| 1. |
- Jonsson, Per R., 1957, et al.
(författare)
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Making water flow: a comparison of the hydrodynamic characteristics of 12 different benthic biological flumes
- 2006
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Ingår i: Aquatic Ecology. - : Springer Science and Business Media LLC. - 1386-2588 .- 1573-5125. ; 40:4, s. 409-438
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Tidskriftsartikel (refereegranskat)abstract
- Flume tanks are becoming increasingly important research tools in aquatic ecology, to link biological to hydrodynamical processes. There is no such thing as a "standard flume tank", and no flume tank is suitable for every type of research question. A series of experiments has been carried out to characterise and compare the hydrodynamic characteristics of 12 different flume tanks that are designed specifically for biological research. These facilities are part of the EU network BioFlow. The flumes could be divided into four basic design types: straight, racetrack, annular and field flumes. In each facility, two vertical velocity profiles were measured: one at 0.05 m s(-1) and one at 0.25 m s(-1). In those flumes equipped with Acoustic Doppler Velocimeters (ADV), time series were also recorded for each velocity at two heights above the bottom: 0.05 m and 20% of the water depth. From these measurements turbulence characteristics, such as TKE and Reynolds stress, were derived, and autocorrelation spectra of the horizontal along-stream velocity component were plotted. The flume measurements were compared to two sets of velocity profiles measured in the field. Despite the fact that some flumes were relatively small, turbulence was fully developed in all channels. Straight and racetrack flumes generally produced boundary layers with a clearly definable logarithmic layer, similar to measurements in the field taken under steady flow conditions. The two annular flumes produced relatively thin boundary layers, presumably due to secondary flows developing in the curved channels. The profiles in the field flumes also differed considerably from the expected log profile. This may either have been due the construction of the flume, or due to unsteady conditions during measurement. Constraints imposed by the different flume designs on the suitability for different types of boundary layer research, as well as scaling issues are discussed.
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| 2. |
- van Der Heijden, L. H., et al.
(författare)
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Quantitative food web modeling unravels the importance of the microphytobenthos-meiofauna pathway for a high trophic transfer by meiofauna in soft-bottom intertidal food webs
- 2020
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Ingår i: Ecological Modelling. - : Elsevier BV. - 0304-3800. ; 430
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Tidskriftsartikel (refereegranskat)abstract
- Meiofauna are known to have an important role on many ecological processes, although, their role in food web dynamics is often poorly understood, partially as they have been an overlooked and under sampled organism group. Here, we used quantitative food web modeling to evaluate the trophic relationship between meiofauna and their food sources and how meiofauna can mediate the carbon flow to higher trophic levels in five contrasting soft-bottom intertidal habitats (including seagrass beds, mudflats and sandflats). Carbon flow networks were constructed using the linear inverse model-Markov chain Monte Carlo technique, with increased resolution of the meiofauna compartments (i.e. biomass and feeding ecology of the different trophic groups of meiofauna) compared to most previous modeling studies. These models highlighted that the flows between the highly productive microphytobenthos and the meiofauna compartments play an important role in transferring carbon to the higher trophic levels, typically more efficiently so than macrofauna. The pathway from microphytobenthos to meiofauna represented the largest flow in all habitats and resulted in high production of meiofauna independent of habitat. All trophic groups of meiofauna, except for selective deposit feeders, had a very high dependency on microphytobenthos. Selective deposit feeders relied instead on a wider range of food sources, with varying contributions of bacteria, microphytobenthos and sediment organic matter. Ecological network analyses (e.g. cycling, throughput and ascendency) of the modeled systems highlighted the close positive relationship between the food web efficiency and the assimilation of high-quality food sources by primary consumers, e.g. meiofauna and macrofauna. Large proportions of these flows can be attributed to trophic groups of meiofauna. The sensitivity of the network properties to the representation of meiofauna in the models leads to recommending a greater attention in ecological data monitoring and integrating meiofauna into food web models.
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| 3. |
- Li, Jun, et al.
(författare)
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ALPPS for Locally Advanced Intrahepatic Cholangiocarcinoma: Did Aggressive Surgery Lead to the Oncological Benefit? An International Multi-center Study
- 2020
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Ingår i: Annals of Surgical Oncology. - : SPRINGER. - 1068-9265 .- 1534-4681. ; 27, s. 1372-1384
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Tidskriftsartikel (refereegranskat)abstract
- Background ALPPS is found to increase the resectability of primary and secondary liver malignancy at the advanced stage. The aim of the study was to verify the surgical and oncological outcome of ALPPS for intrahepatic cholangiocarcinoma (ICC). Methods The study cohort was based on the ALPPS registry with patients from 31 international centers between August 2009 and January 2018. Propensity score matched patients receiving chemotherapy only were selected from the SEER database as controls for the survival analysis. Results One hundred and two patients undergoing ALPPS were recruited, 99 completed the second stage with median inter-stage duration of 11 days. The median kinetic growth rate was 23 ml/day. R0 resection was achieved in 87 (85%). Initially high rates of morbidity and mortality decreased steadily to a 29% severe complication rate and 7% 90-day morbidity in the last 2 years. Post-hepatectomy liver failure remained the main cause of 90-day mortality. Multivariate analysis revealed insufficient future liver remnant at the stage-2 operation (FLR2) to be the only risk factor for severe complications (OR 2.91, p = 0.02). The propensity score matching analysis showed a superior overall survival in the ALPPS group compared to palliative chemotherapy (median overall survival: 26.4 months vs 14 months; 1-, 2-, and 3-year survival rates: 82.4%, 70.5% and 39.6% vs 51.2%, 21.4% and 11.3%, respectively, p amp;lt; 0.01). The survival benefit, however, was not confirmed in the subgroup analysis for patients with insufficient FLR2 or multifocal ICC. Conclusion ALPPS showed high efficacy in achieving R0 resections in locally advanced ICC. To get the most oncological benefit from this aggressive surgery, ALPPS would be restricted to patients with single lesions and sufficient FLR2.
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| 4. |
- Panman, Matthijs R, 1983, et al.
(författare)
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Observing the Structural Evolution in the Photodissociation of Diiodomethane with Femtosecond Solution X-Ray Scattering
- 2020
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 125:22
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Tidskriftsartikel (refereegranskat)abstract
- Resolving the structural dynamics of the initial steps of chemical reactions is challenging. We report the femtosecond time-resolved wide-angle x-ray scattering of the photodissociation of diiodomethane in cyclohexane. The data reveal with structural detail how the molecule dissociates into radicals, how the radicals collide with the solvent, and how they form the photoisomer. We extract how translational and rotational kinetic energy is dispersed into the solvent. We also find that 85% of the primary radical pairs are confined to their original solvent cage and discuss how this influences the downstream recombination reactions.
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