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排序方式: 共有349条查询结果,搜索用时 46 毫秒
341.
Efficient and effective disaster management will prevent many hazardous events from becoming disasters. This paper constitutes the most comprehensive document on the natural disaster management framework of Cameroon. It reviews critically disaster management in Cameroon, examining the various legislative, institutional, and administrative frameworks that help to facilitate the process. Furthermore, it illuminates the vital role that disaster managers at the national, regional, and local level play to ease the process. Using empirical data, the study analyses the efficiency and effectiveness of the actions of disaster managers. Its findings reveal inadequate disaster management policies, poor coordination between disaster management institutions at the national level, the lack of trained disaster managers, a skewed disaster management system, and a top‐down hierarchical structure within Cameroon's disaster management framework. By scrutinising the disaster management framework of the country, policy recommendations based on the research findings are made on the institutional and administrative frameworks.  相似文献   
342.
Habitat selection requires choice, which differentiates it from habitat use, and choice, in turn, is dependent upon the responses of organisms to the environmental, social, and other cues that they perceive. Habitat selection by the gopher tortoise (Gopherus polyphemus) was investigated by translocating tortoises and monitoring their movements within two sites in central Florida. The first site supported a stable preponderance of high-quality habitat, and tortoises avoided areas with a dense tree canopy cover caused by fire exclusion. The second site was badly invaded by an introduced weed, and tortoises avoided areas where the weed had formed a dense monoculture. At both sites, individuals appeared to be responding to visual cues to avoid areas that were relatively dark. In landscapes with relatively large amounts of high-quality habitat, this avoidance behavior serves the gopher tortoise well by keeping individuals within the dominant habitat type. In degraded areas, high-quality habitat often becomes increasingly uncommon, and the avoidance behavior exhibited by the tortoises will result in individuals becoming confined to small patches, causing a significant reduction in fitness and hence questioning their long-term survival in such areas. The results from our study show that in order to maintain viable tortoise populations in areas increasingly subjected to human fragmentation and degradation, it is crucial not only to suppress tree canopy cover continually and prevent invasion by exotic weeds, but also to be mindful that the avoidance behavior of the gopher tortoise could prevent individuals from fully occupying a high-quality habitat in response to restoration and management efforts.  相似文献   
343.
Colonial epifauna are vulnerable to the effects of bottom fishing, but impacts on the life histories of these non-target animals have not been examined extensively. Dredging potentially impairs sexual reproduction by invoking regeneration and induces clonality by severing colonies or through the abortion of damaged modules. This study investigated the potential for commercial-scale scallop dredging to alter sexual and asexual (clonal) reproduction in the hydroid Sertularia cupressina. In total, 1,071 colonies from 104 epizoic microhabitats (upper valves of live scallops relatively undisturbed by fishing) and 75 epilithic microhabitats (cobbles more severely disturbed by fishing) were collected from 53 to 94-m depths in the Bay of Fundy (Atlantic Canada). Colony abundance, injury frequency (proportion of colonies with sealed, snapped off stems), percentage of fertile colonies and sexual fecundity (number of gonophores and gonophore dimensions) were measured on all substrata. Ten randomly amplified polymorphic DNA (RAPD) primers were used to estimate clonal diversity. Field experiments found no significant effect of microhabitat differences between scallop and cobble substrata on fecundity and clonality in S. cupressina, while experimentally-induced injuries suppressed the percent of fertile colonies. On the fishing grounds, colonies on scallop valves were more abundant and sexually fertile than their counterparts on cobble, and all were sexually derived. In contrast, colonies on cobbles had a greater percentage of injury, were less fertile and were frequently clonally-derived. Impacts of fishing-related injuries on reproduction in colonial epifauna have been overlooked, yet the long-term consequences of such impacts could result in reduced adaptability, recruitment and recovery potential of these and dependent organisms.Communicated by R.J. Thompson, St. Johns  相似文献   
344.
In 1994, the U.S. Department of Energy (DOE) initiated a contract reform program intended to strengthen oversight capabilities and encourage the creation of contract and incentive structures, which would effectively facilitate the treatment of onsite contamination and waste. The remedia‐tion and disposal of these legacy wastes is the core of the Department's environmental manage‐ment mission (Government Accountability Office [GAO], 2003). Despite a concerted effort toward achieving the goals of the reform, progress has been slow. Many projects continue to necessitate cost and time extensions above those originally agreed upon. Although the Department insti‐tuted an accelerated cleanup program in 2002, promising to shave some $50 billion and 35 years from its earlier cost and schedule projections, there have been delays in critical project areas that call into question the attainability of the proposed reductions (GAO, 2005). Numerous explana‐tions have been offered as to why achieving these goals has proven so difficult, many of which have concluded that flawed contracting practices are to blame. This article concludes that the root of the problem is much deeper and that the organizational criticisms aimed at DOE are as much a legacy as the waste itself. Although the focus of this article is on large former nuclear weapons sites, these types of contracting and organizational issues are often found at other gov‐ernment and private complex hazardous waste sites. © 2006 Wiley Periodicals, Inc.  相似文献   
345.
