| 1. |
- Klionsky, Daniel J., et al.
(författare)
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Guidelines for the use and interpretation of assays for monitoring autophagy
- 2012
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Ingår i: Autophagy. - : Informa UK Limited. - 1554-8635 .- 1554-8627. ; 8:4, s. 445-544
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Forskningsöversikt (refereegranskat)abstract
- In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. A key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process vs. those that measure flux through the autophagy pathway (i.e., the complete process); thus, a block in macroautophagy that results in autophagosome accumulation needs to be differentiated from stimuli that result in increased autophagic activity, defined as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (in most higher eukaryotes and some protists such as Dictyostelium) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the field understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field.
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| 2. |
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| 3. |
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| 4. |
- Cars, Thomas, et al.
(författare)
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Extraction of Electronic Health Record Data in a Hospital Setting : Comparison of Automatic and Semi-Automatic Methods Using Anti-TNF Therapy as Model
- 2013
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Ingår i: Basic & Clinical Pharmacology & Toxicology. - : Wiley. - 1742-7835 .- 1742-7843. ; 112:6, s. 392-400
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Tidskriftsartikel (refereegranskat)abstract
- There is limited experience and methods for extractions of drug therapy data from electronic health records (EHR) in the hospital setting. We have therefore developed and evaluated completeness and consistency of an automatic versus a semi-automatic extraction procedure applied on prescribing and administration of the TNF inhibitor infliximab using a hospital EHR system in Karolinska University Hospital, Sweden. Using two different extraction methods (automatic and semi-automatic), all administered infusions of infliximab between 2007 and 2010 were extracted from a database linked to the EHR system. Extracted data included encrypted personal identity number (PIN), date of birth, sex, time of prescription/administration, healthcare units, prescribed/administered dose and time of admission/discharge. The primary diagnosis (ICD-10) for the treatment with infliximab was extracted by linking infliximab infusions to their corresponding treatment episode. A total of 13,590 infusions of infliximab were administered during the period of 2007 to 2010. Of those were 13,531 (99.6%) possible to link to a corresponding treatment episode, and a primary diagnosis was extracted for 13,530 infusions. Information on encrypted PIN, date of birth, time of prescription/administration, time of admission/discharge and healthcare unit was complete. Information about sex was missing in one patient only. Calculable information about dosage was extracted for 13,300 (98.3%) of all linked infusions. This methodological study showed the potential to extract drug therapy data in a hospital setting. The semi-automatic procedure produced an almost complete pattern of demographics, diagnoses and dosages for the treatment with infliximab.
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| 5. |
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| 6. |
- Carstensen, Jacob, et al.
(författare)
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Factors regulating the coastal nutrient filter in the Baltic Sea
- 2020
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 49:6, s. 1194-1210
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Tidskriftsartikel (refereegranskat)abstract
- The coastal zone of the Baltic Sea is diverse with strong regional differences in the physico-chemical setting. This diversity is also reflected in the importance of different biogeochemical processes altering nutrient and organic matter fluxes on the passage from land to sea. This review investigates the most important processes for removal of nutrients and organic matter, and the factors that regulate the efficiency of the coastal filter. Nitrogen removal through denitrification is high in lagoons receiving large inputs of nitrate and organic matter. Phosphorus burial is high in archipelagos with substantial sedimentation, but the stability of different burial forms varies across the Baltic Sea. Organic matter processes are tightly linked to the nitrogen and phosphorus cycles. Moreover, these processes are strongly modulated depending on composition of vegetation and fauna. Managing coastal ecosystems to improve the effectiveness of the coastal filter can reduce eutrophication in the open Baltic Sea.
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| 7. |
- Carstensen, Jacob, et al.
(författare)
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Long-Term and Seasonal Trends in Estuarine and Coastal Carbonate Systems
- 2018
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 32:3, s. 497-513
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Tidskriftsartikel (refereegranskat)abstract
- Coastal pH and total alkalinity are regulated by a diverse range of local processes superimposed on global trends of warming and ocean acidification, yet few studies have investigated the relative importance of different processes for coastal acidification. We describe long-term (1972-2016) and seasonal trends in the carbonate system of three Danish coastal systems demonstrating that hydrological modification, changes in nutrient inputs from land, and presence/absence of calcifiers can drastically alter carbonate chemistry. Total alkalinity was mainly governed by conservative mixing of freshwater (0.73-5.17mmolkg(-1)) with outer boundary concentrations (similar to 2-2.4mmolkg(-1)), modulated seasonally and spatially (similar to 0.1-0.2mmolkg(-1)) by calcifiers. Nitrate assimilation by primary production, denitrification, and sulfate reduction increased total alkalinity by almost 0.6mmolkg(-1) in the most eutrophic system during a period without calcifiers. Trends in pH ranged from -0.0088year(-1) to 0.021year(-1), the more extreme of these mainly driven by salinity changes in a sluice-controlled lagoon. Temperature increased 0.05 degrees Cyr(-1) across all three systems, which directly accounted for a pH decrease of 0.0008year(-1). Accounting for mixing, salinity, and temperature effects on dissociation and solubility constants, the resulting pH decline (0.0040year(-1)) was about twice the ocean trend, emphasizing the effect of nutrient management on primary production and coastal acidification. Coastal pCO(2) increased similar to 4 times more rapidly than ocean rates, enhancing CO2 emissions to the atmosphere. Indeed, coastal systems undergo more drastic changes than the ocean and coastal acidification trends are substantially enhanced from nutrient reductions to address coastal eutrophication.
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| 8. |
- Carstensen, Jacob, et al.
(författare)
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Policy Brief TRIACID: Acidification in Nordic Waters : Status, trends and implications for marine species
- 2018
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Recent studies on marine life show that the anthropogenic increase in atmospheric CO2 concentration can have negative impacts on growth and survival of groups of marine life such as corals and other calcifying organisms.Increased CO2 concentration in the atmosphere, and hence in the oceans, lead to decreasing pH or increasing acidification, a process known as ocean acidification (OA). During the last century, the CO2 concentration in the atmosphere has risen from around 280 ppm to 400 ppm; this has led to a pH decrease in the oceans of 0.1. OA currently takes place at a rate corresponding to approximately -0.02 pH unit per decade and an increase in CO2 at around 2 ppm per year. The projections for atmospheric CO2 concentration is an increase to around 1000 ppm at the end of the century, which will lower pH in the oceans by 0.3-0.4. Although this may appear relatively small, a decrease in pH of 0.1 corresponds to an increase in acidity (“free” protons) of 25%, and 0.3-0.4 corresponds to an increase of 200-250%.Coastal systems experience changes in pH over time exceeding those of the ocean by several orders of magnitude, but the field is poorly studied, and the spatial variation is large. The Baltic Sea is no exception to this. pH changes in the Baltic Sea are tightly coupled to nutrient input, alkalinity (AT) of freshwater sources in addition to increased CO2 levels and warming. Acidification trends vary substantially among coastal systems and time of year, but have been reported up to 10 times faster than OA. The TRIACID project has mapped acidification trends in the Baltic Sea during the past 40 years, in different regions, and identified areas with a general lack of data. The project has described spatial variation and trends in pH status, and the main drivers of changing pH have been identified. Given the spatial variation, the data gaps, and all the different drivers a detailed projection of the development is complicated but since we expect increasing CO2 concentration in the atmosphere, rising temperatures and decreasing nutrient input, the acidification trend will continue or accelerate in most of the region.
