| 1. |
- Alfredsson, Anders, 1977-, et al.
(författare)
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A Comparison of Pointwise and Levelling Assisted Regional Realisations of IHRS with a Case Study over Sweden
- 2023
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Ingår i: International Association of Geodesy Symposia. - : Springer Berlin/Heidelberg.
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Bokkapitel (refereegranskat)abstract
- The International Height Reference System (IHRS) was defined by the International Association of Geodesy (IAG) in 2015. The global International Height Reference Frame (IHRF) should provide access to the IHRS in a broad sense. To provide high accuracy local access, regional (or national) realisations will also be needed. This study aims at evaluating different approaches to compute a denser regional realisation of IHRS in case a high accuracy levelling network is available. Using Sweden as a case study region, a GNSS (Global Navigation Satellite System) and geoid based pointwise realisation is compared with three types of levelling assisted realisations. The latter are made by applying least squares adjustments of the precise levelling observations with fixed potential value(s) from either the global IHRF station in Sweden or the pointwise potentials of a larger number of stations. It is concluded that making a minimum constraint adjustment with one station fixed is not the best option. It is favourable to fix a reasonable number of pointwise stations at an internal distance over which the relative uncertainty of levelling is significantly lower than the relative uncertainty of the pointwise solution. The investigation is made using levelling data from the third precise levelling of Sweden, the NKG2015 quasigeoid model and the NKG2016LU postglacial land uplift model.
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| 2. |
- Bolmsvik, Åsa, 1975-
(författare)
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Structural-acoustic vibrations in wooden assemblies : Experimental modal analysis and finite element modelling
- 2013
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- This doctoral thesis concerns flanking transmission in light weight, wooden multi-storey buildings within the low frequency, primarily 20-120 Hz. The overall aim is to investigate how the finite element method can contribute in the design phase to evaluate different junctions regarding flanking transmission.Two field measurements of accelerations in light weight wooden buildings have been evaluated. In these, two sources; a stepping machine, and an electrodynamic shaker, were used. The shaker was shown to give more detailed information. However, since a light weight structure in field exhibit energy losses to surrounding building parts, reliable damping estimates were difficult to obtain.In addition, two laboratory measurements were made. These were evaluated using experimental modal analysis, giving the eigenmodes and the damping of the structures. The damping for these particular structures varies significantly with frequency, especially when an elastomer is used in the floor-wall junction. The overall damping is also higher when elastomers are used in the floor-wall junction in comparison to a screwed junction. By analysing the eigenmodes, using the modal assurance criterion, of the same structure with two types of junctions it was concluded that the modes become significantly different. Thereby the overall behavior differs.Several finite element models representing both the field and laboratory test setups have been made. The junctions between the building blocks in the models have been modeled using tie or springs and dashpots. Visual observation and the modal assurance criterion show that there is more rotational stiffness in the test structures than in the models.The findings in this doctoral thesis add understanding to how modern joints in wooden constructions can be represented by FE modelling. They will contribute in developing FE models that can be used to see the acoustic effects prior to building an entire house. However, further research is still needed.
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| 3. |
- Gustafsson, Åsa, et al.
(författare)
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Mice with established airway inflammation exert differential cellular responses to inhaled hematite nanoparticles than healthy mice
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- The aim of this study was to investigate the inflammatory and immunological responses in the airways and the lung-draining lymph nodes, following lung exposure to hematite nanoparticles (NPs). The responses to hematite NPs were evaluated in both non-sensitized healthy mice, and allergen-sensitized mice, in which the latter represent a group of sensitive individuals with allergic airway disease. This allergic airway disease was induced by sensitization and aerosol challenge to a respiratory allergen resulting in an established eosinophilic and lymphocytic airway inflammation at the time of NP exposure. The mice received either hematite NPs or vehicle (PBS) intratracheally and the cellular responses were evaluated on day 1, 2, and 7, following exposure.Intratracheal instillation of hematite NPs induced an increase of neutrophils, eosinophils, and lymphocytes in the airways of non-sensitized mice on day 1 and 2 following exposure. At these time-points the lymphocytes in the lymph nodes were also increased. In contrast, exposure to hematite NPs in sensitized mice induced a rapid and unspecific cellular reduction in the alveolar space on the first day after exposure. A similar decrease of lymphocytes was also observed in the mediastinal lymph nodes draining the airways. The study did not indicate a reduction of inflammatory cells in the lung tissue or a translocation of cells from alveolar space to lung tissue. Although, mucociliary cellular clearance could be a possible explanation, our finding of cellular decrease also in lung draining lymph nodes point at cell death as the most likely cause to this unspecific cellular reduction.The results indicate that cells in the airways and lymph nodes of individuals with established airway inflammation undergo cell death when exposed to iron oxide NPs. A possible reason to the toxic response is extensive generation of reactive oxygen species (ROS) in the pro-oxidative environment of inflamed airways, which is further catalyzed by Fe ions released by the hematite NPs, or by generation of ROS at the surface of the NPs. Such cell toxic response was not detected in healthy non-sensitized individuals. This study clearly demonstrates the different response of sensitized and non-sensitized mice, and highlights the importance of including individuals with respiratory disorders, such as allergic asthma, when evaluating health effects of inhaled nanomaterials.
