Donald D. Duncan

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The ultimate objective of laser speckle flowmetry (and a host of specific implementations such as laser speckle contrast analysis, LASCA or LSCA; laser speckle spatial contrast analysis, LSSCA; laser speckle temporal contrast analysis, LSTCA; etc.) is to infer flow velocity from the observed speckle contrast. Despite numerous demonstrations over the past 25(More)
When laser light illuminates a diffuse object, it produces a random interference effect known as a speckle pattern. If there is movement in the object, the speckles fluctuate in intensity. These fluctuations can provide information about the movement. A simple way of accessing this information is to image the speckle pattern with an exposure time longer(More)
PURPOSE To determine the visual and other factors that predict stopping or restricting driving in older drivers. METHODS A group of 1425 licensed drivers aged 67 to 87 years, who were residents of greater Salisbury, participated. At 1 year after enrollment, this group was categorized into those who had stopped driving, drove only within their(More)
ree-space optical communications systems for deep space and near-terrestrial space environments are now poised for deployment aboard spacecraft. Although many fundamental technical problems have been solved, detailed engineering development is still needed to make space-worthy optical communications terminals. Very high bandwidths (10 Gbps or higher) and fi(More)
PURPOSE A classical twin study was performed to establish the relative importance of genes and environment in cortical cataract. METHODS Five hundred six pairs of unselected female twin volunteers (226 monozygotic and 280 dizygotic) with a mean age of 62 years (range, 49-79 years) were examined. Cortical cataract was assessed using the slit-lamp-based(More)
The purpose of this study was to determine racial differences in the prevalence of different types of lens opacities and cataract surgery. Between 1993 and 1995, the Salisbury Eye Evaluation (SEE) Project enrolled a representative sample of 2,520 community-dwelling persons aged 65-84 years in Salisbury, Maryland, 26.4% of whom were African-American.(More)
Through a series of simulations and experiments, we demonstrate that the frequently cited criterion of matching speckle size to detector element (pixel) size in laser speckle contrast imaging (LSCI) has the detrimental effect of reducing the contrast and thereby decreasing the variation in the laser speckle contrast image. Unlike quasi-elastic light(More)
BACKGROUND Despite sensational news reports, few studies have quantified the rates of poor driving performance among older drivers and the predictors of poor performance. We determined the rate of running red traffic lights among older drivers and the relationship of failure to stop to measures of vision and cognition. METHODS Multiple measures of vision(More)
PURPOSE To observe the spatial distribution of households with high loads of ocular chlamydia infection in children, before and after mass treatment with azithromycin to determine whether there exists spatial clustering of households with high loads of infection and the spatial scale of the clustering. METHODS All residents of a village in Tanzania were(More)
Our purpose was to determine visual and cognitive predictors for older drivers' failure to stop at stop signs. 1425 drivers aged between ages 67 and 87 residing in Salisbury Maryland were enrolled in a longitudinal study of driving. At baseline, the participants were administered a battery of vision and cognition tests, and demographic and health(More)