共查询到15条相似文献,搜索用时 15 毫秒
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ABSTRACT. In this paper we compare two regulation instruments, flat‐rate and increasing block‐rate pricing. The analysis applies to a competitive industry with free entry. Charge for irrigation water is a concrete example. It is shown that flat‐rate pricing leads to a first‐best social optimum, while with block‐rate pricing where the highest block set at the marginal cost, there is over production, firms are too small, and loss of economic surplus occurs. Moreover, first‐best is not implementable by increasing block‐rate pricing. This is in contrast to the commonly accepted view that block‐rate pricing is superior to flat‐rate pricing by allowing for income redistribution while preserving efficiency. Several second‐best situations are analyzed to show: 1) Block‐rate pricing with the highest block at the social marginal cost is optimal when the regulator must preserve the number of firms. 2) Water pricing alone cannot implement social optimum subject to a constant level of agricultural production. 3) Lobbying and political pressures, which force the regulator to sustain a constant average water price, result in optimal block‐rate pricing with the highest block below the social marginal cost. 相似文献
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ABSTRACT. We model the value of environmental research in the presence of uncertainty about thesources of environmental pollutants and natural processes affecting the level of pollution. The model may be used to estimate the value of environmental research directed at resolving the uncertainty. We illustrate the model using a numerical simulation of a hypothetical case involving nutrient pollution of coastal waters. We show that the ex ante value of research is positively related to the level of uncertainty. There is a diminishing return with respect to the level of research investment. We find that research is more valuable ex post if it leads to unexpected findings. 相似文献
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本文研究了值分布的一个分支-幅角分布论中的Julia方向存在性定理.利用A. Eremenko得到的Picard型定理建立了复投影空间上的全纯曲线与代数超曲面相联系的Julia方向存在性定理;并给出一例子作为对定理的补充. 相似文献
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ABSTRACT. Many anadromous salmonid stocks in the Pacific Northwest are at their lowest recorded levels, which has raised questions regarding their long‐term persistence under current conditions. There are a number of factors, such as freshwater spawning and rearing habitat, that could potentially influence their numbers. Therefore, we used the latest advances in information‐theoretic methods in a two‐stage modeling process to investigate relationships between landscape‐level habitat attributes and maximum recruitment of 25 index stocks of chinook salmon (Onocorhynchus tshawy‐tscha) in the Columbia River basin. Our first‐stage model selection results indicated that the Ricker‐type, stock recruitment model with a constant Ricker a, i.e., recruits‐per‐spawner at low numbers of fish) across stocks was the only plausible one given these data, which contrasted with previous unpublished findings. Our second‐stage results revealed that maximum recruitment of chinook salmon had a strongly negative relationship with percentage of surrounding subwatersheds categorized as predominantly containing U.S. Forest Service and private moderate‐high impact managed forest. That is, our model predicted that average maximum recruitment of chinook salmon would decrease by at least 247 fish for every increase of 33% in surrounding subwatersheds categorized as predominantly containing U.S. Forest Service and privately managed forest. Conversely, mean annual air temperature had a positive relationship with salmon maximum recruitment, with an average increase of at least 179 fish for every increase in 2°C mean annual air temperature. 相似文献
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This article proves the existence of singular directions of value distribution theory for some transcendental holomorphic curves in the n-dimensional complex projective space Pn(C). An example is given to complement these results. 相似文献
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对于随机时间序列模型Xt=φtXt-1 ε,由于当{φ}在不同的情况下.具有不同的平稳性质.本文利用特征函数和矩的关系讨论了模型Xt=φXt-1 εt,在序列{φt)为正态MA(2)条件时有平稳解的充分必要条件,并利用递归方法给出了较详细的证明. 相似文献
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《数学物理学报(B辑英文版)》2015,(5)
In this article, we study the flows of curves in the Galilean 3-space and its equiform geometry without any constraints. We find that the Frenet equations and the intrinsic quantities of the inelastic flows of curves are independent of time. We show that the motion of curves in the Galilean 3-space and its equiform geometry are described by the inviscid and viscous Burgers' equations. 相似文献
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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). 相似文献
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ABSTRACT. We combine new concepts of noncooperative coalition theory with an integrated assessment model on climate change to analyze the impact of different protocol designs on the success of coalition formation. We analyze the role of “single versus multiple coalitions,”“open versus exclusive membership,”“no, weak and strong consensus about membership” and “no transfers versus transfers.” First, we want to find out whether and how modifications of the standard assumptions affect results that are associated with the widely applied cartel formation game in the noncooperative game theoretic analysis of international environmental agreements. Second, we discuss normative policy conclusions that emerge from the various modifications. Third, we confront our results with evidence on past international environmental treaties and derive an agenda for future research. 相似文献
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<正> In the present paper we propose to establish certain theoremsconcerning plane sections of the circumscribed developable of a curvein the projective n-dimensional space s_n((?)3).The planes in considera-tion are supposed to be in the osculating spaces s_3 of the curve.Forthe planes of other kinds the corresponding sections must have a singularpoint of higher order and consequently require more complicated repre-sentation,as we have shown in other places.The allied problemwill be considered in a subsequent paper. 相似文献
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对连通有限型谱X,Y,存在着Adams谱序列(ASS){Ers,t,dr}满足(1)drErs,t→Ers+r,t+r-1是谱序列的微分,(2)E2s,t≌ExtAs,t(H*(X),H*(Y)),(3)并且收敛到[∑t-sY,X]p.当X是球谱S,Moore谱M,Toda-Smith谱V(1)时,(πt-sX)p分别为S,M,V(1)的稳定同伦群.本文通过Adams谱序列,发现了球谱S的稳定同伦群中的一族非零元素~γth0b02及Toda-Smith谱V(1)的稳定同伦群中的非零元素h0b12.在利用Adams谱序列求解同伦群的过程中,需要计算有关ExtAs,t(H*X,H*Y)的结果.利用谱的上纤维序列导出的Ext群的正合序列和May谱序列,得出ExtAs,t(H*X,H*Y)的某些结果.本文令p≥7为奇素数,q=2(p-1). 相似文献
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<正> 本文是[1]、[2]的续篇,一切符号及定义均沿袭[1]、[2]. §1.q过程的存在性 由[1]定义4.1知,可微马氏过程之转移密度函数是q函数.[1]文主要研究的问题是:在何种条件下,马氏过程是可微的,即有转移密度函数.而本文研究的,恰是[1]之 相似文献
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设P≥7素数,A为模P的Steenrod代数.我们利用Adams谱序列证明了球面稳定同伦群π*S中,存在由所表示的新的非平凡元素族,其中q=2(p-1),3≤s
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