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  • 1990-1994  (2)
  • 1975-1979  (2)
  • 1960-1964  (3)
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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 27 (1990), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: The empirical literature has shown that respiratory sinus arrhythmia is a sensitive noninvasive index of parasympathetic cardiac control. Nevertheless there has been no general agreement among investigators as to the most preferable quantification technique for assessing respiratory sinus arrhythmia, although there has been much speculation that specific estimation techniques are more or less reflective of vagal processes and could be more or less contaminated by other influences upon heart period variability unrelated to respiration. This study compared three quantification procedures for estimating respiratory sinus arrhythmia (RSA): (1) a spectral analytic technique, (2) a complex detrending approach removing periodic and aperiodic cardiac variations unrelated to respiration, and (3) a time-domain, peak-valley procedure employing inspiratory and expiratory periods as windows for determining range of cardiac-interval fluctuations associated with respiratory phase. Measures derived from these techniques were intra- and interindividually compared using three different samples of male subjects, including students, adult normotensives, and adult hypertensives. All interindividual correlations between measures yielded coefficients above .92 and the mean within-subject correlation across 42 individuals was .96, thus indicating a marked degree of comparability between measures. Additionally, given that much evidence indicates lawful within-individual relations between RSA amplitude and respiratory parameters, we employed respiratory period as an external criterion and compared intraindividual correlations between this variable and (2) and (3); results showed that (3) was significantly more highly associated with respiration than was (2), although the mean r's for the two measures did not diverge greatly (.91 vs. 84). Finally, inspection of the data and further regression analyses did not suggest that any of the RSA estimates were differentially contaminated by other components of cardiac variability. Our findings suggest that the three techniques are almost equivalent as indices of cardiac vagal tone and would appear to ease concerns about the inferiority of any of the procedures. Choice of a quantification procedure should therefore be tailored to the specific empirical needs of an investigation. The advantages and disadvantages of each method are discussed.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 27 (1990), S. 0 
    ISSN: 1469-8986
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine , Psychology
    Notes: This study addresses a number of unresolved issues regarding the employment of respiratory sinus arrhythmia as an index of tonic parasympathetic cardiac control in psychophysiological investigations. These questions include the following: (1) Does respiratory sinus arrhythmia reflect cardiac vagal tone under conditions in which alterations in parasympathetic control are expected to be mild to moderate? (2) Are variations in human respiratory sinus arrhythmia that occur in response to varying behavioral demands independent of beta-adrenergic effects on the heart? (3) To what extent do typical experimental tasks apparently affect tonic cardiac vagal control?Twelve healthy male subjects were administered a joint alpha- and β-adrenoreceptor pharmacological blocker on one day and a placebo on another (balanced across subjects). On both days, respiratory sinus arrhythmia and heart period were monitored during a number of different experimental tasks while subjects continuously paced their respiration.Results indicated that respiratory sinus arrhythmia, under controlled respiratory conditions, is uninfluenced by variations in sympathetic activity, and provides a reasonably sensitive index of cardiac vagal tone, even when alterations in parasympathetic tone are not large. Furthermore, our findings suggest that cardiac vagal tone is responsive to varying behavioral demands and may interact in different ways with β-adrenergic mechanisms.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Wood science and technology 10 (1976), S. 163-168 
    ISSN: 1432-5225
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The author reviews characteristic features of the effect of simultaneous moisture change and load on the deformation of wood and discusses their implications for any model based on the botanical and molecular structure of wood.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Colloid & polymer science 174 (1961), S. 97-109 
    ISSN: 1435-1536
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Description / Table of Contents: Zusammenfassung Das vorgeschlagene Postulat schränkt die Richtungen ein, in denen die Spannung in einem verformten Kontinuum wirken darf. Die Herleitung erweist sich als besonders einfach, wenn die Beschreibung der Verformung geändert und, ebenso wie die Spannung, auf ebene Flächen bezogen wird. Das Postulat ist dann als lineare Abhängigkeit der Spannungsvektoren von den Vektoren gegeben, die die kinematische Vorgeschichte der Fläche beschreiben. Diese Theologische Zustandsgleichung wurde bereits vonWeissenberg in verschie dener Weise ausgedrÜckt und ist von besonderem Interesse fÜr elastische Körper oder fÜr die erholungsfähigen Komponenten viskoelastischer Körper. Die bereits bekannten sowie neue AusdrÜcke fÜr die Gleichung werden entwickelt und als gleichwertig erwiesen. Eines der „Elastizitätsgesetze“ bestimmt die Richtungen der Normal-, Tangential- und Querkomponenten des Spannungsvektors an einer gegebenen Fläche; andere Gesetze vergleichen die absoluten Grö\en dieser Komponenten an verschiedenen Flächen, die den Versuchspunkt enthalten. Weitere Gesetze bestimmen Beziehungen zwischen Spannungs- und Verformungstensoren oder beschränken die Wahl einer Verformungspotentialfunktion. Die Übereinstimmung der vorgeschlagenen Theologischen Zustandsgleichung mit anderen Elastizitätsgesetzen und mit Ergebnissen von Experimenten wird untersucht.
