1. |
- Bengtsson, Caroline, et al.
(author)
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Chronic rhinosinusitis impairs sleep quality : results of the GA(2)LEN study
- 2017
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In: Sleep. - : Oxford University Press. - 0161-8105 .- 1550-9109. ; 40:1
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Journal article (peer-reviewed)abstract
- STUDY OBJECTIVES: To analyse the prevalence of sleep problems in subjects with CRS and to determine whether the disease severity of CRS affects sleep quality.METHODS: Questionnaires were sent to a random sample of 45 000 adults in four Swedish cities. Questions on CRS, asthma, allergic rhinitis, co-morbidities, tobacco use, educational level and physical activity were included. CRS was defined according to the European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS) epidemiological criteria. The disease severity of CRS was defined by the number of reported CRS symptoms. Sleep quality was assessed using the Basic Nordic Sleep Questionnaire.RESULTS: Of the 26 647 subjects, 2249 (8.4%) had CRS. Reported sleep problems were 50-90% more common among subjects with CRS compared with those without or the total population. The prevalence of reported sleep problems increased in conjunction with the severity of CRS. After adjusting for gender, BMI, age, tobacco use, asthma, somatic diseases, physical activity level and educational level, participants with four symptoms of CRS (compared with subjects without CRS symptoms) displayed a higher risk of snoring (adj. OR (95% CI): 3.13 (2.22-4.41)), difficulties inducing sleep (3.98 (2.94-5.40)), difficulties maintaining sleep (3.44 (2.55-4.64)), early morning awakening (4.71 (3.47-6.38)) and excessive daytime sleepiness (4.56 (3.36-6.18)). The addition of persistent allergic rhinitis to CRS further increased the risk of sleep problems.CONCLUSIONS: Sleep problems are highly prevalent among subjects with CRS. The disease severity of CRS negatively affects sleep quality.
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2. |
- Brodin, Gert, 1963-, et al.
(author)
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Interaction between gravitational waves and plasma waves in the Vlasov description
- 2010
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In: Journal of Plasma Physics. - : Cambridge University Press. - 0022-3778 .- 1469-7807. ; :76, s. 345-353
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Journal article (peer-reviewed)abstract
- The nonlinear interaction between electromagnetic, electrostatic and gravitational waves in a Vlasov plasma is reconsidered. By using a orthonormal tetrad description the three-wave coupling coefficients are computed. Comparing with previous results, it is found that the present theory leads to algebraic expression that are much reduced, as compared to those computed using a coordinate frame formalism. Furthermore, here we calculate the back reaction on the gravitational waves, and a simple energy conservation law is deduced in the limit of a cold plasma.
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3. |
- Forsberg, Mats, 1978-
(author)
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Gravitational perturbations in plasmas and cosmology
- 2010
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Doctoral thesis (other academic/artistic)abstract
- Gravitational perturbations can be in the form of scalars, vectors or tensors. This thesis focuses on the evolution of scalar perturbations in cosmology, and interactions between tensor perturbations, in the form of gravitational waves, and plasma waves. The gravitational waves studied in this thesis are assumed to have small amplitudes and wavelengths much shorter than the background length scale, allowing for the assumption of a flat background metric. Interactions between gravitational waves and plasmas are described by the Einstein-Maxwell-Vlasov, or the Einstein-Maxwell-fluid equations, depending on the level of detail required. Using such models, linear wave excitation of various waves by gravitational waves in astrophysical plasmas are studied, with a focus on resonance effects. Furthermore, the influence of strong magnetic field quantum electrodynamics, leading to detuning of the gravitational wave-electromagnetic wave resonances, is considered. Various nonlinear phenomena, including parametric excitation and wave steepening are also studied in different astrophysical settings. In cosmology the evolution of gravitational perturbations are of interest in processes such as structure formation and generation of large scale magnetic fields. Here, the growth of density perturbations in Kantowski-Sachs cosmologies with positive cosmological constant is studied.
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4. |
- Forsberg, Mats, 1978-, et al.
(author)
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Harmonic generation of gravitational wave induced Alfven waves
- 2008
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In: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 77:2, s. 024050-024050-6
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Journal article (peer-reviewed)abstract
- Here we consider the nonlinear evolution of Alfvén waves that have been excited by gravitational waves from merging binary pulsars. We derive a wave equation for strongly nonlinear and dispersive Alfvén waves. Because of the weak dispersion of the Alfvén waves, significant wave steepening can occur, which in turn implies strong harmonic generation. We find that the harmonic generation is saturated due to dispersive effects, and use this to estimate the resulting spectrum. Finally we discuss the possibility of observing the above process.
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5. |
- Forsberg, Mats, 1978-, et al.
(author)
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Influence of strong field vacuum polarization on gravitational-electromagnetic wave interaction
- 2010
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In: Physical Review D. Particles and fields. - 0556-2821 .- 1089-4918. ; 82:2, s. 024001-024001-7
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Journal article (peer-reviewed)abstract
- The interaction between gravitational and electromagnetic waves in the presence of a static magnetic field is studied. The field strength of the static field is allowed to surpass the Schwinger critical field, such that the QED effects of vacuum polarization and magnetization are significant. Equations governing the interaction are derived and analyzed. It turns out that the energy conversion from gravitational to electromagnetic waves can be significantly altered due to the QED effects. The consequences of our results are discussed.
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6. |
- Forsberg, Mats, 1978-, et al.
(author)
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Nonlinear interactions between gravitational radiation and modified Alfvén modes in astrophysical dusty plasmas
- 2006
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In: Physical Review D. Particles and fields. - : American Physical Society. - 0556-2821 .- 1089-4918. ; 74, s. 064014-064014-5
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Journal article (peer-reviewed)abstract
- We present an investigation of nonlinear interactions between gravitational radiation and modified Alfvén modes in astrophysical dusty plasmas. Assuming that stationary charged dust grains form neutralizing background in an electron-ion-dust plasma, we obtain the three-wave coupling coefficients and calculate the growth rates for parametrically coupled gravitational radiation and modified Alfvén-Rao modes. The threshold value of the gravitational wave amplitude associated with convective stabilization is particularly small if the gravitational frequency is close to twice the modified Alfvén wave frequency. The implication of our results to astrophysical dusty plasmas is discussed.
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