Bootstrap Estimation of Benchmark Doses and Confidence Limits with Clustered Quantal Data

The benchmark dose (BMD) is an exposure level that would induce a small risk increase (BMR level) above the background. The BMD approach to deriving a reference dose for risk assessment of noncancer effects is advantageous in that the estimate of BMD is not restricted to experimental doses and utilizes most available dose-response information. To quantify statistical uncertainty of a BMD estimate, we often calculate and report its lower confidence limit (i.e., BMDL), and may even consider it as a more conservative alternative to BMD itself. Computation of BMDL may involve normal confidence limits to BMD in conjunction with the delta method. Therefore, factors, such as small sample size and nonlinearity in model parameters, can affect the performance of the delta method BMDL, and alternative methods are useful. In this article, we propose a bootstrap method to estimate BMDL utilizing a scheme that consists of a resampling of residuals after model fitting and a one-step formula for parameter estimation. We illustrate the method with clustered binary data from developmental toxicity experiments. Our analysis shows that with moderately elevated dose-response data, the distribution of BMD estimator tends to be left-skewed and bootstrap BMDL s are smaller than the delta method BMDL s on average, hence quantifying risk more conservatively. Statistically, the bootstrap BMDL quantifies the uncertainty of the true BMD more honestly than the delta method BMDL as its coverage probability is closer to the nominal level than that of delta method BMDL. We find that BMD and BMDL estimates are generally insensitive to model choices provided that the models fit the data comparably well near the region of BMD. Our analysis also suggests that, in the presence of a significant and moderately strong dose-response relationship, the developmental toxicity experiments under the standard protocol support dose-response assessment at 5% BMR for BMD and 95% confidence level for BMDL.     

建设项目的专业技术 服务风险管理浅析

本文分析了建设项目中专业技术服务的潜在风险，探讨了风险管理的内容、途径和方法，简述了专业责任保险的特点和原则，指出了在我国开展专业责任保险的紧迫性。     

国有无形资产流失问题探讨

文章根据经济全球化和知识化的客观要求,在分析国有无形资产流失的特征、途径的基础上,从强化观念、建立机构、完善制度、制定战略、营造环境等方面提出了防止国有无形资产流失的一系列对策。     

《蒙特利尔公约》下的赔偿责任体系及相关问题

1999年《蒙特利尔公约》随着美国作为第30个国家的加入,已于2003年11月4日正式生效。经我国人民代表大会批准,公约于2005年7月31日对我国生效。本文通过对《蒙特利尔公约》与其之前的公约(华沙公约体系和IATA责任体制)进行比较,阐述了公约的重要意义及重要新增内容,探讨了公约相关问题。     

腊八趣话

“腊八”,即农历的十二月初八日。它是中国古代极为重要的传统节日。从时序上看,过了腊八,春节就指日可待了。农历的十二月称“腊月”。“腊与“猎”字通。其原始义为:人们在用猎获的牺牲举行祭礼,驱邪避灾,纳福迎祥。《礼记·效特牲》中有:“伊耆氏始为蜡。蜡也者,索也岁十二月,合聚万物而索飨之也的记载。但腊月初八日作为一个节日,是从南北朝才渐至成型的。戎昱有一首《桂州腊夜》的诗:坐到三更尽,归仍万里赊。雪声偏傍竹,寒梦不离家。晓角分残漏,孤灯落碎花。二年随骠骑,辛苦向天涯。这是作者腊夜的怀乡之作。羁之思,人生况味,溢于其间…     

A survey of the family planning work done in Dongguan County

The total fertility rate of women of childbearing age of Dongguan County in China has been decreasing gradually from 5.9 during the period following the liberation in 1949 to 2.05 in 1982. In order to encourage young couples to implement the policy of family planning consciously, the people's government of Dongguan county decided in July 1980 that all cadres and employees in county towns who received 1-child certificates would be exempted from house rent of 45 square meters from the time they get their certificates and would be allocated a living space of a 2-children family until their children reached age 16. It also stipulated that every couple could enjoy 1 month's holiday every year for 3 years and during the holiday, their salary, bonus and rate of attendance would not be affected. Because women bear less children today, they are relieved from heavy household chores and become the main working force in collective production. As a result, the development of town-run enterprises was stimulated and the total industrial output value of these enterprises increased. The average monthly salary of each female worker is about 100 yuan. In 1984, the average income per capita of the country rose to 649.2 yuan. The implementation of family planning work has eased the tension in the education field. Previously, because of the large number of school-age children in rural areas, teachers had to teach 2 classes. In the past 4 years, great emphasis was laid on intellectual investment. During this period, 2351 schools were built and several fundraising projects were implemented. Since 1981, more than 200 new running water projects were built, and new public services have been developed, including old age homes.     

翻译中心智距离存在的客观性

翻译难是一个众所周知的事实。难的原因有多种,涉及许多内在和外在诸因素,其中有一个不容忽视的成因是译者与原作者之间客观地存在着“心智距离”,即译者在语际传译过程中,受自身诸种内在因素的制约,不可能真正地深入到原作者的内心中去,与原作者同思维、共呼吸,与原作者的意旨彻底复合。当代西方流行的接受美学理论为这一现象作了很好的佐证。     

Modeling household fertility decisions with generalized Poisson regression

This paper models household fertility decisions by using a generalized Poisson regression model. Since the fertility data used in the paper exhibit under-dispersion, the generalized Poisson regression model has statistical advantages over both standard Poisson and negative binomial regression models, and is suitable for analysis of count data that exhibit either over-dispersion or under-dispersion. The model is estimated by the method of maximum likelihood. Approximate tests for the dispersion and goodness-of-fit measures for comparing alternative models are discussed. Based on observations from the Panel Study of Income Dynamics of 1989 interviewing year, the empirical results support the fertility hypothesis of Becker and Lewis (1973). Received January 7, 1997 /Accepted April 3, 1997     

獭兔养殖综合技术研究

对獭兔的适应性、饲养管理、疾病防治、产品加工等养殖综合技术进行了研究,提出了獭兔的“三改、两杯、两早一分和两选两适”规范化饲养管理制度和疾病综合防治技术措施,探索出了优质獭兔毛皮和“富钙兔肉脯”的加工工艺以及獭兔良种推广的有效途径。     

多重网络中的词学研究

近20年来,词学研究有所进展,但仍存在一些问题。词学研究应在多重网络中展开。首先,词学是专门之学,但研究者仍需建构开放的知识网络。词乐研究虽有不少成果,但仍处于相对低潮。这与研究者受限于音乐知识,无法有效介入有关。词谱、词律等专门之学亦是如此。其次,可以尝试词学研究的时空延展,打造通观的“全息网络”,通过长时段的、大量的文本分析发现新话题。同时,注意域外汉籍,因为它们可以提供新文献,启发新视角,丰富文本网络。最后,要注意数字人文的发展趋向,要建设词学检索库,善用新技术,更新研究理念,以便及时因应。但数字人文终究只是辅助研究手段,技术取代不了阅读与思考,只有在传统研究的基础上,技术才能发挥更大的作用。