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  • 1
    Electronic Resource
    Electronic Resource
    Polyphase zircon in ultrahigh-temperature granulites (Rogaland, SW Norway): constraints for Pb diffusion in zircon (2002)
    Oxford, UK : Blackwell Science Inc
    Journal of metamorphic geology 20 (2002), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: SHRIMP U–Pb ages have been obtained for zircon in granitic gneisses from the aureole of the Rogaland anorthosite–norite intrusive complex, both from the ultrahigh temperature (UHT; 〉900 °C pigeonite-in) zone and from outside the hypersthene-in isograd. Magmatic and metamorphic segments of composite zircon were characterised on the basis of electron backscattered electron and cathodoluminescence images plus trace element analysis. A sample from outside the UHT zone has magmatic cores with an age of 1034 ± 7 Ma (2σ, n = 8) and 1052 ± 5 Ma (1σ, n = 1) overgrown by M1 metamorphic rims giving ages between 1020 ± 7 and 1007 ± 5 Ma. In contrast, samples from the UHT zone exhibit four major age groups: (1) magmatic cores yielding ages over 1500 Ma (2) magmatic cores giving ages of 1034 ± 13 Ma (2σ, n = 4) and 1056 ± 10 Ma (1σ, n = 1) (3) metamorphic overgrowths ranging in age between 1017 ± 6 Ma and 992 ± 7 Ma (1σ) corresponding to the regional M1 Sveconorwegian granulite facies metamorphism, and (4) overgrowths corresponding to M2 UHT contact metamorphism giving values of 922 ± 14 Ma (2σ, n = 6). Recrystallized areas in zircon from both areas define a further age group at 974 ± 13 Ma (2σ, n = 4). This study presents the first evidence from Rogaland for new growth of zircon resulting from UHT contact metamorphism. More importantly, it shows the survival of magmatic and regional metamorphic zircon relics in rocks that experienced a thermal overprint of c. 950 °C for at least 1 Myr. Magmatic and different metamorphic zones in the same zircon are sharply bounded and preserve original crystallization age information, a result inconsistent with some experimental data on Pb diffusion in zircon which predict measurable Pb diffusion under such conditions. The implication is that resetting of zircon ages by diffusion during M2 was negligible in these dry granulite facies rocks. Imaging and Th/U–Y systematics indicate that the main processes affecting zircon were dissolution-reprecipitation in a closed system and solid-state recrystallization during and soon after M1.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1525-1314.2002.00400.x
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  • 2
    Electronic Resource
    Electronic Resource
    Exhumation of the lower crust during crustal shortening: an Alice Springs (380 Ma) age for a prograde amphibolite facies shear zone in the Strangways Metamorphic Complex (central Australia) (2000)
    Oxford, UK : Blackwell Science Inc
    Journal of metamorphic geology 18 (2000), S. 0 
    Details
    ISSN: 1525-1314
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Foliated garnet-bearing amphibolites occur within the West Bore Shear Zone, cutting through granulite facies gneisses of the Strangways Metamorphic Complex. In the amphibolites, large euhedral garnet (up to 3 cm) occurs within fine-grained recrystallized leucocratic diffusion haloes of plagioclase–quartz. The garnet and their haloes include a well-developed vertical foliation, also present in the matrix. This foliation is the same as that cutting through the unconformably overlying Neoproterozoic Heavitree Quartzite. The textures indicate syn- to late kinematic growth of the amphibolite facies mineral assemblages.All mineral assemblages record an arrested prograde reaction history. Noteworthy is the growth of garnet at the expense of hornblende and plagioclase, and the breakdown of staurolite–hornblende to give plagioclase–gedrite. These dehydration reactions indicate increasing P–T  conditions during metamorphism, and suggest heating towards the end of a period of intense deformation. Temperature estimates for the garnet–amphibolite and related staurolite–hornblende assemblages from the shear zone are about 600 °C. Pressure is estimated at about 5 kbar.An Sm–Nd isochron gives an age of 381±7 Ma for the peak metamorphism and associated deformation. This age determination confirms that amphibolite facies conditions prevailed during shear zone development within the Strangways Metamorphic Complex during the Alice Springs Orogeny. These temperature conditions are significantly higher than those expected at this depth assuming a normal geothermal gradient. The Alice Springs Orogeny was associated with significant crustal thickening, allowing exhumation of the granulite facies, Palaeoproterozoic, lower crust. Along-strike variations of the tectonic style suggest a larger amount of crustal shortening in the eastern part of the Alice Springs Orogeny.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1525-1314.2000.00289.x
