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771.
To date, the variant Creutzfeldt‐Jakob disease (vCJD) risk assessments that have been performed have primarily focused on predicting future vCJD cases in the United Kingdom, which underwent a bovine spongiform encephalopathy (BSE) epidemic between 1980 and 1996. Surveillance of potential BSE cases was also used to assess vCJD risk, especially in other BSE‐prevalent EU countries. However, little is known about the vCJD risk for uninfected individuals who accidentally consume BSE‐contaminated meat products in or imported from a country with prevalent BSE. In this article, taking into account the biological mechanism of abnormal prion PrPres aggregation in the brain, the probability of exposure, and the expected amount of ingested infectivity, we establish a stochastic mean exponential growth model of lifetime exposure through dietary intake. Given the findings that BSE agents behave similarly in humans and macaques, we obtained parameter estimates from experimental macaque data. We then estimated the accumulation of abnormal prions to assess lifetime risk of developing clinical signs of vCJD. Based on the observed number of vCJD cases and the estimated number of exposed individuals during the BSE epidemic period from 1980 to 1996 in the United Kingdom, an exposure threshold hypothesis is proposed. Given the age‐specific risk of infection, the hypothesis explains the observations very well from an extreme‐value distribution fitting of the estimated BSE infectivity exposure. The current BSE statistics in the United Kingdom are provided as an example.  相似文献   
772.
One of the most established approaches to explain attitudes toward immigration is group conflict theory. However, even though the theory was articulated in dynamic terms, previous research has almost exclusively tested it through cross‐sectional analyses. The aim of this study is to disentangle the dynamic character of ethnic competition from more permanent determinants of ethnic threat. The findings show that a remarkable variation of concern over immigration, usually attributed to permanent positions of economic vulnerability, disappears when within‐person variation is modeled. In line with a dynamic approach of ethnic competition, becoming unemployed or being laid off increases concern over immigration. This effect is independent of social class.  相似文献   
773.
Stability and change in kindergartners' friendships were examined based on a typology of profiles (stable, fluid, loss, gain, friendless). Our purpose was to determine whether children belonging to the five profiles differed in their social functioning. The sample was composed of 2353 kindergartners. Reciprocal friendships and social functioning indices were measured using peer nominations collected in October and May of the same year. A series of repeated measures analysis of variance indicated that children in the friendless profile were less accepted by their peers, more shy, more withdrawn, and more aggressive than other children. Moreover, children in the stable profile were significantly more accepted by their peers, more prosocial, and less shy than children in the fluid profile. Lastly, children in the loss profile became less accepted by their peers and less prosocial over the course of the year whereas children in the gain profile became more accepted and prosocial.  相似文献   
774.
Yakov Ben‐Haim 《Risk analysis》2012,32(10):1638-1646
Risk analysis is challenged in three ways by uncertainty. Our understanding of the world and its uncertainties is evolving; indeterminism is an inherent part of the open universe in which we live; and learning from experience involves untestable assumptions. We discuss several concepts of robustness as tools for responding to these epistemological challenges. The use of models is justified, even though they are known to err. A concept of robustness is illustrated in choosing between a conventional technology and an innovative, promising, but more uncertain technology. We explain that nonprobabilistic robust decisions are sometimes good probabilistic bets. Info‐gap and worst‐case concepts of robustness are compared. Finally, we examine the exploitation of favorable but uncertain opportunities and its relation to robust decision making.  相似文献   
775.
The Effective Provision of Pre‐school Education (EPPE) project is a longitudinal study of young children between the ages of 3 and 7 years. Research began in 1997 and both quantitative and qualitative methods were used to explore the effects of pre‐school education on children’s attainment and social/behavioural development at entry to school, and of any continuing effects on such outcomes at the end of Key Stage 1 (age 7). The sample included over 3,000 children and 141 pre‐school centres drawn from six different types of providers. In addition, a home sample of children who had not attended a pre‐school centre was included. In order to identify the processes that might influence centre effectiveness, observational data were collected and centre managers interviewed. In‐depth case studies of 12 more effective centres were used to explore and illuminate the processes, particularly in relation to pedagogy, associated with better child outcomes. A mixed method approach was adopted to simultaneously answer both confirmatory and exploratory questions, to support user engagement and provide triangulation. The paper argues that the mixed method approach supported the development of stronger research inferences.  相似文献   
776.
