Are services to prevent foster care effective?

The prevention of foster care became an important issue for child welfare services during the 1970s. Two main types of prevention models have emerged: crisis intervention programs intended to prevent imminent placement and intensive service programs designed to avert those crisis situations that precipitate placement. A critical analysis of several project evaluations leads to the conclusion that neither model has been markedly successful. Low nominal project placement rates seem attributable to inability to predict placements and to client selection biases. From a strictly financial perspective, preventive services have been considerably more expensive than regular services, including temporary family foster care. Data from a new demonstration project in New Jersey illustrate various problems in providing and evaluating preventive services to families referred to protective service agencies. Implications of the findings for prevention programs and policies are discussed, and a new direction focused on truly early intervention with children and families is proposed.     

基于自相关理论的GM(1,1)和GM(1,N)联合预测

通过引入自相关分析，将GM（1，1）与GM（1，N）两者的优点有机结合，运用GM（1，1）预测模型所需的数据量，达到GM（1，N）预测模型所具有的预测精度，减少灰色模型的预测误差。     

继承与创新：沃尔兹新现实主义理论定位再探讨

肯尼思·沃尔兹的新现实主义是国际政治研究的里程碑,但学界对这一里程碑含义的理解可能存在偏差。这一理论不是国际政治研究科学化的起点,而是对古典现实主义核心论点的历史性再诠释。沃尔兹和其他古典现实主义者一样认为人的理性能力存在限度,相信实力对比是进行利益划分的客观依据,劝告政治家遵行责任伦理。古典现实主义者与沃尔兹之间的差异并没有想象的大,古典现实主义者也强调安全,他们发现国际政治中存在着安全困境,追求过多权力会导致不安全,国家追求权力应适可而止。古典现实主义者还发现世界政治中因果关系非常复杂,事件的结果绝少和当事者的动机一致,“事与愿违”是政治中的常态,这与沃尔兹强调的“系统效应”相似。新古典现实主义者试图将沃尔兹的理论进一步科学化,他们希望结合结构变量与单元变量,提出更科学的理论解释、预测国家的行为,这不仅误解了沃尔兹,也背离了现实主义传统。     

脐橙氮、磷矿质营养的运转分配规律和座果机制的研究

本试验选择朋娜脐橙（Skagg’sBonanzaNavel）,在萌芽期和花芽分化期叶片施用15N硫铵,(32)P磷酸二氢纳和(15)N尿素,研究脐橙在萌芽期、初花期、生理落果期以及花芽分化期氮、磷营养吸收运转分配规律．结果表明开花这个生理过程需消耗大量氮、磷营养．同时在落花落果期,落花落果的(32)P放射比强度和NDFF％都比座果的小,说明,氮磷营养条件是引起脐橙落花落果的主要原因之一．而且,GA3＋BA,GA3激素处理能吸引氮磷营养向幼果运输,此结果与GA3＋BA,GA3处理提高座果率和减少落果率相一致．     

微乳液聚合制备聚丙烯酰胺及聚N-异丙基丙烯酰胺超细微粒

研究了琥珀酸双（２－乙基己酯）磺酸钠（ＡＯＴ）、甲苯（Ｔ）、乙酰胺（ＥＭ）、丙烯酰胺（ＡＭ）、Ｎ－异丙基丙烯酰胺（ＮＩＰＡＭ）、Ｎ,Ｎ－亚甲基双丙烯酰胺（ＢＩＳ）、水组成的六种微乳液体系,以电导法和目视法测定了其相区临界点电导率,并绘制了各自的拟三元相图;以偶氮二异丁腈（ＡＩＢＮ）为引发剂,在微乳液中制备了聚丙烯酰胺及聚Ｎ－异丙基丙烯酰胺超细微粒．用ＩＲ谱对其进行了验证,以扫描电镜观察了其外部结构特征,测得微粒平均粒径为０．０５～０．１０μｍ．实验表明,可在微乳液中制备ＰＡＭ及ＰＮＩＰＡＭ超细微粒．     

The Singularity of the Information Matrix of the Mixed Proportional Hazard Model

This paper presents new identification conditions for the mixed proportional hazard model. In particular, the baseline hazard is assumed to be bounded away from 0 and ∞ near t = 0. These conditions ensure that the information matrix is nonsingular. The paper also presents an estimator for the mixed proportional hazard model that converges at rate N^−1/2.     

城市外来务工人员的工作和居住环境及其健康效应——以深圳为例

20世纪80年代以来,我国快速的人口流动与事实城市化对城市环境与人口健康提出了严峻的挑战。本研究通过在深圳市开展的调查,分析了城市外来务工人员的工作、生活环境特征与身心健康状况,初步检验了环境因素对外来务工人员身心健康的净效应。研究发现,相对于其他社会经济因素而言,居住环境和工作环境对外来务工人员的健康具有更为突出的影响。改善外来务工人员的工作和居住环境、倡导良好的保健行为和生活习惯,对于改善其健康状况具有重要意义。     

莫斯科国际金融中心建设前景透析

2008年5月,俄罗斯正式提出到2025年把莫斯科建成国际金融中心的目标.围绕着莫斯科能否如期建成国际金融中心的争论也随之而起.平心而论,无论从政府的决心和作用,还是良好的经济增长基础和潜力看,俄罗斯的确在某些方面具有建设国际金融中心的有利条件.但是国际金融中心的建成是"合力" 的结果.而从目前看,俄罗斯还存在许多不利于 "合力"成长的因素.莫斯科能否如期建成国际金融中心,关键要看俄罗斯能否利用"后金融危机"环境,改变传统的 "赶超战略"思维和"重增长轻结构"的惯性发展模式,通过改革垄断行业,逐步医治"经济结构病",全方位地深化金融市场基础设施的"软件"和"硬件"建设,不断培育国际金融中心发展的底蕴.     

“A＋N”的认知研究

文章从认知语言学的角度出发,对＂A＋N＂结构进行全面的考察,包括原型理论、构式、隐喻、成分意义等。指出＂,A＋N＂结构从一个侧面反映了人类认知的体验基础,以及认知遵循的从简单到复杂、从客观到主观的基本规律,而隐喻则是人类认识不断深化的重要机制之一。隐喻具有突破语义限制的作用,其产生的结果可使＂A＋N＂的意义固化,从而形成习语和惯用语。     

Nonparametric covariate adjustment for receiver operating characteristic curves

The accuracy of a diagnostic test is typically characterized using the receiver operating characteristic (ROC) curve. Summarizing indexes such as the area under the ROC curve (AUC) are used to compare different tests as well as to measure the difference between two populations. Often additional information is available on some of the covariates which are known to influence the accuracy of such measures. The authors propose nonparametric methods for covariate adjustment of the AUC. Models with normal errors and possibly non‐normal errors are discussed and analyzed separately. Nonparametric regression is used for estimating mean and variance functions in both scenarios. In the model that relaxes the assumption of normality, the authors propose a covariate‐adjusted Mann–Whitney estimator for AUC estimation which effectively uses available data to construct working samples at any covariate value of interest and is computationally efficient for implementation. This provides a generalization of the Mann–Whitney approach for comparing two populations by taking covariate effects into account. The authors derive asymptotic properties for the AUC estimators in both settings, including asymptotic normality, optimal strong uniform convergence rates and mean squared error (MSE) consistency. The MSE of the AUC estimators was also assessed in smaller samples by simulation. Data from an agricultural study were used to illustrate the methods of analysis. The Canadian Journal of Statistics 38:27–46; 2010 © 2009 Statistical Society of Canada