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  • 1
    Artikel
    Artikel
    Origin of Indian Ocean Seamount Province by shallow recycling of continental lithosphere (2011)
    Dazugehörige Bände
    Details Verfügbarkeit
    In: Nature geoscience, London : Nature Publishing Group, 2008, 4(2011), 12, Seite 883-887, 1752-0894
    In: volume:4
    In: year:2011
    In: number:12
    In: pages:883-887
    Beschreibung / Inhaltsverzeichnis: The origin of the Christmas Island Seamount Province in the northeast Indian Ocean is enigmatic. The seamounts do not form the narrow, linear and continuous trail of volcanoes that would be expected if they had formed above a mantle plume1, 2. Volcanism above a fracture in the lithosphere3 is also unlikely, because the fractures trend orthogonally with respect to the east–west trend of the Christmas Island chain. Here we combine 40Ar/39Ar age, Sr, Nd, Hf and high-precision Pb isotope analyses of volcanic rocks from the province with plate tectonic reconstructions. We find that the seamounts are 47–136 million years old, decrease in age from east to west and are consistently 0–25 million years younger than the underlying oceanic crust, consistent with formation near a mid-ocean ridge. The seamounts also exhibit an enriched geochemical signal, indicating that recycled continental lithosphere was present in their source. Plate tectonic reconstructions show that the seamount province formed at the position where West Burma began separating from Australia and India, forming a new mid-ocean ridge. We propose that the seamounts formed through shallow recycling of delaminated continental lithosphere entrained in mantle that was passively upwelling beneath the mid-ocean ridge. We conclude that shallow recycling of continental lithosphere at mid-ocean ridges could be an important mechanism for the formation of seamount provinces in young ocean basins.
    Materialart: Artikel
    Seiten: Ill., Kt.
    ISSN: 1752-0894
    DOI: 10.1038/ngeo1331
    Sprache: Englisch
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  • 2
    Digitale Medien
    Digitale Medien
    CT-gesteuerte Schneid-Saug-Biopsie zur minimal invasiven histologischen Abklärung pathologischer Thoraxbefunde (1999)
    Springer
    Zeitschrift für Herz-, Thorax- und Gefässchirurgie 13 (1999), S. 133-138 
    Details
    ISSN: 0930-9225
    Schlagwort(e): Schlüsselwörter Computertomographie – Thorax – Interventionen – Schneid-Saug-Biopsie ; Key words Computer tomography – thorax interventions – carve-suction biopsy
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Beschreibung / Inhaltsverzeichnis: Summary Problem: An investigation into CT-controlled carve-suction biopsy for a histological clarification of indefinite intrathoracic masses. Materials and Method: 143 CT-controlled interventions were performed on 102 patients. For histological evaluation purposes, tissue was taken under application of the carva-suction biopsy method (16–18 gage). The lesions with a diameter of 5–70 mm were located in the mediastinum (25%), were close to the thoracic wall/pleural (40%) and intrapulmonary (35%). Results: 92.2% (94/102) of the interventions provided histologically utilizable material in at least one biopsy specimen. The clinical suspected diagnosis was confirmed 78 times (76.5%), while a different discase was evident 16 times (15.7%). In 8 cases, a diagnosis was not possible (7.8%). The total complication rate was 21.6%. The following were observed: 18 pneumothoraxes, 2 hemothoraxes, and 2 patients who demonstrated a hemoptysis. In 4/102 patients (3.9%) complications arose which had to be treated therapeutically. Two-sided complications were not observed. Conclusions: The CT-controlled carve-suction biopsy can be employed histologically to clarify indefinite intrathoracic findings with a high degree of certainty and justifiable complication rates. In addition to this, the minimally invasive procedure helps to reduce costs.
