| 1. |
- Andersson, Emelie, et al.
(författare)
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Disease burden and unmet need for acute allergic reactions - A patient perspective
- 2024
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Ingår i: World Allergy Organization Journal. - : Elsevier. - 1939-4551. ; 17:4
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Tidskriftsartikel (refereegranskat)abstract
- Background: Acute allergic reactions (AARs) occur shortly after exposure to an allergen, and the severity is on a continuum. Systemic corticosteroids (CS) are mainstay treatment of moderate to severe AARs, whereas those at risk of the most severe AARs (ie, anaphylaxis) are also recommended prescription of epinephrine autoinjectors. There is limited research on the impact of AARs not fulfilling the criteria for anaphylaxis. We have characterized a sample with a history of moderate to severe AARs and evaluated their self-reported disease burden (ie, daily life impact, anxiety, and treatment impediments).Methods: Survey study of adults with experience of AARs treated with CS. Participants recruited from a web-based panel and using social media were asked to complete a questionnaire related to their allergy and experience of AARs. The results were summarized for the whole sample and across subgroups with and without prescription of epinephrine.Results: The final study sample included 387 participants (80% women, mean age 41), of which 129 (33%) had at some point been prescribed epinephrine. The most common symptoms were respiratory (80%) and skin (78%) manifestations, and the mean (standard deviation, SD) self-rated severity score (scale from 0 [very mild] to 10 [very severe]) of the most recent AAR was 6.1 (2.0). More than 80% had experience of AARs interrupting daily activities and 50% of AARs that had limited work/studies or participation in leisure activities. Most of the respondents reported some degree of anxiety related to AARs and 43% had feared for their lives. Moreover, difficulties swallowing allergy medicine at an AAR was experienced by 26% and not having the medicine available when needed by 66%. Participants with prescription of epinephrine experienced more severe AARs than those without such prescription (mean [SD] severity 6.8 [2.1] vs 5.8 [1.8], p < 0.0001); however, also those without epinephrine prescription reported considerable anxiety and impact on daily life and to a similar degree as those with prescription.Conclusions: In this sample, subjects with experience of AARs treated with CS showed a considerable disease burden with anxiety and interruption on daily life, as well as problems related to access to, and swallowing of, medication. Although respondents with epinephrine prescription had more severe disease, a high disease burden was also evident among those without epinephrine. The study increases the knowledge of people with moderate to severe AARs, a patient population that has previously been underrepresented in the research literature.
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| 2. |
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| 3. |
- Bijl, Wouter, et al.
(författare)
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Butterfly dichromatism primarily evolved via Darwin's, not Wallace's, model
- 2020
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Ingår i: Evolution letters. - : Oxford University Press (OUP). - 2056-3744. ; 4:6, s. 545-555
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Tidskriftsartikel (refereegranskat)abstract
- Sexual dimorphism is typically thought to result from sexual selection for elaborated male traits, as proposed by Darwin. However, natural selection could reduce expression of elaborated traits in females, as proposed by Wallace. Darwin and Wallace debated the origins of dichromatism in birds and butterflies, and although evidence in birds is roughly equal, if not in favor of Wallace's model, butterflies lack a similar scale of study. Here, we present a large‐scale comparative phylogenetic analysis of the evolution of butterfly coloration, using all European non‐hesperiid butterfly species (n = 369). We modeled evolutionary changes in coloration for each species and sex along their phylogeny, thereby estimating the rate and direction of evolution in three‐dimensional color space using a novel implementation of phylogenetic ridge regression. We show that male coloration evolved faster than female coloration, especially in strongly dichromatic clades, with male contribution to changes in dichromatism roughly twice that of females. These patterns are consistent with a classic Darwinian model of dichromatism via sexual selection on male coloration, suggesting this model was the dominant driver of dichromatism in European butterflies.
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| 4. |
- Brunetti, D., et al.
(författare)
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Analytic stability criteria for edge MHD oscillations in high performance ELM free tokamak regimes
- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 58:1
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Tidskriftsartikel (refereegranskat)abstract
- A new dispersion relation, and associated stability criteria, is derived for low-n external kink and infernal modes, and is applied to modelling the stability properties of quiescent H-mode like regimes. The analysis, performed in toroidal geometry with large edge pressure gradients associated with a local flattening of the safety factor, includes a pedestal, sheared toroidal rotation and a vacuum region separating the plasma from an ideal metallic wall. The external kink-infernal modes found here exhibit similarities with experimentally observed edge harmonic oscillations.
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| 5. |
- Brunetti, Daniele, et al.
(författare)
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Analytic study on low-n external ideal infernal modes in tokamaks with large edge pressure gradients
- 2018
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Ingår i: Journal of Plasma Physics. - 0022-3778 .- 1469-7807. ; 84:2
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Tidskriftsartikel (refereegranskat)abstract
- The problem of pressure driven infernal type perturbations near the plasma edge is addressed analytically for a circular limited tokamak configuration which presents an edge flattened safety factor. The plasma is separated from a metallic wall, either ideally conducting or resistive, by a vacuum region. The dispersion relation for such types of instabilities is derived and discussed for two classes of equilibrium profiles for pressure and mass density.
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| 6. |
- Brunetti, D., et al.
