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Radial frequency (RF) contours can be used to represent the boundaries of natural objects, making them a useful stimulus with which to study shape processing. The current study used these contours to investigate whether luminance- and contrast-defined shape cues are combined in the detection of globally processed contours. A set of three experiments are(More)
We report on the toxicity of ZnO nanoparticles (NPs) to gram-negative and gram-positive bacterial systems, Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), and primary human immune cells. ZnO NP (~13 nm) showed complete inhibition of E. coli growth at concentrations 3.4 mM, whereas growth of S. aureus was completely inhibited for 1 mM.(More)
Adaptation to prevailing stimuli is a ubiquitous property of the visual system that optimizes its dynamic range. The perceived difference in orientation of successively presented lines of similar orientation is exaggerated and the perceived shape of an object is influenced by previously experienced shapes. Change in perceived shape is assumed to arise(More)
The study of shape processing in the human visual system has frequently employed radial frequency (RF) patterns as conveniently manipulable stimuli. This study uses an adaptation paradigm to investigate how local shape information is sampled in the processing of RF contour shapes. Experiment 1 measured thresholds for detecting a fixed mean radius RF contour(More)
Radial Frequency (RF) contours provide a unifying system to represent familiar shapes, such as triangles (RF3), squares (RF4) and pentagons (RF5), but it is not clear whether these sorts of shapes are detected by separate RF-tuned processes, or instead by a common shape mechanism. It has been suggested that multiple mechanisms are responsible for the(More)
Previous research has shown that the mechanisms that process curved contours are selective for low-level attributes such as luminance contrast polarity and luminance spatial-frequency, while those that process curvature-defined global shapes are not. While these findings are consistent with the view that higher stages of object processing are relatively(More)
Autosomal dominant frontotemporal dementia (FTD) due to mutations in the MAPT gene is referred to as FTD with parkinsonism linked to chromosome 17 with tau pathology (FTDP-17T). Typically the disease begins in the sixth decade of life. We report a novel exon 12 mutation in MAPT (S356T), in a family with an exceptionally early age at onset (27 and 29 years),(More)
Human observers can rapidly judge the number of items in a scene. This ability is underpinned by specific mechanisms encoding number or density. We investigated whether judgments of number and density are biased by a change in volume, as they are by a change in area. Stimuli were constructed using nonoverlapping black and white luminance-defined dots. An(More)
Radial frequency (RF) patterns have been used to study the processes involved in shape perception. The psychophysical literature suggests that there are distinct global and local shape detection processes for low and high radial frequency patterns, but this has not been tested in a combined contour pattern, such as would be needed to describe the contours(More)
Research suggests that detection of low-frequency radial frequency (RF) patterns involves global shape processing and that points of maximum curvature (corners) contribute more than points of minimum curvature (sides). However, this has only been tested with stimuli presented at the threshold of discriminability from a circle. We used RF pattern adaptation(More)