频率不受运放参数影响的文氏桥振荡器

本文介绍一组（12个）新的正弦振荡器，这组振荡器使用两个运算放大器，其振荡频率不受单极点有源元件增益带宽之积的影响。这种特性是由本文所介绍的电路结构取得的，即不需要调节。     

Herd on the Street: Informational Inefficiencies in a Market with Short-Term Speculation

Standard models of informed speculation suggest that traders try to learn information that others do not have. This result implicitly relies on the assumption that speculators have long horizons, i.e., can hold the asset forever. By contrast, we show that if speculators have short horizons, they may herd on the same information, trying to learn what other informed traders also know. There can be multiple herding equilibria, and herding speculators may even choose to study information that is completely unrelated to fundamentals.     

The Long Run Growth and Productivity Performance of the United Kingdom

This paper examines Britain's long run growth and productivity performance since the late nineteenth century, taking an international comparative perspective and disaggregating by sector. Britain was richer than the United States and Germany in 1870 largely because of high levels of labour productivity in services and agriculture rather than in industry, together with a highly favourable structure, particularly a small share of the labour force in agriculture. By 1990, the productivity gap in manufacturing had not grown bigger. Rather, the deterioration in Britain's overall comparative labour productivity position has been concentrated in services and agriculture, together with the effects of structural change, particularly the later shift of labour out of agriculture in the United States and Germany.     

From Planning Models to Descriptive General Equilibrium

I had known Manohar Rao for a long time. For many years I tried to lure him to join the Indira Gandhi Institute of Development Research. He always gave me his disarming smile but his loyalty to Bombay University and to his students was unshakable. He was deeply interested in improving tools for better policy analysis. Hence in this paper I raise some related issues.

     

Annuity Values in Defined Contribution Retirement Systems: Australia and Singapore Compared

Annuities promise to play an increasingly important role in countries with national defined contribution retirement systems. In this article we examine life annuities in two countries, Singapore and Australia, each of which has a national mandatory pension program. Exploiting data on annuity pricing and purchase behaviour, we compare the money's worth of life annuity products across these two nations. Our results indicate that, after controlling on administrative loadings, there are important differences in measured adverse selection. Part of the explanation may be due to the different structures of the two countries’retirement systems.     

Quality Competition and Social Welfare in Markets with Partial Coverage: New Results*

We use a vertical product differentiation model under partial market coverage to study the social welfare optimum and duopoly equilibrium when convex costs of quality provision are either fixed or variable in terms of production. We show the following new results. First, under fixed costs, the social planner charges a uniform price for the single variant that just covers costs of quality provision. Like the duopoly equilibrium, this socially optimal pricing entails a partially uncovered market, but a smaller share of the market is served compared with the duopoly equilibrium. Second, for the variable cost case, it is socially optimal to provide both high‐ and low‐quality variants, but market shares need not be equal. This differs from the result in fully covered markets. Third, in the duopoly equilibrium, the quality spread is too wide under variable costs relative to the social optimum. Under fixed costs, the duopoly produces two variants, but quality is too low relative to the social optimum, which has only one variant.     

Modeling ethical attitudes and behaviors under conditions of environmental turbulence: The case of South Africa

This study explores the impact of environmental turbulence on relationships between personal and organizational characteristics, personal values, ethical perceptions, and behavioral intentions. A causal model is tested using data obtained from a national sample of marketing research professionals in South Africa. The findings suggest turbulent conditions lead professionals to report stronger values and ethical norms, but less ethical behavioral intentions. Implications are drawn for organizations confronting growing turbulence in their external environments. A number of suggestions are made for ongoing research. Michael H. Morris became the Fletcher Jones Chair in Entrepreneurship at the University of the Pacific, Stockton, CA in 1993. He received his Ph.D. in Marketing. He is the author of two books and over forty articles in academic journals, including the Journal of International Business Studies, the Journal of Business Research, the Journal of Management, and the Journal of the Academy of Marketing Science. Dr. Morris' principal research interests include entrepreneurial behavior, industrial marketing strategy, and pricing.Amy Seidel Marks has been a Senior Lecturer in Marketing at the GSB UCT since 1989. She holds a Ph.D. in Marketing from the Kellogg Graduate School of Management, and has worked in the areas of consumer behavior analysis and social marketing for 20 years. During her time in South Africa she has conducted numerous research projects in areas such as AIDS prevention, tobacco control and iodine deficiency, and has also served as a consultant to national projects in tuberculosis drug compliance, tobacco control and adult education.Jeff Allen received his doctorate from the University of Kentucky. He is currently an Assistant Professor of Marketing at the University of Central Florida, Orlando, Florida, Dr. Allen has published in various national and international academic journals on topics of social responsibility, marketing ethics, and health care marketing. Newman S. Perry, Jr. is Professor of Management, School of Business and Public Administration at the University of the Pacific in Stockton California. He has just completed Business, Government, and Society: Managing Competitiveness, Ethics, and Social Issues published by Prentice-Hall and previously coauthored a book on strategic management.