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  • 1980-1984  (6)
  • 1
    Electronic Resource
    Electronic Resource
    K, U and Th in mid-ocean ridge basalt glasses and heat production, K/U and K/Rb in the mantle (1983)
    [s.l.] : Nature Publishing Group
    Nature 306 (1983), S. 431-436 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Analyses on fresh glass samples of mid-ocean ridge basalt yield a uniform ratio K/U = 12,700 ± 200. In contrast, Th/U increases systematically with Th concentration. From these results we calculate an upper limit (1.5 pW kg−1) and a best estimate (0.6 pW ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/306431a0
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Sr and Nd isotope geochemistry of oceanic basalts and mantle evolution (1982)
    [s.l.] : Nature Publishing Group
    Nature 296 (1982), S. 821-825 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Sr and Nd isotope ratios are reported for 17 mid-ocean ridge basalts and for 11 oceanic islands and island groups. Data from the Azores, Samoa and the Society Islands diverge significantly from the mantle array. These results are not explained by binary mixing of depleted and undepleted mantle ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/296821a0
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Case studies on the origin of basalt (1983)
    Springer
    Contributions to mineralogy and petrology 84 (1983), S. 382-389 
    Details
    ISSN: 1432-0967
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract This paper presents a method for the systematic trace element modelling of a cogenetic suite of lavas. It is based on the geochemical inversion technique of Allègre and coworkers and utilizes the variations in the trace element concentrations of the lavas to calculate initial concentrations and source mineralogy. We reduce this inversion to a simple, step-by-step procedure: (1) correcting for fractional crystallization; (2) testing the inferred primary melt compositions for consistency with a model of equilibrium partial melts (with constant partition coefficients) formed from identical sources; (3) estimating the proportions of mineral phases entering the melt; (4) computing concentrations and bulk partition coefficients in the initial source relative to the concentration of a common reference element; (5) estimating relative mineral abundances in the source. Except for the fractionation correction, the calculations are done element by element using a direct analytic solution. For the purpose of comparison we apply this method to the same set of data used by Minster and Allègre (1978), a suite of lavas from Grenada (lesser Antilles) originally analyzed by Shimizu and Arculus (1975). The results of both methods agree well for the source abundances of the light REE, whereas the heavy REE abundances are shown to be poorly constrained by the data. Both methods require residual clinopyroxene and garnet in the source, but the ratio of these minerals is not well constrained. We are unable to reproduce the shape of D0 pattern (=bulk partition coefficients of the initial source) given by Minster and Allègre. The reason for this cannot be evaluated without repeating their calculations in detail. The set of data from Grenada is useful for comparison of the methods only, because it is now known from isotopic data that the samples are not truly cogenetic. Possibly better suited sets of samples for petrogenetic modelling are presented in parts II and III of this series.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01160289
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  • 4
    Electronic Resource
    Electronic Resource
    Availability of nitrogen and phosphorus in the nival zone of the Alps (1983)
    Springer
    Oecologia 57 (1983), S. 266-269 
    Details
    ISSN: 1432-1939
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary In high-alpine soils the maximum temperature is low even during the growing season, and hence mineralisation of nutrients is reduced. The aim of this study was to investigate what sources of nitrogen and phosphorus are available for vascular plants in the alpine nival zone to support growth. Using acetylene reduction assays levels of nitrogenase activity were assessed in sealed pots containing nival zone soil and plants at an altitude above 3000 m, and in bacterial isolates of soil and rhizosphere in the laboratory. Nitrogenase activity could not be detected in bacterial isolates or in the soil containing no plants. Small quantities of ethylen (〈87 nmol·h-1 per pot) were detected in pots with Cerastium uniflorum and Poa laxa. This activity must be attributable to rhizosphere bacteria since no evidence for the presence of cyanobacteria could be obtained. Other sources of nitrogen for the plants were detected in the form of ammonium and nitrate in soil water and in snow melt water. These solutions also contained extractable phosphorus in quantities normally considered to be sufficient for growth. Analyses of the internal concentration of nitrogen and phosphorus also suggested that these elements were present in adequate amounts in these plants. It was considered that soil and snow melt water together may provide sufficient nitrogen and phosphorus to support the extremely small annual growth increment of nival zone plants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00379589
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  • 5
    Electronic Resource
    Electronic Resource
    Differing effects of ursodeoxycholic or chenodeoxycholic acid on biliary cholesterol saturation and bile acid metabolism in man (1982)
    Springer
    Digestive diseases and sciences 27 (1982), S. 161-168 
    Details
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract A dose-response study comparing ursodeoxycholic and chenodeoxycholic acid was carried out in six men with asymptomatic radiolucent gallstones present in well-visualizing gallbladders. The study tested the effects of a low (averaging 6 mg/kg/day) or medium dose (averaging 11 mg/kg/day) of each bile acid on the cholesterol saturation of bile as well as on bile acid metabolism, as inferred from biliary and fecal bile acid composition. Ursodeoxycholic acid, at low or medium doses, induced bile desaturation in most patients, whereas chenodeoxycholic acid did not. Despite the greater desaturation efficacy of ursodeoxycholic acid, biliary bile acids became less enriched with the administered bile acid during ursodeoxycholic acid treatment than during chenodeoxycholic acid treatment. Both bile acids were nearly completely 7-dehydroxylated to lithocholic acid by colonic bacteria, but biliary lithocholic increased only slightly (and similarly) with each bile acid. Fecal bile acid composition suggested that administered ursodeoxycholic acid suppressed endogenous bile acid synthesis much less than chenodeoxycholic acid. The results indicate that ursodeoxycholic acid and chenodeoxycholic acid have similar but not identical effects on bile acid metabolism, but that for a given dose, ursodeoxycholic acid is a more potent desaturating agent than chenodeoxycholic acid. The results suggest that cholesterol gallstone dissolution with ursodeoxycholic acid should occur with a dose of 8–10 mg/kg in most nonobese patients.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01311711
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  • 6
    Electronic Resource
    Electronic Resource
    Clinical experience with monooctanoin for dissolution of bile duct stones (1981)
    Springer
    Digestive diseases and sciences 26 (1981), S. 954-955 
    Details
    ISSN: 1573-2568
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01309504
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