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  • 1990-1994  (2)
  • 1985-1989  (2)
  • 1970-1974  (4)
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  • 1
    Electronic Resource
    Electronic Resource
    A Comparison of Three Quantification Methods for Estimation of Respiratory Sinus Arrhythmia (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 27 (1990), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1469-8986.1990.tb03198.x
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Paced Respiratory Sinus Arrhythmia as an Index of Cardiac Parasympathetic Tone During Varying Behavioral Tasks (1990)
    Oxford, UK : Blackwell Publishing Ltd
    Psychophysiology 27 (1990), S. 0 
    Details
    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
    URL: http://dx.doi.org/10.1111/j.1469-8986.1990.tb02335.x
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    U. Grigull zum 60. Geburtstag (1972)
    Springer
    Heat and mass transfer 5 (1972), S. 1-2 
    Details
    ISSN: 1432-1181
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01000471
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Deflection of wood under intermittent loading (1987)
    Springer
    Wood science and technology 21 (1987), S. 349-360 
    Details
    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: Summary The study of intermittent loading of wood described in an earlier publication was extended to explore the effects of shorter cycles. For stresses below about 50 per cent of the modulus of rupture the principle of superposition provides a fair indication of expected deflections when the environmental conditions are constant. It is shown how, under this principle, the peak strains are limited to fractions of the creep strain at constant load, the excess after the first peak being dependent on the proportion of time under load in a cycle. Consequently, when the intervals between loads are considerably longer than the duration of loads, cumulative effects are negligible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00380202
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    Paper (German National Licenses)
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  • 5
    Electronic Resource
    Electronic Resource
    Compression fracture of wood parallel to the grain (1971)
    Springer
    Wood science and technology 5 (1971), S. 147-156 
    Details
    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: Summary A theoretical model of wood is presented consisting of a bonded assembly of long hollow tubes. As increasing load is applied to the tubes in the direction of their length, it is assumed that the bonding material breaks until sufficient free lengths exist for portions of the tubes to buckle. The dependence of the buckling stress and the free length on dimensions and properties of the tubes is calculated and the angle of the band of unstable portions is derived. The behaviour of the model is compared with the measured behaviour of wood. Agreement is encouraging and refinements are suggested to reduce the discrepancies observed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01134225
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    Paper (German National Licenses)
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  • 6
    Electronic Resource
    Electronic Resource
    Use of Leicester's “rheological model for mechano-sorptive deflections of beams” (1971)
    Springer
    Wood science and technology 5 (1971), S. 232-235 
    Details
    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: Summary The model for mechano-sorptive deformation proposed by Leicester is used to predict stress relaxation of wood drying under constraint from apparent creep of drying wood under constant load. The predictions are compared with measurements on four pairs of beams, one beam in each pair being tested under constant load, the other at constant deflection. Agreement was sufficiently close to demonstrate the value of the model.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00353685
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    Paper (German National Licenses)
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  • 7
    Electronic Resource
    Electronic Resource
    The behaviour of particle board and hardboard beams during moisture cycling (1972)
    Springer
    Wood science and technology 6 (1972), S. 128-137 
    Details
    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: Summary The effects of creep at constant conditions of moisture content and the effects of deformations occurring during cycling of moisture content have been studied in loaded beams of particleboard and hardboard. The variations in stiffness in loaded and unloaded beams of particleboard during moisture cycling were also determined. Contrary to the findings of some workers but in agreement with the findings of another, the increases in the deflections of loaded beams of particleboard during cycling of moisture content were due mainly to desorption of moisture. Qualitatively similar behaviour was found for particleboard, hardboard and wood but quantitatively the effects were greatest in particleboard and hardboard. It appears that the basic mechanism of the transient effects in bending, arising with the simultaneous action of load and change in moisture content, may be similar in wood, particleboard and hardboard.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00350826
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    Paper (German National Licenses)
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  • 8
    Electronic Resource
    Electronic Resource
    Compact, simple stress-relaxation equipment (1985)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 30 (1985), S. 1773-1775 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1985.070300441
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    Paper (German National Licenses)
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