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| 9. |
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| 10. |
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| 11. |
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| 12. |
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| 13. |
- Ehrnsten, Eva, et al.
(författare)
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The meagre future of benthic fauna in a coastal sea-Benthic responses to recovery from eutrophication in a changing climate
- 2020
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Ingår i: Global Change Biology. - : Wiley. - 1354-1013 .- 1365-2486. ; 26:4, s. 2235-2250
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Tidskriftsartikel (refereegranskat)abstract
- Nutrient loading and climate change affect coastal ecosystems worldwide. Unravelling the combined effects of these pressures on benthic macrofauna is essential for understanding the future functioning of coastal ecosystems, as it is an important component linking the benthic and pelagic realms. In this study, we extended an existing model of benthic macrofauna coupled with a physical-biogeochemical model of the Baltic Sea to study the combined effects of changing nutrient loads and climate on biomass and metabolism of benthic macrofauna historically and in scenarios for the future. Based on a statistical comparison with a large validation dataset of measured biomasses, the model showed good or reasonable performance across the different basins and depth strata in the model area. In scenarios with decreasing nutrient loads according to the Baltic Sea Action Plan but also with continued recent loads (mean loads 2012-2014), overall macrofaunal biomass and carbon processing were projected to decrease significantly by the end of the century despite improved oxygen conditions at the seafloor. Climate change led to intensified pelagic recycling of primary production and reduced export of particulate organic carbon to the seafloor with negative effects on macrofaunal biomass. In the high nutrient load scenario, representing the highest recorded historical loads, climate change counteracted the effects of increased productivity leading to a hyperbolic response: biomass and carbon processing increased up to mid-21st century but then decreased, giving almost no net change by the end of the 21st century compared to present. The study shows that benthic responses to environmental change are nonlinear and partly decoupled from pelagic responses and indicates that benthic-pelagic coupling might be weaker in a warmer and less eutrophic sea.
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| 14. |
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| 15. |
- Gustafsson, Erik, et al.
(författare)
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Carbon cycling in the Baltic Sea - The fate of allochthonous organic carbon and its impact on air-sea CO2 exchange
- 2014
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 129, s. 289-302
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Tidskriftsartikel (refereegranskat)abstract
- A coupled physical-biogeochemical model (BALTSEM) is used to estimate carbon fluxes in the Baltic Sea over the 1980-2006 period. Budget calculations for organic carbon indicate that of the total allochthonous organic carbon (TOCT) supplied to the system, on average 56% is mineralized, 36% is exported out of the system, and the remainder is buried. River discharge is the main source of dissolved inorganic carbon (DIC) to the Baltic Sea. However, model results indicate that in the Gulf of Bothnia (northern Baltic Sea), the contribution to the DIC stock by TOCT mineralization is of the same order as direct river input of DIC In the Kattegat and Danish Straits (southwestern Baltic Sea) on the other hand, net uptake of atmospheric CO2 comprises the major DIC source. Despite large variations within the system, with net outgassing from some sub-basins and net absorption in others, the Baltic Sea as a whole was estimated to be a net sink for atmospheric CO2. Mineralization of allochthonous dissolved organic carbon (DOCT) influences air-sea CO2 exchange. A sensitivity study indicates that depending on the labile fraction of DOCT, the contribution from CO2 absorption to total external DIC sources can amount to 10-25%.
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| 16. |
- Gustafsson, Erik, et al.
(författare)
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Carbon cycling on the East Siberian Arctic Shelf – a change in air-sea CO2 flux induced by mineralization of terrestrial organic carbon
- 2017
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189.
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Tidskriftsartikel (refereegranskat)abstract
- Measurements from the SWERUS-C3 and ISSS-08 Arctic expeditions were used to calibrate and validate a new physical-biogeochemical model developed to quantify key carbon cycling processes on the East Siberian Arctic Shelf (ESAS). The model was used in a series of experimental simulations with the specific aim to investigate the pathways of terrestrial dissolved and particulate organic carbon (DOCter and POCter) supplied to the shelf. Rivers supply on average 8.5 Tg C yr−1 dissolved inorganic carbon (DIC), and further 8.5 and 1.1 Tg C yr−1 DOCter and POCter respectively. Based on observed and simulated DOC concentrations and stable isotope values (δ13CDOC) in shelf waters, we estimate that only some 20 % of the riverine DOCter is labile. According to our model results, an additional supply of approximately 14 Tg C yr−1 eroded labile POCter is however required to describe the observed stable isotope values of DIC (δ13CDIC). Degradation of riverine DOCter and POCter results in a 1.8 Tg C yr−1 reduction in the uptake of atmospheric CO2, while degradation of eroded POCter results in an additional 10 Tg C yr−1 reduction. Our calculations indicate nevertheless that the ESAS is an overall small net sink for atmospheric CO2 (1.7 Tg C yr−1). The external carbon sources are largely compensated by a net export from the shelf to the Arctic Ocean (31 Tg C yr−1), and to a smaller degree by a permanent burial in the sediments (2.7 Tg C yr−1).
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| 17. |
- Gustafsson, Erik, 1977-, et al.
(författare)
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Causes and consequences of acidification in the Baltic Sea : implications for monitoring and management
- 2023
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Ingår i: Scientific Reports. - 2045-2322. ; 13
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Tidskriftsartikel (refereegranskat)abstract
- Increasing atmospheric CO2 drives ocean acidification globally. In coastal seas, acidification trends can however be either counteracted or enhanced by other processes. Ecosystem effects of acidification are so far small in the Baltic Sea, but changes should be anticipated unless CO2 emissions are curbed. Possible future acidification trends in the Baltic Sea, conditional on CO2 emissions, climate change, and changes in productivity, can be assessed by means of model simulations. There are uncertainties regarding potential consequences for marine organisms, partly because of difficulties to assign critical thresholds, but also because of knowledge gaps regarding species’ capacity to adapt. Increased temporal and spatial monitoring of inorganic carbon system parameters would allow a better understanding of current acidification trends and also improve the capacity to predict possible future changes. An additional benefit is that such measurements also provide quantitative estimates of productivity. The technology required for precise measurements of the inorganic carbon system is readily available today. Regularly updated status evaluations of acidification, and the inorganic carbon system in general, would support management when assessing climate change effects, eutrophication or characteristics of the pelagic habitats. This would, however, have to be based on a spatially and temporally sufficient monitoring program.
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| 18. |
- Gustafsson, Erik, et al.
