| 1. |
- Kumarathunge, Dushan P., et al.
(författare)
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Acclimation and adaptation components of the temperature dependence of plant photosynthesis at the global scale
- 2019
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Ingår i: New Phytologist. - : John Wiley & Sons. - 0028-646X .- 1469-8137. ; 222:2, s. 768-784
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Tidskriftsartikel (refereegranskat)abstract
- The temperature response of photosynthesis is one of the key factors determining predicted responses to warming in global vegetation models (GVMs). The response may vary geographically, owing to genetic adaptation to climate, and temporally, as a result of acclimation to changes in ambient temperature. Our goal was to develop a robust quantitative global model representing acclimation and adaptation of photosynthetic temperature responses.We quantified and modelled key mechanisms responsible for photosynthetic temperature acclimation and adaptation using a global dataset of photosynthetic CO2 response curves, including data from 141 C3 species from tropical rainforest to Arctic tundra. We separated temperature acclimation and adaptation processes by considering seasonal and common-garden datasets, respectively.The observed global variation in the temperature optimum of photosynthesis was primarily explained by biochemical limitations to photosynthesis, rather than stomatal conductance or respiration. We found acclimation to growth temperature to be a stronger driver of this variation than adaptation to temperature at climate of origin.We developed a summary model to represent photosynthetic temperature responses and showed that it predicted the observed global variation in optimal temperatures with high accuracy. This novel algorithm should enable improved prediction of the function of global ecosystems in a warming climate.
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| 2. |
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| 3. |
- Ahlberg, Erik, et al.
(författare)
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"Vi klimatforskare stödjer Greta och skolungdomarna"
- 2019
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Ingår i: Dagens nyheter (DN debatt). - 1101-2447.
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Tidskriftsartikel (populärvet., debatt m.m.)abstract
- DN DEBATT 15/3. Sedan industrialiseringens början har vi använt omkring fyra femtedelar av den mängd fossilt kol som får förbrännas för att vi ska klara Parisavtalet. Vi har bara en femtedel kvar och det är bråttom att kraftigt reducera utsläppen. Det har Greta Thunberg och de strejkande ungdomarna förstått. Därför stödjer vi deras krav, skriver 270 klimatforskare.
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| 4. |
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| 5. |
- Jakobsson, Martin, 1966-, et al.
(författare)
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An Arctic Ocean ice shelf during MIS 6 constrained by new geophysical and geological data
- 2010
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 29:25-26, s. 3505-3517
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Tidskriftsartikel (refereegranskat)abstract
- The hypothesis of floating ice shelves covering the Arctic Ocean during glacial periods was developed in the 1970s. In its most extreme form, this theory involved a 1000 m thick continuous ice shelf covering the Arctic Ocean during Quaternary glacial maxima including the Last Glacial Maximum (LGM). While recent observations clearly demonstrate deep ice grounding events in the central Arctic Ocean, the ice shelf hypothesis has been difficult to evaluate due to a lack of information from key areas with severe sea ice conditions. Here we present new data from previously inaccessible, unmapped areas that constrain the spatial extent and timing of marine ice sheets during past glacials. These data include multibeam swath bathymetry and subbottom profiles portraying glaciogenic features on the Chukchi Borderland, southern Lomonosov Ridge north of Greenland, Morris Jesup Rise, and Yermak Plateau. Sediment cores from the mapped areas provide age constraints on the glaciogenic features. Combining these new geophysical and geological data with earlier results suggests that an especially extensive marine ice sheet complex, including an ice shelf, existed in the Amerasian Arctic Ocean during Marine Isotope Stage (MIS) 6. From a conceptual oceanographic model we speculate that the cold halocline of the Polar Surface Water may have extended to deeper water depths during MIS 6 inhibiting the warm Atlantic water from reaching the Amerasian Arctic Ocean and, thus, creating favorable conditions for ice shelf development. The hypothesis of a continuous 1000 m thick ice shelf is rejected because our mapping results show that several areas in the central Arctic Ocean substantially shallower than 1000 m water depth are free from glacial influence on the seafloor.
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| 6. |
- Wallin, Paul, 1961-, et al.
(författare)
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Re-dating Ahu Nau Nau and the Settlement at 'Anakena, Rapa Nui
- 2010
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Ingår i: The Gotland Papers. - Visby : Gotland University. - 9789186343071 ; , s. 37-46
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The building phase and early use of Ahu Nau Nau have been re-dated by nine charcoal and rat bone samples. The new dates in comparison with earlier data suggest that the ahu was constructed around 650-550 BP. It is also suggested that a settlement dated to c. 950-900 BP preceded the ahu-building phase. A new question in light of recent research might be raised: Is the earliest settlement on Rapa Nui found at ´Anakena or should we look elsewhere?
