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  • 1
    Electronic Resource
    Electronic Resource
    The effect of cytochalasin B on the rate of growth and ultrastructure of wheat coleoptiles and maize roots (1979)
    Springer
    Planta 144 (1979), S. 373-383 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF00391581
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  • 2
    Electronic Resource
    Electronic Resource
    Laser phase and frequency stabilization using an optical resonator (1983)
    Springer
    Applied physics 31 (1983), S. 97-105 
    Details
    ISSN: 1432-0649
    Keywords: 06 ; 07.60 ; 07.65
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe a new and highly effective optical frequency discriminator and laser stabilization system based on signals reflected from a stable Fabry-Perot reference interferometer. High sensitivity for detection of resonance information is achieved by optical heterodyne detection with sidebands produced by rf phase modulation. Physical, optical, and electronic aspects of this discriminator/laser frequency stabilization system are considered in detail. We show that a high-speed domain exists in which the system responds to the phase (rather than frequency) change of the laser; thus with suitable design the servo loop bandwidth is not limited by the cavity response time. We report diagnostic experiments in which a dye laser and gas laser were independently locked to one stable cavity. Because of the precautions employed, the observed sub-100 Hz beat line width shows that the lasers were this stable. Applications of this system of laser stabilization include precision laser spectroscopy and interferometric gravity-wave detectors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00702605
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Dye-laser frequency stabilization using optical resonators (1984)
    Springer
    Applied physics 33 (1984), S. 179-185 
    Details
    ISSN: 1432-0649
    Keywords: 06 ; 07.60 ; 42.60
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We describe a study, performed using heterodyne techniques, of the frequency fluctuations of two completely independent ring dye lasers locked to independent reference cavities. Single laser linewidths of less than 750 Hz were achieved, the principal limitation being residual vibrations from the noisy laboratory environment. With future design and environmental improvements, ultranarrow linewidths are expected thus providing a useful tool for a great variety of high precision experiments.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00688526
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  • 4
    Electronic Resource
    Electronic Resource
    A quantitative stereological analysis of the effect of indoleacetic acid on the dictyosomes in pea stem epidermal cells (1985)
    Springer
    Protoplasma 125 (1985), S. 230-234 
    Details
    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
    URL: http://dx.doi.org/10.1007/BF01281242
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  • 5
    Electronic Resource
    Electronic Resource
    The multigrid method in solid mechanics: Part II - Practical applications (1990)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 29 (1990), S. 739-753 
    Details
    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
    URL: http://dx.doi.org/10.1002/nme.1620290405
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  • 6
    Electronic Resource
    Electronic Resource
    The multigrid method in solid mechanics: Part I - Algorithm description and behaviour (1990)
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 29 (1990), S. 719-737 
    Details
    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
    URL: http://dx.doi.org/10.1002/nme.1620290404
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    Paper (German National Licenses)
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