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An optical system, similar in concept to a telecentric lens system, has been developed to decouple in-plane surface deformations from out-of-plane motions for magnified images of a specimen under loading. The key parameters of the optical system were identified and rigorous testing of a prototype system was completed. The range in system parameters that can be used to eliminate the effect of out-of-plane motion (ΔSo) when ΔSo is less than a pre-specified magnitude (β) was experimentally quantified. Using the test results, an optical system was designed, built and successfully tested. Images of two test specimens at various loads are obtained at magnifications ranging from 2X to 6X, after testing was performed to ensure that the specimens do not move out-of-plane more than β during the loading history. First, images of a specimen undergoing uniaxial loading are acquired. Next, images of a single edge cracked specimen under load are obtained. For both specimens, the in-plane surface displacement field is determined by using digital image correlation of image subsets. Displacement gradients on the surface are computed after smoothing the displacement data. It is shown that the optical system developed in this work can be combined with a digital correlation method to accurately quantify in-plane surface deformations independent of the out-of-plane motion for magnifications up to 6X. Similar considerations will allow one to use the methodology with larger or smaller magnification factors.

A new insect repellent, BayRepel, containing the active ingredient KBR 3023, was examined for repellent efficiency against the biting midge Culicoides impunctatus Goetghebuer. Assessments were made using landing rates on the forearms of five human subjects with two treatment concentrations of BayRepel and also an alternative repellent, Mosi-guard. BayRepel was found to significantly reduce landing rates for over 8 h, but with a significant reduction in efficiency at 2-4 h post-application. Increasing the dose of BayRepel led to a significantly greater protection at 8 h post-application, reducing landing rates by 75.8±8.5%. No significant differences were found in protection levels between individuals.

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