In this paper an intervening opportunities model with spatial dominance is developed. The usual assumption in spatial theory
is that decision makers are influenced not just by the size of a destination or distance but by these two factors in combination, that is, spatial dominance. Decision-makers will have more knowledge about, and clearly perceive destinations that exert
the greatest amount of spatial dominance on their origins, just as they would primate cities. Thus destinations are ranked
in terms of the spatial dominance calculated for each destination. Empirical verification of the model utilizes state-to-state
migration flow data for the US. Calibration results compare favourably with the traditional intervening opportunities model
and the production constrained gravity model.
Received: 7 October 1999/Accepted: 15 June 2000 相似文献
In the Mediterranean Sea, socio-economic drivers may accelerate the process of exclusive economic zone (EEZ) declarations. Despite the challenges, the EEZ declarations may provide important opportunities for leveraging change to national policy towards the development of large-scale conservation of marine ecosystems and biodiversity in this zone. Using the Mediterranean Sea as a case study, we aim to highlight a set of best practices that will maximize the potential for the development of large-scale marine conservation initiatives. These include a range of approaches, such as using surrogates to fill the many biodiversity data gaps in the region, further the development of consistent and open access databases, and the utilization of technological developments to improve monitoring, research and surveillance of less accessible and under-explored marine areas. The integration of Mediterranean-wide and local conservation efforts, the facilitation of transboundary collaboration, and the establishment of regional funds for conservation will further enhance opportunities for marine conservation in this region. 相似文献
Research on access to healthy foods often emphasizes the spatial proximity of residents to food stores like supermarkets as a way to gauge overall accessibility. Much of the literature has focused on locating the closest facility, assuming that access to one food store is sufficient. Given evidence that access to multiple healthy food stores can improve diets, however, this article examines how closest facility measures differ from cumulative opportunity accessibility measures across space in a medium-sized U.S. city. Differences in access between automobile and transit riders, using realistic travel time costs, are also considered. Results demonstrate that the two types of accessibility measures produce different accessibility geographies and that there are disparities in access for those dependent on transit. These findings indicate that researchers should carefully consider whether access to one supermarket opportunity is enough and pay special attention to the mode residents rely on to access food. 相似文献
Understanding the institutional dimensions of climate change adaptation (CCA) is critical to the adaptation process. The institutional changes that follow the introduction of a CCA measure affect certain areas of governance, including social, political, policy, and other domains that are already exposed to prevailing institutions. Thus, understanding CCA necessitates analysis of the interplays between and among institutions that exist within a hierarchical structure, as well as the examination of how institutions across different scales define the challenges in CCA implementation. This article contributes to this discussion by investigating the challenges in mainstreaming CCA into local land use planning in Albay, Philippines. It applies a four-stage mixed methodology and uses a modified Institutional Analysis and Development framework as its primary analytical guide. Its findings imply that: (1) mainstreaming CCA is a multi-scale, multi-setting endeavour; (2) mainstreaming CCA operationalization involves networks of interacting institutions and institutional arrangements; and (3) addressing the challenges in mainstreaming needs extensive institutional transformations that reach across the various institutional settings within these networks.
POLICY RELEVANCE
This article advocates that, in designing strategies to address the challenges in mainstreaming CCA, analysts, planners, and policy makers must understand that the challenges exist within a network of institutional settings, and that these challenges encompass a chain of institutional interactions or interplays within this network. Accordingly, overcoming these challenges necessitates broad institutional reforms that go beyond the institutional setting where CCA is to be mainstreamed. Moreover, this article suggests that CCA policy making and analysis must focus on the vertical, horizontal, and network linkages and relationships created by institutional arrangements, as well as on the interplays facilitated by these arrangements. More importantly, there is a need to determine whether the institutional interplays between and among existing and planned institutions are complementary, counterproductive, conflicting, overlapping, neutral, or coexisting. Such knowledge will assist policy makers and analysts to understand the existing and potential barriers to, as well as identify opportunities for, adaptation. Consequently, the solutions to address the barriers, and the strategies that can take advantage of the opportunities, can be formulated effectively. 相似文献