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  • 1
    Electronic Resource
    Electronic Resource
    The temporal effects of Dufour's gland secretion in host discrimination by Nemeritis canescens (1985)
    Springer
    Entomologia experimentalis et applicata 38 (1985), S. 215-220 
    Details
    ISSN: 1570-7458
    Keywords: Nemeritis canescens ; Hymenoptera ; Ichneumonidae ; Ephestia kuehniella ; Dufour's gland ; marker pheromone ; discrimination ; superparasitism
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé Des expériences sur le comportement de N. canescens ont montré que les sécrétions de la glande de Dufour sont utilisées comme phéromone de marquage pouvant affecter le comportement des autres hyménoptères face aux chenilles contaminées. Ce maqueur externe est produit à partir des sécrétions de la glande de Dufour, il a un effet dissuasif qui dure environ 32 heures après son émission. La séquence des actes comportementaux de Nemeritis montre un accroissement significatif de réactions de ‘fuite’ et d'‘évitement’ face à des chenilles d'Ephestia traitées superficiellement avec du contenu des glandes de Dufour. Cet article prouve pour la première fois que Nemeritis réagit aussi bien à des marqueurs externes qu'internes. Un comportement analogue vis à vis de papier filtre imprégné du contenu des glandes de Dufour et de son constituant hénéicosane constitue une preuve que le contenu de la glande influe sur le comportement de l'hymenoptère et ainsi lui évite de superparasiter ses hôtes.
    Notes: Abstract Behavioural experiments with Nemeritis canescens Grav. have demonstrated that the secretions from its Dufour's gland are used as a marker pheromone which can affect the behaviour of other wasps towards host caterpillars bearing it. The external marker is produced within the complex of secretions from the Dufour's gland and has oviposition deterrent effect which lasts approximately 32 h after deposition. The sequence of behaviour patterns shown by individual Nemeritis is described and shows a significant increase in ‘escape’ and ‘avoidance’ reactions towards Ephestia caterpillars treated topically with the Dufour's gland contents. This paper presents evidence for the first time to indicate that Nemeritis reacts to an external marker as well as to an internal one. Similar behaviour towards filter paper treated topically with contents of whole Dufour's gland and its component heneicosane contribute evidence for the conclusion that the gland contents influence the wasp's behaviour and hence its avoidance of superparasitism of its host.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295253
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    A quantitative method for thein vitro study of sounds produced by prosthetic aortic heart valves Part I: analytical considerations (1984)
    Springer
    Medical & biological engineering & computing 22 (1984), S. 32-39 
    Details
    ISSN: 1741-0444
    Keywords: Fast Fourier transform ; Noninvasive diagnosis ; Prosthetic heart valve ; Sound
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A method is presented for analysing sounds producedin vitro by prosthetic aortic heart valves, and a one-dimensional harmonic model is described. Procedures for estimating physical parameters of the model are outlined for the case of transient and nontransient sounds, and a computational method is described for making comparisons between two general sounds. The fast Fourier transform provides a satisfactory means for the basic transformation to the frequency domain. Useful representations of the acoustical information that are considered are the original time and amplitude plots. power-density spectra, power-distribution functions, a three-dimensional surface of power-frequency-time, sections of these three-dimensional surfaces, and a three-dimensional power-distribution surfaces. Note is made that each representation is useful for indicating specific acoustical characteristics which may be important when either comparing or describing sounds. The spectra provide an accurate means for estimating the parameters of the model and provide clearer comparisons when compared to the time-amplitude plots. This fact is most clearly shown by the three-dimensional powerdifference surface. This surface provides a very convenient means for the overall comparison of two sounds.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443743
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    In vitro velocity measurements down strem from the lonescu-Shiley aortic bioprosthesis in steady and pulsatile flow (1986)
    Springer
    Medical & biological engineering & computing 24 (1986), S. 449-459 
    Details
    ISSN: 1741-0444
    Keywords: Laser-Doppler anemometry ; Prosthetic heart valve ; Pulsatile flow ; Velocity measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Velocity measurements were made in vitro using laser Doppler anemometry (LDA) downstream from an lonescu-Shiley (IS) bioprosthetic aortic heart valve. Velocity measurements were made in both steady and pulsatile flow. A systematic, flow mapping approach to the measurement methodology showed that the IS valve generated a large jetlike flow constriction. The acceleration ratio, defined as the maximum mean velocity for the IS valve divided by that for no valve obstructing the flow, was as high as 2·4 for steady flow and 2·6 for pulsatile flow. It was concluded that the IS valve generated a flow quite unlike that observed by other in vestigators for the natural human aortic valve, after which the leaflet design of the IS valve was modelled. In addition, a comparative analysis of steady and pulsatile results was undertaken. It was found that the pulsatile flow results for the systolic ejection interval could be divided into three phases, denoted early, mid, and late systole, as defined by the flow structure at the data plane location. Only during midsystole were the pulsatile flow results approximated by the steady flow results. Also, it was found that the magnitude of the flow disturbance measured in steady flow tended to be an upper bound on that measured for pulsatile flow.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443958
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Laser-doppler anemometer to study velocity fields in the vicinity of prosthetic heart valves (1979)
    Springer
    Medical & biological engineering & computing 17 (1979), S. 38-44 
    Details
    ISSN: 1741-0444
    Keywords: Laser-Doppler anemometer ; Prosthetic heart valve ; Shear/stress measurements ; Velocity measurements
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Laser-Doppler anemometry is relatively new technique which is used for measuring velocity fields. It has major applications in the field ofin vitro biofluid mechanics. The laser-Doppler anemometers have many advantages compared with the traditional hot-wire or hot-film anemometers which are still mainly used in studies of biofluid mechanics. A laser-Doppler anemometer (I.d.a) system which can be used to measurein vitro velocity and shear-stress profiles in the vicinity of prosthetic heart valves is described. Accurate velocity measurements in the vicinity of prosthetic heart valves are very scarce, and the use of I.d.a systems will facilitate acquisition of these data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02440952
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    Paper (German National Licenses)
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