| 1. |
- Elsler, Laura G., et al.
(författare)
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Social relationship dynamics mediate climate impacts on income inequality : evidence from the Mexican Humboldt squid fishery
- 2021
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Ingår i: Regional Environmental Change. - : Springer Science and Business Media LLC. - 1436-3798 .- 1436-378X. ; 21:2
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Tidskriftsartikel (refereegranskat)abstract
- Small-scale fisheries are critically important for livelihoods around the world, particularly in tropical regions. However, climate variability and anthropogenic climate change may seriously impact small-scale fisheries by altering the abundance and distribution of target species. Social relationships between fishery users, such as fish traders, can determine how each individual responds and is affected by changes in fisheries. These informal cooperative and competitive relationships provide access, support, and incentives for fishing and affect the distribution of benefits. Yet, individuals' actions and impacts on individuals are often the primary focus of the economic analyses informing small-scale fisheries' formal management. This focus dismisses relevant social relationships. We argue that this leads to a disconnect between reality and its model representation used in formal management, which may reduce formal fisheries management's efficiency and efficacy and potentially trigger adverse consequences. Here, we examine this argument by comparing the predictions of a simple bioeconomic fishery model with those of a social-ecological model that incorporates the dynamics of cooperative relationships between fish traders. We illustrate model outcomes using an empirical case study in the Mexican Humboldt squid fishery. We find that (1) the social-ecological model with relationship dynamics substantially improves accuracy in predicting observed fishery variables to the simple bioeconomic model. (2) Income inequality outcomes are associated with changes in cooperative trade relationships. When environmental temperature is included in the model as a driver of species production dynamics, we find that climate-driven temperature variability drives a decline in catch that, in turn, reduce fishers' income. We observe an offset of this loss in income by including cooperative relationships between fish traders (oligopoly) in the model. These relationships break down following species distribution changes and result in an increase in prices fishers receive. Finally, (3) our social-ecological model simulations show that the current fishery development program, which seeks to increase fishers' income through an increase in domestic market demand, is supported by predictions from the simple bioeconomic model, may increase income inequality between fishers and traders. Our findings highlight the real and urgent need to re-think fisheries management models in the context of small-scale fisheries and climate change worldwide to encompass social relationship dynamics.
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| 2. |
- Elsler, Laura G., et al.
(författare)
-
Social relationship dynamics mediate climatic impacts on income inequality : evidence from the Mexican Humboldt squid fishery
-
Annan publikation (populärvet., debatt m.m.)abstract
- Small-scale fisheries are ubiquitous and critically important around the world, but they are under serious threat from climatic changes and variability. Climate-driven redistribution of maximum fisheries catch potential is expected to be most severe across tropical regions where small-scale fisheries are widely governed through relationships between fishery users, i.e. fishers and traders. These informal cooperative and competitive relationships provide access, support, and incentives for fishing and affect benefit distribution in fisheries. Yet, their formal management is often informed by economic analyses that focus primarily on the actions of and impacts on individuals. We argue this leads to a disconnect between reality and its model representation, which may reduce the efficiency and efficacy of formal fisheries management and potentially trigger adverse consequences. Here, we examine this argument by comparing the predictions of a simple bioeconomic fishery model with those of a social-ecological model that incorporates the dynamics of cooperative and competitive trade relations in an illustrative, empirical showcase in the Mexican Humboldt squid fishery.We find that (1) the social-ecological model substantially improves accuracy in predicting observed fishery variables compared to the simple bioeconomic model, (2) climate-driven changes in cooperative trade relationships affect fishers’ income and income inequality, and (3) the current fishery development program, that is supported by the predictions of the simple bioeconomic model, may increase income inequality between fishers and traders. Our findings highlight the real and urgent need to re-think the current analytical boundaries of models in the context of small-scale fisheries and climate change worldwide to encompass social relationship dynamics.
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| 3. |
- Heap, Graham A., et al.
