Increasing the rate of presentation and use of signals in elementary classroom teachers.

Two issues relevant to competency-based teacher training were investigated-the specification of acceptable implementation levels for validated techniques and the necessity and feasibility of providing training on those techniques. First, a descriptive study was conducted to collect data on two direct-instruction teaching techniques-rate of presentation and signalling-that have been demonstrated to be functionally related to child performance in earlier studies. Data collected on 13 teachers, who received intensive preservice and inservice training, were then used as a standard for comparison in a multiple-baseline design across three untrained teachers to evaluate the effects of training on the two techniques. The experimental study served to determine whether training on the two techniques was necessary; and, if training was necessary, whether a training package, including supervised practice, unsupervised practice, and self-critique, would result in adequate implementation levels for the two techniques. Low implementation levels during baseline for three untrained teachers indicated that training was necessary. With training, all teachers increased their levels of appropriately signalling pupil responses and accelerated their rates of presentation well above the levels of the comparison standard. Observations made one week and again four weeks after training ended showed that performance levels achieved during training were maintained.

Effect of sorbitol on interaction of phenolic preservatives with polysorbate 80.

The effect of sorbital on the binding of several commonly used phenolic preservatives (i.e., p-hydroxybenzoic acid, methylparaben, ethylparaben, and propylparaben) with the nonionic surfactant polysorbate 80 was investigated using an equilibrium dialysis technique. The binding data were expressed in the form of Scatchard plots utilizing a modified form of the Scatchard equation. The data analysis indicated that all four phenolic preservatives were bound to two distinct loci within the polysorbate micelle; one exhibited a high affinity and a low capacity for the preservative molecules, while the other appeared to have a near-zero affinity but an almost infinite binding capacity. The high affinity site was assumed to be located near the junction of the hydrocarbon core with the polyoxyethylene region of the micelle. The interaction of the preservatives with the second class of sites apparently involved a non-specific and nonsaturable partitioning of the preservative molecules into the polyoxyethylene region of the micelle. Sorbitol was ineffective in displacing significant amounts of bound preservative from either binding site, presumably because it was too polar to partition into the micelle sufficiently to displace bound preservative.