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  • ATPase cytochemistry  (2)
  • Dictyosomes  (2)
  • Engineering General  (2)
  • 1
    ISSN: 1432-2048
    Keywords: Auxin ; Cell elongation ; Cytochalasin B ; Dictyosomes ; Secretion ; Triticum ; Zea
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Cytochalasin B (CB) inhibits the elongation growth of maize roots, and that of wheat coleoptile segments incubated in indolyl-3-acetic acid, by over 30% after a lag period of about 60 min. This long lag is not due to poor tissue penetration by the inhibitor, but seems to reflect a property of the process inhibited by CB. The only visible ultrastructural change accompanying growth inhibition is the accumulation of secretory vesicles in the vicinity of dictyosomes, which occurs between 90 and 300 min. However, a massive accumulation of vesicles is seen after 120 min in root cap cells which possess very active dictyosomes. The results indicate that CB does not inhibit elongation growth by interfering with cytoplasmic streaming. Instead, they indicate that the drug acts to inhibit the secretion of cell wall components at some stage after vesicle production, but prior to their transport.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1615-6102
    Keywords: Dictyosomes ; Indoleacetic acid ; Pisum sativum ; Stereology
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary A quantitative analysis of electron micrographs showed that IAA treatment caused an initial rapid increase in the amount of dictyosome material in pea stem epidermal cells. The increase was detected within 15 minutes of auxin presentation and reached a maximum around 30 minutes. This was followed by a decrease, presumably due to an increased utilization of the organelle. The decrease involved a fall in the amount of dictyosome-derived vesicles and in the actual number of dictyosomes. The results are discussed in relation to similar observations on expanding cells of monocotyledonous plants.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Protoplasma 104 (1980), S. 55-65 
    ISSN: 1615-6102
    Keywords: ATPase cytochemistry ; Phloem ; Ricinus communis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Standard lead precipitation procedures have been used to examine the localization of ATPase activity in phloem tissues ofRicinus communis. Reaction product was localized on the plasma membrane of the companion cells associated with sieve elements and of parenchyma cells in phloem tissues from the leaf, petiole, stem and root. ATPase activity was also present on the plasma membrane and dispersed P-protein of sieve elements in petiole, stem and root tissue, but was absent from the plasma membrane of these cells in the leaf minor veins. Substitution ofβ-glycerophosphate for ATP produced no change in the localization of reaction product in leaf tissue. These findings are discussed in relation to current theories on the mechanism of sugar transport and phloem loading.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1615-6102
    Keywords: Analytical electron microscopy ; ATPase cytochemistry ; Plasma membrane ; Ricinus communis ; Triticum aestivum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The claim that osmium-containing deposits which lack lead are frequently and incorrectly interpreted as enzymatic reaction products in lead precipitation techniques for ATPase localization in plants is without foundation. Proper controls clearly demonstrate the enzymatic origin of membrane-located deposits and the presence of lead is confirmed by analytical electron microscopy.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 29 (1990), S. 739-753 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: The performance of the multigrid algorithm is investigated by solving some large, practical, three dimensional solid mechanics problems. The convergence of the method is sensitive to factors such as the amount of bending present and the degree of mesh non-uniformity, as was also observed in Part I for two dimensional problems. However, in contrast to Part I, no proportionality is observed between the total number of operations to convergence and the problem size. Despite such behaviour, the multigrid algorithm proves to be an effective matrix equation solver for solid mechanics poblems. It is orders of magnitude faster than a direct factorization method, and yields converged solutions several times faster than the Jacobi preconditioned conjugate gradient method.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 29 (1990), S. 719-737 
    ISSN: 0029-5981
    Keywords: Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A multigrid algorithm is described that can be used to obtain the finite element solution of linear elastic solid mechanics problems. The method is applied to some two dimensional problems to evaluate its strengths and weaknesses. Extensive studies are made to determine the convergence behaviour of the method. In general, this depends on many factors: the number of degrees-of-freedom in the discretization, characteristics of the algorithm, Poisson's ratio when it is close to 0·5, the amount of bending deformation in the problem under consideration, and the degree of non-uniformity in the mesh. Only certain values of the multigrid parameters allow a converged solution to be obtained with a computational effort proportional to the number of degrees-of-freedom. These values include the optimum ones, i.e. those that lead to convergence with the least computational effort. The constant of proportionality is only independent of the number of degrees-of-freedom and still depends on the other factors listed above.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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