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2. |
- Blanck, Sara, 1980-
(författare)
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Elever möter samhällsfrågor : Didaktiska och bildningsteoretiska perspektiv på samhällsorienterande undervisning om epoktypiska samhällsfrågor
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Med utgångspunkt i didaktik och bildningsteoretiska perspektiv är syftet med denna avhandling att undersöka och analysera ämnesövergripande undervisning om epoktypiska samhällsfrågor i grundskolan för att utveckla kunskap om undervisningens didaktiska möjligheter och utmaningar.Avhandlingen är en sammanläggning och består av tre ingående texter: en licentiatuppsats om samhällskunskapsämnet i ämnesintegrerad undervisning som genomfördes 2012–2014 samt två artiklar från forskningsprojektet ”Att utveckla undervisning i samhällsfrågor: om didaktiska val i SO-ämnena i grundskolans mellanår 4-6” som genomfördes 2017–2022. I de empiriska undersökningarna användes olika metoder såsom observationer och ljudinspelning av undervisning, intervjuer med lärare, enkät, fokusgruppsintervjuer med elever samt forsknings- och utvecklingscirkel tillsammans med lärare. Vid analysen används didaktiska och bildningsteoretiska perspektiv för att analysera empirin. Resultaten presenteras i form av så kallade curriculumprinciper som kan fungera som utgångspunkter för lärares didaktiska analys, val och handlingar, när det kommer till undervisning om epoktypiska samhällsfrågor. Genom en analys av de didaktiska relationerna visas betydelsen av att lärarens didaktiska val görs utifrån ett relevant och kraftfullt innehåll som också blir meningsfullt för elevers samtid och framtid. Fyra curriculumprinciper föreslås som utgångspunkter för lärare när de planerar och genomför undervisning om epoktypiska samhällsfrågor. De två första principerna handlar om hur ett flerdimensionellt bildningsbegrepp, där kognitiva, etiska och estetiska dimensioner samverkar, kan utgöra en målsättning för undervisningen. Innehållet kan struktureras i ämnessamspel med skolämnenas olika bidrag till förståelsen av dessa komplexa samhällsfrågor. Den tredje och fjärde principen har utgångspunkt i dels elevers begreppsliga utveckling genom autentiska exempel och inferenser dels i hur lärares didaktiska val av exempel blir betydelsefulla för hur innehållet förstås av eleverna.
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3. |
- Modig, Niclas, 1973-
(författare)
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Hur kan ekonomi göras begripligt? : En studie om villkor för kraftfull ekonomiundervisning i samhällskunskap
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis seeks to understand what constitutes important economics knowledge from a disciplinary perspective and how such knowledge is recontextualized in textbooks and teacher training to become teachable to social studies students in Sweden’s upper secondary schools. It consists of four substudies: two covering disciplinary economics knowledge and two covering preservice social studies teachers. The first and second substudies focus on disciplinary economics knowledge. The first substudy, which was based on an online questionnaire for Swedish economics scholars at higher education institutions, shows that six economics terms/principles are especially important for people to understand. Such knowledge may be considered powerful economics knowledge. The second substudy demonstrates that there are great variations in the extent to which powerful economics terms appear in Swedish social studies textbooks and in how the language used shifts between everyday and scientific language. There is a risk that not all learners are given equal preconditions to develop economics knowledge through social studies textbooks. The third and fourth substudies focus on how preservice social studies teachers develop the ability to teach economic knowledge and show that students’ individual pedagogical content knowledge (PCK) depends on theoretical and practical studies. Students are unconfident about their economics knowledge, which may negatively affect their willingness and ability to teach economics when they become in-service social studies teachers.Overall, there appears to be a problem with the recontextualization of economics knowledge in Swedish social studies textbooks and with economics education for preservice social studies teachers. This may negatively affect economics education. As a result, it is important to strengthen preservice social studies teachers’ economics knowledge through increased economics content during teacher training. The importance of imparting powerful economics knowledge and shifting between everyday and scientific language in textbooks and during teaching needs to be highlighted for policymakers, textbook authors, and teacher educators.
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4. |
- Möller, Per, et al.
(författare)
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Deglaciation history and subsequent lake dynamics in the Siljan region, south-central Sweden, based on new LiDAR evidence and sediment records
- 2022
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Ingår i: Earth Surface Processes and Landforms. - : Wiley. - 0197-9337 .- 1096-9837. ; 47, s. 3515-3545
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Tidskriftsartikel (refereegranskat)abstract
- The Siljan region hosts Europe´s largest impact structure. The high-relief landscape, with a central granite dome bordered by lake basins, contains an array of glacial and shore-level landforms. We investigated its deglaciation history by mapping and analysing landforms on high resolution LiDAR-based Digital Surface Models coupled with well-dated sediment successions from peat and lake sediment cores. The granite dome and bordering areas are characterized by streamlined terrain and ribbed moraine with a streamlined overprint. These suggest an ice-flow direction from NNW with wet-based thermal conditions prior to deglaciation. During its retreat, the ice sheet was split into thinner plateau ice and thicker basin ice. Sets of low-gradient glaciofluvial erosion channels suggest intense ice-lateral meltwater drainage across gradually ice-freed slopes, while 'down-the-slope' erosion channels and eskers show meltwater drainage from stagnated plateau ice. Thick basin ice receded with a subaqueous margin across the deep Siljan–Orsasjön Basin c. 10,700–10,500 cal. BP. During ice recession the ingression of the Baltic Ancylus Lake led to diachronous formation of highest shoreline marks, from c. 207 m in the south to c. 220 m a.s.l. in the north. Differential uplift resulted in shallowing of the water body, which led to the isolation of the Siljan–Orsasjön Basin from the Baltic Basin at c. 9800 cal. BP. The post-isolation water body – the ‘Ancient Lake Siljan' – was drained through the ancient Åkerö Channel with a water level at 168–169 m a.s.l. during c. 1000 years. A later rerouting of the outlet to the present course was initiated at c. 8800 cal. BP, which led to a lake-level lowering of 6–7 m to today’s level of Lake Siljan (c. 162 m a.s.l.). This study shows the strength of an integrated methodological approach for deciphering the evolution of a complex landscape, combining highly resolved geomorphological analysis with well-dated sediment successions.
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5. |
- Möller, Per, et al.
(författare)
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Deglaciation history and subsequent lake dynamics in the Siljan region, south-central Sweden - LiDAR evidence and sediment records
- 2024
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The Siljan region hosts Europe´s largest impact structure. The high-relief landscape, with a central granite dome bordered by lake basins, contains an array of glacial and shore-level landforms. We investigated its deglaciation history by mapping and analysing landforms on high resolution LiDAR-based Digital Surface Models coupled with well-dated sediment successions from peat and lake sediment cores. The granite dome and bordering areas are characterized by streamlined terrain and ribbed moraine with a streamlined overprint. These suggest an ice-flow direction from NNW with wet-based thermal conditions prior to deglaciation. During its retreat, the ice sheet was split into thinner plateau ice and thicker basin ice. Sets of low-gradient glaciofluvial erosion channels suggest intense ice-lateral meltwater drainage across gradually ice-freed slopes, while 'down-the-slope' erosion channels and eskers show meltwater drainage from stagnated plateau ice. Thick basin ice receded with a subaqueous margin across the deep Siljan–Orsasjön Basin c. 10,700–10,500 cal. BP. During ice recession the ingression of the Baltic Ancylus Lake led to diachronous formation of highest shoreline marks, from 207 m in the south to 220 m a.s.l. in the north. Differential uplift resulted in shallowing of the water body, which led to the isolation of the Siljan¬–Orsasjön Basin from the Baltic Basin at c. 9800 cal. BP. The post-isolation water body – the ‘Ancient Lake Siljan' – was drained through the ancient Åkerö Channel with a water level at 168–169 m a.s.l. during c. 1000 years. A later rerouting of the outlet to the present course was initiated at c. 8800 cal. BP, which led to a lake-level lowering of 6–7 m to today’s level of Lake Siljan (162 m a.s.l.). This study shows the strength of an integrated methodological approach for deciphering the evolution of a complex landscape, combining highly resolved geomorphological analysis with well-dated sediment successions.
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6. |
- Thorén, Anna, et al.
(författare)
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Rapid response team activation prior to in-hospital cardiac arrest: Areas for improvements based on a national cohort study
- 2023
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Ingår i: Resuscitation. - 0300-9572 .- 1873-1570. ; 193
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Rapid response teams (RRTs) are designed to improve the "chain of prevention" of in-hospital cardiac arrest (IHCA). We studied the 30-day survival of patients reviewed by RRTs within 24 hours prior to IHCA, as compared to patients not reviewed by RRTs.Methods: A nationwide cohort study based on the Swedish Registry of Cardiopulmonary Resuscitation, between January 1st, 2014, and December 31st, 2021. An explorative, hypothesis-generating additional in-depth data collection from medical records was performed in a small subgroup of general ward patients reviewed by RRTs.Results: In all, 12,915 IHCA patients were included. RRT-reviewed patients (n = 2,058) had a lower unadjusted 30-day survival (25% vs 33%, p < 0.001), a propensity score based Odds ratio for 30-day survival of 0.92 (95% Confidence interval 0.90-0.94, p < 0.001) and were more likely to have a respiratory cause of IHCA (22% vs 15%, p < 0.001). In the subgroup (n = 82), respiratory distress was the most common RRT trigger, and 24% of the RRT reviews were delayed. Patient transfer to a higher level of care was associated with a higher 30-day survival rate (20% vs 2%, p < 0.001).Conclusion: IHCA preceded by RRT review is associated with a lower 30-day survival rate and a greater likelihood of a respiratory cause of cardiac arrest. In the small explorative subgroup, respiratory distress was the most common RRT trigger and delayed RRT activation was frequent. Early detection of respiratory abnormalities and timely interventions may have a potential to improve outcomes in RRT-reviewed patients and prevent further progress into IHCA.
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7. |
- Andersson, Axel G, et al.
(författare)
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High Exposure to Perfluoroalkyl Substances and Antibody Responses to SARS-CoV-2 mRNA Vaccine-an Observational Study in Adults from Ronneby, Sweden.
