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631.
A new methodology for crop-growth stage-specific assessment of agricultural drought risk under a variable sowing window is proposed for the soybean crop. It encompasses three drought indices, which include Crop-Specific Drought Index (CSDI), Vegetation Condition Index (VCI), and Standardized Precipitation Evapotranspiration Index (SPEI). The unique features of crop-growth stage-specific nature and spatial and multi-scalar coverage provide a comprehensive assessment of agricultural drought risk. This study was conducted in 10 major soybean-growing districts of Madhya Pradesh state of India. These areas contribute about 60% of the total soybean production for the country. The phenophase most vulnerable to agricultural drought was identified (germination and flowering in our case) for each district across four sowing windows. The agricultural drought risk was quantified at various severity levels (moderate, severe, and very severe) for each growth stage and sowing window. Validation of the proposed new methodology also yielded results with a high correlation coefficient between percent probability of agricultural drought risk and yield risk (r?=?0.92). Assessment by proximity matrix yielded a similar statistic. Expectations for the proposed methodology are better mitigation-oriented management and improved crop contingency plans for planners and decision makers.  相似文献   
632.
Contrary to claims from American politicians, lobbyists, and oil and gas executives, allowing energy development in the Alaskan Arctic National Wildlife Refuge (ANWR) will harm the environment, compromise international law, erode the social significance of wilderness protection, and ultimately fail to␣increase the energy security of the United States. After exploring a brief history of the ANWR controversy, this piece argues that the operation of oil and gas refineries in ANWR will release discharged solids, drilling waste, and dirty diesel fuel into the ecosystem’s food-chain, as they have from oil operations in Prudhoe Bay. Less obvious but equally important, oil and gas exploration in ANWR will violate a number of international treaties on biodiversity protection. In the end, development in ANWR will threaten the concept of wilderness protection, and will do little to end US dependence on foreign sources of energy. About the Author: Benjamin K. Sovacool is a doctoral candidate in the Department of Science and Technology Studies at the Virginia Polytechnic Institute & State University in Blacksburg, Virginia. He works as a research analyst for the Consortium on Energy Restructuring and is a Senior Research Fellow for the Virginia Center for Coal and Energy Research. He also just completed a Graduate Fellowship in Energy Policy at the Oak Ridge National Laboratory in Oak Ridge, Tennessee. Readers should send their comments on this paper to: BhaskarNath@aol.com within 3 months of publication of this issue.  相似文献   
633.
This paper recommends a revision of watershed development policy in India in relation to the planning of development interventions involving agricultural intensification and rainwater harvesting following biophysical and societal impact studies carried out on two watershed development projects in Karnataka. A need for changes in policy has arisen in response to progressive catchments closure at the basin level and declining volumes of water flowing into village level reservoirs (known locally as tanks). Flow reductions have occurred largely as a result of increased agricultural intensification over the past 10–15 years. Field levelling, field bund construction, soil water conservation measures, farm ponds, the increase in areas under horticulture and forestry and the increased abstraction and use of groundwater for irrigation are all contributing factors to reduced flows. Planning methodologies and approaches, which may have been appropriate 20 years ago for planning water harvesting within watershed development projects, are no longer appropriate today. New planning approaches are required which (1) take account of these changed flow conditions and (2) are also able to take account of externalities, which occur when actions of some affect the livelihoods of others who have no control or influence over such activities and which (3) contribute to the maintenance of agreed minimum downstream flows for environmental and other purposes.
Ian CalderEmail:
  相似文献   
634.
In subsistence farming systems of the developing world, adoption of resource-conserving practices such as integrated pest management (IPM) is often strikingly low. This has partially been ascribed to researchers’ limited understanding of how technologies develop at the interface of the systems’ social and ecological components. In Honduras (Central America), there exists concern about limited adoption and diffusion of IPM technologies in certain smallholder production systems. In this study, we determine social and ecological drivers of IPM adoption in subsistence maize production in the country’s hillside environment. Honduran small-scale maize production is typified by a key insect pest (the fall armyworm, Spodoptera frugiperda) being partly kept at bay through action of a diverse natural enemy complex, including ants, social wasps, carabid beetles, and spiders. Local agricultural landscapes, primarily shaped through shifting cultivation, provide key resources to maintain this natural enemy diversity. These local ecological conditions and related natural enemy abundance strongly influence farmers’ agroecological knowledge and pest management practices. In the meantime, farmer practices are also affected by local communication networks, which help validate and spread IPM concepts and technologies. Based on our findings, we advocate a holistic approach to improve IPM extension through mapping of agroecological opportunities, visualization of regional patterns in farmer knowledge, and associated priority setting. Local IPM capacity could be built through institutional strengthening and adaptive comanagement, while IPM training should be linked with natural resource management initiatives. These approaches may eventually improve the way IPM is delivered to small-scale farmers who operate in the ecologically diverse environments of the tropics.  相似文献   
635.
