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81.
A novel approach to pure 0-1 integer programming problems called Resolution Search has been proposed by Chvatal (Discrete Applied Mathematics, vol. 73, pp. 81–99, 1997) as an alternative to implicit enumeration, with a demonstration that the method can yield more effective branching strategies. We show that an earlier method called Dynamic Branch-and-Bound (B&B) yields the same branching strategies as Resolution Search, and other strategic alternatives in addition. Moreover, Dynamic B&B is not restricted to pure 0-1 problems, but applies to general mixed integer programs containing both general integer and continuous variables.We provide examples comparing Resolution Search to enhanced variants. We also show the relation of these approaches to Dynamic B&B, suggesting the value of further study of this neglected approach.  相似文献   
82.
This study examines the prevalence of gambling and measures the relationships between gambling behavior and a number of demographic, psychosocial, and behavioral variables among Minnesota public school students. The sample includes 78,582 male and female Minnesota public school students enrolled in the 9th and 12th grades. Students were administered the 1998 Minnesota Student Survey, a 121-item, anonymous, self-administered, paper-and-pencil questionnaire that inquires about multiple health-related content domains, including gambling behavior. The majority of students were found to have gambled at least once during the past year, however, most students did not report gambling frequently, nor did they report problems associated with their gambling. Boys reported gambling more often than girls, and older students gambled more often than younger students. A larger percentage of Mexican/Latin American, African American, American Indian, and mixed race students gambled at weekly and daily rates than Asian American and Caucasian students. Variables associated with gambling frequency included antisocial behavior, gender (being a male), alcohol and tobacco use, age, feeling bad about the amount of money they bet, a desire to stop gambling, and increased sexual activity. Gambling appears to be related to other risk-taking behaviors and may be a part of the adolescent experimentation with adult behaviors.  相似文献   
83.
This article shows the intersections of participatory research, popular education, empowerment planning, and community organizing with participatory evaluation. It argues that a truly successful participatory evaluation involves participants in guiding and even conducting the research, doing a process of self- and program study, creating plans for change, and organizing themselves for implementing these plans. Next, the chapter shows how these elements played out in a participatory evaluation of a community organizing training and technical assistance project in Toledo, Ohio. The first year of the project was facilitated by participatory evaluation that helped identify early successes and problems so participants could make programmatic changes early in the process. The telling of the story also develops practices of participatory evaluation, including planning the evaluation, doing the research and adapting it to changing conditions, uncovering creative tensions, participatory validity checking, and linking the process to planning and action. The chapter concludes with some lessons for participatory evaluation practice.  相似文献   
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85.
Phase II trials in oncology drug development are usually conducted to perform the initial assessment of treatment activity. The common designs in this setting, for example, Simon 2-stage designs, are often developed based on testing whether a parameter of interest, usually a proportion (e.g. response rate), is less than a certain level or not. These designs usually consider only one parameter. However, sometimes we may encounter situations where we need to consider not a single parameter, but multiple parameters. This paper presents a two-stage design in which both primary and secondary endpoints are utilized in the decision rules. The family-wise Type 1 error rate and statistical power of the proposed design are investigated under a variety of situations by means of Monte-Carlo simulations.  相似文献   
86.
This study measured the outcome of four state-supported outpatient gambling treatment programs in Minnesota. The programs were developed specifically for the treatment of pathological gamblers and offered multiple modalities of treatment including individual, group, education, twelve-step work, family groups, and financial counseling. The therapeutic orientation was eclectic with an emphasis on the twelve steps of Gamblers Anonymous (GA) and a treatment goal of abstinence. The sample included 348 men and 220 women treated between January 1992 and January 1995. A pretest-posttest design was utilized with multidimensional assessments obtained at intake, discharge, six-months, and twelve-months post-discharge. Variables assessed included a range of clinical and outcome variables. At six month follow-up, 28% reported that they had abstained from gambling during the six months following discharge and an additional 20% had gambled less than once per month. Almost half of the sample (48%) showed clinically significant improvement in gambling frequency at six monthfollow-up. Outcome variables of gambling frequency, SOGS scores, amount of money gambled, number of friends who gamble, psychosocial problems, and number of financial problems, all showed statistically significant improvements from pretreatment to follow-up. The treatment programs yielded outcome results similar to those reported for alcohol and drug abuse treatment programs.  相似文献   
87.
This essay presents the previously unpublished ‘Memoirs’ of Florence Hall, an African-born woman enslaved in early nineteenth-century Jamaica. The brief text describes Hall's childhood in Igboland (now southeastern Nigeria), her enslavement and journey to the Atlantic coast, her experience of the Middle Passage, and her arrival in Jamaica. There, the narrative abruptly cuts off. Evidently, the pages containing the rest of her story were lost. The text was likely written in the early nineteenth century, mediated by planter Robert Johnston, in whose papers the surviving text was found. As one of the only slave trade narratives from an African woman anywhere in the Americas, Hall's ‘Memoirs’ offer a rare opportunity to consider the transatlantic slave trade at its peak from the viewpoint of a female captive.  相似文献   
88.
This paper reports an experimental test of the Porter Hypothesis that environmental regulations create innovation offsets that would not otherwise be undertaken. Using a process analysis framework to consistently account for non-separabilities in production and pollution abatement practices, the findings suggest productivity gains can appear to be greater with environmental regulations than without even though they are not. This result which would seem to support the Porter argument, is the result of inadequacies in the methods used to decompose the influences to productivity change. Thus, the experiments offer one explanation for why it has been difficult in practice to reject the hypothesis.  相似文献   
89.
Abstract

The move from print to online journal publishing has allowed the proliferation of journal access programs aimed at poor countries. These programs offer access to online journals on very favorable terms to developing country institutions and readers and are based on the premise that developing world scientists can contribute significantly to ameliorating the conditions of life in their countries. The authors give a brief overview of the environment in which these programs emerged, discuss different orientations of the major programs, examine the case of the Health InterNetwork Access to Research Initiative (HINARI), consider why the World Health Organization (WHO) runs a journal access program for developing countries, and conclude with the accomplishments of HINARI.  相似文献   
90.
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