EMPIRICAL ANALYSIS OF CLIMATE CHANGE IMPACT ON LOBLOLLY PINE PLANTATIONS IN THE SOUTHERN UNITED STATES

Abstract Few studies have empirically examined climate change impacts on managed forests in the southern United States. In this paper, we use the U.S. Forest Service's Forest Inventory and Analysis Database to fit two growth models across the South and apply the four Hadley III climate scenarios developed for the Intergovernmental Panel on Climate Change Fourth Assessment Report to project future growth and site productivity on loblolly pine plantations. The static growth model provides a direct test of whether a significant climate influence on forest growth can be statistically derived, while the dynamic growth model estimates climate effects through site productivity. Results indicate considerable spatial variation in potential future growth and productivity change on loblolly pine plantations due to climate change in the southern United States, while overall regional effects are projected to be marginal. The pattern of climate change impacts is consistent across the growth models and climate scenarios. These findings have several implications for climate change adaptation policies.     

A DELURY DEPLETION ESTIMATOR FOR WALLEYE POLLOCK (THERAGRA CHALCO‐GRAMMA) IN THE EASTERN BERING SEA

ABSTRACT. Concerns about local depletion of fish populations are intensifying, as interest becomes focused on finer spatial and temporal scales. We used the DeLury model to investigate local depletion of the eastern Bering Sea walleye pollock population by its fishery by using spatial and temporal scales thought to meet assumptions about closure and applicability. Local depletion is estimated as the slope of logarithmic catch‐per‐unit‐effort (CPUE) from the fishery versus cumulative effort, with data from 1995 1999 stratified by small areas, short seasons and years. Of 237 depletion estimators, 172 had negative slopes, 94 of which were significant, a greater number than would be expected by chance alone. Of the 65 positive slopes, 19 were significantly positive, which is also more than would be expected. Cumulative depletion over a season was inversely related to estimated initial biomass, total catch, and total effort, indicating that depletion is detected more easily in areas of low abundance and consequently lower catch and effort. Our fine‐scale estimates of depletion are much smaller than the overall depletion from annual stock assessments, showing that commercial data alone can be at best a relative index of depletion. This hyperstable relationship may result from the lack of search time in the measure of effort, fish finding technology and schooling behavior of pollock. Evidence also suggests that measures that were taken starting in 1999 to disperse the exploitation pressure in space and time may decrease local depletion, and that pollock may repopulate an exploited area in a relatively short time period (weeks).     

Is there a Trade-Off between Quality and Productivity? The Case of Diagnostic Technologies in Portugal

The purpose of this paper is twofold: first, we compute quality-adjusted measures of productivity change for the three most important diagnostic technologies (i.e., the Computerised Tomography Scan, Electrocardiogram and Echocardiogram) in the major Portuguese hospitals. We use the Malmquist–Luenberger index, which allows to measure productivity growth while controlling for the quality of the production. Second, using non-parametric tests, we analyse whether the implementation of the Prospective Payment System may have had a positive impact on the movements of productivity over time. The results show that the PPS has helped hospitals to use these tools more efficiently and to improve their effectiveness.     

区域物流的技术网络效应研究

建立了一个基于信息技术网络效应的物流信息化需求模型,来说明信息化带来的技术网络效应是物流厂商加入信息网络的动力所在.并基于1995-2010年30个省、直辖市、自治区的面板数据,运用面板单位根和面板协整方法,证明了区域物流中技术网络效应的存在.     

REGIONAL ECONOMIC IMPACTS OF CLIMATE CHANGE: A COMPUTABLE GENERAL EQUILIBRIUM ANALYSIS FOR AN ALASKA FISHERY

We compute the effects on the Alaska economy of reduced pollock harvests from rising sea surface temperature using a regional dynamic computable general equilibrium model coupled with a stochastic stock‐yield projection model for eastern Bering Sea walleye pollock. We show that the effects of decreased pollock harvest are offset to some extent by increased pollock price, and that fuel costs and the world demand for the fish, as well as the reduced supply of the fish from rising sea surface temperature, are also important factors that determine the economic and welfare effects.     