(författare)
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External total alkalinity loads versus internal generation : The influence of nonriverine alkalinity sources in the Baltic Sea
- 2014
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Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 28:11, s. 1358-1370
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Tidskriftsartikel (refereegranskat)abstract
- In this study we first present updated riverine total alkalinity (TA) loads to the various Baltic Sea sub-basins, based on monthly measurements in 82 of the major rivers that represent 85% of the total runoff. Simulations in the coupled physical-biogeochemical BALTSEM (BAltic sea Long-Term large Scale Eutrophication Model) model show that these river loads together with North Sea water inflows are not sufficient to reproduce observed TA concentrations in the system, demonstrating the large influence from internal sources. Budget calculations indicate that the required internal TA generation must be similar to river loads in magnitude. The nonriverine source in the system amounts to about 2.4mmolm(-2) d(-1) on average. We argue here that the majority of this source is related to denitrification together with unresolved sediment processes such as burial of reduced sulfur and/or silicate weathering. This hypothesis is supported by studies on sediment processes on a global scale and also by data from sediment cores in the Baltic Sea. In a model simulation with all internal TA sources and sinks switched on, the net absorption of atmospheric CO2 increased by 0.78mol C m(-2) yr(-1) compared to a simulation where TA was treated as a passive tracer. Our results clearly illustrate how pelagic TA sources together with anaerobic mineralization in coastal sediments generate a significant carbon sink along the aquatic continuum, mitigating CO2 evasions from coastal and estuarine systems.
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| 19. |
- Gustafsson, Erik, et al.
(författare)
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Future acidification of the Baltic Sea - A sensitivity study
- 2020
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 211
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Tidskriftsartikel (refereegranskat)abstract
- Future acidification of coastal seas will depend not only on the development of atmospheric CO2 partial pressure (pCO(2)), but also on changes in the catchment areas, exchange with the adjacent ocean, and internal cycling of carbon and nutrients. Here we use a coupled physical-biogeochemical Baltic Sea model to quantify the sensitivity of pH to changes both in external forcing and internal processes. The experiments include changes in runoff, supply of dissolved inorganic carbon (DIC) and total alkalinity (A(T)), nutrient loads, exchange between the Baltic and North Seas, and atmospheric pCO(2). We furthermore address the potential different future developments of runoff and river loads in boreal and continental catchments, respectively. Changes in atmospheric pCO(2) exert the strongest control on future pH according to our calculations. This CO2-induced acidification could be further enhanced in the case of desalination of the Baltic Sea, although increased concentrations of A(T) in the river runoff due to increased weathering to some extent could counteract acidification. Reduced nutrient loads and productivity would reduce the average annual surface water pH but at the same time slightly increase wintertime surface water pH (the annual pH minimum). The response time of surface water pH to sudden changes in atmospheric pCO(2) is approximately one month, whereas response times to changes in e.g. runoff and A(T)/DIC loads are more related to residence times of water and salt (> 30 years). It seems unlikely that the projected future increase in atmospheric pCO(2) and associated pH reduction could be fully counteracted by any of the other processes addressed in our experiments.
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| 20. |
- Gustafsson, Erik, et al.
(författare)
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Key processes in the coupled carbon, nitrogen, and phosphorus cycling of the Baltic Sea
- 2017
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Ingår i: Biogeochemistry. - : Springer Science and Business Media LLC. - 0168-2563 .- 1573-515X. ; 134:3, s. 301-317
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Tidskriftsartikel (refereegranskat)abstract
- In this study we examine pools of carbon (C), nitrogen (N), and phosphorus (P) in the Baltic Sea, both simulated and reconstructed from observations. We further quantify key fluxes in the C, N, and P cycling. Our calculations include pelagic reservoirs as well as the storage in the active sediment layer, which allows a complete coverage of the overall C, N, and P cycling on a system-scale. A striking property of C versus N and P cycling is that while the external supplies of total N and P (TN and TP) are largely balanced by internal removal processes, the total carbon (TC) supply is mainly compensated by a net export out of the system. In other words, external inputs of TN and TP are, in contrast to TC, rather efficiently filtered within the Baltic Sea. Further, there is a net export of TN and TP out of the system, but a net import of dissolved inorganic N and P (DIN and DIP). There is on the contrary a net export of both the organic and inorganic fractions of TC. While the pelagic pools of TC and TP are dominated by inorganic compounds, TN largely consists of organic N because allochthonous organic N is poorly degradable. There are however large basin-wise differences in C, N, and P elemental ratios as well as in inorganic versus organic fractions. These differences reflect both the differing ratios in external loads and differing oxygen conditions determining the redox-dependent fluxes of DIN and DIP.
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| 21. |
- Gustafsson, Erik, et al.
(författare)
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Modelling the C-13 and C-12 isotopes of inorganic and organic carbon in the Baltic Sea
- 2015
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Ingår i: Journal of Marine Systems. - : Elsevier BV. - 0924-7963 .- 1879-1573. ; 148, s. 122-130
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Tidskriftsartikel (refereegranskat)abstract
- In this study, C-12 and C-13 contents of all carbon containing state variables (dissolved inorganic and organic carbon, detrital carbon, and the carbon content of autotrophs and heterotrophs) have for the first time been explicitly included in a coupled physical-biogeochemical Baltic Sea model. Different processes in the carbon cycling have distinct fractionation values, resulting in specific isotopic fingerprints. Thus, in addition to simulating concentrations of different tracers, our new model formulation improves the possibility to constrain the rates of processes such as CO2 assimilation, mineralization, and air-sea exchange. We demonstrate that phytoplankton production and respiration, and the related air-sea CO2 fluxes, are to a large degree controlling the isotopic composition of organic and inorganic carbon in the system. The isotopic composition is further, but to a lesser extent, influenced by river loads and deep water inflows as well as transformation of terrestrial organic carbon within the system. Changes in the isotopic composition over the 20th century have been dominated by two processes the preferential release of C-12 to the atmosphere in association with fossil fuel burning, and the eutrophication of the Baltic Sea related to increased nutrient loads under the second half of the century.
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| 22. |
- Gustafsson, Erik, et al.
(författare)
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OMAI – Assessing acidification in the Baltic Sea, monitoring and scientific basis
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- In marine and brackish waters, the acidity of the water is mainly controlled by the inorganic carbon system. Anthropogenic CO2 emissions will – unless reduced – gradually move the Baltic Sea towards a state where acidification becomes harmful for some organisms. The effect is caused by the uptake of CO2 in the water, but can be further enhanced by other climate effects, such as increased water temperature and a possible freshening of the sea water. This is expected to lead to changes in species composition, both directly (competitive advantages/disadvantages) and indirectly (altered food availability), potentially influencing ecosystem functioning.Coastal seas, such as the Baltic Sea, are highly influenced by their catchment areas, which means that pH dynamics is generally more complex than in the open ocean. The reason is that pH, in addition to the response to increasing CO2, is also influenced by changes in hydrology and changes in the supply of carbon and nutrients. High-productive waters typically experience larger seasonal pH variations than low-productive waters, with higher pH peaks in spring/summer and also a more pronounced pH decline in winter. The comparatively weak long-term acidification trend can be masked behind much larger short-term variations. Furthermore, since acidification is a slow process, organisms can to varying degrees adapt to the changes.Model simulations performed as a part of the OMAI (Operational Marine Acidification Indicator) project indicate that the expected acidification in the Baltic Sea generally follows the same trajectory as the open oceans, with a pH decline of almost 0.4 by year 2100 and a further decline of 0.3 by year 2300 in the worst-case scenario. Due to large regional differences in the area, the annual mean pH in the Bothnian Bay might decline from present-day 7.8 to 7.4 by year 2100, whereas in the Gotland Sea and Southern Kattegat mean pH could decline from present-day 8.1 to 7.7. The degree of eutrophication has a comparatively small effect on the annual mean pH, but on the other hand a considerable impact on the seasonal amplitude and thus minimum and maximum values.The complex situation in the Baltic Sea gives a strong incentive to improve the temporal and spatial coverage of acidification monitoring. This would broaden the understanding of current acidification trends and also improve the capacity to predict future changes. An indicator for acidification in the Baltic Sea is currently under development. Monitoring of parameters relevant for acidification, i.e., the inorganic carbon system parameters, would as an added value also provide an additional handle in terms of assessing changes in primary production and eutrophication trends.
