| 1. |
- Möller, Peter, et al.
(författare)
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Detailed modeling of odd–even staggering in fission-fragment charge distributions : Damping of staggering effects with excitation energy and compound-nucleus charge
- 2024
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Ingår i: European Physical Journal A. - 1434-6001. ; 60:2
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Tidskriftsartikel (refereegranskat)abstract
- During the last 10 years or so the Brownian shape-motion (BSM) model has been used in numerous calculations of fission-fragment mass and charge distributions with encouraging agreement with experimental measurements. In this model the structure obtained in the fission-fragment distributions is entirely a consequence of the structures in the calculated five-dimensional (5D) potential-energy surfaces. The potential-energy model until recently did not accommodate the influence of the emerging fragment properties on the calculated potential energy. Therefore there were no odd-even effects in the calculated fission-fragment distributions. Recent extensions of the potential-energy model allow properties of the nascent fragments to be included in the potential-energy model. Application of the BSM model to execute random walks on these more detailed potential-energy surfaces led to calculated fission-fragment yields that exhibited odd-even effects, which “by eye” indicated reasonable agreement with experimental data. The present work goes a step further with a quantitative comparison between experimental and theoretical results based on the global and local odd-even staggering observables. Theoretical calculations and experimental observations both show that pairing effects and enhancement of two-nucleon relative to one-nucleon transfer in heavy-ion collisions decrease with excitation energy and implementing a damping of these quantities with excitation energy leads to improved agreement with experiment. Characteristic variations of the local staggering with charge split seen in the experimental data are also present in the calculated results.
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| 2. |
- Möller, Peter
(författare)
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The most important theoretical developments leading to the current understanding of heavy-element stability : With some personal recollections from the past 55 years (1965–2020)
- 2023
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Ingår i: European Physical Journal A. - 1434-6001. ; 59:4
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Forskningsöversikt (refereegranskat)abstract
- We discuss the sequence of developments that over the past 90 years led to current insights on heavy-element stability. The semi-empirical mass model, and its extension to deformed shapes, developed in the period 1936–1950 allowed the interpretation of nuclear fission. Around 1950 the spherical single-particle model was developed, soon after with extension to deformed nuclei. Speculations about a shell-stabilized region of spherical heavy elements near Z= 126 were made. In the 1960ies Strutinsky combined the single-particle and macroscopic liquid-drop models into a unified picture, the shell-correction, or macroscopic-microscopic method. Now it was also realized that although Z= 126 was present, an often stronger spherical gap in calculated proton single-particle level diagrams, Z= 114 , was also present, but its significance had previously been overlooked. A large number of studies of the stability of nuclei in the “shell-stabilized” region surrounding Z= 114 and N= 184 followed. Initially the assumption was that elements just beyond the actinides, would be too unstable to be observed. The 1970ies saw considerable work in refining the initial single-particle and macroscopic models. This set the stage for global studies, which took off in the 1980ies and have continued until today. The more accurate nuclear-structure models allowed calculations of masses, decay-chain properties and branching between different decay modes to useful accuracy and predictive quality. A completely unexpected result was that the calculations showed the existence of an area of relatively stable deformed nuclei in the presumed “sea of instability” between the actinides and the next postulated spherical magic numbers.
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| 3. |
- Rothmann, Monika Hezareh, et al.
(författare)
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Genotoxicity by rapeseed methyl ester and hydrogenated vegetable oil combustion exhaust products in lung epithelial (A549) cells
- 2023
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Ingår i: Mutagenesis. - 0267-8357. ; 38:4, s. 238-249
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Tidskriftsartikel (refereegranskat)abstract
- Biofuel is an attractive substitute for petrodiesel because of its lower environmental footprint. For instance, the polycyclic aromatic hydrocarbons (PAH) emission per fuel energy content is lower for rapeseed methyl ester (RME) than for petrodiesel. The present study assesses genotoxicity by extractable organic matter (EOM) of exhaust particles from combustion of petrodiesel, RME and hydrogenated vegetable oil (HVO) in lung epithelial (A549) cells. Genotoxicity was assessed as DNA strand breaks by the alkaline comet assay. EOM from combustion of petrodiesel and RME generated the same level of DNA strand breaks based on equal concentration of total PAH (i.e. net increases of 0.13 [95% confidence interval (CI): 0.002, 0.259 and 0.12 [95% CI: 0.01, 0.24] lesions per million base pairs, respectively). In comparison, the positive control (etoposide) generated much higher level of DNA strand breaks (i.e. 0.84, 95% CI: 0.72, 0.97) lesions per million base pairs). Relatively low concentrations of EOM from RME and HVO combustion particles (<116 ng/ml total PAH) did not cause DNA strand breaks in A549 cells, whereas benzo[a]pyrene and PAH-rich EOM from petrodiesel combusted using low oxygen inlet concentration were genotoxic. The genotoxicity was attributed to high molecular weight PAH isomers with 5-6 rings. In summary, the results show that EOM from combustion of petrodiesel and RME generate the same level of DNA strand breaks on equal total PAH basis. However, the genotoxic hazard of engine exhaust from on-road vehicles is lower for RME than petrodiesel because of lower PAH emission per fuel energy content.
