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- Elmståhl, Sölve, et al.
(author)
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Incidence of cerebral small vessel disease-related MR markers in the Swedish general population 'Good Aging in Skåne'(GÅS) study
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In: Journal of Neurology. - 1432-1459.
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Journal article (peer-reviewed)abstract
- BACKGROUND AND OBJECTIVES: Cerebral small vessel disease (CSVD) is associated to cognitive decline and dementia. Neuroimaging changes of CSVD are highly prevalent above 80 years. Only few studies report on incidence of CSVD in high age. We have investigated the incidence and prevalence of magnetic resonance imaging (MRI) markers of CSVD and risk factors in the general older population.METHODS: As part of the general population Good Aging in Skåne cohort study (GÅS), 241 persons (mean age 76.3 years) underwent two brain MRI, 3-T scanner with a mean interval of 5.9 years. The incidence of white matter hyperintensities (WMH), lacunar infarction, cerebral atrophies and cerebral microbleeds (CMB) were calculated and the relationship to risk factors analysed by a multivariate regression analysis. Medial temporal lobe atrophy (MTA) was graded according to Scheltens'18 scale and CMB were defined as having > 1 small (0.2-0.5 cm) hypointense lesion.RESULTS: The 6-year incidence of CMB, WMH and MTA were, 19%, 17% and 13% respectively, corresponding to 170/1,000 py., 172/1,000 py., and respectively 167/1,000 py. The incidence of CSVD according to the modified STRIVE score was 33%, 169/1,000 py and the prevalence at baseline was 73%. Moderate to high intake of alcohol was related to increased incidence of MTA and higher STRIVE score. Exposure to smoking was related to higher incidence of CMB and higher STRIVE score, adjusted for other known risk factors.CONCLUSION: CSVD is highly prevalent in the general older population and the 6-year incidence of WMH, CMB and MTA ranges from 13 to 19 percent. The modifiable lifestyle factors: smoking, and moderate alcohol intake are related to incident CSVD.
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| 3. |
- Bengtsson, Göran, et al.
(author)
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Gross nitrogen mineralization-, immobilization-, and nitrification rates as a function of soil C/N ratio and microbial activity
- 2003
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In: Soil Biology & Biochemistry. - 0038-0717. ; 35:1, s. 143-154
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Journal article (peer-reviewed)abstract
- A laboratory experiment was designed to challenge the idea that the ON ratio of forest soils may control gross N immobilization, mineralization, and nitrification rates. Soils were collected from three deciduous forests sites varying in C/N ratio between 15 and 27. They were air-dried and rewetted to induce a burst of microbial activity. The N transformation rates were calculated from an isotope dilution and enrichment procedure, in which (NH4Cl)-N-15 or (NaNO3)-N-15 was repeatedly added to the soils during 7 days of incubation. The experiments suggested that differences in gross nitrogen immobilization and mineralization rates between the soils were more related to the respiration rate and ATP content than to the C/N ratio. Peaks of respiration and ATP content were followed by high rates of mineralization and immobilization, with 1-2 days of delay. The gross immobilization of NH4+ was dependent on the gross mineralization and one to two orders of magnitude larger than the gross NO3- immobilization. The gross nitrification rates were negatively related to the ATP content and the C/N ratio and greatly exceeding the net nitrification rates. Taken together, the observations suggest that leaching of nitrate from forest soils may be largely dependent on the density and activity of the microbial community.
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| 4. |
- Falkengren-Grerup, Ursula, et al.
