The enumeration of coliforms and E. Coli on naturally contaminated beef: A comparison of the petrifilm(™) method with the Australian Standard

Petrifilm(?) PEC was compared to Australian Standard (AS) methods for the enumeration of coliforms and Escherichia coli on 50 naturally contaminated beef samples from three meat works. The standard methods consist of a 3-tube most probable number test or a direct plate count on tryptone bile agar for E. coli, and violet red bile agar and the most probable number test for conliorms (AS 1766.2.12.1984 and AS 1766.2.3.1992). No significant difference was found between the methods, except that the count of E. coli on the direct plate method with a resuscitation step was significantly higher than the count on Petrifilm(?), most probable number or direct plate count without resuscitation.     

Effect of differential instructional set on sentence completion responses.

Studied the effects of 4 different instructional sets on Sentence Completion Test (SCT) responses. 4 groups of 25 16-18 yr. old males received different instructions to similar SCT items: (a) stressing the expression of real feeling, (b) asking for immediate response, (c) encouraging both immediate response and real feeling, and (d) neutral instructions. Results suggest that differential instructional set has no significant overall effect on sentence-completion responses, although some item clusters were more susceptible than others to variations in instructional set. While findings demonstrate no difference in mean scores by the authors' method of scoring various types of SCT instructions, the possibility cannot be ruled out that there may be differences in validity. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

A criterion for the time dependence of dynamic fracture

Dynamic fracture is a time-dependent phenomena in which the spall stress depends on the stress pulse duration. It is shown that the empirical relation between the spall stress and the square root of the stress gradient is equivalent to a simple impulse criterion. A more general criterion based on the concept of cumulative damage is proposed, and good agreement is obtained between calculated and observed values of the spall layer thickness in aluminum.

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Zusammenfassung Ein dynamischer Bruch ist eine zeitabhängige Erscheinung, wo die Absplitterspannung von der Dauer des Stosses ab:hangt. Es wind gezeigt, dass die empirische Beziehung zwischen der Absplitterspannung und der Quadratwurzel des Spannungsgefälies einem einfachen Impulskriterium equivalent ist. Ein allgemeineres Kriterium wird aufgestellt and vorgeschlagen, das auf den Begriff eines Sammelschadens beruht, und eine gute Ubereinstimmutag wird erlangt zwischen den berechneten und experimentell beobachteten Werten der Absplitterungsschichtdicke im Aluminium.

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Résumé Une rupture dynamique est un phénomène qui dépend du temps et dans lequel la contrainte d'déaillage est une fonction de la duree du choc. II a été démontre que la relation empirique entre la contrainte d'écaillage est la racine carrée du gradient d'décaillage équivaut un simple critère d'impulsion. Nous proposons un critère plus général, basè sur le concept d'un dommage cumulatif, ayant obtenu un bon raccordement entre les valeurs calculées et expérimentalement observées de l'épaisseur d'une couche d'écaillage dans l'aluminium.

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This work was supported by the United States Atomic Energy Commission.     

边坡控制爆破的设计与实施

本文在分析边坡稳定性影响因素及其破坏机理的基础上，提出了几种有效的边坡控制爆玻设计，以及要取得最佳爆破效果所必须采取的措施。