| 1. |
- Benavent, N., et al.
(författare)
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Substantial contribution of iodine to Arctic ozone destruction
- 2022
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Ingår i: Nature Geoscience. - : Springer Science and Business Media LLC. - 1752-0894 .- 1752-0908. ; 15, s. 770-773
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Tidskriftsartikel (refereegranskat)abstract
- Unlike bromine, the effect of iodine chemistry on the Arctic surface ozone budget is poorly constrained. We present ship-based measurements of halogen oxides in the high Arctic boundary layer from the sunlit period of March to October 2020 and show that iodine enhances springtime tropospheric ozone depletion. We find that chemical reactions between iodine and ozone are the second highest contributor to ozone loss over the study period, after ozone photolysis-initiated loss and ahead of bromine.
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| 2. |
- Sze, K. C. H., et al.
(författare)
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Ice-nucleating particles in northern Greenland: annual cycles, biological contribution and parameterizations
- 2023
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Ingår i: Atmospheric Chemistry and Physics. - 1680-7316. ; 23:8, s. 4741-4761
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Tidskriftsartikel (refereegranskat)abstract
- Ice-nucleating particles (INPs) can initiate ice formation in clouds at temperatures above - 38 C-? through heterogeneous ice nucleation. As a result, INPs affect cloud microphysical and radiative properties, cloud lifetime, and precipitation behavior and thereby ultimately the Earth's climate. Yet, little is known regarding the sources, abundance and properties of INPs, especially in remote regions such as the Arctic. In this study, 2 -yearlong INP measurements (from July 2018 to September 2020) at Villum Research Station in northern Greenland are presented. A low-volume filter sampler was deployed to collect filter samples for offline INP analysis. An annual cycle of INP concentration (NINP) was observed, and the fraction of heat-labile INPs was found to be higher in months with low to no snow cover and lower in months when the surface was well covered in snow (> 0.8 m). Samples were categorized into three different types based only on the slope of their INP spectra, namely into summer, winter and mix type. For each of the types a temperature-dependent INP parameterization was derived, clearly different depending on the time of the year. Winter and summer types occurred only during their respective seasons and were seen 60 % of the time. The mixed type occurred in the remaining 40 % of the time throughout the year. April, May and November were found to be transition months. A case study comparing April 2019 and April 2020 was performed. The month of April was selected because a significant difference in NINP was observed during these two periods, with clearly higher NINP in April 2020. In parallel to the observed differences in NINP, also a higher cloud-ice fraction was observed in satellite data for April 2020, compared to April 2019. NINP in the case study period revealed no clear dependency on either meteorological parameters or different surface types which were passed by the collected air masses. Overall, the results suggest that the coastal regions of Greenland were the main sources of INPs in April 2019 and 2020, most likely including both local terrestrial and marine sources.
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| 3. |
- Nøjgaard, J. K., et al.
(författare)
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A local marine source of atmospheric particles in the High Arctic
- 2022
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Ingår i: Atmospheric Environment. - : Elsevier BV. - 1352-2310. ; 285
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Tidskriftsartikel (refereegranskat)abstract
- The chemical composition of non-refractory submicron aerosol (NR-PM1) was characterized at the Villum Research Station (Villum) at Station Nord in North Greenland during spring-summer 2016 using a Time of Flight Aerosol Chemical Speciation Monitor (ToF-ACSM). The composition is dominated by sulfate (48%) and organic species (40%). Positive Matrix Factorization (PMF) identified three key factors corresponding to a primary hydrocarbon-like organic aerosol (HOA), and two types of secondary organic aerosol: oxygenated organic aerosol (OOA) and a marine organic aerosol (MOA). The HOA factor accounts for 5% of the organic aerosol mass, which is consistent with previous findings at Villum. The OOA factor accounts for 77% of the organic aerosol mass and correlates with accumulation mode particles, which supports previous findings indicating that oxidized organic aerosols are predominantly from long-range transport during winter and spring at Villum. The MOA factor was characterized by mass spectral fragments of methane sulfonic acid (MSA) from atmospheric oxidation of dimethyl sulfide, for which reason the MOA factor is considered to be of biogenic origin. MOA accounts for 18% of the organic aerosol mass and correlates with locally produced Aitken mode particles. This indicates that biogenic processes are not only a significant source of aerosols at Villum, but MOA also appears to be formed in the vicinity of the measurement site. This local geographical origin was confirmed through air mass back trajectory modelling and source-receptor analysis. During May, air masses frequently arrived from the east, with source regions for the MOA factor and therewith MSA located in the Barents Sea and Lincoln Sea with lesser contributions from the Greenland Sea. During June, air mass origin shifted to the west, with source regions for the MOA factor and MSA shifting correspondingly to Baffin Bay and the Canadian Arctic Archipelago. While shifting transport patterns between May and June lead to shifting source regions, sea ice likely played a role as well. During May, marginal ice zones were present in the Barents Sea between Svalbard and Franz Josef Land, while during June, sea ice in the northern part of Baffin Bay retreated and sea ice in the Canadian Arctic Archipelago decreased. Although May and June experienced different transport patterns and sea ice conditions, levels of the MOA factor and MSA were similar between the months. This is likely due to similarities between marine biological activities in the Barents Sea and Baffin Bay. This research highlights the complex relationship between transport patterns, sea ice conditions, and atmospheric particle concentrations. Multiyear aerosol chemical composition from several High Arctic sites is encouraged to determine the full effects of ocean-atmosphere interactions and transport patterns on atmospheric aerosol concentrations.
