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- Baykal, Yunus, et al.
(författare)
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Eurasian Ice Sheet derived meltwater pulses and their role in driving atmospheric dust activity: Late Quaternary loess sources in SE England
- 2022
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Ingår i: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 296, s. 107804-107804
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Tidskriftsartikel (refereegranskat)abstract
- The role of Quaternary ice sheet fluctuations in driving meltwater pulses and ocean circulation perturbations is widely acknowledged. What is less clear is the role of these processes in driving changes in past atmospheric dust activity, and possible wider links between dust and climate. Terrestrial windblown dust (loess) deposits along the northern fringe of the European loess belt potentially record past atmospheric dust emission from regions close to the former Eurasian Ice Sheet (EIS) and provide a means to evaluate the role of ice sheet fluctuations in the past dust cycle. Numerical loess chronologies across this region generally agree on greatly enhanced dust deposition rates during MIS 2, when the EIS reached its maximum extent. Yet, uncertainties over the sources of this material prevent understanding of the precise causes of this greatly enhanced atmospheric dustiness, and any potential link to ice sheet fluctuations and climate. In southeast England, loess accumulation dominantly occurred in two phases centered on 25–23.5 ka and 20–19 ka, matching the timing of coalescence of the Fennoscandian and British-Irish ice sheets and specifically advances and retreats of nearby ice lobes in the western North Sea. As such, these deposits provide an ideal test of the role of ice sheet fluctuations in atmospheric dust dynamics. Here we undertake such a test through a detailed provenance study of loess in southeast England and potential dust source sediments across the North Sea region. We group extensive new and published data sets of detrital zircon U–Pb ages from basement rocks and Cenozoic sediments in the North Sea area, which not only provide new insight into both loess source, but also the nature of sediment transport over NW Europe into the North Sea basin more widely. Multi-proxy evidence allows us to unambiguously identify ice sheet derived sediments in the exposed North Sea basin as the dominant source of loess in southeast England, while fluvial sediments delivered by rivers draining Continental Europe possibly contributed additional source material to the first loess accumulation phase. We propose that sudden retreats of the North Sea Lobe released substantial amounts of sediment rich meltwater into the southern North Sea and Channel basins, driving accelerated dust emission, loess deposition and provenance variability in NW Europe during MIS 2. Moreover, we propose that this model of dust activity driven by proglacial sediment availability may be applicable for EIS marginal regions more widely, even where resultant loess cover is rarely preserved due to extensive erosion and reworking along the ice marginal spillway. This implies the role of ice sheets in controlling wider dust emission may be underestimated. In addition to driving changes in ocean circulation through meltwater pulses, ice sheet dynamics in the Quaternary may have also driven substantial and abrupt changes in atmospheric dust activity. This mechanism may in part explain the coupling between dust and climate events widely seen in Quaternary dust sediment records and suggests a possible major role of high latitude dust emission in MIS 2 dustiness across Europe and beyond.
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| 2. |
- Bignert, Anders, et al.
(författare)
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Comments Concerning the National Swedish Contaminant Monitoring Programme in Marine Biota, 2008
- 2008
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- This report gives a summary of the monitoring activities within the national Swedish contaminant programme in marine biota. It is the result from the joint efforts of: the Department of Applied Environmental Science at Stockholm University (analyses of organochlorines), the Department of Environmental Assessment at Swedish University of Agricultural Sciences (analyses of heavy metals), Department of Chemistry at Umeå University (analyses of PCDD/PCDF) and the Department of Contaminant Research at the Swedish Museum of Natural History (co-ordination, sample collection administration, sample preparation, recording of biological variables, storage of frozen biological tissues in the Environmental Specimen Bank for retrospective studies, data preparation and statistical evaluation). The monitoring programme is financiated by the Environmental Protection Agency (EPA) in Sweden.The data of concern in this report represent the bioavailable part of the investigated contaminants i.e. the part that has virtually passed through the biological membranes and may cause toxic effects. The objectives of the monitoring program in marine biota could be summarised as follows:• to estimate the levels and the normal variation of various contaminants in marine biota from several representative sites, uninfluenced by local sources, along the Swedish coasts. The goal is to describe the general contaminant load and to supply reference values for regional and local monitoring programmes• to monitor long term time trends and to estimate the rate of found changes.quantified objective: to detect an annual change of 10% within a time period of 10 years with a power of 80% at a significance level of 5%.• to estimate the response in marine biota of measures taken to reduce the discharges of various contaminantsquantified objective: to detect a 50% decrease within a time period of 10 years with a power of 80% at a significance level of 5%.