(författare)
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Anisotropy and shaping effects on the stability boundaries of infernal ideal MHD modes in tokamak hybrid plasmas
- 2020
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 62:11
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Tidskriftsartikel (refereegranskat)abstract
- Anisotropy and some limiting toroidal flow effects on the stability of nearly resonant ideal magnetohydrodynamic modes in hybrid shaped tokamak plasmas are investigated within the ideal MHD infernal mode framework. Such effects are found to alter the plasma magnetic well/hill, which can be interpreted as imparing the average curvature, and the strength of mode coupling. In line with previous results, it is found that better stability properties are achieved through deepening the magnetic well by special cases of uniform toroidal flow and parallel plasma anisotropy. Plasma shaping provides additional modifications to the magnetic well depth, whose global stabilising or destabilising effect depends on the mutual interplay of elongation, triangularity and toroidicity. Further stabilisation is achieved by weakening the mode drive in vertically elongated plasmas.
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| 7. |
- Brunetti, D., et al.
(författare)
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Excitation Mechanism of Low-n Edge Harmonic Oscillations in Edge Localized Mode-Free, High Performance, Tokamak Plasmas
- 2019
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Ingår i: Physical Review Letters. - : AMER PHYSICAL SOC. - 0031-9007 .- 1079-7114. ; 122:15
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Tidskriftsartikel (refereegranskat)abstract
- The excitation mechanism for low-n edge harmonic oscillations in quiescent H-mode regimes is identified analytically. We show that the combined effect of diamagnetic and poloidal magnetohydrodynamic flows, with the constraint of a Doppler-like effect of the ion flow, leads to the stabilization of short wavelength modes, allowing low-n perturbation to grow. The analysis, performed in tokamak toroidal geometry, includes the effects of large edge pressure gradients, associated with the local flattening of the safety factor and diamagnetic flows, sheared parallel and E x B rotation, and a vacuum region between plasma and the ideal metallic wall. The separatrix also is modeled analytically.
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| 8. |
- Brunetti, D., et al.
(författare)
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Helical equilibrium magnetohydrodynamic flow effects on the stability properties of low-n ideal external-infernal modes in weak shear tokamak configurations
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 61:6
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Tidskriftsartikel (refereegranskat)abstract
- The impact of equilibrium helical flows on the stability properties of low shear tokamak plasmas is assessed. The corrections due to such helical flow to the equilibrium profiles (mass density, pressure, Shafranov shift, magnetic fluxes) are computed by minimising order by order the generalised Grad-Shafranov equation. By applying the same minimisation procedure, a set of three coupled equations, suitable for the study of magnetohydrodynamic perturbations localised within core or edge transport barriers is derived in circular tokamak geometry. We apply these equations to modelling the impact of strong poloidal flow shear in the edge region caused by a radial electric field on the stability of edge infernal modes retaining vacuum effects. Due to the poloidal flow shearing, the effect of plasma rotation is not simply a Doppler shift of the eigenfrequency. Stabilisation is found even for weak flow amplitude.
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| 9. |
- Brunetti, D., et al.
(författare)
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Understanding JET-C quiescent phases with edge harmonic magnetohydrodynamic activity and comparison with behaviour under ITER-like wall conditioning
- 2022
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 64:4
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Tidskriftsartikel (refereegranskat)abstract
- An analysis of edge localised mode-free (quiescent) H-mode discharges exhibiting edge harmonic magnetoydrodynamic activity in the JET-carbon wall machine is presented. It is observed that the otherwise quiescent pulses with multiple-n harmonic oscillations are sustained until a threshold in pedestal electron density and collisionality is crossed. The macroscopic pedestal parameters associated with the quiescent phase are compared with those of a database of JET-ELMy discharges with both carbon and ITER-like wall (ILW). This comparison provides the identification of the existence regions in the relevant pedestal and global plasma parameters for edge harmonic oscillations (EHOs) in JET plasmas. Although the ELMy database scans pedestal collisionality and β values typical of ET-carbon quiescent operation, shaping and current are not simultaneously compatible with EHO existence. Nevertheless, ILW operation with JET-carbon quiescent-like parameters could in principle be achieved, and improved pedestal performance could be observed in more recent JET-ILW pulses.
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| 10. |
- Chapman, I. T., et al.
(författare)
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The effect of plasma profile variation on the stability of the n=1 internal kink mode in rotating tokamak plasmas
- 2010
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 50:2, s. 025018-
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Tidskriftsartikel (refereegranskat)abstract
- The sensitivity of the stability of the ideal n = 1 internal kink mode to variations in the plasma profiles is analysed both analytically and numerically in rotating tokamak plasmas. These stability analyses have been carried out including the centrifugal effects of toroidal plasma rotation upon the equilibrium, and also inconsistently when the equilibrium is treated as static. The change in plasma stability due to rotation is partially (consistent equilibrium) or wholly (inconsistent treatment) determined by the radial profiles of the plasma density and rotation velocity. It is found that the internal kink mode stability is strongly influenced by small variations in these plasma profiles. The implications of this extreme sensitivity are discussed, with particular reference to experimental data from MAST.
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| 11. |
- Chapman, I. T., et al.
(författare)
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The effects of sheared toroidal rotation on stability limits in tokamak plasmas
- 2011
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 53:12, s. 125002-
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Tidskriftsartikel (refereegranskat)abstract
- Sheared toroidal rotation is found to increase the ideal external kink stability limit, thought to be the ultimate performance limit in fusion tokamaks. However, at rotation speeds approaching a significant fraction of the Alfven speed, the toroidal rotation shear drives a Kelvin-Helmholtz-like global plasma instability. Optimizing the rotation profile to maximize the pressure before encountering external kink modes, but simultaneously avoiding flow-driven instabilities, can lead to a window of stability that might be attractive for operating future high-performance fusion devices such as a spherical tokamak component test facility.
