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Biomedical subjects

E P Hall

Publications and source records attributed to E P Hall.

3 recordsLinked to original sources

Analyzing components of work samples to evaluate performance.

A method is described in which work sample data were analyzed to reveal how aircraft maintenance technicians differed in troubleshooting performance after a training intervention. During the training phase of the study, approximately half the technicians received troubleshooting instruction from an intelligent tutoring system, and the remaining technicians received informal on-the-job training. Data from work samples, in which technicians verbally isolated simulated equipment failures, were collected from both groups before and after the training. The work sample data were then examined by subject matter experts who scored performance for overall proficiency and noted specific violations of good troubleshooting practice. These violations provided the basis for the components of performance examined in the work sample data. The results of this componential analysis allow more specific conclusions to be drawn regarding the effectiveness of the training intervention by revealing how the tutoring system improved technicians' troubleshooting (e.g., tutored technicians were more likely than untutored technicians to test components thoroughly to ensure they were faulty before replacing them).

Aerospace Medicine↗

Regulation of rat IgE responses by immune complexes.

The immunizing ability of immune complexes preformed between EA and EA-hyperimmune serum was investigated in adult rats. After immunization with complexes at equivalence, the pattern of suppressed IgE responsiveness was similar to that induced when a small volume of immune serum accompanied routine immunization. We have suggested that the underlying principle is the same, and that the IgE response can be regulated by immune complexes. The ability to influence an ongoing IgE response was determined by treating with complexes at various times after immunization. While the primary IgE levels were differentially affected, the most consistent suppression was seen at the secondary stage. The data suggest that a stage of B-cell differentiation has been interrupted and that IgE antibody-producing cells have been prevented from developing.

Albumins↗

Suppression of IgE responses by hyperimmune serum in rats.

Recent work has shown that a relatively long-lasting suppression of egg albumin (EA)-specific IgE responsiveness occurs in the progeny of EA-immunized mother rats. This phenomenon can be duplicated by a course of EA-immune serum injections given to the neonatal progeny of normal mothers, and antigen-specific IgG was found to be the effective mediator. In order to elucidate further the mechanism of this selective suppression, the capacity of immune serum to suppress IgE responsiveness in adults was investigated. Pretreatment of adults with hyperimmune serum 3 weeks in advance of immunization was as effective as when the animals were neonatally treated. The possibility that the mediator responsible is the very small amount of EA-specific IgG remaining at the time of immunization was tested by injecting a small volume of immune serum simultaneously with immunization. This treatment also suppressed IgE responsiveness. The possibility that low levels of EA-specific antibody form complexes with the immunizing antigen is discussed.

Age Factors↗