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| 4. |
- Lindgren, Göran, 1948-
(författare)
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Studies in conflict economics and economic growth
- 2006
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- “Armaments and Economic Performance”. The literature on military expenditure (milex) is scrutinized with respect to five areas. Investment is reduced when milex increases. Most studies have found economic growth hindered by higher milex. No clear association between milex and employment is found. However, the same amount of other public expenditure creates more jobs. There is some evidence for milex as counter-cyclical instrument in the US. The result for studies if milex is used in electoral cycles in the US is contradictory. Disaggregated data are emphasized as a possible solution to get more definite results.“The Economic Costs of Civil Wars”. The empirical studies of the economic costs of internal armed conflicts are divided into accounting and modelling methods. Cost is seen as the difference between the counterfactual production without conflict and the actual production. The average economic cost of internal armed conflict is a 3.7% yearly reduction of GDP. There are large differences between the estimates. One of the reasons for pursuing such studies is to give improved basis for more cost-effective post-conflict reconstruction, which is better achieved with an accounting method.“War and Economic Performance – Different Data, Different Conclusions?” This article studies the importance of armed conflict for economic growth by replicating an earlier analysis with new data on conflicts. The basic model investigates how conflicts in 1960-1974 affect economic growth in 1975-1989. Koubi finds that “wars are conducive to higher growth”. Koubi’s finding is confirmed when different conflict data is used in a similar research design.“The Role of External Factors in Economic Growth: A Comparative Analysis of Thailand and the Philippines 1950-1990”. Can differences in economic performance be explained by external factors? Both historical and regression analyses are utilised to answer the question. Three external factors are analysed: International trade, foreign direct investment, and external debt. In the regression analysis none of the external factors qualify as statistically significant. The historical analysis finds two external factors discriminating between the two countries. Thus, they might explain the differing growth rates of Thailand and the Philippines: Manufactured exports and external debt.
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| 5. |
- Nilsson, Åsa, et al.
(författare)
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Modellering av råvaruflödet i skogliga värdekedjor, inklusive råvaruegenskaper och hållbarhetsaspekter
- 2021
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Detta är en delrapport från programmet Mistra Digital Forest. Rapporten beskriver den inledande utvecklingen av verktyget BioMapp. Vidare beskrivs vilka digitala data som kan användas som indata för att driva simuleringar med verktyget samt hur den fortsatta utvecklingen planeras inom Mistra Digital Forest. BioMapp är tänkt att användas för att bidra till en ökad förståelse av hur den skogliga råvaran fördelas på olika produktgrupper, samt för att beräkna ett antal hållbarhetsindikatorer för varje steg i förädlingsprocessen. Dessutom ska BioMapp kunna visualisera och beräkna effekter av ändrade strategier i råvaruförsörjningen, tex om flödet av skogsråvara styrs till industrikunden baserat på ved- och fiberegenskaper i högre grad än i dag.
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| 6. |
- Stenberg, Erik, 1979-, et al.
(författare)
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Closure of mesenteric defects in laparoscopic gastric bypass : a multicentre, randomised, parallel, open-label trial
- 2016
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Ingår i: The Lancet. - : Elsevier. - 0140-6736 .- 1474-547X. ; 387:10026, s. 1397-1404
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Tidskriftsartikel (refereegranskat)abstract
- Background: Small bowel obstruction due to internal hernia is a common and potentially serious complication after laparoscopic gastric bypass surgery. Whether closure of surgically created mesenteric defects might reduce the incidence is unknown, so we did a large randomised trial to investigate.Method: This study was a multicentre, randomised trial with a two-arm, parallel design done at 12 centres for bariatric surgery in Sweden. Patients planned for laparoscopic gastric bypass surgery at any of the participating centres were off ered inclusion. During the operation, a concealed envelope was opened and the patient was randomly assigned to either closure of mesenteric defects beneath the jejunojejunostomy and at Petersen's space or non-closure. After surgery, assignment was open label. The main outcomes were reoperation for small bowel obstruction and severe postoperative complications. Outcome data and safety were analysed in the intention-to-treat population. This trial is registered with ClinicalTrials. gov, number NCT01137201.Findings: Between May 1, 2010, and Nov 14, 2011, 2507 patients were recruited to the study and randomly assigned to closure of the mesenteric defects (n= 1259) or non-closure (n= 1248). 2503 (99.8%) patients had follow-up for severe postoperative complications at day 30 and 2482 (99.0%) patients had follow-up for reoperation due to small bowel obstruction at 25 months. At 3 years after surgery, the cumulative incidence of reoperation because of small bowel obstruction was signifi cantly reduced in the closure group (cumulative probability 0.055 for closure vs 0.102 for non-closure, hazard ratio 0.56, 95% CI 0.41-0.76, p= 0.0002). Closure of mesenteric defects increased the risk for severe postoperative complications (54 [4.3%] for closure vs 35 [2.8%] for non-closure, odds ratio 1.55, 95% CI 1.01-2.39, p= 0.044), mainly because of kinking of the jejunojejunostomy.Interpretation: The results of our study support the routine closure of the mesenteric defects in laparoscopic gastric bypass surgery. However, closure of the mesenteric defects might be associated with increased risk of early small bowel obstruction caused by kinking of the jejunojejunostomy.
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| 7. |
- Ågren, Magnus, 1984, et al.
(författare)
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Architecture evaluation in continuous development
- 2022
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Ingår i: Journal of Systems and Software. - : Elsevier BV. - 0164-1212. ; 184
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Tidskriftsartikel (refereegranskat)abstract
- Context: In automotive, stage-gate processes have previously been the norm, with architecture created mainly during an early phase and then used to guide subsequent development phases. Current iterative and Agile development methods, where the implementation evolves continuously, changes the role of architecture. Objective: We investigate how architecture evaluation can provide useful feedback during development of continuously evolving systems. Method: Starting from the Architecture Tradeoff Analysis Method (ATAM), we performed architecture evaluation, both in a national research project led by an automotive Original Equipment Manufacturer (OEM), and at the OEM, in the context of continuous development. This allows us to include the experience of several architects from different organizations over several years. Using data produced during the evaluations we perform a post-hoc analysis to derive initial findings. We then validate and refine these findings through a series of focus groups with architects and industry experts. Findings: We propose principles of continuous evaluation and evolution of architecture, and based on these discuss a roadmap for future research. Conclusion: In iterative development settings, the needs are different from what typical architecture evaluation methods provide. Our principles show the importance of dedicated feedback-loops for continuous evolution of systems and their architecture.
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| 8. |
- Aidas, Kestutis, et al.
