Spatial ecology of common carp (Cyprinus carpio) in Lake Winnipeg and its potential for management actions

Common carp feeding and spawning behaviours negatively impact the functioning of marsh ecosystems. In the Netley-Libau Marsh, situated on the southern end of Lake Winnipeg, water level regulations, nonpoint source nutrient pollution, and the non-native common carp are thought to be the main contributors to the degradation of the marsh habitat. Using acoustic telemetry, we analysed the movement rate, frequency and timing of suspected spawning migrations, spatial ecology, and aggregation of common carp in the Lake Winnipeg drainage over a three year time period. Common carp moved the farthest during the open water period when water temperature was >5 °C. Their annual migration into Netley-Libau Marsh was correlated to ordinal date. Common carp left the marsh in late spring/early summer, presumably feeding in Lake Winnipeg, before moving to overwintering sites situated in Traverse Bay and Lake Winnipeg, where they arrived typically by October and formed aggregations. These findings will inform habitat and fisheries managers in the effort to undertake evidence-based management actions. The predictability of the movements and the tendency for common carp to aggregate indicates that exclusion techniques and commercial fishing may represent viable management solutions.     

Social distance and shopping behavior

This research was designed to see whether a reconceptualization of social distance (as measured by social class variables) between shoppers and stores would provide a basis for understanding store avoidance behavior. A survey of shoppers classified into two distinct social classes investigated their images, including social class images, of two stores that had been selected as representatives of upscale and downscale retailers. A new measure of social distance was proposed and evaluated. Controlling for other functional aspects of store image such as price and personnel, the social distance measure was found to be influential in discriminating shopping frequency groups for the two stores, providing evidence that people tend to avoid stores that are perceived as being socially distant from themselves.     

Cost Structures and Nash Play in Repeated Cournot Games

This paper reports an experiment designed to assess the effects of a rotation in the marginal cost curve on convergence in a repeated Cournot triopoly. Increasing the cost curve's slope both reduces the serially-undominated set to the Nash prediction, and increases the peakedness of earnings. We observe higher rates of Nash equilibrium play in the design with the steeper marginal cost schedule, but only when participants are also rematched after each decision. Examination of response patterns suggests that the treatment with a steeper marginal cost curve and with a re-matching of participants across periods induces the selection of Nash Consistent responses.     

Measuring market response to regulation of the cable TV industry

During the 1988–1990 period, the cable television industry was subject to a number of regulatory events. These centered on possible reregulation of rates for basic service and reduction of entry barriers for potential competitors. Using the event study methodology on a portfolio of cable firms, we find evidence that news of no reregulation caused significant positive abnormal returns. News of reregulation caused insignificant negative abnormal returns. These findings provide some support for the traditional consumer protection theory of regulation. News related to entry barriers generally had no significant effect on returns, which suggests that elements of natural monopoly may exist in the industry.     

A real options perspective on entrepreneurial entry in the face of uncertainty

In this paper we develop and test theory regarding whether entrepreneurs contemplating starting a new venture account for the value of the option to defer the entry decision. While others have illuminated the theoretical applicability of real options theory to entrepreneurship, empirical evidence in this context is lacking. Consistent with predictions derived from real options theory, we find that high uncertainty in the target industry dissuades entry, and that the irreversibility of the entry decision moderates this relationship. Furthermore, we find that the irreversibility of the investment decision can be influenced by industry‐level, firm‐level and even individual‐level factors. Copyright © 2003 John Wiley & Sons, Ltd.     

Equilibria and Pareto optima of markets with adverse selection

Summary This paper examines the efficiency properties of competitive equilibrium in an economy with adverse selection. The agents (firms and households) in this economy exchange contracts, which specify all the relevant aspects of their interaction. Markets are assumed to be complete, in the sense that all possible contracts can, in principle, be traded. Since prices are specified as part of the contract, they cannot be used as free parameters to equate supply and demand in the market for the contract. Instead, equilibrium is achieved by adjusting the probability of trade. If the contract space is sufficiently rich, it can be shown that rationing will not be observed in equilibrium. A further refinement of equilibrium is proposed, restricting agents' beliefs about contracts that are not traded in equilibrium. Incentive-efficient and constrained incentive-efficient allocations are defined to be solutions to appropriately specified mechanism design problems. Constrained incentive efficiency is an artificial construction, obtained by adding the constraint that all contracts yield the same rate of return to firms. Using this notion, analogues of the fundamental theorems of welfare economics can be proved: all refined equilibria are constrained incentive-efficient and all constrained incentive-efficient allocations satisfying some additional conditions can be decentralized as refined equilibria. A constrained incentive-efficient equilibrium is typically not incentive-efficient, however. The source of the inefficiency is the equilibrium condition that forces all firms to earn the same rate of return on each contract.Notation ={ ₁,..., _k } set of outcomes - : ₊ generic contract or lottery - A = () ; - A_o A{, where denotes the null contract or no trade - S={1,...,¦S¦} set of seller types - L(s) number of type-s sellers - M number of buyers - u: × S seller's utility function, which can be extended toA× S by puttingu(, s) ; - v. × S buyer's utility function, which can be extended toA × S by puttingv(, s) ; - f:A ₀ ×S ₊ allocation of sellers - g:A ₀ ×S ₊ allocation of buyers - A ₊ sellers' trading function - :A ×S ₊ buyers' trading function This paper has had a long gestation period, during which I have been influenced by helpful conversations with many persons, by their work, or both. Among those who deserve special mention are Martin Hellwig, Roger Myerson, Edward Prescott, Robert Townsend and Yves Younés. Earlier versions were presented to the NBER/CEME Conference on Decentralization at the University of Toronto and the NBER Conference on General Equilibrium at Brown University. I would like to thank John Geanakoplos, Walter Heller, Andreu Mas Colell, Michael Peters, Michel Poitevin, Lloyd Shapley, John Wooders, Nicholas Yannelis and an anonymous referee for their helpful comments and especially Robert Rosenthal for his careful reading of two drafts. The financial support of the National Science Foundation under Grant No. 912202 is gratefully acknowledged.     

Industrial cogeneration and regulatory policy

The 1978 Public Utility Regulatory Policy Act (PURPA) fostered decentralized generation of electricity, particularly in the form of cogeneration. A model of a firms' decision to cogenerate is developed that illustrates both the interface between the firm and an electric utility, and the firm's internal interface between its primary product and cogeneration technologies. The model is used to show that the firm may operate inefficiently in both the short run and long run owing to the fixed-proportions technology of cogeneration and PURPA mandated operating procedures, respectively. Cogenerating firms that dump heat into the atmosphere may signal inefficient behavior; therefore, monitoring heat dumping may be important in measuring the success of cogeneration.     

美国反倾销诉讼案上升的历史透视

原载:http://www.nber.org/papers/w10582一、引言反倾销条款作为美国贸易法的一个组成部分虽然已有80多年的历史,但只是在近20年间才格外引人注目。在美国的贸易政策中,反倾销在过去一直不引人注意,实际上,直到Finger,Hall和Nelso(1982)写出了开拓性的论文之后,才有这方面的经济研究。从此,对反倾销政策的研究几乎全都集中在1980年以来的这段时间里。因此,我们对1980年以前的反倾销法规的运用知之甚少,对逐渐转向更频繁地运用反倾销补救措施的程度亦知之甚少。本文旨在用历史的观点研究美国近来的反倾销,特别关注二战以来这段时间。这一…