油田高含水期稳产措施配置多层目标规划

措施规划对于延长油田稳产年限 ,提高采油速度及提高最终采收率是十分必要的 .有些学者建立了油田稳产措施规划的整体或区块规划模型 ,但没有考虑实际油田生产各生产层系的地质特性和所采取措施的差别 .本文针对油田开发实际中存在多层现象 ,以区块的各个生产层为基础 ,建立了油田措施的多层目标规划模型 ,并采用合理的算法进行求解 .应用结果表明 ,多层目标规划使措施配置更精细 ,更能反映生产实际 ,是解决油田措施配置问题的一项有力工具     

MULTISPECIES AND SINGLE‐SPECIES MODELS OF FISH POPULATION DYNAMICS: COMPARING PARAMETER ESTIMATES

Abstract Population features inferred from single‐species, age‐structured models are compared to those inferred from a multispecies, age‐structured model that includes predator‐prey interactions among three commercially harvested fish species—walleye pollock, Atka mackerel, and Pacific cod—on the Aleutian Shelf, Alaska. The multispecies framework treats the single‐species models and data as a special case of the multispecies model and data. The same data from fisheries and surveys are used to estimate model parameters for both single‐species and multispecies configurations of the model. Additionally, data from stomach samples and predator rations are used to estimate the parameters of the multispecies model. One form of the feeding functional response, predator pre‐emption, was selected using AIC from seven alternative models for how the predation rate changes with the densities of prey and possibly other predators. Differences in estimated population dynamics and productivity between the multispecies and single‐species models were observed. The multispecies model estimated lower mackerel population sizes from 1964–2003 than the single‐species model, while the spawning biomass of pollock was estimated to have declined more than three times faster since 1964 by the multispecies model. The variances around the estimates of spawning biomass were smaller for mackerel and larger for pollock in the multispecies model compared to the single‐species model.     

MARINE RESERVES AS A MEASURE TO CONTROL BYCATCH PROBLEMS: THE IMPORTANCE OF MULTISPECIES INTERACTIONS

ABSTRACT. This paper explores the effects of using marine reserves as a measure to control bycatch that is of no commercial value, under different assumptions regarding the ecological interactions between targeted species and that taken as bycatch. Three cases are examined: (1) no ecological interactions between the two species, (2) targeted and bycatch species exist in a predator‐prey relationship and (3) species compete. Targeted species is assumed to consist of two sub‐populations that are discretely distributed in space, but linked through density dependent migration while bycatch species is assumed to consist of one uniformly distributed stock only. In each case the equilibrium stock levels of targeted and by‐catch species, effort and harvest are numerically calculated and compared, assuming pure open access and open access in combination with a reserve. It is of special interest to identify circumstances that allows for a win‐win situation, that is, both harvest of the targeted species and biomass of the bycatch species increase. It is shown that the ecological interactions between the two species influence the possibility of actually protecting the bycatch species through the use of a reserve, the possibility a win‐win situation, and the issue of what patch to close.     

Productivity and technical changes in the Indian pharmaceutical industry

We study the productivity change and factors driving this change in the Indian pharmaceutical industry during 1994–2003, in the backdrop of economic liberalization and change in regulatory norms. We use a non parametric Data Envelopment based-methodology to estimate productivity change and decompose it into technical and relative efficiency changes. We find that, the long-term strategic measures by a section of innovative firms that foresaw the implications from competitive forces of globalization and a change in the regulatory environment have sphereheaded the technical change. Consequently, few innovative firms, characterized by greater R&D investments, transition into higher value-added products and businesses as a step towards more technically sophisticated new drug development have pushed the production frontier, increasing the technical and productivity gains. The higher technical and R&D capabilities and wider new product portfolios of multinational companies also have contributed to the positive technical and productivity changes in the Indian pharmaceutical industry.     

INDIVIDUAL TRANSFERABLE QUOTAS AND PRODUCTION EXTERNALITIES IN A FISHERY

This paper determines the conditions under which an individual transferable quota (ITQ) system will cause fishermen to engage in cost-decreasing, rather than cost-increasing, competition. If there are production externalities (e.g., congestion or stock externalities) present, the market price of a quota will not be fully reflected in these externalities. Thus, fishermen will not fully internalize the externalities in their effort decisions. Even if there are no production externalities, an individual fisherman imposes costs on others under open access by removing a fish that was available to all fishermen. An ITQ system allows the individual who values that fish most to obtain the right to harvest the fish, so each fisherman must internalize the full social cost. Thus, an ITQ system is capable of solving the common property externality but not the production externalities in a fishery.     

