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  • Elasticity
  • Schopper
  • Springer  (13)
  • American Meteorological Society
  • Springer Nature
  • 2015-2019
  • 1980-1984  (9)
  • 1975-1979  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    Direct turgor pressure measurements in individual leaf cells of Tradescantia virginiana (1980)
    Springer
    Planta 149 (1980), S. 445-453 
    Details
    ISSN: 1432-2048
    Keywords: Elasticity ; Hydraulic conductivity ; Leaf cells ; Tradescantia ; Turgor pressure
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The water relations of leaves of Tradescantia virginiana were studied using the miniaturized pressure probe (Hüsken, E. Steudle, Zimmermann, 1978 Plant Physiol. 61, 158–163). Under well-watered conditions cell turgor pressures, P o, ranged from 2 to 8 bar in epidermal cells. In subsidiary cells P o was about 1.5 to 4.5 bar and in mesophyll cells about 2 to 3.5 bar. From the turgor pressure, relaxation induced in individual cells by changing the turgor pressure directly by means of the pressure probe, the half-time of water exchange was measured to be between 3 and 100 s for the epidermal, subsidiary, and mesophyll cells. The volumetric elastic modulus, ε, of individual cells was determined by changing the cell volume by a defined amount and simultaneously measuring the corresponding change in cell turgor pressure. The values for the elastic modulus for epidermal, subsidiary, and mesophyll cells are in the range of 40 to 240 bar, 30 to 200 bar, and 6 to 14 bar, respectively. Using these values, the hydraulic conductivity, L p, for the epidermal, subsidiary, and mesophyll cells is calculated from the turgor pressure relaxation process (on the basis of the thermodynamics of irreversible processes) to be between 1 and 55·10-7 cm s-1 bar-1. The data for the volumetric elastic modulus of epidermal and subsidiary cells indicate that the corresponding elastic modulus for the guard cells should be considerably lower due to the large volume changes of these cells during opening or closing. Recalculation of experimental data obtained by K. Raschke (1979, Encycl. Plant Physiol. N.S., vol. 7, pp 383–441) on epidermal strips of Vicia faba indicates that the elastic modulus of guard cells of V. faba is in the order of 40–80 bar for closed stomata. However, with increasing stomatal opening, i.e., increasing guard cell volume, ε decreases. Therefore, in our opinion Raschke's results would indicate a relationship between guard cell volume and ε which would be inverse to that for plant cells known in the literature. ε assumes values between 20–40 bar when the guard cell colume is soubled.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385746
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  • 2
    Electronic Resource
    Electronic Resource
    Turgor pressure and water transport properties of suspension-cultured cells of Chenopodium rubrum L. (1981)
    Springer
    Planta 151 (1981), S. 95-102 
    Details
    ISSN: 1432-2048
    Keywords: Cell suspension culture ; Chenopodium ; Elasticity ; Immobilization ; Pressure probe ; Water relations
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The turgor pressure and water relation parameters were determined in single photoautotrophically grown suspension cells and in individual cells of intact leaves of Chenopodium rubrum using the miniaturized pressure probe. The stationary turgor pressure in suspension-cultured cells was in the range of betwen 3 and 5 bar. From the turgor pressure relaxation process, induced either hydrostatically (by means of the pressure probe) or osmotically, the halftime of water exchange was estimated to be 20±10 s. No polarity was observed for both ex- and endosmotic water flow. The volumetric elastic modulus, ε, determined from measurements of turgor pressure changes, and the corresponding changes in the fractional cell volume was determined to be in the range of between 20 and 50 bar. ε increases with increasing turgor pressure as observed for other higher plant and algal cells. The hydraulic conductivity, Lp, is calculated to be about 0,5–2·10−6 cm s−1 bar−1. Similar results were obtained for individual leaf cells of Ch. rubrum. Suspension cells immobilized in a cross-linked matrix of alginate (6 to 8% w/w) revealed the same values for the half-time of water exchange and for the hydraulic conductivity, Lp, provided that the turgor pressure relaxation process was generated hydrostatically by means of the pressure probe. Thus, it can be concluded that the unstirred layer from the immobilized matrix has no effect on the calculation of Lp from the turgor pressure relaxation process, using the water transport equation derived for a single cell surrounded by a large external volume. By analogy, this also holds true for Lp-values derived from turgor pressure changes generated by the pressure probe in a single cell within the leaf tissue. The fair similarity between the Lp-values measured in mesophyll cells in situ and mesophyll-like suspension cells suggests that the water transport relations of a cell within a leaf are not fundamentally different from those measured in a single cell.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00384243