    Notizen: Zusammenfassung Fragestellung: Bewertet wird die CT-gesteuerte Schneid-Saug-Biopsie zur histologischen Abklärung unklarer intrathorakaler Raumforderungen. Material und Methode: Bei 102 Patienten wurden 143 CT-gesteuerte Interventionen durchgeführt. Zur histologischen Beurteilung wurde Gewebe in Schneid-Saug-Biopsie-Technik (16–18 Gage) entnommen. Die Läsionen waren 5–70 mm groß, 25% lagen mediastinal, 40% thoraxwandnah/pleural und 35% intrapulmonal. Ergebnisse: 92,2% (94/102) der Interventionen erbrachten in mindestens einer entnommenen Gewebeprobe histologisch verwertbares Material. Die klinische Verdachtsdiagnose wurde 78mal (76,5%) bestätigt, 16mal (15,7%) wurde eine andere Erkrankung nachgewiesen. 8mal ließ sich keine Diagnose stellen (7,8%). Die Komplikationsrate betrug 21,6% (18 Pneumothoraces, 2 Hämatothoraces und 2 Patienten mit Hämoptoe). Bei 4/102 Patienten (3,9%) traten therapiebedürftige Komplikationen auf. Schlußfolgerungen: Mit der CT-gesteuerten Schneid-Saug-Biopsie lassen sich unklare intrathorakale Befunde mit hoher Treffsicherheit und vertretbaren Komplikationen abklären.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003980050070
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  • 3
    Digitale Medien
    Digitale Medien
    The influence of tube voltage, X-ray exposure rate and thickness of filter material on image quality with dual-energy subtraction imaging in chest diagnostics (1992)
    Springer
    European radiology 2 (1992), S. 258-263 
    Details
    ISSN: 1432-1084
    Schlagwort(e): One-shot dual-energy subtraction imaging ; Laser-stimulated luminescence imaging plates ; Energy separation ; Computed radiography ; Chest diagnostics
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract Digital luminescent radiography enables dual-energy subtraction imaging, because this computed system allows susbtraction of imaging data and image post processing, as for example special windowing or edge enhancement. In a special cassette a copper filter is placed between two imaging plates for energy separation by a single X-ray exposure. Image post-processing with subtraction of imaging data permits the elimination of either skeleton or soft tissue structures. The influence of filter thickness, tube voltage and the X-ray exposure dosage on image quality is examined by the use of an anthropomorphic quality is examined by the use of an anthropomorphic phantom of the chest. According to our initial results dual energy subtraction imaging in one-shot-technique seems to be useful in the diagnostics of skeletal lesions and especially pulmonary nodules.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00595841
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  • 4
    Digitale Medien
    Digitale Medien
    Digital luminescent radiography for diagnosis of skeletal injuries (1992)
    Springer
    European radiology 2 (1992), S. 542-547 
    Details
    ISSN: 1432-1084
    Schlagwort(e): Digital luminescence radiography ; Skeletal diagnosis ; Traumatology ; Standard digital images ; Image post-processing ; Creation of artefacts
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract In the course of a comparative study 231 patients with traumatic lesions in skeletal and soft tissue areas were X-rayed using conventional film radiography and digital luminescence radiography (DLR). The results were evaluated by radiologists and traumatologists on the basis of optimised image post-processing in addition to the standard digital presentations. The imaging quality of compacta, spongiosa, soft tissues, fracture lines and osteosynthesis material was assessed in comparison with the screen-film images. Whereas the standard digital presentation in the “conventionally adjusted” imaging mode was inferior to the screen-film radiograph, the “edge-enhanced” standard presentation proved to be advantageous in the imaging of soft tissues (frequency of first-place ratings: DLR conventional 6%, screen-film system 21%, DLR edge-enhanced 31%). In the overall evaluation high-frequency filtered inverse image post-processing showed the highest diagnostic potential (frequency of first-place ratings: 41%). A conclusive assessment of metal implants is hindered by overshoot artefacts and can only be achieved through time-consuming post-processing of the stored image data.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00187549
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  • 5
    Digitale Medien
    Digitale Medien
    Unsharp masking of low-dosed digital luminiscence radiographs: results of a receiver operating characteristics analysis (1996)
    Springer
    European radiology 6 (1996), S. 526-531 
    Details
    ISSN: 1432-1084
    Schlagwort(e): Chest diagnostics ; Projection radiography ; High-amplification screen-film systems ; Digital luminiscence radiography ; Filter kernel
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract The extent to which the diagnostic performance of low-dosed storage phosphors can be improved by suitable image postprocessing was investigated. Storage phosphors radiographs and conventional 200- and 400-speed screen-film combinations of an antropomorphic chest phantom with simulated nodules and linear structures were compared. The detection of test bodies was determined in an ROC analysis based on 16 200 individual observations. The two analog screen-film systems did not differ significantly. As far as the storage phosphor radiographs are concerned, a higher diagnostic performance was achieved with a large filter kernel (S 40), whereas small filter kernels and edge-enhanced imaging modes reduced the detection of detail. The image quality of low-dosed storage phosphors is thus similar to high-amplification screen-film combinations if large filter kernels are used in postprocessing of the image.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00182488
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  • 6
    Digitale Medien
    Digitale Medien
