Spatial variation in soil inorganic nitrogen across an arid urban ecosystem

We explored variations in inorganic soil nitrogen (N) concentrations across metropolitan Phoenix, Arizona, and the surrounding desert using a probability-based synoptic survey. Data were examined using spatial statistics on the entire region, as well as for the desert and urban sites separately. Concentrations of both NO₃-N and NH₄-N were markedly higher and more heterogeneous amongst urban compared to desert soils. Regional variation in soil NO₃-N concentration was best explained by latitude, land use history, population density, along with percent cover of impervious surfaces and lawn, whereas soil NH₄-N concentrations were related to only latitude and population density. Within the urban area, patterns in both soil NO₃-N and NH₄-N were best predicted by elevation, population density and type of irrigation in the surrounding neighborhood. Spatial autocorrelation of soil NO₃-N concentrations explained 49% of variation among desert sites but was absent between urban sites. We suggest that inorganic soil N concentrations are controlled by a number of ‘local’ or ‘neighborhood’ human-related drivers in the city, rather than factors related to an urban-rural gradient.     

数控机床功能的扩展

本文主要分析了HEIDENHAIN TNC 310数控铣床系统中圆弧铣削指令及螺纹铣削指令,对螺纹铣削功能进行延伸,扩展到圆弧三轴联动,并对螺纹铣削指令格式进行了修改,从而具有圆弧三轴联动铣削功能。     

Block external bootstrap in partially linear models with nonstationary strong mixing error terms

The authors extend the block external bootstrap to partially linear regression models with strongly mixing, nonstationary error terms. In addition to providing an approximate distribution for the semiparametric least square estimator of the parametric component, they propose a consistent estimator of the co‐variance matrix of this estimator.     

0-3岁婴幼儿亲子阅读中亲子互动策略优化的行动研究

基于 0-3 岁婴幼儿亲子阅读互动现状调查发现的家长互动经验缺乏、形式单一等问题,开展“计划—行动—观察—反思—再计划”三轮亲子阅读互动循环提升的行动研究。实践表明,创设情境多元互动、拓展经验促成互动、审美体验美化互动是提升阅读互动质量的有效策略;家长对婴幼儿身心发展特点和教育规律的认知、对美的鉴赏与表达能力是影响互动策略实施的重要因素;专家的精心指导和及时评价、家庭间的作品展示和体会交流是营造阅读互动氛围提升互动效果的良好举措。建议家长自主学习、积极实践、主动交流来推进有效互动策略的实施。     

政府绩效评估指标体系中文文献评述:基于"3Es"的逻辑框架

从20世纪90年代以来,我国学者对政府绩效评估进行了很多的理论研究,但其中明确建立了指标体系的研究成果并不太多。本文基于"3Es"的逻辑框架,用政府服务的三个流程:投入、产出、结果为分析维度,从国内742篇相关文献中选择其中建立了绩效评估指标的42篇文章对指标进行了归类分解和评述。     

The governance of social enterprises: Mission drift and accountability challenges in hybrid organizations

We examine the challenges of governance facing organizations that pursue a social mission through the use of market mechanisms. These hybrid organizations, often referred to as social enterprises, combine aspects of both charity and business at their core. In this paper we distinguish between two ideal types of such hybrids, differentiated and integrated, and we conceptualize two key challenges of governance they face: accountability for dual performance objectives and accountability to multiple principal stakeholders. We revisit the potential and limitations of recently introduced legal forms to address these challenges. We then theorize about the importance of organizational governance and the role of governing boards in particular, in prioritizing and aligning potentially conflicting objectives and interests in order to avoid mission drift and to maintain organizational hybridity in social enterprises. Finally, we discuss future research directions and the implications of this work for rethinking traditional categories of organizations, namely business and charity.     

Variance estimation based on blocked 3×2 cross-validation in high-dimensional linear regression

In high-dimensional linear regression, the dimension of variables is always greater than the sample size. In this situation, the traditional variance estimation technique based on ordinary least squares constantly exhibits a high bias even under sparsity assumption. One of the major reasons is the high spurious correlation between unobserved realized noise and several predictors. To alleviate this problem, a refitted cross-validation (RCV) method has been proposed in the literature. However, for a complicated model, the RCV exhibits a lower probability that the selected model includes the true model in case of finite samples. This phenomenon may easily result in a large bias of variance estimation. Thus, a model selection method based on the ranks of the frequency of occurrences in six votes from a blocked 3×2 cross-validation is proposed in this study. The proposed method has a considerably larger probability of including the true model in practice than the RCV method. The variance estimation obtained using the model selected by the proposed method also shows a lower bias and a smaller variance. Furthermore, theoretical analysis proves the asymptotic normality property of the proposed variance estimation.     

A general central limit theorem and a subsampling variance estimator for α‐mixing point processes

We establish a central limit theorem for multivariate summary statistics of nonstationary α‐mixing spatial point processes and a subsampling estimator of the covariance matrix of such statistics. The central limit theorem is crucial for establishing asymptotic properties of estimators in statistics for spatial point processes. The covariance matrix subsampling estimator is flexible and model free. It is needed, for example, to construct confidence intervals and ellipsoids based on asymptotic normality of estimators. We also provide a simulation study investigating an application of our results to estimating functions.     

On a control chart for the Gini index with simulations

In this work we suggest the use of the Gini index on control charts. The asymptotic properties of Gini index are presented and the control charts based on appropriate confidence intervals are constructed. The suitability of the proposed charts are investigated by means of extensive simulations.     

Social health protection in Cambodia: Challenges of policy design and implementation

The Government of Cambodia is implementing ambitious reform initiatives to improve the country's social health protection system. In January 2018, it was announced that the Health Equity Fund (HEF), which is fully subsidized by a joint government‐donor initiative for the reimbursement of user fees for the poor at public health facilities, is to be expanded to some segments of informal workers belonging to associations, as well as to commune and village chiefs. Since 2017, the National Social Security Fund (NSSF) has provided social health insurance for formal economy workers in enterprises with eight employees or more. In January 2018, it was expanded to civil servants and all employees regardless of the size of the enterprise. However, this article highlights that the new ambitious reforms are not accompanied by careful planning as regards funding, service delivery, human resources and institutional design. This article therefore aims to examine key policy issues and challenges for Cambodia's ambitious reform of its social health protection system in terms of resource generation, population coverage, strategic purchasing and governance.