This investigation examined short-term changes in child and adult cyclists' gap decisions and movement timing in response to general and specific road-crossing experiences. Ten-and 12-yearolds and adults rode a bicycle through a virtual environment with 12 intersections. Participants faced continuous cross traffic and waited for gaps they judged were adequate for crossing. In the control condition, participants encountered randomly ordered gaps ranging from 1.5 to 5 s at all intersections. In the high-density condition, participants encountered high-density intersections sandwiched between sets of control intersections. These high-density intersections were designed to push participants toward taking tighter gaps. Participants in both conditions were more likely to accept 3.5, 4, 4.5, and 5 s gaps during the last than the first set of intersections, whereas participants in the high-density condition were also more likely to accept very tight 3 s gaps at the last than the first set of intersections. Moreover, individuals in the high-density condition who waited less and took shorter gaps during the middle intersections were also more likely to take very tight 3 s gaps during the last intersections. Ten-year-olds in both conditions had more time to spare when they cleared the path of the oncoming car at the last intersections, whereas 12-yearolds and adults showed no change in time to spare across intersections. Discussion focuses on linking short-term change in perceptual-motor functioning to longer-term perceptual-motor development.Keywords perceptual-motor development; perception-action coupling; road crossing; practice A fundamental problem confronting the developing perceptual-motor system is learning how to bring decisions and actions tightly in line with perceptual information. This ability to fine tune judgments and actions is important both for learning new perceptual-motor skills and for improving existing ones. Becoming a skilled pedestrian, for example, involves improved use of visual information to guide gap decisions and to time interceptive movements. Clearly, experience plays a critical role in producing these kinds of changes in perception-action tuning. Probably the most important aspect of this experience is repeated practice with performing perceptual-motor skills. But how does practice with performing a

Objectives Compared with unadjusted shock index (SI) (heart rate/systolic blood pressure), age-adjusted SI improves identification of negative outcomes after injury in pediatric patients. We aimed to further evaluate the utility of age-adjusted SI to predict negative outcomes in pediatric trauma. Methods We performed an analysis of patients younger than 15 years using the National Trauma Data Bank. Elevated SI was defined as high normal heart rate divided by low-normal blood pressure for age. Our primary outcome measure was mortality. Secondary outcomes included need for a blood transfusion, ventilation, any operating room/interventional radiology procedures, and intensive care unit stay. Multiple logistic regressions were performed. Results Twenty-eight thousand seven hundred forty-one cases met the study criteria. The overall mortality rate was 0.7%, and 1.7% had an elevated SI. Patients with an elevated SI were more likely (P < 0.001) to require blood transfusion, ventilation, an operating room/interventional radiology procedure, or an intensive care unit stay. An elevated SI was the strongest predictor for mortality (odds ratio [OR] 22.0) in pediatric trauma patients compared with hypotension (OR, 12.6) and tachycardia (OR, 2.6). Conclusions Elevated SI is an accurate and specific predictor of morbidity and mortality in pediatric trauma patients and is superior to tachycardia or hypotension alone for predicting mortality.

OBJECTIVES: To determine the prevalence of invasive bacterial infections (IBIs) and adverse events in afebrile infants with acute otitis media (AOM). METHODS: We conducted a 33-site cross-sectional study of afebrile infants ≤90 days of age with AOM seen in emergency departments from 2007 to 2017. Eligible infants were identified using emergency department diagnosis codes and confirmed by chart review. IBIs (bacteremia and meningitis) were determined by the growth of pathogenic bacteria in blood or cerebrospinal fluid (CSF) culture. Adverse events were defined as substantial complications resulting from or potentially associated with AOM. We used generalized linear mixed-effects models to identify factors associated with IBI diagnostic testing, controlling for site-level clustering effect. RESULTS: Of 5270 infants screened, 1637 met study criteria. None of the 278 (0%; 95% confidence interval [CI]: 0%–1.4%) infants with blood cultures had bacteremia; 0 of 102 (0%; 95% CI: 0%–3.6%) with CSF cultures had bacterial meningitis; 2 of 645 (0.3%; 95% CI: 0.1%–1.1%) infants with 30-day follow-up had adverse events, including lymphadenitis (1) and culture-negative sepsis (1). Diagnostic testing for IBI varied across sites and by age; overall, 278 (17.0%) had blood cultures, and 102 (6.2%) had CSF cultures obtained. Compared with infants 0 to 28 days old, older infants were less likely to have blood cultures (P &lt; .001) or CSF cultures (P &lt; .001) obtained. CONCLUSION: Afebrile infants with clinician-diagnosed AOM have a low prevalence of IBIs and adverse events; therefore, outpatient management without diagnostic testing may be reasonable.

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