Lattice refinement strategies.

This article quantitatively reconciles crystallographic and mechanics approaches to lattice refinement as part of X-ray diffraction procedures. The equivalence between the refinement based on unit-cell parameters to that based on a lattice deformation tensor is established from a fixed reference configuration. Justification for the small strain assumption, commonly employed in X-ray diffraction based stress analysis, is also derived. It is shown that relations based on infinitesimal strains are correct to within an error of quadratic order in strain. This error may be important to consider for high-precision or high-strain experiments. It is hoped that these results are of use for facilitating communication and collaboration between crystallography and experimental mechanics communities, for studies where X-ray diffraction data are the fundamental measurement.

Engaging youth in learning about healthful eating and active living: an evaluation of Educational Theater Programs.

OBJECTIVE: To compare knowledge gains and knowledge retention of healthful eating and active living behaviors in elementary school children participating in Educational Theatre Programs (ETP). METHODS: The study sample included 47 schools (2,915 third- or fourth-grade students) in 8 Kaiser Permanente regions. Children's knowledge of 4 healthful behaviors was measured using a brief survey before and immediately after performances, followed by a post-delay survey 3 weeks later. RESULTS: Statistically significant increases in knowledge pre/post for individual topics (P < .01). The percentage of children who answered all 4 questions correctly increased from 17% to 63% immediately after ETP performances (P < .01). Knowledge was retained over the short term; the proportion of students who correctly identified recommended healthful eating/active living practices had declined only slightly 3 weeks later. CONCLUSIONS AND IMPLICATIONS: The ETP significantly improved participating students' knowledge of healthful eating and active living concepts. Theater programs should be considered for inclusion in elementary school health curricula.

The human ecology of tornadoes

This paper offers an empirical test of the impact of human ecological patterns and other known correlates on tornado occurrence. It uses the National Severe Storms Forecast Center's information on tornadoes from 1950 through 1990 and employs ecological data from the U.S. Bureau of the Census and the Environmental Protection Agency. The results show that metropolitan and other urban counties have higher odds of tornado occurrence than rural counties, and that the probability of occurrence of tornadoes increases with increases in the number of previous tornadoes. The paper assesses the meaning of this finding for demographers, atmospheric scientists, engineers, and disaster managers.(AU)