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| 12. |
- Dinca, Vlad, et al.
(författare)
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Reproductive isolation and patterns of genetic differentiation in a cryptic butterfly species complex
- 2013
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Ingår i: Journal of Evolutionary Biology. - : Wiley. - 1010-061X .- 1420-9101. ; 26:10, s. 2095-2106
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Tidskriftsartikel (refereegranskat)abstract
- Molecular studies of natural populations are often designed to detect and categorize hidden layers of cryptic diversity, and an emerging pattern suggests that cryptic species are more common and more widely distributed than previously thought. However, these studies are often decoupled from ecological and behavioural studies of species divergence. Thus, the mechanisms by which the cryptic diversity is distributed and maintained across large spatial scales are often unknown. In 1988, it was discovered that the common Eurasian Wood White butterfly consisted of two species (Leptidea sinapis and Leptidea reali), and the pair became an emerging model for the study of speciation and chromosomal evolution. In 2011, the existence of a third cryptic species (Leptidea juvernica) was proposed. This unexpected discovery raises questions about the mechanisms preventing gene flow and about the potential existence of additional species hidden in the complex. Here, we compare patterns of genetic divergence across western Eurasia in an extensive data set of mitochondrial and nuclear DNA sequences with behavioural data on inter- and intraspecific reproductive isolation in courtship experiments. We show that three species exist in accordance with both the phylogenetic and biological species concepts and that additional hidden diversity is unlikely to occur in Europe. The Leptidea species are now the best studied cryptic complex of butterflies in Europe and a promising model system for understanding the formation of cryptic species and the roles of local processes, colonization patterns and heterospecific interactions for ecological and evolutionary divergence.
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| 13. |
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| 14. |
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| 15. |
- Friberg, Magne, et al.
(författare)
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Genetic differentiation and phylogeographic patterns in European populations of Leptidea sinapis and L. reali
-
Annan publikation (refereegranskat)abstract
- The direction of a coevolutionary interaction can differ between local populations as in the butterflies Leptidea sinapis and L. reali. The morphologically virtually identical sister-species have partitioned their niches differently in different parts of their distribution by shifting habitat specialist and generalist roles between different sympatric areas. Hence, a species that is a generalist in some areas can be a local specialist in others, and vice versa. We have sequenced the mitochondrial COI gene from specimens collected across Europe in order to (i) describe the between-species variation over a large area, (ii) identify possible glacial refugia and re-colonisation routes to obtain a phylogeographic hypothesis for explaining the geographic mosaic of niche separation and (iii) apply a population genetic approach to determine the level of intraspecific genetic differentiation. The results show evidence for species distinctiveness throughout Europe. Only small variation was found in L. reali, whereas the haplotype network of L. sinapis showed a deep division into two haplotype families of which one was restricted to Spain and the other was widespread over the continent (including Spain). The widespread haplotype family was divided into two common variants, one eastern and one western, each being surrounded by rare haplotypes. The both deep and shallow genetic differentiation implies that L. sinapis might have been divided into different refugia during several glaciations. Both species showed significant genetic differentiation in pairwise ФST, and as habitat generalist populations could differ significantly from other habitat generalist populations but not from habitat specialist populations, we conclude that this study supports that the geographic mosaic of niche separation is caused by local processes rather than common ancestry of local habitat generalists or specialists within each species
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| 16. |
- Friberg, Magne, et al.
(författare)
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Niche separation in space and time between two sympatric sister species—a case of ecological pleiotropy
- 2008
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Ingår i: Evolutionary Ecology. - : Springer Science and Business Media LLC. - 0269-7653 .- 1573-8477.
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Tidskriftsartikel (refereegranskat)abstract
- Abstract We investigate the niche separation in space and time between the Palearctic sister species Leptidea sinapis and L. reali (Lepidoptera, Pieridae) in central Sweden. Using field sampling, we show that L. reali is a habitat specialist confined to meadows, whereas L. sinapis is a habitat generalist also inhabiting forests. This difference in habitat utilization was corroborated by experimental release of laboratory-reared L. sinapis and L. reali in two adjacent forest and meadow habitats during their natural flight period; virtually all recaptured L. reali that were released in the forest were later caught in the meadow, whereas L. sinapis shifted equally often from meadow to forest as in the opposite direction. In the field, both species fly in May–June, but L. reali appears on average a week earlier in spring and has a substantial second generation in July, whereas L. sinapis is practically univoltine. When overwintered pupae were incubated under identical conditions in the laboratory, females did, however, not differ in phenology, and L. sinapis males actually emerged earlier than L. reali males. When larvae were reared at 23°C on the host plant Lotus corniculatus at a range of daylengths, both species produced a substantial proportion of directly developing individuals at an 18.5 h daylength or longer. When reared at 23°C and a 22 h daylength, L. reali showed an overall higher propensity to develop directly than L. sinapis on plant species originating from both the meadow and the forest habitat. Both Leptidea species showed a lower propensity to enter direct development on forest associated plants than on meadow associated plants. Hence, we suggest that the difference in phenology and voltinism between L. sinapis and L. reali is largely the result of environmentally implemented ecological pleiotropic effects caused by the between-species difference in habitat preference.
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| 17. |
- Graves, J. P., et al.
