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  • 11
    Electronic Resource
    Electronic Resource
    Intra and inter-person sources of variability in fat intake in a feeding trial of 14 men (1990)
    Springer
    European journal of epidemiology 6 (1990), S. 55-60 
    Details
    ISSN: 1573-7284
    Keywords: Dietary variability ; Fat intake
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract An impediment to analyzing the effect of nutritional factors on biologic processes or health status in human populations arises from the relatively small dietary differences that exist between individuals in relation to large periodic fluctuations in dietary intake and the imprecision with which diet is normally assessed. We report here on characteristics of dietary variability in a group of 14 young men who successfully completed an intervention study specifically designed to create large differences in fat intake between baseline and two dietary intervention-periods each lasting two months (during which safflower and coconut oil supplements were given). We found that in the second supplemental phase of the intervention inter-person sources of variability were greatly increased over the low-fat baseline values. For proportion of calories as fat it increased to 64.2% of total variance from 21.6% without supplementation; for saturated fatty acids, 47.3% from 17.7%; for polyunsaturated fatty acids, 62.4% from 22.8%; and for the P:S ratio, 71.5% from 21.6%. During the first intervention phase we observed only moderate changes. Reasons for the intervention phase differences in effect, implications for feeding trials designed to look at dietary fat effects, and the need for future studies aimed at clarifying these results are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00155550
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    Paper (German National Licenses)
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  • 12
    Electronic Resource
    Electronic Resource
    The inappropriateness of conventional use of the correlation coefficient in assessing validity and reliability of dietary assessment methods (1991)
    Springer
    European journal of epidemiology 7 (1991), S. 339-343 
    Details
    ISSN: 1573-7284
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Accuracy and precision of nutritional data are crucial in estimating effects in nutritional epidemiology. Because it is known that such data are usually flawed, studies have been designed to estimate both the validity of diet assessment methods in measuring “true” diet and the reliability of these methods in providing nutrient data that are at least reproducible. In these studies, validity and reliability have often been gauged by computing correlation coefficients between two or more estimates of diet and testing the coefficeint's departure from 0. We propose that the correlation coefficient may be inappropriate in these studies as a measure of association. If correlation coefficients are presented, we suggest that one should also present confidence intervals and test the departure of the coefficient from approximately 1 rather than 0. We have examined this approach using dietary data from various studies. We have computed 95% confidence intervals of the correlation coefficients and have tested Ho:rho=0.95 as an approximation of rho=1.00. In all of the studies selected, comparisons produced correlation coefficients statistically significantly different from both 0.95 and 0. Due to the dependence of the correlation coefficient on factors unique to individual studies, it is recommended that other techniques be used to assess agreement between nutrient scores derived in reliability or validation studies. Viable options include linear regression, analyses of the standard deviations of the differences between scores, and examinations of the intraclass correlation coefficient.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00144997
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    Paper (German National Licenses)
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  • 13
    Electronic Resource
    Electronic Resource
    Reinforcement characterization of metal matrix composites by DSC technique (1992)
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 989-996 
    Details
    ISSN: 1572-8943
    Keywords: aerospace industry ; DSC ; metal matrix composites (MMC)
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Metallmatrixverbundwerkstoffe (MMC) sind für die Raumfahrtindustrie von großem Interesse, insbesondere zum Bau thermisch-struktureller Komponenten ist es wichtig, Methoden zur Verfügung zu haben, die leicht und einfach zur Charakterisierung der mechanischen Festigkeit der Materialien benutzt werden können. Es wurde gezeigt, daß DSC es ermöglicht, die Kohäsionsenergie im Fiber/Matrix-Grenzflächengebiet eines mit SiC-Whiskern verstärkten Aluminiumverbundstoffes quantitativ zu bestimmen. Diese Kohäsionsenergie ist abgängig vom Verstärkungsgrad bezogen auf die Matrixfestigkeit und berücksichtigt sowohl die chemischen als auch mechanischen Eigenschaften der Kohäsion im Fiber/Matrix-Grenzflächengebiet. In jedem Falle bedarf diese Methode einer systematischen Kalibrierung anhand von Test der mechanischen Eigenschaften.
    Notes: Abstract The metal matrix composites (MMC) being of very high interest for the aerospace industry, particularly to build up thermal-structural components, it is important to have available methods which are easy and simple to conduct for characterization of the mechanical strength of the material. This study shows that the differential scanning calorimetry (DSC) may enable us to quantify the energy of cohesion in the fiber/matrix interface area of an aluminium composite reinforced by SiC whiskers. The energy of cohesion is dependent on the state of reinforcement compared to the matrix strength and take into account both chemical and mechanical characteristics of the cohesion in the fiber/matrix interface area. However, this method would require a systematic calibration based on tests of mechanical characteristics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01979432
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    Paper (German National Licenses)
    Fulltext
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