(author)
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Uptake capacity of amino acids by ten grasses and forbs in relation to soil acidity and nitrogen availability
- 2000
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In: Environmental and Experimental Botany. - 0098-8472. ; 44:3, s. 207-219
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Journal article (peer-reviewed)abstract
- Uptake capacity of organic nitrogen was studied in solution experiments on eight grasses and two forbs growing in acid soils with relatively high nitrogen mineralisation in southern Sweden. Uptake of a mixture of amino acids (alanine, glutamine, glycine), that varied between 1.6 and 6.3 mu mol g(-1) dw root h(-1), could not be explained by soil data from the species' field distributions (pH, total carbon and nitrogen, potential net mineralisation of ammonium and nitrate). The ratio between organic and inorganic nitrogen (methylamine) uptake was < 0.05 for the forbs, higher for the grasses with a maximum of 1.42 for Deschampsia flexuosa. The ratio was negatively correlated with measures related to soil acidity (Ellenberg's R-value, soil nitrate and total carbon) but not, as hypothesised, with the total amount of mineralised nitrogen. The total demand on nitrogen by all components of the ecosystem would probably have described the extent to which competition among and between plants and microbes induced nitrogen limitation. In a methodological study two grasses were exposed to pH 3.8, 4.5 and 6.0 and to 50, 100 and 250 mol l(-1) of three amino acids. Uptake was also compared between intact plants and excised roots. The treatment response varied considerably between the species which stresses the importance of studying intact plants at field-relevant pH and concentrations. (C) 2000 Elsevier Science B.V. All rights reserved.
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| 7. |
- Lundgren, Stefan, et al.
(author)
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Arbetsförmedlingens arbetsmarknadsutbildning : små regionala skillnader i effekter
- 2017
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Reports (other academic/artistic)abstract
- Arbetsförmedlingens Arbetsmarknadsutbildning (AUB) syftar till att ge arbetssökande bättre möjligheter att få ett arbete och samtidigt ge arbetsgivare bättre förutsättningar att få arbetssökande med lämplig kompetens. Riksrevisionen har granskat hur väl Arbetsförmedlingen lyckats med att skapa likvärdiga effekter i olika regioner för den arbetsmarknadspolitiska insatsen AUB.Granskningen visar att skillnaderna i effektstorlek mellan olika marknadsområden är relativt liten. Variationen i effekten av AUB tycks inte heller ha ökat nämnvärt efter att upphandlingen av AUB centraliserades då Arbetsförmedlingen bildades 2008.För hela landet visar resultaten att det är fler individer som två år efter avslutad AUB har en inkomst som överstiger ett prisbasbelopp, drygt 40 000 kronor, än för jämförbara arbetslösa som inte tagit del av AUB. För hela den studerade tidsperioden var andelen med en inkomst över ett prisbasbelopp cirka åtta procentenheter högre för deltagarna i AUB än för personerna i jämförelsegruppen.För att uppnå likvärdiga effekter i olika regioner rekommenderar Riksrevisionen Arbetsförmedlingen att vid effektutvärderingar av arbetsmarknadspolitiska program inkludera ett regionalt perspektiv.
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| 8. |
- Månsson, Katarina
(author)
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PLANT-BACTERIAL AND PLANT-FUNGAL COMPETITION FOR NITROGEN AND PHOSPHORUS
- 2005
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Doctoral thesis (other academic/artistic)abstract
- Competition between and within species has been one of the most studied concepts in ecology. In this thesis the aim was to test the idea of plant-microbial competition for N and, by studying this interaction, to gain a better understanding of different N processes in soil. The research carried out seeks to investigate plant-microbial competition for N based on the definition that competition only can occur when plants and soil microorganisms are mutually limited by N and use the same sources of N. Papers I to V are attempts to test the operational parts of the definition under the influence of different soil variables. It was found that, in an acidified deciduous forest soil with relatively high N mineralization rates, plants and fungi were both P limited, while the bacteria were C limited. The results also suggested that plants competed with fungi for P in this soil. The soil C:N ratio was rejected as an important factor in determining microbial N immobilization or plant-microbial competition for N, but the quality of the soil C and the soil P availability were. Furthermore, plants from deciduous forest soils with relatively high N mineralization rates have the ability to take up amino acids, such as glycine and glutamate, both in hydroponic experiments and in soil. Soil drying and rewetting affected the proportions of the N forms that were taken up by the plants and microorganisms ? plants shifted from an ammonium to an amino acid dominated uptake, while the opposite pattern was found for the microorganisms ? which may reduce the probability of competition.
