False Response Rate Research Articles

Performance characteristics of a fish monitor for detection of toxic substances—I. Laboratory trials

The results of a laboratory assessment of the performance characteristics of a fish monitor, designed for the detection of toxic pollution events at drinking water intakes, are presented. The equipment assessed was developed by WRc in the U.K. and monitors significant changes in fish ventilation frequency as an indicator of the occurrence of a toxic pollutant. Rainbow trout ( Salmo gairdneri) were used in these trials being most commonly used in operation. Data from a trial period of 1 year were analysed to establish sensitivity to ten test substances and the estimated rate of false responses for the sensitivities quoted. Comparison with trout acute toxicity data (96 h LC 50) show responses at between 10 and 250% of the LC 50 with a response within 40 min. Comparison is also with 24 h SNARLs (suggested no adverse response levels) for humans where this is available. The monitor is capable of responding at concentrations below or close to these levels where the test substance could be expected to produce acute toxic symptoms, but the concentration of response may be considerably higher than the SNARL where toxic symptoms are of a chronic, long-term nature. The estimated rate of false responses for the monitor was between 1 in 3 and 1 in 5 months.

Differential light threshold in automated static perimetry. Factors influencing short-term fluctuation.

The scatter of the differential light threshold observed during a single visual field test is called the short-term fluctuation. A number of factors that may influence the magnitude of the short-term fluctuation were studied. The main factor was the level of the differential light sensitivity itself, followed by the rate of false responses in the catch trials. The pupil size was only notable in patients with glaucoma, while age as well as the mean reaction time did not appear to be notable. The short-term fluctuation is not dependent on the location in the visual field up to 27 degrees of eccentricity degrees tested in normal subjects and patients suspected of having glaucoma, but there is a slight tendency in patients with glaucoma for a larger short-term fluctuation in the upper half of the visual field.