Optimal investment with vintage capital: Equilibrium distributions

The paper concerns the study of equilibrium points, or steady states, of economic systems arising in modeling optimal investment with vintage capital, namely, systems where all key variables (capitals, investments, prices) are indexed not only by time but also by age. Capital accumulation is hence described as a partial differential equation (briefly, PDE), and equilibrium points are in fact equilibrium distributions in the variable of ages. A general method is developed to compute and study equilibrium points of a wide range of infinite dimensional, infinite horizon, optimal control problems. We apply the method to optimal investment with vintage capital, for a variety of data, deriving existence and uniqueness of equilibrium distribution, as well as analytic formulas for optimal controls and trajectories in the long run. The examples suggest that the same method can be applied to other economic problems displaying heterogeneity. This shows how effective the theoretical machinery of optimal control in infinite dimension is in computing explicitly equilibrium distributions. To this extent, the results of this work constitute a first crucial step towards a thorough understanding of the behavior of optimal paths in the long run.     

Retaining and engaging older workers: A solution to worker shortages in the U.S.

Over the next 20 years, many organizations will experience significant shortages of skilled workers. At the same time, because of longer lifespans and a gradual rise in what society has considered the traditional retirement age of 65, older workers will represent a growing proportion of the American workforce. For a variety of reasons, many of these older workers desire to continue working and, if retained and engaged, they constitute a significant labor source for mitigating the emerging shortages of skilled workers. However, many organizations are not prepared to take advantage of this demographic shift; some even generate barriers that impede the retention and engagement of older workers. In this article, we identify a variety of ways in which organizations can retain and engage older workers to meet their staffing needs and enhance organizational performance. We also discuss the relationship of these proposals to prominent theories of motivation in management.     

The capital structure implications of pursuing a strategy of innovation

In this paper, we argue that consideration of firm strategy can help illuminate the choices managers make between debt and equity financing. Within an industry, the form of competition that each firm chooses will determine the strategic value to the firm of maintaining financial slack. Our empirical analysis yields strong support for the proposition that financial slack should be a particularly critical strategic imperative for firms pursuing a competitive strategy premised on innovation. We also demonstrate that firms pursuing such a strategy that fail to recognize the value of financial slack are likely to perform poorly. Copyright © 2003 John Wiley & Sons, Ltd.     

Lead markets, innovation differentials and growth

This article suggests that the specialization of countries in international trade is determined by the lead-lag market pattern of national markets. Many internationally successful innovations have been adopted first in one country while other countries initially either preferred other designs or an established product. A model for the international diffusion of innovations is presented in which nationally preferred innovation designs compete to become a globally dominant design. In this model, there are country-specific market attributes that increase the likelihood that the choice a country makes among alternative technologies is followed around the world. It is argued that technological knowledge gaps are not the origin of an international competitive advantage. Instead, a country gains a competitive advantage because a specific innovation design was adopted earlier than in any other country. This gives local firms a head start in producing, gathering marketing intelligence and securing the property rights of a globally successful innovation. In countries with lag market characteristics, domestic innovations are less likely to get adopted worldwide. Lag markets often switch from a domestic innovation design to a foreign innovation design, which increases imports. The lead-lag market explanation of trade specialization has implications for national policies. In this model domestic innovations do not always foster exports; idiosyncratic innovations induced by lag market contexts can hamper the export chances of local firms and in the end lead to an increase in imports. It is suggested that in order to increase exports, national policies have to distinguish between a domestic lead and lag market context in each industry. While in a lead market context, traditional policy instruments that enhance the rate of innovations are effective, in a lag market situation national follower strategies are more appropriate.     

基础力学课程教学改革的研究与实践

该文在深入分析基础力学各相关课程相互关系的基础上，认为基础力学课程的改革，应该优化组合备相关课程内容，减少重复内容，形成新的教学体系；应该在教学手段上注意现代化教学手段与传统教学手段的结合，激发学生的学习兴趣，提高课堂的效率；也强调实验环节的重要性，要注重学生动手能力的培养。     

我国国债的风险评估与防范

从国债的可持续性、国债的货币扩张效应、国债对经济增长的影响三个层面评估了我国当前的国债风险，并针对我国的国债特点，提出了防范国债风险的措施。     

高校政治思想工作的创新思考

新时期高校思想政治工作要与教育教学相统一，要做到人性化，强化人本意识，坚持以学生为本，增强历史责任感和使命感，切实把大学生思想政治教育工作提高到一个新的水平。     

国家行为与产权：一个新制度经济学的分析框架

早期的产权理论侧重于微观层次的分析，较少考虑中观（利益集团）及宏观层次（国家）对产权结构形成的影响及不同层次产权的交互作用的机制。文章从新制度经济学关于国家的定义入手，通过对个体权力与国家、集体行动与国家以及法治化社会与国家的三个层次的分析，提出建立产权制度分析的国家模型，从而论证国家与产权制度变迁的关系。     

我国液体生物质燃料开发问题与制度方法创新

当前,液体生物质燃料开发已经成为一个世界性实践问题.本文结合我国及云南实际,分析液体生物质燃料开发进程中的问题及其成因,进而从制度与方法方面提出我国液体生物质燃料开发的思路.     

A conceptual framework of anonymity in Group Support Systems

As the development and use of automated systems for collaborative work grows, the need for a better understanding of these systems becomes more important. Our focus is on one type of system, a Group Support System (GSS) and, in particular, on one important aspect of a GSS—anonymity. A conceptual framework for the study of anonymity in a GSS is presented, which describes the general classes of variables and their relationships. These variables include the factors that influence anonymity in a GSS, types of anonymity, and the effects of anonymity on a message sender, receiver, group process, and outcome. Each of these variables is discussed with working propositions presented for important group process and outcome measures. The objectives of this article are to highlight the importance and complexity of anonymity, to act as a guide for empirical investigations of anonymity, and to influence future GSS development and use.