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For the past 200 years, humans have benefited from the abundant, inexpensive, and easily obtained energy of fossil fuels. Energy surpluses such as this are unusual in human history. In systems with little surplus energy, population growth is low and complexity emerges slowly due to the energetic costs it carries. On the rare occasions when energy is readily available, societies respond by growing rapidly. They must become more complex in response to the social, economic, and resource challenges of dense population. More complex societies are more expensive, requiring greater energy per capita. The process of increasing complexity necessitates greater energy production, creating a positive feedback cycle. Past societies have collapsed under such pressures. Population and complexity grew rapidly when the Industrial Revolution replaced economies based on annual solar radiation with economies fueled by fossil energy. The Green Revolution of the 20th century is credited with preventing mass starvation, but it has made food production and sustaining population ever‐more dependent on high‐energy (low‐entropy) inputs. Some believe innovation will overcome the limitations of resources and permit unchecked growth. However, increases in complexity, innovation, and fossil energy are all subject to diminishing returns, and cannot continue to support population at current levels.  相似文献   

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A transversal generated by a system of distinct representatives (SDR) for a collection of sets consists of an element from each set (its representative) such that the representative uniquely identifies the set it belongs to. Theorem 1 gives a necessary and sufficient condition that an arbitrary collection, finite or infinite, of sets, finite or infinite, have an SDR. The proof is direct, short. A Corollary to Theorem 1 shows explicitly the application to matching problems. In the context of designing decentralized economic mechanisms, it turned out to be important to know when one can construct an SDR for a collection of sets that cover the parameter space characterizing a finite number of economic agents. The condition of Theorem 1 is readily verifiable in that economic context. Theorems 2–5 give different characterizations of situations in which the collection of sets is a partition. This is of interest because partitions have special properties of informational efficiency.  相似文献   

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青岛市官产学研合作现状及对策   总被引:1,自引:0,他引:1  
文章在分析青岛市目前官产学研合作的现状的基础上,提出提高青岛市产学研合作的对策建议,充分利用这一机遇,为青岛市的发展带来新的力量,加快创新型城市的建设步伐。  相似文献   

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Workfare programs are state-instituted programs that require able-bodied persons with children of school age who wish to claim welfare payments to participate in job training programs, and, eventually, to enter the work force. The philosophy of workfare is based on the value of work and the goal of self-determination. However, as a mandatory program for welfare recipients, workfare requires of those recipients certain duties which, according to those who challenge workfare, interfere with the freedom to choose what one will do with one's life. Whether some form of workfare will be adopted as part of our national welfare system remains to be seen. What the debate about such a program suggests is that welfare, in itself, by ignoring the necessity of security and education for full human agency, neither satisfies basic needs nor prepares its recipients for any life other than that of dependency. With all its difficulties workfare nevertheless presents an alternative to welfare that, at least in theory, more closely identifies its purpose with the values of our society.  相似文献   

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The escalating rate of obesity in the US highlights the importance of understanding the causes for this rise. In this paper I employ the First, Second, and Third National Health and Nutrition Examination Surveys to estimate a structural model of the determinants of adult obesity. To control for the potential endogeneity of some explanatory variables, such as caloric intake (adjusted for activity level) and smoking, a set of reduced form equations for these outcomes is estimated simultaneously with the obesity equation. To identify each equation, I use an array of state-level characteristics as instrumental variables. Trends in these variables shed light on the sources of the rapid increase in obesity since 1980.  相似文献   

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The current theory proposes that responses to dissatisfaction differ in constructiveness versus destructiveness and activity versus passivity, defining four categories of response: exit, voice, loyalty, and neglect. The manner in which employees react to job dissatisfaction is determined by three variables: overall job satisfaction; quality of job alternatives, and magnitude of investments in the job. This article presents a meta-analysis of the results of five studies in a program of research designed to test the current theory. Ten of 12 theory predictions received good support: Greater job satisfaction was associated with greater tendencies toward voice and loyalty, and with lesser exit and neglect. Superior alternatives were associated with greater tendencies toward exit and voice, and with lesser neglect. Greater investment size was associated with greater tendencies toward voice and loyalty, and with lesser neglect.  相似文献   

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In this paper we argue that the impact of external scale economies and diseconomies on city size is not nearly as clear-cut as it is tacitly believed in urban economics. Similarly, city-size distortions are not caused by externalities alone. Indivisibility and nonreplicability, which prevent establishing the “right” number of cities, may represent a source for city-size distortions which can be stronger than the standard resource misallocation resulting from external scale economies and diseconomies. It follows that a direct population dispersion policy is not just an inferior substitute to Pigouvian taxes and subsidies but rather a useful complement.  相似文献   

