Intervention Effects on Stage of Change Membership and Transitions among Adolescent Energy Balance Behaviors

The transition from childhood to adolescence is a crucial period for the development of healthy behaviors to be sustained later in life. With obesity a leading public health problem, the promotion of healthy behaviors has the potential to make a huge impact. The current study evaluated Stage of Change progression in a large (N = 4158) computer-delivered, Transtheoretical Model-tailored intervention focusing on physical activity and fruit and vegetable consumption (FV). Markov models were used to explore stage transitions and patterns of discrete change from sixth to ninth grade. Nested model comparisons examined the consistency of these patterns across time and intervention condition. Major findings supported models in which participants were free to transition forward and backward to any of the stages, but higher probabilities were observed for remaining in the same stage or for transitioning one or two stages forward. Participants in the intervention group had higher probabilities of transitioning toward Maintenance, with more change occurring relative to the comparison group during transitions from grades six to eight but not for grades eight to nine.

Temperature-dependent fecundity of overwintered Scirtothrips dorsalis (Thysanoptera: Thripidae) and its oviposition model with field validation

BACKGROUND

A population model can be a useful tool to understand population dynamics under various environmental factors, and can be useful for evaluating the efficacy of new management practices. This study was conducted to construct an oviposition model of overwintered Scirtothrips dorsalis as a part of its whole population model.

RESULTS

Adult longevity decreased with increasing temperature and ranged from 44.7 days at 13 °C to 9.9 days at 33 °C. S. dorsalis showed a maximum fecundity of 52.6 eggs female(-1) at 21 °C, which declined to 13.9 eggs female(-1) at 33 °C. Egg development time decreased from 28.41 days at 13 °C to 5.14 days at 29 °C and 5.5 days at 33 °C. An oviposition model was developed on the basis of three temperature-dependent submodels: total fecundity, age-specific oviposition rate and age-specific survival rate models

CONCLUSION

The oviposition model outputs followed the field occurrence patterns of S. dorsalis egg populations well, with a peak time discrepancy of 3-4 days. Our model should be useful for population modelling of S. dorsalis in agricultural crops. Furthermore, the present model can be independently used for the timing of spraying against S. dorsalis in IPM programmes of various crops.