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- Sigurdsson, Bjarni D., et al.
(författare)
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Geothermal ecosystems as natural climate change experiments : The ForHot research site in Iceland as a case study
- 2016
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Ingår i: Icelandic Agricultural Sciences. - 1670-567X. ; 29:1, s. 53-71
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Tidskriftsartikel (refereegranskat)abstract
- This article describes how natural geothermal soil temperature gradients in Iceland have been used to study terrestrial ecosystem responses to soil warming. The experimental approach was evaluated at three study sites in southern Iceland one grassland site that has been warm for at least 50 years (GO), and another comparable grassland site (GN) and a Sitka spruce plantation (FN) site that have both been warmed since an earthquake took place in 2008. Within each site type, five ca. 50 m long transects, with six permanent study plots each, were established across the soil warming gradients, spanning from unwarmed control conditions to gradually warmer soils. It was attempted to select the plots so the annual warming levels would be ca. +1, +3, +5, +10 and +20 °C within each transect. Results of continuous measurements of soil temperature (Ts) from 2013-2015 revealed that the soil warming was relatively constant and followed the seasonal Ts cycle of the unwarmed control plots. Volumetric water content in the top 5 cm of soil was repeatedly surveyed during 2013-2016. The grassland soils were wetter than the FN soils, but they had sometimes some significant warming-induced drying in the surface layer of the warmest plots, in contrast to FN. Soil chemistry did not show any indications that geothermal water had reached the root zone, but soil pH did increase somewhat with warming, which was probably linked to vegetation changes. As expected, the potential decomposition rate of organic matter increased significantly with warming. It was concluded that the natural geothermal gradients at the ForHot sites in Iceland offered realistic conditions for studying terrestrial ecosystem responses to warming with minimal artefacts.
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- Thorleifsdottir, Ragna H., et al.
(författare)
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Throat Infections are Associated with Exacerbation in a Substantial Proportion of Patients with Chronic Plaque Psoriasis
- 2016
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Ingår i: Acta Dermato-Venereologica. - : Medical Journals Sweden AB. - 0001-5555 .- 1651-2057. ; 96:6, s. 788-791
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Tidskriftsartikel (refereegranskat)abstract
- Streptococcal throat infections are known to trigger or exacerbate psoriasis, and several studies support the benefit of tonsillectomy. To evaluate the potential of tonsillectomy as a treatment, we used a retrospective study-specific questionnaire to assess the proportion of psoriasis patients with sore throat-associated psoriasis exacerbations. Our survey sampled 275 psoriasis patients. Of patients with plaque psoriasis, 42% reported sore throat-associated psoriasis exacerbations, and of patients with confirmed streptococcal infections, 72% reported aggravation. Notably, women and patients with early onset psoriasis were more likely to report psoriasis exacerbation after a sore throat (p< 0.001, p = 0.046, respectively). Other psoriasis aggravation factors were more common in patients with sore throat-associated exacerbations (p < 0.01). Of tonsillectomized patients, 49% reported subsequent improvement and had more frequent sore throat -associated aggravation of psoriasis than patients who did not improve after tonsillectomy (p=0.015). These findings suggest a closer association between sore throats, streptococcal throat infections and plaque psoriasis than reported previously.
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