Testing for weak-form efficiency of crude palm oil spot and future markets: new evidence from a GARCH unit root test with multiple structural breaks

There is a sizeable literature that tests for weak-form efficiency in commodity and energy spot and future prices. While many studies now allow for multiple structural breaks to address the criticism that conventional unit root tests have low power to reject the unit root null in the presence of structural change, the extant literature overlooks the fact that conventional unit root tests are biased in the presence of conditional heteroscedasticity. We apply a recently developed generalized autoregressive conditional heteroscedasticity (GARCH) unit root test with multiple structural breaks to crude palm oil spot and future prices and find much more evidence against weak-form efficiency than that found using tests that fail to allow for conditional heteroscedasticity. Our results point to the importance of allowing for heteroscedasticity when testing for efficiency in commodity and energy spot and future prices.     

The Gradual Response of Market Power to Mergers in the U.S. Steel Industry

Studies of the impact of horizontal mergers on market power typically impose an immediate adjustment of market power following a merger. This paper adopts an alternative procedure to estimate the effect of four mergers on market power in the U.S. steel industry. Namely, by estimating a switching regression model that incorporates profit-maximizing behavior, the results show that mergers generally increased market power in the steel industry. However, it did take some time for market power to fully adjust after each merger.     

Global modelling revisited

Reasons for the great impact of World Dynamics and Limits to Growth include their addressing the correct audience (the public), and the ability of systems dynamics clearly to handle and communicate information on complex and often little understood areas. Modelling projects should usually be global or national (not regional), draw heavily on mental and not just written and numerical databases, and have time horizons of perhaps 100 years. Sadly, critics of Worlds 2 and 3 have yet to come to grips with the fundamental messages presented there, although these messages are becoming increasingly vital.     

The scope of application of management accounting methods in Polish enterprises

The transformation of Poland’s economic system in the 1990s as a result of transition from a centrally planned economy to a market-based system involves significant changes in the regulatory context and in accounting practice and education.This paper presents the scope of application of management accounting concepts and methods in 60 Polish enterprises covered by a questionnaire survey carried out by the author between November 1998 and December 1999 in enterprises located in central and southern Poland. The selected companies were interviewed by means of a postal survey, with inquiry forms delivered in person in some cases.The detailed analyses carried out in this paper and the conclusions presented are also based on information obtained from documentary evidence kept by the enterprises and from direct interviews conducted in the course of work in teams engaged in analysis and assessment of cost accounting practices and in management accounting system design in a number of large and medium Polish enterprises.The empirical research carried out is aimed at verification of a number of hypotheses including the following: • modification of cost accounting systems and implementation of management accounting tools in Polish enterprises is brought about by many different factors, the most important being growth of competition and ownership changes in business entities, • Polish enterprises mostly implement the methods and techniques of operational management accounting, • short-term budgeting for cost centres is the most widely used method of management accounting.     

原型范畴理论视角下的英语时态认知解读

原型范畴理论作为认知语言学概念的基础近年来逐渐得到了语言学家的重视。原型范畴理论可以用于英语教学并对英语时态具有一定的解释力,从而为英语时态教学开辟新视角。本文以一般现在时态、一般过去时态、一般将来时态为例,探索原型范畴理论在英语时态教学中的应用。希望能推动该理论在英语时态教学中的应用。     

两种框架结构形式的转变与工程造价的对比分析

本文对采用钢结构和钢筋混凝土结构两种框架结构体系进行结构形式的转变,分析其在结构性能、结构占用面积、工期、工程造价以及综合经济效益等方面所具有的异同,对其优缺点进行分析,同时对其工程造价进行对比分析。结果显示了钢结构建筑所具有的优势,是将来厂房及高层建筑的发展趋势。     

贴钢法加固桥梁技术探讨

文章探讨了贴钢法加固桥梁的机理,提出了贴钢法加固桥梁的结构设计方法、施工工艺要点及验收办法。     

对文娱新闻未来走向的一些思考

理论界对文娱新闻的关注大多集中在对其低俗化的批判上，对其社会价值、未来发展方向等深层次的研究相对比较缺乏。本文对文娱新闻的未来发展进行了大胆的预测。文娱新闻的发展有赖于社会的进步和传媒业的发展，同时也有赖于从业人员文化素质的提高和思想水平的进步。文娱新闻包含娱乐，但并不是只有浅表化的娱乐，而是要在娱乐的同时构筑较高的文化品住，在娱乐的过程中提升文化，提高素养，这才是文娱新闻可持续发展之道。     

Tourism in the system of industrial society

Recreation and tourism are integral parts of the whole industrial social system. Viewed thus, tourism, so successful in the past two decades, seems clearly doomed to radical change. Many signs in the universe of work-habitate-leisure-travel indicate that the present system does not satisfy the human needs of traveler, host, and ultimately the social system. One inevitable result of forecast change, is a new, humane understanding of leisure and tourism; one should begin forging it before the opportunity for choice and reason disappears.     

扣件式钢管脚手架极限承载力计算模型的回顾与展望

本文回顾了近二十年来扣件式钢管脚手架的各种计算模型,并进行了对比和思考。得出了只有半刚性节点模型才真正触及了扣件连接这一本质特点,建议采用考虑了节点半刚性的框架模型进行扣件式钢管脚手架的研究和计算,同时考虑其它因素的影响。本文同时也对扣件式钢管脚手架极限承载力的进一步研究进行了展望。