Optical coherence tomography (OCT) has long been used as a diagnostic tool in the field of ophthalmology. The ability to observe microstructural changes in the tissues of the eye has proved very effective in diagnosing ocular disease. However, this technology has yet to be introduced into the primary care office, where indications of disease are first encountered. We have developed a portable, handheld imaging probe for use in the primary care setting and evaluated its tissue site accessibility, ability to observe diseased tissue, and screening capabilities in in vivo human patients, particularly for pathologies related to the eye, ear and skin. Various stages of diabetic retinopathy were investigated using the handheld probe and early-stage diabetic retinopathy was flagged as abnormal from the OCT images. At such early stages of disease, it is difficult to observe abnormalities with the limited tools that are currently available to primary care physicians. These results indicate that OCT shows promise to transform from being a diagnostic technology in the medical and surgical specialities to a screening technology in the primary care office and at the front-line of healthcare.
In vivo
cross-sectional images of four examples of common pathologies in humans encountered by a primary care physician. All images were taken using a novel handheld OCT imaging probe. (A) Human cornea after LASIK surgery. (B) Advanced diabetic retinopathy. (C) Tympanic membrane with accompanying biofilm. (D) Skin abscess showing layer separation and fluid-filled pockets.
An acoustic tracking system is described that has been used to track Weddell seals inAntarctica and ringed and spotted seals in the arctic. The seals are released with a small, depth-modulated acoustic transmitter attached. They are tracked in real time based on the time difference of arrival at four hydrophones of the pulse from the acoustic transmitter. Working ranges are approximately those predicted by acoustic equations. Closed-form solutions of the tracking algorithm allow rapid calculation of position. The effect of different array geometries on accuracy of tracking is explored analytically.
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