• to detect incidents of regional influence or widespread incidents of ‘Chernobyl’- character and to act as watchdog monitoring to detect renewed usage of banned contaminants.quantified objective: to detect an increase of 200% a single year with a power of 80% at a significance level of 5%.• to indicate large scale spatial differencesquantified objective: to detect differences of a factor 2 between sites with a power of 80% at a significance level of 5%.• to explore the development and regional differences of the composition and pattern of e.g. PCB’s, HCH’s and DDT’s as well as the ratios between various contaminants.• the time series are also relevant for human consumption since important commercial fish species like herring and cod are sampled. A co-operation with the Swedish Food Administration is established. Sampling is also co-ordinated with SSI (Swedish Radiation Protection Authority) for analysing radionuclides in fish and blue mussels (HELCOM, 1992).• all analysed, and a large number of additional specimens, of the annually systematically collected material are stored frozen in the Environmental Specimen Bank.. This invaluable4material enables future retrospective studies of contaminants impossible to analyse today as well as control analyses of suspected analytical errors.• although the programme is focused on contaminant concentration in biota, also the development of biological variables like e.g. condition factor (CF), liver somatic index (LSI) and fat content are monitored at all sites. At a few sites, integrated monitoring with fish physiology and population are running in co-operation with the University of Gothenburg and the Swedish Board of Fisheries.• experiences from the national programme with several time series of over 25 years can be used in the design of regional and local monitoring programmes.• the perfectly unique material of high quality and long time series is further used to explore relationships among biological variables and contaminant concentrations in various tissues; the effects of changes in sampling strategy, the estimates of variance components and the influence on the concept of power etc.• the accessibility of high quality data collected and analysed in a consistent manner is an indispensable prerequisite to evaluate the validity of hypothesis and models concerning the fate and distribution of various contaminants. It could furthermore be used as input of ‘real’ data in the ongoing model building activities concerning marine ecosystems in general and in the Baltic and North Sea environment in particular.• the contaminant programme in marine biota constitute an integrated part of the national monitoring activities in the marine environment as well as of the international programmes within ICES, OSPARCOM and HELCOM.The present report displays the timeseries of analysed contaminants in biota and summarises the results from the statistical treatment. It does not in general give the background or explanations to significant changes found in the timeseries. Increasing concentrations thus, urge for intensified studies.Short comments are given for temporal trends as well as for spatial variation and, for some contaminants, differences in geometric mean concentration between various species caught at the same site. Sometimes notes of seasonal variation and differences in concentration between tissues in the same species are given. This information could say something about the relative appropriateness of the sampled matrix and be of help in designing monitoring programmes. In the temporal trend part, an extract of the relevant findings is summarised in the 'conclusion'-paragraph. It should be stressed though, that geographical differences may not reflect antropogenic influence but may be due to factors like productivity, temperature, salinity etc.The report is continuously updated. The date of the latest update is reported at the beginning of each chapter. The creation date of each figure is written in the lower left corner.
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| 5. |
- Tarish, Firas L., et al.
(författare)
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Castration radiosensitizes prostate cancer tissue by impairing DNA double-strand break repair
- 2015
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Ingår i: Science Translational Medicine. - : American Association for the Advancement of Science (AAAS). - 1946-6234 .- 1946-6242. ; 7:312
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Tidskriftsartikel (refereegranskat)abstract
- Chemical castration improves responses to radiotherapy in prostate cancer, but the mechanism is unknown. We hypothesized that this radiosensitization is caused by castration-mediated down-regulation of non-homologous end joining (NHEJ) repair of DNA double-strand breaks (DSBs). To test this, we enrolled 48 patients with localized prostate cancer in two arms of the study: either radiotherapy first or radiotherapy after neoadjuvant castration treatment. We biopsied patients at diagnosis and before and after castration and radiotherapy treatments to monitor androgen receptor, NHEJ, and DSB repair in verified cancer tissue. We show that patients receiving neoadjuvant castration treatment before radiotherapy had reduced amounts of the NHEJ protein Ku70, impaired radiotherapy-induced NHEJ activity, and higher amounts of unrepaired DSBs, measured by gamma-H2AX foci in cancer tissues. This study demonstrates that chemical castration impairs NHEJ activity in prostate cancer tissue, explaining the improved response of patients with prostate cancer to radiotherapy after chemical castration.
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| 6. |
- Ali, Sharafat, Associate Professor, 1976-, et al.