777.
Professional associations have provided various benefits to their members to bolster member retention and recruitment. This study explored factors that could influence members’ behavioral intentions in professional membership associations by surveying 13,229 members from eighteen associations. More specifically, this analysis focused on the effects of members’ perceptions of the personal and professional benefits offered by associations with which they are affiliated and their satisfaction with those benefits. Our results suggested that members’ perceptions of personal and professional benefits positively correlated with their intentions to renew and recommend membership. If a member perceived a higher level of benefits, he or she would demonstrate a greater likelihood of satisfaction with the benefits and therefore be more likely to renew membership or recommend it to others. This study could advance understanding of the factors that influence members’ behavioral intentions while also providing professional associations with strategies for retaining existing members.  相似文献   
778.
Using a unique data set of causal usage drawn from research articles published between 2006–2008 in the American Journal of Sociology and American Sociological Review, this article offers an empirical assessment of causality in American sociology. Testing various aspects of what we consider the conventional wisdom on causality in the discipline, we find that (1) “variablistic” or “covering law” models are not the dominant way of making causal claims, (2) research methods affect but do not determine causal usage, and (3) the use of explicit causal language and the concept of “mechanisms” to make causal claims is limited. Instead, we find that metaphors and metaphoric reasoning are fundamental for causal claims‐making in the discipline. On this basis, we define three dominant causal types used in sociology today, which we label the Probabilistic, Initiating and Conditioning types. We theorize this outcome as demonstrating the primary role that cognitive models play in providing inference‐rich metaphors that allow sociologists to map causal relationships on to empirical processes.  相似文献   
779.
This article compares different strategies for handling low‐ and medium‐level nuclear waste buried in a retired potassium mine in Germany (Asse II) that faces significant risk of uncontrollable brine intrusion and, hence, long‐term groundwater contamination. We survey the policy process that has resulted in the identification of three possible so‐called decommissioning options: complete backfilling, relocation of the waste to deeper levels in the mine, and retrieval. The selection of a decommissioning strategy must compare expected investment costs with expected social damage costs (economic, environmental, and health damage costs) caused by flooding and subsequent groundwater contamination. We apply a cost minimization approach that accounts for the uncertainty regarding the stability of the rock formation and the risk of an uncontrollable brine intrusion. Since economic and health impacts stretch out into the far future, we examine the impact of different discounting methods and rates. Due to parameter uncertainty, we conduct a sensitivity analysis concerning key assumptions. We find that retrieval, the currently preferred option by policymakers, has the lowest expected social damage costs for low discount rates. However, this advantage is overcompensated by higher expected investment costs. Considering all costs, backfilling is the best option for all discounting scenarios considered.  相似文献   
780.
This article draws upon responses given by volunteers who work in the Beijing LGBT Centre regarding perceptions of sexual identity, and how Chinese culture affects hidden or open sexual identities of Chinese lesbian and gay people in this region. The insights gained from those working carefully to create social change offers an important and original contribution to the field of gay and lesbian studies in China. The findings indicate the volunteers at the Beijing LGBT Centre are frustrated by the lack of acceptance of non‐heterosexual relationships among Chinese culture and society, and by the disregard of lesbian gay and bisexual (LGB) people by the Chinese government. The findings also illustrate stigmatization of homosexuality in China is enacted in structural terms (such as in the lack of policy, legislation and positive endorsement by governmental and socio‐political organizations), public expression (such as negative attitudes, beliefs or reactions towards LGB people) and internalized repression (through fear of stigmatization, and subsequent abuse due to negative societal attitudes and discrimination). Influenced by the Chinese tradition of conforming to group values, the findings from this study show that volunteers at the Beijing LGBT Centre believe LGB people in China are generally hesitant to disclose their sexual identities, and reject the idea that there had been a collective shift in Chinese culture regarding increased acceptance of LGB people. It also finds volunteers at the LGBT Centre in Beijing blame Chinese culture for its lack of acceptance of non‐heterosexual relationships, and state stigmatization of homosexuality in China is due to deep‐rooted cultural homophobia.  相似文献   
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