涂附磨具单位面积CaCO3含量分析方法的改进

以铜试剂代替氰化物作掩蔽剂 ,用EDTA容量法测定涂附磨具单位面积CaCO3 含量 ,获得了满意的效果。     

Assessing accuracy of a continuous screening test in the presence of verification bias

Summary.  In studies to assess the accuracy of a screening test, often definitive disease assessment is too invasive or expensive to be ascertained on all the study subjects. Although it may be more ethical or cost effective to ascertain the true disease status with a higher rate in study subjects where the screening test or additional information is suggestive of disease, estimates of accuracy can be biased in a study with such a design. This bias is known as verification bias. Verification bias correction methods that accommodate screening tests with binary or ordinal responses have been developed; however, no verification bias correction methods exist for tests with continuous results. We propose and compare imputation and reweighting bias-corrected estimators of true and false positive rates, receiver operating characteristic curves and area under the receiver operating characteristic curve for continuous tests. Distribution theory and simulation studies are used to compare the proposed estimators with respect to bias, relative efficiency and robustness to model misspecification. The bias correction estimators proposed are applied to data from a study of screening tests for neonatal hearing loss.     

Three-level main-effects designs exploiting prior information about model uncertainty

To explore the projection efficiency of a design, Tsai, et al [2000. Projective three-level main effects designs robust to model uncertainty. Biometrika 87, 467–475] introduced the Q criterion to compare three-level main-effects designs for quantitative factors that allow the consideration of interactions in addition to main effects. In this paper, we extend their method and focus on the case in which experimenters have some prior knowledge, in advance of running the experiment, about the probabilities of effects being non-negligible. A criterion which incorporates experimenters’ prior beliefs about the importance of each effect is introduced to compare orthogonal, or nearly orthogonal, main effects designs with robustness to interactions as a secondary consideration. We show that this criterion, exploiting prior information about model uncertainty, can lead to more appropriate designs reflecting experimenters’ prior beliefs.     

电子商务的智能化营销

互联网和电子商务的出现,在信息获得的手段和方法上突破了传统时空观念的限制,在多方面动摇了企业经营和营销理论的根基。同时也改变了企业外部经营和购销的实务操作模式。传统行业的电子商务得到了广泛的应用,积累了大量的数据,在强大的数据库技术和数据挖掘工具的支持下,从海量的数据中挖掘出有用的信息来提高企业经营管理水平已成为热门的课题,为企业实现智能化营销提供了坚实的基础。     

Modeling the Adenoma and Serrated Pathway to Colorectal CAncer (ASCCA)

Several colorectal cancer (CRC) screening models have been developed describing the progression of adenomas to CRC. Currently, there is increasing evidence that serrated lesions can also develop into CRC. It is not clear whether screening tests have the same test characteristics for serrated lesions as for adenomas, but lower sensitivities have been suggested. Models that ignore this type of colorectal lesions may provide overly optimistic predictions of the screen‐induced reduction in CRC incidence. To address this issue, we have developed the Adenoma and Serrated pathway to Colorectal CAncer (ASCCA) model that includes the adenoma‐carcinoma pathway and the serrated pathway to CRC as well as characteristics of colorectal lesions. The model structure and the calibration procedure are described in detail. Calibration resulted in 19 parameter sets for the adenoma‐carcinoma pathway and 13 for the serrated pathway that match the age‐ and sex‐specific adenoma and serrated lesion prevalence in the COlonoscopy versus COlonography Screening (COCOS) trial, Dutch CRC incidence and mortality rates, and a number of other intermediate outcomes concerning characteristics of colorectal lesions. As an example, we simulated outcomes for a biennial fecal immunochemical test screening program and a hypothetical one‐time colonoscopy screening program. Inclusion of the serrated pathway influenced the predicted effectiveness of screening when serrated lesions are associated with lower screening test sensitivity or when they are not removed. To our knowledge, this is the first model that explicitly includes the serrated pathway and characteristics of colorectal lesions. It is suitable for the evaluation of the (cost)effectiveness of potential screening strategies for CRC.     

