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- Klocker, A., et al.
(författare)
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Generation of the Internal Pycnocline in the Subpolar Southern Ocean by Wintertime Sea Ice Melting
- 2023
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Ingår i: Journal of Geophysical Research-Oceans. - : American Geophysical Union (AGU). - 2169-9275 .- 2169-9291. ; 128:3
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Tidskriftsartikel (refereegranskat)abstract
- The ocean's internal pycnocline is a layer of elevated stratification that separates the well-ventilated upper ocean from the more slowly renewed deep ocean. Despite its pivotal role in organizing ocean circulation, the processes governing the formation of the internal pycnocline remain little understood. Classical theories on pycnocline formation have been couched in terms of temperature and it is not clear how the theory applies in the high-latitude Southern Ocean, where stratification is dominated by salinity. Here we assess the mechanisms generating the internal pycnocline at southern high latitudes through the analysis of a high-resolution, realistic, global sea ice-ocean model. We show evidence suggesting that the internal pycnocline's formation is associated with sea ice-ocean interactions in two distinct ice-covered regions, fringing the Antarctic continental slope and the winter sea-ice edge. In both areas, winter-persistent sea-ice melt creates strong, salinity-based stratification at the base of the winter mixed layer. The resulting sheets of high stratification subsequently descend into the ocean interior at fronts of the Antarctic Circumpolar Current, and connect seamlessly to the internal pycnocline in areas further north in which pycnocline stratification is determined by temperature. Our findings thus suggest an important role of localized sea ice-ocean interactions in configuring the vertical structure of the Southern Ocean.
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- Gratl, A, et al.
(författare)
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Treatment options of crural pseudoaneurysms
- 2014
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Ingår i: VASA. Zeitschrift fur Gefasskrankheiten. - : Hogrefe Publishing Group. - 0301-1526. ; 43:3, s. 209-215
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Tidskriftsartikel (refereegranskat)abstract
- Background: Pseudoaneurysms (PAs) of crural arteries represent rare complications of vascular interventions or surgery. Management of crural PAs includes different treatment options, conservative treatment as well as open surgery or endovascular procedures. We reviewed our experience. Patients and methods: We retrospectively analysed all patients who were diagnosed with crural PAs since 2003. We evaluated etiology, treatment and outcome. Endpoints were target vessel patency, vascular re-intervention and limb loss. Results: A total of 30 patients were diagnosed with crural PAs. PA was caused by vascular intervention in 27 patients (90 %): open balloon thrombectomy (n = 25), subfascial endoscopic perforator vein surgery (n = 1) and transcutaneous catheter-assisted thrombus aspiration (n = 1). In 3 patients (10 %) it was caused by orthopaedic surgical procedures. Location of crural PAs were peroneal artery (n = 11; 36.7 %), posterior tibial artery (n = 10; 33.3 %), anterior tibial artery (n = 5; 16.7 %), and tibioperoneal trunk (n = 4; 13.3 %). Treatment of crural PAs included open surgery (n = 3; 10 %), endovascular procedures (n = 13; 43.3 %) such as endograft implantation (n = 9) or coil embolisation (n = 4), and conservative management (n = 14; 46.7 %). After a median follow-up period of 7 months (range: 0 - 46 months) 8 of 9 endografts were occluded, in none of these patients a minor or a major amputation was necessary. None of the surgically, endovascularly and conservatively treated patients needed a re-intervention for crural PA. A major amputation was necessary in 4 patients due to progression of peripheral arterial disease; none was a directly consequence of the crural PA. Conclusions: Crural PAs are mainly caused by vascular intervention, most frequently by catheter thrombectomy. As a consequence, we recommend fluoroscopic-assisted balloon thrombectomy over a guide wire as routine technique. In many cases of crural PAs, conservative management is sufficient. The choice of treatment of crural PAs depends on size, location and associated symptoms. Endovascular treatment using endografts is limited by poor long-term patency.
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