Setting expediting repair policy in a multi-echelon repairable-item inventory system with limited repair capacity

Inventory systems with limited repair capacity are affected by congestion externalities, caused by use of a shared service. There is incompatibility between individual and system optimisation in considering congestion externalities. Three models are described that investigate the congestion effect in a multi-echelon inventory system which has two modes of repair, each with a limited repair capacity. An expanding repair policy employed by the bases in order to choose which repair mode to use is described and compared with different expediting policies related to congestion externalities. The expanding repair policy that considers congestion externalities was found to lead to better system performance measurement than an expanding policy with no congestion. The results of the numerical experiment indicate that the model that ignores congestion externalities—that is, the model that measures each base as an individual—leads to poorer performance measurement for every expediting repair policy, and particularly for the optimal expediting repair policy.     

不同环保意识视角下的DEA效率模型

DEA在效率分析领域具有良好的应用,随着全球气候的不断恶劣和环境的逐渐破坏,公众环保意识不断增强,在进行相关效率研究时,非期望产出越来越受到重视。以非期望产出为主要研究点,根据社会对非期望产出指标的认识规律将环保意识分为五个不同阶段,并综合考虑每个意识阶段的特征,将环境指标变动能力,环境承载能力、环境负外部性参与度、外部环境政策管理及企业生产要求纳入DEA效率分析过程中,通过对目标函数和约束条件进行不同的改进和约束,构建了不同意识阶段的DEA效率分析模型,并探讨了各阶段模型的使用范围和相互关系。最后,选取一个实例进行试算,证明各DEA模型的可行性和有效性。     

Productivity and customer satisfaction in Swedish pharmacies: A DEA network model

This paper presents a Data Envelopment Analysis (DEA) network model that allows inclusion of customer satisfaction in efficiency and productivity measures. The network consists of a production node and a consumption node and offers flexibility in modelling the production and consumption process where a firm-specific allocation of input resources to production and customer oriented activities is allowed. The proposed model is applied on a sample of Swedish pharmacies with organizational objectives that necessitates a monitoring of efficiency and productivity as well as customer satisfaction. Estimation results from the network model and a direct productivity model (without customer satisfaction) are compared and indicate that the technical efficiency is lower under the network model. The productivity results indicate productivity progress under both models, albeit with a slower rate of change under the network model.     

Effects of productivity definition and measurement on performance evaluation

Productivity has often been cited as a key factor in industrial performance, and actions to increase it are said to improve profitability and the wage earning capacity of employees. Experimental studies have shown, however, that the ultimate effects of such actions are dependent on the choice of productivity measure.Productivity has traditionally been measured in relation to a single input factor at a time, often with consequences to other factors. For example, attempts to increase the productivity of labour may eventually lead to over-investment in capital inputs and hence to high capital costs. Alternatively, observed increases in, say, value added per head, which appears to be a common measure of labour productivity, may reflect increases in material productivity rather than in the productivity of labour itself, and should, therefore, be treated with caution in any productivity-linked payment schemes.In this paper some commonly used measures of productivity, relating to both physical and financial inputs and outputs are reviewed. Adopting a modelling approach, they are compared in terms of their implications for performance evaluation and highlight their differences and similarities, strengths and weaknesses.     

Technological progress and productivity growth in the U.S. mobile telecommunications industry

The fast growing U.S. mobile wireless industry has been experiencing dramatic technological change and substantial competition. As a result of these catalysts, we argue that wireless firms have experienced significant productivity improvement and provide new evidence that technological progress almost exclusively contributed to productivity improvements in the wireless industry by significantly expanding the production possibilities set. We employ nonparametric estimation procedures based on Data Envelopment Analysis (DEA) that utilize input-output data from a representative sample of 16 firms in the mobile wireless industry to estimate productivity change, technological change, and relative efficiency change for the period spanning the years from 2000 to 2002. Our findings show that the industry experienced a significant growth of 13% in productivity, which was primarily due to an average technological progress of 9.9% in the industry. Additionally, we find that national wireless operators experienced significantly higher productivity growth and contributed more to technological progress than regional providers. Firms that were industry pioneers as evidenced by high market share at the beginning of our sample period experienced higher productivity growth and greater technological progress compared to firms with lower initial market share. Moreover, the industry experienced significantly higher productivity growth and technical progress in the later sample period between 2001 and 2002 than in the early period between 2000 and 2001.     

