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  • 1965-1969  (4)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Theory of computing systems 2 (1968), S. 127-145 
    ISSN: 1433-0490
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract “Meaning” may be assigned to a string in a context-free language by defining “attributes” of the symbols in a derivation tree for that string. The attributes can be defined by functions associated with each production in the grammar. This paper examines the implications of this process when some of the attributes are “synthesized”, i.e., defined solely in terms of attributes of thedescendants of the corresponding nonterminal symbol, while other attributes are “inherited”, i.e., defined in terms of attributes of theancestors of the nonterminal symbol. An algorithm is given which detects when such semantic rules could possibly lead to circular definition of some attributes. An example is given of a simple programming language defined with both inherited and synthesized attributes, and the method of definition is compared to other techniques for formal specification of semantics which have appeared in the literature.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Acta mathematica hungarica 20 (1969), S. 169-177 
    ISSN: 1588-2632
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-0878
    Keywords: Cell differentiation ; Spinal cord ; Cell cultures ; Trypsination
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Cervikales und thorakales Rückenmark 6 und 7 Tage alter Hühnerembryonen wurde trypsiniert. Die isolierten Rückenmarkszellen wurden kultiviert und anschließend licht- und elektronenmikroskopisch untersucht. Unmittelbar nach der Isolierung kann man die Zellen morphologisch nicht unterscheiden. Nach wenigen Stunden der Inkubation beobachtet man ein erstes Auswachsen feiner Portsätze. Nach ca. 12stündiger Kulturzeit beginnt eine Zusammenlagerung der Zellen in Zellklumpen und lockeren Zellverbänden immer deutlicher zu werden, ohne daß eine aktive Zellbewegung sichtbar wird. Die Zusammenlagerung der Zellen geht mit einer feinstrukturell verfolgbaren Ausreifung einher. Am Ende der 1. Woche findet man neben einigen astrocytären Gliazellen auch zahlreiche andere polymorphe Formen, die sich weder als Astroglia- noch als Oligodendroglia-Zellen typisieren lassen. Letztere konnten während der kurzen Inkubationsdauer weder licht- noch elektronenmikroskopisch identifiziert werden. Die Nervenzellen zeigen eine Zunahme ihrer Organellen und eine Zusammenlagerung ihres endoplasmatischen Retikulums zu Ergastoplasmaformationen. Axone und Dendriten sind bereits nach 3tägiger Inkubation erkennbar. Ein eindeutiges Kriterium der Nervenzellausreifung stellt die Bildung von Synapsen dar, die nach dem 5. Tag der Inkubation deutlich wird. Es bilden sich axo-dendritische, axosomatische und axo-axonale Synapsen. Die mögliche physiologische Bedeutung der Synapsen auf Grund ihrer Ultrastruktur und die Bedeutung der ‚'membrane junctions” wird diskutiert.
    Notes: Summary Cervical and thoracic segments of the spinal cord of six and seven days old chicken embryos were trypsinized. The isolated cells have been cultivated in vitro and studied both light- and electronmicroscopically. Immediately after isolation, neurons or glial cells can not be distinguished by morphological criteria. After a few hours in vitro, however, the first sprouting of fibres is visible. About 12 hours later an aggregation of cells in bulks or loosely woven nets becomes more and more prominent, without an active cellmovement visible. The aggregational process of the previously dissociated cells is combined with ultrastructural differentiation. At the end of the first week in vitro one could recognize besides some astrocytes a great number of those cells which were neither astroglia-nor oligodendroglia-cells. The latter were not detectable during our short periods of cultivation. Those cells showing an enhancement of organelles and their endoplasmic reticulum formed an ergastoplasm after five to seven days in vitro are definitely nerve cells, whose axons and dendrites appear after three days of incubation. The most convincing criteria of nerve cell maturation is the appearance of synapses, which increase in number from the fifth day of incubation onwards. Axo-dendritic, axo-somatic and axo-axonal synapses are present. A possible physiological significance of the synapses in relation to their ultrastructural features and the importance of the “membrane junctions” has been discussed.
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    BIT 5 (1965), S. 246-250 
    ISSN: 1572-9125
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract A completely equidistributed sequence of real numbers is constructed explicitly.
    Type of Medium: Electronic Resource
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