| 1. |
- Wulff, Angela, 1963, et al.
(författare)
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UV radiation - a threat to Antarctic benthic marine diatoms?
- 2008
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Ingår i: Antarctic Science. - 0954-1020. ; 20:1, s. 13-20
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Tidskriftsartikel (refereegranskat)abstract
- This investigation was motivated by the lack of ultraviolet radiation (UVR, 280-400 nm) studies on Antarctic benthic marine microalgae. The objective was to estimate the impact of UV-B (280-315 nm) and UV-A (315-400 nm), on photosynthetic efficiency, species composition, cell density and specific growth rate in a semi-natural soft-bottom diatom community. In both experiments, cell density increased over time. The most frequently observed species were Navicula cancellata, Cylindrotheca closterium, Nitzschia spp., and Petroneis plagiostoma. For both experiments, a shift in species composition and a decreased photosystem II (PSII) maximum efficiency (F-v/F-m) over time was observed, irrespective of treatment. UVR significantly reduced F-v/F-m on days 3 and 10 (Expt 1), disappearing on the last sampling date. A similar trend was found in Expt 2. A significant UV effect on cell density was observed in Expt 1 (day 10) but not in Expt 2. No treatment effects on species composition or specific growth rate were found. Thus, the UV effects were transient (photosynthetic efficiency and cell density) and the growth of the benthic diatoms was generally unaffected. Overall, according to our results, UVR does not seem to be a threat to benthic marine Antarctic diatoms.
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| 3. |
- Dmytryshyn, Andrii, 1986-, et al.
(författare)
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Skew-symmetric matrix pencils : codimension counts and the solution of a pair of matrix equations
- 2013
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Ingår i: Linear Algebra and its Applications. - : Elsevier. - 0024-3795 .- 1873-1856. ; 438:8, s. 3375-3396
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Tidskriftsartikel (refereegranskat)abstract
- The homogeneous system of matrix equations (X(T)A + AX, (XB)-B-T + BX) = (0, 0), where (A, B) is a pair of skew-symmetric matrices of the same size is considered: we establish the general solution and calculate the codimension of the orbit of (A, B) under congruence. These results will be useful in the development of the stratification theory for orbits of skew-symmetric matrix pencils.
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| 4. |
- Gorokhova, Elena, et al.
(författare)
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How Copepods Can Eat Toxins Without Getting Sick : Gut Bacteria Help Zooplankton to Feed in Cyanobacteria Blooms
- 2021
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Ingår i: Frontiers in Microbiology. - : Frontiers Media SA. - 1664-302X. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Toxin-producing cyanobacteria can be harmful to aquatic biota, although some grazers utilize them with often beneficial effects on their growth and reproduction. It is commonly assumed that gut microbiota facilitates host adaptation to the diet; however, the evidence for adaptation mechanisms is scarce. Here, we investigated the abundance of mlrA genes in the gut of the Baltic copepods Acartia bifilosa and Eurytemora affinis during cyanobacteria bloom season (August) and outside it (February). The mlrA genes are unique to microcystin and nodularin degraders, thus indicating the capacity to break down these toxins by the microbiota. The mlrA genes were expressed in the copepod gut year-round, being >10-fold higher in the summer than in the winter populations. Moreover, they were significantly more abundant in Eurytemora than Acartia. To understand the ecological implications of this variability, we conducted feeding experiments using summer- and winter-collected copepods to examine if/how the mlrA abundance in the microbiota affect: (1) uptake of toxic Nodularia spumigena, (2) uptake of a non-toxic algal food offered in mixtures with N. spumigena, and (3) concomitant growth potential in the copepods. The findings provide empirical evidence that the occurrence of mlrA genes in the copepod microbiome facilitates nutrient uptake and growth when feeding on phytoplankton mixtures containing nodularin-producing cyanobacteria; thus, providing an adaptation mechanism to the cyanobacteria blooms.