(författare)
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HLA-DQA1-HLA-DRB1 variants confer susceptibility to pancreatitis induced by thiopurine immunosuppressants
- 2014
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Ingår i: Nature Genetics. - : Nature Publishing Group. - 1061-4036 .- 1546-1718. ; 46:10, s. 1131-1134
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatitis occurs in approximately 4% of patients treated with the thiopurines azathioprine or mercaptopurine. Its development is unpredictable and almost always leads to drug withdrawal. We identified patients with inflammatory bowel disease (IBD) who had developed pancreatitis within 3 months of starting these drugs from 168 sites around the world. After detailed case adjudication, we performed a genome-wide association study on 172 cases and 2,035 controls with IBD. We identified strong evidence of association within the class II HLA region, with the most significant association identified at rs2647087 (odds ratio 2.59, 95% confidence interval 2.07-3.26, P = 2 x 10(-16)). We replicated these findings in an independent set of 78 cases and 472 controls with IBD matched for drug exposure. Fine mapping of the H LA region identified association with the HLA-DQA1*02:01-HLA-DRB1*07:01 haplotype. Patients heterozygous at rs2647087 have a 9% risk of developing pancreatitis after administration of a thiopurine, whereas homozygotes have a 17% risk.
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| 4. |
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| 5. |
- Ademuyiwa, Adesoji O., et al.
(författare)
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Determinants of morbidity and mortality following emergency abdominal surgery in children in low-income and middle-income countries
- 2016
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Ingår i: BMJ Global Health. - : BMJ Publishing Group Ltd. - 2059-7908. ; 1:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Child health is a key priority on the global health agenda, yet the provision of essential and emergency surgery in children is patchy in resource-poor regions. This study was aimed to determine the mortality risk for emergency abdominal paediatric surgery in low-income countries globally.Methods: Multicentre, international, prospective, cohort study. Self-selected surgical units performing emergency abdominal surgery submitted prespecified data for consecutive children aged <16 years during a 2-week period between July and December 2014. The United Nation's Human Development Index (HDI) was used to stratify countries. The main outcome measure was 30-day postoperative mortality, analysed by multilevel logistic regression.Results: This study included 1409 patients from 253 centres in 43 countries; 282 children were under 2 years of age. Among them, 265 (18.8%) were from low-HDI, 450 (31.9%) from middle-HDI and 694 (49.3%) from high-HDI countries. The most common operations performed were appendectomy, small bowel resection, pyloromyotomy and correction of intussusception. After adjustment for patient and hospital risk factors, child mortality at 30 days was significantly higher in low-HDI (adjusted OR 7.14 (95% CI 2.52 to 20.23), p<0.001) and middle-HDI (4.42 (1.44 to 13.56), p=0.009) countries compared with high-HDI countries, translating to 40 excess deaths per 1000 procedures performed.Conclusions: Adjusted mortality in children following emergency abdominal surgery may be as high as 7 times greater in low-HDI and middle-HDI countries compared with high-HDI countries. Effective provision of emergency essential surgery should be a key priority for global child health agendas.
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| 6. |
- Beecham, Ashley H, et al.
(författare)
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Analysis of immune-related loci identifies 48 new susceptibility variants for multiple sclerosis.
- 2013
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Ingår i: Nature genetics. - : Springer Science and Business Media LLC. - 1546-1718 .- 1061-4036. ; 45:11, s. 1353-60
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Tidskriftsartikel (refereegranskat)abstract
- Using the ImmunoChip custom genotyping array, we analyzed 14,498 subjects with multiple sclerosis and 24,091 healthy controls for 161,311 autosomal variants and identified 135 potentially associated regions (P < 1.0 × 10(-4)). In a replication phase, we combined these data with previous genome-wide association study (GWAS) data from an independent 14,802 subjects with multiple sclerosis and 26,703 healthy controls. In these 80,094 individuals of European ancestry, we identified 48 new susceptibility variants (P < 5.0 × 10(-8)), 3 of which we found after conditioning on previously identified variants. Thus, there are now 110 established multiple sclerosis risk variants at 103 discrete loci outside of the major histocompatibility complex. With high-resolution Bayesian fine mapping, we identified five regions where one variant accounted for more than 50% of the posterior probability of association. This study enhances the catalog of multiple sclerosis risk variants and illustrates the value of fine mapping in the resolution of GWAS signals.