(författare)
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The Dalton quantum chemistry program system
- 2014
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Ingår i: WIREs Computational Molecular Science. - : Wiley. - 1759-0876 .- 1759-0884. ; 4:3, s. 269-284
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Tidskriftsartikel (refereegranskat)abstract
- Dalton is a powerful general-purpose program system for the study of molecular electronic structure at the Hartree-Fock, Kohn-Sham, multiconfigurational self-consistent-field, MOller-Plesset, configuration-interaction, and coupled-cluster levels of theory. Apart from the total energy, a wide variety of molecular properties may be calculated using these electronic-structure models. Molecular gradients and Hessians are available for geometry optimizations, molecular dynamics, and vibrational studies, whereas magnetic resonance and optical activity can be studied in a gauge-origin-invariant manner. Frequency-dependent molecular properties can be calculated using linear, quadratic, and cubic response theory. A large number of singlet and triplet perturbation operators are available for the study of one-, two-, and three-photon processes. Environmental effects may be included using various dielectric-medium and quantum-mechanics/molecular-mechanics models. Large molecules may be studied using linear-scaling and massively parallel algorithms. Dalton is distributed at no cost from for a number of UNIX platforms.
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| 9. |
- Alfredsson, Anders, et al.
(författare)
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A first step towards a national realisation of the international height reference system in Sweden with a comparison to RH 2000
- 2023
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Ingår i: Journal of Geodetic Science. - : de Gruyter. - 2081-9919 .- 2081-9943. ; 13:1
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Tidskriftsartikel (refereegranskat)abstract
- The International Height Reference System (IHRS) was defined by the International Association of Geodesy in 2015. Since then, the international geodetic community has been working on the specification and establishment of its realisation, the International Height Reference Frame (IHRF). This frame will primarily be realised by geopotential numbers (or physical heights) in a sparse global reference network. In Sweden, only one such global station is planned. Regional and national realisations (or densifications) computed in accordance with the IHRS definition are needed to enable the best possible unification of height datums. The main purpose of this article is to make a case study for Sweden regarding the national realisation of IHRS and to investigate in what way preliminary IHRF differs from the current Swedish levelling-based realisation of the European Vertical Reference System, RH 2000. The two different quasigeoid models that we consider best over Sweden at the present time are used to compute the preliminary IHRS realisations in the study. The realisations are compared to each other and to RH 2000. It is shown that a very significant part of the difference to RH 2000 is due to the different postglacial land uplift epochs, permanent tide concepts, and zero levels. The standard deviation for the difference between one of the preliminary national IHRS realisations and RH 2000 is reduced from 75.5 to 19.2 mm after correction of the postglacial land uplift and permanent tide effects. The corresponding mean differences are –208.5 and –454.7 mm, respectively. The magnitude of the mean difference thus increases when the corrections in question are applied.
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| 10. |
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| 11. |
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| 12. |
- Andersson, Jonas, et al.
(författare)
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Volatility modeling in the presence of measurement errors
- 2001
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Ingår i: Journal of Risk. - 1465-1211. ; 3:4, s. 53-67
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, the authors examine the effects of measurement errors on volatility measures. This is done by first expressing the moment properties of general volatility models with measurement errors in terms of the corresponding moments for the underlying unobserved signal process. Then the consequences of measurement errors for some GARCH and stochastic volatility models are evaluated. It is shown that measurement error causes the autocorrelation function, here for the squared process, to start and remain lower than for the underlying unobserved signal process. The size of the effects are highly dependent on the degree of persistence in the volatility. Finally, the consequences of measurement errors on time-varying VaR measures are studied.
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| 13. |
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| 14. |
- Boberg, Elin, 1980-, et al.
(författare)
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Pollinator shifts and the evolution of spur length in the moth-pollinated orchid Platanthera bifolia
- 2014
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 113:2, s. 267-275
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Tidskriftsartikel (refereegranskat)abstract
- Plantpollinator interactions are thought to have shaped much of floral evolution. Yet the relative importance of pollinator shifts and coevolutionary interactions for among-population variation in floral traits in animal-pollinated species is poorly known. This study examined the adaptive significance of spur length in the moth-pollinated orchid Platanthera bifolia. Geographical variation in the length of the floral spur of P. bifolia was documented in relation to variation in the pollinator fauna across Scandinavia, and a reciprocal translocation experiment was conducted in south-east Sweden between a long-spurred woodland population and a short-spurred grassland population. Spur length and pollinator fauna varied among regions and habitats, and spur length was positively correlated with the proboscis length of local pollinators. In the reciprocal translocation experiment, long-spurred woodland plants had higher pollination success than short-spurred grassland plants at the woodland site, while no significant difference was observed at the grassland site. The results are consistent with the hypothesis that optimal floral phenotype varies with the morphology of the local pollinators, and that the evolution of spur length in P. bifolia has been largely driven by pollinator shifts.
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| 15. |
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| 16. |
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| 17. |
- Chen, Qing, et al.
(författare)
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On Negative Diagonal Elements in the Diffusion Coefficient Matrix of Multicomponent Systems
- 2018
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Ingår i: JOURNAL OF PHASE EQUILIBRIA AND DIFFUSION. - : Springer. - 1547-7037 .- 1863-7345. ; 39:5, s. 592-596
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Tidskriftsartikel (refereegranskat)abstract
- In multicomponent systems the diffusion coefficient turns into a matrix. The diagonal elements represent diffusion of a species caused by its own concentration gradient. In a thermodynamically stable binary alloy it is easy to see that this diagonal element must be positive but in a multicomponent system it is less obvious. The sign of the diagonal elements in the general case is discussed in this report. It is shown that the sign of an individual diagonal element has no physical meaning but can be changed by changing the dependent concentration variable. Only the sum of all the diagonal elements need to be positive in a stable system.
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| 18. |
- Dakhel, Ardwan, et al.
