Refine
Document Type
- Article (2)
- Bachelor Thesis (1)
Is part of the Bibliography
- yes (3)
Keywords
- Balance (1)
- Calcaneus (1)
- Erosion (1)
- Gait (1)
- Intra-articular calcaneal fracture (1)
- Muscle strength (1)
- Peak torque (1)
- Plantar pressure distribution (1)
- Postural control (1)
- Proprioception (1)
Glacial-interglacial variations in CO2 and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks through the last glacial cycle (130 ka to present) using a newly compiled database of 1,063 detailed stratigraphic records of peat deposits buried by mineral sediments, as well as a global peatland model. Quantitative agreement between modeling and observations shows extensive peat accumulation before the LGM in northern latitudes (> 40 degrees N), particularly during warmer periods including the last interglacial (130 ka to 116 ka, MIS 5e) and the interstadial (57 ka to 29 ka, MIS 3). During cooling periods of glacial advance and permafrost formation, the burial of northern peatlands by glaciers and mineral sediments decreased active peatland extent, thickness, and modeled C stocks by 70 to 90% from warmer times. Tropical peatland extent and C stocks show little temporal variation throughout the study period. While the increased burial of northern peats was correlated with cooling periods, the burial of tropical peat was predominately driven by changes in sea level and regional hydrology. Peat burial by mineral sediments represents a mechanism for long-term terrestrial C storage in the Earth system. These results show that northern peatlands accumulate significant C stocks during warmer times, indicating their potential for C sequestration during the warming Anthropocene.
Fractures of the calcaneus are often associated with serious permanent disability, a considerable reduction in quality of life, and high socio-economic cost. Although some studies have already reported changes in plantar pressure distribution after calcaneal fracture, no investigation has yet focused on the patient's strength and postural control.
Method: 60 patients with unilateral, operatively treated, intra-articular calcaneal fractures were clinically and biomechanically evaluated >1 year postoperatively (physical examination, SF-36, AOFAS score, lower leg isokinetic strength, postural control and gait analysis including plantar pressure distribution). Results were correlated to clinical outcome and preoperative radiological findings (Bohler angle, Zwipp and Sanders Score).
Results: Clinical examination revealed a statistically significant reduction in range of motion at the tibiotalar and the subtalar joint on the affected side. Additionally, there was a statistically significant reduction of plantar flexor peak torque of the injured compared to the uninjured limb (p < 0.001) as well as a reduction in postural control that was also more pronounced on the initially injured side (standing duration 4.2 +/- 2.9 s vs. 7.6 +/- 2.1 s, p < 0.05). Plantar pressure measurements revealed a statistically significant pressure reduction at the hindfoot (p = 0.0007) and a pressure increase at the midfoot (p = 0.0001) and beneath the lateral forefoot (p = 0.037) of the injured foot.
There was only a weak correlation between radiological classifications and clinical outcome but a moderate correlation between strength differences and the clinical questionnaires (CC 0.27-0.4) as well as between standing duration and the clinical questionnaires. Although thigh circumference was also reduced on the injured side, there was no important relationship between changes in lower leg circumference and strength suggesting that measurement of leg circumference may not be a valid assessment of maximum strength deficits. Self-selected walking speed was the parameter that showed the best correlation with clinical outcome (AOFAS score).
Conclusion: Calcaneal fractures are associated with a significant reduction in ankle joint ROM, plantar flexion strength and postural control. These impairments seem to be highly relevant to the patients. Restoration of muscular strength and proprioception should therefore be aggressively addressed in the rehabilitation process after these fractures.
Durch das anhaltende Rückschmelzen von Gletschern werden mehr Sedimentdepots freigesetzt, wodurch diese anfälliger für Erosion werden. Erhöhte Sedimentaustragsraten gefährden die Wasserqualität sowie die Wasserversorgung durch Stauraumverlandung. Um diese Gefahren und deren Abläufe besser verstehen zu können, müssen Erosionsprozesse vor allem in hochalpinen Einzugsgebieten erforscht werden. In dieser Bachelorarbeit wurden Sedimentkonzentrationen sowie weitere Umgebungsvariablen (Abfluss, Niederschlag und Temperatur) im Rofental, Ötztaler Alpen und in einem stark vergletscherten Teileinzugsgebiet des Rofentals gemessen. Um den Zusammenhang zwischen der Sedimentkonzentration und den gemessenen Umgebungsbedingungen zu ermitteln, wurde das Quantile Regression Forest Modell verwendet. Dabei wurden die Variablen zu unterschiedlichen Zeitstufen aggregiert, wodurch vergangene hydroklimatische Bedingungen berücksichtigt werden konnten. Mit der Kenntnis über den Einfluss der verschiedenen Einflussfaktoren konnte die Sedimentkonzentration rückwirkend mithilfe eines Monte Carlo Ansatzes kontinuierlich modelliert werden, wodurch Aussagen über die jährlichen Sedimentexportraten getätigt werden konnten. Weiterhin wurde auch die Trübung, welche als Indikator für die Sedimentkonzentration angesehen werden kann, gemessen. Durch die Bestimmung der Korrelation zwischen modellierten Daten und der gemessenen Trübung konnte der Aussagegehalt des Modells beurteilt werden. Es konnte gezeigt werden, dass das Quantile Regression Forest Modell geeignet ist, um die Sedimentdynamik im Rofental zu rekonstruieren. Es stellte sich weiterhin heraus, dass der Abfluss in beiden Untersuchungsgebieten den größten Einfluss auf die Sedimentdynamik hat, wobei sich die Relevanz verschiedener Variablen in beiden Untersuchungsgebieten stark unterschied. Gemessene Trübungsdaten und die modellierten Sedimentkonzentrationen korrelierten stark positiv, wobei Murgänge, Messfehler und die Anzapfung neuer Sedimentdepots zur Verschlechterung der Modellgüte führten.