(författare)
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Generalised zonal modes in stationary axisymmetric plasmas
- 2017
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP PUBLISHING LTD. - 0741-3335 .- 1361-6587. ; 59:5
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Tidskriftsartikel (refereegranskat)abstract
- The MHD model enables derivation and analysis of the rich structure of geodesic acoustic modes (GAMs) and zonal modes in axisymmetric magnetic confined plasmas. The modes are identifiable from a single dispersion relation as two branches of slow magnetosonic continua. The lower frequency branch can be identified as a zonal flow (ZF), which in the simplified limit of static plasmas, has vanishing magnetic component. It is shown in this contribution that axisymmetric, and lesser known non-axisymmetric, zonal modes can be derived from MHD and kinetic models. The work provides a comprehensive derivation of the GAMs and ZF continua in stationary toroidally rotating plasmas, and investigates the exact solution and structure of a generalised family of zonal modes in static equilibria.
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| 18. |
- Graves, J. P., et al.
(författare)
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Pressure driven long wavelength MHD instabilities in an axisymmetric toroidal resistive plasma
- 2022
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 64:1
-
Tidskriftsartikel (refereegranskat)abstract
- A general set of equations that govern global resistive interchange, resistive internal kink and resistive infernal modes in a toroidal axisymmetric equilibrium are systematically derived in detail. Tractable equations are developed such that resistive effects on the fundamental rational surface can be treated together with resistive effects on the rational surfaces of the sidebands. Resistivity introduces coupling of pressure driven toroidal instabilities with ion acoustic waves, while compression introduces flute-like flows and damping of instabilities, enhanced by toroidal effects. It is shown under which equilibrium conditions global interchange, internal kink modes or infernal modes occur. The m = 1 internal kink is derived for the first time from higher order infernal mode equations, and new resistive infernal modes resonant at the q = 1 surface are reduced analytically. Of particular interest are the competing effects of resistive corrections on the rational surfaces of the fundamental harmonic and on the sidebands, which in this paper is investigated for standard profiles developed for the m = 1 internal kink problem.
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| 19. |
- Graves, J. P., et al.
(författare)
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Reduced models for parallel magnetic field fluctuations and their impact on pressure gradient driven MHD instabilities in axisymmetric toroidal plasmas
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP PUBLISHING LTD. - 0741-3335 .- 1361-6587. ; 61:10
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Tidskriftsartikel (refereegranskat)abstract
- It is well known that parallel magnetic field fluctuations are connected with finite plasma beta effects. It can therefore be expected that Reduced Models that simplify or neglect the parallel magnetic field may not capture the salient physics of all types of pressure gradient driven instabilities. This is particularly true in axisymmetric toroidal plasmas in which pressure driven MHD instabilities are always associated with toroidicty and the coupling of the poloidal mode harmonics. This contribution examines the distinct role of parallel magnetic field perturbations on short and long wavelength pressure driven MHD instabilities, and investigates quantitatively the impact of reduced electromagnetic models frequently deployed in fluid and gyrokinetic codes.
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| 20. |
- Graves, Jonathan, et al.
(författare)
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Safety factor corrections to the magnetohydrodynamic internal kink mode in a tokamak
- 2007
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 14:8, s. 082504-
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Tidskriftsartikel (refereegranskat)abstract
- It has long been acknowledged that the well known and frequently used stability criterion beta_p < 0.3 for the toroidal ideal magnetohydrodynamic internal kink mode in a tokamak is inaccurate for an empirically relevant safety factor. The present paper outlines the severity of the usual approximation, and presents improved analytical approximations of the general solution in M. N. Bussac, R. Pellat, D. Edery, and J. L. Soulé, Phys. Rev. Lett. 35, 1638 (1975), thus providing new insights into the nature of the instability, together with simple formulas that can be incorporated into transport codes with sawtooth cycle algorithms.
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| 21. |
- Hansson Wahlberg, Tobias, et al.
(författare)
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Dissolving McTaggart's Paradox
- 2013
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Ingår i: Johanssonian Investigations. - 9783868381900 ; 5, s. 240-258
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Bokkapitel (refereegranskat)
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| 22. |
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| 23. |
- Kleiner, A., et al.
(författare)
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Current and pressure gradient triggering and nonlinear saturation of low-n edge harmonic oscillations in tokamaks
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP PUBLISHING LTD. - 0741-3335 .- 1361-6587. ; 61:8
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Tidskriftsartikel (refereegranskat)abstract
- Non-axisymmetric free-boundary equilibrium computations are shown to represent nonlinearly saturated external kink modes and external kink-like sidebands coupled to pressure-driven infernal modes. In this study of edge harmonic oscillations associated with QH-mode plasmas, two different driving mechanisms for external kink type-modes are identified. It is found that standard current-driven external kinks are linearly unstable, and nonlinearly stable in a wide parameter range, especially where q(edge) less than or similar to m/n. But, where standard current-driven kinks are linearly stable coupling of pressure-driven infernal modes can cause instability, and their upper sideband drives edge corrugations that appear to have external kink features. Both types of modes are identified with the VMEC equilibrium code, and the spectra are compared favourably with those of linear numerical approaches and analytic methods. Pressure-driven external infernal modes are shown to robustly occur in sophisticated modelling where the separatrix effect on the q profile is accounted for.
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| 24. |
- Kleiner, A., et al.
