A Conversation with Yuan Shih Chow

Yuan Shih Chow was born in Hubei province in China, on September 1, 1924. The eldest child of a local militia and political leader, he grew up in war and turmoil. His hometown was on the front line during most of the Japanese invasion and occupation of China. When he was 16, Y. S. Chow journeyed, mostly on foot, to Chongqing (Chung-King), the wartime Chinese capital, to finish his high school education. When the Communist party gained power in China, Y. S. Chow had already followed his university job to Taiwan. In Taiwan, he taught mathematics as an assistant at National Taiwan University until he came to the United States in 1954. At the University of Illinois, he studied under J. L. Doob and received his Ph.D. in 1958. He served as a staff mathematician and adjunct faculty at the IBM Watson Research Laboratory and Columbia University from 1959 to 1962. He was a member of the Statistics Department at Purdue University from 1962 to 1968. From 1968 until his retirement in 1993, Y. S. Chow served as Professor of Mathematical Statistics at Columbia University. At different times, he was a visiting professor at the University of California at Berkeley, University of Heidelberg (Germany) and the National Central University, Taiwan. He served as Director of the Institute of Mathematics of Academia Sinica, Taiwan, and Director of the Center of Applied Statistics at Nankai University, Tianjin, China. He was instrumental in establishing the Institute of Statistics of Academia Sinica in Taiwan. He is currently Professor Emeritus at Columbia University. Y. S. Chow is a fellow of the Institute of Mathematical Statistics, a member of the International Statistical Institute and a member of Taiwan's Academia Sinica. He has numerous publications, including Great Expectations: The Theory of Optimal Stopping (1971), in collaboration with Herbert Robbins and David Siegmund, and Probability Theory (1978), in collaboration with Henry Teicher. Y. S. Chow has a strong interest in mathematics education. He taught high school mathematics for one year in 1947 and wrote a book on high school algebra in collaboration with J. H. Teng and M. L. Chu. In 1992, Y. S. Chow, together with I. S. Chang and W. C. Ho, established the Chinese Institute of Probability and Statistics in Taiwan. This conversation took place in the fall of 2003 in Dobbs Ferry, New York.Comment: Published at http://dx.doi.org/10.1214/088342304000000224 in the Statistical Science (http://www.imstat.org/sts/) by the Institute of Mathematical Statistics (http://www.imstat.org

Atomic Mechanism and Criterion for Hydrogen-Induced Transgranular to Intergranular Fracture Transition

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Unfolding-model-based visualization: theory, method and applications

Multidimensional unfolding methods are widely used for visualizing item response data. Such methods project respondents and items simultaneously onto a low-dimensional Euclidian space, in which respondents and items are represented by ideal points, with personperson, item-item, and person-item similarities being captured by the Euclidian distances between the points. In this paper, we study the visualization of multidimensional unfolding from a statistical perspective. We cast multidimensional unfolding into an estimation problem, where the respondent and item ideal points are treated as parameters to be estimated. An estimator is then proposed for the simultaneous estimation of these parameters. Asymptotic theory is provided for the recovery of the ideal points, shedding lights on the validity of model-based visualization. An alternating projected gradient descent algorithm is proposed for the parameter estimation. We provide two illustrative examples, one on users’ movie rating and the other on senate roll call voting

Vibration measurement in a metro depot with trains running in the top story

Metro depots are places for subway train to get parked and maintained. To avoid the waste of large city areas occupied by depots, there is a need of developing depots for commercial and/or residential use as well, and in that case the train-induced vibrations become the major concern. This paper presents a unique case study on the vibration measurement in a 3-story metro depot, where the first two stories are developed for offices and shops and the third story is used as the maintenance garage with trains moving in/out through the connecting viaducts. Acceleration time histories of rails and floors in the three stories were measured. Amplitudes and frequency contents of the vibrations at different locations are compared through the corresponding frequency spectra and 1/3 octave band root-mean-square (RMS) spectra. The influence of track positions on floor vibration is investigated, and the vibration level of the building is evaluated using two indicators. Finally, numerical simulation is carried out so as to provide some references to the vibration control