(författare)
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Novel cardiovascular biomarkers associated with peripheral arterial disease in men screened for abdominal aortic aneurysm
- 2022
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Ingår i: Vasa - European Journal of Vascular Medicine. - : Hogrefe Publishing Group. - 0301-1526. ; 51:3, s. 167-173
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Tidskriftsartikel (refereegranskat)abstract
- Background: Peripheral arterial disease (PAD) is a common atherosclerotic disease with severity ranging from asymptomatic to chronic limb threatening ischemia. The aim of the present cross-sectional study was to identify novel biomarkers associated with PAD. Patients and methods: Levels of 91 cardiovascular specific proteins in plasma samples were measured by the Proseek Multiplex CVD III96x96 panel from a cohort consisting of 267 65-year-old men recruited from a screening program for abdominal aortic aneurysm (AAA) Levels of protein biomarkers were compared in men with and without PAD (defined as an ankle brachial index of <0.9) and their diagnostic potential was calculated by receiver-operating characteristic analysis. Results: The prevalence of PAD was 14.2% (38/267). After adjustment for multiple comparisons, levels of the following 11 biomarkers remained significantly higher (p<0.0001) in patients with PAD: secretoglobin family 3A member 2, osteoprotegerin, urokinase-type plasminogen activator surface receptor, serum macrophage chemokine ligand 16, matrix metalloproteinase 9, p-selectin, growth differentiation factor 15, elafin, cystatin B, trefoil factor 3, and fatty acid-binding protein 4. Multivariable logistic regression analysis (adjusted for smoking, use of antihypertensive and lipid-lowering medication, and metformin) showed that 11 biomarkers were significantly associated with higher risk of PAD with odds ratios ranging from 1.6 to 2.4. Area under curve calculated by receiver operating characteristic curve analysis (diagnostic value) for each protein biomarker ranged from 0.63 to 0.74. Conclusions: We have identified multiple proteins with a potential to be diagnostic biomarkers for PAD, and further research is warranted to clarify their potential predictive and prognostic value.
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| 19. |
- Ecke, Frauke, et al.
(författare)
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Sublethal Lead Exposure Alters Movement Behavior in Free-Ranging Golden Eagles
- 2017
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Ingår i: Environmental Science and Technology. - : American Chemical Society (ACS). - 0013-936X .- 1520-5851. ; 51:10, s. 5729-5736
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Tidskriftsartikel (refereegranskat)abstract
- Lead poisoning of animals due to ingestion of fragments from lead-based ammunition in carcasses and offal of shot wildlife is acknowledged globally and raises great concerns about potential behavioral effects leading to increased mortality risks. Lead levels in blood were correlated with progress of the moose hunting season. Based on analyses of tracking data, we found that even sublethal lead concentrations in blood (25 ppb, wet weight), can likely negatively affect movement behavior (flight height and movement rate) of free ranging scavenging Golden Eagles (Aquila chrysaetos). Lead levels in liver of recovered post-mortem analyzed eagles suggested that sublethal exposure increases the risk of mortality in eagles. Such adverse effects on animals are probably common worldwide and across species, where game hunting with lead-based ammunition is widespread. Our study highlights lead exposure as a considerably more serious threat to wildlife conservation than previously realized and suggests implementation of bans of lead ammunition for hunting.
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| 20. |
- Engfeldt, Andreas, et al.
(författare)
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RG 2000 – the New Gravity Reference Frame of Sweden
- 2019
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Ingår i: Geophysica. - : Geophysical Society of Finland. - 0367-4231 .- 2324-0741. ; 54:1, s. 69-92
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Tidskriftsartikel (refereegranskat)abstract
- The increased need for improved geoid models for Global Navigation Satellite Systems (GNSS) height determination calls for additional gravity observations and quality assurance of existing data. In this perspective, a modern gravity system and the renovation of an already existing high order gravity network is considered as a moderate strategic investment which provides a firm foundation for further activities. Here the new gravity reference frame RG 2000 for Sweden is presented. RG 2000 is realized by absolute gravity observations at 109 stations. The absolute points are connected via old and new relative gravity observations, including another 216 points. Points and observations have been chosen so that good overlap with the older Swedish reference frames, RG 62 and RG 82, is achieved, allowing to evaluate the older frames and transformations between them. RG 2000 is based on a zero permanent tide system with epoch 2000.
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| 21. |
- Engström, Anders, et al.
(författare)
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COMPUTER-SIMULATION OF DIFFUSION IN MULTIPHASE SYSTEMS
- 1994
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Ingår i: Metallurgical and Materials Transactions. A. - 1073-5623 .- 1543-1940. ; 25:6, s. 1127-1134
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Tidskriftsartikel (refereegranskat)abstract
- A general model to treat multicomponent diffusion in multiphase dispersions is presented. The model is based on multicomponent diffusion data and basic thermodynamic data and contains no adjustable parameters. No restriction is placed on the number of components or phases that take part in the calculations, as long as the necessary thermodynamic and kinetic data are available. The new model is implemented into the DICTRA software, which makes use of THERMO-CALC to handle the thermodynamics. The model is applied to carburization of Ni alloys and heat treatment of welded joints between dissimilar materials. In both cases, the diffusion is accompanied by carbide formation or dissolution. A good agreement between experiments and calculations is found, despite the fact that no adjustable parameters are needed.
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| 22. |
- Eriksson, Olle, et al.
(författare)
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Mood changes correlate to changes in brain serotonin precursor trapping in women with premenstrual dysphoria.