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| 23. |
- Gustafsson, Erik, et al.
(författare)
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Sedimentary alkalinity generation and long-term alkalinity development in the Baltic Sea
- 2019
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Ingår i: Biogeosciences. - : Copernicus GmbH. - 1726-4170 .- 1726-4189. ; 16:2, s. 437-456
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Tidskriftsartikel (refereegranskat)abstract
- Enhanced release of alkalinity from the seafloor, principally driven by anaerobic degradation of organic matter under low-oxygen conditions and associated secondary redox reactions, can increase the carbon dioxide (CO2) buffering capacity of seawater and therefore oceanic CO2 uptake. The Baltic Sea has undergone severe changes in oxygenation state and total alkalinity (TA) over the past decades. The link between these concurrent changes has not yet been investigated in detail. A recent system-wide TA budget constructed for the past 50 years using BALTSEM, a coupled physical-biogeochemical model for the whole Baltic Sea area, revealed an unknown TA source. Here we use BALTSEM in combination with observational data and one-dimensional reactive transport modelling of sedimentary processes in the Fårö Deep, a deep Baltic Sea basin, to test whether sulfate reduction coupled to iron (Fe) sulfide burial can explain the missing TA source in the Baltic Proper. We calculated that this burial can account for 26% of the missing source in this basin, with the remaining TA possibly originating from unknown river inputs or submarine groundwater discharge. We also show that temporal variability in the input of Fe to the sediments since the 1970s drives changes in sulfur burial in the Fårö Deep, suggesting that Fe availability is the ultimate limiting factor for TA generation under anoxic conditions. The implementation of projected climate change and two nutrient load scenarios for the 21st century in BALTSEM shows that reducing nutrient loads will improve deep water oxygen conditions, but at the expense of lower surface water TA concentrations, CO2 buffering capacities and faster acidification. When these changes additionally lead to a decrease in Fe inputs to the sediment of the deep basins, anaerobic TA generation will be reduced even further, thus exacerbating acidification. This work highlights that Fe dynamics play a key role in the release of TA from sediments where Fe sulfide formation is limited by Fe availability, as exemplified for the Baltic Sea. Moreover, it demonstrates that burial of Fe sulfides should be included in TA budgets of low oxygen basins.
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| 24. |
- Gustafsson, Erik, 1977, et al.
(författare)
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The air-water CO2 exchange of a coastal sea— A sensitivity study on factors that influence the absorption and outgassing of CO2 in the Baltic Sea
- 2015
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Ingår i: Journal of Geophysical Research - Oceans. - 0148-0227 .- 2156-2202 .- 2169-9275 .- 2169-9291. ; 120:8, s. 5342-5357
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Tidskriftsartikel (refereegranskat)abstract
- In this study, the BALTSEM model is used to estimate how air-water CO2 fluxes in the Baltic Sea respond to parameterizations of organic alkalinity (Aorg), gas transfer, and phytoplankton growth, and further to changes in river loads. The forcing data include the most complete compilation of Baltic river loads for dissolved inorganic and organic carbon (DIC and DOC) and total alkalinity (TA). In addition, we apply the most recent estimates of internal TA generation in the system. Our results clearly demonstrate how airwater CO2 fluxes of a coastal sea depend on river loads of carbon, TA, and nutrients as well the freshwater import itself. Long-term changes in DIC loads are shown to be compensated by corresponding changes in air-water CO2 exchange. By adding Aorg, a discrepancy in the carbonate system calculations was removed, and the simulated net CO2 absorption of the system decreased by 11%. A new parameterization for cyanobacteria growth significantly improved the seasonal development of pCO2 in the central Baltic Sea, although the net effect on CO2 fluxes was below 5%. By applying either a linear, quadratic, or cubic wind speed dependence for gas transfer, the long-term net CO2 exchange was adjusted by less than 5%. There is no clear indication that any one of these parameterizations provides a more accurate estimate of CO2 fluxes than the other two. Our findings are applicable in other coastal areas that are heavily influenced by river loads of TA, DIC, and DOC.
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| 25. |
- Hermans, Martijn, et al.
(författare)
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Impact of natural re-oxygenation on the sediment dynamics of manganese, iron and phosphorus in a euxinic Baltic Sea basin
- 2019
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Ingår i: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 246, s. 174-196
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Tidskriftsartikel (refereegranskat)abstract
- The Baltic Sea is characterized by the largest area of hypoxic (oxygen (O2) < 2 mg L−1) bottom waters in the world’s ocean induced by human activities. Natural ventilation of these O2-depleted waters largely depends on episodic Major Baltic Inflows from the adjacent North Sea. In 2014 and 2015, two such inflows led to a strong rise in O2 and decline in phosphate (HPO42−) in waters below 125 m depth in the Eastern Gotland Basin. This provided the opportunity to assess the impact of such re-oxygenation events on the cycles of manganese (Mn), iron (Fe) and phosphorus (P) in the sediment for the first time. We demonstrate that the re-oxygenation induced the activity of sulphur (S)-oxidising bacteria, known as Beggiatoaceae in the surface sediment where a thin oxic and suboxic layer developed. At the two deepest sites, strong enrichments of total Mn and to a lesser extent Fe oxides and P were observed in this surface layer. A combination of sequential sediment extractions and synchrotron-based X-ray spectroscopy revealed evidence for the abundant presence of P-bearing rhodochrosite and Mn(II) phosphates. In contrast to what is typically assumed, the formation of Fe oxides in the surface sediment was limited. We attribute this lack of Fe oxide formation to the high flux of reductants, such as sulphide, from deeper sediments which allows Fe(II) in the form of FeS to be preserved and restricts the penetration of O2 into the sediment. We estimate that enhanced P sequestration in surface sediments accounts for only ∼5% of water column HPO42− removal in the Eastern Gotland Basin linked to the recent inflows. The remaining HPO42− was transported to adjacent areas in the Baltic Sea. Our results highlight that the benthic O2 demand arising from the accumulation of organic-rich sediments over several decades, the legacy of hypoxia, has major implications for the biogeochemical response of euxinic basins to re-oxygenation. In particular, P sequestration in the sediment in association with Fe oxides is limited. This implies that artificial ventilation projects that aim at removing water column HPO42− and thereby improving water quality in the Baltic Sea will likely not have the desired effect.
