Studies have documented a link between distracted driving and diminished safety; however, an association between distracted driving and traffic congestion has not been investigated in depth. The present study examined the behavior of teens and young adults operating a driving simulator while engaged in various distractions (i.e., cell phone, texting, and undistracted) and driving conditions (i.e., free flow, stable flow, and oversaturation). Seventy five participants 16 to 25 years of age (split into 2 groups: novice drivers and young adults) drove a STISIM simulator three times, each time with one of three randomly presented distractions. Each drive was designed to represent daytime scenery on a 4 lane divided roadway and included three equal roadway portions representing Levels of Service (LOS) A, C, and E as defined in the 2000 Highway Capacity Manual. Participants also completed questionnaires documenting demographics and driving history. Both safety and traffic flow related driving outcomes were considered. A Repeated Measures Multivariate Analysis of Variance was employed to analyze continuous outcome variables and a Generalized Estimate Equation (GEE) poisson model was used to analyze count variables. Results revealed that, in general more lane deviations and crashes occurred during texting. Distraction (in most cases, text messaging) had a significantly negative impact on traffic flow, such that participants exhibited greater fluctuation in speed, changed lanes significantly fewer times, and took longer to complete the scenario. In turn, more simulated vehicles passed the participant drivers while they were texting or talking on a cell phone than while undistracted. The results indicate that distracted driving, particularly texting, may lead to reduced safety and traffic flow, thus having a negative impact on traffic operations. No significant differences were detected between age groups, suggesting that all drivers, regardless of age, may drive in a manner that impacts safety and traffic flow negatively when distracted.

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The relationship between persistent pain in spinal cord injury and medical-descriptive, demographic, psychological and familial-social data was studied. Multiple linear regression and discriminant analysis were used to predict (1) presence or absence of pain; (2) severity of pain; (3) time post-injury onset of pain; (4) whether or not pain interfered with activities of daily living. The best combinations of predictor variables accounted for only 15 and 19% of the dependent measures pain vs. no-pain and onset of pain, respectively. The best combinations of predictor variables accounted for 43 and 44%, respectively of the dependent measures severity of pain and whether or not pain interfered with activities of daily living. Higher levels of subjective pain were associated with greater age, higher verbal intelligence, higher levels of anxiety and a more negative psycho-social situation. Persons who reported pain interfering with activities of daily living were more likely to be older, of higher intelligence, more depressed, clinically rated as experiencing greater levels of distress and immersed in a more negative psycho-social environment. The importance of psycho-social variables in the understanding of persistent spinal cord injury pain and the need for prospective studies along these lines are demonstrated.

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Incidence and prevalenceThe incidence of spinal cord injury (SCI) varies according to source, however, reports considered to be most accurate indicate that the annual rate is between 30·0 and 32·1 new spinal cord injuries per million persons at risk in the U.S.A. (DeVivo et al., 1980; Kraus et al., 1975). DeVivo, et al. (1980), used the mathematical relationship between incidence and duration to re-estimate the prevalence of SCI, calculating the rate to be approximately 906 per million.This figure is nearly 50° () greater than that estimated by Kurtzke (1975) who based his calculations on the length of median post-injury survival; a less precise statistic in light of that which is known today. Age, sex and raceIn the U.S.A., SCIs occur most frequently in persons between 15 and 20 years of age. According to the National SCI Database maintained by the Department of Rehabilitation Medicine at the University of Alabama at Birmingham, the mean age at injury is 29·7 years, the median age is 25 years and the mode (i.e. the most frequent age at injury) is 19 years (Stover and Fine, 1986). Reported differences in age distribution are believed to reflect a myriad of non-comparable data collection strategies. The National SCI Database confirms that SCI occurs more frequently among males than among females (a 4: 1 ratio) and that the average, annual race-specific incidence rates for SCI are slightly higher for blacks than whites, a finding consistent with the higher accidental death rate observed among blacks (Accident Facts, 1983). EtiologyA review of the 10 000 + cases documented in the National SCI database con firms that in the U.S.A., as in virtually all other industrialised countries, most spinal cord injuries result from motor vehicle crashes (47·7%) followed by falls (20·8° 0)' acts of violence-gunshot wounds and stabbings (14·6%) and sporting-