| 1. |
- Belle, Simon
(författare)
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Reconstruction of Past Dynamics of Methane-Oxidizing Bacteria in Lake Sediments Using a Quantitative PCR Method: Connecting Past Environmental Changes and Microbial Community
- 2019
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Ingår i: Geomicrobiology Journal. - : Informa UK Limited. - 0149-0451 .- 1521-0529. ; 36, s. 570-579
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a quantitative PCR (qPCR) method was applied to amplify ancient DNA (aDNA) of different methane-oxidizing bacteria (MOB) types in lake sediments and to reconstruct microbial community dynamics over the last 1200 years. We also used reconstructions of in-lake nutrients concentrations, air temperature fluctuations, and sedimentary organic matter dynamics to study impacts of past environmental and climatic changes on MOB community composition. DNA preservation in lake sediments is sufficient, and qPCR amplification was successfully applied to the analysis of MOB aDNA. Temporal changes in MOB community showed different patterns between lakes, and drivers of past MOB dynamics slightly differed between lakes and among MOB groups. Overall, MOB developments were generally correlated to proxies of organic matter quality/quantity and climate data. Moreover, our results could emphasize the importance of nutrients availability in structuring MOB community, and the higher ability of MOB type 2 to access nutrients under nitrogen/nutrients limited conditions. Therefore, our study provides an operational and time-effective method to reconstruct past CH4 oxidation in lakes and could help to identify the driving factors of past temporal dynamics of MOB community.
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| 2. |
- Belle, Simon, et al.
(författare)
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Unravelling chironomid biodiversity response to climate change in subarctic lakes across temporal and spatial scales
- 2022
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Ingår i: Hydrobiologia. - : Springer Science and Business Media LLC. - 0018-8158 .- 1573-5117. ; 849, s. 2621-2633
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Tidskriftsartikel (refereegranskat)abstract
- We combined paleolimnological reconstructions and space-for-time substitutions to unravel chironomid biodiversity responses to climate change in subarctic mountains across temporal and spatial scales. Using sediment records, we found that long-term temporal changes in chironomid taxonomic diversity were mainly induced by the temperature tolerance/optimum of species, while little changes in functional diversity were found due to the replacement of similar functional-type taxa within the community. Overall, paleolimnological reconstructions suggested the selection of larger chironomid species by long-term climate cooling and little changes in trophic guilds. Space-for-time substitutions showed, however that low-elevation lakes with forested have more sediment-feeding taxa and larger larvae than high-elevation lakes, thus, suggesting the selection of large chironomid morphotypes with a sediment-feeding mode under warmer climate. Space-for-time substitutions and paleolimnological reconstructions, therefore, gave contrasting results for the link between climate and functional diversity of chironomid communities, likely because space-for-time substitutions failed to match the extent of both spatial and temporal climatic gradients. We suggest that future studies must address biodiversity issues across both temporal and spatial scales as an improved understanding of biodiversity responses to climate change may help us to understand how biodiversity will be affected by ongoing and future change.
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| 3. |
- de Ridder, Adri, et al.
(författare)
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Managerial actions and nominal stock price levels
- 2016
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Ingår i: European Journal of Finance. - 1351-847X .- 1466-4364. ; 22:14, s. 1435-1456
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Tidskriftsartikel (refereegranskat)abstract
- We examine nominal and real stock prices and the sequential price pattern of stock dividends and stock splits. We find that the average stock price has been fairly stable over time except for two decades in the beginning and end of the twentieth century. Inclusion of these periods yield a decline over time which is generally consistent with the drop in price levels found by Chittenden et al. [2010. A Note on Affordability and the Optimal Share Price. Financial Review 45: 205-216]. In a multivariate setting, the frequency of stock dividends and stock splits is positively related to the frequency for these events the prior year and recent market return. In further tests of the price change we find a positive relationship to the median price change for stock dividends/splits and negatively to labour income growth for stock splits. These findings indicate that stock price reduction via stock dividends and splits attracts individual investors as income grows. One key conclusion is that the primary reason for any stock action, dividend or split, is to fit the norm' stock price level of the market.
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| 4. |
- de Ridder, Adri, et al.
