Evaluation of strategies to mitigate contagion spread using social network characteristics

Computer simulation is an effective tool for assessing mitigation strategies, with recent trends concentrating on agent-based techniques. These methods require high computational efforts in order to simulate enough scenarios for statistical significance. The population individuals and their contacts determined by agent-based simulations form a social network. For some network structures it is possible to gain high accuracy estimates of contagion spread based on the connection structure of the network, an idea that is utilized in this work. A representative social network constructed from the 2006 census of the Greater Toronto Area (Ontario, Canada) of 5 million individuals in 1.8 million households is used to demonstrate the efficacy of our approach. We examine the effects of six mitigation strategies with respect to their ability to contain disease spread as indicated by pre- and post-vaccination reproduction numbers, mean local clustering coefficients and degree distributions. One outcome of the analysis provides evidence supporting the design of mitigation strategies that aim to fragment the population into similarly sized components. While our analysis is framed in the context of pandemic disease spread, the approach is applicable to any contagion such as computer viruses, rumours, social trends, and so on.     

网络信息监控系统设计的研究

根据当前网络信息传播的混乱情况,在某种场合进行网络信息监控很有必要.该文提出了网络信息监控的几种实现方法和标准的信息监控流程,讨论设计网络信息监控系统的系统架构方法以及信息监控中应根据实际采用各种不同的技术组合,以达到全方位对网络信息进行监控.     

多波段光学探测系统的探测概率研究

针对光学联合探测子系统探测概率的不同特点,提出一种新的系统工作模式,使系统的最终探测概率有较大提高。当子系统的探测概率均比较低时,直接对子系统的探测数据进行融合,可以获得较高探测概率;当各子系统探测概率相差较大时,可先对探测数据进行选择,然后再进行数据融合,这样可以在总探测概率减小不大的情况下,使虚警概率明显降低。     

运用核Fisher鉴别分析和MPM分类器的入侵检测

为了提高分类器的正确率和减少训练时间,将特征提取技术与分类算法结合,提出了一种基于核Fisher鉴别分析和最小极大概率机算法的入侵检测算法。利用核Fisher鉴别分析技术提取关键特征,运用最小极大概率机对提取特征后的数据进行分类,采用离线数据集KDDCUP99进行实验。实验结果表明,该算法是可行和有效的,使分类性能和训练时间都得到了提高。     

秦皇岛开埠与发展的三大特征

一个城市早期的规划和发展在一定程度上决定着这个城市的前途和命运。在秦皇岛城市近代化的发展过程中,表现出三个明显的特征:一是分散的城市空间架构的互补共生;二是近代社团在城市发展过程中的重要作用;三是港城发展的严重失衡。     

Adapting by calibration the sample size of a phase III trial on the basis of phase II data

The problem of estimating the sample size for a phase III trial on the basis of existing phase II data is considered, where data from phase II cannot be combined with those of the new phase III trial. Focus is on the test for comparing the means of two independent samples. A launching criterion is adopted in order to evaluate the relevance of phase II results: phase III is run if the effect size estimate is higher than a threshold of clinical importance. The variability in sample size estimation is taken into consideration. Then, the frequentist conservative strategies with a fixed amount of conservativeness and Bayesian strategies are compared. A new conservative strategy is introduced and is based on the calibration of the optimal amount of conservativeness – calibrated optimal strategy (COS). To evaluate the results we compute the Overall Power (OP) of the different strategies, as well as the mean and the MSE of sample size estimators. Bayesian strategies have poor characteristics since they show a very high mean and/or MSE of sample size estimators. COS clearly performs better than the other conservative strategies. Indeed, the OP of COS is, on average, the closest to the desired level; it is also the highest. COS sample size is also the closest to the ideal phase III sample size M_I, showing averages and MSEs lower than those of the other strategies. Costs and experimental times are therefore considerably reduced and standardized. However, if the ideal sample size M_I is to be estimated the phase II sample size n should be around the ideal phase III sample size, i.e. n?2M_I/3. Copyright © 2010 John Wiley & Sons, Ltd.     

基于模糊神经网的入侵检测模型研究

对自组织特征映射(SOM)神经网络进行了概括分析,并结合模糊逻辑的思想对SOM网络的学习算法进行了模糊化改进。将模糊SOM技术应用到网络入侵检测中并应用MATLAB进行仿真。试验结果表明基于模糊神经网络的网络入侵检测方法能有效降低误报率。     

行业干中学、市场规模与市场结构——中国微观制造企业的实证研究

本文使用中国制造业微观企业1999至2007年的大样本数据,探讨干中学在市场规模扩张的过程中对市场结构动态变化的影响。研究发现,干中学有助于提高行业市场集中度的下限;其次,在较低的干中学行业中,随着市场规模的增加,行业会形成无序的片状的市场结构,行业集中度极度分散;然后,在动态的市场结构中,行业的干中学效应有助于缓解市场结构扩散,使行业市场结构的变动保持一种"粘性";最后,在很高的干中学行业中,行业的市场集中度会呈现U型的态势,当市场规模达到最佳市场规模后,行业的市场集中度开始上升,此时,内生的市场壁垒会催生行业的市场势力。     

Some sampling effects of pairwise correlated observations on likelihood ratio tests for the difference between two means

We study the effects of the inclusion of pairs of correlated observations in a sample on likelihood ratio tests for the difference in two means. In particular, we assess how the inclusion of correlated data pairs (e.g., such as data inadvertently collected from sib-pairs) affects the sample size requirements necessary for the implementation of a Likelihood Ratio (LR) test for the difference between two means. Our results suggest that correlated data pairs beneficially or adversely effect sample size requirements for an LR test to a degree functionally related to the mixture parameters dictating their relative frequencies in the larger sample on which the test will be performed, the strength of the correlation between the observations, and the size of imbalances in the sample with respect to the number of observations in each group. The relevance and implications of the results for genetic and epidemiologic research are discussed.     

现代汉语兼语结构的机器探测

采用统计与规则结合的方法对现代汉语兼语结构的机器探测方法展开研究,提出了用于自动探测兼语的＂兼语候选项特征＂与＂支持度＂的概念,同时设计出了相应的算法,并在此基础上,用Visual C＋＋编译出了相应的＂现代汉语兼语结构机器探测软件＂。通过对200万字的《人民日报》1998年1月语料进行机器探测试验和测试,发现：对于现...