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| 26. |
- Humborg, Christoph, et al.
(författare)
-
Sea-air exchange patterns along the central and outer East Siberian Arctic Shelf as inferred from continuous CO2, stable isotope, and bulk chemistry measurements
- 2017
-
Ingår i: Global Biogeochemical Cycles. - 0886-6236 .- 1944-9224. ; 31:7, s. 1173-1191
-
Tidskriftsartikel (refereegranskat)abstract
- This large-scale quasi-synoptic study gives a comprehensive picture of sea-air CO 2 fluxes during the melt season in the central and outer Laptev Sea (LS) and East Siberian Sea (ESS). During a 7 week cruise we compiled a continuous record of both surface water and air CO 2 concentrations, in total 76,892 measurements. Overall, the central and outer parts of the ESAS constituted a sink for CO 2 , and we estimate a median uptake of 9.4 g C m -2 yr -1 or 6.6 Tg C yr -1 . Our results suggest that while the ESS and shelf break waters adjacent to the LS and ESS are net autotrophic systems, the LS is a net heterotrophic system. CO 2 sea-air fluxes for the LS were 4.7 g C m -2 yr -1 , and for the ESS we estimate an uptake of 7.2 g C m -2 yr -1 . Isotopic composition of dissolved inorganic carbon (δ 13 C DIC and δ 13 C CO2 ) in the water column indicates that the LS is depleted in δ 13 C DIC compared to the Arctic Ocean (ArcO) and ESS with an offset of 0.5‰ which can be explained by mixing of δ 13 C DIC -depleted riverine waters and 4.0 Tg yr -1 respiration of OC ter ; only a minor part (0.72 Tg yr -1 ) of this respired OC ter is exchanged with the atmosphere. Property-mixing diagrams of total organic carbon and isotope ratio (δ 13 C SPE-DOC ) versus dissolved organic carbon (DOC) concentration diagram indicate conservative and nonconservative mixing in the LS and ESS, respectively. We suggest land-derived particulate organic carbon from coastal erosion as an additional significant source for the depleted δ 13 C DIC .
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| 27. |
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| 28. |
- Löfgren, Martin, 1975-
(författare)
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The Leader of the Pack : A Service Perspective on Packaging and Customer Satisfaction
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Almost everything we as consumers buy in a store has a package. Packages have many functions – some, if not all, present marketers with the opportunity to gain competitive advantages. The packaging influences the usage behavior long after it has influenced the purchase, therefore it is an interesting empirical context to study within the field of marketing. Nevertheless, academic attention to packaging has been sparse over the last two decades even though the industry focus on packaging as a strategic tool has grown over that same period. Exceptions in the marketing literature are investigations of packaging and brand communication, advertisement-package coordination, and packaging size and shape. In contrast to the traditional approach that views packaging as a complimenting non-product-related attribute, it is suggested in this thesis that packaging is a product-related attribute that does affect the customers’ experiences of products.The overall aim of this thesis is to develop and test theoretical models and provide empirical evidence of customer experiences in the context of packaging from a service perspective. To study packaging from a service perspective is relevant for several reasons. One reason is that packaging can have several functions, which include more than the physical package. Another reason is that packages are carriers of information that is interpreted by customers. The combination of function, information, the physical package, and its content creates the total customer experience.The results of this thesis provide increased knowledge about packaging and customer experiences from a service perspective. On an attribute level, quality attributes such as protection and usability are categorized according to Kano’s theory of attractive quality. The results show that customers’ evaluations of packages are multi-dimensional. On a comprehensive or an overall level, structural equation modeling is used to investigate the consumption process. We conclude that the quality attributes of packages need to be designed to display quality both on the shelf in a store and during usage and consumption at both the attribute and comprehensive level.
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| 29. |
- Meier, H. E. Markus, et al.
(författare)
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Assessment of Eutrophication Abatement Scenarios for the Baltic Sea by Multi-Model Ensemble Simulations
- 2018
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 5
-
Tidskriftsartikel (refereegranskat)abstract
- To assess the impact of the implementation of the Baltic Sea Action Plan (BSAP) on the future environmental status of the Baltic Sea, available uncoordinated multi-model ensemble simulations for the Baltic Sea region for the twenty-first century were analyzed. The scenario simulations were driven by regionalized global general circulation model (GCM) data using several regional climate system models and forced by various future greenhouse gas emission and air- and river-borne nutrient load scenarios following either reference conditions or the BSAP. To estimate uncertainties in projections, the largest ever multi-model ensemble for the Baltic Sea comprising 58 transient simulations for the twenty-first century was assessed. Data from already existing simulations from different projects including regionalized GCM simulations of the third and fourth assessment reports of the Intergovernmental Panel on Climate Change based on the corresponding Coupled Model Intercomparison Projects, CMIP3 and CMIP5, were collected.Various strategies to weigh the ensemble members were tested and the results for ensemble mean changes between future and present climates are shown to be robust with respect to the chosen metric. Although (1) the model simulations during the historical period are of different quality and (2) the assumptions on nutrient load levels during present and future periods differ between models considerably, the ensemble mean changes in biogeochemical variables in the Baltic proper with respect to nutrient load reductions are similar between the entire ensemble and a subset consisting only of the most reliable simulations.Despite the large spread in projections, the implementation of the BSAP will lead to a significant improvement of the environmental status of the Baltic Sea according to both weighted and unweighted ensembles. The results emphasize the need for investigating ensembles with many members and rigorous assessments of models’ performance.
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| 30. |
- Meier, H. E. Markus, et al.
(författare)
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Assessment of Uncertainties in Scenario Simulations of Biogeochemical Cycles in the Baltic Sea
- 2019
-
Ingår i: Frontiers in Marine Science. - : Frontiers Media SA. - 2296-7745. ; 6
-
Forskningsöversikt (refereegranskat)abstract
- Following earlier regional assessment studies, such as the Assessment of Climate Change for the Baltic Sea Basin and the North Sea Region Climate Change Assessment, knowledge acquired from available literature about future scenario simulations of biogeochemical cycles in the Baltic Sea and their uncertainties is assessed. The identification and reduction of uncertainties of scenario simulations are issues for marine management. For instance, it is important to know whether nutrient load abatement will meet its objectives of restored water quality status in future climate or whether additional measures are required. However, uncertainties are large and their sources need to be understood to draw conclusions about the effectiveness of measures. The assessment of sources of uncertainties in projections of biogeochemical cycles based on authors' own expert judgment suggests that the biggest uncertainties are caused by (1) unknown current and future bioavailable nutrient loads from land and atmosphere, (2) the experimental setup (including the spin up strategy), (3) differences between the projections of global and regional climate models, in particular, with respect to the global mean sea level rise and regional water cycle, (4) differing model-specific responses of the simulated biogeochemical cycles to long-term changes in external nutrient loads and climate of the Baltic Sea region, and (5) unknown future greenhouse gas emissions. Regular assessments of the models' skill (or quality compared to observations) for the Baltic Sea region and the spread in scenario simulations (differences among projected changes) as well as improvement of dynamical downscaling methods are recommended.