Foot-and-Mouth Disease Entrance Assessment Model Through Air Passenger Violations

This article aims to construct a risk model for the prediction of foot-and-mouth disease (FMD) entrance caused by passengers who illegally carry meat products of cloven-hoofed animals through international airports into a country. The risk that meat contaminated with the FMD virus is formulated as the probabilities of FMD factor events (the prevalence of FMD), the commodity factor event (the transportation, storage, and distribution (TSD) factor event), and the passenger event. Data used for analysis were records of illegal meat product carriers from areas A and B intercepted at an international airport in Taiwan. A risk model was proposed to simulate the probability distributions in disease prevalence, probability of FMD virus existing in the meat products after meat processing, and estimation of survival of virus and time period for TSD. The probability of the passenger event was hypothesized with the odds of intercepted passengers and estimated via logistic regression. The results showed that the odds of passengers being intercepted by beagles were higher than those intercepted by Customs. By conducting Monte Carlo simulations, the probability of FMD virus risk caused by FMD factors from area A was 149 times lower than that from area B. The probability of FMD virus risk caused by the passenger event from area A was four times lower than the corresponding probability from area B. The model provides a contribution to FMD prevention and can be a reference for developing models of other diseases.     

信息不对称下医药营销服务外包契约设计

为了缩减销售成本,一些制药企业将营销服务外包给合约销售公司(contract sales organization,CSO).由于CSO的营销努力不可合同化,制药企业需要基于市场销量来激励CSO的营销努力.然而,市场销量受制药企业定价决策的影响,因此CSO将面临制药企业提高定价的道德风险.此外,药品营销难度信息可能是CSO的私人信息,这使得制药企业面临逆向选择问题.当制药企业将营销服务外包给多个CSO时,由于制药企业针对同一药品在不同市场的售价相同,其定价决策对多个CSO所服务市场的销量具有共同的影响.相对绩效的激励契约能够消除共同不确定因素对代理人产出的影响,从而更有利于激励代理人付出高水平的努力.因此依据信息甄别的博弈模型,分析基于个体绩效与基于相对绩效的激励契约的有效性.研究发现:1)药品营销难度信息对称时,基于相对绩效的激励契约占优于基于个体绩效的激励契约,且可以获得全局最优的营销努力和期望利润;2)药品营销难度信息不对称时,两种激励契约均不能获得全局最优的营销努力和期望利润.数值分析表明,药品营销难度的先验概率,市场价格敏感性和高低类型药品营销难度差异的变化会影响制药企业的契约选择,较高的市场价格敏感性和较低的高低类型药品营销难度差异使得基于相对绩效的激励契约更有效.     

Factor screening in nonregular two-level designs based on projection-based variable selection

In this paper, we focus on the problem of factor screening in nonregular two-level designs through gradually reducing the number of possible sets of active factors. We are particularly concerned with situations when three or four factors are active. Our proposed method works through examining fits of projection models, where variable selection techniques are used to reduce the number of terms. To examine the reliability of the methods in combination with such techniques, a panel of models consisting of three or four active factors with data generated from the 12-run and the 20-run Plackett–Burman (PB) design is used. The dependence of the procedure on the amount of noise, the number of active factors and the number of experimental factors is also investigated. For designs with few runs such as the 12-run PB design, variable selection should be done with care and default procedures in computer software may not be reliable to which we suggest improvements. A real example is included to show how we propose factor screening can be done in practice.     

中国最早出现的外国邮戳

鸦片战争前,澳门和广州是中国重要的通商口岸和中西文化交流中心。葡萄牙和英国为满足邮政通信的需求,在两地非法建立了最早的外国邮局,并使用了最早的外国邮戳。外国邮戳在中国经历了多次变化,它既反映了外国侵略中国邮权政策的转变,又为深入研究清代中外关系提供了宝贵资料。     

不确定性分析与风险分析在铁路投资项目中的应用

不确定性分析与风险分析是铁路投资项目可行性研究的重要组成部分,了解项目所承受的各种风险,有助于提高投资决策的可靠性,提高投资项目的风险防范能力。基于概率分析的定量风险分析为铁路项目的可行性研究提供了一个非常有效的风险分析工具。本文在深入分析铁路投资项目风险因素的基础上,重点阐述了蒙特卡洛模拟的方法、步骤和在铁路项目中的应用。结果表明该方法在铁路项目投资决策中具有较高的实用价值。