| 21. |
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| 22. |
- Alho, Markku, et al.
(författare)
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Hybrid modeling of cometary plasma environments : II. Remote-sensing of a cometary bow shock
- 2019
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Ingår i: Astronomy and Astrophysics. - : EDP Sciences. - 0004-6361 .- 1432-0746. ; 630
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Tidskriftsartikel (refereegranskat)abstract
- Context. The ESA Rosetta probe has not seen direct evidence of a fully formed bow shock at comet 67P/Churyumov–Gerasimenko (67P). Ion spectrometer measurements of cometary pickup ions measured in the vicinity of the nucleus of 67P are available and may contain signatures of the large-scale plasma environment.Aims. The aim is to investigate the possibility of using pickup ion signatures to infer the existence or nonexistence of a bow shock-like structure and possibly other large-scale plasma environment features.Methods. A numerical plasma model in the hybrid plasma description was used to model the plasma environment of a comet. Simulated pickup ion spectra were generated for different interplanetary magnetic field conditions. The results were interpreted through test particle tracing in the hybrid simulation solutions.Results. Features of the observed pickup ion energy spectrum were reproduced, and the model was used to interpret the observation to be consistent with a shock-like structure. We identify (1) a spectral break related to the bow shock, (2) a mechanism for generating the spectral break, and (3) a dependency of the energy of the spectral break on the interplanetary magnetic field magnitude and bow shock standoff distance.
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| 23. |
- Amm, O., Janhunen, P., Kauristie, K., Opgenoorth, H.J., Pulkkinen, T.I. and Viljanen, A.
(författare)
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Mesoscale ionospheric electrodynamics observed with the MIRACLE network: 1. Analysis of a pseudobreakup spiral.
- 2001
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Ingår i: Journal of Geophysical Research. ; 106:111, s. 24675-24690
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Tidskriftsartikel (refereegranskat)abstract
- A short-lived auroral spiral is observed on February 3, 1999, around 2204 UT, using the Multi-Instrument Array for Ionosphere-Magnetosphere Coupling Studies (MIRACLE) network of ground-based instruments in Fennoscandia, which consists of magnetometers, co
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| 24. |
- Andreeova, K., et al.
(författare)
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Shock propagation in the magnetosphere : Observations and MHD simulations compared
- 2008
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 113:A9, s. A09224-
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Tidskriftsartikel (refereegranskat)abstract
- We examine the propagation of disturbances in the Earth's magnetosphere caused by fast forward shock interaction with the magnetopause. Our statistical study and event analyses show that the propagation speeds are larger in the magnetosphere than in the solar wind and are larger in the nightside magnetosphere than in the dayside magnetosphere. A case study of a double shock during 9 November 2002 is examined both observationally and using the GUMICS-4 global MHD simulation. Tracing the disturbance propagation allows us to confirm that the MHD simulation results are in good agreement with the in situ observations. The simulation results show that the propagation of the disturbance occurs in the antisunward direction at all clock angles simultaneously. However, changes in the magnetosheath are largest at high latitudes, while in the magnetotail the largest variations are seen in the plasma sheet.
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| 25. |
- Apatenkov, S. V., et al.
(författare)
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Multi-spacecraft observation of plasma dipolarization/injection in the inner magnetosphere
- 2007
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Ingår i: Annales Geophysicae. - 0992-7689 .- 1432-0576. ; 25:3, s. 801-814
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Tidskriftsartikel (refereegranskat)abstract
- Addressing the origin of the energetic particle injections into the inner magnetosphere, we investigate the 23 February 2004 substorm using a favorable constellation of four Cluster (near perigee), LANL and Geotail spacecraft. Both an energy-dispersed and a dispersionless injection were observed by Cluster crossing the plasma sheet horn, which mapped to 9-12 R-E in the equatorial plane close to the midnight meridian. Two associated narrow equatorward auroral tongues/streamers propagating from the oval poleward boundary could be discerned in the global images obtained by IMAGE/WIC. As compared to the energy-dispersed event, the dispersionless injection front has important distinctions consequently repeated at 4 spacecraft: a simultaneous increase in electron fluxes at energies similar to 1.300 keV, similar to 25 nT increase in B-Z and a local increase by a factor 1.5-1.7 in plasma pressure. The injected plasma was primarily of solar wind origin. We evaluated the change in the injected flux tube configuration during the dipolarization by fitting flux increases observed by the PEACE and RAPID instruments, assuming adiabatic heating and the Liouville theorem. Mapping the locations of the injection front detected by the four spacecraft to the equatorial plane, we estimated the injection front thickness to be similar to 1 R-E and the earthward propagation speed to be similar to 200-400km/s (at 9-12 RE). Based on observed injection properties, we suggest that it is the underpopulated flux tubes (bubbles with enhanced magnetic field and sharp inner front propagating earthward), which accelerate and transport particles into the strong-field dipolar region.
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| 26. |
- Bergh, Camilla, et al.
(författare)
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Increased risk of revision in patients with non-traumatic femoral head necrosis.
