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在短短数十年中,数据库得到了广泛的认同,越来越多的领域要求建设符合使用需要的各类数据库。在文书相关领域,数据库建设也同样受到重视。此方面,徽州文书的研究者成为先行者,2007年,黄山学院启动名为《徽州文书整理及管理软件研究》的人文社科项目,将校内所存徽州文书建立特色文献数据  相似文献   
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A novel method was used to incorporate in vivo host–pathogen dynamics into a new robust outbreak model for legionellosis. Dose‐response and time‐dose‐response (TDR) models were generated for Legionella longbeachae exposure to mice via the intratracheal route using a maximum likelihood estimation approach. The best‐fit TDR model was then incorporated into two L. pneumophila outbreak models: an outbreak that occurred at a spa in Japan, and one that occurred in a Melbourne aquarium. The best‐fit TDR from the murine dosing study was the beta‐Poisson with exponential‐reciprocal dependency model, which had a minimized deviance of 32.9. This model was tested against other incubation distributions in the Japan outbreak, and performed consistently well, with reported deviances ranging from 32 to 35. In the case of the Melbourne outbreak, the exponential model with exponential dependency was tested against non‐time‐dependent distributions to explore the performance of the time‐dependent model with the lowest number of parameters. This model reported low minimized deviances around 8 for the Weibull, gamma, and lognormal exposure distribution cases. This work shows that the incorporation of a time factor into outbreak distributions provides models with acceptable fits that can provide insight into the in vivo dynamics of the host‐pathogen system.  相似文献   
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Abstract

Grubbs and Weaver (1947 Grubbs, F. E., and C. L. Weaver. 1947. The best unbiased estimate of population standard deviation based on group ranges. Journal of the American Statistical Association 42 (238):22441. doi: 10.2307/2280652.[Taylor & Francis Online], [Web of Science ®] [Google Scholar]) suggest a minimum-variance unbiased estimator for the population standard deviation of a normal random variable, where a random sample is drawn and a weighted sum of the ranges of subsamples is calculated. The optimal choice involves using as many subsamples of size eight as possible. They verified their results numerically for samples of size up to 100, and conjectured that their “rule of eights” is valid for all sample sizes. Here we examine the analogous problem where the underlying distribution is exponential and find that a “rule of fours” yields optimality and prove the result rigorously.  相似文献   
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Clustering in high-dimensional spaces is nowadays a recurrent problem in many scientific domains but remains a difficult task from both the clustering accuracy and the result understanding points of view. This paper presents a discriminative latent mixture (DLM) model which fits the data in a latent orthonormal discriminative subspace with an intrinsic dimension lower than the dimension of the original space. By constraining model parameters within and between groups, a family of 12 parsimonious DLM models is exhibited which allows to fit onto various situations. An estimation algorithm, called the Fisher-EM algorithm, is also proposed for estimating both the mixture parameters and the discriminative subspace. Experiments on simulated and real datasets highlight the good performance of the proposed approach as compared to existing clustering methods while providing a useful representation of the clustered data. The method is as well applied to the clustering of mass spectrometry data.  相似文献   
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徐峻  罗薇 《世界民族》2012,(4):44-56
美国黑人和白人在选举投票上的差异性一直备受学界关注,但是亚裔美国人参与投票率低这个问题却没有得到应有的重视。利用"当前人口调查中关于投票和登记的附录",笔者分析评估了对于亚裔美国人及其他少数族群投票率低的四种解释,即社会经济(socio-economic)解释、文化适应(acculturation)解释、差异性回报(differential return)解释、制度障碍(institutional barriers)解释。笔者运用一种统计学模型,能够同时对登记和投票进行评估,得出了四点结论:第一,社会经济解释在解释白人与亚裔美国人的差异性时,没有像解释白人与其他少数族群的差异时那么有说服力;第二,作为文化适应的两项重要指标——移民身份和居住时间——直接影响到亚裔美国人和拉美裔美国人的选民登记,但对其投票的影响甚微;第三,教育通常对参与投票有积极的影响,但是教育对亚裔美国人参与率的影响相对低于其他族群,尤其是白人;第四,制度障碍,尤其是对于选民登记的各种要求,不同比例地屏蔽了很多亚裔美国人,其次是拉美裔美国人,去参与最后的投票。本文的反事实分析(counterfactual analyses)表明,如果没有选民登记这项要求,亚裔美国人和白人在选民投票上将没有区别。  相似文献   
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The proliferation of internships and the rise of professionalisation in higher education are, in France, frequently condemned as evidence of a quest for greater employability, driven by a skills-based approach. A comparative analysis of the methods used to prepare students for employment shows the degree to which the social mechanisms are homogeneous in England (employability) and in Sweden (bildning). In France, the transition from higher education to employment entails a process of pre-professionalisation. This is characterised by the dominant role of professional skills and their incorporation into the structure of initial education itself. Rather than the outcome of a process of commodification, this mechanism of pre-professionalisation is explained by the persistence of an idealized conception of “matching” that still profoundly marks the relations between education and employment in France.  相似文献   
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