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71.
This study explores the growth of electronic home shopping in terms of likely transportation and communication interactions. Although opportunities exist to shop from home today, most consumers initiate travel trips to stores or markets. Widespread use of automobiles has facilitated the retailing configurations we know today but the development of new electronic networks could change this. This study establishes a baseline to explore shopping activities using two‐day travel activity data from a large U.S. metropolitan area. It is found that people who telework from home today spend more time engaged in shopping activities than other workers. Potentially, their saved work travel is converted into new trips. In the future, saved shopping travel might be converted into other types of travel, and modelling results show that for busy working women, there is a latent demand for maintenance‐related activities. The study results suggest that electronic home shopping will bring into play complex interactions between communications and transportation. 相似文献
72.
Thomas Street 《Coastal management》2013,41(4):467-480
Domestic management of historic shipwrecks and other Underwater Cultural Heritage (UCH) resources located in the United States coastal zone is extensively fragmented and a portion of it has significant implications in terms of international law. In the United States coastal zone, UCH (largely historic shipwrecks) falls under one of three general regimes, depending on where the resource is located and subject to specific and individual requirements: the General Maritime Law, the Abandoned Shipwreck Act, and the Marine Protection, Research and Sanctuaries Act, also known as the Marine Sanctuaries Act. After examining the development of and current status of these regimes, this article will suggest policies for a stronger, more coordinated federal management regime in United States coastal waters. It will specifically argue that a recent decision by the United States Court of Appeals for the Fourth Circuit provides a well-designed paradigm that could be linked with pertinent aspects of the three identified regimes to create a unified coastal governance mechanism for sunken historic shipwrecks. 相似文献
73.
The Ohio Department of Natural Resources and the U.S. Office of Coastal Zone Management have proposed the Old Woman Creek estuary on Lake Erie as the nation's first freshwater estuarine sanctuary. Designation as an estuarine sanctuary will preserve 637 acres of marshland, sand bar, a barrier beach, and surrounding forested uplands for public education and research. The original January 1975 grant application required modification following local residents’ objections to purchases of highly productive farmland and land‐use controls on a watershed‐wide buffer zone. A federal grant award was made in July 1977, with full acquisition anticipated by the end of 1978. 相似文献
74.
Yves Dandonneau Christophe Menkes Olaf Duteil Thomas Gorgues 《Journal of Marine Systems》2008,69(3-4):226
Some organisms that live just below the sea surface (the neuston) are known more as a matter of curiosity than as critical players in biogeochemical cycles. The hypothesis of this work is that their existence implies that they receive some food from an upward flux of organic matter. The behaviour of these organisms and of the associated organic matter, hereafter mentioned as floating biogenic material (FBM) is explored using a global physical–biogeochemical coupled model, in which its generation is fixed to 1% of primary production, and decay rate is of the order of 1 month. The model shows that the distribution of FBM should depart rapidly from that of primary production, and be more sensitive to circulation patterns than to the distribution of primary production. It is trapped in convergence areas, where it reaches concentrations larger by a factor 10 than in divergences, thus enhancing and inverting the contrast between high and low primary productivity areas. Attention is called on the need to better understand the biogeochemical processes in the first meter of the ocean, as they may impact the distribution of food for fishes, as well as the conditions for air–sea exchange and for the interpretation of sea color. 相似文献
75.
Jon Grant Cedric Bacher Peter J. Cranford Thomas Guyondet Michel Carreau 《Journal of Marine Systems》2008,73(1-2):155-168
A fully-coupled biological–physical–chemical model of a coastal ecosystem was constructed to examine the impact of suspended mussel culture on phytoplankton biomass in Tracadie Bay, Prince Edward Island, Canada. Due to the extent of mussel culture there, we hypothesised that shellfish filtration would control the concentration and distribution of phytoplankton and other suspended particles in the bay. Circulation was delineated with a tidally-driven 2D numerical model and used to drive an ecosystem model with a focus on pelagic components including phytoplankton production, nutrients, detritus, and mussels. The benthos were treated as a sink. Nutrients and seston were forced by tidal exchange and river input, with phytoplankton additionally forced by light. Boundary conditions of seston and nutrients were derived from field studies with an emphasis on the contrast between spring (high river nutrients, low temperature) and summer (low river inputs and high temperatures). Model output was used to map phytoplankton carbon over the bay for each season and in the presence of mussels and river nutrient input. Results indicate severe depletion effects of mussel culture on overall phytoplankton biomass, but no spatial pattern that can be attributed to grazing alone. Primary production generated by nutrient-rich river water created a mid-bay spike in phytoplankton that dominated the spatial pattern of chlorophyll-based carbon. Model results were validated with surveys from a towed sensor array (Acrobat) that confirmed the river influence and indicated bay-wide depletion of 29% between high and low water. Our model results indicate that the farm-scale depletion emphasised in previous studies cannot simply be extrapolated to seston limitation at the ecosystem level. 相似文献
76.
