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Mathematical and simulation models studying work-rest schedules in a production process are developed to arrive at an optimal rest policy to maximize work output per unit time. A CSMP simulation study is used to test the sensitivity of the results for different specific cases. 相似文献
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This study involved a school-based prevention program initiated to reduce alcohol, tobacco, and other drug (ATOD) use among adolescents in the Troy School District in the Detroit area. One purpose was to describe the current ATOD situation by investigating changes in reported ATOD use from 1987 to 1991. Another purpose was to explore and identify the most salient risk and protective factors present. In 1987, 1,490 students (comprising grades 8 and 11) and in 1991, 3,171 students (comprising grades 8 to 12) completed questionnaires. Significant decreases were found for use of most drugs with the exception of alcohol. Involvement in problem behaviors was identified as the most salient risk factor, while having a member of a non-using peer group was the most salient protective factor. Implications for the design of subsequent intervention programs are discussed. 相似文献
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This study examined long-term effects of a school/family/community substance abuse prevention partnership intervention lead by a Midwestern school district. Previous findings suggested that the program contributed to decreased tobacco and marijuana, but not alcohol, use prior to and after implementation between 1987 and 1991. The current study examined 8th-12th grade student drug use prevalence data from 1991 and 2003 to determine whether previous program effects were sustained. With one exception, reported lifetime and monthly cigarette use decreased below 1991 levels for all grades. Lifetime and monthly alcohol use decreased below 1991 levels for most grades, a result not previously detected. While still below national rates, reported lifetime use of marijuana increased for all grades over time. The intervention was effective in reducing cigarette and alcohol use over time and in suppressing marijuana use levels below national rates; however, these gains tended to erode in later high school grades. 相似文献
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