Ten subjects with WAIS Full Scale IQ scores ranging from 119 to 47 were required to discriminate between two lines of markedly different length, exposed in random order for ten different durations, by pressing one of two keys. Estimates of inspection time gamma, the rate at which sensory input is accumulated and passed to subsequent decision processes, were calculated directly from the psychometric functions obtained gamma was found to correlate negatively with subtests contributing to Performance IQ. There was a substantial degree of consistency between estimates of gamma on two different occasions and training did not appear to affect the index, although differences between the two estimates increased as the value of the first estimate increased. Mean overall response latency did not correlate significantly with intelligence and measures obtained from retarded subjects were very like those reported in similar experimental situations utilizing normal subjects. This unexpected finding is interpreted as suggesting that, in this situation, retarded subjects have been prepared to respond on the basis of less evidence than is usually required by intellectually normal subjects.

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Currently, on average, one tire is discarded in the U.S. for every man woman and child every year. While the reuse market for used tires has increased over the years to approximately 75%, there are still an estimated 2-3 billion used tires stockpiled in the U.S. Finding economical and sustainable end uses for this tire material is an ongoing challenge to environmental engineers and others. In this study, three different uses of tire rubber were evaluated as biofilm attachment media in bioreactors for wastewater treatment: in an aerobic biofilter, in anoxic bioreactor, and in a hybrid anaerobic static granular bed reactor (SGBR). Size distribution, chemical composition, scanning electron microscopy, and whole effluent toxicity analyses were performed. These tests demonstrated that the tire rubber media was non-toxic and provided good surface area for biofilm attachment. The trickling filter system using chunk rubber (average diameter of approximately 3 cm) achieved 79.6-90.1% COD removal efficiency at organic loading rates ranging from 0.12 kg COD/m 3 •d to 0.34 kg COD/m 3 •d. In the hybrid SGBR, anaerobic granular sludge was augmented with fine rubber particles (average particle diameter of approximately 0.2 mm) and achieved greater than 90% COD removal at hydraulic retention times of 48 to 20 h resulting in organic loading increases from 0.44 to 2.7 kg/m 3 •d. The anoxic TDRP filter system achieved nitrate-nitrogen removal efficiencies greater than 97% at influent concentrations ranging from 52 to 94 mg NO 3-N/L. This research demonstrated the utility of TDRP media in multiple biofiltration applications.

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