(författare)
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Institutional investors' holdings surrounding equity rights offerings
- 2012
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Ingår i: Global Finance Journal. - : Elsevier BV. - 1044-0283 .- 1873-5665. ; 23:2, s. 125-140
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Tidskriftsartikel (refereegranskat)abstract
- We examine shareholding surrounding Swedish rights offerings using detailed information on the ownership in firms. We analyze shareholding levels and their changes for domestic and foreign institutional investors. As institutional holdings change, domestic institutions increase their holdings more than foreign institutions. Our examination of low and high buying activities by institutional investors surrounding rights offerings shows no stock picking ability, thus not supporting the "smart-money hypothesis" (Gibson et al., 2004). We also find that investor domicile influences firm value following the offering. Overall, foreign investors exhibit a strong and opposite directional reaction to adverse selection costs than domestic investors.
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| 5. |
- Mullier, G.A., et al.
(författare)
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Constraints on spin-0 dark matter mediators and invisible Higgs decays using ATLAS 13 TeV pp collision data with two top quarks and missing transverse momentum in the final state
- 2023
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Ingår i: European Physical Journal C. - : Institute for Ionics. - 1434-6044 .- 1434-6052. ; 83:6
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Tidskriftsartikel (refereegranskat)abstract
- This paper presents a statistical combination of searches targeting final states with two top quarks and invisible particles, characterised by the presence of zero, one or two leptons, at least one jet originating from a b-quark and missing transverse momentum. The analyses are searches for phenomena beyond the Standard Model consistent with the direct production of dark matter in pp collisions at the LHC, using 139 fb−1 of data collected with the ATLAS detector at a centre-of-mass energy of 13 TeV. The results are interpreted in terms of simplified dark matter models with a spin-0 scalar or pseudoscalar mediator particle. In addition, the results are interpreted in terms of upper limits on the Higgs boson invisible branching ratio, where the Higgs boson is produced according to the Standard Model in association with a pair of top quarks. For scalar (pseudoscalar) dark matter models, with all couplings set to unity, the statistical combination extends the mass range excluded by the best of the individual channels by 50 (25) GeV, excluding mediator masses up to 370 GeV. In addition, the statistical combination improves the expected coupling exclusion reach by 14% (24%), assuming a scalar (pseudoscalar) mediator mass of 10 GeV. An upper limit on the Higgs boson invisible branching ratio of 0.38 () is observed (expected) at 95% confidence level.
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| 7. |
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| 8. |
- Trouw, Leendert, et al.
(författare)
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C4b-binding protein and factor h compensate for the loss of membrane-bound complement inhibitors to protect apoptotic cells against excessive complement attack
- 2007
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Ingår i: Journal of Biological Chemistry. - 1083-351X. ; 282:39, s. 28540-28548
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Tidskriftsartikel (refereegranskat)abstract
- Apoptotic cells have been reported to down- regulate membrane-bound complement regulatory proteins ( m- C- Reg) and to activate complement. Nonetheless, most apoptotic cells do not undergo complement- mediated lysis. Therefore, we hypothesized that fluid phase complement inhibitors would bind to apoptotic cells and compensate functionally for the loss of m- C- Reg. We observed that m- C- Reg are down- regulated rapidly upon apoptosis but that complement activation follows only after a gap of several hours. Coinciding with, but independent from, complement activation, fluid phase complement inhibitors C4b- binding protein ( C4BP) and factorH( fH) bind to the cells. C4BP and fH do not entirely prevent complement activation but strongly limit C3 and C9 deposition. Late apoptotic cells, present in blood of healthy controls and systemic lupus erythematosus patients, are also positive for C4BP and fH. Upon culture, the percentage of late apoptotic cells increases, paralleled by increased C4BP binding. C4BP binds to dead cells mainly via phosphatidylserine, whereas fH binds via multiple interactions with CRP playing no major role for binding of C4BP or fH. In conclusion, during late apoptosis, cells acquire fluid phase complement inhibitors that compensate for the downregulation of m- C- Reg and protect against excessive complement activation and lysis.
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| 9. |
- Walters, Jamie, et al.
(författare)
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A Relational Context Proximity Query Language
- 2015
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Ingår i: Mobile Networks and Management. - Berlin : Springer. - 9783319162911 - 9783319162928 ; , s. 277-289
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Konferensbidrag (refereegranskat)abstract
- The creation of applications and services realising massive immersive participation require the provisioning of current, relevant and accurate context information. These applications benefit from access to this highly dynamic information in real time. Existing approaches to provisioning context information are limited by their interpretation of context relationships as address book solutions thus limiting the discovering of related entities. We introduce the context proximity query language (CPQL) for querying context related entities on distributed across collections of remote endpoints. As a declarative query language (CPQL) is similar in structure to SQL and describes the relationships between entities as distance functions between their associated context information. We simulate CPQL and show that it offers improvements over existing approaches while scaling well.
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| 10. |
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