(författare)
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Effect of composition on the thermal properties and structure of M-Al-Si-O-N glasses, M = Na, Mg, Ca
- 2024
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Ingår i: Progress in Solid State Chemistry. - : Elsevier. - 0079-6786 .- 1873-1643. ; 74
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Forskningsöversikt (refereegranskat)abstract
- The primary objective of this study is to explore the relationship between the composition, structure, and thermal characteristics of M-Al-Si-O-N glasses, with M representing sodium (Na), magnesium (Mg), or calcium (Ca). The glasses were prepared by melting in a quartz crucible at 1650 degrees C and AlN precursor (powder) was utilized as a nitrogen source. The measured thermal properties studied were glass transition temperature (Tg), crystallization temperature (Tc), glass stability, viscosity, and thermal expansion coefficient (alpha). The findings indicate that increasing the aluminum content leads to higher glass transition, crystallization temperatures, and viscosities. In contrast, fragility values increase with the Al contents, while modifier elements and silicon content influence thermal expansion coefficient values. FTIR analysis revealed that in all glasses, the dominant IR bands are attributed to the presence of Q2 and Q3 silicate units. The effect of Al is observed as a progressive polymerization of the silicate network resulting from the glass-forming role of Al2O3. In most samples, the Q4 silicate mode was also observed, strongly related to the high Al content. Overall, the study shows that the complexity of composition-property correlations where the structural changes affect the properties of Mg/Ca-based oxynitride glasses has potential implications for their use in various technological fields.
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| 7. |
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| 8. |
- Kvarnlöf, Linda, 1982-
(författare)
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Landsbygder i brand : Kroniska kriser och krishantering på periferialiserade platser
- 2022
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Ingår i: Kulturella perspektiv - Svensk etnologisk tidskrift. - : Foreningen Kulturella Perspektiv. - 1102-7908 .- 2004-0288. ; 31, s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Artikelns syfte är att undersöka hur en akut kris, i det här fallet skogsbränderna sommaren 2018, förstås mot bakgrund av en bredare social och politisk kontext, nämligen den kroniska kris som en periferialisering av landsbygden utgör. Här studeras en sådan periferialisering framförallt genom hur den tar sig i uttryck i människors berättelser om och erfarenheter från skogsbränderna sommaren 2018. Artikeln grundar sig på intervjuer med räddningspersonal, frivilliga och evakuerade från några av de byar som hotades av skogsbränderna. I dessa intervjuer ryms både motstånd och försvar: ett motstånd mot, och ett ifrågasättande av, landsbygders ojämlika förutsättningar till krishantering och samtidigt ett försvar av den egna bygden och de politiska förutsättningar som råder där.
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| 9. |
- Sereda, Elvira, et al.
(författare)
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Addition of crop residues affects a detritus-based food chain depending on litter type and farming system
- 2015
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Ingår i: Basic and Applied Ecology. - : Elsevier BV. - 1618-0089 .- 1439-1791. ; 16:8, s. 746-754
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Tidskriftsartikel (refereegranskat)abstract
- The addition of crop residues is a common farming practice to increase the organic carbon content of agricultural soils with particular importance in organically managed crops. Residues can be added either from the crop plant itself or from other plants and the type of litter may differentially affect decomposer populations. Effects of litter addition may cascade up to affect generalist predators via trophic cascades or modifications of structural microhabitat properties with unknown consequences for the role of these predators in below- and aboveground food webs. Wheat and maize litter were added to organically and conventionally managed wheat fields and effects on generalist predator and Collembola numbers, litter decomposition and carbon utilization as estimated by stable isotope analysis were studied, Significantly more predators were sampled in plots with maize litter compared to plots with wheal litter and under organic farming. Collembola numbers were not significantly affected by litter type or farming system.. Litter mass loss was highest in plots that received wheat litter under organic management and was negatively related to predator, but not Collemhola numbers. :Individuals of Lepidocyrtus spp. (Collembola) incorporated high percentages of maize-borne carbon compared to predator species. Two linyphiid spider species were more closely linked to the maize-consuming prey in organically managed fields and one carabid species showed this pattern in conventionally managed fields. High litter decomposition levels and generalist predator numbers were only observed in wheat litter plots in organically managed fields. The addition of crop residues from the growing crop under organic management may therefore be a promising farming practice to simultaneously promote decomposition services and numbers of natural enemies. Future studies need to address this practice and potential effects on the litter decomposer predator food chain across sites that cover a range of different soil types and climatic conditions.
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