- 2023
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Ingår i: Environmental health perspectives. - 1552-9924. ; 131:8
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Tidskriftsartikel (refereegranskat)abstract
- Per- and polyfluoroalkyl substances (PFAS) are widely used, environmentally ubiquitous, and stable chemicals that have been associated with lower vaccine-induced antibody responses in children; however, data on adults are limited. The drinking water from one of the two waterworks in Ronneby, Sweden, was heavily contaminated for decades with PFAS from firefighting foams, primarily perfluorohexane sulfonic acid and perfluorooctanesulfonic acid (PFOS). Vaccination against SARS-CoV-2 offered a unique opportunity to investigate antibody responses to primary vaccination in adults who had been exposed to PFAS.Our objective was to evaluate associations between PFAS, across a wide range of exposure levels, and antibody responses in adults 5 wk and 6 months after a two-dose vaccination regime against SARS-CoV-2.Adults age 20-60 y from Ronneby (n=309, median PFOS serum level 47ng/mL, fifth to 95th percentile 4-213ng/mL) and a group with background exposure (n=47, median PFOS serum level 4ng/mL) received two doses of the Spikevax (Moderna) mRNA vaccine. The levels of seven PFAS were measured in serum before vaccination. Serum immunoglobulin G antibodies against the SARS-CoV-2 spike antigen (S-Abs) were measured before vaccination and at 5 wk (n=350) and 6 months (n=329) after the second vaccine dose. Linear regression analyses were fitted against current, historical, and prenatal exposure to PFAS, adjusting for sex, age, and smoking, excluding individuals with previous SARS-CoV-2-infection.PFAS exposure, regardless of how it was estimated, was not negatively associated with antibody levels 5 wk [current PFOS: -0.5% S-Abs/PFOS interquartile range (IQR); 95% confidence interval (CI): -8, 7] or 6 months (current PFOS: 3% S-Abs/PFOS IQR; 95% CI: -6, 12) after COVID-19 vaccination.Following a strict study protocol, rigorous study design, and few dropouts, we found no indication that PFAS exposure negatively affected antibody responses to COVID-19 mRNA vaccination for up to 6 months after vaccination. https://doi.org/10.1289/EHP11847.
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8. |
- Auffret, Alistair G., et al.
(författare)
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More warm-adapted species in soil seed banks than in herb layer plant communities across Europe
- 2023
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Ingår i: Journal of Ecology. - : John Wiley & Sons. - 0022-0477 .- 1365-2745. ; 111:5, s. 1009-1020
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Tidskriftsartikel (refereegranskat)abstract
- Responses to climate change have often been found to lag behind the rate of warming that has occurred. In addition to dispersal limitation potentially restricting spread at leading range margins, the persistence of species in new and unsuitable conditions is thought to be responsible for apparent time-lags. Soil seed banks can allow plant communities to temporarily buffer unsuitable environmental conditions, but their potential to slow responses to long-term climate change is largely unknown. As local forest cover can also buffer the effects of a warming climate, it is important to understand how seed banks might interact with land cover to mediate community responses to climate change. We first related species-level seed bank persistence and distribution-derived climatic niches for 840 plant species. We then used a database of plant community data from grasslands, forests and intermediate successional habitats from across Europe to investigate relationships between seed banks and their corresponding herb layers in 2763 plots in the context of climate and land cover. We found that species from warmer climates and with broader distributions are more likely to have a higher seed bank persistence, resulting in seed banks that are composed of species with warmer and broader climatic distributions than their corresponding herb layers. This was consistent across our climatic extent, with larger differences (seed banks from even warmer climates relative to vegetation) found in grasslands. Synthesis. Seed banks have been shown to buffer plant communities through periods of environmental variability, and in a period of climate change might be expected to contain species reflecting past, cooler conditions. Here, we show that persistent seed banks often contain species with relatively warm climatic niches and those with wide climatic ranges. Although these patterns may not be primarily driven by species’ climatic adaptations, the prominence of such species in seed banks might still facilitate climate-driven community shifts. Additionally, seed banks may be related to ongoing trends regarding the spread of widespread generalist species into natural habitats, while cool-associated species may be at risk from both short- and long-term climatic variability and change.
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9. |
- Bauer, Susanne
(författare)
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Cell type-specific translatome analysis of mouse models of three genetic neurodegenerative diseases
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The burden neurodegenerative diseases place on patients, their loved ones, and the healthcare system is significant, and despite extensive research efforts, there is currently no cure. Since degenerative changes in the brain can begin years before symptoms appear, early intervention is critical. Additionally, neurodegenerative diseases target certain brain regions and neuron types early on. A more comprehensive understanding of the affected cells during the presymptomatic phase is therefore crucial for an effective and targeted intervention. Herein, we isolated, sequenced, and analyzed translatome samples from six neuronal cell types in knock-in mouse models of three monogenic neurodegenerative diseases at a presymptomatic stage: genetic Creutzfeldt-Jakob disease (gCJD), fatal familial insomnia (FFI), and Huntington’s disease (HD). To obtain the translatome samples, we used RiboTag to immunoprecipitate HA-tagged ribosomes with their translating mRNAs from targeted cell types. We analyzed six cell types across two brain regions: cerebral and cerebellar glutamatergic and GABAergic neurons, and cerebral parvalbumin (PV) and somatostatin (SST)-expressing neurons. In the first paper, we focused our analysis on the prion diseases, gCJD (E200K) and FFI (D178N). Here observed a similar response of SST+ neurons, a cell type not previously reported as affected, in both disease models. This was characterized by upregulation of ribosomeassociated genes, and downregulation of cytoskeleton and synapse-associated genes in FFI. Weighted gene co-expression network analysis of SST+ neurons pointed towards the downregulation of mTOR inhibition as a potential mechanism underlying the observed gene expression changes. In the second paper, we analyzed a 129S4-HdhQ200 knock-in mouse model of HD. Histological and behavioral assessment revealed pathological changes in the striatum and cerebellum at 9 months and a later, mild behavioral phenotype. Translatome analysis indicated a surprisingly strong response in reportedly resistant glutamatergic neurons of the cerebellum, marked by upregulation of cell cycle regulators Ccnd1 and chromobox protein genes. In the third paper, we aimed to compare disease-specific responses of PV+ neurons across the three disease models. This analysis revealed a milder response in HD compared to prion disease at comparable disease stages. Functional analysis further indicated PV+ neurons may respond differently in the investigated diseases, showing upregulation of immune response-associated pathways in gCJD, neurodegenerative-disease pathways in FFI, and autophagy in HD. Lastly, the generation of mouse models such as were used in papers I-III requires stable and predictable transgene expression without interfering with the expression of endogenous genes. In the fourth paper, we conducted a pilot study to compare three potential loci, Rpl6, Rpl7, and Eef1a1, as potential safe harbors for transgene integration. Preliminary results indicated that the Rpl6 locus may be best suited for our purposes. Furthermore, this work generated a novel dataset consisting of translatome profiles of six cell types in three neurodegenerative disease models. This provides gene expression data at a previously unavailable level of cellular resolution, especially in prion disease. We believe that this data will serve as a valuable resource for future research and help expand our understanding of the early molecular mechanisms in neurodegenerative disease beyond the scope of this thesis.
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10. |
- Björklund, Mattias, 1971-
(författare)
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Beyond Moral Teaching : Financial Literacy as Citizenship Education
- 2021
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This thesis explores what financial literacy is, what financial literacy becomes and what financial literacy could become within the context of a citizenship education such as the Swedish upper secondary subject of social studies. Financial literacy does not intuitively converge with social sciences which leaves social studies teachers to both teach and realise financial literacy. Thus, teachers become co-creators of financial literacy as a school subject. This thesis explores this process via two different studies resulting in four research articles. In the first study, semi-structured interviews – analysed through PCK – are used to explore the perceptions of Swedish social studies teachers in upper secondary school regarding financial literacy teaching and learning. The findings include differences between experienced and novice teachers regarding which content knowledge and pedagogical approaches they use. However, all teachers express difficulties fitting financial literacy into social studies, mainly due to a perception of financial literacy primarily being a private matter, along with the unclear relationship between financial and societal issues. The second study is designed as a financial literacy teaching intervention. Students’ views on a financial dilemma are analysed using citizenship conceptions and threshold concepts. The findings are used to discuss design principles for financial literacy teaching. Salient conclusions in the thesis include citizenship education being able to frame financial literacy and provide epistemic features which can make financial literacy more teachable and learnable. It is hoped that the results from this thesis can inform future financial literacy teaching design as well as policy discussion related to financial literacy teaching and learning contextualised with another subject, especially citizenship education.
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11. |
- Bradshaw, Clare, et al.
(författare)
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Physical Disturbance by Bottom Trawling Suspends Particulate Matter and Alters Biogeochemical Processes on and Near the Seafloor
- 2021
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 8
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Tidskriftsartikel (refereegranskat)abstract
- Bottom trawling is known to affect benthic faunal communities but its effects on sediment suspension and seabed biogeochemistry are less well described. In addition, few studies have been carried out in the Baltic Sea, despite decades of trawling in this unique brackish environment and the frequent occurrence of trawling in areas where hypoxia and low and variable salinity already act as ecosystem stressors. We measured the physical and biogeochemical impacts of an otter trawl on a muddy Baltic seabed. Multibeam bathymetry revealed a 36 m-wide trawl track, comprising parallel furrows and sediment piles caused by the trawl doors and shallower grooves from the groundgear, that displaced 1,000 m3 (500 t) sediment and suspended 9.5 t sediment per km of track. The trawl doors had less effect than the rest of the gear in terms of total sediment mass but per m2 the doors had 5× the displacement and 2× the suspension effect, due to their greater penetration and hydrodynamic drag. The suspended sediment spread >1 km away over the following 3–4 days, creating a 5–10 m thick layer of turbid bottom water. Turbidity reached 4.3 NTU (7 mgDW L–1), 550 m from the track, 20 h post-trawling. Particulate Al, Ti, Fe, P, and Mn were correlated with the spatio-temporal pattern of suspension. There was a pulse of dissolved N, P, and Mn to a height of 10 m above the seabed within a few hundred meters of the track, 2 h post-trawling. Dissolved methane concentrations were elevated in the water for at least 20 h. Sediment biogeochemistry in the door track was still perturbed after 48 h, with a decreased oxygen penetration depth and nutrient and oxygen fluxes across the sediment-water interface. These results clearly show the physical effects of bottom trawling, both on seabed topography (on the scale of km and years) and on sediment and particle suspension (on the scale of km and days-weeks). Alterations to biogeochemical processes suggest that, where bottom trawling is frequent, sediment biogeochemistry may not have time to recover between disturbance events and elevated turbidity may persist, even outside the trawled area.
