Christopher A. Clark

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PURPOSE Peripheral refractive error degrades the quality of retinal images and has been hypothesized to be a stimulus for the development of refractive error. The purpose of this study was to investigate the changes in refractive error across the horizontal visual field produced by contact lenses (CLs) and to quantify the effect of CLs on peripheral image(More)
We used a confocal adaptive optics scanning laser ophthalmoscope (AOSLO) to image the retina of subjects with non-proliferative diabetic retinopathy (NPDR). To improve visualization of different retinal features, the size and alignment of the confocal aperture were varied. The inner retinal layers contained clearly visualized retinal vessels. In diabetic(More)
PURPOSE We evaluated the relationship between cone photoreceptor packing density and outer nuclear layer (ONL) thickness within the central 15 degrees. METHODS Individual differences for healthy subjects in cone packing density and ONL thickness were examined in 8 younger and 8 older subjects, mean age 27.2 versus 56.2 years. Cone packing density was(More)
DiVusion tensor imaging (DTI) fully characterises water molecule mobility in vivo, allowing an exploration of fibre tract integrity and orientation in the human brain. Using DTI this study demonstrates reduced fibre coherence (anisotropy) associated with cerebral infarction and in the corticospinal tract remote from the lesion, in five patients 2 to 6(More)
Strains of the sweet potato soil rot pathogen Streptomyces ipomoeae had previously been divided into three groups based on their ability to inhibit one another during pairwise cocultivation. While group I strains are not antagonistic to members of the other groups, group II and group III strains produce separate substances that are inhibitory to strains(More)
Streptomyces ipomoeae is the causal agent of Streptomyces soil rot of sweet potato, a disease marked by highly necrotic destruction of adventitious roots, including the development of necrotic lesions on the fleshy storage roots. Streptomyces potato scab pathogens produce a phytotoxin (thaxtomin A) that appears to facilitate their entrance into host plants.(More)
Introduction There have been few studies using diffusion MRI based tractography to look at the normal development of specific tracts during late childhood and adolescence. However, there is some evidence for the existence of relationships between diffusion parameters, especially fractional anisotropy (FA) and mean diffusivity (MD), and age or gender (e.g.(More)
Introduction This work describes, for the first time, a process for optimising both the standard Stejskal–Tanner (ST) diffusion MR sequence and the dual spin-echo (DSE) sequence, for the specific purpose of directly estimating axon radius or other microstructural properties of white matter. There has been considerable recent interest in the use of diffusion(More)