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  • 3
    Electronic Resource
    Electronic Resource
    Charging versus exclusion: Choice between recreation management tools (1981)
    Springer
    Environmental management 5 (1981), S. 161-175 
    Details
    ISSN: 1432-1009
    Keywords: Charging ; Exclusion ; Recreation management ; Consumers' surplus ; Distribution of recreational opportunity ; Substitute sites ; Intuitive expectations ; Visit rate ; Site carrying capacity ; Equilibrium price ; Elasticity ; Utility functions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract Overuse of recreation sites seems to justify regulation, and the principal tools for this are fee charging or physical exclusion. Both seem equally costly to administer. Both involve equal costs to consumers if recreationists visit from one origin, but if they come from different origins, costs may be greater and consumers' surplus less under either tool, depending on the shape of the demand curve. Which is the more equitable tool depends on the relative representation of rich and poor participants from near and distant origins. Potentially beneficial use of site revenues is an advantage of charging. Neither availability of substitutes nor variation in daily demand seems likely to change these results substantially, but a system of booking admissions before the trip outset might neutralize the advantages of charging. The optimal level of use varies with the regulatory tool chosen. The optimal admissions under exclusion could be fewer than or more than under charging, or may even be equal to unregulated use.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01867335
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  • 4
    Electronic Resource
    Electronic Resource
    Viscoelastic properties of the wrist motor servo in man (1984)
    Springer
    Annals of biomedical engineering 12 (1984), S. 599-620 
    Details
    ISSN: 1573-9686
    Keywords: Stretch reflex ; Muscle ; Elasticity ; Viscosity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Viscoelastic properties play an important role in posture and movement. Such properties arise from muscle mechanics and from stretch-reflex actions. We describe experiments designed to characterize both linear and nonlinear elastic and viscous properties of the wrist motor servo in human subjects. First, we describe a trial comparison method for the identification of reflex responses that are unmodified by triggered reaction-time movements. Elastic properties were studied by applying step changes in load force that stretched or released the wrist flexor and extensor muscles. The properties were basically spring-like, but there was a short-range enhancement of stiffness that gave rise to a prominent hysteresis. Viscous properties were studied by applying ramp stretches at different velocities. Both EMG and force responses showed a weak fractional-power dependence on velocity similar to that described recently for muscle spindle receptors. Consideration is given to the possible advantages of this type of nonlinear feedback in the damping of postural responses and movements.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02371452
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  • 5
    Electronic Resource
    Electronic Resource
    Elastic modulus of the human intact left ventricle—determination and physiological interpretation (1975)
    Springer
    Medical & biological engineering & computing 13 (1975), S. 151-161 
    Details
    ISSN: 1741-0444
    Keywords: Elasticity ; Human left ventricle ; Modulus ; Stress/strain ; Thick-walled model
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire Le ventricule gauche (VG) est représenté par une enveloppe musculaire dont la performance est caractérisée par la pression de la chambre et la contrainte et la déformation sur la paroi ventriculaire; le module d'élasticité ventriculaire effectif du VG décrit la relation entre ces variables de la performance et représente donc la fonction du transfer du système physiologique du ventricule gauche. On présente une méthode de détermination indirecte du module effectifE du ventricule gauche. La méthode fait usage d'un modèle mathématique à paroi épaisse du VG et ayant un milieu isotropique homogène. On détermine des valeurs instantanées deE pour des sujets atteints de maladies cardiaques à étiologies variables, de façon à évaluer la réponse du VG aux surcharges chroniques de pression et de volume. Les valeurs résultantes deE sont utilisées diagnostiquement pour caractériser l'état physiologique du VG. Des valeurs normales de,E à la systole indiquent que la force de la contraction exercée par le VG est normale et qu'il s'est donc ajusté à la maladie cardiaque.
