Evaluating the Effectiveness of Child Safety Seats and Seat Belts in Protecting Children from Injury

Young children are required to use child safety seats, and the age threshold at which children can legally graduate to seat belts has steadily increased. This paper tests the relative effectiveness of child safety seats, lap-and-shoulder seat belts, and lap belts in preventing injuries among motor vehicle passengers aged 2-6. We analyze three large, representative samples of crashes reported to police, as well as linked hospital data. We find no apparent difference in the two most serious injury categories for children in child safety seats versus lap-and-shoulder belts. Child safety seats provide a statistically significant 25% reduction in the least serious injury category. Lap belts are somewhat less effective than the two other types of restraints, but far superior to riding unrestrained.

Non-linear analysis of electrocardiogram tracings in detection of occult coronary artery disease

The general problem of identifying significant characteristics of a system by analyzing the properties of a signal emitted by that system is common to many disciplines, biological as well as physical. In general, achievement of a satisfactory solution depends on the capability of assigning membership of candidate signals to one of a number of mutually exclusive categories: In this study, a new technique of processing the standard electrocardiograms from human subjects has been developed. This technique employs a set of non-linear transformations which enable the assignment of electrocardiograms into one of two Mutually exclusive categories. The first category is that of patients with occult coronary artery disease; the second category is that of subjects free from coronary artery disease. An introduction to the conventional means for assessing the standard electrocardiogram is presented, and the limitations noted. The new method is then presented which consists in large part of combining non-linear signal processing with a topological re-orientation of conventional cartesian coordinates to yield a multi-vector space which offers an optimum degree of visual perceptibility. Moreover, in this new domain, the transformed EKG tracings taken from subjects free from coronary artery disease inhabit a closed area, represented by the annular space bounded by two tangent circles. It is then shown that EKG tracings taken from subjects with occult coronary artery disease exhibit patterns which protrude beyond the circular boundaries. The mathematical transformations are shown to be non-linear and non-analytic in terms of satisfying the Cauchy-Riemann conditions. The assumptions and constraints of the transformations are explored and practical considerations are examined. Preliminary results obtained to date from over 100 medical cases are presented and analyzed. The tentative findings reveal a high degree of promise for the detection of asymptomatic coronary candidates well in advance of myocardial infarction. Finally, further applications to other medical areas are explored including a discussion of potential applicability to the fields of pharmacology and neurology

Micromechanical microphone using sideband modulation of nonlinear resonators

We report the successful detection of an audio signal via sideband modulation of a nonlinear piezoelectric micromechanical resonator. The 270$\times$96-$\mu$m resonator was shown to be reliable in audio detection for sound intensity levels as low as ambient room noise and to have an unamplified sensitivity of 23.9 $\mu$V/Pa. Such an approach may be adapted in acoustic sensors and microphones for consumer electronics or medical equipment such as hearing aids.Comment: 5 pages, 3 figure

Factors associated with excessive body fat in men and women: cross-sectional data from Black South Africans living in a rural community and an urban township

Objective To determine the factors associated with excessive body fat among black African men and women living in rural and urban communities of South Africa. METHODS: This is a cross-sectional analysis of data from the Prospective Urban and Rural Epidemiology (PURE) study, Cape Town, South Africa conducted in 2009/2010. The study sample included 1220 participants (77.2% women) aged 35-70 years, for whom anthropometric measurements were obtained and risk factors documented through face-to-face interviews using validated international PURE study protocols. Sex-specific logistic regression models were used to evaluate socio-demographic, lifestyle and psychological factors associated with three excessive body fat indicators, namely body mass index (BMI), waist circumference (WC) and body fat percent (BF%). RESULTS: The prevalence of excessive body fat based on BF%, WC and BMI cut-offs were 96.0%, 86.1%, and 81.6% for women respectively, and 62.2%, 25.9%, and 36.0% for men respectively. The significant odds of excessive body fat among the currently married compared to unmarried were 4.1 (95% CI: 1.3-12.5) for BF% and 1.9 (95% CI: 1.3-2.9) for BMI among women; and 4.9 (95% CI: 2.6-9.6), 3.2 (95% CI: 1.6-6.4) and 3.6 (95% CI: 1.9-6.8) for BF%, WC and BMI respectively among men. Age ≤50 years (compared to age >50 years) was inversely associated with excessive BF% in men and women, and less-than-a-college education was inversely associated with excessive BMI and WC in men. Tobacco smoking was inversely associated with all three excessive adiposity indicators in women but not in men. Unemployment, depression, and stress did not predict excessive body fat in men or women. CONCLUSION: The sex-differences in the socio-demographic and lifestyle factors associated with the high levels of excessive body fat in urban and rural women and men should be considered in packaging interventions to reduce obesity in these communities