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| 9. |
- Månsson, Katarina, et al.
(author)
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Plant-microbial competition for nitrogen uncoupled from soil C:N ratios
- 2009
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In: Oikos. - : Wiley. - 1600-0706 .- 0030-1299. ; 118:12, s. 1908-1916
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Journal article (peer-reviewed)abstract
- A green house experiment was designed to test the idea that competition for inorganic nitrogen (N) between plants and heterotrophic microorganisms occurs in soils with high C:N ratios, qualifying for N limited microbial activity, but not at low C:N ratios. The short- term (24 h) N-15 uptake by the grass Festuca gigantea and microorganisms in planted and unplanted soils was determined, and the bacterial activity was measured by the H-3-thymidine incorporation technique. Two deciduous forest soils, with C:N-ratios of 20 and 31, and the 20 soil amended with litter to a C:N ratio of 34, were used. A novel and important part of the experimental design was the preparation of the unplanted reference soil with plants present until the competition assay started by the addition of N-15 labelled ammonium (NH4+) or nitrate (NO3-). The results suggested that plants and soil microorganisms competed for mineral N but under influence of other factors than the soil C:N ratio. The plants reduced the microbial uptake of NH4+ and NO3- in the soil with low C:N ratio, which also had the lowest bacterial activity. The plants had a larger N uptake than microorganisms in the two natural soils but smaller in the litter-amended, and their presence enhanced the bacterial activity, especially in the latter soil. The litter-amended soil with its high C:N ratio and easily decomposable C was the soil that best fulfilled the criteria for competition, including a net consumption of mineral N during the assay, the lowest plant uptake of mineral N due to the high N immobilization by microorganisms, and a reduced microbial N-15 uptake-to-bacterial activity in the presence of plants. Thus, other factors, such as the decomposability of the soil C and the bacterial activity, were more important than the soil C:N ratio to the outcome of plant-microbial competition for N.
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| 10. |
- Månsson, Katarina, et al.
(author)
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Soil moisture variations affect short-term plant-microbial competition for ammonium, glycine, and glutamate.
- 2014
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In: Ecology and Evolution. - : Wiley. - 2045-7758. ; 4:7, s. 1061-1072
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Journal article (peer-reviewed)abstract
- We tested whether the presence of plant roots would impair the uptake of ammonium ([Formula: see text]), glycine, and glutamate by microorganisms in a deciduous forest soil exposed to constant or variable moisture in a short-term (24-h) experiment. The uptake of (15)NH4 and dual labeled amino acids by the grass Festuca gigantea L. and soil microorganisms was determined in planted and unplanted soils maintained at 60% WHC (water holding capacity) or subject to drying and rewetting. The experiment used a design by which competition was tested in soils that were primed by plant roots to the same extent in the planted and unplanted treatments. Festuca gigantea had no effect on microbial N uptake in the constant moist soil, but its presence doubled the microbial [Formula: see text] uptake in the dried and rewetted soil compared with the constant moist. The drying and rewetting reduced by half or more the [Formula: see text] uptake by F. gigantea, despite more than 60% increase in the soil concentration of [Formula: see text]. At the same time, the amino acid and [Formula: see text]-N became equally valued in the plant uptake, suggesting that plants used amino acids to compensate for the lower [Formula: see text] acquisition. Our results demonstrate the flexibility in plant-microbial use of different N sources in response to soil moisture fluctuations and emphasize the importance of including transient soil conditions in experiments on resource competition between plants and soil microorganisms. Competition between plants and microorganisms for N is demonstrated by a combination of removal of one of the potential competitors, the plant, and subsequent observations of the uptake of N in the organisms in soils that differ only in the physical presence and absence of the plant during a short assay. Those conditions are necessary to unequivocally test for competition.
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