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1.
This paper considers optimal commercial policy for a trading economy which departs from neo-classical characteristics only in that a minimum-wage constraint gives rise to unemployment. Although for a flexible-wage fully employed economy the Baldwin envelope yields dominant domestic production-cum-trade possibilities, unilateral imposition of an optimum tariff is shown not necessarily to be optimal commercial policy for the minimum-wage economy. Rather, there exists an envelope, derived from foreigners' trade indifference and attained via bilateral trade policy, which dominates the Baldwin envelope when the optimum tariff is zero (as Brecher has shown it can be for a minimum-wage economy), and can still yield superior production-cum-trade possibilities when the optimum tariff is non-zero.  相似文献   
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The River Murray, Australia, is a highly regulated river from which almost 80% of mean annual flow is removed for human use, primarily irrigated agriculture. Consequent changes to the pattern and volume of river flow are reflected in floodplain hydrology and, therefore, the wetting/drying patterns of floodplain wetlands. To explore the significance of these changes, macroinvertebrate samples were compared between permanent and temporary wetlands following experimental flooding in a forested floodplain of the River Murray. Weekly samples from two permanent wetlands and four associated temporary sites were used to track changes in macroinvertebrate assemblage composition. Non‐metric multidimensional scaling was used to ordinate the macroinvertebrate data, indicating consistent differences between the biota of permanent and temporary wetlands and between the initial and later assemblages in the temporary sites. There were marked changes over time, but little sign that the permanent and temporary assemblages were becoming more alike over the 25‐week observation period. The apparent heterogeneity of these systems is of particular importance in developing river management plans which are likely to change flooding patterns. Such plans need to maintain a mosaic of wetland habitats if floodplain biodiversity is to be supported. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   
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The transboundary St Mary River drains Glacier National Park, USA, and was progressively dammed and diverted over the 20th century to support agricultural irrigation in northern Montana and southern Alberta, Canada. Following reduced instream flows, the riparian cottonwoods collapsed, and by 2000, few parental trees remained to provide seeds for cottonwood replenishment. As a novel twofold restoration strategy we: (1) worked with the dam operators to deliver a functional flow regime, a regulated instream flow pattern intended to recover some ecological function and specifically seedling recruitment, and (2) delivered cottonwood seeds by direct spreading and by sticking cuttings with seed catkins to allow gradual seed dispersal. The combination of river regulation and seeding enabled cottonwood colonization, and around 1.5% of the applied seeds produced seedlings after the first summer, at sites without livestock or heavy recreational use. Around 15% of those seedlings survived through the fourth summer, with mortality due to drought stress and flood scour, and establishment and survival were higher for the prairie cottonwood, Populus deltoides, than the narrowleaf cottonwood, Populus angustifolia. This study confirmed that the lack of seed source trees limited cottonwood colonization and demonstrated that the twofold restoration strategy provides promise for severe situations where parental trees have been lost. However, this would require substantial effort, and it would be more efficient to provide survivable instream flow patterns that avoid cottonwood collapse. Copyright © 2015 John Wiley & Sons, Ltd.  相似文献   
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With river regulation, water withdrawal is common, reducing instream flows. The opposite alteration, flow augmentation, is less common and could reveal a mechanistic coordination between flow regime, channel form, and riparian ecosystems. The Little Bow River, a naturally intermittent prairie stream in Southern Alberta, has experienced flow augmentation since the late 1890s, and the Little Bow/Highwood Project of 2004 enabled a tripling of diversion flows from 2.9 to 8.5 m3/s. We investigated the subsequent responses by assessing the channel form and riparian vegetation based on aerial photographs taken in 2000 versus 2010, and riparian birds were assessed between 2005 and 2013 to investigate associations with riparian vegetation. Following recent flow augmentation, the mean channel width increased from 12.2 to 13.5 m, while sinuosity was relatively unchanged. Streamside zones with true willows (especially Salix exigua and Salix bebbiana) increased from 7 to 11% of the river corridor, and the facultative riparian wolf willow (Elaeagnus commutata) zones increased from 16 to 20%, while grassy zones decreased from 64 to 52%. Avian species richness and Shannon–Wiener index increased, while species evenness was relatively unaltered, suggesting an increase of rarer bird species in response to the increased habitat structure and diversity following the expansion of riparian shrubs and woodland. This study revealed responses to the recent flow augmentation over the first decade of implementation, and alterations following flow augmentation would likely continue for decades until the river and riparian zones adjust to the new flow regime. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   
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Firms employ a variety of political strategies (e.g., lobbying, contributions) in an attempt to gain influence or access to the public policy process. A variety of benefits may accrue to firms that are successful in creating a linkage with the government: information, access, influence, reduced uncertainty and transaction costs, etc. However, the direct benefits of such strategies are difficult to observe. One political strategy is studied here—personal service (having a firm representative serve in a political capacity). Event‐study methodology results show that such linkages with the government positively affect firm value. These findings indicate that firm‐specific benefits may result from political strategies. Copyright © 1999 John Wiley & Sons, Ltd.  相似文献   
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Enduring rents     
Rent seeking is often studied with reference to a contemporaneous rent evaluated at a point in time. We study the social cost of rent seeking when rents endure over time, but may have to be re-contested because of imperfect rent protection, or may disappear because of deregulation. The present value of a contested rent measures the social cost of rent seeking, irrespective of imperfect rent protection and the prospect of deregulation. Rent seeking is discouraged by the inability of governments to commit to protect rents and by their inability to commit to rent-generating regulations and policies. Moreover, lasting deregulation can preempt a substantial fraction of the potential rent seeking cost.  相似文献   
8.
Most research on corporate directors has focused on two roles: agency and resource dependence. While these two roles are theoretically and practically distinct, previous research has used the same classification scheme for measuring board composition regardless of role examined. Our paper examines the resource dependence role of directors and posits that the widely used insider/outsider categorizations do not adequately capture this role of directors. A taxonomy of directors is presented specifically for studying the resource dependence role. We then apply the taxonomy to a sample of US airline firms undergoing deregulation, and examine how board composition changes parallel the changing resource dependence needs of the firms. We conclude that the board's function as a link to the external environment is an important one, and that firms respond to significant changes in their external environment by altering board composition.  相似文献   
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