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12. |
- Broman, Elias, et al.
(författare)
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Low Abundance of Methanotrophs in Sediments of Shallow Boreal Coastal Zones With High Water Methane Concentrations
- 2020
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Coastal zones are transitional areas between land and sea where large amounts of organic and inorganic carbon compounds are recycled by microbes. Especially shallow zones near land have been shown to be the main source for oceanic methane (CH4) emissions. Water depth has been predicted as the best explanatory variable, which is related to CH4 ebullition, but exactly how sediment methanotrophs mediates these emissions along water depth is unknown. Here, we investigated the relative abundance and RNA transcripts attributed to methane oxidation proteins of aerobic methanotrophs in the sediment of shallow coastal zones with high CH4 concentrations within a depth gradient from 10–45 m. Field sampling consisted of collecting sediment (top 0–2 cm layer) from eight stations along this depth gradient in the coastal Baltic Sea. The relative abundance and RNA transcripts attributed to the CH4 oxidizing protein (pMMO; particulate methane monooxygenase) of the dominant methanotroph Methylococcales was significantly higher in deeper costal offshore areas (36–45 m water depth) compared to adjacent shallow zones (10–28 m). This was in accordance with the shallow zones having higher CH4 concentrations in the surface water, as well as more CH4 seeps from the sediment. Furthermore, our findings indicate that the low prevalence of Methylococcales and RNA transcripts attributed to pMMO was restrained to the euphotic zone (indicated by Photosynthetically active radiation (PAR) data, photosynthesis proteins, and 18S rRNA data of benthic diatoms). This was also indicated by a positive relationship between water depth and the relative abundance of Methylococcales and pMMO. How these processes are affected by light availability requires further studies. CH4 ebullition potentially bypasses aerobic methanotrophs in shallow coastal areas, reducing CH4 availability and limiting their growth. Such mechanism could help explain their reduced relative abundance and related RNA transcripts for pMMO. These findings can partly explain the difference in CH4 concentrations between shallow and deep coastal areas, and the relationship between CH4 concentrations and water depth.
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13. |
- Choong, Oi Kuan, 1985, et al.
(författare)
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SARS-CoV-2 replicates and displays oncolytic properties in clear cell and papillary renal cell carcinoma
- 2023
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Ingår i: Plos One. - : Public Library of Science (PLoS). - 1932-6203. ; 18:1
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Tidskriftsartikel (refereegranskat)abstract
- The SARS-CoV-2 virus is currently causing a global pandemic. Infection may result in a systemic disease called COVID-19, affecting primarily the respiratory tract. Often the gastrointestinal tract and kidneys also become involved. Angiotensin converting enzyme 2 (ACE2) serves as the receptor for SARS-CoV-2. The membrane proteins, Transmembrane serine protease 2 (TMPRSS2) and Neuropilin 1 (NRP1) are accessory proteins facilitating the virus entry. In this study we show that the human proximal kidney tubules, express these factors. We hypothesized that cancers derived from proximal tubules as clear cell (CCRCC) and papillary renal cell carcinoma (PRCC), retain the expression of the SARS-CoV-2 entry factors making these cancers susceptible to SARS-CoV-2 infection. We used bioinformatics, western blotting, and assessment of tissue micro arrays (TMA) including 263 cases of CCRCC, 139 cases of PRCC and 18 cases of chromophobe RCC to demonstrate that the majority of CCRCC and PRCC cases retained the RNA and protein expression of the entry factors for SARS-CoV-2. We furthermore show that SARS-CoV-2 virus propagated robustly in primary cultures of CCRCC and PRCC cells with a visible virus cytopathogenic effect correlating with viral RNA expression levels. We also noted that the delta-variant of SARS-CoV-2 causes cancer cells to form syncytia in-vitro. This phenomenon was also identified histologically in CCRCC tissue from a patient that had been hospitalized for COVID-19, twelve months prior to nephrectomy. Our data provide insights into SARS-CoV-2 infectivity in renal cell carcinoma and that the virus causes a distinct cytopathogenic effect.
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14. |
- Christenson, Nina, 1975-, et al.
(författare)
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Undervisning för krisberedskap i grundskolans tidigare år – en förstudie
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Omvärldsutvecklingen, Sveriges rustning av det civila försvaret, barnrättsfrågor och att barn är särskilt utsatta i krissituationer är starka skäl till att krisberedskapsundervisning i skolans lägre årskurser bör införas.I denna rapport presenteras en förstudie med syfte att undersöka förutsättningar för undervisning för krisberedskap i skolans lägre årskurser. Rapportens inledande forskningsöversikt visar att krisberedskapsundervisning för barn stärker krismedvetenheten och krishanteringsförmågan i det omgivande samhället och att det är gynnsamt att undervisa om krisberedskap redan i tidig ålder. Undervisning som anammar elevaktiva metoder och samverkar med föräldrar och lokalsamhälle har särskilt positiva effekter på elevers lärande. Resultaten från förstudien visar att svenska kursplaner och läroböcker riktade mot årskurserna ett till sex inte ger någon explicit vägledning för undervisning om krisberedskap. Dock visar kursplane- och läroboksanalysen att befintliga skrivningar och innehållsteman ger öppningar för att inkludera undervisning om krisberedskap inom ramen för flera olika ämnen.Riskerna för att grundläggande samhällsfunktioner störs eller slås ut motiverar att ge plats åt krisberedskapsundervisning i skolan, men det är viktigt att sådan undervisning vilar på en solid grund. Därför avslutas rapporten med en rekommendation om ett kombinerat forsknings- och utvecklingsarbete där yrkesverksamma lärare, forskare och beredskapsexperter tillsammans bidrar med sin expertis i framtagandet av ett undervisningsmaterial för krisberedskap i skolans lägre årskurser.Förstudien tar tagits fram av forskare vid Karlstads universitet knutna till Centrum för forskning om samhällsrisker inom ramen för ett projekt, Krisberedskap i skolan (etapp 1), med Räddningstjänsten Karlstadsregionen som projektledare och Myndigheten för samhällsskydd och beredskap (MSB) som finansiär.
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15. |
- Chuvilin, E., et al.
(författare)
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In-situ temperatures and thermal properties of the East Siberian Arctic shelf sediments : Key input for understanding the dynamics of subsea permafrost
- 2022
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Ingår i: Marine and Petroleum Geology. - : Elsevier BV. - 0264-8172 .- 1873-4073. ; 138
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Tidskriftsartikel (refereegranskat)abstract
- Significant reserves of methane (CH4) are held in the Arctic shelf, but the release of CH4 to the overlying ocean and, subsequently, to the atmosphere has been believed to be restricted by impermeable subsea permafrost, which has sealed the upper sediment layers for thousands of years. Our studies demonstrate progressive degradation of subsea permafrost which controls the scales of CH4 release from the sediment into the water-atmospheric system. Thus, new knowledge about the thermal state of subsea permafrost is crucial for better understanding of the permafrost -hydrate system and associated CH4 release from the East Siberian Arctic Shelf (ESAS) – the broadest and shallowest shelf in the World Ocean, which contains about 80% of subsea permafrost and giant pools of hydrates. Meanwhile, the ESAS, still presents large knowledge gaps in many aspects, especially with respect to subsea permafrost distribution and physical properties of bottom sediments. New field data show that the ESAS has an unfrozen (ice-free) upper sediment layer, which in-situ temperature is −1.0 to −1.8 °C and 0.6оС above the freezing point. On one hand, these cold temperature patterns may be related to the presence of subsea permafrost, which currently primarily occurs in the part of the ESAS that is shallower than 100 m, while ice-bearing sediments may also exist locally under deeper water in the Laptev Sea. On the other hand, the negative bottom sediment temperatures of −1.8 °C measured on the Laptev Sea continental slope sediments underlying water columns as deep as down to 330 m may result from dissociation of gas hydrates or possibly from dense water cascading down from the shelf. In contrast, data collected on recent expeditions in the northern Laptev shelf, zones of warmer bottom temperatures are coinciding with methane seeps, likely induced by seismic and tectonic activity in the area. These warm temperatures are not seen in the East Siberian Sea area, not even in areas of methane seeps, yet with little seismic activity.The thermal conductivity and heat capacity of bottom sediments recorded in the database of thermal parameters for the ESAS areas mainly depend on their lithification degree (density or porosity), moisture content, and particle size distribution. The thermal conductivity and heat capacity average about 1.0 W/(m·K) and 2900 kJ/(m3·K), with ±20% and ±10% variance, respectively, in all sampled Arctic sediments to a sub-bottom interval of 0–0.5 m.
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16. |
- Clement Kinney, J., et al.
(författare)
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On the circulation, water mass distribution, and nutrient concentrations of the western Chukchi Sea
- 2022
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Ingår i: Ocean Science. - : Copernicus GmbH. - 1812-0784 .- 1812-0792. ; 18:1, s. 29-49
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Tidskriftsartikel (refereegranskat)abstract
- Substantial amounts of nutrients and carbon enter the Arctic Ocean from the Pacific Ocean through the Bering Strait, distributed over three main pathways. Water with low salinities and nutrient concentrations takes an eastern route along the Alaskan coast, as Alaskan Coastal Water. A central pathway exhibits intermediate salinity and nutrient concentrations, while the most nutrient-rich water enters the Bering Strait on its western side. Towards the Arctic Ocean, the flow of these water masses is subject to strong topographic steering within the Chukchi Sea with volume transport modulated by the wind field. In this contribution, we use data from several sections crossing Herald Canyon collected in 2008 and 2014 together with numerical modelling to investigate the circulation and transport in the western part of the Chukchi Sea. We find that a substantial fraction of water from the Chukchi Sea enters the East Siberian Sea south of Wrangel Island and circulates in an anticyclonic direction around the island. This water then contributes to the high-nutrient waters of Herald Canyon. The bottom of the canyon has the highest nutrient concentrations, likely as a result of addition from the degradation of organic matter at the sediment surface in the East Siberian Sea. The flux of nutrients (nitrate, phosphate, and silicate) and dissolved inorganic carbon in Bering Summer Water and Winter Water is computed by combining hydrographic and nutrient observations with geostrophic transport referenced to lowered acoustic Doppler current profiler (LADCP) and surface drift data. Even if there are some general similarities between the years, there are differences in both the temperature-salinity and nutrient characteristics. To assess these differences, and also to get a wider temporal and spatial view, numerical modelling results are applied. According to model results, high-frequency variability dominates the flow in Herald Canyon. This leads us to conclude that this region needs to be monitored over a longer time frame to deduce the temporal variability and potential trends. © 2022 Jaclyn Clement Kinney et al.
