Improving traffic safety: conceptual considerations for successful action.

INTRODUCTION: In the early stages of motorization, it did not take rigorous scientific research to achieve major improvements in traffic safety. Instead, early traffic-safety countermeasures were often based exclusively on common sense. Since then, scientific research has gradually increased in importance as the basis for developing successful interventions. This shift was not made by choice but mostly by necessity: many of the "easy" problems have already been addressed, and the remaining problems are generally too complex for an approach based solely on common sense. Fortunately, our understanding of the complexities involved in traffic safety has recently made major gains, and common sense can now be supplemented, to some degree, by valid technical analysis. APPROACH: This article discusses major conceptual issues that should be considered in guiding the future development of effective, science-based traffic-safety countermeasures. IMPACT ON INDUSTRY: After briefly discussing the conceptual issues, the article offers a list of implications for action.

Discrepancies between intraocular lens implant power prediction formulas in pediatric patients.

PURPOSE: The SRK II, SRK/T, Holladay I, and Hoffer Q intraocular lens power prediction formulas have been claimed to be interchangeable in their predicted postoperative refractive outcome among pediatric patients. In this study, we evaluated this clinical perception. DESIGN: Mathematical analysis. METHODS: Analytical prediction of implant power using keratometry values up to 55 diopters and axial length values as short as 16 mm was performed for 2 different refractive goals using the optimized intraocular lens constants for the SRK II, SRK/T, Holladay I, Hoffer Q, and Haigis formulas. Comparison graphs for the predicted implant power of each formula were constructed and differences between predicted results of the formulas were plotted. MAIN OUTCOME MEASURE: Predicted implant power. RESULTS: Significant differences in intraocular lens power prediction were found among the Hoffer Q, Holladay I, and SRK II formulas in the pediatric range of axial length and keratometry values. The Holladay I and Haigis formulas were found to be similar in their intraocular lens power prediction. The SRK/T was comparable with the Holladay I and Haigis formulas, but still differed in the high keratometry values. CONCLUSIONS: This analysis demonstrates differences in the intraocular lens power prediction among commonly used formulas for axial length and keratometry values in the pediatric range. It is unclear under what circumstances each of these formulas may be preferred in the pediatric population.

Road safety in China: analysis of current challenges.

INTRODUCTION: China has the world's largest population, and is the second largest automobile market. China's economy is booming, resulting in a rapid increase in both the road infrastructure and access to private vehicles. Along with economic growth, the ownership of motorized vehicles has almost quadrupled in the past 10years, from 42.2million in 1997 to 159.7million in 2007. However, at the same time, China also has a very high number of road fatalities compared to other countries, with about 100,000 reported fatalities each year. METHOD: This study analyzes the Chinese road-fatality situation to identify areas in which the total harm caused by crashes can be substantially and readily reduced. It provides a comprehensive analysis of the current road-fatality situation in China using conventional indices and the likely future trends. RESULTS: Four areas were identified in which countermeasures have the most potential to substantially reduce fatalities in China: pedestrians and other non-motorists, nighttime driving, vehicle passengers, and motorcycles. CONCLUSION: While China faces unprecedented road safety issues, this report identifies major areas in which there are opportunities to greatly reduce total harm.

Warning reliability and driver performance in naturalistic driving.

OBJECTIVE: This study examines how naturalistic driving performance is influenced by the perceived reliability of an in-vehicle warning system using a unique measure of perceived reliability. BACKGROUND: Prior studies of warning reliability conducted in simulator and test-track experiments demonstrate that the objective reliability of a warning can influence a driver's responsiveness to that warning. METHODS: Driver responses to lateral drift warnings (LDWs) were examined to determine if the latency to initiate a corrective steering response was related to the subjective reliability of prior system performance. An operational definition of subjective reliability was developed based on measures of the proportion of LDWs responded to by a steering correction in the preceding 24-hr period - the day proportion. Age, gender, weather condition, light level, road class, weekday status, and day proportion were used to model correction latency in a linear model. RESULTS: A main effect of day proportion was found, suggesting that reaction time to respond decreases by about 375 ms as the day proportion increases from 0 to 1. CONCLUSION: The study illustrates a method of quantifying subjective reliability and performance using naturalistic data. The results suggest that latency to make a steering correction is inversely related to the perceived reliability of the warning system in the 24 hr preceding the warning. APPLICATION: The results have direct application to the method of assessing the efficacy of in-vehicle collision warning systems, suggesting that use of a perceived reliability measure may better predict a driver's disposition to respond to a warning.

Effect of axial length and keratometry measurement error on intraocular lens implant power prediction formulas in pediatric patients.

PURPOSE: To examine the relationship between axial length and keratometry measurement errors and intraocular lens (IOL) power calculations for pediatric eyes. METHODS: The sensitivity of IOL power calculation to errors in axial length and keratometry measurements was computed as a function of axial length and keratometry for the SRK II, Hoffer Q, Holladay I, SRK/T, and Haigis formulas. RESULTS: The sensitivity of the IOL power calculation to an axial length measurement error is increased at 4 to 14 D/mm error in axial length in children compared with 3 to 4 D/mm error in axial length in adults. The error in calculation is 0.8 to 1.3 D/D error in keratometry measurement for both children and adults. CONCLUSIONS: Axial length measurement errors in pediatric eyes may lead to large errors in IOL power calculations.

Address entry while driving: speech recognition versus a touch-screen keyboard.

A driving simulator experiment was conducted to determine the effects of entering addresses into a navigation system during driving. Participants drove on roads of varying visual demand while entering addresses. Three address entry methods were explored: word-based speech recognition, character-based speech recognition, and typing on a touch-screen keyboard. For each method, vehicle control and task measures, glance timing, and subjective ratings were examined. During driving, word-based speech recognition yielded the shortest total task time (15.3 s), followed by character-based speech recognition (41.0 s) and touch-screen keyboard (86.0 s). The standard deviation of lateral position when performing keyboard entry (0.21 m) was 60% higher than that for all other address entry methods (0.13 m). Degradation of vehicle control associated with address entry using a touch screen suggests that the use of speech recognition is favorable. Speech recognition systems with visual feedback, however, even with excellent accuracy, are not without performance consequences. Applications of this research include the design of in-vehicle navigation systems as well as other systems requiring significant driver input, such as E-mail, the Internet, and text messaging.