Effects of night-time bicycling visibility aids on vehicle passing distance.

Bicycling at night is dangerous, with vehicle passing distances being a key concern, given that the main cause of night-time bicycling fatalities is from motorists hitting bicyclists from behind. However, little is known about vehicle passing distances at night or how they are affected by bicyclist visibility. This study assessed the impact of different bicyclist visibility configurations on vehicle passing distances at night-time. Fourteen licenced drivers with normal vision (age 24.2 ±â€¯3.7 years) drove an experimental vehicle with low-beam headlights around a 1-km section of a closed-road circuit at night. Each lap involved passing two bicyclists displaying one of four visibility configurations: Control (red rear-facing light and reflector), Handlebars (control plus two red rear-facing lights on each handlebar), Helmet (control plus one red rear-facing light on the helmet), and Leg Retro-reflectors (control plus retro-reflective strips positioned on the knees and ankles). Participants were instructed to pass each bicyclist at a distance of 1-metre at a speed no greater than 50 km/hr, consistent with Queensland's Minimum Passing Distance rule. Participants completed eight laps, two for each configuration, in a randomised sequence. Passing distance was measured using a vehicle-mounted ultra-sonic sensor (ToughSonic14; Senix). Following each lap, participants rated the difficulty level in judging the 1-metre passing distance, as well as their estimated passing distance. Visibility configuration significantly affected passing distance (p = 0.001), with wider passing distances for the Handlebar configuration (1.54 ±â€¯0.62 m), followed by the Helmet (1.51 ±â€¯0.63 m), Leg Retro-reflectors (1.50 ±â€¯0.62 m) which were all significantly greater than the Control (1.42 ±â€¯0.57 m), but not significantly different from each other. There was also a significant effect of visibility configuration on difficulty rating (p = 0.035), with the Control rated as the most difficult, followed by Helmet, Handlebars and Leg Retro-reflectors. Overall, additional visibility aids resulted in wider vehicle passing distances, likely due to enhanced visual cues for drivers. The findings suggest that bicyclists should incorporate additional visibility aids to encourage safer passing distances of vehicles at night-time.

Solid or gaseous circulating brain emboli: are they separable by transcranial ultrasound?

High-intensity transient signals (HITS) detected by transcranial Doppler (TCD) ultrasound may correspond to artifacts or to microembolic signals, the latter being either solid or gaseous emboli. The goal of this study was to assess what can be achieved with an automatic signal processing system for artifact/microembolic signals and solid/gas differentiation in different clinical situations. The authors studied 3,428 HITS in vivo in a multicenter study, i.e., 1,608 artifacts in healthy subjects, 649 solid emboli in stroke patients with a carotid stenosis, and 1,171 gaseous emboli in stroke patients with patent foramen ovale. They worked with the dual-gate TCD combined to three types of statistical classifiers: binary decision trees (BDT), artificial neural networks (ANN), and support vector machines (SVM). The sensitivity and specificity to separate artifacts from microembolic signals by BDT reached was 94% and 97%, respectively. For the discrimination between solid and gaseous emboli, the classifier achieved a sensitivity and specificity of 81% and 81% for BDT, 84% and 84% for ANN, and 86% and 86% for SVM, respectively. The current results for artifact elimination and solid/gas differentiation are already useful to extract data for future prospective clinical studies.