彝语南部方言田房话声调研究

本文采用声学语音学的分析方法 ,使用语音分析软件“Phonolys”对彝语南部方言江城田房彝话的声调系统进行了分析 ,得出江城田房彝话的声调共有三个 ,即升调、平调和降调 ,根据语图 ,给出了它们的调值 ,并对前人研究中的偏误进行了更正     

试析创新企业规模变动的机制

企业创新是企业为更有效地利用社会经济资源而对现有资源进行新的组合或配置,其结果可以是使单位产品成本降低,也可以是使产品需求上升导致产品价格上升.在许多情况下,创新行为会使企业产品规模有扩张的倾向,但某些情况下也有可能使产出规模减少对利润最大化的追求是影响创新企业规模变动的核心因素.此外,一些非利润因素也可能抑制或扩大企业利润最大化目标所致的规模变动,并表现为放大由利润最大化所致的规模扩张,有时甚至会使企业过分偏离利润目标而丧失创新优势.     

Trend inflation,the labor market wedge,and the non-vertical Phillips curve

Recent developments in macroeconomics resurrect the view that welfare costs of inflation arise because the latter acts as a tax on money balances. Empirical contributions show that wage re-negotiations take place while expiring contracts are still in place. Bringing these seemingly unrelated aspects together in a stylized general equilibrium model, we find a disciplining effect of a positive inflation target on the wage markup and identify a long-term trade-off between inflation and output. This has important policy implications, ranging from the opportunity of revising the target in response to shocks, to the possibility of exploiting inflation as a tool to increase tax revenues via its employment-enhancing effect.     

不同荷载比下嵌固式钢框架节点M θr曲线拟合

对嵌固式节点进行有限元仿真分析，得到了嵌固式门式框架在不同的荷载工况条件下节点的M θr曲线。通过对不同荷载组合情况下得到的M θr曲线进行比较可知，节点刚度随着荷载组合的变化而变化，但两个方向框架中嵌固式节点刚度的变化规律不同。综合考虑门式框架嵌固式节点M θr曲线的特性，对多种荷载组合情况下的M θr曲线进行曲线拟合，得到拟合公式并对其进行方差分析。透过相关指数可知提出的嵌固式节点M θr曲线的拟合公式是可靠的，可为进一步深入研究嵌固式组装钢框架的力学性能提供借鉴和参考     

Modeling mortality at old age with time-varying parameters

Several models of old age mortality with time-varying parameters are expressed in a single formula. In these models, the existence of an age threshold above which mortality increases over time and below which mortality decreases over time is problematic. The conditions of appearance of this threshold are expressed and shown on logistic and exponential models with empirical data. The conditions of appearance of the threshold reflect actual situations in developed countries. Richards’ curve avoids the appearance of the threshold with empirical data.     

Comparison of different estimation methods in growth curve models for categorical data: A simulation study

This simulation study aims at investigating the performance of maximum likelihood and weighted least-square estimation approaches in growth curve models with categorical data. The goodness-of-fit indices were compared with a number of scenarios (different trajectories, sample sizes, replications, and number of categories). The results show that when the number of categories and replications are small, using weighted least-square estimating methods leads to better goodness-of-fit indices. However, when the number of categories and replications are large, both maximum likelihood and weighted least squares in estimating methods will result in similar fit indices.     

Confidence Bands for ROC Curves With Serially Dependent Data

We propose serial correlation-robust asymptotic confidence bands for the receiver operating characteristic (ROC) curve and its functional, viz., the area under ROC curve (AUC), estimated by quasi-maximum likelihood in the binormal model. Our simulation experiments confirm that this new method performs fairly well in finite samples, and confers an additional measure of robustness to nonnormality. The conventional procedure is found to be markedly undersized in terms of yielding empirical coverage probabilities lower than the nominal level, especially when the serial correlation is strong. An example from macroeconomic forecasting demonstrates the importance of accounting for serial correlation when the probability forecasts for real GDP declines are evaluated using ROC. Supplementary materials for this article are available online.     

The Effects of Family Structure on African American Adolescents' Marijuana Use

The relationship between family structure and marijuana use throughout adolescence was assessed among 1,069 African Americans from the NLSY. A model was also tested suggesting that the effects of family structure on marijuana use would be mediated by poverty, neighborhood quality, and adolescents' self‐control. As most prior studies have found, family structure was not related to female adolescents' marijuana use. For young men, being raised with both biological parents was associated with less marijuana use throughout adolescence compared to those whose mothers never married, divorced early and never remarried, or divorced and remarried. Some support for the model was also found. We concluded that being raised without the presence of a biological father is a risk factor for marijuana use among young men, but African American young women from single‐parent households have unique resources that protect them from marijuana use. Understanding those resources may offer insight into prevention programs for other youth.     

Non‐parametric interval estimation for the partial area under the ROC curve

Accurate diagnosis of disease is a critical part of health care. New diagnostic and screening tests must be evaluated based on their abilities to discriminate diseased conditions from non‐diseased conditions. For a continuous‐scale diagnostic test, a popular summary index of the receiver operating characteristic (ROC) curve is the area under the curve (AUC). However, when our focus is on a certain region of false positive rates, we often use the partial AUC instead. In this paper we have derived the asymptotic normal distribution for the non‐parametric estimator of the partial AUC with an explicit variance formula. The empirical likelihood (EL) ratio for the partial AUC is defined and it is shown that its limiting distribution is a scaled chi‐square distribution. Hybrid bootstrap and EL confidence intervals for the partial AUC are proposed by using the newly developed EL theory. We also conduct extensive simulation studies to compare the relative performance of the proposed intervals and existing intervals for the partial AUC. A real example is used to illustrate the application of the recommended intervals. The Canadian Journal of Statistics 39: 17–33; 2011 © 2011 Statistical Society of Canada     

既有线提速小半径曲线平面改造方法研究

为了满足铁路运能增加和现代经济快速发展的需求，新建铁路的同时对既有线铁路的提速改造也是非常必要的，而平面改造中小半径曲线已成为既有线提速的一个瓶颈问题。以“哈尔滨至漠河铁路扩能改造工程”加格达奇至塔河段的方案研究为例，讨论了关于既有线提速改造的设计原则及思路；结合该区段工程的设计改造过程，根据铁路的平面既有现状及特点，重点介绍了平面改造中小半径曲线的改造方法。结果表明:改造完成后的铁路平面条件能很好地满足该区段的提速要求，取得了良好的效果，为今后既有铁路提速改造提供了一定的参考。