Space-time Multi Type Log Gaussian Cox Processes with a View to Modelling Weeds

Log Gaussian Cox processes as introduced in Moller et al. (1998) are extended to space-time models called log Gaussian Cox birth processes. These processes allow modelling of spatial and temporal heterogeneity in time series of increasing point processes consisting of different types of points. The models are shown to be easy to analyse yet flexible enough for a detailed statistical analysis of a particular agricultural experiment concerning the development of two weed species on an organic barley field. Particularly, the aspects of estimation, model validation and intensity surface prediction are discussed.     

机床导轨液压爬行的原因及解决措施

分析了机床导轨爬行运动的危害 ,产生爬行运动的原因及解决措施     

Mapping quantitative trait loci using both extremely discordant and concordant sib pairs: a unified approach for meta-analysis

Extremely discordant (ED) and concordant (EC) sib pairs are recommended by Risch and Zhang ( 1995, 1996 ) and Zhang and Risch ( 1996 ) for the detection of linkage on the basis of power analysis. They did not, however, include both discordant and concordant sib pairs simultaneously in the test statistic. We construct a new test statistic including both types of sib pairs. The size of the sample needed to identify the sib pairs and parents, who will be genotyped, is reduced substantially by including a hybrid of discordant and concordant sib pairs in the analysis. This mixed design also provides a common parameter that simplifies meta-analysis of sib pair linkage studies.     

An Equivalence of Conditional and Unconditional Maximum Likelihood Estimators via Infinite Replication of Observations

Motivated by an application with complex survey data, we show that for logistic regression with a simple matched-pairs design, infinitely replicating observations and maximizing the conditional likelihood results in an estimator exactly identical to the unconditional maximum likelihood estimator based on the original sample, which is inconsistent. Therefore, applying conditional likelihood methods to a pseudosample with observations replicated a large number of times can lead to an inconsistent estimator; this casts doubt on one possible approach to conditional logistic regression with complex survey data. We speculate that for more general designs, an asymptotic equivalence holds.     

Becoming independent through au pair migration: self-making and social re-positioning among young Filipinas in Denmark

Over the past decade, growing numbers of young Filipinas have entered Denmark on the au pair scheme. While its official aim is to broaden the cultural horizons of youth, researchers generally view Filipina au pairing as a form of labour migration using au pairs as inexpensive domestic workers. This article argues that, despite this critique, au pairing does play an important formative role for young Filipinas because it opens up for experiences abroad that enable them to be recognised as independent adults in Philippine society. Rather than autonomy, however, au pairs define their independence in terms of their capacity to assume responsibility for others, thereby achieving a position of social respect. Based on ethnographic fieldwork in Denmark and the Philippines, this article explores how young Filipinas use the social, economic, and cultural resources they gain from their au pair stay abroad to re-position themselves vis-à-vis family and friends at home.     

Examination and visualisation of the simplifying assumption for vine copulas in three dimensions

Vine copulas are a highly flexible class of dependence models, which are based on the decomposition of the density into bivariate building blocks. For applications one usually makes the simplifying assumption that copulas of conditional distributions are independent of the variables on which they are conditioned. However this assumption has been criticised for being too restrictive. We examine both simplified and non‐simplified vine copulas in three dimensions and investigate conceptual differences. We show and compare contour surfaces of three‐dimensional vine copula models, which prove to be much more informative than the contour lines of the bivariate marginals. Our investigation shows that non‐simplified vine copulas can exhibit arbitrarily irregular shapes, whereas simplified vine copulas appear to be smooth extrapolations of their bivariate margins to three dimensions. In addition to a variety of constructed examples, we also investigate a three‐dimensional subset of the well‐known uranium data set and visually detect the fact that a non‐simplified vine copula is necessary to capture its complex dependence structure.     

重大突发公共卫生事件社会脆弱性评价及障碍因素分析

文章构建了重大突发公共卫生事件社会脆弱性评价指标体系,利用自然断点法将脆弱性按照由低到高分为Ⅰ—Ⅳ四个等级,以湖南省为例运用区间数—集对分析法、熵权法对湖南14个市州的社会脆弱性等级进行了评价,并采用障碍度模型分析了湖南省社会脆弱性的主要障碍因素。研究表明：长沙市和湘西自治州的社会脆弱性等级为Ⅰ级,株洲、湘潭、岳阳、常德、永州评价等级为Ⅱ级,社会脆弱性评价等级为Ⅲ级的是衡阳、邵阳、益阳、郴州、怀化和娄底,张家界的社会脆弱性最高,为Ⅳ级。不同市州社会脆弱性的主要来源以及降低脆弱性的有利因素因各地区人口、经济、卫生资源和政府防控等不同维度的发展差异而不尽相同。就湖南整体而言,人口、经济、卫生体系和政府防控各维度指标均对社会脆弱性存在影响,其中人口和经济因素的影响更大。     

含有移动副的平面四连杆机构的类型分析

本文对常用的含有移动副的平面四连杆机构进行了类型分析,并分析了主动件和从动件的运动范围。     

T1-1223超导体的额外氧效应

结合有效价键模型和原子对势的理论计算研究了T1-1223超导相的Cu-O金字塔五配位上由于Fe掺杂所导致的额外氧效应．研究结果表明：Fe掺杂原子占据Cu晶位后．将导致额外氧进入晶格而占据Ca原子四方网络的间隙位置．Fe掺杂所带来的额外氧。对Cu-O面载流子有很大的局域化作用．导致了载流子浓度降低，同时破坏了Cu-O平面的完整性．也致使Tc下降。这一点得到了超导电性测量的证实．     

Learning from experience or learning from others?: Inferring informal training from a human capital earnings function with matched employer–employee data

A model of informal training which combines learning from own experience and learning from others is proposed in this paper. It yields a closed-form solution that revises Mincer–Jovanovic's [Mincer, J., Jovanovic, B., 1981. Labor mobility and wages. In: Rosen, S. (Ed.), Studies in Labor Markets. Chicago University Press, Chicago, pp. 21–64] treatment of tenure in the human capital earnings function. We estimate the structural parameters of this non-linear model on a large French cross-section with matched employer–employee data. We find that workers on average can learn from others 10% of their own human capital on entering one plant, and catch half of their learning from others’ potential in just 2 years. The private marginal returns to education are declining with education as more educated workers have less to learn from others and share the social returns of their own education with their less qualified co-workers. The potential for learning from others on the job varies across jobs and establishments, and this provides a new distinction between imitation jobs and experience jobs. Workers in imitation jobs, who learn most from others, tend to have considerably longer tenure than workers in experience jobs. Although workers in experience jobs can learn little from others, we find that they learn a lot by themselves. We document several analogies between the imitation jobs/experience jobs “dualism” and the primary/secondary jobs and firms’ dualism implied by the dual labor market theory. However, our binary classification of jobs depicts the data more closely than the dual theory categorization into primary-type and secondary-type establishments. Competition prevails between jobs and firms but jobs differ by their learning technology.