SUMMARY Wheat and bailey plants were grown for 3 weeks in a constant environment chamber containing approximately atmospheric concentrations of carbon dioxide (0.03%) labelled with 14C. The roots of the plants were maintained under sterile or non‐sterile conditions in soil contained in sealed pots which were regularly flushed with air. This enabled the quantities of 14C‐labelled carbon dioxide produced in the soil by plant and microbial activity to be separately assessed. At harvest, the 14C and total carbon contents of the roots and shoots and of the water‐soluble and insoluble material present in the soil were measured. These procedures enabled both the amounts of organic materials released into soil by the roots of growing plants and the effects of micro‐organisms on the process to be determined. Under sterile conditions between 5 and 10% of the photosynthetically fixed carbon may be released by roots compared with 12–18% by the roots of plants growing in unsterilized soil. These latter values are equivalent to 18–25% of the dry matter increments of the plants. The results indicate also that the increased evolution of carbon dioxide by cropped as compared to fallow soils can largely be ascribed to the immediate utilization by micro‐organisms of substances released by roots.

Factors affecting the synthesis and properties of a new generation of fine particle low voltage phosphors in field emission displays are reviewed. The morphology and particle size, the composition and stoichiometry, the stability, together with the nature and shape of the particle surface, all play important roles in the performance of the final phosphor. Initial new results from novel synthetic methodology are presented and discussed. Their implications in the light of the known literature point the way to the successful conclusion of the current thrust of phosphor research for good red, green, and blue low voltage, high definition phosphors.

SUMMARYCereal plants were grown for 3 weeks under sterile conditions in solution culture with their roots either unrestricted or growing between glass ballotini.The exudation of both amino acids and carbohydrates was increased when the roots were grown through a solid medium and the total quantity exuded was equivalent to about 9% of the dry matter increment of the roots.

Salmonellosis in humans is a costly disease traditionally assumed to be associated with exposure to contaminated food. We have developed a farm-to-fork model that allows estimation of the human health costs and risks associated with Salmonella in pork. This analysis focuses on the stages of the pork production chain up to the point of producing a chilled pork carcass. The model predicts the number of human cases of salmonellosis associated with pork (mean, 99,430; 90% confidence interval, 20,970 to 245,560) and the corresponding social costs (mean, $81.53 million; 90% confidence interval, $18.75 million to $197.44 million). Sensitivity and scenario analyses suggest that changes in Salmonella status during processing are more important for human health risk and have a higher benefit:cost ratio when compared with on-farm strategies for Salmonella control. Specifically, benefit:cost ratios are less than 1 (indicating they are not likely to be profitable from a social economic perspective) for the on-farm strategies of vaccination and meal feeding, whereas rinsing carcasses at various temperatures with and without sanitizer all have benefit:cost ratios greater than 1 (indicating they are profitable from a social economic perspective). This type of modeling is useful for evaluation of the relative cost effectiveness of interventions at different points in the food chain when allocating limited food safety dollars and is best used for examining trends and alternative strategies rather than for providing definitive dollar value estimates of risk. The dollar value estimates must be considered in the context of the wide confidence intervals.