关于Liouville定理的注记

Liouville定理在复分析中十分重要,本文来用二种新法予以证明,并对它作适当推广。     

变时滞控制系統的镇定性

本文首先建立一个变系数变时滞微分不等式。然后,利用此微分分等式研究具有变量时滞的控制系统的镇定问题,获得了判别系统镇定的简便充不了,准则。     

Race and Loss of Privilege: African American/White Differences in the Determinants of Job Layoffs From Upper-Tier Occupations

Data from the Panel Study of Income Dynamics supports predictions from the minority vulnerability thesis concerning the determinants of job layoffs among African Americans and Whites who work in upper-middle-class occupations. Specifically, after controlling for seniority, layoffs for African Americans are relatively unstructured by traditional stratification-based causal factors, namely, background socioeconomic status, human-capital credentials, and job/labor market characteristics. Analyses also indicate that racial differences in the determinants of layoffs are more pronounced in nonservice-based than service-based firms in the private sector and in the private sector relative to the public sector.     

Redistribution and labour supply

This paper explores the effect of personal income taxes on redistribution when labour supply reactions are taken into consideration. The results indicate that the classical non-behavioural results on redistribution are not necessarily satisfied in a more general behavioural framework. In this respect, it is shown that the relevant transition to measure redistribution is not the transition from the initial post-tax to the final post-tax income distribution, but rather from the more precise initial pre-tax to the final post-tax income distribution. In addition, the necessary and sufficient conditions to ensure redistribution in this wider setting are postulated, which helps determine the behavioural bias under alternative tax and labour supply models. This shows that the functional specification of labour supply may also affect the results.     

具有网络外部性的扩展Hotelling模型

将网络外部性引入线性运输成本下的Hotelling模型,研究了两家网络产品厂商首先选址,然后进行价格竞争的两阶段完全信息动态博弈问题,得到了厂商价格竞争均衡的存在性条件,推广了一般Hotelling模型的结论.由于网络外部性的存在,消费者效用是相互依赖的.网络产品的市场份额既是消费者选择的结果,又是消费者选择的依据.文章将交通流量分配技术和无穷维变分方法相结合,建立了刻画网络产品市场划分的模型——无穷维变分不等式,并研究了市场划分的存在性和唯一性问题.最后假定厂商定位在两端,分析了产品的网络外部性特征及单位运输成本对两个厂商竞争均衡情况的影响.     

Nonparametric confidence and tolerance intervals from record values data

In a number of situations only observations that exceed or only those that fall below the current extreme value are recorded. Examples include meteorology, hydrology, athletic events and mining. Industrial stress testing is also an example in which only items that are weaker than all the observed items are destroyed. In this paper, it is shown that, how record values can be used to provide distribution-free confidence intervals for population quantiles and tolerance intervals. We provide some tables that help one choose the appropriate record values and present a numerical example. Also universal upper bounds for the expectation of the length of the confidence intervals are derived. The results may be of interest in situation where only record values are stored.     

凸函数的一个定义及分析中的九个不等式

本文从凸函数的一个定义出发,得到了几个重要不等式,进而解决了一些不等式的证明。     

Spatial inequality and poverty among American children

National-level statistics often mask extreme spatial differentiation in child poverty. Using county-level data from the 1990 US decennial census summary tape file, we show that child poverty is distributed unevenly over geographic space. Child poverty is concentrated in counties in Appalachia, the Mississippi Delta, and the southern black belt. Child poverty rates are strongly influenced by the local industrial composition (e.g., agriculture and manufacturing), but the effects are largely indirect, operating primarily through reduced employment opportunities among adult workers. High county unemployment and underemployment rates contribute directly to children's economic deprivation, as well as indirectly by undermining the formation and stability of two-parent families. Our results highlight existing spatial differentiation and inequality in children's economic well-being, and provide a point of departure for additional research on the geography of child poverty.     

Conditional MSE-based discrimination of the sample mean and the post-stratification estimator in population sampling

Whenever a random sample is drawn from a stratified population, the post-stratification estimator $\tilde X$ usually is preferred to the sample mean $\tilde X$ , when the population mean is to be estimated. This is due to the fact that the variance of $\tilde X$ is asymptotically smaller than that of $\tilde X$ , while both estimators are asymptotically unbiased. However, this only holds looking at post-stratification unconditionally, when strata sample sizes are random. Conditioned on the realized sample sizes, the MSE of $\tilde X$ can be higher than that of $\tilde X$ which means that $\tilde X$ should be preferred to $\tilde X$ , even if it is biased. The conditional MSE difference of $\tilde X$ and $\tilde X$ is estimated, and using this estimation and its variance a heuristic test based on the Vysochanskiî-Petunin inequality is derived.     

Culture,Race, and the Economic Assimilation of Immigrants

The economic assimilation of European-origin immigrants is fairly rapid but selectively culture contingent; the economic assimilation of racial minority immigrants is less rapid and less culture contingent. Regression analysis of survey data examines occupational status and earnings effects of eight ethnic attachments among men and women in seven ethnic and racial minorities in mainstream and enclave employment in Toronto (N = 1792), controlling for foreign and domestically acquired human capital. Assimilationist pressures that the survey showed to be widely perceived may apply more to Europeans than to racial minorities. Economic assimilation is affected when foreignness is most pronounced: very selectively for European immigrants and universally for racial minorities treated as foreign, presumably based on skin color, regardless of specific culture, identity, behaviors, or network affiliations.