ORCID Profile
0000-0002-6692-0665
Current Organisation
GEOMAR Helmholtz Centre for Ocean Research Kiel
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Publisher: Wiley
Date: 04-06-2018
DOI: 10.1002/JEZ.2189
Publisher: American Geophysical Union (AGU)
Date: 11-2019
DOI: 10.1029/2019GC008275
Publisher: Informa UK Limited
Date: 09-08-2019
Publisher: Geological Society of London
Date: 2020
Publisher: American Geophysical Union (AGU)
Date: 2022
DOI: 10.1029/2021JB021997
Abstract: Although submarine landslides have been studied for decades, a persistent challenge is the integration of erse geoscientific datasets to characterize failure processes. We present a core‐log‐seismic integration study of the Tuaheni Landslide Complex to investigate intact sediments beneath the undeformed seafloor as well as post‐failure landslide deposits. Beneath the undeformed seafloor are coherent reflections underlain by a weakly‐reflective and chaotic seismic unit. This chaotic unit is characterized by variable shear strength that correlates with density fluctuations. The basal shear zone of the Tuaheni landslide likely exploited one (or more) of the low shear strength intervals. Within the landslide deposits is a widespread “Intra‐debris Reflector”, previously interpreted as the landslide's basal shear zone. This reflector is a subtle impedance drop around the boundary between upper and lower landslide units. However, there is no pronounced shear strength change across this horizon. Rather, there is a pronounced reduction in shear strength ∼10–15 m above the Intra‐debris Reflector that presumably represents an induced weak layer that developed during failure. Free gas accumulates beneath some regions of the landslide and is widespread deeper in the sedimentary sequence, suggesting that free gas may have played a role in pre‐conditioning the slope to failure. Additional pre‐conditioning or failure triggers could have been seismic shaking and associated transient fluid pressure. Our study underscores the importance of detailed core‐log‐seismic integration approaches for investigating basal shear zone development in submarine landslides.
Publisher: Elsevier BV
Date: 06-2022
Publisher: American Geophysical Union (AGU)
Date: 06-2023
DOI: 10.1029/2022JB026279
Abstract: Sub‐seabed fluid flow, gas hydrate accumulation and seafloor methane seepage are tightly interwoven processes with implications for marine bio ersity, ocean chemistry and seafloor stability. We combine long‐offset seismic reflection data with high‐resolution seismic data to investigate shallow structural deformation and its relationship to focused gas migration and hydrate accumulation in the southern Hikurangi subduction wedge. Anticlines, effective traps for focusing free gas, are characterized by both normal faults and vertical zones of hydraulic fracturing within the hydrate stability zone. The normal faults form as a result of sediment layer folding and gravitational collapse of ridges during uplift. We document both longitudinal (ridge‐parallel) and transverse (ridge‐perpendicular) extensional structures (normal faults and elongated hydraulic fracture zones) in the sub‐seafloor of anticlinal ridges. Intriguingly, gas flow through ridges close to the deformation front of the wedge exploits longitudinal structures, while ridges further inboard are characterized by gas flow along transverse structures. This highlights pronounced changes in the shallow deformation of ridges in different parts of the wedge, associated with a switching of the least and intermediate principal stress directions. It is critical to understand these shallow stress fields because they control fluid flow patterns and methane seepage out of the seafloor.
Publisher: American Geophysical Union (AGU)
Date: 09-2021
DOI: 10.1029/2020JB021489
Abstract: Focused gas migration through the gas hydrate stability zone in vertical gas conduits is a global phenomenon. The process can lead to concentrated gas hydrate formation and seafloor gas seepage, which influences seafloor bio ersity and ocean biogeochemistry. However, much is unknown about how gas and gas hydrate co‐exist within and around gas conduits. We present seismic imaging of the gas hydrate system beneath a four‐way closure anticlinal ridge at New Zealand's southern Hikurangi subduction margin. Gas has accumulated beneath the base of gas hydrate stability to a thickness of up to ∼240 m, which has ultimately led to hydraulic fracturing and propagation of a vertical gas conduit to the seafloor. Despite the existence of an array of normal faults beneath the ridge, these structures are not exploited as long‐range gas flow conduits. Directly beneath the conduit, and extending upward from the regional base of gas hydrate stability, is a broad zone characterized by both negative‐ and positive‐polarity reflections. We interpret this zone as a volume of sediment hosting both gas hydrate and free gas, that developed due to partial gas trapping beneath a mass transport deposit. Similar highly reflective zones have been identified at the bases of other gas conduits, but they are not intrinsic to all gas conduits through gas hydrate systems. We suggest that pronounced intervening sealing units within the gas hydrate stability zone determine whether or not they form.
Publisher: Springer Science and Business Media LLC
Date: 29-01-2022
DOI: 10.1007/S00455-021-10389-Y
Abstract: Dysphagia occurs commonly in the intensive care unit (ICU). Despite the clinical relevance, there is little worldwide research on prevention, assessment, evaluation, and/or treatment of dysphagia for ICU patients. We aimed to gain insight into this international knowledge gap. We conducted a multi-center, international online cross-sectional survey of adult ICUs. Local survey distribution ch ions were recruited through professional and personal networks. The survey was administered from November 2017 to June 2019 with three emails and a final telephone reminder. Responses were received from 746 ICUs (26 countries). In patients intubated > 48 h, 17% expected a > 50% chance that dysphagia would develop. This proportion increased to 43% in patients intubated > 7 days, and to 52% in tracheotomized patients. Speech-language pathologist (SLP) consultation was available in 66% of ICUs, only 4% reported a dedicated SLP. Although 66% considered a routine post-extubation dysphagia protocol important, most (67%) did not have a protocol. Few ICUs routinely assessed for dysphagia after 48 h of intubation (30%) or tracheostomy (41%). A large proportion (46%) used water swallow screening tests to determine aspiration, few (8%) used instrumental assessments (i.e., flexible endoscopic evaluation of swallowing). Swallowing exercises were used for dysphagia management by 30% of ICUs. There seems to be limited awareness among ICU practitioners that patients are at risk of dysphagia, particularly as ventilation persists, protocols, routine assessment, and instrumental assessments are generally not used. We recommend the development of a research agenda to increase the quality of evidence and ameliorate the implementation of evidence-based dysphagia protocols by dedicated SLPs.
Publisher: Cold Spring Harbor Laboratory
Date: 08-06-2020
DOI: 10.1101/2020.06.07.125443
Abstract: Sexual selection has been proposed to drive the evolution of elaborate phenotypic traits in males, which often confer success in competition or mating. However, in many species both males and females display such traits, although studies reporting selection acting in both sexes are scarce. In this study, we investigated whether plumage ornamentation is sexually selected in female and male lovely fairy-wrens Malurus amabilis, a cooperatively breeding songbird. We found that female and male plumage colour was correlated with parental quality but did not incur survival costs. We also found evidence of positive assortative mating based on plumage colour. Microsatellite analyses of paternity indicated that the lovely fairywren has high levels of extra-pair paternity, with 53% of offspring resulting from extra-pair mating. Female and male plumage colour did not predict reproductive success and female proportion of extra-pair offspring in its own nest, but less colourful males obtained higher extra-pair paternity. We argue that plumage colour may be under sex-specific selection, highlighting the importance of looking at both sexes in studies of sexual selection and ornament evolution. The current findings together with previous study, suggest that plumage colour in female and male lovely fairy-wrens appears to be an honest signal relevant in both intra and inter-sexual competition contexts.
Start Date: 2017
End Date: 2020
Funder: Marsden Fund
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