Testing of unit roots and other fractionally integrated hypotheses in the presence of structural breaks

Tests of unit roots and other nonstationary hypotheses that were proposed by Robinson (1994) are applied in this article to the Nelson and Plosser's (1982) series. The tests can be expressed in a way allowing for structural breaks under both the null and the alternative hypotheses. When applying the tests to the same dataset as in Perron (1989), we observe that our results might be consistent with those in Perron (1989) when testing the nulls of trend-stationarity or a unit-root. However, we also observe that fractionally integrated hypotheses may be plausible alternatives in the context of structural breaks at a known period of time. Final version received: August 2000/Final version accepted: August 2001 RID="*" ID="*"  The author gratefully acknowledges the financial support from the European TMR grant No. ERBFMRX-CT-98-0213. Comments of two anonymous referees are also acknowledged.     

一台环形防喷器壳体内部缺陷的安全评价检测

利用声发射检测技术能够实时动态检测的特点,在额定工作载荷下监测环形防喷器壳体内部缺陷的动态变化,初步进行缺陷的安全评级判断。结合金属材料缺陷表面磁场变化的特征,采用金属磁记忆检测技术对防喷器壳体内部缺陷进行快速检测;最后,对应力集中区域使用超声波检测方法对缺陷进行定量、定性检测。确保防喷器缺陷的定性定量检测与分析,作为油田防喷器壳体内部缺陷的安全评价检测工艺,具有一定的借鉴价值。     

Becoming a historical thinker might be the first step for developing a consciousness of reasoned conciliation

The goal of this presentation is to examine the hypothesis that the ethno-political conflict in Israel can be utilized in history education to foster learning of historical thinking and to construct a tolerant space within the education system that will enable the structuring of in-principle criteria for coexistence prior to the ending of the conflict. I assumed that inculcation of historical knowledge in the education system in Israel by means of an attentive and reflexive cultural dialogue, which sensitively and skillfully confronts contradictory historical narratives as an everyday learning reality in class, will help structure a conciliatory consciousness of the kind we seek.     

Volatility forecasting: long memory,regime switching and heteroscedasticity

In this article, we account for the first time for long memory, regime switching and the conditional time-varying volatility of volatility (heteroscedasticity) to model and forecast market volatility using the heterogeneous autoregressive model of realized volatility (HAR-RV) and its extensions. We present several interesting and notable findings. First, existing models exhibit significant nonlinearity and clustering, which provide empirical evidence on the benefit of introducing regime switching and heteroscedasticity. Second, out-of-sample results indicate that combining regime switching and heteroscedasticity can substantially improve predictive power from a statistical viewpoint. More specifically, our proposed models generally exhibit higher forecasting accuracy. Third, these results are widely consistent across a variety of robustness tests such as different forecasting windows, forecasting models, realized measures, and stock markets. Consequently, this study sheds new light on forecasting future volatility.     

Cap and trade policies in the presence of monopoly and distortionary taxation

We extend an analytical general equilibrium model of environmental policy with pre-existing labor tax distortions to include pre-existing monopoly power as well. We show that the existence of monopoly power has two offsetting effects on welfare. First, the environmental policy reduces monopoly profits, and the negative effect on income increases labor supply in a way that partially offsets the pre-existing labor supply distortion. Second, environmental policy raises prices, so interaction with the pre-existing monopoly distortion further exacerbates the labor supply distortion. This second effect is larger, for reasonable parameter values, so the existence of monopoly reduces the welfare gain (or increases the loss) from environmental restrictions.     

组织记忆与企业家战略领导能力关系的实证研究

企业家战略领导能力是带领企业持续健康发展的重要因素之一,组织记忆是战略领导能力构建的重要源泉。文献梳理建立了组织记忆与企业家战略领导能力的理论模型与假设,实证研究表明:组织记忆对企业家战略领导能力有显著正向影响;组织记忆内容对提升企业家战略决策能力和战略控制能力的影响强于组织记忆管理水平,而企业家战略思维能力和战略实施能力的提升则更多受到组织记忆管理水平的影响。     

Trade policy under imperfect competition: The economics of Russian roulette

Summary Neo-classical economic theory shows that managed trade or protectionism is (almost) always welfare decreasing. However, measurements of the welfare costs of protectionism based on neo-classical models seem to suggest that these costs are quite small. We discuss general new insights and developments in the theory, policy and empiricism of international trade. The observation that intra-industry trade and the services sector are important has led to a shift in theory away from constant returns to scale and perfect competition towards economies of scale and scope, externalities, market imperfections, and imperfect competition. Although this, in principle, opens the door to beneficial government intervention in the economic process, we emphasize that the true costs of protection can potentially be much higher than is generally acknowledged as a result of the above mentioned shift.We would like to thank, without implicating, Martin Fase, Harry Garretsen, Catrinus Jepma, Simon Kuipers, Ger Lanjouw, Tenn Schmidt, Albert de Vaal, and Jean-Marie Viaene for stimulating conversations and useful suggestions. We thank Thijs Knaap for excellent research assistance.     

竞争对手随机进入具有随机寿命创新项目价值评估

在考虑了行业内不完全市场竞争条件下,竞争对手的随机进入及新技术随机出现对项目投资机会的价值影响,假设标的资产服从跳--扩散过程,获得了技术创新成果转化项目的投资机会的价值的模型.研究结果表明,若忽视行业中不完全市场竞争、竞争对手随机进入及新技术随机出现的影响,将会造成投资项目价值的不合理的估计.     

面向新闻领域的中文实体关系抽取

随着互联网技术的快速发展,人们能够及时地获取大量的新闻文本信息,如何从新闻中自动获取关键信息,把新闻中具有价值的信息转化为结构化数据,从而快速有效地获取有用的知识已是迫切需求。实体关系抽取是获取关键信息的方法之一,但目前关于中文的实体关系抽取工作较少。针对基于长短时记忆网络的中文实体识别模型难于提取长距离的依存关系特征和句法特征问题,提出利用双向树形长短时记忆神经网络提取依存句法树的结构特征。在提取的特征的基础上,使用条件随机场判断实体的类别和边界,并在实体识别模型中加入注意力机制提高模型的性能。在《人民日报》数据集和ACE 2005语料库上训练模型,验证了模型的有效性。     

Inked: historic African-American beach site as collective memory and group ‘Third Place’ sociability on Martha’s Vineyard

Using data gained from ethnographic research and interviews, this article examines ‘third place’ sociability in the social interactions of the Polar Bears of Martha’s Vineyard, a group of predominantly but not exclusively middle-aged and senior African-American men and women who swim, exercise and socialise together each morning at ‘the Inkwell’ beach. Using Georg Simmel’s concept of sociability and Ray Oldenburg’s third-place theoretical framework, this study explores the key role of the Monday communal breakfast and the function of conversation in establishing bonds between individuals. It further investigates the promotion of strong feelings of social connectedness, belonging, social support, social capital gains and community among its group members. The ongoing sociability and informal rules of the Polar Bears of Martha’s Vineyard has enabled it to become a model group demonstration of third-place community building. The importance of race, class and place is socio-historically investigated within the broader social context of the popular racialised section of the beach, ‘the Inkwell’, of African-American community life, and within the sub-community milieu of group social interaction.