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| 7. |
- Chrysafi, Anna, et al.
(författare)
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Quantifying Earth system interactions for sustainable food production via expert elicitation
- 2022
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Ingår i: Nature Sustainability. - : Springer Science and Business Media LLC. - 2398-9629. ; 5:10, s. 830-842
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Tidskriftsartikel (refereegranskat)abstract
- Several safe boundaries of critical Earth system processes have already been crossed due to human perturbations; not accounting for their interactions may further narrow the safe operating space for humanity. Using expert knowledge elicitation, we explored interactions among seven variables representing Earth system processes relevant to food production, identifying many interactions little explored in Earth system literature. We found that green water and land system change affect other Earth system processes strongly, while land, freshwater and ocean components of biosphere integrity are the most impacted by other Earth system processes, most notably blue water and biogeochemical flows. We also mapped a complex network of mechanisms mediating these interactions and created a future research prioritization scheme based on interaction strengths and existing knowledge gaps. Our study improves the understanding of Earth system interactions, with sustainability implications including improved Earth system modelling and more explicit biophysical limits for future food production.
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| 8. |
- Datseris, George, et al.
(författare)
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Agents.jl : a performant and feature-full agent-based modeling software of minimal code complexity
- 2022
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Ingår i: Simulation (San Diego, Calif.). - : SAGE Publications. - 0037-5497 .- 1741-3133.
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Tidskriftsartikel (refereegranskat)abstract
- Agent-based modeling is a simulation method in which autonomous agents interact with their environment and one another, given a predefined set of rules. It is an integral method for modeling and simulating complex systems, such as socio-economic problems. Since agent-based models are not described by simple and concise mathematical equations, the code that generates them is typically complicated, large, and slow. Here we present Agents.jl, a Julia-based software that provides an ABM analysis platform with minimal code complexity. We compare our software with some of the most popular ABM software in other programming languages. We find that Agents.jl is not only the most performant but also the least complicated software, providing the same (and sometimes more) features as the competitors with less input required from the user. Agents.jl also integrates excellently with the entire Julia ecosystem, including interactive applications, differential equations, parameter optimization, and so on. This removes any extensions library requirement from Agents.jl, which is paramount in many other tools.
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| 9. |
- Dubois, Timothy, 1982, et al.
(författare)
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Origins of plateau formation in ion energy spectra under target normal sheath acceleration
- 2017
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 24:12, s. 123114-
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Tidskriftsartikel (refereegranskat)abstract
- Target normal sheath acceleration (TNSA) is a method employed in laser–matter interaction experiments to accelerate light ions (usually protons). Laser setups with durations of a few 10 fs and relatively low intensity contrasts observe plateau regions in their ion energy spectra when shooting on thin foil targets with thicknesses of the order of 10 μm. In this paper, we identify a mechanism which explains this phenomenon using one-dimensional particle-in-cell simulations. Fast electrons generated from the laser interaction recirculate back and forth through the target, giving rise to time-oscillating charge and current densities at the target backside. Periodic decreases in the electron density lead to transient disruptions of the TNSA sheath field: peaks in the ion spectra form as a result, which are then spread in energy from a modified potential driven by further electron recirculation. The ratio between the laser pulse duration and the recirculation period (dependent on the target thickness, including the portion of the pre-plasma which is denser than the critical density) determines if a plateau forms in the energy spectra.
