Stable Subsets and the Existence of a Unit in (Semi)-Prime Rings

Criteria for the existence of a unit in a semiprime, prime, or simple ring and criteria for an idempotent of an arbitrary ring or of a semiprime ring to be central are obtained. In particular, it is shown that a strictly prime ring R in which r Rr for any r R is a ring with unit. In this connection, examples of prime (and even simple) rings are presented such that r Rr rR for any r R but there is no unit. The problem of whether a given ring R has a left unit was reduced earlier by the author to the semiprime case, namely, R has a left unit if and only if r Rr for any element r of the prime radical P(R) and the ring R P(R) has a left unit.     

Asymptotically Optimal Tests and Optimal Designs for Testing the Mean in Regression Models with Applications to Change-Point Problems

Let a linear regression model be given with an experimental region [a, b] R and regression functions f ₁, ..., f _d+1 : [a, b] R. In practice it is an important question whether a certain regression function f _d+1, say, does or does not belong to the model. Therefore, we investigate the test problem H ₀ : "f _d+1 does not belong to the model" against K : "f _d+1 belong to the model" based on the least-squares residuals of the observations made at design points of the experimental region [a, b]. By a new functional central limit theorem given in Bischoff (1998, Ann. Statist. 26, 1398–1410), we are able to determine optimal tests in an asymptotic way. Moreover, we introduce the problem of experimental design for the optimal test statistics. Further, we compare the asymptotically optimal test with the likelihood ratio test (F-test) under the assumption that the error is normally distributed. Finally, we consider real change-point problems as examples and investigate by simulations the behavior of the asymptotic test for finite sample sizes. We determine optimal designs for these examples.     

光纤干涉仪中用于消除偏振衰落的平衡检测技术

针对单模光纤干涉仪两臂中光的偏振态受环境变化引起的信号衰落,提出了一种新的消偏振衰落方案.该方案基于单臂光纤干涉仪,通过对干涉仪的信号采用双路光电检测法,经过高通滤波器、平方器,将两路信号相加后,实现了干涉仪信号无偏振衰落输出.其实验结果与理论分析一致.     

基于人工传输线的小型平衡型Wilkinson功分器（英）

提出了一种基于人工传输线并采用双面平行带状线实现的小型平衡型Wilkinson功分器。该器件采用人工传输线取代传统传输线以减少电路尺寸,同时引入双面平行带状线结构用来实现功分器平衡的功能。设计的功分器尺寸仅为传统Wilkinson功分器的25%。测试结果表明,设计制作的平衡Wilkinson功分器在0.83 GHz至1.05 GHz带宽范围内相位平衡度1.28,幅度平衡度0.17 dB,回波损耗大于16.79 dB,端口隔离度大于16.21 dB。测量结果和仿真结果吻合良好,证实了该功分器具有良好的性能。     

Low‐noise,vibrational phase‐sensitive chemical imaging by balanced detection RIKE

We perform a back‐to‐back comparison between two nonlinear vibrational imaging techniques: stimulated Raman scattering (SRS) and balanced detection Raman‐induced Kerr effect (BD‐RIKE). Using a compact fiber‐based laser system for generation of pump and Stokes signals, we image polymer beads as well as human hepatocytes under the same experimental conditions. We show that BD‐RIKE, despite the slightly lower signal levels, consistently offers an improved signal‐to‐noise ratio with respect to SRS, resulting in significantly higher image quality. Importantly, we observe that such quality is not affected by the static birefringence of the sample, which makes BD‐RIKE a robust and attractive alternative to SRS. We also highlight a unique advantage of the technique, which is its capability to easily access both the real and imaginary parts of the nonlinear susceptibility, thus allowing for vibrational phase imaging. The phase information can be readily obtained from BD‐RIKE with minimal experimental effort and provides an additional chemical selectivity channel for coherent Raman microscopy. Copyright © 2014 John Wiley & Sons, Ltd.     

Hájek-Rényi-type inequality and strong law of large numbers for some dependent sequences

In this paper, we get the Hjek-Rényi-type inequalities for a pairwise NQD sequence, an Lr (r > 1) mixingale and a linear process, which have the concrete coefficients. In addition, we obtain the strong law of large numbers, strong growth rate and the integrability of supremum for the above sequences, which generalize and improve Corollary 2 for Lr (r > 1) mixingale of Hansen.     

基于第一HJ距离的线性因子模型两两比较研究

从统计意义上比较不同模型的改进效力有助于挑选出最接近金融数据生成过程的定价模型,是资产定价研究的重要课题。我们借鉴Kan和Robotti~([1])的研究成果,基于第一HJ距离构造了广义似然比检验,以台湾市场丰富的数据资料为基础,对8种常见的线性因子模型(包括基于金融资产价格的线性因子模型)进行了模型两两差异性检验。研究发现:VM和CAPM、FF3和LM这两组模型无明显差异,表明波动率冲击因子和流动性因子未带来显著的模型改进效力。由于部分定价因子可能具有共同的解释能力,VM和IVM、IVM和HSM、HSM和VanM、VanM和SkewM这多组模型间也未表现出显著的差异。同时,引入条件信息是否能改善模型效力视不同模型而定,在10%的显著性水平下,FF3、LM、VanM、SkewM的条件信息模型较无条件信息模型有所改进。     

On the existence of a cooperative solution for a coalitional game with externalities

This paper analyzes a game in coalitional form that is derived from a simple economy with multilateral externalities. Following Chander and Tulkens (1997) we assume that agents react to a blocking coalition by choosing individual best reply strategies. A non-empty core of this game is established by showing that the game is balanced. The proof relies only on standard convexity assumptions and, therefore, substantially generalizes the results in Chander and Tulkens (1997). Received June 2000/Revised version March 2001