It has become increasingly apparent that global manganese (Mn) pollution to air and water is a significant threat to human health. Despite this recognition, research is only beginning to comprehend the detrimental effects of exposure. Mn, while essential, is particularly harmful to the central nervous system, and overexposure is symptomatic of several neurological disorders. At-risk populations have been identified, but it is still unclear whether typical exposure levels have any long-term consequences. Those at an elevated risk have diminished intellectual function, learning and memory, and mental development. While the overall mechanism of toxicity is undetermined, Mn has been found to induce oxidative stress, exacerbate mitochondrial dysfunction, dysregulate autophagy, and promote apoptosis, ultimately enhancing neurodegeneration. Extrapolation of this in vitro and in vivo data to humans is difficult. There is a definite need to correlate epidemiological studies with causative effects. It is imperative that research efforts endure, so threats are appropriately identified and exposure properly regulated.  相似文献   
636.

Introduction  

A Microcoleus sp. consortium, obtained from the Ebro delta microbial mat, was maintained under different conditions including uncontaminated, lead-contaminated, and acidic conditions.  相似文献   
637.
Corals and coral-associated species are highly vulnerable to the emerging effects of global climate change. The widespread degradation of coral reefs, which will be accelerated by climate change, jeopardizes the goods and services that tropical nations derive from reef ecosystems. However, climate change impacts to reef social–ecological systems can also be bi-directional. For example, some climate impacts, such as storms and sea level rise, can directly impact societies, with repercussions for how they interact with the environment. This study identifies the multiple impact pathways within coral reef social–ecological systems arising from four key climatic drivers: increased sea surface temperature, severe tropical storms, sea level rise and ocean acidification. We develop a novel framework for investigating climate change impacts in social–ecological systems, which helps to highlight the diverse impacts that must be considered in order to develop a more complete understanding of the impacts of climate change, as well as developing appropriate management actions to mitigate climate change impacts on coral reef and people.  相似文献   
638.
Increasingly, performance measurement is being used to hold federal agencies accountable, represent environmental progress, and evaluate the effectiveness of environmental programs. The need to track measurable outputs has created a tendency to present programmatic progress solely by quantifiable data, despite the inherent complexity of natural resource management. Wetlands and fire management programs are two specific environmental arenas that have come to overemphasize the tracking of acreage numbers to validate existing policy direction. In both of these arenas, we find the definition and categorization of "countable" acres to be inconsistent and unreliable. We explore this systemic flaw for both wetlands and fire programs and describe its implications for environmental policy and natural resource management more broadly. We conclude with recommendations for improved performance measurement in these arenas.  相似文献   
639.
It is now 130 years since Fritz Müller proposed an evolutionary explanation for the close similarity of co-existing unpalatable prey species, a phenomenon now known as Müllerian mimicry. Müller's hypothesis was that unpalatable species evolve a similar appearance to reduce the mortality involved in training predators to avoid them, and he backed up his arguments with a mathematical model in which predators attack a fixed number (n) of each distinct unpalatable type in a given season before avoiding them. Here, I review what has since been discovered about Müllerian mimicry and consider in particular its relationship to other forms of mimicry. Müller's specific model of associative learning involving a "fixed n" in a given season has not been supported, and several experiments now suggest that two distinct unpalatable prey types may be just as easy to learn to avoid as one. Nevertheless, Müller's general insight that novel unpalatable forms have higher mortality than common unpalatable forms as a result of predation has been well supported by field experiments. From its inception, there has been a heated debate over the nature of the relationship between Müllerian co-mimics that differ in their level of defence. There is now a growing awareness that this relationship can be mediated by many factors, including synergistic effects between co-mimics that differ in their mode of defence, rates of generalisation among warning signals and concomitant changes in prey density as mimicry evolves. I highlight areas for future enquiry, including the possibility of Müllerian mimicry systems based on profitability rather than unprofitability and the co-evolution of defence.  相似文献   
640.
Goal and Scope In order to realize surface consolidation of Pentelic marble on the Acropolis monuments, we have collected the criteria that have to be fulfilled by the methods and materials without side effects on the marbles (and other stones). When the existing methods and materials did not satisfy the requirements (criteria), we invented new ones.Methods The criteria were collected from the literature, by thermodynamic and kinetic viewpoints, by laboratory experiments and in situ observations on monuments, both in Greece and in several countries in which the various methods and materials were applied. Concerning our method of ‘Inversion of sulfation’, performed by spraying a K2CO3 solution, its concentration and its temperature were controlled in order to have a total inversion (certified by liquid crystals) of gypsum back to CaCO3. For the new material of ours, ‘Reinforced Lime’, in order to eliminate the disadvantages of plain lime (low carbonation rate, low mechanical properties of CaCO3 formed, lack of carbonation in the bulk of lime), measurements of the rate of carbonation were performed in plain lime and in lime with a different CaCO3 concentration beforehand as well as in a different CO2 environments, using DTG and XRD to measure the rate of carbonation. The detachment (kg/cm2) of marble specimens stuck by lime in each case was also measured. A microscope was also used to measure the dimensions of the grain in each case as well as ammonium citrate and thymolphthalein to certify the depth of carbonation in each case. Part of the work was communicated in an international congress.Results A table with the criteria of the selection of the methods and materials for the consolidation of Pentelic marble surfaces (and other stones) was established. None of the employed methods and materials fulfilled the criteria. Only the ‘Inversion of gypsum ‘ and the ‘Reinforced Lime’ were adopted and applied to the Acropolis monuments and to other monuments in Greece and in several other countries.Recommendation and Outlook All criteria must be used for the selection of methods and materials for the consolidation of the monument surfaces. This is why we have already studied with the same procedures, methods and materials for restoration, surface cleaning and protection.  相似文献   
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