| 1. |
- Bengtsson, Per Erik, et al.
(författare)
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Dual-broadband rotational cars measurements in an IC engine
- 1994
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Ingår i: Symposium (International) on Combustion. - 0082-0784. ; 25:1, s. 1735-1742
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Tidskriftsartikel (refereegranskat)abstract
- This is the first report of pure rotational coherent anti-Stokes Raman spectroscopy (CARS) measurementsin an internal combustion (IC) engine. Single-shot, dual-broadband rotational CARS (DB-RCARS) spectra were recorded both prior to ignition and in the postcombustion gases. From these spectra, both temperature and relative oxygen concentrations were evaluated. The pressure was registered simultaneously with the CARS measurements in the spark-ignition engine burning natural gas and air. Prior to ignition, normally at temperatures below 1000 K and pressures below 2 MPa, a rotational CARS spectrum is very temperature sensitive, and the technique can be used for temperature measurements with high accuracy. Evaluated temperatures show a negligible dependence on uncertainties in parameters such as the nonresonant susceptibility of the gas and the slit width. Moreover, no collisional narrowing of the lines has to be taken into account. The relative standard deviation of evaluated temperatures and of relative oxygen concentrations from single-shot measurements were as low as 1, and 1.4-1.9%, respectively. In the postcombustion gases at temperatures above 2000 K and pressures above 1.5 MPa, the nonresonant CARS background gave a large contribution to the total spectrum. In this temperature and pressure range, the evaluated values of temperature and nonresonant susceptibility are not independent, and the nonresonant susceptibility had to be fixed at a precalculated value to get a reliable temperature evaluation. The avantages and disadvantages of rotational CARS in comparison with vibrational CARS for IC engine measurements are discussed.
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| 2. |
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| 3. |
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| 4. |
- Akselsson, Roland, et al.
(författare)
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Aerosoler
- 1994
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Bok (övrigt vetenskapligt/konstnärligt)
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| 5. |
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| 6. |
- Andell, Pontus, et al.
(författare)
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Epidemiology of valvular heart disease in a Swedish nationwide hospital-based register study
- 2017
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Ingår i: Heart. - : BMJ. - 1355-6037 .- 1468-201X. ; 103:21, s. 1696-1703
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Tidskriftsartikel (refereegranskat)abstract
- Objective: Transitions in the spectrum of valvular heart diseases (VHDs) in developed countries over the 20th century have been reported from clinical case series, but large, contemporary population-based studies are lacking.Methods: We used nationwide registers to identify all patients with a first diagnosis of VHD at Swedish hospitals between 2003 and 2010. Age-stratified and sex-stratified incidence of each VHD and adjusted comorbidity profiles were assessed.Results: In the Swedish population (n=10 164 211), the incidence of VHD was 63.9 per 100 000 person-years, with aortic stenosis (AS; 47.2%), mitral regurgitation (MR; 24.2%) and aortic regurgitation (AR; 18.0%) contributing most of the VHD diagnoses. The majority of VHDs were diagnosed in the elderly (68.9% in subjects aged ≥65 years), but pulmonary valve disease incidence peaked in newborns. Incidences of AR, AS and MR were higher in men who were also more frequently diagnosed at an earlier age. Mitral stenosis (MS) incidence was higher in women. Rheumatic fever was rare. Half of AS cases had concomitant atherosclerotic vascular disease (48.4%), whereas concomitant heart failure and atrial fibrillation were common in mitral valve disease and tricuspid regurgitation. Other common comorbidities were thoracic aortic aneurysms in AR (10.3%), autoimmune disorders in MS (24.5%) and abdominal hernias or prolapse in MR (10.7%) and TR (10.3%).Conclusions: Clinically diagnosed VHD was primarily a disease of the elderly. Rheumatic fever was rare in Sweden, but specific VHDs showed a range of different comorbidity profiles . Pronounced sex-specific patterns were observed for AR and MS, for which the mechanisms remain incompletely understood.
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| 7. |
- Andell, Pontus, et al.
