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  • 1
    Electronic Resource
    Electronic Resource
    Optimal harvesting-coefficient control of steady-state prey-predator diffusive Volterra-Lotka systems (1995)
    Springer
    Applied mathematics & optimization 31 (1995), S. 219-241 
    Details
    ISSN: 1432-0606
    Keywords: Elliptic systems ; Optimal harvest ; Prey-predator ; 49K20 ; 90A30 ; 35J60 ; 92D40 ; 49M99
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract This article considers the optimal control of the harvesting of a prey-predator system in an environment. The species are assumed to be in steady state under diffusion and Voterra-Lotka type of interaction. They are harvested for economic profit, leading to reduction of growth rates; and the problem is to control the spatial distributions of harvests so as to optimize the return. Precise conditions are found so that the optimal control can be rigorously characterized as the solution of an optimality system of nonlinear elliptic partial differential equations. Moreover, a constructive approximation scheme for optimal control is given.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01182789
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  • 2
    Electronic Resource
    Electronic Resource
    Optimal Control of Multigroup Neutron Fission Systems (1999)
    Springer
    Applied mathematics & optimization 40 (1999), S. 39-60 
    Details
    ISSN: 1432-0606
    Keywords: Key words. Parabolic systems, Optimal control, Neutron fission, Reactiondiffusion. AMS Classification. Primary 49K20, 82D75, 35K57, 49M99, Secondary 81V35.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Abstract. This article considers the optimal control of nuclear fission reactors modeled by parabolic partial differential equations. The neutrons are divided into fast and thermal groups with two equations describing their interaction and fission, while a third equation describes the temperature in the reactor. The coefficient for the fission and absorption of the thermal neutron is assumed to be controlled by a function through the use of control rods in the reactor. The object is to maintain a target neutron flux shape, while a desired power level and adjustment costs are taken into consideration. A nonlinear optimality system of six equations is deduced, characterizing the optimal control. An iterative procedure is shown to contract toward the solution of the optimality system in small time intervals. The theory is extended to include the effect of other fission products, leading to coupled ordinary and partial differential equations. Numerical experiments are also included, suggesting directions for further research.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002459900115
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  • 3
    Electronic Resource
    Electronic Resource
    Complementation analysis in Gaucher disease using single cell microassay techniques. Evidence for a single “Gaucher gene” (1983)
    Springer
    Human genetics 〈Berlin〉 65 (1983), S. 112-116 
    Details
    ISSN: 1432-1203
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Gaucher disease is a lysosomal storage disorder resulting from a deficiency of acid β-glucosidase. Several clinical forms have been described, including infantile, juvenile, and adult onset variants. We have examined complementation in infantile and adult forms of Gaucher disease by monitoring enzyme activity in multinucleate cells produced by fusing skin fibroblasts from different patients in the presence of polyethylene glycol. β-Glucosidase activity was monitored in lysates of individual multinucleate cells by a microassay method utilizing methylumbelliferyl-β-D-glucoside as the substrate (normal: 1.3±0.12x10-13 mol/h/cell). The microassay was linear with time up to 4 h, for up to 20 mononucleate cells, and for individual multinucleate cells containing up to 12 nuclei. Complementation was examined in 11 fibroblasts strains fused in all pairwise combinations. In no instance was there any clear indication of complementation (at least 10–15% of normal activity to adequately account for experimental variation) although there was an indication of marginal increases in some fusions. On the other hand, the expected 50% activity was obtained in “heterozygous” fusions (normal/mutant) for both types of clinical variants. Our results are consistent with a single gene, presumably the structural gene encoding the enzyme, responsible for at least the infantile and adult variants, and confirm the autosomal recessive nature of the disorder.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00286645
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  • 4
    Electronic Resource
    Electronic Resource
    Nonlinear natural vibration analysis of beams by selective coefficient increment (1989)
    Springer
    Computational mechanics 5 (1989), S. 73-80 
    Details
    ISSN: 1432-0924
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The amplitude-frequency relation (backbone curve) of an elastic body in large amplitude natural vibration at resonance (including internal resonance) is of interest. The backbone curve is constructed by amplitude increment (decrement). Since the amplitude is given as a combination of harmonic components, the increment is performed actually on the coefficients of the harmonic components. An assumed increment is first applied to the first harmonic coefficient (the active harmonic) and a new equilibrium state is found by the Newtonian algorithm. The frequency increment is computed, all the harmonic coefficients are adjusted and the amplitude is evaluated. During the process, it is possible that one of the originally small harmonic coefficients suddenly increases in magnitude. The harmonic coefficient is selected to be the new active harmonic in the next step to find a new equilibrium state. The internal resonance of order 5 combining the first and the third linear modes of a clamped-clamped beam is predicted without difficulty. Therefore, automatic computation of combined resonance is straight forward. Matrix notation is used when possible to given concise presentation. The method is readily applicable in finite element sense.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01046880
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  • 5
    Electronic Resource
    Electronic Resource
    Decrease in light diffraction intensity of contracting muscle fibres (1988)
    Springer
    European biophysics journal 15 (1988), S. 359-368 
    Details
    ISSN: 1432-1017
    Keywords: Light diffraction intensity ; muscle fibres
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Single fibres from the semitendinosus muscle of frog were illuminated normally with a He−Ne laser. The intensity transient and fine structure pattern of light diffracted from the fibre undergoing isometric twitches were measured. During fibre shortening, the intensity decreased rapidly and the fine structure pattern preserved its shape and moved swiftly away from the undiffracted laser beam. The fine structure patterns of the contracting and resting fibre were nearly identical. The ratio of intensities of the contracting and resting fibre of the same sarcomere length was determined as a function of the time elapsed after fibre stimulation. The time-resolved intensity ratio increased with sarcomere length and became unity when sarcomere length was between 3.5 μm and 3.7 μm. A diffraction theory based on the sarcomere unit was developed. It contained a parameter describing the strength of filament interaction. The comparison between the theory and data shows that the initial intensity drop during contraction is primarily due to filament interactions. At a later stage of contraction, sarcomere disorder becomes the major component causing the intensity to decrease. Diffraction models which use the Debye-Waller formalism to explain the intensity decrease are discussed. The sarcomere-unit diffraction model is applied to previously reported intensity measurements from active fibres.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254723
