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  • 1
    Publication Date: 2023-02-23
    Type: Conference or Workshop Item , NonPeerReviewed
    Format: text
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  • 2
    Publication Date: 2024-02-07
    Description: Volcanic islands export clastic material to their surrounding oceans by explosive eruptions, lava emissions, biogenic production on their shelves, and failure of their slopes, amongst other processes. This raises the question of whether geological events (in particular, eruptions and landslides) can be detected offshore and dated, and whether any relationships (for example, with climate changes) can be revealed using sediment cores. The volcanically active central Azorean islands (Faial, Pico, São Jorge, and Terceira), with their neighboring submarine basins, are potentially good candidates for such an analysis. Here, chronostratigraphies of four gravity cores collected amongst the islands are constructed based on twelve radiocarbon dates and two dates derived by geochemically correlating primary volcaniclastic turbidites with ignimbrites on Faial and Terceira Islands. Age-depth models are built from the hemipelagic intervals to estimate individual turbidite dates. Volumes of turbidites are modeled by multiplying basin areas with bed thickness, allowing for various turbidite thinning rates and directions. The volumes of landslide-generated turbidites are only comparable with the largest volumes of their adjacent upper-slope submarine landslide valleys; therefore, such turbidites in the cores likely derive from these largest landslides. Emplacement intervals between turbidites originating from both landslides and pyroclastic density currents are found to be mostly a few thousand years. Frequencies of landslide-generated turbidites and hemipelagic sedimentation rates were both highest in the past 8 k.y. compared to preceding periods up to 50 k.y. High hemipelagic sedimentation rates are interpreted to be related to sea-level rise, allowing more shelf bioproduction and release of particles by coastal erosion. The coincident increased frequencies of submarine landslides may also be associated with the increased sediment supply from the islands, resulting in a more rapid build-up of unstable sediments on submarine slopes. Notably, the emplacement frequencies of turbidites of pyroclastic density current origins do not suggest the decreased eruption frequency toward the Holocene that has been found elsewhere.
    Type: Article , PeerReviewed , info:eu-repo/semantics/article
    Format: other
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  • 3
    Publication Date: 2023-01-19
    Description: Geological histories of volcanic ocean islands can be revealed by the sediments shed by them. Hence there is an interest in studying cores of volcaniclastic sediments that are particularly preserved in the many flat-floored basins lying close to the Azores islands. We analyse four gravity cores collected around the central group of the islands. Three sedimentary facies (F1-F2a, F2b) are recognized based on visual core logging, particle morphometric and geochemical analyses. F1 is clay-rich hemipelagite comprising homogeneous mud with mottled structures from bioturbation. F2a and F2b are both clay-poor volcaniclastic deposits, which are carbonate-rich and carbonate-poor, respectively. More biogenic carbonate in F2a reflects the incorporation of unconsolidated calcareous material from island shelves or bioturbation. Within F2a and F2b we identify deposits emplaced by pyroclastic fallout, primary or secondary turbidity currents by combining multiple information from lithological composition, sedimentary structures, chemical composition of volcanic glass shards and morphometric characteristics of volcanic particles. Primary volcaniclastic sediments were found in all four cores, echoing activity known to have occurred up to historical times on the adjacent islands. These preliminary results suggest that greater details of geological events could be inferred for other volcanic islands by adopting a similar approach to core analysis.
    Type: Book chapter , NonPeerReviewed , info:eu-repo/semantics/bookPart
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  • 4
    Publication Date: 2012-12-05
    Description: Langmuir DOI: 10.1021/la303501r
    Print ISSN: 0743-7463
    Electronic ISSN: 1520-5827
    Topics: Chemistry and Pharmacology
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  • 5
    Publication Date: 2015-08-29
    Description: Background: The efficacy and safety of using cervical arthroplasty for degenerative disc disease have been demonstrated by prospective, randomized and controlled clinical trials. However, there are scant data on using cervical arthroplasty for traumatic disc herniation. Therefore, this study aimed to investigate the outcomes of patients who underwent cervical arthroplasty for traumatic disc herniation. Methods: This cohort included patients who were admitted through the emergency department for trauma. Only patients who had newly-onset, one- or two-level cervical disc disease causing radiculopathy or myelopathy were identified. None of these patients had previously sought for medical attention for such problems. Those patients who had severe spinal cord injury (i.e. American Spinal Injury Association scale A, B or C) or severe myelopathy (i.e. Nurick scale 4 or 5), bony fracture, dislocation, perched facet, kyphotic deformity, or instability were also excluded. An age- and sex-matched one-to-one comparison was made between patients who underwent cervical arthroplasty, on the one hand, and anterior cervical discectomy and fusion (ACDF). Results: A total of 30 trauma patients (15 in the arthroplasty group and 15 in the ACDF group) were analyzed, with a mean follow-up of 29.6 months. The demographic data were similar. Post-operation, the arthroplasty group had significant improvement in VAS of neck and arm pain, JOA, and NDI when compared to their pre-operation status. Similarly, the ACDF group also improved significantly after the operation. There were no differences between the two groups in post-operative VAS neck and arm pain, and JOA scores. The arthroplasty group maintained a range of motion in the indexed levels and had better NDI scores at 6-months post-operation than the ACDF group. Conclusions: For selected patients (i.e. no spinal cord injury, no fracture, and no instability) with traumatic cervical disc herniation, cervical arthroplasty yields similar improvement in clinical outcomes to ACDF and preserves segmental mobility.
    Electronic ISSN: 1471-2474
    Topics: Medicine
    Published by BioMed Central
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