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17. |
- Cronin, T. M., et al.
(författare)
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Holocene paleoceanography and glacial history of Lincoln Sea, Ryder Glacier, Northern Greenland, based on foraminifera and ostracodes
- 2022
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Ingår i: Marine Micropaleontology. - : Elsevier BV. - 0377-8398 .- 1872-6186. ; 175
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Tidskriftsartikel (refereegranskat)abstract
- We reconstructed Holocene paleoceanography of the Sherard Osborn Fjord (SOF), N Greenland, and Lincoln Sea in the eastern Arctic Ocean using sediment properties and micropaleontology from cores obtained during the Ryder 2019 Expedition. Our aims were to better understand faunal indicators of water mass influence on Ryder Glacier and the Lincoln Sea at water depths >500 m. Benthic microfaunal reflect glacio-marine interval during late deglaciation ~10.5 to 8.5 ka (kiloannum) during the Holocene Thermal Maximum (HTM) with dominant benthic foraminiferal species Cassidulina neoteretis, Cassidulina reniforme, and the ostracode Rabilimis mirabilis. Casssidulina neoteretis is considered an indicator of Atlantic Water (AW) throughout the Arctic Ocean and Nordic Seas; C. reniforme reflects glacio-marine conditions from the retreating Ryder Glacier. Deglaciation was followed by a period of elevated productivity and diverse ostracode faunal assemblages that suggest AW influence from 8.5 to 6 ka in the Lincoln Sea and inside SOF. The Holocene occurrence of the ostracode species Acetabulastoma arcticum, that appears in low numbers in the Lincoln Sea and briefly (~ 4–3 ka) in SOF, reflects the presence of variable sea ice in this region. Based on the similarities of the Lincoln Sea and fjord ostracodes to modern and glacial-deglacial faunas from the central Arctic Ocean, the AW influence likely originates from recirculation of AW water from the central Arctic Basin. In general, our results suggest a strong but temporally varying influence of AW during the entire 10.5 kyr record of the Lincoln Sea and SOF.
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18. |
- Detlef, Henrieka, et al.
(författare)
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Holocene sea-ice dynamics in Petermann Fjord in relation to ice tongue stability and Nares Strait ice arch formation
- 2021
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 15:9, s. 4357-4380
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Tidskriftsartikel (refereegranskat)abstract
- The Petermann 2015 expedition to Petermann Fjord and adjacent Hall Basin recovered a transect of cores, extending from Nares Strait to underneath the 48 km long ice tongue of Petermann glacier, offering a unique opportunity to study ice-ocean-sea ice interactions at the interface of these realms. First results suggest that no ice tongue existed in Petermann Fjord for large parts of the Holocene, raising the question of the role of the ocean and the marine cryosphere in the collapse and re-establishment of the ice tongue. Here we use a multi-proxy approach (sea-ice-related biomarkers, total organic carbon and its carbon isotopic composition, and benthic and planktonic foraminiferal abundances) to explore Holocene sea ice dynamics at OD1507-03TC-41GC-03PC in outer Petermann Fjord. Our results are in line with a tight coupling of the marine and terrestrial cryosphere in this region and, in connection with other regional sea ice reconstructions, give insights into the Holocene evolution of ice arches and associated landfast ice in Nares Strait. The late stages of the regional Holocene Thermal Maximum (6900-5500 cal yr BP) were marked by reduced seasonal sea ice concentrations in Nares Strait and the lack of ice arch formation. This was followed by a transitional period towards Neoglacial cooling from 5500-3500 cal yr BP, where a southern ice arch might have formed, but an early seasonal breakup and late formation likely caused a prolonged open water season and enhanced pelagic productivity in Nares Strait. Between 3500 and 1400 cal yr BP, regional records suggest the formation of a stable northern ice arch only, with a short period from 2500-2100 cal yr BP where a southern ice arch might have formed intermittently in response to atmospheric cooling spikes. A stable southern ice arch, or even double arching, is also inferred for the period after 1400 cal yr BP. Thus, both the inception of a small Petermann ice tongue at similar to 2200 cal yr BP and its rapid expansion at similar to 600 cal yr BP are preceded by a transition towards a southern ice arch regime with landfast ice formation in Nares Strait, suggesting a stabilizing effect of landfast sea ice on Petermann Glacier.
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19. |
- Detlef, Henrieka, et al.
(författare)
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Seasonal sea-ice in the Arctic's last ice area during the Early Holocene
- 2023
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Ingår i: Communications Earth & Environment. - : Springer Science and Business Media LLC. - 2662-4435. ; 4:1
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Tidskriftsartikel (refereegranskat)abstract
- According to climate models, the Lincoln Sea, bordering northern Greenland and Canada, will be the final stronghold of perennial Arctic sea-ice in a warming climate. However, recent observations of prolonged periods of open water raise concerns regarding its long-term stability. Modelling studies suggest a transition from perennial to seasonal sea-ice during the Early Holocene, a period of elevated global temperatures around 10,000 years ago. Here we show marine proxy evidence for the disappearance of perennial sea-ice in the southern Lincoln Sea during the Early Holocene, which suggests a widespread transition to seasonal sea-ice in the Arctic Ocean. Seasonal sea-ice conditions were tightly coupled to regional atmospheric temperatures. In light of anthropogenic warming and Arctic amplification our results suggest an imminent transition to seasonal sea-ice in the southern Lincoln Sea, even if the global temperature rise is kept below a threshold of 2 °C compared to pre-industrial (1850–1900).
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20. |
- Domínguez-Andrés, Jorge, et al.
(författare)
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Evolution of cytokine production capacity in ancient and modern European populations
- 2021
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Ingår i: eLIFE. - : eLife Sciences Publications Ltd. - 2050-084X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- As our ancestors migrated throughout different continents, natural selection increased the presence of alleles advantageous in the new environments. Heritable variations that alter the susceptibility to diseases vary with the historical period, the virulence of the infections, and their geographical spread. In this study we built polygenic scores for heritable traits that influence the genetic adaptation in the production of cytokines and immune-mediated disorders, including infectious, inflammatory, and autoimmune diseases, and applied them to the genomes of several ancient European populations. We observed that the advent of the Neolithic was a turning point for immune-mediated traits in Europeans, favoring those alleles linked with the development of tolerance against intracellular pathogens and promoting inflammatory responses against extracellular microbes. These evolutionary patterns are also associated with an increased presence of traits related to inflammatory and auto-immune diseases.
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21. |
- Dorschel, Boris, et al.
(författare)
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The International Bathymetric Chart of the Southern Ocean Version 2
- 2022
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Ingår i: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 9:1
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Tidskriftsartikel (refereegranskat)abstract
- The Southern Ocean surrounding Antarctica is a region that is key to a range of climatic and oceanographic processes with worldwide effects, and is characterised by high biological productivity and biodiversity. Since 2013, the International Bathymetric Chart of the Southern Ocean (IBCSO) has represented the most comprehensive compilation of bathymetry for the Southern Ocean south of 60 degrees S. Recently, the IBCSO Project has combined its efforts with the Nippon Foundation - GEBCO Seabed 2030 Project supporting the goal of mapping the world's oceans by 2030. New datasets initiated a second version of IBCSO (IBCSO v2). This version extends to 50 degrees S (covering approximately 2.4 times the area of seafloor of the previous version) including the gateways of the Antarctic Circumpolar Current and the Antarctic circumpolar frontal systems. Due to increased (multibeam) data coverage, IBCSO v2 significantly improves the overall representation of the Southern Ocean seafloor and resolves many submarine landforms in more detail. This makes IBCSO v2 the most authoritative seafloor map of the area south of 50 degrees S.
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22. |
- Frigyesi, Attila, et al.
(författare)
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Provsamlingen Swecrit och AI ger ny kunskap vid intensivvård
- 2023
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Ingår i: Lakartidningen. - 0023-7205. ; 120:42, s. 1-5
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The unique Swecrit Biobank and its associated clinical registries for sepsis, ARDS, cardiac arrest, trauma, and COVID-19 include more than 150,000 blood samples and descriptions of critically ill patients. These assets provide a unique opportunity to research and improve the care of the most seriously ill patients through biomarker analyses, proteomic studies, and genetic and epigenetic studies using modern machine learning techniques (artificial intelligence). Interested researchers are invited to submit their proposals and participate.
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23. |
- Garza, Raquel, et al.
(författare)
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Single-cell transcriptomics of human traumatic brain injury reveals activation of endogenous retroviruses in oligodendroglia
- 2023
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Ingår i: Cell Reports. - : Elsevier. - 2211-1247. ; 42:11, s. 113395-
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Tidskriftsartikel (refereegranskat)abstract
- Traumatic brain injury (TBI) is a leading cause of chronic brain impairment and results in a robust, but poorly understood, neuroinflammatory response that contributes to the long-term pathology. We used single-nuclei RNA sequencing (snRNA-seq) to study transcriptomic changes in different cell populations in human brain tissue obtained acutely after severe, life-threatening TBI. This revealed a unique transcriptional response in oligodendrocyte precursors and mature oligodendrocytes, including the activation of a robust innate immune response, indicating an important role for oligodendroglia in the initiation of neuroinflammation. The activation of an innate immune response correlated with transcriptional upregulation of endogenous retroviruses in oligodendroglia. This observation was causally linked in vitro using human glial progenitors, implicating these ancient viral sequences in human neuroinflammation. In summary, this work provides insight into the initiating events of the neuroinflammatory response in TBI, which has therapeutic implications.