    Abstract: Zusammenfassung Das linke Ventrikel (LV) wird als Muskelschale dargestellt, dessen Leistung durch Kammerdruck und Beanspruchung der Ventrikulärwand beschrieben wird. Das effektive elastische Modul des LV bringt diese Leistungsvariablen aufeindander in Bezug und stellt daher die Ubertragungsfunktion des linken physiologischen Ventrikelsystems dar. Es wird ein Verfahren zur indirekten Bestimmung des effektiven Moduls (E) für das linke Ventrikel dargestellt. Das Verfahren verwendet das starkwandige mathematische Modell eines LV mit einem homogenen isotropen Medium. Sofortige E-Werte werden für Fälle mit Herzkrankheiten verschiedener Ursachen betimmt, um die Reaktion des LV auf chronische Überbelastung durch Druck und Volumen zu beaurteilen. Die sich für E ergebenden Werte werden diagnostisch dazu verwendent, den physiologischen Zustand des LV zu bestimmen. Normale Werte für E bei Systole bedeuten, daß die vom LV ausgeführte Kontraktion normal stark ist, was bedeutet, daß sich das LV auf die Herzkrankheit eingestellt hat.
    Notes: Abstract The left ventricle (l.v.) is represented as a shell of muscle whose performance is characterised in terms of the chamber pressure and stress/strain in the ventricular wall; the effective elastic modulus of the l.v. relates these peerformance variables, and hence represents the transfer function of the left ventricular physiological system. A method is presented for indirectly determining the effective modulusE for the left ventricle. The method employs a thick-walled mathematical model of the l.v. having a homogeneous isotropic medium. Instantaneous values ofE are determined for subjects with heart diseases of varied etiologies, in order to assess the responses of the l.v. to chronic overloads of pressure and volume. Resulting values forE are used diagnostically to characterise the physiological state of the l.v. Normal values ofE, at systole, indicate that the strength of contraction exercised by the l.v. is normal, and hence is an indication of the l.v. having adjusted to the heart disease.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02477722
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  • 6
    Electronic Resource
    Electronic Resource
    Elastic and strength properties of canine long bones (1977)
    Springer
    Medical & biological engineering & computing 15 (1977), S. 72-74 
    Details
    ISSN: 1741-0444
    Keywords: Bone ; Elasticity ; Mechanical strength
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Summary The mechanical properties of canine long bones have been determined. The mean and standard deviation of the maximum load supported by six fresh canine femurs in 3-point bending was 1366±253 N. In all cases, the bones sustained a considerable amount of plastic deformation before failure. The modulus of elasticity (GN/m2), ultimate tensile stress (MN/m2) and yield stress (MN/m2) were 13·86, 108·3 and 88·3 for six humeral specimens and 13·88, 142·1 and 104·0 for 13 tibial specimens, respectively. The tibial specimens showed a statistically significant higher ultimate strength than the humeral specimens.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441578
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  • 7
    Electronic Resource
    Electronic Resource
    Hydrodynamics of blood flow through the inferior vena cava (1977)
    Springer
    Medical & biological engineering & computing 15 (1977), S. 248-253 
    Details
    ISSN: 1741-0444
    Keywords: Elasticity ; Haemodynamics ; Inferior vena cava ; Negative-resistance effects
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Description / Table of Contents: Sommaire La veine cave inférieure est un vaisseau affaissable soumis á des variations de la pression de respiration. Les observations cliniques sur le corps humain démontrent que, au cours d'une aspiration profonde, l'accroissement de la pente de pression propulsive provoque l'affaissement de la veine cave inférieure près du diaphragme, et réduit paradoxalement la circulation sanguine. Les empreintes faites au cours des autopsies démontrent qu'il se produit une constriction élastique fortement localisée à l'endroit où la veine cave inférieure, traverse le diaphragme. Un modèle mécanique passif, comportant une constriction élastique semblable, présente le même comportement paradoxal de résistance négative, conformément aux principes de l'écoulement à travers des tubes affaissables.
