADAs were measured by a radioligand assay.RESULTS:Six years after diagnosis, 70 of 97 patients were treated with insulin, and 27 of 97 patients were treated with oral drugs or diet alone. At diagnosis, ICAs and GADAs were present in 41 (59%) of 70 patients and 41 (60%) of 68 patients, respectively, of those now treated with insulin, compared with only 1 (4%) of 26 patients and 2 (7%) of 27 patients who were still not treated with insulin. For either ICA or GADA, the corresponding frequencies were 50 (74%) of 68 for patients who were later treated with insulin and 3 (12%) of 26 for those who were still not treated with insulin, respectively. The sensitivity for later insulin treatment was highest (74%) for the presence of ICA or GADA, and the specificity was highest (100%) for ICA and GADA. The positive predictive value was 100% for the combination of ICA and GADA, 98% for ICA alone, and approximately 95% for GADA alone.CONCLUSIONS:Determination of the presence of ICA and GADA at diagnosis of diabetes improves the classification of diabetes and predicts the future need of insulin in young adults.
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| 17. |
- Moberg, Christina, et al.
(författare)
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De unga gör helt rätt när de stämmer staten
- 2022
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Ingår i: Aftonbladet. - 1103-9000.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- 1 620 forskare och lärare i forskarvärlden: Vi ställer oss bakom Auroras klimatkrav
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| 18. |
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| 19. |
- Olsson, Emma, 1974-
(författare)
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Many-body Problems in the Theory of Stellar Collapse and Neutron Stars
- 2004
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- When modelling the collapse of massive stars leading to supernova explosions and the cooling of neutron stars, understanding the microphysical processes, such as the interaction of neutrinos within a dense medium are of vital importance. The interaction of neutrinos with nucleons (neutrons and protons) is altered by the presence of the medium, compared to the same process with free nucleons. Neutrino scattering and production processes may be characterized in terms of the excitations that are created or destroyed in the nuclear medium. One way to analyse the effects of the medium is by using Landau's theory of normal Fermi liquids. This theory gives simple relationships between physical quantities such as the spin susceptibility or the response to a weak interaction probe in terms of Landau parameters, that are measures of the interaction between quasiparticles. One problem when using Landau Fermi liquid theory for nucleon matter is that the interaction has a tensor component. The tensor interaction does not conserve the total spin and, as a consequence, there are generally contributions to long-wavelength response functions from states that have more than one quasiparticle-quasihole pair in the intermediate state. Such contributions cannot be calculated in terms of Landau parameters alone, since in the usual formulation of Landau theory, only singlepair excitations are considered. In this thesis three problems are addressed. First, we obtain bounds on the contributions from more than one quasiparticle-quasihole pair by using sum-rule arguments. Second, we derive expressions for static response functions allowing for the tensor components of the interaction. We analyse which the most important effects are on the static response of nucleon matter, and find that the major contributions comes from renormalization of coupling constants and transitions to states with more than one quasiparticle-quasihole pair. Third, we show how contributions to the dynamical response coming from states containing two quasiparticle-quasihole pairs may be evaluated in terms of Landau theory if one allows for the effect of collisions in the Landau kinetic equation. We consider the case of asymmetric nuclear matter, and our work goes beyond earlier works in that they contain the effects of collisions in addition to those of the mean field.
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| 20. |
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