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| 4. |
- Sandvik, R. M., et al.
(författare)
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Contemporary N-2 and SF6 multiple breath washout in infants and toddlers with cystic fibrosis
- 2022
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Ingår i: Pediatric Pulmonology. - : Wiley. - 8755-6863 .- 1099-0496.
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Tidskriftsartikel (refereegranskat)abstract
- Introduction Multiple breath washout (MBW) is used for early detection of cystic fibrosis (CF) lung disease, with SF6MBW commonly viewed as the reference method. The use of N2MBW in infants and toddlers has been questioned for technical and physiological reasons, but a new correction of the N(2 )signal has minimized the technical part. The present study aimed to assess the remaining differences and the contributing mechanisms for the differences between SF6 and N2MBW,corrected-such as tidal volume reduction during N-2 washout with pure O-2. Method This was a longitudinal multicenter cohort study. SF6MBW and N2MBW were performed prospectively at three CF centers in the same visits on 154 test occasions across 62 children with CF (mean age: 22.7 months). Offline analysis using identical algorithms to the commercially available program provided outcomes of N-2,N-original and N-2,N-corrected for comparison with SF6MBW. Results Mean functional residual capacity, FRCN2,corrected was 14.3% lower than FRCN2, original, and 1.0% different from FRCSF6. Lung clearance index, LCIN2,corrected was 25.2% lower than LCIN2,original, and 7.3% higher than LCISF6. Mean (SD) tidal volume decreased significantly during N2MBWcorrected, compared to SF6MBW (-13.1 ml [-30.7; 4.6], p < 0.0001, equal to -12.0% [-25.7; 1.73]), but this tidal volume reduction did not correlate to the differences between LCIN2,corrected and LCISF6. The absolute differences in LCI increased significantly with higher LCISF6 (0.63/LCISF6) and (0.23/LCISF6), respectively, for N-2,N-original and N-2,N-corrected, but the relative differences were stable across disease severity for N-2,N-corrected, but not for N-2,N-original. Conclusion Only minor residual differences between FRCN2,corrected and FRCSF6 remained to show that the two methods measure gas volumes very similar in this age range. Small differences in LCI were found. Tidal volume reduction during N2MBW did not affect differences. The corrected N2MBW can now be used with confidence in young children with CF, although not interchangeably with SF6.
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| 5. |
- Falhammar, H, et al.
(författare)
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Associations Between Antihypertensive Medications and Severe Hyponatremia: A Swedish Population-Based Case-Control Study
- 2020
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Ingår i: The Journal of clinical endocrinology and metabolism. - : The Endocrine Society. - 1945-7197 .- 0021-972X. ; 105:10
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Tidskriftsartikel (refereegranskat)abstract
- BackgroundCalcium channel blockers (CCBs), beta-receptor blockers (BBs), angiotensin-converting enzyme inhibitors (ACEIs), and angiotensin II receptor blockers (ARBs) have occasionally been reported to cause severe hyponatremia. The aim was to explore the association between CCBs, BBs, ACEIs, and ARBs and hospitalization due to hyponatremia.MethodsPatients hospitalized with a principal diagnosis of hyponatremia (n = 11 213) were compared with matched controls (n = 44 801). Linkage of national population-based registers was used to acquire data. Multivariable logistic regression adjusting for co-medications, diseases, previous hospitalizations, and socioeconomic factors was used to explore the association between hospitalization for severe hyponatremia and the use of different CCBs, BBs, ACEIs, and ARBs. Furthermore, newly initiated (≤90 days) and ongoing use were examined separately.ResultsAdjusted odds ratios (aORs) (95% confidence interval) for the investigated 4 drug classes ranged from 0.86 (0.81-0.92) for CCBs to 1.15 (1.07-1.23) for ARBs. For newly initiated drugs, aORs spanned from 1.64 (1.35-1.98) for CCBs to 2.24 (1.87-2.68) for ACEIs. In contrast, the corresponding associations for ongoing therapy were not elevated, ranging from 0.81 (0.75-0.86) for CCBs to 1.08 (1.00-1.16) for ARBs. In the CCBs subgroups, aOR for newly initiated vascular CCBs was 1.95 (1.62-2.34) whereas aOR for ongoing treatment was 0.82 (0.77-0.88).ConclusionsFor newly initiated CCBs, BBs, ACEIs, and ARBs, the risk of hospitalization due to hyponatremia was moderately elevated. In contrast, there was no evidence that ongoing treatment with investigated antihypertensive drugs increased the risk for hospitalization due to hyponatremia.
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