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21.
Sample selection in radiocarbon dating   总被引:1,自引:0,他引:1  
Archaeologists working on the island of O'ahu, Hawai'i, use radiocarbon dating of samples of organic matter found trapped in fish-pond sediments to help them to learn about the chronology of the construction and use of the aquicultural systems created by the Polynesians. At one particular site, Loko Kuwili, 25 organic samples were obtained and funds were available to date an initial nine. However, on calibration to the calendar scale, the radiocarbon determinations provided date estimates that had very large variances. As a result, major issues of chronology remained unresolved and the archaeologists were faced with the prospect of another expensive programme of radiocarbon dating. This paper presents results of research that tackles the problems associated with selecting samples from those which are still available. Building on considerable recent research that utilizes Markov chain Monte Carlo methods to aid archaeologists in their radiocarbon calibration and interpretation, we adopt the standard Bayesian framework of risk functions, which allows us to assess the optimal samples to be sent for dating. Although rather computer intensive, our algorithms are simple to implement within the Bayesian radiocarbon framework that is already in place and produce results that are capable of direct interpretation by the archaeologists. By dating just three more samples from Loko Kuwili the expected variance on the date of greatest interest could be substantially reduced.  相似文献   
22.
The matching identification problem (MIP) is a combinatoric search problem related to the fields of learning from examples, boolean functions, and knowledge acquisition. The MIP involves identifying a single “goal” item from a large set of items. Because there is commonly a cost associated with evaluating each guess, the goal item should be identified in as few guesses as possible. As in most search problems, the items have a similar structure, which allows an evaluation of each guessed item. In other words, each guessed item elicits partial information about the goal item, i.e. how similar the guess is to the goal. With this information the goal is more quickly identified.The unordered MIP has been studied by Mehrez and Steinberg (ORSA J. Comput. 7 (1995) 211) in which they proposed two different types of algorithms. The purpose of the present paper is to suggest an improved Spanning Heuristic algorithm. Its improvement increases as the problem size increases. Further results and comparisons are derived for the unordered and ordered cases.This research shows that when the search space is very large, it is better to inquire from items that are known not to be the goal (they have been ruled out by previous guesses), for the purpose of acquiring more information about the goal. As the search space is narrowed, it is better to guess items that have not been ruled out.  相似文献   
23.
政府审计是对权力的监督和制约,现阶段,我国地方政府审计面临的发展困境主要是审计职能软化问题,针对地方政府审计存在的主要问题,剖析原因,从多角度提出解决审计职能软化的对策。  相似文献   
24.
《Journal of homosexuality》2012,59(10):1274-1302
This study used a correlational design with a sample of university students to clarify the relationships between attitude functions and homonegativity with respect to gender. Classic work on attitude functions posits that attitudes serve psychological needs for the attitude holder. Herek (1986b) adapted this theory to explain attitudes toward homosexuality. Herek (1987) identified four functions: ego-defensive (defense of threats to the self), value-expressive (expression of key values), social-expressive (expression of important social norms), and experiential (based on past experiences). Results suggested that men were more likely to attribute their attitudes to the ego-defensive function. Men and women were equally likely to attribute their attitudes to the experiential function. The ego-defensive function was the best predictor of homonegativity for men and women, whether they held generally positive or generally negative attitudes toward homosexuality. The experiential function did not predict homonegativity. Participants tended to be neither very homonegative nor very ego-defensive.  相似文献   
25.
The purpose of this study was to provide a more comprehensive understanding of the relation between early parent‐child interactions and subsequent behavior problems and how certain cognitive processes mediate this relation. Specifically, this study investigated whether attention, inhibition, and planning skills mediate the relation between attachment security and behavior problems. Data were collected as part of the National Institute of Child Health and Development‐Study of Early Child Care and Youth Development when children (N = 1004) were between 36 months and the third grade. Results from structural equation models indicated that sustained attention mediated the relation between disorganized attachment and social problems. Planning mediated the relation between disorganized attachment and subsequent thought problems, attention problems, and delinquent behavior. Avoidant, ambivalent, and disorganized attachment directly predicted several behavior problems. Implications for theory and future research are discussed.  相似文献   
26.
A procedure is proposed for testing the equality of k dependent correlation coefficients. The procedure is simulated utilizing Monte Carlo techniques; and, a method for post hoc probing is also suggested.  相似文献   
27.
以长沙市T区为分析案例,通过对T区进行调查研究,寻找当前长沙市社区管理模式存在的一些问题:管理体制的行政化,政府职能的错位与缺位,居民与社区中介组织参与社区管理程度低,社区工作任务繁重,等等。要解决当前社区管理存在的一系列问题,必须重新考析政府、社区、社区中介组织以及居民之间的关系,理顺社区管理体制,明确政府职能,大力培育社区中介组织,培养居民的参与意识,构建长沙市功能型社区管理模式。  相似文献   
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29.
Variable selection in elliptical Linear Mixed Models (LMMs) with a shrinkage penalty function (SPF) is the main scope of this study. SPFs are applied for parameter estimation and variable selection simultaneously. The smoothly clipped absolute deviation penalty (SCAD) is one of the SPFs and it is adapted into the elliptical LMM in this study. The proposed idea is highly applicable to a variety of models which are set up with different distributions such as normal, student-t, Pearson VII, power exponential and so on. Simulation studies and real data example with one of the elliptical distributions show that if the variable selection is also a concern, it is worthwhile to carry on the variable selection and the parameter estimation simultaneously in the elliptical LMM.  相似文献   
30.
清代的海外华文报刊是中国新闻事业的重要组成部分,也是海外华人华侨精神生活不可或缺的组成部分.在我国1000多年的新闻传播史中,清代海外华文报刊处于中国报刊走向近代化的初期和创始阶段,这些华文报刊在宣传爱国思想、弘扬传统文化、传播科技知识、引导政治导向,以及反映华侨华人的爱国之情和沟通与祖国的联系方面,发挥了重要的传媒功能.清代的海外华文报刊呈现出报刊生存时间普遍较短、处于当地主流文化之外、政治倾向性由弱到强的传播特点,但海外华文报刊的出现和发展也反映了华侨华人社会地位的提高.  相似文献   
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