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24. |
- Glueder, Anna, et al.
(författare)
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Calibrated relative sea levels constrain isostatic adjustment and ice history in northwest Greenland
- 2022
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 293
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Tidskriftsartikel (refereegranskat)abstract
- Relative Sea Levels (RSLs) derived primarily from marine bivalves near Petermann Glacier, NW Greenland, constrain past regional ice-mass changes through glacial isostatic adjustment (GIA) modeling. Oxygen isotopes measured on bivalves corrected for shell-depth habitat and document changing meltwater input. Rapid RSL fall of up to 62 m/kyr indicates ice loss at or prior to ∼9 ka. Transition to an RSL stillstand starting at ∼6 ka reflects renewed ice-mass loading followed by further mass loss over the past few millennia. GIA simulations of rapid early RSL fall suggest a low regional upper-mantle viscosity. Early loss of grounded ice tracks atmospheric warming and pre-dates the eventual collapse of Petermann Glacier's floating ice tongue near ∼7 ka, suggesting grounding zone stabilization during early phases of deglaciation. We hypothesize mid-Holocene regrowth of regional ice caps in response to cooling and increased precipitation, following loss of the floating shelf ice. Remnants of these ice caps remain present but are now melting.
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25. |
- Haldrup, Jakob, et al.
(författare)
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FRMD6 has tumor suppressor functions in prostate cancer
- 2020
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Ingår i: Oncogene. - : Springer Science and Business Media LLC. - 1476-5594 .- 0950-9232.
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Tidskriftsartikel (refereegranskat)abstract
- Available tools for prostate cancer (PC) prognosis are suboptimal but may be improved by better knowledge about genes driving tumor aggressiveness. Here, we identified FRMD6 (FERM domain-containing protein 6) as an aberrantly hypermethylated and significantly downregulated gene in PC. Low FRMD6 expression was associated with postoperative biochemical recurrence in two large PC patient cohorts. In overexpression and CRISPR/Cas9 knockout experiments in PC cell lines, FRMD6 inhibited viability, proliferation, cell cycle progression, colony formation, 3D spheroid growth, and tumor xenograft growth in mice. Transcriptomic, proteomic, and phospho-proteomic profiling revealed enrichment of Hippo/YAP and c-MYC signaling upon FRMD6 knockout. Connectivity Map analysis and drug repurposing experiments identified pyroxamide as a new potential therapy for FRMD6 deficient PC cells. Finally, we established orthotropic Frmd6 and Pten, or Pten only (control) knockout in the ROSA26 mouse prostate. After 12 weeks, Frmd6/Pten double knockouts presented high-grade prostatic intraepithelial neoplasia (HG-PIN) and hyperproliferation, while Pten single-knockouts developed only regular PIN lesions and displayed lower proliferation. In conclusion, FRMD6 was identified as a novel tumor suppressor gene and prognostic biomarker candidate in PC.
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26. |
- Heide-Jørgensen, Mads Peter, et al.
(författare)
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Evidence of a narwhal (Monodon monoceros) summer ground in Nares Strait
- 2024
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Ingår i: Polar Research. - 0800-0395 .- 1751-8369. ; 43
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Tidskriftsartikel (refereegranskat)abstract
- Our limited knowledge of the marine mammal fauna in northernmost Greenland and Canada, specifically north of 80°N, relies largely on opportunistic observations collected during expeditions with different objectives. The narwhal (Monodon monoceros) migrates long distances in response to ice formation and decay and is notoriously skittish, avoiding areas with ice breakers. Scattered observations from the past 20 years, assessed together with historical observations after 1881, suggest that there is a population of narwhals that uses Hall Basin and its adjacent fjord systems—for example, Nares Strait—as a summer ground. Dating the tusks and bones that have been found shows that narwhals were present in this area as far back as nearly 7000 years ago. The wintering locations of these narwhals remain unknown, highlighting the need to investigate whether they are vulnerable to hunting activities in north-west Greenland. By gaining a better understanding of the narwhals’ winter behaviour and potential hunting risks, we can develop more informed conservation and management strategies for this population.
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27. |
- Herbertsson, Lina, et al.
(författare)
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Bees increase seed set of wild plants while the proportion of arable land has a variable effect on pollination in European agricultural landscapes
- 2021
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Ingår i: Plant Ecology and Evolution. - : Societe Royale de Botanique de Belgique. - 2032-3913 .- 2032-3921. ; 154:3, s. 341-350
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Agricultural intensification and loss of farmland heterogeneity have contributed to population declines of wild bees and other pollinators, which may have caused subsequent declines in insect-pollinated wild plants.Material and methods: Using data from 37 studies on 22 pollinator-dependent wild plant species across Europe, we investigated whether flower visitation and seed set of insect-pollinated plants decline with an increasing proportion of arable land within 1 km.Key results: Seed set increased with increasing flower visitation by bees, most of which were wild bees, but not with increasing flower visitation by other insects. Increasing proportion of arable land had a strongly variable effect on seed set and flower visitation by bees across studies.Conclusion:Factors such as landscape configuration, local habitat quality, and temporally changing resource availability (e.g. due to mass-flowering crops or honey bee hives) could have modified the effect of arable land on pollination. While our results highlight that the persistence of wild bees is crucial to maintain plant diversity, we also show that pollen limitation due to declining bee populations in homogenized agricultural landscapes is not a universal driver causing parallel losses of bees and insect-pollinated plants.
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28. |
- Hogan, Kelly A., et al.
(författare)
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Glacial sedimentation, fluxes and erosion rates associated with ice retreat in Petermann Fjord and Nares Strait, north-west Greenland
- 2020
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Ingår i: The Cryosphere. - : Copernicus GmbH. - 1994-0416 .- 1994-0424. ; 14:1, s. 261-286
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Tidskriftsartikel (refereegranskat)abstract
- Petermann Fjord is a deep ( > 1000 m) fjord that incises the coastline of north-west Greenland and was carved by an expanded Petermann Glacier, one of the six largest outlet glaciers draining the modern Greenland Ice Sheet (GrIS). Between 5 and 70 m of unconsolidated glacigenic material infills in the fjord and adjacent Nares Strait, deposited as the Petermann and Nares Strait ice streams retreated through the area after the Last Glacial Maximum. We have investigated the deglacial deposits using seismic stratigraphic techniques and have correlated our results with high-resolution bathymetric data and core lithofacies. We identify six seismoacoustic facies in more than 3500 line kilometres of subbottom and seismic-reflection profiles throughout the fjord, Hall Basin and Kennedy Channel. Seismo-acoustic facies relate to bedrock or till surfaces (Facies I), subglacial deposition (Facies II), deposition from meltwater plumes and icebergs in quiescent glacimarine conditions (Facies III, IV), deposition at grounded ice margins during stillstands in retreat (grounding-zone wedges; Facies V) and the redeposition of material downslope (Facies IV). These sediment units represent the total volume of glacial sediment delivered to the mapped marine environment during retreat. We calculate a glacial sediment flux for the former Petermann ice stream as 1080-1420 m(3) a(-1) per metre of ice stream width and an average deglacial erosion rate for the basin of 0.29-0.34 mm a(-1). Our deglacial erosion rates are consistent with results from Antarctic Peninsula fjord systems but are several times lower than values for other modern GrIS catchments. This difference is attributed to fact that large volumes of surface water do not access the bed in the Petermann system, and we conclude that glacial erosion is limited to areas overridden by streaming ice in this large outlet glacier setting. Erosion rates are also presented for two phases of ice retreat and confirm that there is significant variation in rates over a glacial-deglacial transition. Our new glacial sediment fluxes and erosion rates show that the Petermann ice stream was approximately as efficient as the palaeo-Jakobshavn Isbra at eroding, transporting and delivering sediment to its margin during early deglaciation.
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29. |
- Holmes, Felicity A., et al.
(författare)
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Calving at Ryder Glacier, Northern Greenland
- 2021
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Ingår i: Journal of Geophysical Research - Earth Surface. - 2169-9003 .- 2169-9011. ; 126:4
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Tidskriftsartikel (refereegranskat)abstract
- Recent evidence has shown increasing mass loss from the Greenland ice sheet, with a general trend of accelerated mass losses extending northwards. However, different glaciers have been shown to respond differently to similar external forcings, constituting a problem for extrapolating and upscaling data. Specifically, whilst some outlet glaciers have accelerated, thinned, and retreated in response to atmospheric and oceanic warming, the behavior of other marine terminating glaciers appears to be less sensitive to climate forcing. Ryder glacier, for which only a few studies have been conducted, is located in North Greenland and terminates with a floating ice tongue in Sherard Osborn Fjord. The persistence or disintegration of floating ice tongues has impacts on glacier dynamics and stability, with ramifications beyond, including sea level rise. This study focuses on understanding the controls on calving and frontal ablation of the Ryder glacier through the use of time-lapse imagery and satellite data. The results suggest that Ryder glacier has behaved independently of climate forcing during recent decades, with fjord geometry exerting a first order control on its calving.
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30. |
- Jakobsson, Lotta, 1967, et al.
(författare)
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ASSESSMENT OF PASSENGER SAFETY IN FUTURE CARS - IDENTIFYING THE REAL-WORLD NEEDS TOWARDS SAFETY SYSTEM DEVELOPMENT
- 2023
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Ingår i: 27th ESV Conference Proceedings.