    Notes: Summary The proposed postulate restricts the allowable directions of traction forces in a deformed continuous medium. It can best be formulated when the description of strain is modified to refer, as stress does, to plane areas. The postulate may then be expressed as a linear dependence of the traction force on the vectors that describe the kinematic history of the area. This rheological equation of state has previously been given byWeissenberg in various forms and is of particular interest for elastic media, or the recoverable component of visco-elastic media. Its previous formulations and some new ones are derived and shown to be all equivalent. One “elasticity law” determines the directions of the normal, tangential and cross components of the traction force on any given plane; others compare the magnitudes of these components for different planes through a test point. Further laws provide stress-strain relations or restrict the choice of a strain potential. The consistence of these formulations of the proposed equation of state with other elasticity laws and with experimental evidence is discussed.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1434-6052
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have investigated the properties of off-shell $$\bar K$$ K and $$\bar p$$ p annihilations into pions by using the interactionsK − p → Λ + pions at 4.2 GeV/c. The properties considered are multiplicities, hadronic temperatures and angular distributions. These properties appear more akin to those of $$\bar p$$ p annihilations in flight than to that of $$\bar p$$ p annihilation at rest despite the fact that the annihilation energy is small.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Rheologica acta 2 (1962), S. 66-74 
    ISSN: 1435-1528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Zusammenfassung Beschrieben wird eine Reihe von Modellexperimenten über die Ausbildung von Ermüdungsfiguren in einem isotropen Material (Pulverschichten), welches an einer deformierbaren Membran haftet, die einer periodischen Dehnung unterworfen wird, wobei die Amplituden, relativen Phasen und Frequenzen innerhalb der Berührungsebene kontrolliert werden Bei hinreichend großen Amplituden entsteht auf der Pulveroberfläche ein Muster von Riffeln, deren Anwachsen und nachfolgende Aufspaltung im einzelnen beobachtet werden kann. Gestalt, Höhe, Periodizität und Orientierung dieser Riffeln werden zu den oben genannten Parametern in Beziehung gesetzt. Die beschriebenen Versuche stellen nur die ersten Schritte einer neuen Behandlungsweise des Ermüdungs- und Fehlordnungsproblems dar, und man kann hoffen, daß durch die weitere Entwicklung der Bereich der durch die Methode der flexiblen Grenzfläche zu untersuchenden Stoffe noch erheblich vergrößert werden wird.
    Notes: Summary A series of model experiments is described on the development of fatigue patterns in an isotropic material (a powder aggregate) adhering to a deformable membrane subjected to cycles of strain whose amplitudes, relative phases and frequencies, are controlled in the two dimensions of the contact plane. At sufficiently large amplitudes, a pattern of ridges develops on the surface of the powder and their growth and subsequent fission can be observed in detail. The shape, height, periodicity, and orientation of these ridges are investigated in relation to the strain parameters listed above. The present experiments are only early steps in a novel approach to the problem of fatigue and failure and it is hoped that further development will widely extend the range of materials that can be tested by the flexible boundary technique.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    Journal of Polymer Science 46 (1960), S. 257-259 
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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