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| 10. |
- Ferri, Julien, 1990, et al.
(författare)
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Proton acceleration by a pair of successive ultraintense femtosecond laser pulses
- 2018
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 25
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Tidskriftsartikel (refereegranskat)abstract
- © 2018 Author(s). We investigate the target normal sheath acceleration of protons in thin aluminum targets irradiated at a relativistic intensity by two time-separated ultrashort (35 fs) laser pulses. When the full-energy laser pulse is temporally split into two identical half-energy pulses, and using target thicknesses of 3 and 6 μm, we observe experimentally that the second half-pulse boosts the maximum energy and charge of the proton beam produced by the first half-pulse for time delays below ∼0.6-1 ps. Using two-dimensional particle-in-cell simulations, we examine the variation of the proton energy spectra with respect to the time-delay between the two pulses. We demonstrate that the expansion of the target front surface caused by the first pulse significantly enhances the hot-electron generation by the second pulse arriving after a few hundreds of fs time delay. This enhancement, however, does not suffice to further accelerate the fastest protons driven by the first pulse once three-dimensional quenching effects have set in. This implies a limit to the maximum time delay that leads to proton energy enhancement, which we theoretically determine.
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| 11. |
- Hesslow, Linnea, 1993, et al.
(författare)
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Effect of partially-screened nuclei on fast-electron dynamics
- 2017
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Ingår i: Physical Review Letters. - 1079-7114 .- 0031-9007. ; 118:25, s. article no. 5501-
-
Tidskriftsartikel (refereegranskat)abstract
- We analyze the dynamics of fast electrons in plasmas containing partially ionized impurity atoms, where the screening effect of bound electrons must be included. We derive analytical expressions for the deflection and slowing-down frequencies, and show that they are increased significantly compared to the results obtained with complete screening, already at sub-relativistic electron energies. Furthermore, we show that the modifications to the deflection and slowing down frequencies are of equal importance in describing the runaway current evolution. Our results greatly affect fast-electron dynamics and have important implications, e.g. for the efficacy of mitigation strategies for runaway electrons in tokamak devices, and energy loss during relativistic breakdown in atmospheric discharges.
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| 12. |
- Hesslow, Linnea, 1993, et al.
(författare)
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Fast-electron dynamics in the presence of weakly ionized impurities
- 2017
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Ingår i: 44th EPS Conference on Plasma Physics, EPS 2017.
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Konferensbidrag (refereegranskat)abstract
- Runaway electrons constitute a significant threat to tokamak experiments. To minimize the risk of damage, it is crucial to understand the runaway-electron dynamics, which during runaway mitigation can be heavily influenced by the interaction with partially ionized atoms. Experiments have shown that mitigation via heavy-impurity injection is more effective than would be expected from standard collisional theory, highlighting the need for more accurate kinetic models. To achieve this, partial screening of the nuclei by the bound electrons must be taken into account. In this contribution, we analyze the dynamics of fast electrons in plasmas containing partially ionized impurity atoms. A generalized collision operator is derived from first principles using quantum-mechanical models. We obtain analytical expressions for the deflection and slowing-down frequencies, and show that they are increased by more than an order of magnitude compared to the results obtained with complete screening, already at sub-relativistic electron energies. Moreover, we implement the generalized collision operator in the continuum kinetic equation solver CODE and demonstrate that interaction with partially ionized atoms greatly affects fast-electron dynamics by enhancing the rates of angular deflection and energy loss. This has important implications, not only for the efficacy of mitigation strategies for runaway electrons in tokamak devices, but also for example for energy loss during relativistic breakdown in lightning discharges.
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| 13. |
- Hesslow, Linnea, 1993, et al.