(författare)
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Free boundary 3D ideal MHD equilibrium calculations for non-linearly saturated current driven external kink modes in tokamaks
- 2018
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Ingår i: Nuclear Fusion. - : IOP Publishing. - 0029-5515 .- 1741-4326. ; 58:7
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Tidskriftsartikel (refereegranskat)abstract
- It is shown that free boundary 3D equilibrium calculations in tokamak geometry are capable of capturing the physics of non-linearly saturated external kink modes for monotonic current and q profiles typical of standard (baseline) plasma scenarios. The VMEC ideal MHD equilibrium model exhibits strong flux surface corrugations of the plasma vacuum boundary, driven by the core current profile. A method is presented which conveniently extracts the amplitude of the corrugation in terms of Fourier components in straight field line coordinates. The Fourier spectrum, and condition for non-linear corrugation agrees well with linear simulations, and the saturated amplitude agrees well with non-linear analytic calculations.
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| 25. |
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| 26. |
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| 27. |
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| 28. |
- Strandberg, Christer, et al.
(författare)
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All call centres are not " electronic sweatshops" ! : On leadership and psychosocial work conditions in Swedish in-house call centres
- 2007
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Ingår i: The Journal of E-working. - 1872-3284. ; 1:2, s. 116-136
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Tidskriftsartikel (refereegranskat)abstract
- Call centres have received increased attention during the past decades. The growth of this sector in the economy has led to research on its work conditions. Call centres are often described as �sweatshops� with inferior psychosocial work conditions in this research. There are different kinds of call centres, however. This study focuses on the psychosocial work conditions in Swedish in-house call centres compared with the same conditions in Nordic (Swedish, Norwegian, Danish and Finnish) organisations in general. The QPS Nordic questionnaire is used for the comparison. It is found that Swedish in-house call centre employees perceive work to be more controlled than employees in Nordic organisations in general do. At the same time the work load in in-house call centres is not perceived to be very high. The call centre leadership style appears to be different from leadership in general in Nordic organisations. Superiors are perceived to be quite supportive, people-oriented and empowering. Co-workers are also perceived to be supportive. In addition, work is not perceived to be as central in life by call centre employees as it is perceived by employees in Nordic organisations in general.
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| 29. |
- Strandberg, Christer, et al.
(författare)
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Are all centres 'electronic sweatshops'? On leadership and psychological work conditions in in-house call centres.
- 2007
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Ingår i: Proceedings of the 12th International Workshop on Telework.
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Call centres have received increased attention during the past decades. Both because the call centre sector is a fast growing sector in the economy and because of the work conditions offered: call centres are described as �sweatshops�, with inferior psychosocial work conditions. There are different kinds of call centres. In this study the psychosocial work conditions in in-house call centres are compared with the same conditions in Nordic organisations in general. The QPS Nordic questionnaire is used for the comparison. It is found that the in-house call centre employees perceive work to be more controlled than employees in Nordic organisations in general do, but the work load is perceived to be very high. The call centre leadership style appears to be different from leadership in general in Nordic organisations. Superiors are perceived to be quite supportive, people-oriented and empowering. The fellow workers are also perceived to be supportive. In addition to this, work is not perceived to be as central in life by call centre employees as by employees in Nordic organisations in general.
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| 30. |
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| 31. |
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| 32. |
- Strandberg, Christer, et al.
(författare)
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Challenges in serving the mass affluent segment : bank customer perceptions of service quality
- 2012
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Ingår i: Managing Service Quality. - : Emerald. - 0960-4529 .- 1758-8030. ; 22:4, s. 359-385
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Tidskriftsartikel (refereegranskat)abstract
- Purpose - The purpose of this paper is to explore the possible usefulness of a combined multi-attribute and Kano model in analysing how service quality is perceived by mass affluent bank customers. More precisely, to identify quality dimensions, attributes, and items in terms of taken-for-granteds, proportionals, delighters, and neutrals. Design/methodology/approach - Using a survey, the authors measured how mass affluent customers in one region in a major Swedish bank perceived service quality. Responses were analysed with reference to both multi-attribute service quality and Kano models. Findings - The combined model seems to provide some guidance regarding how service quality is perceived by bank customers in the mass affluent segment. The significant number of neutral items reveals potentially wasted resources. The finding of only one delighter item reveals that mass affluent customers are difficult to please. However, substantial heterogeneity exists in customer perceptions of the service quality items investigated. Research limitations/implications - This exploratory study examines only one bank in one region in one country, implying a need for additional research applying this combined model and other methods to investigate private banking in the mass affluent segment. Practical implications - The significant number of neutrals implies that banks might be more efficient if they avoided spending resources on such items. The conspicuous spread in conceptions of service quality items suggests that bank managers and personal bankers may benefit from co-creating services with mass affluent customers. Social implications - Banks are intermediates on financial markets. Improved and customized service quality could make mass affluent customers inclined to invest their resources in ways that promote economic growth. Originality/value - In addition to traditional measurement models, the Kano model may contribute to service quality assessment in private banking.
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| 33. |
- Strandberg, Christer, et al.
(författare)
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Effects of commitment on intentional loyalty at the person-to-person and person-to-firm levels
- 2015
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Ingår i: Journal of Financial Services Marketing. - : Springer Science and Business Media LLC. - 1363-0539 .- 1479-1846. ; 20:3, s. 191-207
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Tidskriftsartikel (refereegranskat)abstract
- This study explores how customers' affective commitment and calculative commitment to the personal adviser and bank, respectively, affect their intentional loyalty to the personal adviser and bank. Data were collected using a web survey of mass affluent customers of a major Swedish bank. Responses were measured and analysed using factor, correlation, and regression analyses. The results reveal that the person-to-person and person-to-firm loyalty categories are influenced by affective and calculative commitment to the personal advisor and by affective commitment to the bank, but not by calculative commitment to the bank. Moreover, there is a strong relationship between customer loyalty to the personal adviser and to the bank. It can be concluded that affective commitment has a stronger overall impact on customer loyalty than does calculative commitment, indicating the importance of creating affective ties with customers, and that personal advisers are central to bank-customer relationships. The importance of financial issues to mass affluent customers implies that both affective commitment and calculative commitment to the personal adviser are important in building customer loyalty to a bank or brand. © 2015 Macmillan Publishers Ltd.