The Consortium for Risk Evaluation with Stakeholder Participation (CRESP) was asked by the United States Department of Energy (US DOE) to consider the root causes of remediation projects that fail to entirely achieve their goals and then to offer suggestions to assist the Department. To begin this project, CRESP held several meetings at which the group defined problematic outcomes, the early symptoms of problematic outcomes, and the root causes of failing to meet expectations. The five root causes are complex science, engineering, and technology; ambiguous economics; project management shortcomings; political processes and credibility; and history and organizational culture. This article, while focusing on the US DOE, provides a larger context for many remediation projects that have failed to entirely live up to their sponsors' expectations. © 2007 Wiley Periodicals, Inc.  相似文献   
346.
A Vegetation-Based Method for Ecological Diagnosis of Riverine Wetlands   总被引:2,自引:0,他引:2  
/ The management of riverine wetlands, recognized as a major component of biodiversity in fluvial hydrosystems, is problematic. Preservation or restoration of such ecosystems requires a method to assess the major ecological processes operating in the wetlands, the sustainability of the aquatic stage, and the restoration potential of each riverine wetland. We propose a method of diagnosis based on aquatic macrophytes and helophytes. Plant communities are used because they are easy to survey and provide information about (1) the origin of a water supply (i.e., groundwater, seepage, or surface river water) and its nutrient content, (2) effects of flood disturbances, and (3) terrestrialization processes. The novelty of the method is that, in contrast to available typologies, it is based on the interference of gradients resulting from several processes, which makes it possible to predict wetland sustainability and restoration potential. These predictions result from knowledge of the processes involved in terrestrialization, i.e., the influence of flood disturbances, occurrence of groundwater supplies, trophic degree, and water permanency of the habitat during a yearly cycle. The method is demonstrated on five different river systems.  相似文献   
347.
A novel estuarine flow model is proposed. It provides some two-dimensional features while using an essentially one-dimensional approach. The model is applied to the Upper Delaware Estuary, and is shown to match available field data with acceptable accuracy. The model is shown to be numerically stable and reasonably mass conservative.  相似文献   
348.
The Agricultural Conservation Program (ACP), is undergoing a new, rigorous evaluation to determine its effectiveness in conserving the Nation's agricultural soils and waters. ACP deals with many types of conservation practices, but the focus here is on the evaluation of soil and water related practices. ACP has depended heavily on the State and private forestry services, Soil Conservation Service, and the Cooperative Extension Services, for technical expertise. Thus, the process is an evaluation of the effectiveness of a “team of agencies,” as well as of the program itself. Results of the evaluation have helped to develop new thrusts which have moved ACP further into the position of treating the total conservation problem. Phase I has its limitations. It did not address the impact of wind erosion, water quality, change in productive capacity, soil quality, wildlife habitat, off site and farm income impacts. It does show that ACP has and is doing a very good job in meeting its stated purposes. It is clear that ACP's effectiveness can be improved with more and better advanced planning and more intensive use of soil maps, the USLE, and other scientific tools. ACP is headed in this direction.  相似文献   
349.
Attention is described as the ability to process selectively one aspect of the environment over others. In this study, we characterized horses’ spontaneous attention by designing a novel visual attention test (VAT) that is easy to apply in the animal’s home environment. The test was repeated over three consecutive days and repeated again 6 months later in order to assess inter-individual variations and intra-individual stability. Different patterns of attention have been revealed: ‘overall’ attention when the horse merely gazed at the stimulus and ‘fixed’ attention characterized by fixity and orientation of at least the visual and auditory organs towards the stimulus. The individual attention characteristics remained consistent over time (after 6 months, Spearman correlation test, P < 0.05). The validity of this novel test as a predictor of individual attentional skills was assessed by comparing the results, for the same horses, with those obtained in both a ‘classical’ experimental attention test the ‘five-choice serial reaction time task’ (5-CSRTT) and a work situation (lunge working context). Our results revealed that (i) individual variations remained consistent across tests and (ii) the VAT attention measures were not only predictive of attentional skills but also of learning abilities. Differences appeared however between the first day of testing and the following test days: attention structure on the second day was predictive of learning abilities, attention performances in the 5-CSRRT and at work. The VAT appears as a promising easy-to-use tool to assess animals’ attention characteristics and the impact of different factors of variation on attention.  相似文献   
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