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| 31. |
- Soerensen, Anne. L., et al.
(författare)
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Eutrophication Increases Phytoplankton Methylmercury Concentrations in a Coastal Sea-A Baltic Sea Case Study
- 2016
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 50:21, s. 11787-11796
-
Tidskriftsartikel (refereegranskat)abstract
- Eutrophication is expanding worldwide, but its implication for production and bioaccumulation of neurotoxic monomethylmercury (MeHg) is unknown. We developed a mercury (Hg) biogeochemical model for the Baltic Sea and used it to investigate the impact of eutrophication on phytoplankton MeHg concentrations. For model evaluation, we measured total methylated Hg (MeHgT) in the Baltic Sea and found low concentrations (39 +/- 16 fM) above the halocline and high concentrations in anoxic waters (1249 +/- 369 fM). To close the Baltic Sea MeHgT budget, we inferred an average normoxic water column HgII methylation rate constant of 2 x 10-4 d-1. We used the model to compare Baltic Seas present-day (2005-2014) eutrophic state to an oligo/mesotrophic scenario. Eutrophication increases primary production and export of organic matter and associated Hg to the sediment effectively removing Hg from the active biogeochemical cycle; this results in a 27% lower present-day water column Hg reservoir. However, increase in organic matter production and remineralization stimulates microbial Hg methylation resulting in a seasonal increase in both water and phytoplankton MeHg reservoirs above the halocline. Previous studies of systems dominated by external MeHg sources or benthic production found eutrophication to decrease MeHg levels in plankton. This Baltic Sea study shows that in systems with MeHg production in the normoxic water column eutrophication can increase phytoplankton MeHg content.
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| 32. |
- Undeman, Emma, et al.
(författare)
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A novel modeling tool with multi-stressor functionality for organic contaminant transport and fate in the Baltic Sea
- 2014
-
Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; 497, s. 382-391
-
Tidskriftsartikel (refereegranskat)abstract
- The coupled physical-biogeochemical model BALTSEM, previously used to assess nutrient/carbon cycles and eutrophication in the Baltic Sea, has been expanded to include algorithms for calculations of organic contaminant environmental transport and fate. This novel model version (BALTSEM-POP) is evaluated for polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins/dibenzofurans (PCDD/Fs) and hexachlorobenzene (HCB) in Baltic Sea surface water and sediment. Modeled dissolved concentrations are usually within a factor of 2-4 of observed concentrations, however with larger deviations for furans. Calculated concentrations in particulate organic matter are less accurate (within factors of 1-700), likely due to errors in estimated pelagic biomass, particulate matter-water partitioning, and large natural variability in field data. Concentrations in sediments are usually predicted within a factor of 6. The good performance of the model illustrates its usefulness for exploration of contaminant fate in response to variations in nutrient input and climatic conditions in the Baltic Sea marine environment.
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| 33. |
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| 34. |
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| 35. |
- Ahmadi, Shilan Seyed, et al.
(författare)
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Effect of liraglutide on anthropometric measurements, sagittal abdominal diameter and adiponectin levels in people with type 2 diabetes treated with multiple daily insulin injections: evaluations from a randomized trial (MDI-liraglutide study 5)
- 2019
-
Ingår i: Obesity Science and Practice. - : Wiley. - 2055-2238. ; 5:2, s. 130-140
-
Tidskriftsartikel (refereegranskat)abstract
- Aim Use of the glucagon-like peptide 1 receptor agonist liraglutide has been shown to reduce weight. Different types of anthropometric measurements can be used to measure adiposity. This study evaluated the effect of liraglutide on sagittal abdominal diameter, waist circumference, waist-to-hip ratio and adiponectin levels in people with type 2 diabetes (T2D) treated with multiple daily insulin injections (MDI). Materials and methods In the multicentre, double-blind, placebo-controlled MDI-liraglutide trial, 124 individuals with T2D treated with MDI were randomized to either liraglutide or placebo. Basal values of weight, waist circumference, waist-to-hip ratio, sagittal abdominal diameter and adiponectin were compared with measurements at 12 and 24 weeks after randomization. Results Baseline-adjusted mean weight loss was 3.8 +/- 2.9 kg greater in liraglutide than placebo-treated individuals (p < 0.0001). Waist circumference was reduced by 2.9 +/- 4.3 cm and 0.2 +/- 3.6 cm in the liraglutide and placebo groups, respectively, after 24 weeks (baseline-adjusted mean difference: 2.6 +/- 4.0 cm, p = 0.0005). Corresponding reductions in sagittal abdominal diameter were 1.1 +/- 1.7 cm and 0.0 +/- 1.8 cm (baseline-adjusted mean difference: 1.1 +/- 1.7 cm, p = 0.0008). Hip circumference was reduced in patients randomized to liraglutide (baseline-adjusted mean difference between treatment groups: 2.8 +/- 3.8 cm, p = 0.0001), but there was no significant difference between the groups in either waist-to-hip ratio (baseline-adjusted mean difference: 0.0 +/- 0.04 cm, p = 0.51) or adiponectin levels (baseline-adjusted mean difference: 0.8 +/- 3.3 mg L-1, p = 0.17). Lower HbA1c and mean glucose levels measured by masked continuous glucose monitoring at baseline were associated with greater effects of liraglutide on reductions in waist circumference and sagittal abdominal diameter. Conclusions In patients with T2D, adding liraglutide to MDI may reduce abdominal and hip obesity to a similar extent, suggesting an effect on both visceral and subcutaneous fat. Liraglutide had greater effects on reducing abdominal obesity in patients with less pronounced long-term hyperglycaemia but did not affect adiponectin levels.
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| 36. |
- Andersen, Jesper H., et al.
(författare)
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Long-term temporal and spatial trends in eutrophication status of the Baltic Sea
- 2017
-
Ingår i: Biological Reviews. - : Wiley. - 1464-7931 .- 1469-185X. ; 92:1, s. 135-149
-
Tidskriftsartikel (refereegranskat)abstract
- Much of the Baltic Sea is currently classified as 'affected by eutrophication'. The causes for this are twofold. First, current levels of nutrient inputs (nitrogen and phosphorus) from human activities exceed the natural processing capacity with an accumulation of nutrients in the Baltic Sea over the last 50-100 years. Secondly, the Baltic Sea is naturally susceptible to nutrient enrichment due to a combination of long retention times and stratification restricting ventilation of deep waters. Here, based on a unique data set collated from research activities and long-term monitoring programs, we report on the temporal and spatial trends of eutrophication status for the open Baltic Sea over a 112-year period using the HELCOM Eutrophication Assessment Tool (HEAT 3.0). Further, we analyse variation in the confidence of the eutrophication status assessment based on a systematic quantitative approach using coefficients of variation in the observations. The classifications in our assessment indicate that the first signs of eutrophication emerged in the mid-1950s and the central parts of the Baltic Sea changed from being unaffected by eutrophication to being affected. We document improvements in eutrophication status that are direct consequences of long-term efforts to reduce the inputs of nutrients. The reductions in both nitrogen and phosphorus loads have led to large-scale alleviation of eutrophication and to a healthier Baltic Sea. Reduced confidence in our assessment is seen more recently due to reductions in the scope of monitoring programs. Our study sets a baseline for implementation of the ecosystem-based management strategies and policies currently in place including the EU Marine Strategy Framework Directives and the HELCOM Baltic Sea Action Plan.
