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11.
Farmers in the Sahel have been acknowledged for reclaiming degraded lands and improving food security by ingeniously modifying traditional agroforestry, water, and soil management practices. Despite the advantages offered by this range of farming techniques, their adoption rate is influenced by several factors. Using multivariate probit models and a correlation coefficient, this article examines the factors influencing the adoption of five land management practices based on 220 household and 40 farm surveys in four adjacent rural communities in southern Burkina Faso. The model results indicate that household labor force, education of household head, land tenure security, livestock holding, and membership in farmers’ groups influence the adoption of zaï practice, composting, improved fallow, stone bunds, and live hedges. However, two of the surveyed factors ‐ number of farms and visit by agricultural extension staff during the 12 months prior to the survey ‐ were not significant. Furthermore, a significant correlation was found between different land management practices, e.g., the decision to practice zaï is significantly linked to that of live hedges and composting. Zaï practice and stone bunds are considered labor intensive, which explains their significant correlations with household labor force at the 1% and 5% levels of significance, respectively.  相似文献   
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Packery Channel is part of a complex of storm washover channels which, before 1912, have opened intermittently, linking the Laguna Madre and Corpus Christi Bay, Texas with the Gulf of Mexico. On 21 July 2005, with the assistance of Hurricane Emily, Packery Channel was prematurely opened to the Gulf of Mexico, months before construction of a dredged channel was scheduled to be completed. A before-versus-after, control-versus-impact (BACI) design was used to assess the effects of reopening Packery Channel on water quality and estuarine macrofauna in Mollie Beattie Coastal Habitat Community (MBCHC), Corpus Christi Bay. Two deep (approximately 1 m below m.s.l.) and two shallow (approximately 0.2 m below m.s.l.) stations were sampled monthly for physical and biological characteristics at both control and impact sites between November 2003 and March 2009. The opening of Packery Channel created a unique situation where salinities decreased after the channel opening by ameliorating hypersalinity in Laguna Madre rather than increasing salinities as would occur in most estuaries worldwide. Salinity also fluctuated in a diurnal pattern after the opening of Packery Channel. Apart from salinity, Packery Channel has caused little hydrographic change in MBCHC since opening in July 2005. There was little effect on the macrofaunal community composition. There was a greater difference in community composition between deep and shallow stations than between either before and after or control and impact sites. There have been no significant changes in abundance, biomass, or N1 diversity caused by the opening of Packery Channel.  相似文献   
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How adults and children come to understand, represent and behave within their spatial environment are topics of great interest to geographers, psychologists, environmental planners and laypeople. Considerable research and theory has been published on these and related topics. In this paper, we will review some of what is known and theorized about spatial cognition and then consider elements of our research program on the acquisition of spatial knowledge. We focus on two intimately related topics. The first is the development of a conceptual model of the knowledge structures and processes associated with acquiring, representing and accessing knowledge of a given environment. The conceptual model forms the basis for a formal computational process model intended as a simulation of actual knowledge and performance in way finding tasks. The second emphasis is an in-depth case study of the acquisition of spatial knowledge. The case study focuses on a single child acquiring knowledge of a lengthy route through an unfamiliar suburban neighborhood. It is presented as an empirical test of certain assumptions embodied within the conceptual model.Before introducing the conceptual model and the case study, we first review the state of current theory and data on spatial cognition and identify four central issues confronting researchers in this field. This review provides a necessary context for describing and evaluating our program of research. The second section of this paper discusses elements of the conceptual model and its relationship to other formal computational models. The third section considers specific hypotheses about the acquisition and representation of spatial knowledge and tests of these hypotheses from the single in-depth case study. The final discussion section of this paper is a reconsideration of the four issues raised in the first section and necessary and proposed extensions of the current research.  相似文献   