Participation by local governmental officials is not given the same attention in the literature as that of citizens, publics, technical experts, or stakeholders. Yet, local governments are often a keystone to successfully implementing and enforcing coastal management policies. Qualitative analysis of open-ended interviews with local government officials from three national estuary program applications in New England revealed factors related to nine themes that shaped decisions to participate or not. Three categories of factors help to clarify the different types of influence agencies have over local government officials' decisions about whether or not to participate: factors associated with the character of individuals, with the context, and with the process. This taxonomy helps to clarify the kinds of opportunities available to project leadership to influence local government officials toward participating in regional coastal management processes. An important finding is that project staff should listen and learn about the concerns of local government officials and then create a process that accommodates and overcomes barriers to their participation. 相似文献
77.
Lisa-Ann Gershwin Monica De Nardi Kenneth D. Winkel Peter J. Fenner 《Coastal management》2013,41(1):22-41
Dangerous marine stingers (jellyfish) are an emotive issue in tropical Australia, where they are widely regarded as the number one marine health threat. However, numerous severe and fatal stings have been reported throughout the tropical and temperate seas of the world, indicating that marine stingers are a global health problem. Further, life-threatening jellyfish stings are more frequently reported globally now compared to earlier decades, possibly as a result of improved recognition and reporting, or increased spatial and/or temporal distribution or densities. As stinging incidents may also have significant financial implications (lost tourism revenues and liability settlements), and the treatment of envenomed patients comes at high cost to the taxpayer, this issue is also a management challenge. This article outlines suggested approaches, based largely on Australian experience, for dealing with this under-recognized global coastal management issue. 相似文献
78.
This paper analyzes trip chaining, focusing on how households organize non-work travel. A trip chaining typology is developed using household survey data from Portland, Oregon. Households are organized according to demographic structure, allowing analysis of trip chaining differences among household types. A logit model of the propensity to link non-work trips to the work commute is estimated. A more general model of household allocation of non-work travel among three alternative chain types — work commutes, multi-stop non-work journeys, and unlinked trips — is also developed and estimated. Empirical results indicate that the likelihood of linking work and non-work travel, and the more general organization of non-work travel, varies with respect to household structure and other factors which previous studies have found to be important. The effects of two congestion indicators on trip chaining were mixed: workers who commuted in peak periods were found to have lower propensity to form work/non-work chains, while a more general congestion indicator had no effect on the allocation of non-work trips among alternative chains. 相似文献
79.
Kirk Johnson Kenneth Button 《Transportation Research Part D: Transport and Environment》1997,2(4):223-231
Benefit cost analysis in a variety of guises has established itself as a useful tool in public policy-making. It is an approach widely adopted in appraising a wide range of infrastructure investments and has been regularly used in legal proceedings. In the context of this study, it forms a common procedure for assisting in the assessment of the social benefits and costs of airport investment. It is not, however, a technique without its limitations. Beside a range of technical concerns, conducting a comprehensive benefit cost analysis can be resource-intensive and time-consuming. Recently, there have been efforts to make its application more efficient by adopting benefit transfer procedures. This involves making use of findings from one study as inputs into other policy-making activities. While applying secondary data to a new policy issue has a long pedigree, new areas of application involve taking non-market valuations of externalities from one study and transferring them to a different policy site. This paper looks at some of the limitations of employing benefit transfers and uses noise nuisance aspect of airport investment policy appraisal as an illustrative case. Based upon a meta-regression assessment of hedonic price models, the findings suggest that caution should be exercised in conduction benefit transfers. 相似文献
80.
Short-line railroad managers discuss their industry 总被引:1,自引:0,他引:1
Johnson James C. McClure Diane J. Schneider Kenneth C. Wood Donald F. 《Transportation》2004,31(1):97-123
In the United States, the 1980 Staggers Rail Act created a positive regulatory environment for the creation of new short-line railroads. At present there are about 450 of these railroads that have less than 250 miles of trackage. This study asked managers/owners of these railroads two basic questions. First, what do you believe is the single most important trend that is currently taking place in your industry. The most frequently noted trend was the frustration of working with the larger Class 1 railroads. Five additional trends were also identified by the respondents. The second question asked the respondents if they thought the short-line sector of the rail industry will become more or less important in the next ten years and why. About 70% of the owner/managers believed their industry would become more important in the next decade. The most commonly expressed reason for this position is that the Class 1 railroads will increasingly specialize in mainline service only. Three other rationales were also enumerated. For the managers that thought their industry would become less important, the most noted reason was their trackage would not safely transport the newer very heavy bulk commodity freight cars. 相似文献