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  • 1
    Electronic Resource
    Electronic Resource
    Engineered Schottky barrier diodes for the modification and control of Schottky barrier heights (1987)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 61 (1987), S. 5159-5169 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A technique for fabricating controlled Schottky barrier heights to GaAs over the entire band gap is demonstrated. Thin, highly doped semiconductor layers at the metal-semiconductor interface allowed the reproducible control of the effective barrier height on n-type GaAs from near zero (i.e., ohmic behavior at 300 K) to 1.33 eV (the band gap equals 1.43 eV at 300 K) with diode ideality factors 1.02≤n≤1.21. Molecular-beam epitaxy was used to grow GaAs epitaxial layers with in situ deposited Al metal layers, resulting in diodes with nearly ideal electrical and structural characteristics. Electrical characterization by current-voltage (I-V) and capacitance-voltage (C-V) techniques, models for these I-V and C-V characteristics, and structural characterization by high resolution transmission electron microscopy lattice images are presented. Implications of this work for models of Schottky barrier formation are discussed, as well as some applications for these "engineered Schottky barrier diodes.''
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.338290
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Von HippelLindau disease maps to the region of chromosome 3 associated with renal cell carcinoma (1988)
    [s.l.] : Nature Publishing Group
    Nature 332 (1988), S. 268-269 
    Details
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The primary biochemical defect in VHL is not yet known. We have therefore used genetic-linkage analysis with polymorphic DNA markers as a first step in applying chromosome-specific cloning techniques to the isolation and characterization of the defect. As VHL is associated with inherited ...
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1038/332268a0
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The decline of the Serengeti Thomson's gazelle population (1987)
    Springer
    Oecologia 73 (1987), S. 32-40 
    Details
    ISSN: 1432-1939
    Keywords: Thomson's gazelles ; Serengeti population decline ; Predation ; Interspecific competition ; Disease
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The population of Thomson's gazelles in the Serengeti National Park, Tanzania has declined by almost two thirds over a 13 year period. In the early 1970s, numbers stood at 0.66 million animals but had decreased to less than 0.25 million animals in 1985 as estimated by 5 different censuses using two different counting techniques. Predation, interspecific competition and disease are all factors that could have contributed to this decline, and at least one of these factors, predation, could now prevent the Thomson's gazelle population from increasing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00376974
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Chimpanzees' (Pan troglodytes) choice of prey among termites (macrotermitinae) in western Tanzania (1985)
    Springer
    Primates 26 (1985), S. 375-389 
    Details
    ISSN: 0032-8332
    Keywords: Chimpanzee ; Pan troglodytes ; Diet ; Prey choice ; Termite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract This study examines factors affecting chimpanzees' preying on termites, especially their choice of prey species. Regular surveys of a large sample of termite-mounds in the Mahale Mountains, Tanzania, confirmed that chimpanzees of B Group obtainedMacrotermes, which were relatively uncommon, by the use of fishing-tools, but ignored the much more abundantOdontotermes. This preference appeared to reflectMacrotermes' more extended swarming period, greater accessibility, larger size, and less noxious taste than the soldiers ofOdontotermes. Similar factors probably underly the chimpanzees' choice ofMacrotermes at Gombe, butPseudacanthotermes spiniger are also common there, and their absence from the diet is less easily explained. In contrast, the chimpanzees of K Group at Mahale prey mainly onP. spiniger;Macrotermes are apparently absent, andP. spiniger appear to be more abundant, accessible, and palatable than the alternativeOdontotermes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02382454
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  • 5
    Electronic Resource
    Electronic Resource
    Termite fauna related to differences in tool-use between groups of chimpanzees (Pan troglodytes) (1987)
    Springer
    Primates 28 (1987), S. 457-471 
    Details
    ISSN: 0032-8332
    Keywords: Chimpanzees ; Termites ; Tool-use ; Culture ; Mahale ; Gombe
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Nishida andUehara have contrasted two groups of chimpanzees at the Mahale Mountains in their manner of obtaining termites for food. K-group very rarely used tools, but evidence suggested that B-group did so regularly to fish forMacrotermes. They suggested that this difference was not a cultural one, but was explained by the absence ofMacrotermes in K-group's range. We attempted to test this hypothesis, and here examine the termite fauna in the ranges of the two groups. Our data confirm that termite-fishing was contingent upon the presence ofMacrotermes in B-group's range, and that cultural explanations are not necessary to explain the rarity of tool use by K-group, which instead could catchPseudacanthotermes without using tools. Comparison of the termite faunas in the ranges of K-group, of B-group, and of the chimpanzees at Gombe, suggest that, apart fromMacrotermes, two genera might be the main alternative prey:Pseudacanthotermes, which could be more commonly included in the diet at Gombe, and might also be eaten by B-group, andCubitermes which is available at both these sites.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02380861
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  • 6
    Electronic Resource
    Electronic Resource
    Optimum specimen positioning in the electron microscope using a double-tilt stage (1989)
    New York, NY : Wiley-Blackwell
    Journal of Electron Microscopy Technique 11 (1989), S. 33-40 
    Details
    ISSN: 0741-0581
    Keywords: High-voltage electron microscopy ; Thick specimens ; Tomography ; Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Natural Sciences in General
    Notes: Optimal imaging of complex structures requires proper alignment relative to the optic axis of the electron microscope. This is especially important for high-voltage and intermediatevoltage microscopes, which form an in-focus image throughout the entire thickness of the object. As a result, structures at different specimen heights form overlapping and confused images that severely curtail the usefulness of these instruments.The work described here provides a generalized, flexible method for optimizing specimen orientation and eliminating or limiting image overlap by means of a commonly used double-tilt stage. Analysis of the motion about the two axes provides accurate tilting for any azimuthal direction whether or not it corresponds to a mechanical axis of the stage. An object can be positioned to minimize image overlap, to record stereopairs for any parallax axis, and to record three-dimensional data sets by the conical collection geometry.Images of muscle paracrystals are shown after tilting about an axis perpendicular to a symmetry direction. The tilted image displays higher-order symmetry, which is altered by changes of one degree. Precision double-tilting for optimizing stereopairs is shown for a desmosome recorded using different parallax axes and pretilts. A tomographic conical data-collection scheme is demonstrated by imaging a microtubule axoneme for a specific cone half-angle and arbitrary azimuthal angles.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jemt.1060110106
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