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- Blomquist, B. W., et al.
(författare)
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Wind Speed and Sea State Dependencies of Air-Sea Gas Transfer : Results From the High Wind Speed Gas Exchange Study (HiWinGS)
- 2017
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Ingår i: Journal of Geophysical Research - Oceans. - 2169-9275 .- 2169-9291. ; 122:10, s. 8034-8062
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Tidskriftsartikel (refereegranskat)abstract
- A variety of physical mechanisms are jointly responsible for facilitating air-sea gas transfer through turbulent processes at the atmosphere-ocean interface. The nature and relative importance of these mechanisms evolves with increasing wind speed. Theoretical and modeling approaches are advancing, but the limited quantity of observational data at high wind speeds hinders the assessment of these efforts. The HiWinGS project successfully measured gas transfer coefficients (k(660)) with coincident wave statistics under conditions with hourly mean wind speeds up to 24 m s(-1) and significant wave heights to 8 m. Measurements of k(660) for carbon dioxide (CO2) and dimethylsulfide (DMS) show an increasing trend with respect to 10 m neutral wind speed (U-10N), following a power law relationship of the form: k660CO2 approximate to U10N1.68 and k660dms approximate to U10N1.33. Among seven high wind speed events, CO2 transfer responded to the intensity of wave breaking, which depended on both wind speed and sea state in a complex manner, with k660CO2 increasing as the wind sea approaches full development. A similar response is not observed for DMS. These results confirm the importance of breaking waves and bubble injection mechanisms in facilitating CO2 transfer. A modified version of the Coupled Ocean-Atmosphere Response Experiment Gas transfer algorithm (COAREG ver. 3.5), incorporating a sea state-dependent calculation of bubble-mediated transfer, successfully reproduces the mean trend in observed k(660) with wind speed for both gases. Significant suppression of gas transfer by large waves was not observed during HiWinGS, in contrast to results from two prior field programs.
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- Heedman, Per-Anders, et al.
(författare)
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Palliation of Malignant Biliary Obstruction: Adverse Events are Common after Percutaneous Transhepatic Biliary Drainage
- 2018
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Ingår i: Scandinavian Journal of Surgery. - : SAGE PUBLICATIONS LTD. - 1457-4969 .- 1799-7267. ; 107:1, s. 48-53
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Tidskriftsartikel (refereegranskat)abstract
- Background and Aim: Endoscopic stents in the common bile duct is the first treatment choice to alleviate symptoms of biliary obstruction due to malignant disease. When endoscopic stenting fails in palliative patients, one option is to use a percutaneous transhepatic biliary drainage, but it is not clear whether and how it can reduce the symptom load. The aim of this study was to evaluate benefits and disadvantages of percutaneous transhepatic biliary drainage in palliative care. Material and Methods: Inclusion criteria were malignant disease and bilirubin 26 mu mol/L in plasma. A structured protocol for obtaining data from the medical records was used. Data were collected from the time of last computed tomography scan before the percutaneous transhepatic biliary drainage was placed and during 14days afterward. Results and Conclusion: Inclusion criteria were fulfilled in 140 patients. Median age was 70years (33-91years). Some 126 patients had a remaining external percutaneous transhepatic biliary drainage. Jaundice was the initial symptom in 62 patients (44%). Within the first week after percutaneous transhepatic biliary drainage, the bilirubin decreased from 237 mu mol/L (31-634) to 180 mu mol/L (17-545). Only 25% reached a level below the double upper reference value. Pruritus occurred in 27% before the percutaneous transhepatic biliary drainage, but the bilirubin value did not differ from patients without pruritus. However, the pruritus was relieved in 56% with percutaneous transhepatic biliary drainage. Antibiotic prophylaxis protected to some extent from infectious complications. Adverse events were common and early mortality was high (16% within 14days). Jaundice should not by itself be an indication for percutaneous transhepatic biliary drainage for palliation except when the aim is to prepare the patient for chemotherapy. It is mandatory that the patients are informed carefully about what can be expected regarding the positive effects and the risks of adverse events.
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