- 2006
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Ingår i: Psychiatry research. - : Elsevier BV. - 0165-1781 .- 0925-4927 .- 1872-7506. ; 146:2, s. 107-16
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Tidskriftsartikel (refereegranskat)abstract
- The cardinal mood symptoms of premenstrual dysphoria can be effectively treated by serotonin-augmenting drugs. The aim of the study was to test the serotonin hypothesis of this disorder, i.e. of an association between premenstrual decline in brain serotonin function and concomitant worsening of self-rated cardinal mood symptoms. Positron emission tomography was used to assess changes in brain trapping of 11C-labeled 5-hydroxytryptophan, the immediate precursor of serotonin, in the follicular and premenstrual phases of the menstrual cycle in eight women with premenstrual dysphoria. Changes in mood and physical symptoms were assessed from daily visual analog scale ratings. Worsening of cardinal mood symptoms showed significant inverse associations with changes in brain serotonin precursor trapping; for the symptom "irritable", r(s)=-0.83, and for "depressed mood" r(s)=-0.81. Positive mood variables showed positive associations, whereas physical symptoms generally displayed weak or no associations. The data indicate strong inverse associations between worsening of cardinal symptoms of premenstrual dysphoria and brain serotonin precursor (11C-labeled 5-hydroxytryptophan) trapping. The results may in part support a role for serotonin in premenstrual dysphoria and may provide a clue to the effectiveness of serotonin-augmenting drugs in this disorder but should, due to small sample size and methodological shortcomings, be considered preliminary.
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| 23. |
- Eriksson, Olle, 1954-, et al.
(författare)
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Women with Premenstrual Dysphoria Lack the Seemingly Normal Premenstrual Right-Sided Relative Dominance of 5-HTP-Derived Serotonergic Activity in the Dorsolateral Prefrontal Cortices - A Possible Cause of Disabling Mood Symptoms.
- 2016
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- To investigate potential quantitative and qualitative differences in brain serotonergic activity between women with Premenstrual Dysphoria (PMD) and asymptomatic controls.Serotonin-augmenting drugs alleviate premenstrual mood symptoms in the majority of women with PMD while serotonin-depleting diets worsen PMD symptoms, both indicating intrinsic differences in brain serotonergic activity in women with PMD compared to asymptomatic women.Positron-emission tomography with the immediate precursor of serotonin, 5-hydroxytryptophan (5-HTP), radiolabelled by 11C in the beta-3 position, was performed in the follicular and luteal phases for 12 women with PMD and 8 control women. Brain radioactivity-a proxy for serotonin precursor uptake and synthesis-was measured in 9 regions of interest (ROIs): the right and left sides of the medial prefrontal cortex, dorsolateral prefrontal cortex, putamen and caudate nucleus, and the single "whole brain".There were no significant quantitative differences in brain 5-HTP-derived activity between the groups in either of the menstrual phases for any of the 9 ROIs. However, multivariate analysis revealed a significant quantitative and qualitative difference between the groups. Asymptomatic control women showed a premenstrual right sided relative increase in dorsolateral prefrontal cortex 5-HTP derived activity, whereas PMD women displayed the opposite (p = 0.0001). Menstrual phase changes in this asymmetry (premenstrual-follicular) correlated with changes in self ratings of 'irritability' for the entire group (rs = -0.595, p = 0.006). The PMD group showed a strong inverse correlation between phase changes (premenstrual-follicular) in plasma levels of estradiol and phase changes in the laterality (dx/sin) of radiotracer activity in the dorsolateral prefrontal ROI (rs = -0.635; 0.027). The control group showed no such correlation.Absence of increased premenstrual right-sided relative 5-HTP-derived activity of the dorsolateral prefrontal cortices was found to strongly correlate to premenstrual irritability. A causal relationship here seems plausible, and the findings give further support to an underlying frontal brain disturbance in hormonally influenced serotonergic activity in women with PMD. Because of the small number of subjects in the study, these results should be considered preliminary, requiring verification in larger studies.
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| 24. |
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| 25. |
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| 26. |
- Florén, Anders, et al.
(författare)
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Historiska undersökningar : Grunder i historisk teori, metod och framställnigssätt
- 2018. - 3
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Bok (övrigt vetenskapligt/konstnärligt)abstract
- Historiska undersökningar handlar om hur man skriver historia,hur händelser i det förflutna ordnas till ett gripbart sammanhang.Den historiska undersökningen är inte vilken text som helst, den syftar till att besvara en fråga. Men hur ska en sådan fråga formuleras? Och hur ska den försvaras?Författarna resonerar här om hur en historievetenskaplig argumentation ser ut, vilka krav som ställs på framställningssättet,hur man använder metoder och källor, samt vad man ska tänka på då man kritiserar ett vetenskapligt arbete. I boken finns också en användbar begreppsguide där aktuella historieteoretiska begrepp och termer beskrivs.Denna tredje upplaga är grundligt reviderad och aktualiserad.Boken vänder sig främst till studenter på grundläggande nivå i historia, som för första gången ställs inför uppgiften att självständigt göra en historisk undersökning.
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| 27. |
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| 28. |
- Florén, Anders, et al.