    Abstract: Zusammenfassung Die Vena cava inferior ist ein kollabierendes Gefäss, das Respirationsdruckschwankungen unterliegt. Klinische Beobachtungen an Menschen zeigen, dass ein Anstieg in dem propulsiven Druckgefälle bewirkt, dass die untere Hohlvene nahe der Membrane kollabiert und paradoxerweise daher den Blutstrom reduziert. Postmortale Abbildungengen zeigen, dass eine stark lokalisierte elastiche Verengung daher den Blutstrom reduziert. Postmortale Abbildungen zeigen, dasse eine stark lokalisierte elastische Verengung eintritt, wo die untere Hohlvene durch die Membrane führt. Ein passives mechanisches Modell mit einer ähnlichen elastischen Verengung zeigt ein ähnliches paradoxes oder negatives Widerstands-Verhalten, das den Prinzipien über den Strom durch kollabierende-Gefässe entspricht.
    Notes: Abstract The inferior vena cava (i.v.c.) is a collapsible vessel which is subject to respiratory pressure variations. Clinical observations on humans show that, during deep inspiration, an increase in the propulsive pressure gradient causes the i.v.c. to collapse near the diaphragm and paradoxically reduces the blood flow. Postmortem casts show that there is a sharply localised elastic constriction where the i.v.c. passes through the diaphragm. A passive mechanical model, incorporating a similar elastic constriction, exhibits similar paradoxical or negative-resistance behaviour, which is in accordance with the principles governing flow through collapsible tubes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02441045
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  • 8
    Electronic Resource
    Electronic Resource
    Reflection from elastic discontinuities (1983)
    Springer
    Medical & biological engineering & computing 21 (1983), S. 697-701 
    Details
    ISSN: 1741-0444
    Keywords: Elasticity ; Pressure pulse ; Propagation ; Reflection
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract Elastic mismatching is studied by an impulse technique. Elastic mismatches are created by joining two latex rubber tubes of the same internal diameter but different wall thickness. A short duration pressure impulse is generated at the entrance of the water-filled tube system and the transmission characteristics of the impulse are determined from a series of measurements along the tube system using a catheter-tip pressure manometer. This technique enables the magnitude and phase change of the reflection at the elastic discontinuity to be obtained. A number of tube combinations are examined and in all cases a good agreement is shown between the measured reflection coefficient and the value calculated theoretically.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02464032
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  • 9
    Electronic Resource
    Electronic Resource
    In vivo stiffness properties of the canine diaphragm muscle (1980)
    Springer
    Medical & biological engineering & computing 18 (1980), S. 625-632 
    Details
    ISSN: 1741-0444
    Keywords: Diaphragm ; Elasticity ; Modulus ; Muscle ; Passive
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology , Medicine
    Notes: Abstract A measuring system used to monitor the orthogonal stresses and strains in the plane of the passive canine diaphragm musclein vivo is described. The system consists of four topically applied force-displacement transducers, a laser-camera subsystem to determine the local radii of curvature and an abdominally situated pressure transducer. Experimental results show that the passive musclein situ behaves as an anisotropic linearly elastic material for loads in the physiological range. A model is proposed which describes the diaphragm's response to load in terms of two moduli. Values obtained experimentally for the moduli are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02443135
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  • 10
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    Physical Properties of Rocks (1982)
    Springer
    In:  Berlin, Springer, vol. V/1, subvol. a, pp. 559-932, (ISBN 0-935702-96-2)
    Details
    Publication Date: 1982
    Keywords: Rock mechanics ; Physical properties of rocks ; Handbook of geophysics ; Laboratory measurements ; density ; porosity ; elasticity ; electrical ; magnetic ; properties ; radioactivity ; moon ; ice ; Czermak ; Huckenholz ; Rybach ; Schmid ; Schopper ; Schuch ; Stoeffler ; Wohlenberg
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    BIBLIOGRAPHY SEISMOLOGY
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