Fatal non-accidental pediatric cranial fracture risk and three-layered cranial architecture development

This study examines the influence of three-layered cranial architecture development upon blunt force trauma (BFT) cranial outcomes associated with pediatric non-accidental injury (NAI). Macroscopic and microscopic metric and morphological comparisons of subadult crania ranging from perinatal to 17 years of age chronicle the ontogenetic development and spatial and temporal variability in the emergence of a mature cranial architecture. Cranial vault thickness increases with subadult age, accelerating in the first 2 years of life due to rapid brain growth during this period. Three-layer differentiation of the cranial tables and diploë initiates by 3–6 months but is not consistently observed until 18 months to 2 years; diploë formation is not well developed until after age 4 and does not manifest a mature appearance until after age 8. These results allow topographic documentation of cortical and diploic development and temporal and spatial variability across the growing cranium. The lateral cranial vault is identified as expressing delayed development and reduced expression of the three-layer architecture, a pattern that continues into adulthood. Comparison of fracture locations from known BFT pediatric cases with identified cranial fracture high-risk impact regions shows a concordance and suggests the presence of a higher fracture risk associated with non-accidental BFT in the lateral vault region in subadults below the age of 2. The absence or lesser development of a three-layered architecture in subadults leaves their cranial bones, particularly in the lateral vault, thin and vulnerable to the effects of BFT.     

Colonization of diatoms in and on porcine bone substrate and considerations of diatom ecology for forensic science

The presence of diatom algae in bone marrow has been used as forensic evidence of drowning for several decades; however, these studies are based on known or suspected recent drowning events. This study addresses the potential for diatoms to enter the bone marrow of skeletal remains, that is, de-fleshed long bones post-mortem. In laboratory and field experiments, bones were either inflicted with two access points by a cut and acid pitting or left intact. The bones were submerged in water for at least 1 week and up to 3 months. Samples of the bone surface and marrow were inspected for diatoms. The analysis considered the time required for diatoms to enter marrow and whether genus characteristics like size or mobility affect entry. The presence of an access point influenced diatom entry in that bones without an introduced access point had zero to one diatom present in the marrow, whereas a bone with an access point had >150 diatoms present in the marrow. The results of both laboratory and field phases suggest that diatoms will reliably colonize bone in as quickly as 1 week, establishing and maintaining communities for at least 3 months. However, the bone surface assemblages differ from the source community. Bone marrow displayed even more restrictive access to diatom colonization, resulting in communities dominated by small raphid diatoms. Based on these findings, we suggest some caveats on the use of diatoms as trace evidence in forensic science with recommendations for future avenues of research.     

“同舟共济”与适应性变革:经济增长、权力转移及中美关系

由于经济增长的差异,新兴市场日益崛起,亚太地区日益崛起,其中中国崛起尤为瞩目。纵观权力转移历史、理论与现实,中国积极寻求融入当前美国主导的国际制度安排,在战略上是正确的,中国成为这一制度的得利较多者,也是满意者和维护者。因此综合长期战略和当前金融危机冲击下的策略,除了积极推动美国对当前制度进行适应性变革外,对于美国目前的困境,中国应该量力积极帮助,共同促进全球经济早日复苏和全球善治,与美国"同舟共济"符合中国战略利益,中国需要战略规划;同时,需要面向未来,准备好美国经济复苏后的策略变化。美国凭其发达的金融业在全球财富再分配中占领制高点,金融业的发展意味着可以在财富的再分配中获得竞争优势,因此中国需要大力发展现代金融业。     

静态资源关系观及其批判

最近几十年里,关于人类资源关系的辩论越来越激烈。学者们大致形成了两个对立的流派。资源悲观主义认为,人类资源关系是零和的,一个人群消耗的资源增加了,其他群体可能得到的资源就会减少。因此,随着资源越来越匮乏,人类资源冲突会愈演愈烈。资源乐观主义认为,人类资源关系是非零和的,资源冲突能够避免。悲观主义和乐观主义尽管尖锐对立,但有共同缺陷——都是静态理论,对资源关系的解释力有限。对此,本文提出了动态的资源关系理论,能够更好地解释人类资源关系。     

When Should We Use Unit Fixed Effects Regression Models for Causal Inference with Longitudinal Data?