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  • 3
    Electronic Resource
    Electronic Resource
    Erythema elevatum diutinum – evidence for disease-dependent leucocyte alterations and response to dapsone (2000)
    Oxford, UK : Blackwell Science Ltd
    British journal of dermatology 143 (2000), S. 0 
    Details
    ISSN: 1365-2133
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Erythema elevatum diutinum (EED) is a type of leucocytoclastic vasculitis of unknown aetiology. We report a patient with unusually widespread and disabling EED that had been unresponsive to corticosteroids and antibiotics, but resolved on dapsone. Biopsies of fresh lesions showed typical features of leucocytoclastic vasculitis, with prominent neutrophil infiltration, marked expression of the β2-integrins CR3 and LFA-1, and increased mast cell numbers. Older lesions exhibited granulation tissue and fibrosis, macrophages were more dominant, β2-integrins were expressed less markedly, and mast cell numbers were lower. In vitro chemotaxis of the patient’s peripheral blood neutrophils prior to treatment showed increased random migration and directed migration towards interleukin-8 (by 424%), but a profoundly decreased responsiveness towards the bacterial peptide analogue N-formyl-methionyl-leucyl-phenylalanine (fMLP) (by 98%). These values returned to normal after dapsone treatment and clinical improvement 5 months later. These findings support the concept that in EED, activation via cytokines such as interleukin-8 allows a selective recruitment of leucocytes to tissue sites, while immune complexes and bacterial peptides sustain the persistent local inflammatory infiltrate and the leucocytoclastic vasculitis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1046/j.1365-2133.2000.03673.x
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  • 4
    Electronic Resource
    Electronic Resource
    Validation of questions on asthma and wheeze in farming and anthroposophic children (2005)
    Oxford, UK : Blackwell Science Ltd
    Clinical & experimental allergy 35 (2005), S. 0 
    Details
    ISSN: 1365-2222
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Background In most epidemiological surveys the estimated prevalence of asthma is based on questionnaire responses, which may depend on the individual's perception as well as medical consulting habits in a given population. Therefore, measurement of bronchial hyper-responsiveness as a key feature of asthma has been suggested as an objective parameter for asthma.Objective The aim of the present study was to validate questionnaire responses on asthma and wheeze against bronchial response to hypertonic saline (HS) (4.5%) in populations previously shown to have a lower prevalence of asthma and allergies: farmers' children and children from anthroposophic families.Methods Children whose parents had completed a written questionnaire in the cross-sectional PARSIFAL-study were drawn from the following four subgroups: ‘farm children’ (n=183), ‘farm reference children’ (n=173), ‘Steiner schoolchildren’ (n=243) and ‘Steiner reference children’ (n=179). Overall, 319 children with wheeze in the last 12 months and 459 children without wheeze in the last 12 months performed an HS challenge.Results Odds ratios, sensitivity, specificity, likelihood ratios and measures of association did not differ significantly between the four subgroups. The correlation between the bronchial response to HS and wheeze and asthma questions was moderate and similar for farm children, farm reference children, Steiner schoolchildren and Steiner reference children (κ for ‘wheeze’: 0.25, 0.33, 0.31, 0.35, respectively, P=0.754, κ for ‘doctor's diagnosis of asthma’: 0.33, 0.19, 0.33, 032, respectively, P=0.499).Conclusion The findings from this study suggest that the reliabilitiy of questionnaire responses on asthma and wheeze is comparable between farmers' children, children raised in families with anthroposophic lifestyle and their respective peers.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1365-2222.2005.02308.x
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