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  • 6
    Electronic Resource
    Electronic Resource
    Ergodic families of affine operators (1975)
    Springer
    Mathematische Annalen 216 (1975), S. 273-284 
    Details
    ISSN: 1432-1807
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01430968
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  • 7
    Electronic Resource
    Electronic Resource
    Low-rate dynamic contact angles on poly(n-butyl methacrylate) and the determination of solid surface tensions (1998)
    Springer
    Colloid & polymer science 276 (1998), S. 459-469 
    Details
    ISSN: 1435-1536
    Keywords: Key words Poly(n-butyl methacrylate)-polymer ; contact angle ; surface tension
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract  Low-rate dynamic contact angles of 22 liquids on a poly(n-butyl methacrylate) (PnBMA) polymer are measured by an automated axisymmetric drop shape analysis-profile (ADSA-P). It is found that 16 liquids yielded non-constant contact angles, and/or dissolved the polymer on contact. From the experimental contact angles of the remaining 6 liquids, it is found that the liquid–vapor surface tension times cosine of the contact angle changes smoothly with the liquid–vapor surface tension, i.e. γlv cos θ depends only on γlv for a given solid surface (or solid surface tension). This contact angle pattern is in harmony with those from other inert and non-inert (polar and non-polar) surfaces [34–37, 45–47]. The solid–vapor surface tension calculated from the equation-of-state approach for solid-liquid interfacial tensions [14] is found to be 28.8 mJ/m2, with a 95% confidence limit of ±0.5 mJ/m2, from the experimental contact angles of the 6 liquids.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s003960050267
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  • 8
    Electronic Resource
    Electronic Resource
    Sarcomere dynamics in single myocardial cells as revealed by high-resolution light diffractometry (1983)
    Springer
    Journal of muscle research and cell motility 4 (1983), S. 485-502 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary A specially designed diffractometer with a high spatial and temporal resolution recorded the diffraction of a laser beam by single enzymatically isolated myocardial cells. The fine structures within the first-order diffraction were resolved and each structure was interpreted as the diffraction from a group of sarcomeres of nearly equal length. During activation of the cell dynamics of each discrete group of sarcomeres was uniform and independent of the other groups. However, a small nonuniform component in the sarcomere dynamics was observed and attributed to the coupling between the shortening tension and the radial stress resulting from the expansion of the myofibrillar cross-section. The time-course of the diffraction fine structures during contractile activity revealed (1) the period of the contraction-relaxation cycle, (2) the latent period, (3) the shortening and relengthening speeds and (4) the variation in the line width and intensity of the fine structure. Measurements showed that the latent period was dependent on the free Ca2+ of the cell's bathing solution while the initial shortening speed was not. The diffraction line width and intensity of the shortening cell were explained by the grating model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00711951
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  • 9
    Electronic Resource
    Electronic Resource
    Light diffraction by striated muscle fibres in the transverse direction (1983)
    Springer
    Journal of muscle research and cell motility 4 (1983), S. 557-568 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The intensity of the diffraction line, the transverse intensity, of a single skeletal muscle fibre illuminated at normal incidence with a laser beam decayed monotonically to zero at both ends of the diffraction line. This characteristic decay was observed for most illuminated spots of the fibre. However, for a few spots the transverse intensity showed distinctive oscillations. The intensity distribution of the diffraction line is explained by a diffraction model in which the muscle fibre acts as a bundle of randomly packed myofibrils of different diameters. The equatorial intensity was calculated as a function of myofibrillar diameter dispersion. The comparison between the theoretical curves and measurements yields an estimation for the myofibrillar diameter dispersion. The calculations predict that the transverse intensity would exhibit oscillations when the diameter dispersion is less than 22%. Finally, the diameter dispersions estimated by light diffractometry and electron microscopy are compared.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712115
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  • 10
    Electronic Resource
    Electronic Resource
    Laser diffraction of single intact cardiac muscle cells at rest (1982)
    Springer
    Journal of muscle research and cell motility 3 (1982), S. 399-418 
    Details
    ISSN: 1573-2657
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The laser diffraction of single cardiac muscle cells shows distinctive diffraction orders and has the following characteristics. (1) When projected on a screen each diffraction order can be described as an irregular column of fine structures consisting of elliptical spots and short jagged stripes. (2) The fine structures associated with the left and right diffractions of the same diffraction order cannot be correlated according to the plane grating equation, and they do not interchange after the cell has been rotated by 180° around its length. (3) For the same diffraction order, the average diffraction angle of the fine structures as a function of laser incident angle follows the plane grating equation. (4) The meridional diffraction angles of different orders are not related by the plane grating equation. (5) For the same diffraction order, the total intensities of the left and right diffractions are not equal. (6) The left or right intensity of a diffraction column shows a single broad peak as a function of laser incident angle. The incident angles corresponding to the left and right peaks are symmetrical to the axis of normal incidence and are interpreted as the Bragg angles of the Z-discs and the planes formed by the intersections of the A- and I-bands of individual myofibrils. The diffraction measurements are consistent with a model in which the myofibrils are randomly packed in the cell and each myofibril acts as a cylindrical diffractor of one-dimensional order.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00712091
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