Many researchers use unit fixed effects regression models as their default methods for causal inference with longitudinal data. We show that the ability of these models to adjust for unobserved time‐invariant confounders comes at the expense of dynamic causal relationships, which are permitted under an alternative selection‐on‐observables approach. Using the nonparametric directed acyclic graph, we highlight two key causal identification assumptions of unit fixed effects models: Past treatments do not directly influence current outcome, and past outcomes do not affect current treatment. Furthermore, we introduce a new nonparametric matching framework that elucidates how various unit fixed effects models implicitly compare treated and control observations to draw causal inference. By establishing the equivalence between matching and weighted unit fixed effects estimators, this framework enables a diverse set of identification strategies to adjust for unobservables in the absence of dynamic causal relationships between treatment and outcome variables. We illustrate the proposed methodology through its application to the estimation of GATT membership effects on dyadic trade volume.     

Matching as Nonparametric Preprocessing for Reducing Model Dependence in Parametric Causal Inference

Kosuke Imai Department of Politics, Princeton University, Princeton, NJ 08544 e-mail: kimai{at}princeton.edu Gary King Department of Government, Harvard University, 1737 Cambridge Street, Cambridge, MA 02138 Elizabeth A. Stuart Departments of Mental Health and Biostatistics, Johns Hopkins Bloomberg School of Public Health, 624 North Broadway, Room 804, Baltimore, MD 21205 e-mail: estuart{at}jhsph.edu e-mail: king{at}harvard.edu (corresponding author) Although published works rarely include causal estimates frommore than a few model specifications, authors usually choosethe presented estimates from numerous trial runs readers neversee. Given the often large variation in estimates across choicesof control variables, functional forms, and other modeling assumptions,how can researchers ensure that the few estimates presentedare accurate or representative? How do readers know that publicationsare not merely demonstrations that it is possible to find aspecification that fits the author's favorite hypothesis? Andhow do we evaluate or even define statistical properties likeunbiasedness or mean squared error when no unique model or estimatoreven exists? Matching methods, which offer the promise of causalinference with fewer assumptions, constitute one possible wayforward, but crucial results in this fast-growing methodologicalliterature are often grossly misinterpreted. We explain howto avoid these misinterpretations and propose a unified approachthat makes it possible for researchers to preprocess data withmatching (such as with the easy-to-use software we offer) andthen to apply the best parametric techniques they would haveused anyway. This procedure makes parametric models producemore accurate and considerably less model-dependent causal inferences. Authors' note: Our thanks to Dan Carpenter and Jeff Koch fordata; Alberto Abadie, Neal Beck, Sam Cook, Alexis Diamond, BenHansen, Guido Imbens, Olivia Lau, Gabe Lenz, Paul Rosenbaum,Don Rubin, and Jas Sekhon for many helpful comments; and theNational Institutes of Aging (P01 AG17625-01), the NationalInstitute of Mental Health (MH066247), the National ScienceFoundation (SES-0318275, IIS-9874747, SES-0550873), and thePrinceton University Committee on Research in the Humanitiesand Social Sciences for research support. Software to implementthe methods in this paper is available at http://GKing.Harvard.edu/matchitand a replication data file is available as Ho et al. (2006).     

人力资源管理思想:三个里程碑及其在中国的升华

人力资源管理实践历程中三个标志性实验成果昭示了人力资源管理思想演变的客观规律,是人力资源管理思想嬗变过程中的三大里程碑。科学管理实验使人力资源管理从自发管理走向自觉管理、科学管理和制度管理;霍桑实验系统发现了提高生产效率的社会心理因素,使人力资源管理从技术管理走向社会管理、行为管理和心理管理;职业生涯实验显示员工职业发展也是现代企业管理目标,现代企业目标和员工职业发展目标共存共长。三次实验的思想脉络、理论构造、功能机制有机对接、联动传承并推向纵深,成为人力资源管理历史上三个具有划时代意义的丰碑。科学人才观提出的"以人为本"的思想和理念是人力资源管理思想在当代中国的发展和升华。     

Weapons of Mass Destruction: Major Wars,Regional Conflicts,and Terrorism

The twentieth century saw the creation and development of weapons of mass destruction (WMD): nuclear, chemical, and biological. In the following article, Ryukichi Imai, distinguished research fellow at the Institute for International Policy Studies and visiting professor at Kyorin University, Japan, describes the history of WMD and the international treaties that have been negotiated on their non-proliferation. He focuses on the history of the nuclear bomb from its first tests, to the nuclear arms race and the subsequent deterrence. He goes on to examine the issues surrounding the nuclear hot-spots of South Asia and North Korea, as well as the feasibility and effects of chemical and biological weapons. He argues that the suicide plane attacks on 11 September changed the very concept of WMD and that any future threat of a mass destruction is likely to come from terrorists beyond the reach of governments.