静电电子回旋脉塞的单粒子理论

本文用单粒子理论研究了静电电子回旋脉塞。通过对静电电子回旋脉塞中的电子运动的分析,导出了电子与波互作用的非线性摆方程。文中用二阶扰动方法求解非线性摆方程,得到了TE_(mn)和TM_(mn)两种工作模式的静电电子回旋脉塞不稳定性线性增益公式,进一步证实了静电电子回旋脉塞不稳定性是存在的。     

Falling Through The Cracks: Gaps In Child Support Among Welfare Recipients

This article examines gaps in child support among welfare recipients in Wisconsin. Documented is the extent to which breakdowns at various stages—including paternity establishment, support orders, and payments—contribute to the low rate of child support receipt. Children were tracked over a 2‐year period to assess their progress through the child support system over time. Few welfare recipients are able to successfully negotiate the child support system, and mothers frequently achieve different degrees of success with different children. The characteristics of children who drop out prior to obtaining a support order suggest that, with an order in place, they would be as likely to receive support as are those children who already have orders.     

含时滞的单种群反馈控制扩散模型解的渐近行为

本文通过构造 Liapunov 泛函并结合 Smoller 不变区域理论和不等式估计方法,对含时滞的单种群反馈控制扩散模型解的渐近行为进行了讨论,获得了解的整体存在性、有界性及解的一致收敛性的若干充分条件.     

Poverty,public assistance,and children in intact and single-mother families

This article examines the effects of poverty, public assistance, and family structure on school-age children's home environment and developmental outcomes using data from the National Longitudinal Survey of Youth. The central question of this study is whether public support negatively affects school-age children's developmental outcomes, thereby contributing to the intergenerational transmission of welfare dependency. The results show that long duration and late timing of poverty have a detrimental effect on home environment and child developmental outcomes. Long duration of public assistance disturbs reading ability for children of intact families only. Late timing of public assistance actually enhances the cognitive and emotional environment and has a greater effect on the emotional environment for single-mother families. Long duration and late timing of single motherhood are detrimental to the emotional environment. Taken together, the findings suggest that the process of intergenerational transmission of welfare dependency during school-age years is primarily attributable to poverty and single motherhood rather than the duration and timing of public assistance. This study was supported in part by a William T. Grant Foundation research grant and in part by Grant No. 5-T32-HD07329-07 from the Center for Population Research, National Institute of Child Health and Human Development (NICHD), to the RAND Corporation. Her research interests include the family and public policy, particularly single mothers and their children. She received her Ph.D. from the University of Chicago in 1990.     

硅氧化物反应离子刻蚀均匀性研究(英文)

提出了提高径向刻蚀均匀性的一种新颖的方法。在反应离子刻蚀系统中,采用等离子体控制环调节硅氧化物的径向刻蚀速率,刻蚀均匀性在等效于直径为15 cm 硅片上可以达到±3%.     

试论早期希腊哲学中"一"和"多"范畴的发展

本文从逻辑和历史统一的角度,阐述了早期希腊哲学中"一"和"多"范畴的发展过程.由于早期希腊哲学家关注的主要问题是宇宙万物如何生成、如何构成的问题,所以对"一"和"多"范畴的探讨基本上是在本体论意义上展开的.虽然在早期希腊哲学中"一"和"多"的本体论意义的内涵不断拓展,但重视"一"、忽视"多"甚至割裂"一"和"多"的倾向长期存在,这个问题最终在原子论哲学中得到解决,基本实现了"一"和"多"的辩证统一.     

The portfolio choice problem: comparison of certainty equivalence and optimal Bayes portfolios

For the portfolio problem with unknown parameter values, we compare the conventional certainty equivalence portfolio choice with the optimal Bayes portfolio. In the important single risky asset case a diffuse Bayes rule leads to portfolios that differ significantly from those suggested by a certainty equivalence rule which we show are inadmissible relative to a quadratic utility function for the range of parameters we consider. These results are invariant to arbitrary changes in the utility function parameters. We illustrate the results using a simple mutual fund example.     

Recurrence relations for single and product moments of progressively Type-II censored order statistics from a generalized half-logistic distribution with application to inference

In this paper, we establish several recurrence relations for the single and product moments of progressively Type-II right-censored order statistics from a generalized half-logistic distribution. The use of these relations in a systematic recursive manner enables the computation of all the means, variances, and covariances of progressively Type-II right-censored order statistics from the generalized half-logistic distribution for all sample sizes n, effective sample sizes m, and all progressive censoring schemes (R ₁, …, R _m ). The results established here generalize the corresponding results for the usual order statistics due to Balakrishnan and Sandhu [Recurrence relations for single and product moments of order statistics from a generalized half-logistic distribution with applications to inference, J. Stat. Comput. Simul. 52 (1995), pp. 385–398.]. The moments so determined are then utilized to derive the best linear unbiased estimators of the scale and location–scale parameters of the generalized half-logistic distribution. The best linear unbiased predictors of censored failure times are discussed briefly. Finally, a numerical example is presented to illustrate the inferential method developed here.     

走出离合词现象的迷局——从准定语与准名词现象入手

词的离合现象是语法研究中的老大难问题。文章独辟蹊径,从与词的离析使用密切相关的准定语和准名词入手,根据句子的信息结构原则,解释了词的离合现象的成因。文章指出,话语的信息结构安排是促成句法结构重组的语用推力:话题语的指称化处置诱发了准定语结构的操作,基本不涉及词的离析;评述语受单一新信息原则制约而出现的事件化处置,迫使及物性低的双音词强行拆分以容纳事件化所需要素,是诱发词的离析并催生准定语和准名词的直接动因。文章的观点是,用朴素的眼光看汉语,汉语中并无什么离合词,词的离合只是非形态语中双音词的用法变异,是语用型语言句子信息结构进行整编与重组的副产品。