    Detection of radiographic findings in lung fibrosis using storage phosphor plates (1997)
    Springer
    European radiology 7 (1997), S. 576-582 
    Details
    ISSN: 1432-1084
    Schlagwort(e): Key words: Digital radiography ; Storage phosphorous plates ; Image postprocessing ; Chest radiography ; Lung fibrosis
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Medizin
    Notizen: Abstract. The aim of this work was to examine the influence of the filter kernel size on the detectability of differing radiological findings in interstitial lung disease. In 97 patients with confirmed pulmonary fibrosis chest radiographs were obtained with a film-screen system of speed class 200 and with correspondingly exposed storage phosphorous plates. The size of the filter kernel used for the image postprocessing varied between sigma 5 and sigma 70. The detectability of interstitial lung changes was evaluated independently by eight readers on the basis of a defined rating system. The results were analysed using multifactorial analysis of variance with Scheffé test at a significance level of p = 0.05. Small kernel sizes (S 5, S 10) combined with high edge enhancement were only of benefit in the imaging of septal lines, but reduced the detectability of nodular and reticular structures. Good detail detectability of both micronodules and septal lines was obtained with a medium kernel size of sigma 40. Storage phosphor radiography utilizing the appropriate choice of postprocessing parameters provides equivalent image quality for evaluating interstitial lung changes compared with a modern film-screen technique.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/s003300050209
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  • 7
    Digitale Medien
    Digitale Medien
    Changes in muscle blood flow after smoking a cigarette determined by a new noninvasive method (1989)
    Springer
    European journal of clinical pharmacology 37 (1989), S. 517-520 
    Details
    ISSN: 1432-1041
    Schlagwort(e): nicotine ; epinephrine ; cigarette smoking ; total forearm blood flow ; muscle blood flow ; plethysmography
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Chemie und Pharmazie , Medizin
    Notizen: Summary In 9 healthy subjects the effect of smoking one cigarette (nicotine content 0.9 mg) on blood pressure, heart rate and total and muscle blood flow in the forearm was measured. Blood flow was measured by a new noninvasive plethysmographic method that simultaneously gives quantitative data about total and muscle blood flow. Smoking the cigarette did not significantly affect blood pressure or heart rate. Total blood flow in the forearm did not change but the flow to the muscle was increased and resistance in this vascular bed was decreased. The pattern of haemodynamic changes in the forearm indicates that epinephrine may be the mediator of the circulatory effects of nicotine.
    Materialart: Digitale Medien
    URL: http://dx.doi.org/10.1007/BF00558134
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  • 8
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    Developing community-based scientific priorities and new drilling proposals in the Southern Indian and Southwest Pacific oceans (2018)
    Copernicus Publications
    In:  EPIC3Scientific Drilling, Copernicus Publications, 24, pp. 61-70, ISSN: 1816-8957
    Details
    Publikationsdatum: 2018-10-22
    Beschreibung: An International Ocean Discovery Program (IODP) workshop was held at Sydney University, Australia, from 13 to 16 June 2017 and was attended by 97 scientists from 12 countries. The aim of the workshop was to investigate future drilling opportunities in the eastern Indian Ocean, southwestern Pacific Ocean, and the Indian and Pacific sectors of the Southern Ocean. The overlying regional sedimentary strata are underexplored relative to their Northern Hemisphere counterparts, and thus the role of the Southern Hemisphere in past global environmental change is poorly constrained. A total of 23 proposal ideas were discussed, with 12 of these deemed mature enough for active proposal development or awaiting scheduled site survey cruises. Of the remaining 11 proposals, key regions were identified where fundamental hypotheses are testable by drilling, but either site surveys are required or hypotheses need further development. Refinements are anticipated based upon regional IODP drilling in 2017/2018, analysis of recently collected site survey data, and the development of site survey proposals. We hope and expect that this workshop will lead to a new phase of scientific ocean drilling in the Australasian region in the early 2020s.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
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  • 9
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    Necessary Conditions for Warm Inflow Toward the Filchner Ice Shelf, Weddell Sea (2020)
    Wiley
    In:  EPIC3Geophysical Research Letters, Wiley, 47(22), pp. 1-11, ISSN: 0094-8276
    Details
    Publikationsdatum: 2020-11-18
    Beschreibung: Understanding changes in Antarctic ice shelf basal melting is a major challenge for predicting future sea level. Currently, warm Circumpolar Deep Water surrounding Antarctica has limited access to the Weddell Sea continental shelf; consequently, melt rates at Filchner‐Ronne Ice Shelf are low. However, large‐scale model projections suggest that changes to the Antarctic Slope Front and the coastal circulation may enhance warm inflows within this century. We use a regional high‐resolution ice shelf cavity and ocean circulation model to explore forcing changes that may trigger this regime shift. Our results suggest two necessary conditions for supporting a sustained warm inflow into the Filchner Ice Shelf cavity: (i) an extreme relaxation of the Antarctic Slope Front density gradient and (ii) substantial freshening of the dense shelf water. We also find that the on‐shelf transport over the western Weddell Sea shelf is sensitive to the Filchner Trough overflow characteristics.
