| 1. |
- Ekström, Andreas, 1980, et al.
(författare)
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Bayesian optimization in ab initio nuclear physics
- 2019
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Ingår i: Journal of Physics G-Nuclear and Particle Physics. - : IOP Publishing. - 0954-3899 .- 1361-6471. ; 46:9
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Tidskriftsartikel (refereegranskat)abstract
- Theoretical models of the strong nuclear interaction contain unknown coupling constants (parameters) that must be determined using a pool of calibration data. In cases where the models are complex, leading to time consuming calculations, it is particularly challenging to systematically search the corresponding parameter domain for the best fit to the data. In this paper, we explore the prospect of applying Bayesian optimization to constrain the coupling constants in chiral effective field theory descriptions of the nuclear interaction. We find that Bayesian optimization performs rather well with low-dimensional parameter domains and foresee that it can be particularly useful for optimization of a smaller set of coupling constants. A specific example could be the determination of leading three-nucleon forces using data from finite nuclei or three-nucleon scattering experiments.
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| 2. |
- Ekström, Andreas, 1979, et al.
(författare)
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Can't beat the heat? Importance of cardiac control and coronary perfusion for heat tolerance in rainbow trout
- 2019
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Ingår i: Journal of Comparative Physiology B-Biochemical Systems and Environmental Physiology. - : Springer Science and Business Media LLC. - 0174-1578 .- 1432-136X. ; 189, s. 757-769
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Tidskriftsartikel (refereegranskat)abstract
- Coronary perfusion and cardiac autonomic regulation may benefit myocardial oxygen delivery and thermal performance of the teleost heart, and thus influence whole animal heat tolerance. Yet, no study has examined how coronary perfusion affects cardiac output during warming in vivo. Moreover, while beta-adrenergic stimulation could protect cardiac contractility, and cholinergic decrease in heart rate may enhance myocardial oxygen diffusion at critically high temperatures, previous studies in rainbow trout (Oncorhynchus mykiss) using pharmacological antagonists to block cholinergic and beta-adrenergic regulation showed contradictory results with regard to cardiac performance and heat tolerance. This could reflect intra-specific differences in the extent to which altered coronary perfusion buffered potential negative effects of the pharmacological blockade. Here, we first tested how cardiac performance and the critical thermal maximum (CTmax) were affected following a coronary ligation. We then assessed how these performances were influenced by pharmacological cholinergic or beta-adrenergic blockade, hypothesising that the effects of the pharmacological treatment would be more pronounced in coronary ligated trout compared to trout with intact coronaries. Coronary blockade reduced CTmax by 1.5 degrees C, constrained stroke volume and cardiac output across temperatures, led to earlier cardiac failure and was associated with reduced blood oxygen-carrying capacity. Nonetheless, CTmax and the temperatures for cardiac failure were not affected by autonomic blockade. Collectively, our data show that coronary perfusion improves heat tolerance and cardiac performance in trout, while evidence for beneficial effects of altered cardiac autonomic tone during warming remains inconclusive.
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| 3. |
- Morgenroth, Daniel, et al.
(författare)
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Hemodynamic responses to warming in euryhaline rainbow trout: implications of the osmo-respiratory compromise
- 2019
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Ingår i: Journal of Experimental Biology. - : The Company of Biologists. - 0022-0949 .- 1477-9145. ; 222:17
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Tidskriftsartikel (refereegranskat)abstract
- In seawater, rainbow trout (Oncorhynchus mykiss) drink and absorb water through the gastrointestinal tract to compensate for water passively lost to the hyperosmotic environment. Concomitantly, they exhibit elevated cardiac output and a doubling of gastrointestinal blood flow to provide additional O-2 to the gut and increase convective flux of absorbed ions and water. Yet, it is unknown how warming waters, which elevate tissue O-2 demand and the rate of diffusion of ions and water across the gills (i.e. the osmo-respiratory compromise), affects these processes. We measured cardiovascular and blood variables of rainbow trout acclimated to freshwater and seawater during acute warming from 11 to 17 degrees C. Relative to freshwater-acclimated trout, cardiac output was 34% and 55% higher in seawater-acclimated trout at 11 and 17 degrees C, respectively, which allowed them to increase gastrointestinal blood flow significantly more during warming (increases of 75% in seawater vs. 31% in freshwater). These adjustments likely served to mitigate the impact of warming on osmotic balance, as changes in ionic and osmotic blood composition were minor. Furthermore, seawater-acclimated trout seemingly had a lower tissue O-2 extraction, explaining why trout acclimated to freshwater and seawater often exhibit similar metabolic rates, despite a higher cardiac output in seawater. Our results highlight a novel role of gastrointestinal blood perfusion in the osmo-respiratory compromise in fish, and improve our understanding of the physiological changes euryhaline fishes must undergo when faced with interacting environmental challenges such as transient warming events.
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| 4. |
- Pichaud, Nicolas, 1978, et al.
(författare)
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Cardiac mitochondrial plasticity and thermal sensitivity in a fish inhabiting an artificially heated ecosystem
- 2019
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Ingår i: Scientific Reports. - : Springer Science and Business Media LLC. - 2045-2322. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Some evidence suggests that cardiac mitochondrial functions might be involved in the resilience of ectotherms such as fish to environmental warming. Here, we investigated the effects of acute and chronic changes in thermal regimes on cardiac mitochondrial plasticity and thermal sensitivity in perch (Perca fluviatilis) from an artificially heated ecosystem; the "Biotest enclosure" (similar to 25 degrees C), and from an adjacent area in the Baltic Sea with normal temperatures (reference, similar to 16 degrees C). We evaluated cardiac mitochondrial respiration at assay temperatures of 16 and 25 degrees C, as well as activities of lactate dehydrogenase (LDH) and citrate synthase (CS) in Biotest and reference perch following 8 months laboratory-acclimation to either 16 or 25 degrees C. While both populations exhibited higher acute mitochondrial thermal sensitivity when acclimated to their natural habitat temperatures, this sensitivity was lost when Biotest and reference fish were acclimated to 16 and 25 degrees C, respectively. Moreover, reference fish displayed patterns of metabolic thermal compensation when acclimated to 25 degrees C, whereas no changes were observed in Biotest perch acclimated to 16 degrees C, suggesting that cardiac mitochondrial metabolism of Biotest fish expresses local adaptation. This study highlights the adaptive responses of cardiac mitochondria to environmental warming, which can impact on fish survival and distribution in a warming climate.
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| 5. |
- Wallerius, Magnus L., et al.
(författare)
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Socially induced stress and behavioural inhibition in response to angling exposure in rainbow trout
- 2019
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Ingår i: Fisheries Management and Ecology. - : Wiley. - 0969-997X .- 1365-2400. ; 26:6, s. 611-620
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that fish can learn to avoid angling gear after experiencing a catch-and-release event, that is, after a private hooking experience. However, the possible importance of social information cues and their influence on an individual's vulnerability to angling remains largely unexplored, that is, social experience of a conspecific capture. The effects of private and social experience of hooking on the stress response of fish and subsequent catch rates were examined. Hatchery-reared rainbow trout, Oncorhynchus mykiss (Walbaum), were implanted with heart rate loggers and experimentally subjected to private or social experience of hooking. Private and social experience of angling induced an increased heart rate in fish compared with naive control fish. While private experience of hooking explained most of the reduced vulnerability to capture, no clear evidence was found that social experience of hooking affected angling vulnerability in fish that had never been hooked before. While both private and social experiences of angling constitute significant physiological stressors for rainbow trout, only the private experience reduces an individual's vulnerability to angling and in turn affecting population-level catchability.
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