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61.
If a specific biological mechanism could be determined by which a carcinogen increases lung cancer risk, how might this knowledge be used to improve risk assessment? To explore this issue, we assume (perhaps incorrectly) that arsenic in cigarette smoke increases lung cancer risk by hypermethylating the promoter region of gene p16INK4a, leading to a more rapid entry of altered (initiated) cells into a clonal expansion phase. The potential impact on lung cancer of removing arsenic is then quantified using a three‐stage version of a multistage clonal expansion (MSCE) model. This refines the usual two‐stage clonal expansion (TSCE) model of carcinogenesis by resolving its intermediate or “initiated” cell compartment into two subcompartments, representing experimentally observed “patch” and “field” cells. This refinement allows p16 methylation effects to be represented as speeding transitions of cells from the patch state to the clonally expanding field state. Given these assumptions, removing arsenic might greatly reduce the number of nonsmall cell lung cancer cells (NSCLCs) produced in smokers, by up to two‐thirds, depending on the fraction (between 0 and 1) of the smoking‐induced increase in the patch‐to‐field transition rate prevented if arsenic were removed. At present, this fraction is unknown (and could be as low as zero), but the possibility that it could be high (close to 1) cannot be ruled out without further data.  相似文献   
62.
63.
The proportion of the population out of work is an unsatisfactory measure of unemployment because it is indifferent to the way in which a given amount of unemployment time is distributed across the population. This paper offers a new way of measuring unemployment which takes account of both the frequency and duration of unemployment spells. The proposed unemployment index may be interpreted as the ‘welfare equivalent’ period of unemployment, and decomposes into the product of three components: a spell incidence factor, a duration factor, and the average unemployment rate.  相似文献   
64.
How can we best allocate limited defensive resources to reduce terrorism risks? Dillon et al.'s Antiterrorism Risk-Based Decision Aid (ARDA) system provides a useful point of departure for addressing this crucial question by exhibiting a real-world system that calculates risk reduction scores for different portfolios of risk-reducing countermeasures and using them to rank-order different possible risk mitigation alternatives for Navy facilities. This comment points out some potential limitations of any scoring system that does not take into account risk externalities, interdependencies among threats, uncertainties that are correlated across targets, and attacker responses to alternative allocations of defensive resources. In at least some simple situations, allocations based on risk reduction scores and comparisons can inadvertently increase risks by providing intelligent attackers with valuable information, or they can fail to reduce risks as effectively as nonscoring, optimization-based approaches. These limitations of present scoring methods present exciting technical challenges and opportunities for risk analysts to develop improved methods for protecting facilities and infrastructure against terrorist threats.  相似文献   
65.
Penicillin and ampicillin drugs are approved for use in food animals in the United States to treat, control, and prevent diseases, and penicillin is approved for use to improve growth rates in pigs and poultry. This article considers the possibility that such uses might increase the incidence of ampicillin-resistant Enterococcus faecium (AREF) of animal origin in human infections, leading to increased hospitalization and mortality due to reduced response to ampicillin or penicillin. We assess the risks from continued use of penicillin-based drugs in food animals in the United States, using several assumptions to overcome current scientific uncertainties and data gaps. Multiplying the total at-risk population of intensive care unit (ICU) patients by a series of estimated factors suggests that not more than 0.04 excess mortalities per year (under conservative assumptions) to 0.14 excess mortalities per year (under very conservative assumptions) might be prevented in the whole U.S. population if current use of penicillin drugs in food animals were discontinued and if this successfully reduced the prevalence of AREF infections among ICU patients. These calculations suggest that current penicillin usage in food animals in the United States presents very low (possibly zero) human health risks.  相似文献   
66.
This article describes how a risk-return portfolio analysis, as originally developed in economics and finance, can be applied to product-line decisions. This approach uses direct estimates of return, and explicitly considers risk, or variation in return; most of the product portfolio models in use today forecast return by correlation, and lack explicit treatment of risk. The approach provides guidance for new product development activities as well as for allocating resources among a corporation's existing product lines. The article explains how organizations can apply this approach to their own product portfolio decisions, and includes a detailed example of how one company used this model.  相似文献   
67.
A pre-defined list of family therapy intervention strategies was used to predict post-therapy perceived life happiness and marital happiness among husbands and wives. Clients presented with both child and marriage-focused problems. The data were analyzed separately for husbands and wives. In general, favorable outcome for husbands was associated with active restructuring operations on the part of the therapist. Prediction of outcome for wives was less clear. However, wives did appear to respond favorably to less active interventions such as actualizing transactional patterns and reframing.  相似文献   
68.
Abstract In recent years, several agricultural cooperatives have undergone significant restructuring. Some have been taken through a conversion process and have been reorganized as “investor-oriented firms” (IOFs). This phenomenon has attracted the interest of agricultural economists, but it has not been analyzed by sociologists. This article examines the discourse with which agricultural economists have approached the conversion issue. Drawing upon Fraser's discussion of “needs talk,” and inspired by Kloppenburg's analysis of the agricultural scientific complex, an argument is made that a reprivatization discourse of neoclassical economics has effectively depoliticized discussion about the future of cooperative enterprise. It is further argued that a repoliticization of cooperation is necessary in order to assure the protection of extra-economic values and oppositional discourse that is embedded in the historical development of cooperative practices and institutions. We focus here on the role of expert discourse as it relates to the reinvention of cooperative institutions in the agricultural economy. It is argued that this discourse would be improved by greater attention to historical and sociological forces, rather than remaining narrowly focused on economism.  相似文献   
69.
This paper attempts to analyze the social, economic, and political sources for the emergence of modern Soviet sociology in the 1950s. While it does not address extensively the characteristics of current Soviet sociology, it is suggested that those characteristics of a methodologically sophisticated and economically oriented sociology are largely the result of a compact between Soviet leaders and sociologists which allowed and required its post-Stalin emergence. Four sets of factors are evaluated in terms of their effect on the emergence of Soviet sociology. These are 1) the Marxist-Leninist vision (that is, the Utopian elements of ideology), 2) the Soviet ideology (that is, the elements of ideology oriented toward system maintenance), 3) the diffusion of ideas, and 4) the mandate of Soviet economic development. A brief evaluation of these sets of factors as they affect the emergence of Chinese sociology in the early 1980s is also provided. It is concluded that the future shape of sociology in the USSR and China is dependent upon the evolution of ideology in the two countries, an evolution that is intimately tied to the succession of political leadership.  相似文献   
70.
The perceived severity of the problem of “drift” in the foster care system has encouraged agencies nationwide to accept permanency planning, but perhaps with limited attention to the planning process. This article examines the phenomenon of permanency planning from a planning perspective by focusing on: (a) definition of the permanency planning problem, (b) understanding of issues relevant to permanency planning (caseworker, program and systemic), (c) appreciation of the operational context (political, economic and social factors), and (d) evaluation of available options and possible consequences in developing or improving a permanency planning program. Permanency planning is not a simple, ready-made program applicable to any situation; it involves coordinated efforts by workers, service systems, and society in general, and requires time, commitment and resources. Successful planning for permanency planning can permit more children to grow up in homes providing continuity and stability.  相似文献   
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