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| 37. |
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| 38. |
- Bargholtz, Chr., et al.
(författare)
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Measurement of the eta -> pi(+)pi(-)e(+)e(-) decay branching ratio
- 2007
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 644:5-6, s. 299-303
-
Tidskriftsartikel (refereegranskat)abstract
- The reaction pd -> He-3 eta at threshold was used to provide a clean source of eta mesons for decay studies with the WASA detector at CELSIUS. The branching ratio of the decay eta -> pi(+)pi(-)e(+)e(-) is measured to be (4.3 +/- 1.3 +/- 0.4) x 10(-4).
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| 39. |
- Bargholtz, Chr., et al.
(författare)
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The WASA detector facility at CELSIUS
- 2008
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Ingår i: Nuclear Instruments and Methods in Physics Research Section A. - : Elsevier BV. - 0168-9002 .- 1872-9576. ; 594:3, s. 339-350
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Tidskriftsartikel (refereegranskat)abstract
- The WASA 4 pi multidetector system, aimed at investigating light meson production in light ion collisions and eta meson rare decays at the CELSIUS storage ring in Uppsala is presented. A unique feature of the system is the use of hydrogen pellets as internal targets for the first time. A detailed description of the design, together with the anticipated and achieved performance parameters are given. (C) 2008 Elsevier B.V. All rights reserved.
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| 40. |
- Barucca, G., et al.
(författare)
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Study of excited Ξ baryons with the P¯ ANDA detector
- 2021
-
Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
-
Tidskriftsartikel (refereegranskat)abstract
- The study of baryon excitation spectra provides insight into the inner structure of baryons. So far, most of the world-wide efforts have been directed towards N∗ and Δ spectroscopy. Nevertheless, the study of the double and triple strange baryon spectrum provides independent information to the N∗ and Δ spectra. The future antiproton experiment P¯ANDA will provide direct access to final states containing a Ξ¯ Ξ pair, for which production cross sections up to μb are expected in p¯p reactions. With a luminosity of L= 10 31 cm- 2 s- 1 in the first phase of the experiment, the expected cross sections correspond to a production rate of ∼106events/day. With a nearly 4 π detector acceptance, P¯ANDA will thus be a hyperon factory. In this study, reactions of the type p¯p → Ξ¯ +Ξ∗ - as well as p¯p → Ξ¯ ∗ +Ξ- with various decay modes are investigated. For the exclusive reconstruction of the signal events a full decay tree fit is used, resulting in reconstruction efficiencies between 3 and 5%. This allows high statistics data to be collected within a few weeks of data taking.
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| 41. |
- Barucca, G., et al.
(författare)
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The potential of Λ and Ξ- studies with PANDA at FAIR
- 2021
-
Ingår i: European Physical Journal A. - : Springer Nature. - 1434-6001 .- 1434-601X. ; 57:4
-
Tidskriftsartikel (refereegranskat)abstract
- The antiproton experiment PANDA at FAIR is designed to bring hadron physics to a new level in terms of scope, precision and accuracy. In this work, its unique capability for studies of hyperons is outlined. We discuss ground-state hyperons as diagnostic tools to study non-perturbative aspects of the strong interaction, and fundamental symmetries. New simulation studies have been carried out for two benchmark hyperon-antihyperon production channels: p¯ p→ Λ¯ Λ and p¯ p→ Ξ¯ +Ξ-. The results, presented in detail in this paper, show that hyperon-antihyperon pairs from these reactions can be exclusively reconstructed with high efficiency and very low background contamination. In addition, the polarisation and spin correlations have been studied, exploiting the weak, self-analysing decay of hyperons and antihyperons. Two independent approaches to the finite efficiency have been applied and evaluated: one standard multidimensional efficiency correction approach, and one efficiency independent approach. The applicability of the latter was thoroughly evaluated for all channels, beam momenta and observables. The standard method yields good results in all cases, and shows that spin observables can be studied with high precision and accuracy already in the first phase of data taking with PANDA.
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| 42. |
- Bashkanov, M., et al.
(författare)
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Double-Pionic Fusion of Nuclear Systems and the "ABC" Effect : Approaching a Puzzle by Exclusive and Kinematically Complete Measurements
- 2009
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 102:5, s. 052301-
-
Tidskriftsartikel (refereegranskat)abstract
- The ABC effect-a puzzling low-mass enhancement in the pi pi invariant mass spectrum, first observed by Abashian, Booth, and Crowe-is well known from inclusive measurements of two-pion production in nuclear fusion reactions. Here we report on the first exclusive and kinematically complete measurements of the most basic double-pionic fusion reaction pn -> d pi(0)pi(0) at beam energies of 1.03 and 1.35 GeV. The measurements, which have been carried out at CELSIUS-WASA, reveal the ABC effect to be a (pi pi)(I=L=0) channel phenomenon associated with both a resonancelike energy dependence in the integral cross section and the formation of a Delta Delta system in the intermediate state. A corresponding simple s-channel resonance ansatz provides a surprisingly good description of the data.
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| 43. |
- Bashkanov, M., et al.
(författare)
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Exclusive measurements of pd -> He-3 pi pi : The ABC effect revisited
- 2006
-
Ingår i: Physics Letters B. - : Elsevier BV. - 0370-2693 .- 1873-2445. ; 637:4-5, s. 223-228
-
Tidskriftsartikel (refereegranskat)abstract
- Exclusive measurements of the reactions pd -> He-3 pi(+)7 pi(-) and pd -> He-3 pi(0)pi(0) have been carried out at T-p = 0.893 GeV at the CELSIUS storage ring using the WASA detector. The pi(+)pi(-) channel evidences a pronounced enhancement at low invariant pi pi masses-as anticipated from previous inclusive measurements of the ABC effect. This enhancement is seen to be even much larger in the isoscalar pi(0)pi(0) channel. The differential distributions prove this enhancement to be of scalar-isoscalar nature. Delta Delta calculations give a good description of the data, if a boundstate condition is imposed for the intermediate Delta Delta system.
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| 44. |
- Bashkanov, M., et al.
(författare)
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Low-mass pi pi enhancement in baryonic pi pi production : ABC effect revised by exclusive measurements
- 2007
-
Ingår i: International Journal of Modern Physics A. - 0217-751X .- 1793-656X. ; 22:2-3, s. 625-628
-
Tidskriftsartikel (refereegranskat)abstract
- The ABC effect - a puzzling threshold enhancement in the ππ invariant mass spectrum of double-pionic fusion to nuclear bound states - has been investigated since 40 years by inclusive measurements without providing a conclusive interpretation. First exclusive measurements to this topic have now been carried out at CELSIUS-WASA. They confirm a huge ππ threshold enhancement, prove it to be of scalar-isoscalar nature, i.e., a σ-channel phenomenon and reveal the theoretically predicted high-mass enhancement in inclusive spectra to be of πππ rather than of ππ nature - falsifying thus corresponding model predictions for the ABC effect. From the kinematically complete data samples we infer that the interaction between the two Δ particles created in this process is of crucial importance.