(författare)
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Swedish Iron Before 1900
- 1993
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Ingår i: Ironmaking in Sweden and Russia. - Uppsala : Historiska institutionen, Uppsala universitet. - 9150609610 ; , s. 7-42
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Bokkapitel (övrigt vetenskapligt/konstnärligt)
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| 29. |
- Garcia, Maria-José
(författare)
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Engineering rubber bushing stiffness formulas including dynamic amplitude dependence
- 2006
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Engineering design models for the torsion and axial dynamic stiffness of carbon black filled rubber bushings in the frequency domain including amplitude dependence are presented. They are founded on a developed material model which is the result of applying a separable elastic, viscoelastic and friction rubber component model to the material level. Moreover, the rubber model is applied to equivalent strains of the strain states inside the torsion or axial deformed bushing previously obtained by the classical linear theory of elasticity, thus yielding equivalent shear moduli which are inserted into analytical formulas for the stiffness. Therefore, unlike other simplified approaches, this procedure includes the Fletcher-Gent effect inside the bushing due to non-homogeneous strain states. The models are implemented in Matlab®. In addition, an experimental verification is carried out on a commercially available bushing thus confirming the accuracy of these models which become a fast engineering tool to design the most suitable rubber bushing to fulfil user requirements. Finally, they can be easily employed in multi-body and finite element simulations
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| 30. |
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| 31. |
- Goude, Anders
(författare)
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Fluid Mechanics of Vertical Axis Turbines : Simulations and Model Development
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Two computationally fast fluid mechanical models for vertical axis turbines are the streamtube and the vortex model. The streamtube model is the fastest, allowing three-dimensional modeling of the turbine, but lacks a proper time-dependent description of the flow through the turbine. The vortex model used is two-dimensional, but gives a more complete time-dependent description of the flow. Effects of a velocity profile and the inclusion of struts have been investigated with the streamtube model. Simulations with an inhomogeneous velocity profile predict that the power coefficient of a vertical axis turbine is relatively insensitive to the velocity profile. For the struts, structural mechanic loads have been computed and the calculations show that if turbines are designed for high flow velocities, additional struts are required, reducing the efficiency for lower flow velocities.Turbines in channels and turbine arrays have been studied with the vortex model. The channel study shows that smaller channels give higher power coefficients and convergence is obtained in fewer time steps. Simulations on a turbine array were performed on five turbines in a row and in a zigzag configuration, where better performance is predicted for the row configuration. The row configuration was extended to ten turbines and it has been shown that the turbine spacing needs to be increased if the misalignment in flow direction is large.A control system for the turbine with only the rotational velocity as input has been studied using the vortex model coupled with an electrical model. According to simulations, this system can obtain power coefficients close to the theoretical peak values. This control system study has been extended to a turbine farm. Individual control of each turbine has been compared to a less costly control system where all turbines are connected to a mutual DC bus through passive rectifiers. The individual control performs best for aerodynamically independent turbines, but for aerodynamically coupled turbines, the results show that a mutual DC bus can be a viable option.Finally, an implementation of the fast multipole method has been made on a graphics processing unit (GPU) and the performance gain from this platform is demonstrated.
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| 32. |
- Goude, Anders, et al.
(författare)
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Numerical Simulation of a Farm of Vertical Axis Marine Current Turbines
- 2010
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Ingår i: PROCEEDINGS OF THE ASME 29TH INTERNATIONAL CONFERENCE ON OCEAN, OFFSHORE AND ARCTIC ENGINEERING 2010, VOL 3. - 9780791849118 ; , s. 335-344
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Konferensbidrag (refereegranskat)abstract
- For commercial applications of marine current turbines, it can be useful to build several turbines close to each other in a farm, similar to wind turbine parks. To create a good farm configuration, the turbines' mutual interaction needs to be studied. Here, to obtain detailed information, several turbines were simulated together using a 2D vortex method. To limit the computational cost, the vortex method was combined with known profile section data for the blades.First, a single turbine was compared against two turbines in close proximity. The two turbines were tested both with equal and opposite rotational direction, and the two blade pitch angles 0 and 3 degrees were tested. For both a single turbine and the two turbine case, a 3 degree pitch angle gave higher power coefficients than 0 degrees. The differences between 3 and 0 degrees were more significant for the single turbine. In all cases, the two turbine system had higher power coefficient per turbine than the single turbine.A five turbine park was simulated with three different combinations, one with all turbines on a row, and two with a zigzag pattern, where the difference was that the last simulation had larger turbines than the other two. For 0 degrees incident flow angle, the turbines on the row obtained the highest power coefficient, while the larger turbines in zigzag pattern obtained higher total power. The case with the turbines on the row was most insensitive to changes in flow direction, and for a 30 degree change, the row produced the highest total power as well. By locating the turbines inside a channel, all turbines obtained higher power coefficients, and the increase was largest for the large turbines, which blocked the channel to a larger extent.
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| 33. |
- Goude, Anders, et al.
(författare)
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Simulations of a vertical axis turbine in a channel
- 2014
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Ingår i: Renewable energy. - : Elsevier. - 0960-1481 .- 1879-0682. ; 63, s. 477-485
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Tidskriftsartikel (refereegranskat)abstract
- The power coefficient of a turbine increases according to the predictions from streamtube theory for sites with a confined fluid flow. Here, a vertical axis turbine (optimized for free flow) has been simulated by a two-dimensional vortex method, both in a channel and in free flow. The first part of the study concerns the numerical parameters of channel simulations. It is found that for free flow and wide channels, a large number of revolutions is required for convergence (around 100 at the optimal tip speed ratio and increasing with higher tip speed ratio), while for smaller channels, the required number of revolutions decreases. The second part analyses changes in turbine performance by the channel boundaries. The turbine performance increases when the channel width is decreased, although the results are below the predictions from streamtube theory, and this difference increases with decreasing channel width. It is also observed that the optimal tip speed ratio increases with decreasing channel width. By increasing the chord, which decreases the optimal tip speed ratio, the power coefficient can be increased somewhat.
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| 34. |
- Grane, Camilla, et al.
(författare)
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Project: EFESOS - Environmental Friendly efficient Enjoyable and Safety Optimized Systems
- 2012
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Annan publikation (populärvet., debatt m.m.)abstract
- EFESOS is a Swedish Vehicle HMI (Human Machine Interaction) FFI research project. The overall ambition is to make driving of future cars more environmental friendly, enjoyable and safer by means of optimized systems. The project is managed by Volvo Car Corporation (VCC) and it is a collaboration between VCC and seven other research partners including Luleå University of Technology.
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| 35. |
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| 36. |
- Hagnestål, Anders, et al.
(författare)
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A Compact Non-Planar Coil Design for the SFLM Hybrid
- 2012
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 31:4, s. 379-388
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Tidskriftsartikel (refereegranskat)abstract
- A non-planar single layer semiconductor coil set for a version of the Straight Field Line Mirror Hybrid concept with reduced magnetic field has been computed. The coil set consists of 30 coils that are somewhat similar to baseball coils with skewed sides. The coil set has been modeled with filamentary current distributions and basic scaling assumptions have been made regarding the coil widths. This coil set is expected to be considerably cheaper than a previous computed coil set. The coils can probably be produced with technologies known today.