(författare)
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Generalized collision operator for fast electrons interacting with partially ionized impurities
- 2018
-
Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 84:6
-
Tidskriftsartikel (refereegranskat)abstract
- Accurate modelling of the interaction between fast electrons and partially ionized atoms is important for evaluating tokamak disruption mitigation schemes based on material injection. This requires accounting for the effect of screening of the impurity nuclei by the cloud of bound electrons. In this paper, we generalize the Fokker–Planck operator in a fully ionized plasma by accounting for the effect of screening. We detail the derivation of this generalized operator, and calculate the effective ion length scales, needed in the components of the collision operator, for a number of ion species commonly appearing in fusion experiments. We show that for high electric fields, the secondary runaway growth rate can be substantially larger than in a fully ionized plasma with the same effective charge, although the growth rate is significantly reduced at near-critical electric fields. Furthermore, by comparison with the Boltzmann collision operator, we show that the Fokker–Planck formalism is accurate even for large impurity content.
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| 14. |
- Hesslow, Linnea, 1993, et al.
(författare)
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Kinetic effects of partially screened impurities in runaway-electron mitigation scenarios
- 2017
-
Ingår i: International Sherwood Fusion Theory Conference, Annapolis, USA.
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Runaway electrons constitute a significant threat to tokamak devices. Their mitigation by heavy-impurity injection has been experimentally shown to be more effective than would be expected from standard collisional theory [1]. In order to understand this effect and develop runaway mitigation schemes, more accurate kinetic models are needed to describe the interaction between electrons and partially ionized atoms. Such models require the partial screening of the nuclei by the bound electrons to be taken into account.In this contribution, we analyze the dynamics of fast electrons in plasmas containing partially ionized impurity atoms. A generalized collision operator is derived from first principles using quantum-mechanical models. We obtain analytical expressions for the deflection and slowing-down frequencies. Even at sub-relativistic energies, these are increased by more than an order of magnitude compared to the results obtained with complete screening. Moreover, we implement the generalized collision operator in the continuum kinetic-equation solver CODE [2, 3] and demonstrate that interaction with partially ionized atoms greatly affects fast-electron dynamics by enhancing the rates of angular deflection and energy loss. In particular, we investigate the decay of a runaway-electron current coupled to a self-consistent electric field. The effect of the interaction with partially ionized impurities has important implications for the efficacy of mitigation strategies for runaway electrons in tokamak devices.References[1] E. M. Hollmann et al., Physics of Plasmas 22, 056108 (2015).[2] M. Landreman, A. Stahl and T. Fülöp, Comp. Phys. Comm. 185, 847 (2014).[3] A. Stahl et al., Nuclear Fusion 56, 112009 (2016).
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| 15. |
- Jelenkovic, Aline, et al.
(författare)
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Zygosity Differences in Height and Body Mass Index of Twins From Infancy to Old Age : A Study of the CODATwins Project
- 2015
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Ingår i: Twin Research and Human Genetics. - : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 18:5, s. 557-570
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Tidskriftsartikel (refereegranskat)abstract
- A trend toward greater body size in dizygotic (DZ) than in monozygotic (MZ) twins has been suggested by some but not all studies, and this difference may also vary by age. We analyzed zygosity differences in mean values and variances of height and body mass index (BMI) among male and female twins from infancy to old age. Data were derived from an international database of 54 twin cohorts participating in the COllaborative project of Development of Anthropometrical measures in Twins (CODATwins), and included 842,951 height and BMI measurements from twins aged 1 to 102 years. The results showed that DZ twins were consistently taller than MZ twins, with differences of up to 2.0 cm in childhood and adolescence and up to 0.9 cm in adulthood. Similarly, a greater mean BMI of up to 0.3 kg/m(2) in childhood and adolescence and up to 0.2 kg/m(2) in adulthood was observed in DZ twins, although the pattern was less consistent. DZ twins presented up to 1.7% greater height and 1.9% greater BMI than MZ twins; these percentage differences were largest in middle and late childhood and decreased with age in both sexes. The variance of height was similar in MZ and DZ twins at most ages. In contrast, the variance of BMI was significantly higher in DZ than in MZ twins, particularly in childhood. In conclusion, DZ twins were generally taller and had greater BMI than MZ twins, but the differences decreased with age in both sexes.