(författare)
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Neighborhood socioeconomic status and aortic stenosis : A Swedish study based on nationwide registries and an echocardiographic screening cohort
- 2020
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Ingår i: International Journal of Cardiology. - : Elsevier BV. - 0167-5273 .- 1874-1754. ; 318, s. 153-159
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Tidskriftsartikel (refereegranskat)abstract
- Background: Aortic stenosis (AS) is the most common valvular heart disease in developed countries, confers high mortality in advanced cases, but can effectively be reversed using endovascular or open-heart surgery. We evaluated the association between AS and neighborhood socioeconomic status (NSES). Methods: We used Swedish population-based nationwide registers and an echocardiography screening cohort during the study period 1997–2014. NSES was determined by an established neighborhood deprivation index composed of education, income, unemployment, and receipt of social welfare. Multilevel adjusted logistic regression models determined the association between NSES and incident AS (according to ICD-10 diagnostic codes). Results: The study population of men and women (n=6,641,905) was divided into individuals living in high (n = 1,608,815 [24%]), moderate (n = 3,857,367 [58%]) and low (n = 1,175,723 [18%]) SES neighborhoods. There were 63,227 AS cases in total. Low NSES (versus high) was associated with a slightly increased risk of AS (OR 1.06 [95% CI 1.03–1.08]) in the nationwide study population. In the echocardiography screening cohort (n = 1586), the association between low NSES and AS was markedly stronger (OR: 2.73 [1.05–7.12]). There were more previously undiagnosed AS cases in low compared to high SES neighborhoods (3.1% versus 1.0%). Conclusions: In this nationwide Swedish register study, low NSES was associated with a slightly increased risk of incident AS. However, the association was markedly stronger in the echocardiography screening cohort, which revealed an almost three-fold increase of AS among individuals living in low SES neighborhoods, possibly indicating an underdiagnosis of AS among these individuals.
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| 8. |
- Andersson, Sandra, et al.
(författare)
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Composition and evolution of volcanic aerosol from eruptions of Kasatochi, Sarychev and Eyjafjallajokull in 2008-2010 based on CARIBIC observations
- 2013
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Ingår i: Atmospheric Chemistry and Physics. - : Copernicus GmbH. - 1680-7324. ; 13:4, s. 1781-1796
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Tidskriftsartikel (refereegranskat)abstract
- Large volcanic eruptions impact significantly on climate and lead to ozone depletion due to injection of particles and gases into the stratosphere where their residence times are long. In this the composition of volcanic aerosol is an important but inadequately studied factor. Samples of volcanically influenced aerosol were collected following the Kasatochi (Alaska), Sarychev (Russia) and also during the Eyjafjallajokull (Iceland) eruptions in the period 2008-2010. Sampling was conducted by the CARIBIC platform during regular flights at an altitude of 10-12 km as well as during dedicated flights through the volcanic clouds from the eruption of Eyjafjallajokull in spring 2010. Elemental concentrations of the collected aerosol were obtained by accelerator-based analysis. Aerosol from the Eyjafjallajokull volcanic clouds was identified by high concentrations of sulphur and elements pointing to crustal origin, and confirmed by trajectory analysis. Signatures of volcanic influence were also used to detect volcanic aerosol in stratospheric samples collected following the Sarychev and Kasatochi eruptions. In total it was possible to identify 17 relevant samples collected between 1 and more than 100 days following the eruptions studied. The volcanically influenced aerosol mainly consisted of ash, sulphate and included a carbonaceous component. Samples collected in the volcanic cloud from Eyjafjallajokull were dominated by the ash and sulphate component (similar to 45% each) while samples collected in the tropopause region and LMS mainly consisted of sulphate (50-77%) and carbon (21-43%). These fractions were increasing/decreasing with the age of the aerosol. Because of the long observation period, it was possible to analyze the evolution of the relationship between the ash and sulphate components of the volcanic aerosol. From this analysis the residence time (1/e) of sulphur dioxide in the studied volcanic cloud was estimated to be 45 +/- 22 days.
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| 9. |
- Andersson, Sandra, et al.
(författare)
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Significant radiative impact of volcanic aerosol in the lowermost stratosphere.
- 2015
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Ingår i: Nature Communications. - : Springer Science and Business Media LLC. - 2041-1723. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- Despite their potential to slow global warming, until recently, the radiative forcing associated with volcanic aerosols in the lowermost stratosphere (LMS) had not been considered. Here we study volcanic aerosol changes in the stratosphere using lidar measurements from the NASA CALIPSO satellite and aircraft measurements from the IAGOS-CARIBIC observatory. Between 2008 and 2012 volcanism frequently affected the Northern Hemisphere stratosphere aerosol loadings, whereas the Southern Hemisphere generally had loadings close to background conditions. We show that half of the global stratospheric aerosol optical depth following the Kasatochi, Sarychev and Nabro eruptions is attributable to LMS aerosol. On average, 30% of the global stratospheric aerosol optical depth originated in the LMS during the period 2008-2011. On the basis of the two independent, high-resolution measurement methods, we show that the LMS makes an important contribution to the overall volcanic forcing.
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| 10. |
- Asking, Lars, et al.
(författare)
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An electrostatic aerosol sampler
- 1988
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Ingår i: Journal of Aerosol Science. - : Elsevier BV. - 0021-8502. ; 19:7, s. 1023-1026
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Tidskriftsartikel (refereegranskat)
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