Modeling the impact of supra-structural network nodes: The case of anonymous syringe sharing and HIV among people who inject drugs

Networks are well understood as crucial to the diffusion of HIV among injection drug users (IDUs), but quasi-anonymous risk nodes - such as shooting galleries - resist measurement and incorporation into empirical analyses of disease diffusion. Drawing on network data from 767 IDUs in Bushwick, Brooklyn, we illustrate the use of calibrated agent-based models (CABMs) to account for network structure, injection practices, and quasi-anonymous transmission in shooting galleries. Results confirm the importance of network structure and actor heterogeneity to the magnitude and speed of HIV transmission. Models further demonstrate that quasi-anonymous injections in shooting galleries increase the speed of HIV diffusion across the whole network and have the greatest impact on HIV seroconversion levels for IDUs at the network periphery. Shooting galleries are shown to be transmission hubs that operate independently of traceable structural ties, linking otherwise unconnected network components. CABMs potentially increase understandings of HIV diffusion dynamics by infusing computer simulations with empirical data.     

The source of Black-White inequality in early language acquisition: Evidence from Early Head Start

I compare language learning trajectories for Black and White children over the first 3 years of life using data from the Early Head Start Research and Evaluation study (EHSRE) in order to determine the timing and source of divergence in early language skill. Results indicate that that while controlling for racial differences in family background and a measure of the home language environment cannot entirely account for disparities in language acquisition, interactions between age, race and maternal education, and between race and a time-varying measure of the home language environment play a significant role. I show that returns to parental education and the home language environment, in terms of language learning, are higher for White children than their Black peers. Specification checks confirm that these results are robust to alternate definitions of child language and the home language environment, and that no interactions between race, age and any of the other covariates are significant. I discuss possible explanations for these race specific education gradients, including measurement error and test bias. In addition, I address relevant empirical issues in estimating language growth with respect to linguistic inputs and the home language environment.     

我国财政赤字和货币供应量联动性的实证模型分析

近期以来国际金融危机的加深,进一步揭示了一国财政赤字与宏观经济之间的深刻关联。进入新世纪以来,我国运用财政赤字的手段和方法不断改进,对于我们应对国际金融市场的动荡、促进内需和经济增长起到了很大作用。但同时,财政赤字与货币发行量之间不可调和的正向关系,也给我国经济体系带来了一定的隐患。因此,通过理论梳理与实证分析来理清赤字规模和货币供应量之间的关系,有助于我们今后宏观经济管理手段和金融市场监管能力的提升。     

对“公司＋农户”组织模式的反思

本文对当前我国“公司＋农户”组织模式困境作了较为深入的剖析。一是对公司和农户签订的契约环境进行分析,找出“公司＋农户”组织困境产生的根源。二是对履约过程中的障碍进行分析,找出“公司＋农户”组织运行的困境。结合我国实际提出了“公司＋农户”组织模式改进的建议：通过提高农户的组织化程度,构建有效的治理结构,摆脱集体行动逻辑的困境;扩大农户生产规模,提高自我履约能力;双方建立起真正的利益共享机制;政府体制进行改进和互补性制度的安排。     

MAP segmentation in Bayesian hidden Markov models: a case study

We consider the problem of estimating the maximum posterior probability (MAP) state sequence for a finite state and finite emission alphabet hidden Markov model (HMM) in the Bayesian setup, where both emission and transition matrices have Dirichlet priors. We study a training set consisting of thousands of protein alignment pairs. The training data is used to set the prior hyperparameters for Bayesian MAP segmentation. Since the Viterbi algorithm is not applicable any more, there is no simple procedure to find the MAP path, and several iterative algorithms are considered and compared. The main goal of the paper is to test the Bayesian setup against the frequentist one, where the parameters of HMM are estimated using the training data.     

西方社会的邪教控制模式及其文化分析

西方社会允许邪教合法存在、但依法监控其活动以防范邪教犯罪行为发生的邪教控制模式是西方社会特定的宗教文化、政治文化和法律文化的产物。从文化的角度看,这种模式既有其合理的一面,又有着致命的缺陷。西方社会对这种缺陷进行了文化上的检讨,但由于自由主义文化内在的缺陷使得已有的检讨不彻底,也无法为更有效地建立反邪教模式提供文化上的支持。     

阅读个性与个性化阅读教学模式

英语教学的核心是培养学生的思维能力,而思维能力的最高层次是创造思维.为此,要通过个性化阅读教学,发挥学生更大的积极性和主观能动性,培养学生的阅读个性和创造思维,从而提高阅读能力.个性化阅读教学主要有两种模式:探索型模式与自主型模式.     

经贸类专业课"辩论赛"教学模式探讨

根据当今社会对人才培养的新要求和素质教育思想,针对专业课程教学中传统教学模式的不足,探讨在经贸类专业课教学中导入“辩论赛”机制的创新教学模式,认为该教学模式体现了学生主体性和素质教育的原则,符合新时代对广大大学生的要求,具有较好的实践效果。     

基于项目作业训练的教学模式

根据创造性教学的原理,探讨将项目作业训练渗透到高等教育教学活动的各个环节,使学生在教师的指导下,综合各学科知识,借助多种资源,通过实施一个完整的项目,在解决问题和制作产品过程中,自主完成知识建构和能力提高,从而培养学生的自学能力、创新能力、动手能力以及提出问题并解决问题的能力。