Cigarette promotional items in public schools.

OBJECTIVES: To assess the prevalence of ownership of cigarette promotional items (CPIs) by rural northern New England students and to examine the association between CPI ownership and smoking behavior. DESIGN AND SETTING: Voluntary, self-administered survey of 1265 sixth- through 12th-grade students representing 79% to 95% of all students attending 5 rural New Hampshire and Vermont public schools in October 1996. We examined the association between ownership of a CPI and smoking behavior through regression models and conducted a sensitivity analysis on the findings. MAIN OUTCOME MEASURES: Adjusted odds of being a smoker (lifetime use of > or = 100 cigarettes) and, among never smokers and experimental smokers, adjusted cumulative odds of having higher levels of smoking uptake given CPI ownership. RESULTS: One third of students owned a CPI. Prevalence of ownership did not vary by grade or sex, but was higher among poor-to-average school performers (45.0% vs 21.0% for excellent school performers, P < .001) and children whose friends and family members smoked (43.4% vs 13.8% for students with no family members or friends smoking, P < .001). Cigarette promotional items included articles of clothing (T-shirts, hats, backpacks, and jackets), smoking paraphernalia (lighters and ashtrays), camping gear, and electronics. More than half of CPIs (58.2%) bore the Marlboro logo, and almost one third (31.7%) bore the Camel logo. These items were obtained directly from catalogs or vendors 22.4% of the time. Whereas only 4.5% of students reported bringing a CPI to school with them the day of the survey, 44.5% reported seeing such an item at school the day of the survey. After controlling for confounding factors, such as having friends who smoke, students who owned CPIs were 4.1 times more likely to be smokers than those who did not own CPIs (95% confidence interval [CI], 3.1-5.5). Never and experimental smokers (n = 1008) who owned CPIs were more likely to be in a higher category on the smoking uptake index in grades 6 (cumulative odds ratio [OR = 5.7, 95% CI, 1.9-16.8), 7 (OR = 1.8, 95% CI, 0.9-3.7), 8 (OR = 2.3, 95% CI, 1.1-4.8), and 9 (OR = 2.1, 95% CI, 1.1-3.9), periods when children are most vulnerable to initiating cigarette use. A sensitivity analysis indicated that an unmeasured confounder of CPI ownership and smoking was unlikely to alter our conclusions. CONCLUSIONS: Cigarette promotional items are owned by one third of students in these rural northern New England schools. These items are highly visible in the public school setting, and their ownership is strongly associated with initiation and maintenance of smoking behavior. These data lend support to a ban on CPIs to be included in US Food and Drug Administration regulations to prevent tobacco use among US youth.

Safety and efficacy evaluation of a fitness club weight-loss program.

It is well documented that excess weight is a major risk factor for many chronic diseases, and, despite considerable expenditure of time, money, and effort, little or no progress has been made in reversing the trend toward increased weight. Although fitness and athletic clubs offer one potential for tackling this problem, few provide information about the efficacy of their weight-loss programs. There is general agreement that an efficacious weight-loss program should reduce body fat, maintain or increase fat-free mass (FFM), and lower total and low-density lipoprotein (LDL) cholesterol. This study was designed to compare changes in body composition and serum cholesterol associated with participation in a fitness club program (EXP) versus changes that occurred when participants pursued a program of their own choosing (CTL). The EXP group participated in the Bally's Total Fitness program that included exercise, behavior modification, and dietary supplements. Although only small differences in body weight were noted between groups, participation in the EXP program led to significant (sixfold) reductions in fat mass, increases in FFM, and improvements in body composition. These data highlight the importance of using measures of body composition rather than scale weight in evaluating the efficacy of weight-loss programs. Additionally, the EXP group achieved significant reductions in total and LDL cholesterol, particularly among individuals with baseline total cholesterol levels above 200 micrograms/dL. It is also worth noting that respective cholesterol levels were maintained for participants with total cholesterol levels between 150 and 199 micrograms/dL and were increased for those with levels at or below 150 micrograms/dL.

Numerical simulations of the Richtmyer-Meshkov instability in solid-vacuum interfaces using calibrated plasticity laws.

The Richtmyer-Meshkov instability of interfaces separating elastic-plastic materials from vacuum (heavy-light configuration) is studied by means of computational techniques. A fully Eulerian multimaterial algorithm that solves consistently the Euler equations and the time evolution of the deformations in the material is applied to three distinct materials (copper, aluminum, and stainless steel). If a perfectly plastic constitutive relation is considered, an empirical law is computed that relates the long-term perturbation amplitude of the interface, its maximum growth rate, the initial density, and the yield stress of the material. It is shown that this linear relation can be extended to materials that follow more complex plastic behavior which can account for rate dependency, hardening, and thermal softening, and to situations in which small-perturbation theory is no longer valid. In effect, the yield stress computed from measurements of the long-term amplitude and maximum growth rate closely matches the von Mises stress found at the interface of solid materials for a wide range of cases with different initial parameters.

Linearized Richtmyer-Meshkov flow analysis for impulsively accelerated incompressible solids.

We present an analytical study of the linearized impulsive Richtmyer-Meshkov flow for incompressible elastic solids. Seminumerical prior investigations of a related shock-driven compressible elastic problem suggest that the interface amplitude remains bounded in time, in contrast to the unstable behavior found for gases. Our approach considers a base unperturbed flow and a linearization of the conservation equations around the base solution. The resulting initial and boundary value problem is solved using Laplace transform techniques. Analysis of the singularities of the resultant function in the Laplace domain allows us to perform a parametric study of the behavior of the interface in time. We identify two differentiated long-term patterns for the interface, which depends on the material properties: standing wave and oscillating decay. Finally, we present results for the vorticity distribution, which show that the shear stiffness of the solids is responsible both for the stabilization of the interface, and also for the period of the interface oscillations. Comparisons with previous results are discussed.

Stability of an impulsively accelerated density interface in magnetohydrodynamics.

In the framework of ideal incompressible magnetohydrodynamics, we examine the stability of an impulsively accelerated, sinusoidally perturbed density interface in the presence of a magnetic field that is parallel to the acceleration. This is accomplished by analytically solving the linearized initial value problem, which is a model for the Richtmyer-Meshkov instability. We find that the initial growth rate of the interface is unaffected by the presence of a magnetic field, but for a finite magnetic field the interface amplitude asymptotes to a constant value. Thus the instability of the interface is suppressed. The interface behavior from the analytical solution is compared to the results of both linearized and nonlinear compressible numerical simulations.