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  • Ontogeny  (2)
  • incompressible flow  (2)
  • 14.80.Am  (1)
  • 34.50  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 167 (1990), S. 757-769 
    ISSN: 1432-1351
    Keywords: Ontogeny ; Auditory fovea ; Tonotopy ; Sexual dimorphism ; Rhinolophus rouxi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary This report describes the ontogenesis of tonotopy in the inferior colliculus (IC) of the rufous horseshoe bat (Rhinolophus rouxi). Horseshoe bats are deaf at birth, but consistent tonotopy with a low-to-high frequency gradient from dorsolateral to ventromedial develops from the 2nd up to the 5th week. The representation of the auditory fovea is established in ventro-mediocaudal parts of the IC during the 3rd postnatal week (Fig. 3). Then, a narrow frequency band 5 kHz in width, comprising 16% of the bat's auditory range, captures 50–60 vol% of the IC (Fig. 3c). However, foveal tuning is 10–12 kHz (1/3 octave) lower than in adults; foveal tuning in females (65–68 kHz) is 2–3 kHz higher than in males (62–65 kHz). Thereafter, foveal tuning increases by 1–1.5 kHz per day up to the 5th postnatal week, when the adult hearing range is established (Figs. 4, 5). The increase of sensitivity and of tuning sharpness of single units also follows a low-to-high frequency gradient (Fig. 6). Throughout this development the foveal tuning matches the second harmonic of the echolocation pulses vocalised by these young bats. The results confirm the hypothesis of developmental shifts in the frequency-place code for the foveal high frequency representation in the IC.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Journal of comparative physiology 167 (1990), S. 771-784 
    ISSN: 1432-1351
    Keywords: Ontogeny ; Audition ; Vocalisation ; Sensorimotor interaction ; Rhinolophus rouxi
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary Horseshoe bats (Rhinolophus rouxi) were deafened in their 3rd–5th postnatal week. Subsequently their vocalisations were monitored to evaluate the impact of audition on the development of echolocation pulses. Hearing impairment affected the echolocation pulses as follows: the frequency of the constant frequency (CF) component was altered by between + 4 kHz and − 14 kHz, and the dominance of the second harmonic of the pulses was neutralised by a relative increase in intensity of the first and third harmonics. A second experiment focused on possible influences of acoustical self-stimulation with echolocation pulses on the establishment of auditory fovea representation in the inferior colliculus (IC). Frequency control of echolocation pulses was disrupted by larynx denervation. Thereafter, the bats produced multiharmonic echolocation signals (4–11 harmonics) varying in frequency. IC tonotopy, however, as monitored by stereotaxic electrophysiology, showed the same developmental dynamics as seen in control specimens (Fig. 10). Both experiments indicate that throughout postnatal development echolocation pulses are under auditory feedback control, whereas maturation of the auditory fovea and shifts in its frequency tuning represent an innate process. The significance of this postnatal development might be the adjustment of the vocal motor system of each bat to the frequency of its ‘personal’ auditory fovea.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    The European physical journal 339 (1991), S. 391-398 
    ISSN: 1434-601X
    Keywords: 14.80.Am ; 25.20.Gf ; 25.20.Lj
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We calculate the differential cross section for nucleonnucleon bremsstrahlung in covariant way based on a realistic meson-exchange approximation for the NN-scattering amplitude. The results are discussed in comparison to semiclassical approximations and with respect to the role of internal radiation diagrams. The influence of the anomalous magnetic moment on the proton-neutron bremsstrahlung is found to contribute up to 50% for specific kinematical conditions. Recent measurements on the elementary differential cross sectionpn→pnγ are found to be quite accurately reproduced. Furthermore, for use in proton-nucleus and nucleus-nucleus collisions, we present a parametrization of thepnγ cross section within a broad kinematical range.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-0649
    Keywords: 42.60 ; 34.50
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Saturation of two-dimensional laser-induced fluorescence is demonstrated using the coincidence between the strong 0–0 vibrational transition of OH around 308 nm and the emission of a tunable XeCl excimer laser. The 2D images were insensitive to variations in the laser power, implying reduced sensitivity to quenching processes. The ratio of the 2D images in the linear and saturated regimes show two-dimensional variations in the saturation intensity. Since saturation intensity is proportional to the quenching rate, this novel method allows one to check for variations in collisional lifetimes across the flame.
    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 42 (1998), S. 175-189 
    ISSN: 0029-5981
    Keywords: incompressible flow ; rotor-stator configurations ; multigrid methods ; parallel computing ; moving grids ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A parallel multigrid finite volume solver for the prediction of unsteady flows in rotor-stator configurations using a moving-grid technique is presented. The numerical solution procedure is based on a second-order finite volume discretization with collocated block-structured grids, an implicit time discretization, a pressure-correction procedure of SIMPLE type, a non-linear multigrid method and a grid partitioning technique for parallelization. For the handling of the rotation and the relative movement of stationary and moving parts of the configuration a splitting technique is employed, which, based on the block structuring, divides the computational domain in a stationary and a rotating part. According to this splitting, the time-dependent flow equations are solved in a stationary and rotating frame of reference, and a special coupling procedure is used for the interfacial blocks. The method is investigated with respect to its accuracy, where special emphasis is given to the influence of different interpolation techniques of pressure-related terms within the non-staggered pressure-correction scheme. As a practical application, the flow in a stirrer configuration with baffles is studied, for which also results concerning the numerical and parallel efficiency of the proposed method are given. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 22 (1996), S. 549-565 
    ISSN: 0271-2091
    Keywords: parallel computing ; multigrid method ; finite volume method ; block-structured grids ; incompressible flow ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: In this paper a parallel multigrid finite volume solver for the prediction of steady and unsteady flows in complex geometries is presented. For the handling of the complexity of the geometry and for the parallelization a unified approach connected with the concept of block-structured grids is employed. The parallel implementation is based on grid partitioning with automatic load balancing and follows the message-passing concept, ensuring a high degree of portability. A high numerical efficiency is obtained by a non-linear multigrid method with a pressure correction scheme as smoother.By a number of numerical experiments on various parallel computers the method is investigated with respect to its numerical and parallel efficiency. The results illustrate that the high performance of the underlying sequential multigrid algorithm can largely be retained in the parallel implementation and that the proposed method is well suited for solving complex flow problems on parallel computers with high efficiency.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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