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| 37. |
- Hagnestål, Anders, et al.
(författare)
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A study on field and coil designing for a quadrupolar mirror hybrid reactor
- 2011
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Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 30:2, s. 144-156
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Tidskriftsartikel (refereegranskat)abstract
- A vacuum magnetic field from a superconducting coil set for a single cell minimum B fusion-fission mirror machine reactor is computed. The magnetic field is first optimized for MHD flute stability, ellipticity and field smoothness in a long-thin approximation. Recirculation regions and magnetic expanders are added to the mirror machine without an optimizing procedure. The optimized field is thereafter reproduced by a set of circular and quadrupolar coils. The coils are modelled using filamentary line current distributions. Basic scaling assumptions are implemented for the coil design, with a maximum allowed current density of 1.5 kA/cm2. The coils are optimized using a local optimization method and the resulting field is checked for MHD flute stability and maximum ellipticity.
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| 38. |
- Hagnestål, Anders, 1976-
(författare)
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Coil Design and Related Studies for the Fusion-Fission Reactor Concept SFLM Hybrid
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- A fusion-fission (hybrid) reactor is a combination of a fusion device and a subcritical fission reactor, where the fusion device acts as a neutron source and the power is mainly produced in the fission core. Hybrid reactors may be suitable for transmutation of transuranic isotopes in the spent nuclear fuel, due to the safety margin on criticality imposed by the subcritical fission core. The SFLM Hybrid project is a theoretical project that aims to point out the possibilities with steady-state mirror-based hybrid reactors. The quadrupolar magnetic mirror vacuum field is based on the Straight Field Line Mirror field and the central cell is 25 m long. A fission mantle surrounds the mirror cell. The fission to fusion power ratio is about 150 with keff = 0.97, implying that almost all the produced energy comes from fission. Beyond each mirror end magnetic expanders are located, which increase the plasma receiving “divertor” area and provide tolerable heat load on wall materials. The plasma is heated with ion cyclotron radio frequency heating and the fission mantle is cooled using a liquid lead-bismuth eutectic. The device is self-sufficient in tritium, and does not seem to suffer from severe material problems. A remaining issue may be the plasma electron temperature, which need to reach about 500 eV for efficient power production. In this doctoral thesis, theoretical work has been done with the magnetic coil system of such a device and also with the overall concept. A new coil type, the fishbone coil, suitable for single cell quadrupolar mirrors, has been invented. Two vacuum field coil sets with satisfying properties have been found, where the most recent coil set consists of fishbone coils. Finite ß effects on the magnetic field have been investigated, showing that the flux tube ellipticity increases with ß. The ellipticity of the vacuum field increases slightly with radius, but with finite ß it decreases with radius. The maximum flux surface radial extensions decrease with ß, which is an unexpected and beneficial result. A radial invariant has also been identified, and particle simulations have been made to emphasize that quadrupolar mirrors must be symmetric or confinement may be lost.
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| 39. |
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| 40. |
- Hagnestål, Anders, et al.
(författare)
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Coil design for the straight field line mirror
- 2009
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Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 55:2T, s. 127-130
-
Tidskriftsartikel (refereegranskat)abstract
- Coil systems for producing the Straight Field Line Mirror field using axisymmetric and quadrupolar coils are calculated. Two applications are intended, a fusion-fission nuclear waste transmutation device and a small plasma deposition device. Position, size and current for the axisymmetric coils are optimized as well as radial profile and current for the quadrupolar coils for the two applications. Calculations show that such a coil system can produce the Straight Field Line Mirror field for long-thin mirrors with moderate mirror ratio, but some other coil configuration needs to be found for mirrors where the coils cannot reside close to the plasma edge. In this work, the material science experiment mirror can be produced with about 1% error but the fusion-fission device field has not at this moment been reproduced with acceptable errors.
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| 41. |
- Hagnestål, Anders, et al.
(författare)
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Coil System For a Mirror-Based Hybrid Reactor
- 2012
-
Ingår i: Fusion for Neutrons and Subcritical Nuclear Fission. - : AIP. - 9780735410381 ; , s. 217-223
-
Konferensbidrag (refereegranskat)abstract
- Two different superconducting coil systems for the SFLM Hybrid study - a quadrupolar mirror based fusion-fission reactor study - are presented. One coil system is for a magnetic field with 2 T at the midplane and a mirror ratio of four. This coil set consists of semi-planar coils in two layers. The alternative coil system is for a downscaled magnetic field of 1.25 T at the midplane and a mirror ratio of four, where a higher beta is required to achieve sufficient the neutron production. This coil set has one layer of twisted 3D coils. The 3D coils are expected to be considerably cheaper than the semiplanar, since NbTi superconductors can be used for most coils instead of Nb3Sn due to the lower magnetic field.
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| 42. |
- Hagnestål, Anders, et al.
(författare)
-
Field and Coil Design for a Quadrupolar Mirror Hybrid Reactor
- 2011
-
Ingår i: Journal of fusion energy. - : Springer Science and Business Media LLC. - 0164-0313 .- 1572-9591. ; 30:2, s. 144-156
-
Tidskriftsartikel (refereegranskat)abstract
- A vacuum magnetic field from a superconducting coil set for a single cell minimum B fusion-fission mirror machine reactor is computed. The magnetic field is first optimized for MHD flute stability, ellipticity and field smoothness in a long-thin approximation. Recirculation regions and magnetic expanders are added to the mirror machine without an optimizing procedure. The optimized field is thereafter reproduced by a set of circular and quadrupolar coils. The coils are modelled using filamentary line current distributions. Basic scaling assumptions are implemented for the coil design, with a maximum allowed current density of 1.5 kA/cm(2). The coils are optimized using a local optimization method and the resulting field is checked for MHD flute stability and maximum ellipticity.
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| 43. |
- Hagnestål, Anders, 1976-, et al.
