R&D competition, absorptive capacity, and market shares

This paper deals with an oligopolistic industry where firms are engaged in cost-reducting R&D activity to maximize their market shares. The existence and uniqueness of a feedback-Nash-optimal R&D strategy for each firm are discussed. Our simulations highlight that variations in spillovers hardly influence the firms' R&D investment, if their absorptive capacities to exploit extramural knowledge depend on their R&D efforts. Moreover, extramural knowledge cannot completely replace in-house R&D. However, a high level of public R&D favors the firm with the most restrictive R&D expenditure constraint and/or with the lowest initial R&D stock, provided it invests in R&D.     

Price-raising drug enforcement and property crime: a dynamic model

Price-raising drug enforcement suppresses drug use, but it is expensive and may increase property crime. This has led to contradictory recommendations concerning how drug enforcement should or should not be used. We reconcile these recommendations by incorporating the enforcement's effects on both drug use and on property crime within an optimal-control model that recognizes whether convicted drug-involved property offenders are merely incarcerated or whether they receive some form of drug treatment.     

动态联盟与中小企业的成长

在竞争激烈、产品快速升级换代的环境下,中小企业难以完全依靠自身力量立足并取得发展,中小企业成长依赖于外部资源获取,而资源获取渠道又通常来自于各种关系交织成的复杂、交叉重叠的社会网络,文章将中小企业与动态联盟联系起来,对动态联盟这种新的企业运作模式在中小企业成长所起的作用进行论述。     

The Dynamics of Capital Structure in Transition Economies

This paper uses a dynamic unrestricted capital structure model to examine the determinants of the private companies' target financial leverage and the speed of adjustment to it in two transition economies, the Czech Republic and Bulgaria. We explicitly model the adjustment of companies' leverage to a target leverage, and this target leverage is itself explained by a set of factors. The panel data methodology combines cross-section and time-series information. The results indicate that the Bulgarian corporate credit markets were less supply -constrained than those of the Czech Republic during the period under investigation. Bulgariancompanies adjusted much faster to the target leverage than Czech firms. The speed ofadjustment related positively to the distance between target and observed ratio for Bulgarian companies while the relationship was neutral for Czech companies. The conservative policies of Czech banks and the exposure control were likely responsible for the slower adjustment among the larger companies while the opposite were true for Bulgarian banks and companies.     

How Should An Accumulative Toxic Substance be Banned?

The harmful effects on human health or ecosystems of many toxic substances depend on their cumulative concentration in the carrying medium (water, soil, or air), not just on the annual deposition rates of the substances. Accumulative toxic substances pose challenges to regulatory policy that are not faced when controlling pollutants whose damaging effects are though to depend primarily on annual emission flows. An increasingly common response is to phase out offending uses or production of the substance. In this paper we take as given the goal of phasing out an accumulative pollutant and examine different ways this could be done using a simple, partial-equilibrium dynamic model. We focus on phaseout measures in which the cumulative production and release of the offending substance over the transition period is fixed. Once this cumulative volume is reached, users must convert to a known but higher-cost substitute that is assumed to be benign. The key to the analysis is the observation that the quota on cumulative production makes production of the toxic substance during the transition analogous to extraction of an exhaustible resource with a higher-cost, nonexhaustible ‘backstop’ technology. Using this framework, we first describe the cost-effective outcome when the ‘sunset’ date is chosen to maximize product market surplus subject to the cumulative production constraint. This outcome is compared to one in which the regulator fixes the sunset date, and one in which the regulator limits annual production as well as cumulative production out of concern for acute exposure effects. Finally, we discuss the kinds of market-based policy instruments that would be appropriate for supporting a cost-effective outcome.     

Uncertainty,Learning and International Environmental Policy Coordination

In this paper we construct a simple model of global warming which captures a number of key features of the global warming problem: (i) environmental damages are related to the stock of greenhouse gases in the atmosphere; (ii) the global commons nature of the problem means that these are strategic interactions between the emissions policies of the governments of individual nation states; (iii) there is uncertainty about the extent of the future damages that will be incurred by each country from any given level of concentration of greenhouse gases but there is the possibility that at a future date better information about the true extent of environmental damages may become available; an important aspect of the problem is the extent to which damages in different countries may be correlated. In the first part of the paper we consider a simple model with two symmetric countries and show that the value of perfect information is an increasing function of the correlation between damages in the two countries in both the cooperative and non-cooperative equilibria. However, while the value of perfect information is always non-negative in the cooperative equilibrium, in the non-cooperative equilibrium there is a critical value of the correlation coefficient below which the value of perfect information will be negative. In the second part of the paper we construct an empirical model of global warming distinguishing between OECD and non-OECD countries and show that in the non-cooperative equilibrium the value of perfect information for OECD countries is negative when the correlation coefficient between environmental damages for OECD and non-OECD countries is negative. The implications of these results for international agreements are discussed.     

湖南城市竞争力的动态比较

文章首先阐述了城市竞争力动态比较的研究意义和具体途径,然后选取了适当的指标体系和分析年代,并建立了动态比较的计量数学模型,运用因子分析法对湖南省14个城市竞争力进行了动态的测算和分析。分析结果表明:湖南城市竞争力呈现出明显的非均衡发展特点;各城市在近5年内竞争力增长的趋势和幅度均有所不同;湖南城市竞争力水平与其增长能力具有显著的正相关性。     

本地市场效应、比较优势动态化与地方中枢型产业的选择

空间经济学理论表明,基于市场规模的产业本地市场效是新的比较优势的源泉。从产业本地市场效应角度考察我国区域间产业发展,利用《中国区域间投入产出表》测算中国不同区域和不同产业的本地市场效应大小,即“超常需求”的大小,发现伴随规模经济的“本地市场效应”可以较好地解释我国产业空间结构的现象。根据产业本地市场效应,即以市场需求为导向来培育主要产业是构建现代产业体系的途径之一,是未来我国产业升级的重要方向。     

静态及动态风险度量模型的实证对比分析

选取上海证券交易所金融、工业指数的收盘价为观察对象,分别对静态及动态模型、上证金融及工业指数的风险程度以及不同置信水平下的度量准确性进行了比较研究,结果表明：动态风险度量模型对VaR、ES的度量比静态模拟更加准确;上证金融指数的风险程度要略高于上证工业指数的风险程度;置信度为99%时度量风险模型要比置信度为95%时更加精确。