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| 4. |
- Scholten, Rebecca Harnung, et al.
(författare)
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Inhalation of hydrogenated vegetable oil combustion exhaust and genotoxicity responses in humans
- 2021
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Ingår i: Archives of Toxicology. - : Springer Science and Business Media LLC. - 0340-5761 .- 1432-0738. ; 95:10, s. 3407-3416
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Tidskriftsartikel (refereegranskat)abstract
- Biofuels from vegetable oils or animal fats are considered to be more sustainable than petroleum-derived diesel fuel. In this study, we have assessed the effect of hydrogenated vegetable oil (HVO) exhaust on levels of DNA damage in peripheral blood mononuclear cells (PBMCs) as primary outcome, and oxidative stress and inflammation as mediators of genotoxicity. In a randomized cross-over study, healthy humans were exposed to filtered air, inorganic salt particles, exhausts from combustion of HVO in engines with aftertreatment [i.e. emission with nitrogen oxides and low amounts of particulate matter less than 2.5 µm (approximately 1 µg/m3)], or without aftertreatment (i.e. emission with nitrogen oxides and 93 ± 13 µg/m3 of PM2.5). The subjects were exposed for 3 h and blood samples were collected before, within 1 h after the exposure and 24 h after. None of the exposures caused generation of DNA strand breaks and oxidatively damaged DNA, or affected gene expression of factors related to DNA repair (Ogg1), antioxidant defense (Hmox1) or pro-inflammatory cytokines (Ccl2, Il8 and Tnfa) in PBMCs. The results from this study indicate that short-term HVO exhaust exposure is not associated with genotoxic hazard in humans.
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| 5. |
- Albertsson, Martin, et al.
(författare)
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Calculated fission-fragment mass yields and average total kinetic energies of heavy and superheavy nuclei
- 2020
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Ingår i: European Physical Journal A. - : Springer Science and Business Media LLC. - 1434-6001 .- 1434-601X. ; 56:2
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Tidskriftsartikel (refereegranskat)abstract
- Fission-fragment mass and total-kinetic-energy (TKE) distributions following fission of even-even nuclides in the region 74 ≤ Z≤ 126 and 92 ≤ N≤ 230 , comprising 896 nuclides have been calculated using the Brownian shape-motion method. The emphasis is the region of superheavy nuclei. To show compatibility with earlier results the calculations are extended to include earlier studied regions. An island of asymmetric fission is obtained in the superheavy region, 106 ≤ Z≤ 114 and 162 ≤ N≤ 176 , where the heavy fragment is found to be close to 208Pb and the light fragment adjusts accordingly. Most experimentally observed α-decay chains of superheavy nuclei with Z> 113 terminate by spontaneous fission in our predicted region of asymmetric fission. In these cases, the pronounced large asymmetry is accompanied by a low TKE value compatible with measurements.
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| 6. |
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| 7. |
- Li, Constance H., et al.
(författare)
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Sex differences in oncogenic mutational processes
- 2020
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 11
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Tidskriftsartikel (refereegranskat)abstract
- Sex differences have been observed in multiple facets of cancer epidemiology, treatment and biology, and in most cancers outside the sex organs. Efforts to link these clinical differences to specific molecular features have focused on somatic mutations within the coding regions of the genome. Here we report a pan-cancer analysis of sex differences in whole genomes of 1983 tumours of 28 subtypes as part of the ICGC/TCGA Pan-Cancer Analysis of Whole Genomes (PCAWG) Consortium. We both confirm the results of exome studies, and also uncover previously undescribed sex differences. These include sex-biases in coding and non-coding cancer drivers, mutation prevalence and strikingly, in mutational signatures related to underlying mutational processes. These results underline the pervasiveness of molecular sex differences and strengthen the call for increased consideration of sex in molecular cancer research.
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| 8. |
- Møller, Peter, et al.