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| 7. |
- Abraham-Nordling, Mirna, et al.
(författare)
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Incidence of hyperthyroidism in Sweden
- 2011
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Ingår i: European Journal of Endocrinology. - 0804-4643 .- 1479-683X. ; 165:6, s. 899-905
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: The incidence of hyperthyroidism has been reported in various countries to be 23-93/100000 inhabitants per year. This extended study has evaluated the incidence for similar to 40% of the Swedish population of 9 million inhabitants. Sweden is considered to be iodine sufficient country. Methods:All patients including children, who were newly diagnosed with overt hyperthyroidism in the years 2003-2005, were prospectively registered in a multicenter study. The inclusion criteria are as follows:clinical symptoms and/or signs of hyperthyroidism with plasma TSH concentration below 0.2 mIE/l and increased plasma levels of free/total triiodothyronine and/or free/total thyroxine. Patients with relapse of hyperthyroidism or thyroiditis were not included. The diagnosis of Graves' disease (GD), toxic multinodular goiter (TMNG) and solitary toxic adenoma (STA), smoking, initial treatment, occurrence of thyroid-associated eye symptoms/signs, and demographic data were registered. Results:A total of 2916 patients were diagnosed with de novo hyperthyroidism showing the total incidence of 27.6/100 000 inhabitants per year. The incidence of GD was 21.0/100 000 and toxic nodular goiter (TNG=STA+TMNG) occurred in 692 patients, corresponding to an annual incidence of 6.5/100 000. The incidence was higher in women compared with men (4.2:1). Seventy-five percent of the patients were diagnosed with GD, in whom thyroid-associated eye symptoms/signs occurred during diagnosis in every fifth patient. Geographical differences were observed. Conclusion:The incidence of hyperthyroidism in Sweden is in a lower range compared with international reports. Seventy-five percent of patients with hyperthyroidism had GD and 20% of them had thyroid-associated eye symptoms/signs during diagnosis. The observed geographical differences require further studies.
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| 8. |
- af Ekenstam, Angelica, et al.
(författare)
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Leaf respiration rates are increased by warm season as well as by elevated temperature treatment in Eucalyptus globulus
- 2014
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Ingår i: EGU General Assembly 2014, held 27 April - 2 May, 2014 in Vienna, Austria.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Plant leaf respiration is one of the major CO2 fluxes between terrestrial biosphere and the atmosphere, and its responses to elevated CO2 and temperature thus have important implications for the carbon cycle and rate on ongoing climate change. Non-photorespiratory leaf respiration is reduced in light, Rlight, compared with the rate in the dark, Rdark. It is therefore important to consider both Rlight and Rdark when estimating the exchange of CO2 between the biosphere and the atmosphere, during current and future climates. This study was conducted at the Hawkesbury Forest Experiment, HFE, in Richmond, NSW, Australia. Trees of Tasmanian Blue Gum (Eucalyptus globulus Labill.) were exposed in whole tree chambers (WTC) to a complete factorial combination of ambient and elevated temperature and CO2 (+3 °C and +240 ppm CO2, respectively). The measurements of Rlight and Rdark were made in 2011 after 15 month exposure in the WTCs. The measurements were made in March (after the year’s hottest months) and October (after the coldest period). Rlight was determined at four temperatures ranging between 20 and 40 °C on attached leaves using a portable gas exchange system (LI-6400XT). Rdark was measured at 20-40 °C in October and at 25 °C in March. Rdark was measured after dark acclimation for at least 30 min and Rlight was determined from the intersection of the photosynthetic CO2 responses measured at three different light intensities using the Laisk metod. Trees grown in elevated temperature had a considerably higher Rdark (+53% across all measurement temperatures in October). However, Rlight did not respond significantly to either CO2 or temperature. In October, the Rlight to Rdark ratio indicated an overall light inhibition of respiration of 31% across all temperatures and in March the light inhibition was 22 % at 25 °C. The seasonal comparisons showed that both Rlight and Rdark were considerably higher after the warm compared to cold season, especially when measured at high temperature. These results points out the importance to account for Rlight as well as seasonal thermal respiratory acclimation when improving predictions of the carbon exchange between tree canopies and the atmosphere. If not taking light inhibition into account, leaf respiration is being overestimated and if not taking the seasonal acclimation into account the errors are potentially very large.
