DETECTION OF BACILLUS CEREUS DIARRHEAGENIC TOXIN USING A RAT LIGATED INTESTINAL LOOP ASSAY

A study was performed to determine if the rat ligated intestinal loop assay could detect Bacillus cereus diarrheagenic toxin. The results obtained indicated that this assay system could be used for such a purpose but it was not as sensitive as the young rabbit ligated ileal loop assay. When rats were used, concentrating the cell free culture filtrate of B. cereus 30- to 40-fold was necessary to detect diarrheagenic toxin activity with the intestinal loop assay.     

Precipitation in Microscopic Cracks

It is shown that precipitation occurs in Griffith-type surface cracks in solids from solutions or from vapors under conditions in which a plane surface would be dissolved or vaporized. A reduction in the equilibrium vapor pressure at the crack tip from that of a plane surface is produced by the driving force to reduce the surface energy of the crack. An equation is derived relating vapor pressure at the tip of the crack to vapor pressure over an infinite plane. This relation is used in deriving an expression for the fill-up of cracks with time. Experimental data on the measurement of the retreat of the crack edge with time appear to be in good agreement with the derived expression. A discussion of the effect of such crack healing on the mechanical properties of the solids is included.     

UNCERTAINTY IN THE DEMPSTER-SHAFER THEORY: A CRITICAL RE-EXAMINATION

Measures of two types of uncertainty that coexist in the Dempster-Shafer theory are overviewed. A measure of one type of uncertainty, which expresses nonspecificity of evidential claims, is well justified on both intuitive and mathematical grounds. Proposed measures of the other types of uncertainty, which atlempt to capture conflicts among evidential claims, are shown to have some deficiencies. To alleviate these deficiencies, a new measure is proposed. This measure, which is called a measure of discord, is not only satisfactory on intuitive grounds, but has also desirable mathematical properties. A measure of total uncertainty, which is defined as the sum of nonspecificity and discord, is also discussed. The paper focuses on conceptual issues. Mathematical properties of the measure of discord are only slated; their proofs are given in a companion paper.¹⁵