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| 16. |
- Sánchez Van Kammen, Mayte, et al.
(författare)
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Characteristics and Outcomes of Patients with Cerebral Venous Sinus Thrombosis in SARS-CoV-2 Vaccine-Induced Immune Thrombotic Thrombocytopenia
- 2021
-
Ingår i: JAMA Neurology. - : American Medical Association. - 2168-6149 .- 2168-6157. ; 78:11, s. 1314-1323
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Tidskriftsartikel (refereegranskat)abstract
- Importance: Thrombosis with thrombocytopenia syndrome (TTS) has been reported after vaccination with the SARS-CoV-2 vaccines ChAdOx1 nCov-19 (Oxford-AstraZeneca) and Ad26.COV2.S (Janssen/Johnson & Johnson).Objective: To describe the clinical characteristics and outcome of patients with cerebral venous sinus thrombosis (CVST) after SARS-CoV-2 vaccination with and without TTS.Design, Setting, and Participants: This cohort study used data from an international registry of consecutive patients with CVST within 28 days of SARS-CoV-2 vaccination included between March 29 and June 18, 2021, from 81 hospitals in 19 countries. For reference, data from patients with CVST between 2015 and 2018 were derived from an existing international registry. Clinical characteristics and mortality rate were described for adults with (1) CVST in the setting of SARS-CoV-2 vaccine-induced immune thrombotic thrombocytopenia, (2) CVST after SARS-CoV-2 vaccination not fulling criteria for TTS, and (3) CVST unrelated to SARS-CoV-2 vaccination.Exposures: Patients were classified as having TTS if they had new-onset thrombocytopenia without recent exposure to heparin, in accordance with the Brighton Collaboration interim criteria.Main Outcomes and Measures: Clinical characteristics and mortality rate.Results: Of 116 patients with postvaccination CVST, 78 (67.2%) had TTS, of whom 76 had been vaccinated with ChAdOx1 nCov-19; 38 (32.8%) had no indication of TTS. The control group included 207 patients with CVST before the COVID-19 pandemic. A total of 63 of 78 (81%), 30 of 38 (79%), and 145 of 207 (70.0%) patients, respectively, were female, and the mean (SD) age was 45 (14), 55 (20), and 42 (16) years, respectively. Concomitant thromboembolism occurred in 25 of 70 patients (36%) in the TTS group, 2 of 35 (6%) in the no TTS group, and 10 of 206 (4.9%) in the control group, and in-hospital mortality rates were 47% (36 of 76; 95% CI, 37-58), 5% (2 of 37; 95% CI, 1-18), and 3.9% (8 of 207; 95% CI, 2.0-7.4), respectively. The mortality rate was 61% (14 of 23) among patients in the TTS group diagnosed before the condition garnered attention in the scientific community and 42% (22 of 53) among patients diagnosed later.Conclusions and Relevance: In this cohort study of patients with CVST, a distinct clinical profile and high mortality rate was observed in patients meeting criteria for TTS after SARS-CoV-2 vaccination..
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| 17. |
- Scutelnic, Adrian, et al.
(författare)
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Management of Cerebral Venous Thrombosis Due to Adenoviral COVID-19 Vaccination.