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| 34. |
- Tarras-Wahlberg, Nils, 1973, et al.
(författare)
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Magnetization and Mossbauer study of partially oxidized iron cluster films deposited on HOPG
- 2014
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 367, s. 40-46
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Tidskriftsartikel (refereegranskat)abstract
- Iron clusters produced in a laser vaporization source were deposited to form cluster assembled thin films with different thicknesses on highly oriented pyrolytic graphite substrates. The development of oxidation of the clusters with time, up to three years, was investigated by magnetic measurements using an alternating gradient magnetometer. Furthermore, to receive information about the oxidation states, clusters of 57Fe were studied using Mossbauer spectroscopy. The magnetic analysis shows a time evolution of the saturation magnetization, remanence, and coercivity, determined from the hysteresis curves characteristic of a progressing oxidation. The different thicknesses of the iron cluster films as well as a protective layer of vanadium influence the magnetic properties when the samples are subjected to oxidation with Lime. While the saturation magnetization and remanence decrease and reach half the initial values for almost all the samples after three years, the coercivity increases for all samples and is more substantial for the thickest sample with a vanadium protective layer. This value is three folded after three years. Furthermore, based on a core-shell model and using the saturation magnetization values we have been able to quantitatively calculate the amount of the increase of Fe-oxide as a function of time. The Mossbauer spectroscopy shows peaks corresponding to iron metal and maghemite.
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| 35. |
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| 36. |
- Wahlberg, Christer, et al.
(författare)
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Analysis of global hydromagnetic instabilities driven by strongly sheared toroidal flows in tokamak plasmas
- 2013
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 55:10, s. 105004-
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Tidskriftsartikel (refereegranskat)abstract
- Recent numerical calculations have shown that while strong toroidal rotation can increase the external kink limit of tokamak plasmas, the associated rotation shear can drive a Kelvin-Helmholtz like global instability in the plasma, if the rotation frequency exceeds a threshold value (Chapman et al 2011 Plasma Phys. Control. Fusion 53 125002; Chapman et al 2012 Nucl. Fusion 52 042005). On the basis of a large aspect ratio toroidal expansion of the magnetohydrodynamic stability equations, the present paper investigates analytically various properties of this instability in tokamak plasmas with sonic toroidal flows and low magnetic shear in the core region. We also compare the analytical results with numerical code calculations. Many characteristic features and parameter dependences of the instability can be understood from the analytical theory, such as an eigenmode structure peaking at the position of largest rotation shear, and insensitivity of the growth rate to the plasma beta and to the precise value of the safety factor in the region of low magnetic shear. From an algebraic expression for the growth rate, valid asymptotically at large rotation frequencies, the drop in the dynamic pressure associated with the flow in the plasma can be identified as a major driving mechanism of the instability. For modes with (dominant) poloidal mode number m > 1, and rotating equilibria with isothermal magnetic surfaces, another driving mechanism of the instability is related to the centrifugally induced density variation along the magnetic field lines.
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| 37. |
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| 38. |
- Wahlberg, Christer
(författare)
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Aspect ratio dependence of the ideal internal kink mode stability in a toroidal plasma with circular cross section
- 2004
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Ingår i: Physics of Plasmas. ; 11:5, s. 2119-2134
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Tidskriftsartikel (refereegranskat)abstract
- The theory by Bussac et al. [Phys. Rev. Lett. 35, 1638 (1975)] on the stability of the ideal, internal kink mode in a toroidal plasma with circular cross section is extended to finite values of the inverse aspect ratio ea. The aspect ratio dependence comes from the term following the Bussac term in a large aspect ratio expansion of the potential energy dW of the mode. Although formally of higher order in the inverse aspect ratio, this term is of the same order of magnitude as the Bussac term when the safety factor q is close to (but below) unity at the plasma center and ea is finite. The new term is always stabilizing, but affects dW only marginally when the poloidal beta value beta-p is small and/or ea is small. For values of ea relevant for most tokamaks and beta-p larger than 0.3-0.5, however, the new term strongly modifies dW and leads to a second stability regime of the ideal, internal kink mode, in agreement with earlier numerical calculations.
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| 39. |
- Wahlberg, Christer
(författare)
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Effect of a noncircular plasma cross section on the ideal (1, 1) mode in low-shear tokamaks
- 2007
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 14:4, s. 042506-
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Tidskriftsartikel (refereegranskat)abstract
- The effect of a noncircular shape of the plasma cross section on the ideal magnetohydrodynamic (MHD) stability of the (m,n) = (1,1) internal kink, or quasi-interchange (QI), mode in toroidal plasmas, where the safety factor q is close to unity in a wide area in the plasma core, is analyzed. The analysis is based on previously derived perturbation expansions of the ideal MHD equations for the (1, 1) mode, in the inverse aspect ratio, and in the ellipticity and the triangularity of the plasma cross section. For equilibria having a parabolic pressure profile and a constant central q= q0, with 0< q0 -11, a simple analytical formulation of the stability problem is obtained, and an expression for the eigenfunction in terms of a Bessel function is found. Furthermore, noncircularity of the cross section is found to induce a whole spectrum of (1, 1) ideal modes with eigenvalues approaching the continuum (ω ωA) 2 = (q0 -1)2 3 as the number of nodes in the radial direction goes to infinity. The QI mode is the most unstable mode in this class. If the pressure is low and/or the radius of the low-shear region is small, noncircularity has a small and, usually, destabilizing effect on the QI mode, whereas in plasmas with high pressure and a large radius of the low-shear region, the combined effects of vertical elongation and positive triangularity lead to a substantial improvement of the stability of this mode compared with the situation in plasmas with circular cross section.
