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671.
This article examines the failed convergence of sociology, social psychology, cultural anthropology, and clinical psychology in Harvard’s Department of Social Relations. The analysis shows that from its inception, the department was torn by fundamental contradictions involving membership criteria, stratification, the opposed needs of faculty and students, and the requisites of disciplinary autonomy. These conflicts, which were especially intense with regard to psychology, ultimately made the department ungovernable and led to the restoration of earlier administrative boundaries.  相似文献   
672.
Many statistical agencies, survey organizations, and research centers collect data that suffer from item nonresponse and erroneous or inconsistent values. These data may be required to satisfy linear constraints, for example, bounds on individual variables and inequalities for ratios or sums of variables. Often these constraints are designed to identify faulty values, which then are blanked and imputed. The data also may exhibit complex distributional features, including nonlinear relationships and highly nonnormal distributions. We present a fully Bayesian, joint model for modeling or imputing data with missing/blanked values under linear constraints that (i) automatically incorporates the constraints in inferences and imputations, and (ii) uses a flexible Dirichlet process mixture of multivariate normal distributions to reflect complex distributional features. Our strategy for estimation is to augment the observed data with draws from a hypothetical population in which the constraints are not present, thereby taking advantage of computationally expedient methods for fitting mixture models. Missing/blanked items are sampled from their posterior distribution using the Hit-and-Run sampler, which guarantees that all imputations satisfy the constraints. We illustrate the approach using manufacturing data from Colombia, examining the potential to preserve joint distributions and a regression from the plant productivity literature. Supplementary materials for this article are available online.  相似文献   
673.
This research analyzes the internal service supply chain of a perioperative surgical services department of a nonacademic community hospital using the theory of swift and even flow as a theoretical lens. Performance data were gathered using an in‐depth case study and it was determined that the swift and even flow constructs did affect flow speed and variance, but did not account for all the effects observed. To understand the need for departments to coordinate their efforts with each other and how this affected flow, further analysis was conducted using insights from Pagell's (2004) theory of internal integration and Gittell's (2002) research about coordinating mechanisms. The findings suggest the need to incorporate a variable measuring supply chain coordination into the theory of swift and even flow.  相似文献   
674.
We consider a continuous‐review inventory problem for a retailer who faces random disruptions both internally and externally (from its supplier). We formulate the expected inventory cost at this retailer and analyze the properties of the cost function. In particular, we show that the cost function is quasi‐convex and therefore can be efficiently optimized to numerically find the optimal order size from the retailer to the supplier. Computational experiments provide additional insight into the problem. In addition, we introduce an effective approximation of the cost function. Our approximation can be solved in closed form, which is useful when the model is embedded into more complicated supply chain design or management models.  相似文献   
675.
676.
生态批评是劳伦斯.布依尔十余年来的研究重点。程相占提出有两种生态批评:一种可以称为"生态文学批评",它是一种文学理论或文学批评;另外一种可以称为"生态文化批评",它的主要目的是重新考察某种文化传统对于自然的态度、对于环境的文化构建。劳伦斯.布依尔则认为二者的区分并不明确,他从理论上总结了生态批评运动的主要趋势和几种研究方式,指出第二阶段的生态批评日益将其基础放置在"环境正义(公平)"的伦理范式上。程相占认为生态批评最初关心的是自然或自然环境问题,但考虑到城市和都市区域是最大的人建环境,"环境批评"这个术语包容的对象范围更宽广。劳伦斯.布依尔的主要著作之所以都采用"环境批评"术语,原因之一在于他对城市环境的重视,其研究与环境美学有着一致之处。  相似文献   
677.
Model selection strategies play an important, if not explicit, role in quantitative research. The inferential properties of these strategies are largely unknown, therefore, there is little basis for recommending (or avoiding) any particular set of strategies. In this paper, we evaluate several commonly used model selection procedures [Bayesian information criterion (BIC), adjusted R 2, Mallows’ C p, Akaike information criteria (AIC), AICc, and stepwise regression] using Monte-Carlo simulation of model selection when the true data generating processes (DGP) are known.

We find that the ability of these selection procedures to include important variables and exclude irrelevant variables increases with the size of the sample and decreases with the amount of noise in the model. None of the model selection procedures do well in small samples, even when the true DGP is largely deterministic; thus, data mining in small samples should be avoided entirely. Instead, the implicit uncertainty in model specification should be explicitly discussed. In large samples, BIC is better than the other procedures at correctly identifying most of the generating processes we simulated, and stepwise does almost as well. In the absence of strong theory, both BIC and stepwise appear to be reasonable model selection strategies in large samples. Under the conditions simulated, adjusted R 2, Mallows’ C p AIC, and AICc are clearly inferior and should be avoided.  相似文献   

678.
The authors explored relationships among childhood abuse, suicidal ideation, and sexual orientation of 18- to 30-year-old students enrolled in 2 San Diego area colleges, using responses from anonymous questionnaires. Sixty percent of the 138 eligible respondents were women, and 22% were self-identified gay/bisexual individuals. Women were more likely than men to report at least 1 form of emotional abuse (odds ratio [OR] = 2.3; p =.02) and unwanted sexual touching (OR = 4.3; p = .0004). Lesbian/bisexual women were significantly more likely to report past suicidal ideation than were heterosexual women (OR = 3.7, p = .03). Gay/bisexual men were more likely to report unwanted sexual touching than were heterosexual men (OR = 5.1, p = .04), but the men did not report significantly higher rates of past suicide ideation or suicide attempts. Sexual orientation and a past history of child sexual, physical, and emotional abuse could be compounding risk factors for suicidal ideation among college students.  相似文献   
679.
We review conceptual issues and theoretical frameworks related to users' acceptability of new technologies designed to protect reproductive health and prevent unwanted pregnancy. Special attention is given to distinctions among different kinds of users' perspectives regarding acceptability, as well as differentiating acceptability from assessments of the efficacy of innovative methods. Emphasis is also given to the larger context of couple decision-making and cultural variation. We argue that concern for sexual pleasure plays a central role in determining user perspectives regarding new methods. The female condom, contraceptive ring, contraceptive skin patch, microbicides, vaccines, emergency contraception, and PERSONA are discussed within the context of the identified critical issues .  相似文献   
680.
In “Crime and Juvenile Delinquency,” Lawrence W. Sherman, a professor at the University of Pennsylvania’s Department of Sociology, describes how changes in criminal and other dysfunctional behaviors could be measured. He relies on data from the National Crime Victimization Survey and the Uniform Crime Reporting System. Sherman describes how criminal behavior tends to be concentrated in inner-city neighborhoods. He contends that “it is misleading to compare homicide rates across cities or to look at national homicide rates without disaggregating them by the factors that are most strongly correlated with their existence.” Although individual characteristics, such as age, race, and income, are important, he notes that “the effects of those characteristics are magnified by location and space.”  相似文献   
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