- 2022
-
Ingår i: Annals of neurology. - : Wiley. - 1531-8249 .- 0364-5134. ; 92:4, s. 562-573
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Tidskriftsartikel (refereegranskat)abstract
- Cerebral venous thrombosis (CVT) caused by vaccine-induced immune thrombotic thrombocytopenia (VITT) is a rare adverse effect of adenovirus-based severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) vaccines. In March 2021, after autoimmune pathogenesis of VITT was discovered, treatment recommendations were developed. These comprised immunomodulation, non-heparin anticoagulants, and avoidance of platelet transfusion. The aim of this study was to evaluate adherence to these recommendations and its association with mortality.We used data from an international prospective registry of patients with CVT after the adenovirus-based SARS-CoV-2 vaccination. We analyzed possible, probable, or definite VITT-CVT cases included until January 18, 2022. Immunomodulation entailed administration of intravenous immunoglobulins and/or plasmapheresis.Ninety-nine patients with VITT-CVT from 71 hospitals in 17 countries were analyzed. Five of 38 (13%), 11 of 24 (46%), and 28 of 37 (76%) of the patients diagnosed in March, April, and from May onward, respectively, were treated in-line with VITT recommendations (p<0.001). Overall, treatment according to recommendations had no statistically significant influence on mortality (14/44 [32%] vs 29/55 [52%], adjusted odds ratio [OR]=0.43, 95% confidence interval [CI]=0.16-1.19). However, patients who received immunomodulation had lower mortality (19/65 [29%] vs 24/34 [70%], adjusted OR=0.19, 95% CI=0.06-0.58). Treatment with non-heparin anticoagulants instead of heparins was not associated with lower mortality (17/51 [33%] vs 13/35 [37%], adjusted OR=0.70, 95% CI=0.24-2.04). Mortality was also not significantly influenced by platelet transfusion (17/27 [63%] vs 26/72 [36%], adjusted OR=2.19, 95% CI=0.74-6.54).In patients with VITT-CVT, adherence to VITT treatment recommendations improved over time. Immunomodulation seems crucial for reducing mortality of VITT-CVT. ANN NEUROL 2022;92:562-573.
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| 18. |
- Silventoinen, Karri, et al.
(författare)
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The CODATwins Project : The Cohort Description of Collaborative Project of Development of Anthropometrical Measures in Twins to Study Macro-Environmental Variation in Genetic and Environmental Effects on Anthropometric Traits
- 2015
-
Ingår i: Twin Research and Human Genetics. - : Cambridge University Press. - 1832-4274 .- 1839-2628. ; 18:4
-
Tidskriftsartikel (refereegranskat)abstract
- For over 100 years, the genetics of human anthropometric traits has attracted scientific interest. In particular, height and body mass index (BMI, calculated as kg/m2) have been under intensive genetic research. However, it is still largely unknown whether and how heritability estimates vary between human populations. Opportunities to address this question have increased recently because of the establishment of many new twin cohorts and the increasing accumulation of data in established twin cohorts. We started a new research project to analyze systematically (1) the variation of heritability estimates of height, BMI and their trajectories over the life course between birth cohorts, ethnicities and countries, and (2) to study the effects of birth-related factors, education and smoking on these anthropometric traits and whether these effects vary between twin cohorts. We identified 67 twin projects, including both monozygotic (MZ) and dizygotic (DZ) twins, using various sources. We asked for individual level data on height and weight including repeated measurements, birth related traits, background variables, education and smoking. By the end of 2014, 48 projects participated. Together, we have 893,458 height and weight measures (52% females) from 434,723 twin individuals, including 201,192 complete twin pairs (40% monozygotic, 40% same-sex dizygotic and 20% opposite-sex dizygotic) representing 22 countries. This project demonstrates that large-scale international twin studies are feasible and can promote the use of existing data for novel research purposes.
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| 19. |
- Skvortsov, Alex, et al.
(författare)
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Scaling laws for extremely strong thermals
- 2021
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Ingår i: Physical Review Fluids. - 2469-990X. ; 6:5
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Tidskriftsartikel (refereegranskat)abstract
- A rich variety of scaling laws for the evolution of convective buoyant thermals generated by an explosive release of energy has been established. Such events may correspond to a blast, spark, or volcano eruption. It was found that an occurrence of a particular scaling law depends on the interplay of many factors, viz., (1) amount of energy released in the environment, (2) time since the release, and (3) spatial scale of the release domain. The analytical treatment involves solutions of coupled equations for mass, momentum and buoyancy (heat) conservation in the Boussinesq and non-Boussinesq approximation. A model for the entrainment flow that accounts for a strong thermal flux has been proposed. For the limiting case of a weak thermal and the Boussinesq approximation (low density contrast between the buoyant thermal and the ambient environment) the celebrated Batchelor, Morton, and Turner scalings are recovered. Results have been favorably compared with limited data available in the literature.