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| 40. |
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| 41. |
- Wahlberg, Christer, et al.
(författare)
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Importance of centrifugal effects for the internal kink mode stability in toroidally rotating tokamak plasmas
- 2009
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 16:11, s. 112512-
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Tidskriftsartikel (refereegranskat)abstract
- Analytical theory and two different magnetohydrodynamical stability codes are used in a study of the effects of toroidal plasma rotation on the stability of the ideal, internal kink mode in tokamaks. The focus of the paper is on the role that the centrifugal effects on the plasma equilibrium play for the stability of this mode, and results from one code where centrifugal effects are self-consistently included (CASTOR-FLOW) [E. Strumberger et al, Nucl. Fusion 45, 1156 (2005)] are compared with the results from another code where such effects are not taken into account (MISHKA-F) [I. T. Chapman et al., Phys. Plasmas 13, 062511 (2006)]. It is found that, even at rather modest flow speeds, the centrifugal effects are very important for the stability of the internal kink mode. While the results from the two codes can be quite similar for certain profiles in the plasma, completely opposite results are obtained for other profiles. A very good agreement between analytical theory and the numerical results are, both for inconsistent and consistent equilibria, found for plasmas with large aspect ratio. From the analytical theory, the distinctly different stability properties of equilibria with and without centrifugal effects included can be traced to the stabilizing effect of the geodesic acoustic mode (GAM) induced by the plasma rotation. This GAM exists solely as a consequence of the nonuniform plasma density and pressure created by the centrifugal force on the flux surfaces, and a stabilizing coupling of the internal kink instability to this mode cannot therefore take place if the centrifugal effects are not included in the equilibrium. In addition to the GAM stabilization. the effects of the radial profiles of the plasma density and rotation velocity are also found to be significant, and the importance of these effects increases with decreasing aspect ratio.
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| 42. |
- Wahlberg, Christer, et al.
(författare)
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Magnetohydrodynamic theory of the global structure and magnetic components of the geodesic acoustic continuum modes in tokamaks
- 2016
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 58:7
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Tidskriftsartikel (refereegranskat)abstract
- Ideal magnetohydrodynamic (MHD) theory is used to investigate some of the fundamental properties of the geodesic acoustic continuum modes (GAMs) in tokamaks, including their global structure, their associated magnetic components both inside and outside the plasma, and effects of a non-circular cross section of the plasma. In addition to the well-known m = 1 side-bands in the perturbed density and pressure of the (electrostatic) GAM, the MHD continuum GAM also includes a m = 1 side-band in the perturbed toroidal magnetic field as well as m = 2 side-bands in the perturbed density, pressure, poloidal flow and in the magnetic components delta B-r and delta B-theta (m is the poloidal mode number). These m = 2 side-bands exist within the whole plasma and the magnetic components also outside the plasma, and the magnitudes of these components in the vacuum region are calculated in the paper. It is shown that, for plasmas with a conducting wall not too far from the plasma surface, the perturbed magnetic field in the vacuum region is dominated by its poloidal component delta B-theta, with poloidal dependence sin 2 theta, in agreement with experiments. Aspects of the plasma equilibrium that affect the magnitude of the perturbed magnetic field in the vacuum region are discussed in the paper. Furthermore, the influence of a non-circular plasma cross section on the GAM frequency and on the spectrum of the global, perturbed magnetic field is analysed. It is found that the only significant effect of a non-circular cross section on the GAM frequency comes from elongation and its variation across the plasma radius. However, higher-order shaping effects, as well as finite aspect ratio, induce other Fourier components than m = 2 in the magnetic halo that surrounds the GAM surface.
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| 43. |
- Wahlberg, Christer, et al.
(författare)
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Pressure- and q-profile effects on ideal infernal modes in tokamaks with an extended region of low magnetic shear
- 2011
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Ingår i: 38th EPS Conference on Plasma Physics 2011 (EPS 2011). - 9781618395931 ; , s. 1664-1667
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Konferensbidrag (refereegranskat)abstract
- An extended region of low magnetic shear is a common feature of the plasma in many tokamak experiments. Such a region can involve a substantial part of the entire plasma volume, for instance in "hybrid scenario" plasmas characterized by a nearly constant safety factor q 1 in the plasma core, and also in equilibria with similar profiles of q that are often developing in spherical tokamaks. Regions around rational surfaces where q is locally flattened could occur in the presence of an island, or as a result of partial reconnection. Such a flattening of q deteriorates the ideal stability of the plasma due to the reduced stabilising effect of field-line bending. A class of global instabilities that can grow in such regions are the "infernal" modes first discussed by Manickam et al. [1]. In the present work we study both q- profile and pressure profile effects on these kind of modes using an analytical formulation of the ideal MHD stability equations for a toroidal plasma with large aspect ratio (LAR). In the next section we present a system of equations useful for analyzing the ideal stability of LAR tokamaks including a region of low magnetic shear between an inner radius rIN and an outer radius r0uT (and finite magnetic shear outside this region). This system is thereafter used to investigate combined q- and pressure profile effects on the infernal modes in low-shear equilibria with q 1 in the core region, in particular the m = n > 1 modes. We consider first a family of profiles of similar nature as those used in Ref. [1], and thereafter look at the stability of a somewhat similar plasma, having low shear in the vicinity of the q = 1 rational surface and q0 < 1 at the magnetic axis. It will be shown that, under certain circumstances, a broad spectrum of infernal n > 1 instabilities can exist in such equilibria, and a possible connection between such modes and the sawtooth instability is pointed out.