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Konferensbidrag (refereegranskat)abstract
- Future cars will likely include further collision mitigation systems, seat positions and seating configurations compared to current cars, in addition to an increased degree of shared mobility solutions. At the same time the population is becoming older and the diversity in car passenger dimensions is growing. This calls for assessment tools and evaluation methods beyond the current standardized crash test methods. This paper summarizes the results of a Swedish research project on how to assess the protection of the heterogeneous population of passengers (i.e., nondrivers) in future car crashes, focusing on restraint interaction. With the overall purpose of further improving passenger protection, the specific aims were to achieve method developments based on the enhancement of tools (physical and virtual human substitutes) as well as to create knowledge on passenger protection needs. This comprehensive research project combined multiple competencies and international collaborations, and a large number of studies have been performed using different methods. The applied methods include real-world crash data analyses to identify scenarios and situations, crash testing and simulation, and additionally user-studies conducted in cars to evaluate sitting posture, beltfit, kinematics, comfort, experiences and attitudes. Furthermore, the project included studies on crash test dummies (ATDs) and Human Body Models (HBM). Moreover, adult morphed HBMs were developed in various sizes, ages and sexes, for investigating various protection principles. In novel studies, crash interventions strategies were applied to predicted residual crash configurations. User-studies provided evidence of self-selected passenger postures in real car settings and, thus, deviations from standardized ATD positions. The importance of body shape was highlighted in a beltfit user-study including older adults. Essential booster design parameters were identified for children in upright and reclined seat positions. Restraint principles were investigated for adults in reclined seat positions and with the seat in rearward positions, away from the frontal airbag and knee bolster, along with an evaluation of the capabilities of the assessment tools. The adult HBM morphed to various sizes, ages and sexes were validated for prediction of in-crash kinematics in different impact scenarios, and provided enhanced insights in passenger protection assessment compared to the three standardized sizes of ATDs. Simulations with PIPER6y, a child-sized HBM, emphasized the importance of vehiclebooster-user system interaction. The results from the research project provided input to safety system development, ATD/HBM design, assessment methods development, and a number of identified research challenges for future work. Specifically, there is a need to further explore car passenger interaction with the restraint system in terms of seat positions and variations in body sizes, shapes and postures. The inclusions of the heterogeneous population into more advanced tools such as HBMs are essential, acknowledging that when moving closer to “zero injuries”, the situations to address are more unique and specific. Although a large range of studies using different methods was conducted, many challenges still remain to cover the entire scope of passenger safety in future cars.
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31. |
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32. |
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33. |
- Jakobsson, Martin, et al.
(författare)
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Nyhetsbevakning i samhällskunskap
- 2023
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- I rapporten redovisas resultat från en observationsstudie av nyhetsbevakning i ämnet samhällskunskap i tre högstadielärares klassrum. Vanligtvis sker bevakningen som en egen del i ämnet där man tar del av nyheter och samtalar om dem. Forskning visar att nyhetsbevakning tycks vara en etablerad del i samhällskunskap men få studier har undersökt aktiviteten i detalj. Ett syfte har varit att bidra med kunskap om vad som utmärker nyhetsbevakning mer specifikt. Ett annat syfte har varit att undersöka dess potential att utveckla elevers demokratiska medborgarskap och engagemang om vad som sker i omvärlden. Resultatet visar att nyhetsbevakningen tar cirka en femtedel av undervisningstiden i anspråk och att det sker i början av en lektion isolerat från övrig undervisning. Den genomförs rutinmässigt utan ett uttalat syfte där öppnandet mot omvärlden mest handlar om att etablera en vana att ta del av nyheter och i någon mån verka för allmänbildning. Att närma sig omvärldsfrågor aktivt och demokratiskt uttalas inte även om samtalen om nyheterna innefattar utsagor som implicit öppnar för sådant engagemang. Slutsatsen som dras är att det finns en potential i nyhetsbevakning som kan utvecklas mer så att den i högre grad öppnar för utveckling av ett aktivt medborgarskap.
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34. |
- Jakobsson, Martin, 1966-, et al.
(författare)
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Polar Region Bathymetry : Critical Knowledge for the Prediction of Global Sea Level Rise
- 2022
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Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 8
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Forskningsöversikt (refereegranskat)abstract
- The ocean and the marine parts of the cryosphere interact directly with, and are affected by, the seafloor and its primary properties of depth (bathymetry) and shape (morphology) in many ways. Bottom currents are largely constrained by undersea terrain with consequences for both regional and global heat transport. Deep ocean mixing is controlled by seafloor roughness, and the bathymetry directly influences where marine outlet glaciers are susceptible to the inflow relatively warm subsurface waters - an issue of great importance for ice-sheet discharge, i.e., the loss of mass from calving and undersea melting. Mass loss from glaciers and the Greenland and Antarctic ice sheets, is among the primary drivers of global sea-level rise, together now contributing more to sea-level rise than the thermal expansion of the ocean. Recent research suggests that the upper bounds of predicted sea-level rise by the year 2100 under the scenarios presented in IPCC’s Special Report on the Ocean and Cryosphere in a Changing Climate (SROCCC) likely are conservative because of the many unknowns regarding ice dynamics. In this paper we highlight the poorly mapped seafloor in the Polar regions as a critical knowledge gap that needs to be filled to move marine cryosphere science forward and produce improved understanding of the factors impacting ice-discharge and, with that, improved predictions of, among other things, global sea-level. We analyze the bathymetric data coverage in the Arctic Ocean specifically and use the results to discuss challenges that must be overcome to map the most remotely located areas in the Polar regions in general.
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35. |
- Jakobsson, Martin, et al.
(författare)
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Potential links between Baltic Sea submarine terraces and groundwater seeping
- 2020
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Ingår i: Earth Surface Dynamics. - : Copernicus GmbH. - 2196-6311 .- 2196-632X. ; 8:1, s. 1-15
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Tidskriftsartikel (refereegranskat)abstract
- Submarine groundwater discharge (SGD) influences ocean chemistry, circulation, and the spreading of nutrients and pollutants; it also shapes sea floor morphology. In the Baltic Sea, SGD was linked to the development of terraces and semicircular depressions mapped in an area of the southern Stockholm archipelago, Sweden, in the 1990s. We mapped additional parts of the Stockholm archipelago, areas in Blekinge, southern Sweden, and southern Finland using high-resolution multibeam sonars and sub-bottom profilers to investigate if the sea floor morphological features discovered in the 1990s are widespread and to further address the hypothesis linking their formation to SGD. Sediment coring and sea floor photography conducted with a remotely operated vehicle (ROV) and divers add additional information to the geophysical mapping results. We find that terraces, with general bathymetric expressions of about 1 m and lateral extents of sometimes > 100 m, are widespread in the surveyed areas of the Baltic Sea and are consistently formed in glacial clay. Semicircular depressions, however, are only found in a limited part of a surveyed area east of the island of Asko, southern Stockholm archipelago. While submarine terraces can be produced by several processes, we interpret our results to be in support of the basic hypothesis of terrace formation initially proposed in the 1990s; i.e. groundwater flows through siltier, more permeable layers in glacial clay to discharge at the sea floor, leading to the formation of a sharp terrace when the clay layers above seepage zones are undermined enough to collapse. By linking the terraces to a specific geologic setting, our study further refines the formation hypothesis and thereby forms the foundation for a future assessment of SGD in the Baltic Sea that may use marine geological mapping as a starting point. We propose that SGD through the submarine sea floor terraces is plausible and could be intermittent and linked to periods of higher groundwater levels, implying that to quantify the contribution of freshwater to the Baltic Sea through this potential mechanism, more complex hydrogeological studies are required.
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36. |
- Jakobsson, Martin, et al.
(författare)
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Ryder Glacier in northwest Greenland is shielded from warm Atlantic water by a bathymetric sill
- 2020
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Ingår i: Communications Earth & Environment. - : Springer Science and Business Media LLC. - 2662-4435. ; 1
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Tidskriftsartikel (refereegranskat)abstract
- The processes controlling advance and retreat of outlet glaciers in fjords draining the Greenland Ice Sheet remain poorly known, undermining assessments of their dynamics and associated sea-level rise in a warming climate. Mass loss of the Greenland Ice Sheet has increased six-fold over the last four decades, with discharge and melt from outlet glaciers comprising key components of this loss. Here we acquired oceanographic data and multibeam bathymetry in the previously uncharted Sherard Osborn Fjord in northwest Greenland where Ryder Glacier drains into the Arctic Ocean. Our data show that warmer subsurface water of Atlantic origin enters the fjord, but Ryder Glacier’s floating tongue at its present location is partly protected from the inflow by a bathymetric sill located in the innermost fjord. This reduces under-ice melting of the glacier, providing insight into Ryder Glacier’s dynamics and its vulnerability to inflow of Atlantic warmer water.
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37. |
- Jakobsson, Martin, et al.
(författare)
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Semantiska vågor i undervisningen : Likheter och skillnader i skolämnena matematik och samhällskunskap
- 2023
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Ingår i: Utbildning och lärande. - 1653-0594. ; 17:2, s. 59-78
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Tidskriftsartikel (refereegranskat)abstract
- If students are to build knowledge, it is important to connect disciplinary knowledge to students’ everyday knowledge when teaching. In this study, the relationship between disciplinary- and everyday knowledge in subject-teaching is analysed, based on the semantic dimensions used in Legitimation Code Theory. Un-packing disciplinary concepts through concrete examples implies a shift towards a context-dependent everyday knowledge, while re-packing them entails a shift towards disciplinary abstractions and context-independent generalizations. Over time these shifts constitute so-called semantic waves argued to facilitate students´ knowledge building. Earlier research suggest that the form of these semantic waves can differ between school-subjects. Therefore, this article examines semantic waves in two contrasting subjects – Mathematics and Social Science Education, aiming at a better understanding of how and why semantic waves differ. The results reveal that the forms of semantic waves differ between the two subjects. In Mathematics, when teaching different geometrical concepts, the semantic shifts through un-packing and re-packing were frequent and evenly distributed. When teaching about pricing and household in Social Science, un-packing activities dominated, making shifts biased towards everyday knowledge. These differences are discussed in terms of semantic waves constituting a different pulse when making knowledge-building possible in Mathematics and Social Science.
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38. |
- Jakobsson, Martin, et al.