    Repository-Name: EPIC Alfred Wegener Institut
    Materialart: Article , isiRev
    Format: application/pdf
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  • 10
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    Dynamic topography of passive continental margins and their hinterlands since the Cretaceous (2018)
    Elsevier
    In:  Gondwana Research, 53 . pp. 225-251.
    Details
    Publikationsdatum: 2019-01-02
    Beschreibung: Even though it is well accepted that the Earth's surface topography has been affected by mantle-convection induced dynamic topography, its magnitude and time-dependence remain controversial. The dynamic influence to topographic change along continental margins is particularly difficult to unravel, because their stratigraphic record is dominated by tectonic subsidence caused by rifting. We follow a three-fold approach to estimate dynamic topographic change along passive margins based on a set of seven global mantle convection models. We first demonstrate that a geodynamic forward model that includes adiabatic and viscous heating in addition to internal heating from radiogenic sources, and a mantle viscosity profile with a gradual increase in viscosity below the mantle transition zone, provides a greatly improved match to the spectral range of residual topography end-members as compared with previous models at very long wavelengths (spherical degrees 2–3). We then combine global sea level estimates with predicted surface dynamic topography to evaluate the match between predicted continental flooding patterns and published paleo-coastlines by comparing predicted versus geologically reconstructed land fractions and spatial overlaps of flooded regions for individual continents since 140 Ma. Modelled versus geologically reconstructed land fractions match within 10% for most models, and the spatial overlaps of inundated regions are mostly between 85% and 100% for the Cenozoic, dropping to about 75–100% in the Cretaceous. Regions that have been strongly affected by mantle plumes are generally not captured well in our models, as plumes are suppressed in most of them, and our models with dynamically evolving plumes do not replicate the location and timing of observed plume products. We categorise the evolution of modelled dynamic topography in both continental interiors and along passive margins using cluster analysis to investigate how clusters of similar dynamic topography time series are distributed spatially. A subdivision of four clusters is found to best reveal end-members of dynamic topography evolution along passive margins and their hinterlands, differentiating topographic stability, long-term pronounced subsidence, initial stability over a dynamic high followed by moderate subsidence and regions that are relatively proximal to subduction zones with varied dynamic topography histories. Along passive continental margins the most commonly observed process is a gradual motion from dynamic highs towards lows during the fragmentation of Pangea, reflecting the location of many passive margins now over slabs sinking in the lower mantle. Our best-fit model results in up to 500 (± 150) m of total dynamic subsidence of continental interiors while along passive margins the maximum predicted dynamic topographic change over 140 million years is about 350 (± 150) m of subsidence. Models with plumes exhibit clusters of transient passive margin uplift of about 200 ± 200 m, but are mainly characterised by long-term subsidence of up to 400 m. The good overall match between predicted dynamic topography to geologically mapped paleo-coastlines makes a convincing case that mantle-driven topographic change is a critical component of relative sea level change, and indeed the main driving force for generating the observed geometries and timings of large-scale continental inundation through time.
    Materialart: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.gr.2017.04.028
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