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| 9. |
- Ahl, Rebecka, 1987-, et al.
(författare)
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Does beta-blockade reduce the risk of depression in patients with isolated severe extracranial injuries?
- 2017
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Ingår i: World Journal of Surgery. - New York : Springer. - 0364-2313 .- 1432-2323. ; 41:7, s. 1801-1806
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Approximately half of trauma patients develop post-traumatic depression. It is suggested that beta-blockade impairs trauma memory recollection, reducing depressive symptoms. This study investigates the effect of early beta-blockade on depression following severe traumatic injuries in patients without significant brain injury.METHODS: Patients were identified by retrospectively reviewing the trauma registry at an urban university hospital between 2007 and 2011. Severe extracranial injuries were defined as extracranial injuries with Abbreviated Injury Scale score ≥3, intracranial Abbreviated Injury Scale score <3 and an Injury Severity Score ≥16. In-hospital deaths and patients prescribed antidepressant therapy ≤1 year prior to admission were excluded. Patients were stratified into groups based on pre-admission beta-blocker status. The primary outcome was post-traumatic depression, defined as receiving antidepressants ≤1 year following trauma.RESULTS: Five hundred and ninety-six patients met the inclusion criteria with 11.4% prescribed pre-admission beta-blockade. Patients receiving beta-blockers were significantly older (57 ± 18 vs. 42 ± 17 years, p < 0.001) with lower Glasgow Coma Scale score (12 ± 3 vs. 14 ± 2, p < 0.001). The beta-blocked cohort spent significantly longer in hospital (21 ± 20 vs. 15 ± 17 days, p < 0.01) and intensive care (4 ± 7 vs. 3 ± 5 days, p = 0.01). A forward logistic regression model was applied and predicted lack of beta-blockade to be associated with increased risk of depression (OR 2.7, 95% CI 1.1-7.2, p = 0.04). After adjusting for group differences, patients lacking beta-blockers demonstrated an increased risk of depression (AOR 3.3, 95% CI 1.2-8.6, p = 0.02).CONCLUSIONS: Pre-admission beta-blockade is associated with a significantly reduced risk of depression following severe traumatic injury. Further investigation is needed to determine the beneficial effects of beta-blockade in these instances.
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| 10. |
- Ahl, Rebecka, 1987-
(författare)
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The Association Between Beta-Blockade and Clinical Outcomes in the Context of Surgical and Traumatic Stress
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Traumatic injury and major abdominal surgery are areas in general surgery associated with high rates of morbidity and mortality. The overall colorectal cancer surgery mortality rate is around 4%, with that for emergency surgery more than twice as high as for planned. Surgical morbidity varies between 25% and 45%. Around half of trauma patients develop low mood. In one quarter of patients this becomes permanent. Depression is known to impede physical rehabilitation and recovery. The onset of physiological stress, driven by adrenergic hyperactivity following traumatic and surgical injury is hypothesized to contribute to these adverse outcomes. Interest has therefore been sparked into blocking adrenergic receptor activation.Papers I and II investigated the role of beta-blocker therapy in preventing post-traumatic depression following severe traumatic brain injury (Paper I) and severe extracranial injury (Paper II). The Karolinska University Hospital Trauma Registry was used to identify patients admitted between 2007 and 2011. In Paper I (n = 545), patients on pre-injury beta-blocker therapy were matched to beta-blocker naïve patients with equivalent injury burden. Results revealed that beta-blocked patients exhibited a 60% reduced risk of needing antidepressant therapy within one year of trauma. In Paper II (n = 596), the lack of beta-blocker use before extracranial trauma was linked to a three-fold increase in the risk of antidepressant initiation.Papers III-V explored the role of pre-operative beta-blocker therapy in patients undergoing surgery for colorectal cancer between 2007 and 2016, identified using the nationwide Swedish Colorectal Cancer Registry. Paper III (n = 3,187) identified a 69% reduction in the risk of 30-day mortality in beta-blocked patients. Paper IV (n = 22,337) outlined long-term survival benefits for patients on beta-blocker therapy prior to undergoing elective surgery for colon cancer. Beta-blocked patients showed a risk reduction of 42% for 1-year all-cause mortality and 18% for 5-year cancerspecific mortality. Similarly, patients on beta-blocker therapy who underwent surgery for rectal cancer demonstrated improved survival up to one year after surgery with a risk reduction of 57% and a reduction in anastomotic failure and infectious complications in Paper V (n = 11,966).
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