(författare)
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Teaching about migration on a scientific base : Teachers’ knowledge-building in social studies in Swedish upper elementary school
- 2023
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Ingår i: Acta Didactica Norden. - : Universitetet i Oslo. - 2535-8219. ; 17:3
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Tidskriftsartikel (refereegranskat)abstract
- This article examines two conversations in a study-circle on migration. The conversations are part of the first phase of a subject didactic project between social studies teachers at upper elementary school and researchers at a university in Sweden. In the conversations, which are moderated by two researchers, the teachers are expected to build their own knowledge about migration and how teaching about migration can be carried out. Previous research on social studies teaching in the earlier school years has shown that the connection to substantive scientific knowledge is weak. Through deeper theoretical knowledge and an increased didactic repertoire, teachers can in turn give students access to specialised knowledge, i.e. knowledge that helps them deal with society's major issues. The article aims to investigate how the teachers' knowledge building can be made visible and understood, as well as what function the researchers fulfill in the conversations. Both conversations have been analyzed semantically with tools from Legitimation Code Theory. Through the analysis, we follow how scientific substantive knowledge about migration is transformed and linked to teachers' experiences and more general everyday understanding of the phenomenon. The analysis shows that there is a connection between an everyday understanding and a scientific understanding in the part of the conversation where the teachers build their own knowledge about migration, but that it is more difficult to achieve a connection between scientific knowledge and developing the teaching content. Here, a focus on the content, on what should be taught and why, seems to make it easier for teachers to make connections to specialized knowledge, while a focus on how-to questions and who should be taught does not do so to the same extent.
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39. |
- Jakobsson, Martin, et al.
(författare)
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The International Bathymetric Chart of the Arctic Ocean Version 4.0
- 2020
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Ingår i: Scientific Data. - : Springer Science and Business Media LLC. - 2052-4463. ; 7:1
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Tidskriftsartikel (refereegranskat)abstract
- Bathymetry (seafloor depth), is a critical parameter providing the geospatial context for a multitude of marine scientific studies. Since 1997, the International Bathymetric Chart of the Arctic Ocean (IBCAO) has been the authoritative source of bathymetry for the Arctic Ocean. IBCAO has merged its efforts with the Nippon Foundation-GEBCO-Seabed 2030 Project, with the goal of mapping all of the oceans by 2030. Here we present the latest version (IBCAO Ver. 4.0), with more than twice the resolution (200 x 200m versus 500 x 500m) and with individual depth soundings constraining three times more area of the Arctic Ocean (similar to 19.8% versus 6.7%), than the previous IBCAO Ver. 3.0 released in 2012. Modern multibeam bathymetry comprises similar to 14.3% in Ver. 4.0 compared to similar to 5.4% in Ver. 3.0. Thus, the new IBCAO Ver. 4.0 has substantially more seafloor morphological information that offers new insights into a range of submarine features and processes; for example, the improved portrayal of Greenland fjords better serves predictive modelling of the fate of the Greenland Ice Sheet. Machine-accessible metadata file describing the reported data: 10.6084/m9.figshare.12369314
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40. |
- Jakobsson, Rasmus, 1987, et al.
(författare)
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Family History and Risk of Renal Cell Carcinoma: A National Multiregister Case-Control Study
- 2024
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Ingår i: The Journal of urology. - 1527-3792. ; 211:1, s. 71-79
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: Our purpose was to investigate the association between family history of renal cell carcinoma (RCC) and RCC risk. MATERIALS AND METHODS: RCC cases diagnosed in Sweden between 2005 and 2014 and 10 matched controls were identified using the Renal Cell Cancer Database Sweden, with linkage to the Multigeneration Register and the Swedish Cancer Registry. The association between a family history of RCC and RCC was investigated, overall and by sex and age groups. RESULTS: Among 9416 RCC cases, 294 (3.1%) had 1 or more parent or sibling (first-degree relative [FDR]) with RCC. Median age at diagnosis for cases with an affected FDR was 65 years (IQR 59-71) and 68 years (IQR 60-75) for all cases. The proportion of women was significantly higher among familial RCC compared to sporadic RCC (44.6% vs 38.5%, P = .035). RCC was twice as likely with 1 or more FDR with RCC (OR 1.9; CI 1.65-2.16). Stratified analysis showed an OR of 2.4 for women (CI 1.93-2.92) and 1.6 for men (CI 1.35-1.93). Two or more FDRs was associated with a sixfold increased risk (95% CI 2.37-15.5). Familial RCC was strongly associated with bilateral and multifocal tumors (OR 5.5; CI 2.36-13.0, OR 3.5; CI 1.89-6.49). CONCLUSIONS: In this Swedish data set, 3.1% of RCC patients have 1 or more FDR diagnosed with RCC. There was no statistical difference in median age between sporadic RCC and familial RCC. Having 1 or more FDR with RCC approximately doubles the risk of RCC with a higher risk increase for women than for men. People with 2 FDRs with RCC constitute a small high-risk group that may benefit from screening.
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41. |
- Jennings, Anne, et al.
(författare)
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Modern and early Holocene ice shelf sediment facies from Petermann Fjord and northern Nares Strait, northwest Greenland
- 2022
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 283
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Tidskriftsartikel (refereegranskat)abstract
- Based on sediment cores and geophysical data collected from Petermann Fjord and northern Nares Strait, NW Greenland, an Arctic ice shelf sediment facies is presented that distinguishes sub and pro ice shelf environments. Sediment cores were collected from sites beneath the present day Petermann Ice Tongue (PIT) and in deglacial sediments of northern Nares Strait with a focus on understanding the glacial and oceanographic history over the last 11,000 cal yr BP. The modern sub ice shelf sediment facies in Petermann Fjord is laminated and devoid of coarse clasts (IRD) due to strong basal melting that releases debris (debris filtering) from the basal ice at the grounding zone driven by buoyant subglacial meltwater and entrained Atlantic Water. Laminated sediments in the deep basin proximal to the gounding zone comprise layers of fine mud formed by suspension settling from turbid meltwater plumes (plumites) interrupted by normally graded very fine sand to medium silt layers with sharp basal contacts and rip-up clasts of mud, interpreted as turbidites. An inner fjord sill limits distribution of sediment gravity flows from the grounding zone to the deep inner fjord basin, such that sites on the inner sill and beyond the ice tongue largely only comprise plumites. Bioturbation and foraminiferal abundances increase with distance from the grounding zone. The benthic foraminiferal species, Elphidium clavatum is absent beneath the ice tongue, but dominant in the turbid meltwater influenced environment beyond the ice tongue. The very sparse IRD in sediments beneath the PIT and in the fjord beyond the PIT derives mainly from englacial debris in the ice tongue, side valley glaciers, rock falls from the steep fjord walls and sea ice.We use the modern ice shelf sediment facies characteristics to infer the past presence of ice shelves in northern Nares Strait using analyses of sediment cores from several cruises (OD1507, HLY03, 2001LSSL, RYDER19). On bathymetric highs, bioturbated mud with dispersed IRD overlies a 10–15 m thick, distinctly laminated silt and clay unit with rare coarse clasts and sparse foraminifera which forms a sediment drape of nearly uniform thickness. We interpret these laminated sediments to represent glaciomarine deposition by meltwater plumes emanating from ice streams that terminated in floating ice shelves. IRD layers, shifts in sediment composition (qXRD, MS and XRF) and faunal assemblage changes in the laminated unit document periods of ice-shelf instability sometimes, but not always, coupled with grounding zone retreat. Our deglacial reconstruction, including ice shelves, begins ∼10.7 cal ka BP, with confluent ice streams grounded in Hall Basin fronted by the Robeson Channel ice shelf. Ice shelf breakup and grounding zone retreat to relatively stable grounding zones at Kennedy Channel and the mouth of Petermann Fjord was accomplished by 9.4 cal ka BP when the Hall Basin ice shelf was established. This ice shelf broke up and reformed once prior to the final break up at 8.5 to 8.4 cal ka BP marking ice stream collapse, separation of Greenland and Innuitian ice sheets, and the opening of Nares Strait for Arctic-Atlantic throughflow. The Petermann ice shelf remained in Hall Basin until the Petermann Glacier retreated from the fjord mouth ∼7.1 cal ka BP. The resilience of these northern ice streams to strong early Holocene insolation and subsurface Atlantic Water advection is attributed to their northern aspect, buttressing by narrow passages, and high ice flux from the Greenland Ice Sheet (GIS).
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42. |
- Jennings, Anne, et al.
(författare)
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Modern foraminiferal assemblages in northern Nares Strait, Petermann Fjord, and beneath Petermann ice tongue, NW Greenland
- 2020
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Ingår i: Arctic, Antarctic and Alpine research. - : Informa UK Limited. - 1523-0430 .- 1938-4246. ; 52:1, s. 491-511
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Tidskriftsartikel (refereegranskat)abstract
- Calving events of Petermann Glacier, northwest Greenland, in 2010 and 2012 reduced the length of its ice tongue by c. 25 km, allowing exploration of newly uncovered seafloor during the Petermann 2015 Expedition. This article presents the results of foraminiferal analysis and environmental data from thirteen surface sediment samples in northern Nares Strait and Petermann Fjord, including beneath the modern ice tongue. This is the first study of living foraminifera beneath an arctic ice tongue and the first modern foraminiferal data from this area. Modern assemblages were studied to constrain species environmental preferences and to improve paleoenvironmental interpretations of foraminiferal assemblages. Sub-ice tongue assemblages differed greatly from those at all other sites, with very low faunal abundances and being dominated by agglutinated fauna, likely reflecting low food supply under the ice tongue. Fjord fauna were comprised of 80 percent or more calcareous species. Notably,Elphidium clavatumis absent beneath the ice tongue although it is dominant in the fjord. Increasing primary productivity associated with the transition to mobile sea ice, diminishing influence of the Petermann Glacier meltwater with distance from the grounding line, and increased influence of south-flowing currents in Nares Strait are the important controls on the faunal assemblages.
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43. |
- Ketzer, João Marcelo, et al.
(författare)
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Discovery of a major seafloor methane release site in Europe : The Landsort deep, Baltic Sea.
- 2024
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Ingår i: EGU General Assembly 2024. - : European Geosciences Union (EGU).