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| 5. |
- Katawazai, Asmatullah, MD, PhD student, 1977-, et al.
(författare)
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RISK OF VENTRAL HERNIAS IN RELATION TO PARITY IN WOMEN, A POPULATION-BASED STUDY
- 2024
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Ingår i: British Journal of Surgery. - : Oxford University Press. - 0007-1323 .- 1365-2168. ; 111:Suppl. 5
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Introduction: The influence of pregnancy on the risk of ventral hernia recurrence is not known. This study aims to assess whether the frequency of pregnancies is associated with an elevated risk of developing ventral hernias.Method: This nationwide study cohort constitutes women borne 1950 – who were registered in the Swedish Birth Register (MBR). Data on pregnancies, distinguishing between vaginal and caesarian sections, were retrieved from the Birth Register. The cohort was cross-matched with the National Patient Register (NPR) to identify subsequent primary hernia repairs.Results: A total of 1,630,754 women born between 1950 and 1980 were included in the study. Among them, 1,588,609 (92.3%) were registered for at least one birth. The incidence rate for Umbilical Hernia Repair (UHR) and Epigastric Hernia Repair (EHR) was 13.21 per 100,000 person-years and 5.4 per 100,000 person-years, respectively. When compared with women registered for one delivery, the incidence rate ratio for UHR was 1.3 (95% CI: 1.26–1.33, P < 0.001) among thos eregistered for two deliveries and 1.6 (95% CI: 1.58–1.68, P < 0.001) among those registered for ≥3 deliveries.The incidence rate ratios were 1.29 (95% CI: 1.20–1.39, P < 0.001) and 1.34 (95% CI: 1.24–1.45, P < 0.001) for EHR among women with two and ≥3 registered deliveries, respectively.Conclusion: A history of more than one pregnancy is associated with an increased incidence of umbilical and epigastric hernias.
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| 8. |
- Willander, Erika, 1978-, et al.
(författare)
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Ett första spadtag för statistik över diakoni
- 2015
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Ingår i: Nyckeln till Svenska kyrkan. - Uppsala : Svenska kyrkan. - 1651-0755. ; , s. 43-51
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Tidskriftsartikel (populärvet., debatt m.m.)
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| 10. |
- Chambault, Philippine, et al.
(författare)
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The influence of oceanographic features on the foraging behavior of the olive ridley sea turtle Lepidochelys olivacea along the Guiana coast
- 2016
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Ingår i: Progress in Oceanography. - : Elsevier BV. - 0079-6611 .- 1873-4472. ; 142, s. 58-71
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Forskningsöversikt (refereegranskat)abstract
- The circulation in the Western Equatorial Atlantic is characterized by a highly dynamic mesoscale activity that shapes the Guiana continental shelf. Olive ridley sea turtles (Lepidochelys olivacea) nesting in French Guiana cross this turbulent environment during their post-nesting migration. We studied how oceanographic and biological conditions drove the foraging behavior of 18 adult females, using satellite telemetry, remote sensing data (sea surface temperature, sea surface height, current velocity and euphotic depth), simulations of micronekton biomass (pelagic organisms) and in situ records (water temperature and salinity). The occurrence of foraging events throughout migration was located using Residence Time analysis, while an innovative proxy of the hunting time within a dive was used to identify and quantify foraging events during dives. Olive ridleys migrated northwestwards using the Guiana current and remained on the continental shelf at the edge of eddies formed by the North Brazil retroflection, an area characterized by low turbulence and high micronekton biomass. They performed mainly pelagic dives, hunting for an average 77% of their time. Hunting time within a dive increased with shallower euphotic depth and with lower water temperatures, and mean hunting depth increased with deeper thermocline. This is the first study to quantify foraging activity within dives in olive ridleys, and reveals the crucial role played by the thermocline on the foraging behavior of this carnivorous species. This study also provides novel and detailed data describing how turtles actively use oceanographic structures during post-nesting migration.
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