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| 45. |
- Bashkanov, M., et al.
(författare)
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Measurement of the slope parameter for the η → 3π0 decay in the pp → ppη reaction
- 2007
-
Ingår i: Physical Review C. Nuclear Physics. - 0556-2813 .- 1089-490X. ; 76:4, s. 048201-
-
Tidskriftsartikel (refereegranskat)abstract
- The CELSIUS-WASA setup is used to measure the 3π0 decay of η mesons produced in pp interactions with beam kinetic energies of 1.36 and 1.45 GeV. The efficiency-corrected Dalitz plot and density distributions for this decay are shown, together with a fit of the quadratic slope parameter α yielding α = −0.026 ± 0.010(stat) ± 0.010(syst). This value is compared to recent experimental results and theoretical predictions.
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| 46. |
- Bashkanov, M., et al.
(författare)
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Two-pion production in proton-proton collisions
- 2004
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Ingår i: Hadron Spectroscopy, Tenth International Conference on Hadron Spectrscopy, Aschaffenburg, Germany 31 August - 6 September 2003. - 0735401977 ; , s. 241-244
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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| 47. |
- Bauer, Barbara, et al.
(författare)
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Food web and fisheries in the future Baltic Sea
- 2019
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Ingår i: Ambio. - : Springer Science and Business Media LLC. - 0044-7447 .- 1654-7209. ; 48:11, s. 1337-1349
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Tidskriftsartikel (refereegranskat)abstract
- We developed numerical simulations of potential future ecological states of the Baltic Sea ecosystem at the end of century under five scenarios. We used a spatial food web (Ecospace) model, forced by a physical-biogeochemical model. The scenarios are built on consistent storylines that describe plausible developments of climatic and socioeconomic factors in the Baltic Sea region. Modelled species diversity and fish catches are driven by climate- and nutrient load-related changes in habitat quality and by fisheries management strategies. Our results suggest that a scenario including low greenhouse gas concentrations and nutrient pollution and ecologically focused fisheries management results in high biodiversity and catch value. On the other hand, scenarios envisioning increasing societal inequality or economic growth based on fossil fuels, high greenhouse gas emissions and high nutrient loads result in decreased habitat quality and diminished biodiversity. Under the latter scenarios catches are high but they predominantly consist of lower-valued fish.
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| 48. |
- Berlowski, M., et al.
(författare)
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Measurement of eta meson decays into lepton-antilepton pairs
- 2008
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Ingår i: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 77:3, s. 032004-
-
Tidskriftsartikel (refereegranskat)abstract
- A search for rare lepton decays of the eta meson was performed using the WASA detector at CELSIUS. Two candidates for double Dalitz decay eta -> e(+)e(-)e(+)e(-) events are reported with a background of 1.3 +/- 0.2 events. This allows to set an upper limit to the branching ratio of 9.7x10(-5) (90% CL). The branching ratio for the decay eta -> e(+)e(-)gamma is determined to (7.8 +/- 0.5(stat)+/- 0.8(syst))x10(-3) in agreement with world average value. An upper limit (90% CL) for the branching ratio for the eta -> e(+)e(-) decay is 2.7x10(-5) and a limit for the sum of the eta ->mu(+)mu(-)mu(+)mu(-) and eta ->pi(+)pi(-)mu(+)mu(-) decays is 3.6x10(-4).
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| 49. |
- Bi, Zhaoxia, et al.
(författare)
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High In-content InGaN nano-pyramids : Tuning crystal homogeneity by optimized nucleation of GaN seeds
- 2018
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Ingår i: Journal of Applied Physics. - : AIP Publishing. - 0021-8979 .- 1089-7550. ; 123:2
-
Tidskriftsartikel (refereegranskat)abstract
- Uniform arrays of submicron hexagonal InGaN pyramids with high morphological and material homogeneity, reaching an indium composition of 20%, are presented in this work. The pyramids were grown by selective area metal-organic vapor phase epitaxy and nucleated from small openings in a SiN mask. The growth selectivity was accurately controlled with diffusion lengths of the gallium and indium species, more than 1 μm on the SiN surface. High material homogeneity of the pyramids was achieved by inserting a precisely formed GaN pyramidal seed prior to InGaN growth, leading to the growth of well-shaped InGaN pyramids delimited by six equivalent 10 1 ̄ 1 facets. Further analysis reveals a variation in the indium composition to be mediated by competing InGaN growth on two types of crystal planes, 10 1 ̄ 1 and (0001). Typically, the InGaN growth on 10 1 ̄ 1 planes is much slower than on the (0001) plane. The formation of the (0001) plane and the growth of InGaN on it were found to be dependent on the morphology of the GaN seeds. We propose growth of InGaN pyramids seeded by 10 1 ̄ 1-faceted GaN pyramids as a mean to avoid InGaN material grown on the otherwise formed (0001) plane, leading to a significant reduction of variations in the indium composition in the InGaN pyramids. The InGaN pyramids in this work can be used as a high-quality template for optoelectronic devices having indium-rich active layers, with a potential of reaching green, yellow, and red emissions for LEDs.
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| 50. |
- Bi, Zhaoxia, et al.
(författare)
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InGaN Platelets : Synthesis and Applications toward Green and Red Light-Emitting Diodes
- 2019
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Ingår i: Nano Letters. - : American Chemical Society. - 1530-6984 .- 1530-6992. ; 19:5, s. 2832-2839
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we present a method to synthesize arrays of hexagonal InGaN submicrometer platelets with a top c-plane area having an extension of a few hundred nanometers by selective area metal-organic vapor-phase epitaxy. The InGaN platelets were made by in situ annealing of InGaN pyramids, whereby InGaN from the pyramid apex was thermally etched away, leaving a c-plane surface, while the inclined {101Ì1} planes of the pyramids were intact. The as-formed c-planes, which are rough with islands of a few tens of nanometers, can be flattened with InGaN regrowth, showing single bilayer steps and high-quality optical properties (full width at half-maximum of photoluminescence at room temperature: 107 meV for In 0.09 Ga 0.91 N and 151 meV for In 0.18 Ga 0.82 N). Such platelets offer surfaces having relaxed lattice constants, thus enabling shifting the quantum well emission from blue (as when grown on GaN) to green and red. For single InGaN quantum wells grown on the c-plane of such InGaN platelets, a sharp interface between the quantum well and the barriers was observed. The emission energy from the quantum well, grown under the same conditions, was shifted from 2.17 eV on In 0.09 Ga 0.91 N platelets to 1.95 eV on In 0.18 Ga 0.82 N platelets as a result of a thicker quantum well and a reduced indium pulling effect on In 0.18 Ga 0.82 N platelets. On the basis of this method, prototype light-emitting diodes were demonstrated with green emission on In 0.09 Ga 0.91 N platelets and red emission on In 0.18 Ga 0.82 N platelets.
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