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71.
72.
Environmental degradation, competition for resources, increasing food demands, and the integration of agriculture into the
international economy threaten the sustainability of many food production systems. Despite these concerns, the concept of
sustainable food production systems remains unclear, and recent attempts to appraise sustainability have been hampered by
conceptual inconsistencies and the absence of workable definitions. Six perspectives are shown to underpin the concept. Environmental
accounting identifies biophysical limits for agriculture. Sustained yield refers to output levels that can be maintained continuously.
Carrying capacity defines maximum population levels that can be supported in perpetuity. Production unit viability refers
to the capacity of primary producers to remain in agriculture. Product supply and security focuses on the adequacy of food
supplies. Equity is concerned with the spatial and temporal distribution of products dervied from resource use. Many studies
into sustainable agriculture cover more than one of these perspectives, indicating the concept is complex and embraces issues
relating to the biophysical, social, and economic environments. Clarification of the concept would facilitate the development
of frameworks and analytical systems for appraising the sustainability of food production systems.
LRRC Contribution No. 90–46. 相似文献
73.
74.
Chris Bryant 《补救:环境净化治理成本、技术与工艺杂志》1995,6(1):111-113
75.
Ted L. Napier Elizabeth G. Bryant Steve McClaskie 《Journal of the American Water Resources Association》1983,19(5):811-819
ABSTRACT This paper examines the social impact of reservoir construction on a rural community group located in the urban fringe of a major metropolitan area in central Ohio. The study data were collected at three intervals over a ten-year period (1970, 1974, 1980). Evaluation of resident opinions in the affected community revealed significant attitude differences over time for four of the five variables measured. The findings revealed that the study group desired more social stability but had accommodated the changes experienced to date. Responses to the attitude scales showed that the people in the study group were well integrated and were closely identified with each other at all three test periods. Attitudes toward the lake project were significantly more positive over time, and in 1980 the collective community group held a basically neutral attitude about the lake. The development agency was also perceived more positively over time. 相似文献
76.
Incident reporting systems are playing an increasingly important role in the development and maintenance of safety-critical applications. The perceived success of the FAA's Aviation Safety Reporting System (ASRS) and the FDA's MedWatch has led to the establishment of similar national and international schemes. These enable individuals and groups to report their safety concerns in a confidential or anonymous manner. Unfortunately, many of these systems are becoming victims of their own success. The ASRS and MedWatch have both now received over 500,000 submissions. In consequence, the administrators of incident reporting systems increasingly rely upon software tools to support the administration of their systems. In the past, these systems have relied upon ad hoc applications of conventional database technology. However, there are several reasons why this technology is inadequate for many large-scale reporting schemes. In particular, the problems of query formation often result in poor precision and recall. This, in turn, has profound implications for safety-critical applications. Users may fail to identify similar incidents within national or international collections. These ad hoc approaches also neglect the opportunities provided by recent developments in computer assisted interviewing and in the monitoring of retrieval activities to build models of user behavior. These techniques offer a number of potential benefits. For instance, it is possible to automatically detect potential biases in the way that investigators analyze particular incidents. 相似文献
77.
Rational, cost-effective provision of mission-critical environmental management information remains elusive for almost all large enterprises. Even among the best performing companies—best performing from the perspectives of profitability, quality and/or environmental stewardship—environmental management information systems (EMIS) are usually comprised of dozens to hundreds of individual, isolated applications that require costly data capture, training, and maintenance. This article, the first of two, will discuss ways to coordinate information infrastructures with strategic goals and business processes. 相似文献
78.
Chris FitzGerald 《环境质量管理》1994,4(2):21-33
Successful implementation of environmental management information systems (EMIS) has become essential to the success of total quality environmental management (TQEM) programs. Effective TQEM programs will be early indicators of which companies survive and thrive in today's competitive business environment. Highly competitive industries such as chemicals, electronics, and oil and gas are becoming very effective in cooperating to develop metrics, models, and tools that are based on business processes rather than regulatory edicts. Now electric power companies, newly exposed to market competition, are starting to develop and implement these metrics, standards, and tools. That industry provides a model for joining TQEM and EMIS. 相似文献
79.
Rapid interphase analysis for prenatal diagnosis of translocation carriers using subtelomeric probes
Mark J. Pettenati Chris Von Kap-Herr Bethy Jackle Peggy Bobby Philip Mowrey Stuart Schwartz P. Nagesh Rao Jon Rosnes 《黑龙江环境通报》2002,22(3):193-197
Interphase fluorescence in situ hybridization (FISH) has become an accepted laboratory technique for the rapid and preliminary prenatal assessment of chromosome aneuploidy. The introduction of subtelomeric FISH probes now allows for the molecular–cytogenetic analysis of terminal chromosome rearrangements. In a prospective study, we examined the prenatal use of subtelomeric probes on interphase cells to rapidly detect the carrier status of a fetus when a parent carried a known reciprocal or Robertsonian chromosome translocation. Three of the cases were identified as being abnormal. All cases were confirmed by routine cytogenetic analysis. These findings clearly demonstrated the utility of this technique and these probes to rapidly and correctly identify balanced and unbalanced chromosome anomalies of a fetus that could result from parental translocations. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
80.
Beekman M Good G Allsopp MH Radloff S Pirk CW Ratnieks FL 《Die Naturwissenschaften》2002,89(10):479-482
In the Cape honey bee Apis mellifera capensis, workers lay female eggs without mating by thelytokous parthenogenesis. As a result, workers are as related to worker-laid eggs as they are to queen-laid eggs and therefore worker policing is expected to be lower, or even absent. This was tested by transferring worker- and queen-laid eggs into three queenright A. m. capensis discriminator colonies and monitoring their removal. Our results show that worker policing is variable in A. m. capensis and that in one colony worker-laid eggs were not removed. This is the first report of a non-policing queenright honey bee colony. DNA microsatellite and morphometric analysis suggests that the racial composition of the three discriminator colonies was different. The variation in policing rates could be explained by differences in degrees of hybridisation between A. m. capensis and A. m. scutellata, although a larger survey is needed to confirm this. 相似文献