(författare)
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Inflammation, oxidative stress and genotoxicity responses to biodiesel emissions in cultured mammalian cells and animals
- 2020
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Ingår i: Critical Reviews in Toxicology. - : Informa UK Limited. - 1040-8444 .- 1547-6898. ; 50:5, s. 383-401
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Forskningsöversikt (refereegranskat)abstract
- Biodiesel fuels are alternatives to petrodiesel, especially in the transport sector where they have lower carbon footprint. Notwithstanding the environmental benefit, biodiesel fuels may have other toxicological properties than petrodiesel. Particulate matter (PM) from petrodiesel causes cancer in the lung as a consequence of delivery of genotoxic polycyclic aromatic hydrocarbons, oxidative stress and inflammation. We have reviewed articles from 2002 to 2019 (50% of the articles since 2015) that have described toxicological effects in terms of genotoxicity, oxidative stress and inflammation of biodiesel exhaust exposure in humans, animals and cell cultures. The studies have assessed first generation biodiesel from different feedstock (e.g. rapeseed and soy), certain second generation fuels (e.g. waste oil), and hydrogenated vegetable oil. It is not possible to rank the potency of toxicological effects of specific biodiesel fuels. However, exposure to biodiesel exhaust causes oxidative stress, inflammation and genotoxicity in cell cultures. Three studies in animals have not indicated genotoxicity in lung tissue. The database on oxidative stress and inflammation in animal studies is larger (13 studies); ten studies have reported increased levels of oxidative stress biomarkers or inflammation, although the effects have been modest in most studies. The cell culture and animal studies have not consistently shown a different potency in effect between biodiesel and petrodiesel exhausts. Both increased and decreased potency have been reported, which might be due to differences in feedstock or combustion conditions. In conclusion, combustion products from biodiesel and petrodiesel fuel may evoke similar toxicological effects on genotoxicity, oxidative stress and inflammation.
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| 9. |
- Landegren, Finn, et al.
(författare)
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Simulation based assessment of resilience of two large-scale socio-technical IT networks
- 2018
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Ingår i: International Journal of Critical Infrastructure Protection. - : Elsevier BV. - 1874-5482. ; 23, s. 112-125
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Tidskriftsartikel (refereegranskat)abstract
- Most sectors of modern society are currently undergoing rapid digitalization. With the progress of this development IT networks are becoming an ever more crucial asset whose failure are prone to cause economic losses and risks to health and safety of the population. Due to this development, it is increasingly important that IT networks are designed to be resilient, meaning that they either maintain or quickly recover their functionality when exposed to strains of various kinds. Simulation-based methods that consider supply network topology as well as system for repairing the supply network have previously been applied and found to be useful for assessment of resilience of electricity and water networks. A method of this kind is here applied for IT networks. The method, however, considers only hardware and operator fault modes, not software and dependency faults. The IT networks are studied as socio-technical systems, here broadly understood as systems whose functionality depend on technical as well as organizational sub-systems. The aim of the present paper is to investigate if the method is applicable for assessment of resilience of large-scale IT networks that are critical to society, meaning that (1) it is possible to apply for such systems based on available data, in this case gathered mainly through interviews with focus groups, (2) the results are relevant for users/maintainers/owners of these systems and (3) it captures all relevant factors. The method is tested in case studies on the IT network of a municipality and the SCADA system of a wastewater network. Follow-up interviews were conducted with system managers to assess the perceived relevance of the method and results. It is concluded that the method can be used to obtain the resilience metrics sought for and that the method enables system owners to see if and for what levels of strain they are presently reaching their desired targets concerning system resilience. Follow-up interviews also indicate that the method is perceived by the system managers as being able to support decision making concerning improvement in system resilience.
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| 10. |
- Möller, Peter, et al.
(författare)
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Tourism’s localised population effect in the rural areas of Sweden
- 2018
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Ingår i: Scandinavian Journal of Hospitality and Tourism. - : Informa UK Limited. - 1502-2250 .- 1502-2269. ; :1, s. 39-55
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Tidskriftsartikel (refereegranskat)abstract
- This paper examines how population change among young adults in rural areas is affected when tourism is the dominant industry. The relation between tourism and population change is often implicitly assumed but has not been well examined on a broader societal level. Existing studies have indicated that the effect of tourism on population change is limited in geographical range, and therefore a fine geographical resolution is useful. This analysis is based on yearly information on each individual who resided in Sweden in any year between 1990 and 2010, with 100-metre grid cells as the finest geographical resolution. Since young adults constitute a large part of all migration that takes place, they are the focus of this study. The findings show that the net population change among young adults is clearly more positive in tourism-dominated areas (TDAs) than in non-TDAs, and this becomes more significant the more remote the areas. Further, there is a better gender balance and a younger population in TDAs. Stayers and return migrants can partly explain the positive population change in TDAs, but as shown in previous research, there is a higher turnover of population in TDAs, and in-migration seems to be the key to positive population change.
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