Data on coal-burning endemic fluorosis throughout China and on the exposure-response relationship between concentrations of fluoride determined in coal samples and the prevalence of dental fluorosis reported from 17 representative surveillance stations in Southwest China were used to estimate the safety threshold for coal fluoride. Coal-burning endemic fluorosis occurs mainly in the mountainous...

For any software system upon which lives depend, the most important question one can ask about it is, ‘How do we know the system is safe?’ Despite the critical importance of this question, no widely accepted, generally applicable answer exists. Instead, debate continues to rage over the question, with theorists and practitioners quarrelling with each other and amongst themselves. This paper sug...

______________________________________________________________________________ Abstract: Probabilistic safety requirements currently formulated or proposed for space systems, nuclear reactor systems, nuclear weapon systems, and other types of systems that have a low probability potential for high consequence accidents depend on showing that the probability of such accidents is below a specified...

Lay people have difficulty understanding the meaning of environmental health risk information. Visual images can use features that leverage visual perception capabilities and semiotic conventions to promote meaningful comprehension. Such evidence-based features were employed to develop two images of a color-coded visual scale to convey drinking water test results. The effect of these images and...

2-D threshold function f is a function defined on the integer interior of a rectangular area [0, m] × [0, n] on a plane and takes values from the set {0, 1} such that there is a straight line separating the pre-images f −1 (0) and f −1 (1). For the number of such functions only asymptotic bounds were known. We give an exact formula for the number of 2-D threshold functions and derive an asympto...

The multiple-look notion holds that the difference limen (DL) decreases with multiple observations. We investigated this notion for temporal discrimination in isochronous sound sequences. In Experiment 1, we established a multiple-look effect when sequences comprised nine standard time intervals (S) followed by an increasing number of comparison time intervals (C), but no multiple-look effect w...

Safety critical systems often have shutdown mechanisms to bring the system to a safe state in the event of a malfunction. We examine the use of ride-through, a technique to reduce the frequency of safety shutdowns by allowing small transient violations of safety rules. An illustrative example of enforcing a speed limit for an autonomous vehicle shows that using a rate-limited ride-through bound...