(författare)
-
Finite ß corrections to the magnetic field in the SFLM Hybrid
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Finite effects for the magnetic field in the SFLM Hybrid reactor concept have been studied numerically. The parallel current has been calculated, and it is found to be negligible. The constant pressure surfaces at the midplane are not significantly affected by the parallel current, and have a square-like octupolar distortion near the plasma edge. In most of the plasma region, their cross sections are nearly circular. The flux tube ellipticity is found to increase by the finite effects, but the increase is considerably more pronounced near the z axis where the pressure is high. At the plasma edge, the increase in ellipticity by finite effects is only moderate and the maximum radial extensions of the flux tube are even slightly decreased compared to the vacuum case.
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| 44. |
- Hagnestål, Anders, et al.
(författare)
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Radial Confinement in Non-Symmetric Quadrupolar Mirrors
- 2013
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Ingår i: Journal of fusion energy. - : Springer. - 0164-0313 .- 1572-9591. ; 32:3, s. 327-335
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Tidskriftsartikel (refereegranskat)abstract
- Charged particles in symmetric quadrupolar mirrors are radially confined and have an associated radial invariant. In a symmetric quadrupolar field the magnetic field modulus satisfies B(z)=−B(z) along the axis if z = 0 defines the field minimum of the mirror, and the quadrupolar field has a corresponding symmetry. The field in the anchor cells of a tandem mirror need not obey a corresponding symmetry. In this paper, the radial confinement of non-symmetric mirrors is examined by tracing sample ions in the magnetic field. It is found that for non-symmetric mirrors, particles are typically not confined, and no radial invariant exists for such devices. Without attention to this effect in the field and coil design, radial confinement of trapped particles may be lost.
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| 45. |
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| 46. |
- Hagnestål, Anders, et al.
(författare)
-
Theoretical field and coil design for a single cell minimum-B mirror hybrid reactor
- 2011
-
Ingår i: Fusion science and technology. - 1536-1055 .- 1943-7641. ; 59:1T, s. 217-219
-
Tidskriftsartikel (refereegranskat)abstract
- A vacuum magnetic field from a superconducting coil set for a single cell minimum-B mirror-based,fission-fusion reactor is computed. The magnetic field is optimized for MHD stability, ellipticity and field smoothness. A recirculation region and wide magnetic expanders on both sides are provided to the central mirror cell. A coil set producing this field is computed which consists of circular and quadrupolar coils. Basic scaling assumptions are made for the coil dimensions, based on a maximum allowed current density of 1.5 kA/cm(2) for superconducting coils. Sufficient space is available for a fission mantle. The field produced by the coils is checked for MHD plasma stability and maximum ellipticity. The resulting confinement region is 25 in long with a 40 cm midplane plasma radius.
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| 47. |
- Hagnestål, Anders, et al.
(författare)
-
Vacuum Field Ellipticity Dependence on Radius in Quadrupolar Mirror Machines
- 2012
-
Ingår i: Journal of fusion energy. - : Springer Netherlands. - 0164-0313 .- 1572-9591. ; 31:5, s. 448-454
-
Tidskriftsartikel (refereegranskat)abstract
- The vacuum field flux tube ellipticity dependence on radius for quadrupolar mirror machines has been investigated. A third order expression in the paraxial approximation has been derived for the vacuum field ellipticity. The dependence of ellipticity on midplane radius has been examined in the SFLM Hybrid and the outermost plasma flux tube is 3.5 cm wider than predicted by the first order paraxial approximation, which is within boundaries set by the first wall. The third order approximation has a high accuracy for the ellipticity for long-thin mirrors such as the SFLM Hybrid, and even the first order approximation that is independent of radius is sufficient in many applications. The ellipticity dependence on midplane radius for mirrors with more strongly localized quadrupolar fields than the SFLM Hybrid is also shown to be minor.
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| 48. |
- Helander, Björn, 1946-, et al.
(författare)
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Major lead exposure from hunting ammunition in eagles from Sweden
- 2021
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Ingår i: Science of the Total Environment. - : Elsevier BV. - 0048-9697 .- 1879-1026. ; , s. 1-16
-
Tidskriftsartikel (refereegranskat)abstract
- Exposure to lead (Pb) from ammunition in scavenging and raptorial birds has achieved worldwide recognition based on incidences of lethal poisoning, but exposure implies also sublethal levels with potential harmful effects.Background and elevated Pb levels in liver from 116 golden eagles (GE, Aquila chrysaetos) and 200 white-tailed sea eagles (WTSE, Haliaeetus albicilla) from Sweden 2003–2011 are here examined, with supporting data from a previous WTSE report and eagle owl (EO, Bubu bubo) report. GE and WTSE display seasonal patterns, with no Pb level exceeding a generally accepted threshold for subclinical effects during summer but strongly elevated levels from October. Fledged juveniles show significantly lower levels than all other age classes, but reach levels found in older birds in autumn after the start of hunting seasons. Pb levels in EO (non-scavenger) show no seasonal changes and indicate no influence from ammunition, and are close to levels observed in juvenile eagles before October. In all, 15% WTSE and 7% GE were lethally poisoned. In areas with high-exposure to hunting ammunition, 24% of WTSE showed lethal Pb levels, compared to 7% in both eagle species from low-exposure areas. Lethal poisoning of WTSE remained as frequent after (15%) as before (13%) a partial ban on use of Pb-based shotgun ammunition over shallow waters (2002). Pb levels increased significantly in WTSE 1981–2011,in contrast to other biota from the same period. A significant decrease of Pb in WTSE liver occurred below a threshold at 0.25 μg/g (dry weight), exceeded by 81% of the birds. Trend patterns in Pb isotope ratios lend further support to this estimated cut-off level for environmental background concentrations. Pb from spent ammunition affects a range of scavenging and predatory species. A shift to Pb-free ammunition to save wildlife from unnecessary harm is an important environmental and ethical issue.
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| 49. |
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| 50. |
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