关于不分明凸集的几点注记

我们综合考虑作物组合和熟制、生产工艺、机群的生产效率和费用、作业适期、气候条件的随机性及其对实际田间作业天数的影响、以及相应的适时性损失,应用蒙特卡罗模拟技术,建立了一个确定各种机群结构最佳负担面积的模拟模型。并根据目前苏南地区适用的稻麦生产工艺和目前可供选用或已经过引进试验的机组性能参数,按照配套、协调和不可分割的原则,组成了七种基本机群结构。在模拟运算和灵敏度试验的基础上,对各种机群的经济规模、单位面积投资、生产费用、土地生产率和亩均纯收入等各项经济效益指标进行了详尽的分析和比较。最后,就农业机械化的发展战略、有关的政策措施以及农业的经营体制提出了我们的见解和结论。     

Centralized decision of internal transfer-prices with congestion externalities for two modes of repair with limited repair capacity

The internal transfer-prices set by an organization are what an organization's bases ‘pay’ its service centre, the depot, for its services. Since each base has a limited budget, these transfer-prices control and motivate the base's usage of two types of repair services: normal and expedited. In this paper, we implement a unique approach—transfer-prices with congestion externalities—to determine the optimal transfer-price for the expedited repair service. Inventory systems with limited repair capacity are affected by congestion externalities, which reflect the negative externalities caused by the use of a shared service. We also describe different models that develop transfer prices schemas, and which differ in the way they consider congestion externalities. Numerical illustrations based on data from an air force display the incompatibility between two optimization models. One model ignores congestion externalities, while another considers congestion externalities. In the case of congestion externalities, the base must pay extra for the expedited repair service. The increased costs are due to expanded usage of the limited repair capacity which a particular base is imposing on the rest of the system in the form of longer queues that degrade service quality.     

A COALITION APPROACH TO THE MANAGEMENT OF HIGH SEAS FISHERIES IN THE PRESENCE OF EXTERNALITIES

ABSTRACT. The current paper extends the coalition approach of the management of high seas fisheries to the presence of externalities. The coalition approach is set within the framework of a two‐stage game in which the payoffs depend on the entire coalition structure and are determined through a partition function. The relationship between the presence of externalities and the stability of the coalition structures is explored. The equilibrium coalition structures of the game are also examined. The application of the game to the Northern Atlantic bluefin tuna shows a typical picture of the high seas fisheries: the simultaneous presence of strong externalities in the coalition structures and the absence of stability of the grand coalition. A fundamental conclusion of this paper is that, generally, in order to guarantee the stability of the cooperative agreements it is not sufficient to implement a fair sharing rule for the distribution of the returns from cooperation. Stability requires a legal regime preventing the players that engage in noncooperative behavior from having access to the resource.     

Aggregation of Malmquist productivity indexes allowing for reallocation of resources

In this paper we consider aggregate Malmquist productivity index measures which allow inputs to be reallocated within the group (when in output orientation). This merges the single period aggregation results allowing input reallocation of Nesterenko and Zelenyuk (2007) with the aggregate Malmquist productivity index results of Zelenyuk (2006) to determine aggregate Malmquist productivity indexes that are justified by economic theory, consistent with previous aggregation results, and which maintain analogous decompositions to the original measures. Such measures are of direct relevance to firms or countries who have merged (making input reallocation possible), allowing them to measure potential productivity gains and how these have been realised (or not) over time.     

Existence of Equilibria in Economies with Externalities and Nonconvexities

We consider a general equilibrium model of an economy in which the production possibilities, the consumption sets and the preferences of the consumers are represented by set-valued mappings which depend on the environment to take into account the possibility of external effect. In order to encompass all kinds of nonconvexities, we do not put any convexity assumption either on the graph of the set-valued mapping which describes the technological possibilities or on the production set for a given environment. The firms are instructed to set their prices according to general pricing rules which may depend on the production plans of other producers and on consumption plans.We report an existence result of general equilibria. As in the model without external effects, the key hypotheses are bounded loss and survival assumptions. Nevertheless, we also assume that the set-valued mappings which describe the fundamentals of the economy are lower semi-continuous and have a closed graph.Our framework is sufficiently large to generalize previous works on the existence of competitive equilibria with externalities when the firms have convex production sets and on the existence of equilibria with general pricing rule without externality.