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ABSTRACT The National Environmental Policy Act of 1969, has been called a revolutionary piece of legislation. It has changed, and is still changing the traditional ways of governmental decision-making. NEPA has strongly influenced the field of water resources management. An environmental statement can now be seen not as a document to support or justify a plan, but an objective assessment of what environmental costs and benefits are involved. New York State has seized upon NEPA as an important feature of its environmental quality management programs and has used the opportunity to comment upon draft environmental statements under NEPA to increase its influences upon Federal decision-making. The Department of Environmental Conservation coordinates and synthesizes all comments and provides one unified State response on a statement. At the State level, lacking a comprehensive “little NEPA”, an extensive environmental analysis program has been built by utilizing a wide spectrum of Federal and State Laws and administrative regulations.  相似文献   
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Our jurisprudence assigns duties to persons to keep children safe. Under negligence law, a breach of duty causing an accident means the breaching party can be liable for damages inflicted on the injured person. Legislatures are considering new laws that reduce the damages that activity providers will need to pay to injured participants. Under some statutes, injured persons are precluded from maintaining lawsuits. In other cases, injured plaintiffs have a more stringent burden of proving liability. While activity providers may use insurance to pay for accident damages, for some injuries we might hold injured persons responsible. Four suggestions are offered as mechanisms to reduce tort litigation.  相似文献   
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The public is concerned that activities accompanying hydraulic fracturing in the development of shale gas resources are unnecessarily adversely affecting them and the environment and is petitioning elected representatives to take actions to reduce risks. The health risks associated with fracturing chemicals and air pollutants are relatively unknown and constitute the impetus for public concern. An evaluation of state legal and regulatory provisions regarding best management practices discloses that states are not adopting timely regulations to protect people and the environment from activities accompanying hydraulic fracturing. Simultaneously, regulatory policy concerning negative externalities suggests that governments underinvest in the protection of human health and environmental quality. Governments have choices in protecting people from dangers that accompany shale gas development. Due to the risks of injuries and unpaid damages from shale gas development, governmental policies need to evolve to accord people greater health protection.  相似文献   
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Feral swine (wild hogs) are one of the most widely distributed free-ranging mammals in the world. In the United States, feral swine serve as game animals for the sport of hunting in some areas, while they are nuisance species at other locations. Increasing feral swine populations creates negative impacts to growing crops, native plant communities, and wildlife. Feral swine can also serve as reservoirs for a number of bacterial and viral diseases that can infect wild animals, livestock, and humans. The US state governments are adopting statutes and regulations to reduce the growth and dispersal of feral swine populations. An analysis of these provisions suggests that while they seek to control feral swine populations, they are unlikely to provide any significant relief from damages to crops and native ecosystems. More localized reduction plans and a national disease control program are suggested to assuage damages being wrought by these invasive animals.  相似文献   
19.
We examine five forested landscapes in Africa (Cameroon, Madagascar, and Tanzania) and Asia (Indonesia and Laos) at different stages of landscape change. In all five areas, forest cover (outside of protected areas) continues to decrease despite local people's recognition of the importance of forest products and services. After forest conversion, agroforestry systems and fallows provide multiple functions and valued products, and retain significant biodiversity. But there are indications that such land use is transitory, with gradual simplification and loss of complex agroforests and fallows as land use becomes increasingly individualistic and profit driven. In Indonesia and Tanzania, farmers favor monocultures (rubber and oil palm, and sugarcane, respectively) for their high financial returns, with these systems replacing existing complex agroforests. In the study sites in Madagascar and Laos, investments in agroforests and new crops remain rare, despite government attempts to eradicate swidden systems and their multifunctional fallows. We discuss approaches to assessing local values related to landscape cover and associated goods and services. We highlight discrepancies between individual and collective responses in characterizing land use tendencies, and discuss the effects of accessibility on land management. We conclude that a combination of social, economic, and spatially explicit assessment methods is necessary to inform land use planning. Furthermore, any efforts to modify current trends will require clear incentives, such as through carbon finance. We speculate on the nature of such incentive schemes and the possibility of rewarding the provision of ecosystem services at a landscape scale and in a socially equitable manner.  相似文献   
20.
总结了美国斯坦福大学和橡树岭国家实验室等在美国能源部田纳西州橡树岭综合试验基地进行的铀污染原位微生物修复阶段性试验结果.本试验利用微生物以乙醇为电子供体还原地下水和沉积物中的六价铀为不溶解的四价铀,使之原位固定化.随后通过加入溶解氧和硝酸盐来试验微生物还原后的地下水层中还原固定态铀的稳定性.通过预处理和长期间隔注入乙醇...  相似文献   
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