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  • 1
    ISSN: 1573-8868
    Keywords: Bayesian inference ; extinction time ; survival analysis ; incompleteness of the fossil record
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Mathematics
    Notes: Abstract Stratigraphic sections are often sampled at well-defined discrete points. Because of the incompleteness of the fossil record, a particular species may not be observed even when it is extant at a sampling point. We introduce a model and Bayesian analysis for estimating the true time of disappearance of a lineage from a section in the face of the possibility that failure to find the species beyond its observed stratigraphic range may represent false negatives. We incorporate proper prior information, including an estimated longevity of the species and the probability that it will be observed if extant. Our analysis produces a posterior density for the true extinction time of the species. Summaries of this probability distribution provide a point estimate of the extinction time, a standard deviation for the uncertainty in the estimate, and confidence intervals for the time of extinction. We apply our model to stratigraphic ranges of benthic foraminifera collected from the early Late Cretaceous (Cenomanian and Turonian) from Eastbourne, England.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 1911-1925 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Carboxy-terminated polybutadiene neutralized with Cu2+ (CuPBD) and its blend with poly(styrene-co-4-vinylpyridine) (SVP) were examined by differential scanning calorimetry (DSC), transmission electron microscopy (TEM), small-angle x-ray scattering (SAXS), and extended x-ray absorption fine structure (EXAFS) spectroscopy. The DSC results indicate that in the blend substantial mixing occurs in the CuPBD-rich phase, although complete miscibility is not achieved, and the SVP-rich phase remains relatively pure. The TEM micrographs indicate that the morphology, while irregular, is reasonably described as bicontinuous, with a domain size of order 100 nm. The SAXS patterns show that the ionic aggregates present in CuPBD are destroyed upon blending, which is interpreted as being due to steric hindrances between ionic groups coordinated to vinylpyridine nitrogens. The EXAFS radial structure function of the blend exhibits a marked decrease in the Cu-Cu peak in comparison with CuPBD, indicating a change in local structure upon blending. The results indicate that some of the SVP is miscible with CuPBD owing to complexation between the pendant pyridine groups and the Cu2+ ions, which disrupts the ionic aggregates. However, the two materials are not fully miscible, leading to a rather coarse two-phase morphology.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 26 (1988), S. 1545-1548 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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