Proper securement of wheelchairs in motor vehicles is vital to providing wheelchair users an adequate level of safety in a crash. Thus far, wheelchair tiedown and occupant restraint systems (WTORS) loading has mostly been examined under frontal impact conditions. Because of the inherent crash dynamic differences, rear-impact loading of WTORS is expected to differ greatly. In this study, three identical, reinforced, manual, folding, X-braced ANSI/RESNA WC19 wheelchairs were subjected to an International Organization for Standardization-proposed rear-impact crash pulse. WTORS loads (front tiedowns, rear tiedowns, lap belt, and shoulder belt) were measured and compared with frontal impact WTORS loading. Rear impact produced substantially higher loads (up to 7,851 N) in the front tiedowns than frontal impact. The rear tiedowns experienced relatively negligible loading (up to 257 N) in rear impact, while rear-impact dynamics caused the lap belt (maximum load of 1,865 N) to be loaded substantially more than the shoulder belt (maximum load of 68 N). Considering differences in frontal and rear impact WTORS loading is important to proper WTORS design and, thus, protection of wheelchair-seated occupants subjected to rear-impact events.

Optical coherence tomography (OCT) is rapidly becoming the method of choice for assessing arterial wall pathology in vivo. Atherosclerotic plaques can be diagnosed with high accuracy, including measurement of the thickness of fibrous caps, enabling an assessment of the risk of rupture. While the OCT image presents morphological information in highly resolved detail, it relies on interpretation of the images by trained readers for the identification of vessel wall components and tissue type. We present a framework to enable systematic and automatic classification of atherosclerotic plaque constituents, based on the optical attenuation coefficient mu(t) of the tissue. OCT images of 65 coronary artery segments in vitro, obtained from 14 vessels harvested at autopsy, are analyzed and correlated with histology. Vessel wall components can be distinguished based on their optical properties: necrotic core and macrophage infiltration exhibit strong attenuation, mu(t)>or=10 mm(-1), while calcific and fibrous tissue have a lower mu(t) approximately 2-5mm(-1). The algorithm is successfully applied to OCT patient data, demonstrating that the analysis can be used in a clinical setting and assist diagnostics of vessel wall pathology.