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| 20. |
- Svedung Wettervik, Benjamin, 1990, et al.
(författare)
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Laser-driven collisionless shock acceleration of protons
- 2016
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Ingår i: 43rd European Physical Society Conference on Plasma Physics, EPS 2016.
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Konferensbidrag (refereegranskat)abstract
- Experimental and numerical results have shown that collisionless shock acceleration is promis-ing for generation of high energy proton beams. There are many potential applications for suchbeams, for example: isotope generation for medical applications, ion therapy and proton radio-graphy. In this work, we use 1D1P Eulerian Vlasov-Maxwell simulations to study shock waveacceleration. Vlasov-Maxwell modeling allows for high resolution of the distribution functionand is highly suitable in cases where effects of low-density tails in the distribution function needto be resolved accurately.We find that combining collisionless shock acceleration with a strong, quasi-stationary sheath-field may be a way to reach even higher maximum proton energies and optimize the ion spec-trum. We show that a layered plasma target with a combination of light and heavy ions leads toa strong quasi-static sheath-field, which induces an enhancement of the energy of shock-waveaccelerated ions, without broadening their energy spectrum, if the heavy ion layer has highdensity.
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| 21. |
- Svedung Wettervik, Benjamin, 1990, et al.
(författare)
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Relativistic Vlasov-Maxwell modelling using finite volumes and adaptive mesh refinement
- 2017
-
Ingår i: European Physical Journal D. - : Springer Science and Business Media LLC. - 1434-6079 .- 1434-6060. ; 71:6, s. 157-
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Tidskriftsartikel (refereegranskat)abstract
- The dynamics of collisionless plasmas can be modelled by the Vlasov-Maxwell system of equations. An Eulerian approach is needed to accurately describe processes that are governed by high energy tails in the distribution function, but is of limited efficiency for high dimensional problems. The use of an adaptive mesh can reduce the scaling of the computational cost with the dimension of the problem. Here, we present a relativistic Eulerian Vlasov-Maxwell solver with block-structured adaptive mesh refinement in one spatial and one momentum dimension. The discretization of the Vlasov equation is based on a high-order finite volume method. A flux corrected transport algorithm is applied to limit spurious oscillations and ensure the physical character of the distribution function. We demonstrate a speed-up by a factor of 7 × in a typical scenario involving laser pulse interaction with an underdense plasma due to the use of an adaptive mesh.
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| 22. |
- Svedung Wettervik, Benjamin, 1990, et al.
(författare)
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Vlasov modelling of laser-driven collisionless shock acceleration of protons
- 2016
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1089-7674 .- 1070-664X. ; 23:5, s. 053103-
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Tidskriftsartikel (refereegranskat)abstract
- Ion acceleration due to the interaction between a short high-intensity laser pulse and a moderatelyoverdense plasma target is studied using Eulerian Vlasov-Maxwell simulations. The e ects ofvariations in the plasma density pro le and laser pulse parameters are investigated, and theinterplay of collisionless shock and target normal sheath acceleration is analyzed. It is shownthat the use of a layered-target with a combination of light and heavy ions, on the front and rearside respectively, yields a strong quasi-static sheath- eld on the rear side of the heavy-ion part ofthe target. This sheath- eld increases the energy of the shock-accelerated ions while preservingtheir mono-energeticity
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| 23. |
- Thomas, HS, et al.
(författare)
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- 2019
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swepub:Mat__t
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