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Konferensbidrag (refereegranskat)abstract
- A recently acquired multidisciplinary dataset comprising acoustic surveys (high-resolution sub- bottom profiles, multi-beam bathymetry, and broad band mid-water echo sounder), geochemistry (gas chemical and isotopic composition, porewater chemistry), and sedimentology (core lithology and X-ray CT) in the area of the Landsort deep (450 m of depth), south of Stockholm Archipelago, revealed the existence of an extensive (20 km2) region of the seafloor where massive gas release is occurring in the form of multiple bubble streams. This new discovery represents a major seafloor methane release site in Europe and is comparable in area to other large sites worldwide such as the ones in Svalbard and in the South Atlantic Ocean associated with gas hydrate provinces. The gas is formed mostly by methane of microbial origin. Surprisingly, bubbles rise 100’s of meters above the seafloor and reach surface waters above the halocline/oxycline at around 80 m of depth. Some bubbles appear to reach the sea-air interface and their potential methane contribution to the atmosphere is under investigation. Another surprising observation is the absence of major seafloor features like pockmarks in the gas release area. The reasons for the seafloor methane release in the Landsort deep are still not entirely clear, but our preliminary acoustic and sedimentological data suggest that bottom currents may have acted to facilitate the accumulation of organic-rich sediments in a thick drift deposit during the Holocene and the modern warm period (latest 100 years). Our data further suggest that the high sedimentation rate in the drift deposit continuously supplies fresh organic matter that is quickly buried below a thin sulphate reduction zone, fueling vigorous methanogenesis and abundant methane formation. Similar methane release sites might be discovered in other known large drift deposits in the Baltic Sea.
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44. |
- Martens, Jannik, et al.
(författare)
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Remobilization of dormant carbon from Siberian-Arctic permafrost during three past warming events
- 2020
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Ingår i: Science Advances. - : American Association for the Advancement of Science (AAAS). - 2375-2548. ; 6:42
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Tidskriftsartikel (refereegranskat)abstract
- Carbon cycle models suggest that past warming events in the Arctic may have caused large-scale permafrost thaw and carbon remobilization, thus affecting atmospheric CO2 levels. However, observational records are sparse, preventing spatially extensive and time-continuous reconstructions of permafrost carbon release during the late Pleistocene and early Holocene. Using carbon isotopes and biomarkers, we demonstrate that the three most recent warming events recorded in Greenland ice cores-(i) Dansgaard-Oeschger event 3 (similar to 28 ka B.P.), (ii) Bolling-Allerod (14.7 to 12.9 ka B.P.), and (iii) early Holocene (similar to 11.7 ka B.P.)-caused massive remobilization and carbon degradation from permafrost across northeast Siberia. This amplified permafrost carbon release by one order of magnitude, particularly during the last deglaciation when global sea-level rise caused rapid flooding of the land area thereafter constituting the vast East Siberian Arctic Shelf. Demonstration of past warming-induced release of permafrost carbon provides a benchmark for the sensitivity of these large carbon pools to changing climate.
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45. |
- Muchowski, Julia C., 1989-
(författare)
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Uncovering Ocean Mixing near Rough Bathymetry : Using Broadband Acoustics
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Ocean mixing related to rough bathymetry is highly dynamic and exhibits large spatial and temporal variability. Therefore, established in-situ methods as well as numerical models often lack the resolution to capture this type of mixing. In this thesis, acoustics are used to observe, map and quantify stratified mixing at unprecedented resolution. Acoustic broadband data from a Simrad EK80 and co-located microstructure data from a Sea & Sun Technology MicroStructure profiler (MSS) were collected during two cruises on R/V Electra in Feb-March 2019 and 2020 in the Southern Quark region in the northern Åland Sea, Baltic Sea. In the first manuscript (M1), an existing acoustic model to quantify turbulent mixing from acoustic backscatter is revisited and applied to the co-located data sets. Possibilities and limitations of applying the acoustic model are investigated in detail. In a following case study (M2), the acoustic model is applied to a subset of the data where rough bathymetry reaches into stratified flow and highly increases mixing across the halocline. The dominant mixing mechanism is revealed to be wake vortices and their impact is estimated using a diffusion model. The final case study (M3) emphasizes the impact of mixing in the Southern Quark on exchange processes between the distinctly different Northern Baltic Proper and the Bothnian Sea. The acoustic observations uncover the detailed structure (M1-M3) and temporal development (M3) of turbulent diapycnal mixing in heterogeneous flow over rough bathymetry. This thesis is a step towards increased applicability and automatized analysis of acoustic broadband data for identifying and quantifying turbulent diapycnal mixing.
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46. |
- Muchowski, Julia, 1989-, et al.
(författare)
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Diapycnal Mixing Induced by Rough Small-Scale Bathymetry
- 2024
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Diapycnal mixing in the oceans is crucial for local ecosystems as well as the large-scale circulation because it impacts vertical transport rates of heat, salt, oxygen, and other dissolved substances. We investigate the effect of extremely rough bathymetry on mixing and energy dissipation in a coastal region characterized by small-scale seafloor features penetrating a strongly-stratified density interface. While most studies of this type focus on tidal flow, we present shear microstructure measurements and co-located acoustic observations from the non-tidal Baltic Sea. Acoustic observations indicate temperature and salinity microstructure variance and therefore regions of diapycnal mixing. Due to their high resolution, acoustics enable us to resolve the variability and intermittency of stratified turbulence in the vicinity of the obstacles. Scale analysis and acoustic imaging suggest that the underlying mixing mechanisms are topographic wake eddies and, to a smaller extent, breaking internal waves. Depth averaged dissipation rates (1.1∙10-7W kg-1) and turbulent vertical diffusivities (7∙10-4m2s-1) in the halocline exceed those at a nearby reference station with smooth bathymetry by up to two orders of magnitude. Our study emphasizes the importance of rough small-scale (<1km) bathymetric features for energy dissipation and vertical transport of e.g. salt, heat and oxygen in coastal areas.
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47. |
- Muchowski, Julia, 1989-, et al.
(författare)
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Diapycnal Mixing Induced by Rough Small-Scale Bathymetry
- 2023
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 50:13
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Tidskriftsartikel (refereegranskat)abstract
- Diapycnal mixing impacts vertical transport rates of salt, heat, and other dissolved substances, essential for the overturning circulation and ecosystem functioning in marine systems. While most studies have focused on mixing induced by individual obstacles in tidal flows, we investigate the net effect of non-tidal flow over multiple small-scale (<1 km) bathymetric features penetrating a strongly-stratified density interface in a coastal region. We combine high-resolution broadband acoustic observations of turbulence microstructure with traditional shear microstructure profiling, to resolve the variability and intermittency of stratified turbulence related to the rough bathymetry. Scale analysis and acoustic imaging suggest that underlying mixing mechanisms are related to topographic wake eddies and breaking internal waves. Depth averaged dissipation rates (1.1 × 10−7 Wkg−1) and turbulent vertical diffusivities (7 × 10−4 m2s−1) in the halocline exceed reference values by two orders of magnitude. Our study emphasizes the importance of rough small-scale bathymetric features for the vertical transport of salt in coastal areas.
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48. |
- Nikiforov, Sergey, et al.
(författare)
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The Extent of Glaciation in the Pechora Sea, Eurasian Arctic, Based on Submarine Glacial Landforms
- 2023
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Ingår i: Geosciences. - : MDPI AG. - 2076-3263. ; 13:2
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Tidskriftsartikel (refereegranskat)abstract
- The Pechora Sea is optimally located for studying the coalescence of a glacial and periglacial continental shelf zone in the high Arctic. Here, we present data acquired during cruises of the RV Akademik Nikolaj Strakhov in 2018–2021, revealing the distribution of submarine glacial landforms in the central part of the Pechora shelf area. Based on moraines and the distribution of glacial lineations, the extent of the ice sheet during the Last Glacial Maximum (LGM) is proposed. The crests of the moraine ridges and the slopes of their sides express a variation in morphology, and the ridges combine into irregular complexes. The moraines are primarily composed of coarse cobble-sized material with an addition of coarse sand and other sedimentary fractions. The mapped glacial landforms clearly indicate that an ice sheet extended over the area, while the Pechora basin, at the same time, was comprised of lowland characterized by a cryogenic subaerial landscape. Based on the result from this study, the extent and ice-flow pattern of the Barents-Kara Ice Sheet during the LGM were determined.
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49. |
- Nilsson, Johan, 1965-, et al.
(författare)
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Hydraulic suppression of basal glacier melt in sill fjords
- 2023
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Ingår i: The Cryosphere. - 1994-0416 .- 1994-0424. ; 17:6, s. 2455-2476
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Tidskriftsartikel (refereegranskat)abstract
- Using a conceptual model, we examine how hydraulically controlled exchange flows in silled fjords affect the relationship between the basal glacier melt and the features of warm intermediate Atlantic Water (AW) outside the fjords. We show that an exchange flow can be forced to transit into the hydraulic regime if the AW interface height decreases, the AW temperature increases, or the production of glacially modified water is boosted by subglacial discharge. In the hydraulic regime, the heat transport across the sill becomes a rate-limiting factor for the basal melt, which is suppressed. An interplay between processes near the ice-ocean boundary and the hydraulically controlled exchange flow determines the melt dynamics, and the sensitivity of the basal melt to changes in the AW temperature is reduced. The model results are discussed in relation to observations from the Petermann, Ryder, and 79∘ N glaciers in northern Greenland.
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50. |
- Nordgren, Kenneth, 1962-, et al.
(författare)
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Collegial Planning and Preparation as Subject-didactical School Improvement
- 2023
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Konferensbidrag (refereegranskat)abstract
- Planning and preparation (PaP) are vital for high-quality teaching and thus for student learning. Nevertheless, the infrastructure to support teachers' PaP is often poorly developed. This project brings together the fields of subject didactic and school development in order to investigate PaP as part of an organised infrastructure and as qualified activity. We focus how infrastructure can be organised to support PaP in sustainable ways for professional development, efficient for transforming knowledge into relevant teaching activities, and is systematic and dialogic in its formative approach. The aim is to develop knowledge about a didactical collegial practice as well as about its role in the local school infrastructure. Our research-based hypothesis is that teachers PaP benefit from a collegial collaboration (Darling-Hammond et al., 2017) and that the implementation of such a designated work needs the local school management's active support (Jarl et al., 2017). We have followed the commencement and implementation of twelve subject-based planning teams (audio recorded meetings; documents). A modified version of the Tyler-model (Tyler, 1950), and tools from legitimation code theory (Maton, 2014) frames the analysis. The contribution to the fields of subject didactics bridge the knowledge gap about PaP qualities and competencies. It is likewise important for school improvement, as there is a parallel gap about leading PaP as a strategy for improvement. This knowledge is vital for improving school-reform programs, and teacher education.
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