Relative stabilities of nitrenium ions derived from heterocyclic amine food carcinogens: relationship to mutagenicity.

The bacterial mutagenicities of a wide variety of complex heteroaromatic amine mutagens and carcinogens present in cooked foods are approximately related to the stabilities of the corresponding nitrenium ions through equations of the kind: log(m) = a delta delta H + b. The stabilities of the nitrenium ions (delta delta H) were computed using the semiempirical AM1 molecular orbital procedure. Parallel calculations of the energies, charge distributions and geometries of simple model compounds provides a qualitative framework within which the stabilities of the nitrenium ions derived from the food carcinogens can be easily understood.

The effects of different levels of task complexity on three vocal measures.

Interactive voice query and control systems are being considered as an alternative method of interfacing pilots with aircraft systems in high performance aviation environments. Before engineers integrate interactive voice systems into aircraft, knowledge is needed concerning what types of vocal changes, if any, are likely to occur as a result of environmental and task-induced stress. Recordings of the vocal utterances of 20 subjects, obtained as the subjects performed psychomotor and dichotic listening tasks, were subjected to acoustical analyses to evaluate the effects of task complexity on three measures: fundamental frequency (fo), peak amplitude (intensity), and word duration. The analyses revealed significant increases in fo (p less than 0.05) and amplitude (p less than 0.01) and a significant decrease in word duration (p less than 0.01) as a function of increased task complexity. These findings suggest that task-induced vocal changes must be considered in the design of voice recognition systems for use in complex, high performance aviation environments.

Review of psychomotor skills in pilot selection research of the U.S. military services.

This review provides an historical perspective of the use of psychomotor, perceptual--cognitive paper-and-pencil, and automated tests for the selection of pilot trainees by the U.S. military services. Automated versions of vintage psychomotor tests (developed in the 1930s and 1940s) seem to be as predictive of military pilot/aviator performance today as in the past. The psychomotor tests receiving the most attention today are the Complex Coordination and Two-Hand Coordination tests originally developed by Mashburn and colleagues [correction of colleges] before World War II (Mashburn, 1934). These tests were significant predictors of Air Force and Navy pass--fail criteria in the past, and automated versions are similarly predictive today. The U.S. Army and Air Force are now using a combination of paper-and-pencil and automated psychomotor--cognitive tests for initial selection (Air Force) or helicopter assignment (Army). It appears that the Navy is considering the use of automated cognitive and psychomotor tests in a selection battery of the future.