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We construct a dynamic model of corruption in organizations where officials privately know their propensity for corruption and clients optimally choose the bribe offered. We show that there is a continuum set of stationary bribe equilibria due exclusively to the dynamic nature of the model and the endogenous determination of bribes. This can explain why similar countries have stable but different "implicit prices" for the same illegal services. We also show that, by not considering the reaction of clients, traditional analysis have systematically overestimated the beneficial effect of increasing wages as an anticorruption measure.  相似文献   

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Congestion costs in urban areas are significant and clearly represent a negative externality. Nonetheless, economists also recognize the production advantages of urban density in the form of positive agglomeration externalities. The long-run equilibrium outcomes in economies with multiple correlated but offsetting externalities have yet to be fully explored in the literature. Therefore, I develop a spatial equilibrium model of urban structure that includes both congestion costs and agglomeration externalities. I then estimate the structural parameters of the model using a computational algorithm to match the spatial distribution of employment, population, land use, land rents, and commute times in the data. Policy simulations based on the estimates suggest that congestion pricing may have ambiguous consequences for economic welfare.  相似文献   

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This paper analyzes the properties of subsampling, hybrid subsampling, and size-correction methods in two non-regular models. The latter two procedures are introduced in Andrews and Guggenberger (2009a). The models are non-regular in the sense that the test statistics of interest exhibit a discontinuity in their limit distribution as a function of a parameter in the model. The first model is a linear instrumental variables (IV) model with possibly weak IVs estimated using two-stage least squares (2SLS). In this case, the discontinuity occurs when the concentration parameter is zero. The second model is a linear regression model in which the parameter of interest may be near a boundary. In this case, the discontinuity occurs when the parameter is on the boundary.  相似文献   

16.
Oligopoly, Financial Structure, and Resolution of Uncertainty   总被引:3,自引:0,他引:3  
We characterize equilibria of a multistage game in which competing duopolists may acquire and share information in advance of choosing their financial structure which, in turn, precedes production. Given sufficient uncertainty, equilibria exist in which the efficiency and, possibly, coordination gains to acquiring and sharing perfect information are sufficient to break Brander and Lewis's (1986) result wherein both firms issue debt to their mutual disadvantage. However, more interesting may be the robustness of that result when uncertainty is low or when information is imperfect. The key insight is that the consequences of issuing debt are invariant to the level of uncertainty, given that firms can recalibrate the terms of debt to achieve the Stackelberg solution.  相似文献   

17.
贾冀丰 《价值工程》2014,(27):21-23
基于某公司高中低负效加油站的经济效益、劳动效率、人工成本的投入产出能力的分析,通过对标管理对高中低负效站进行评价,查找差距,以寻求低负效站转变途径。  相似文献   

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中共中央十五届五中全会强调指出:制定"十五"计划并顺利实现"十五"目标,必须把发展作为主题,把结构调整作为主线,把改革开放和技术进步作为动力,把提高人民群众生活水平作为根本出发点.在这一战略规划中,"以改革开放和科技进步作为动力"是需要我们特别关注的问题.这一问题的核心可以理解为三大创新,即观念创新、体制创新和科技创新.如果没有实现这三个创新的基础环境与条件,进而这三个创新就无法实现,或实现的程度不够,那么,实现"十五"计划的目标亦就失去了动力源泉.因此,怎样认识创新以及创造实现观念创新、体制创新和科技创新的基础环境与条件,就成了问题的关键.  相似文献   

19.
We construct a dynamic model of corruption in organizations where officials privately know their propensity for corruption and clients optimally choose the bribe offered. We show that there is a continuum set of stationary bribe equilibria due exclusively to the dynamic nature of the model and the endogenous determination of bribes. This can explain why similar countries have stable but different "implicit prices" for the same illegal services. We also show that, by not considering the reaction of clients, traditional analysis have systematically overestimated the beneficial effect of increasing wages as an anticorruption measure.  相似文献   

20.
This paper studies a competitive dynamic model with firm level uncertainty and derives implications for the distribution of firm values and Tobin's q. Allowing for entry and exit, the model determines endogenously the degree of selection. A consequence of this selection is that average industry q values are biased above one. As parameters describing the technology and firm level uncertainty are changed, the equilibrium distribution for q values changes. This comparative statics is developed in the paper.  相似文献   

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