- 2014
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Ingår i: Acta orthopaedica. - : Medical Journals Sweden AB. - 1745-3682 .- 1745-3674. ; 85:1, s. 11-17
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Tidskriftsartikel (refereegranskat)abstract
- Background and purpose Previous studies of patients who have undergone total hip arthroplasty (THA) due to femoral head necrosis (FHN) have shown an increased risk of revision compared to cases with primary osteoarthritis (POA), but recent studies have suggested that this procedure is not associated with poor outcome. We compared the risk of revision after operation with THA due to FHN or POA in the Nordic Arthroplasty Register Association (NARA) database including Denmark, Finland, Norway, and Sweden. Patients and methods 427,806 THAs performed between 1995 and 2011 were included. The relative risk of revision for any reason, for aseptic loosening, dislocation, deep infection, and periprosthetic fracture was studied before and after adjustment for covariates using Cox regression models. Results 416,217 hips with POA (mean age 69 (SD 10), 59% females) and 11,589 with FHN (mean age 65 (SD 16), 58% females) were registered. The mean follow-up was 6.3 (SD 4.3) years. After 2 years of observation, 1.7% in the POA group and 3.0% in the FHN group had been revised. The corresponding proportions after 16 years of observation were 4.2% and 6.1%, respectively. The 16-year survival in the 2 groups was 86% (95% CI: 86-86) and 77% (CI: 74-80). After adjusting for covariates, the relative risk (RR) of revision for any reason was higher in patients with FHN for both periods studied (up to 2 years: RR = 1.44, 95% CI: 1.34-1.54; p < 0.001; and 2-16 years: RR = 1.25, 1.14-1.38; p < 0.001). Interpretation Patients with FHN had an overall increased risk of revision. This increased risk persisted over the entire period of observation and covered more or less all of the 4 most common reasons for revision.
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| 27. |
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| 28. |
- de Mello, Vanessa D. F., et al.
(författare)
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The effect of fatty or lean fish intake on inflammatory gene expression in peripheral blood mononuclear cells of patients with coronary heart disease
- 2009
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Ingår i: European Journal of Nutrition. - : Steinkopff-Verlag. - 1436-6207 .- 1436-6215. ; 48:8, s. 447-455
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Little is known about the effect of fish consumption on gene expression of inflammation-related genes in immune cells in coronary heart disease (CHD).AIM OF THE STUDY: We sought to evaluate the effect of a fatty fish (FF) or a lean fish (LF) diet on the modulation of inflammatory and endothelial function-related genes in peripheral blood mononuclear cells (PBMCs) of subjects with CHD, and its association with serum fatty acid (FA) profile and lipid metabolic compounds.METHODS: Data from 27 patients randomized into an 8-week FF (n = 10; mean +/- SD: 4.3 +/- 0.4 portions of fish per week), LF (n = 11; 4.7 +/- 1.1 portions of fish per week), or control diet (n = 6; 0.6 +/- 0.4 portions of fish per week) were analyzed. The mRNA expression was measured using real-time PCR.RESULTS: The effect of the intervention on the mRNA expression of the genes studied did not differ among groups. In the FF group, however, the decrease in arachidonic acid to eicosapentaenoic acid (AA:EPA) ratio in cholesterol ester and phospholipid fractions strongly correlated with the change in IL1B mRNA levels (r (s) = 0.60, P = 0.06 and r (s) = 0.86, P = 0.002, respectively). In the LF group, the decrease in palmitic acid and total saturated FAs in cholesterol esters correlated with the change in intercellular cell adhesion molecule-1 (ICAM1) expression (r (s) = 0.64, P = 0.04 for both). Circulating levels of soluble ICAM-1 decreased only in the LF group (P < 0.05).CONCLUSIONS: The intake of FF or LF diet did not alter the expression of inflammatory and endothelial function-related genes in PBMCs of patients with CHD. However, the decrease in AA:EPA ratio in serum lipids in the FF group may induce an anti-inflammatory response at mRNA levels in PBMCs. A LF diet might benefit endothelial function, possibly mediated by the changes in serum FA composition.
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| 29. |
- Dimmock, Andrew P., et al.
(författare)
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Direct evidence of nonstationary collisionless shocks in space plasmas
- 2019
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Ingår i: Science Advances. - : AMER ASSOC ADVANCEMENT SCIENCE. - 2375-2548. ; 5:2
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Tidskriftsartikel (refereegranskat)abstract
- Collisionless shocks are ubiquitous throughout the universe: around stars, supernova remnants, active galactic nuclei, binary systems, comets, and planets. Key information is carried by electromagnetic emissions from particles accelerated by high Mach number collisionless shocks. These shocks are intrinsically nonstationary, and the characteristic physical scales responsible for particle acceleration remain unknown. Quantifying these scales is crucial, as it affects the fundamental process of redistributing upstream plasma kinetic energy into other degrees of freedom-particularly electron thermalization. Direct in situ measurements of nonstationary shock dynamics have not been reported. Thus, the model that best describes this process has remained unknown. Here, we present direct evidence demonstrating that the transition to nonstationarity is associated with electron-scale field structures inside the shock ramp.
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| 30. |
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