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| 44. |
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| 45. |
- Wahlberg, Christer, et al.
(författare)
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Singular global components and frequency shift of the geodesic acoustic continuum modes in shaped tokamaks
- 2019
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Ingår i: Plasma Physics and Controlled Fusion. - : IOP PUBLISHING LTD. - 0741-3335 .- 1361-6587. ; 61:7
-
Tidskriftsartikel (refereegranskat)abstract
- Within the ideal magnetohydrodynamic (MHD) model, the geodesic acoustic modes (GAMs) in tokamaks derived by Winsor et al (1968 Phys. Fluids 11 2448) belong to the continuous spectrum, characterised by unbounded non-square integrable eigenfunctions (delta functions) at the singular surfaces (Goedbloed 1975 Phys. Fluids 18 1258). The eigenfunctions of the MHD continua in cylindrical as well as toroidal plasmas include, in addition, components that exist outside the singular surfaces and have singularities of type (psi - psi(0))(-1) or ln, vertical bar psi - psi(0)vertical bar where psi is a flux function that labels the magnetic surfaces, and psi = psi(0) defines the singular surface (Pao 1975 Nucl. Fusion 15 631). Using a large aspect ratio approximation of tokamak plasmas it is shown in this paper that the GAMs indeed include such singular components. Hence, in addition to the non-square integrable m = 0 and m = 1 components of the plasma flow and of the density and pressure perturbations at the GAM surface, the GAM continua also include accompanying m = 0 and m = 1 singular components varying as (psi - psi(0))(-1) This gives the m = 0 and m = 1 components of each GAM in the continuum radially extended profiles and a global character also within ideal theory. To the same order in the expansion, effects of a finite aspect ratio and a non-circular plasma cross section on the GAM frequency are also calculated, and we recover the dependence on inverse aspect ratio and Shafranov shift of the real GAM frequency previously calculated within gyrokinetic theory by Gao (2010 Phys. Plasmas 17 092503). Furthermore, while the dominating shaping effect on the GAM frequency comes from plasma elongation, as shown previously, it is shown in this paper that there is a higher-order triangularity effect that can also be significant. The calculated triangularity effect predicts a nearly linearly increasing GAM frequency with increasing triangularity, a phenomenon observed also in the TCV tokamak.
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| 46. |
- Wahlberg, Christer, et al.
(författare)
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Stability analysis of internal ideal modes in low-shear tokamaks
- 2007
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Ingår i: Physics of Plasmas. - : AIP Publishing. - 1070-664X .- 1089-7674. ; 14:11, s. 110703-
-
Tidskriftsartikel (refereegranskat)abstract
- The stability of internal, ideal modes in tokamaks with low magnetic shear in the plasma core is analyzed. For equilibria with large aspect ratio, a parabolic pressure profile and a flat q profile in the core, an exact solution of the ideal magnetohydrodynamic (MHD) stability equations is found. The solution includes the eigenfunctions and the complete spectra of two distinctly different MHD phenomena: A family of fast-growing, Mercier-unstable global eigenmodes localized in a low-shear region with q < 1, and another, related family of stable, global eigenmodes existing in plasmas with q > 1 in the core. In the latter case the solution in addition includes one unstable eigenmode, if beta is larger than a critical value depending on the width of the low-shear region and on the q-profile in the edge region.
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| 47. |
- Wahlberg, Christer
(författare)
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Stability analysis of the ideal internal kink mode in a toroidally rotating tokamak plasma with ultra flat q profile
- 2004
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Ingår i: 12th International Congress on Plasma Physics, October 25 - 29 2004, Nice, France. ; , s. P1-090
-
Konferensbidrag (refereegranskat)abstract
- The ideal MHD stability of the m = n = 1 internal kink, or “quasi-interchange” mode in a toroidally rotating tokamak plasma with the safety factor q ≈ 1 within a wide area in the plasma core is analysed. It is shown that rigid, toroidal rotation stabilizes this mode if the rotation frequency (Omega) is larger than a critical frequency Omega-crit. Unless the plasma pressure and the radial extent of the region with ultra flat q both are rather large, rotation frequencies of the order of a few percent of the Alfvén frequency are found to be sufficient to stabilize the quasi-interchange mode. The stabilization is caused by the nonuniform plasma density and associated Brunt-Väisälä frequency created by the centrifugal force. When Omega exceeds Omega-crit, the quasi-interchange instability transforms into a stable oscillation with a frequency close to the lowest Brunt-Väisälä frequency in the region with ultra flat q. This stabilizing mechanism may be of interest for the interpretation of tokamak discharges in the “hybrid scenario”, and in discharges in the spherical tokamak NSTX where stabilization of the internal kink mode by toroidal rotation has been observed.
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| 48. |
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| 49. |
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| 50. |
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