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961.
962.
A well-established criterion for determining the growth potential of an economy, the technology of which can be represented by a nonnegative indecomposable square matrix, is examined critically. The concept of growth upon which this criterion is established is shown to be ambiguous since the environmental repercussions of economic activity are completely ignored. Assuming that this economy possesses an antipollution technology which has hitherto been ignored, an alternative criterion to gauge growth potential in the presence of complete environmental preservation is proposed. The magnitude of the uniform rate of profit which must obtain when the economy ignores the environment if a policy of environmental preservation is to be deemed technically feasible is calculated. Finally, a number of factors which would facilitate the implementation of a policy of environmental preservation are discussed.  相似文献   
963.
In order to take account of the congestion externalities associated with increased use intensity during a given period at a low density recreational resource, it is necessary to determine the effects of alternative use levels on the expected quality of each individual's experience. This paper describes a simulation model for wilderness recreation designed to provide such measures. In order to illustrate the model it is applied to the Spanish Peaks Areas in Montana.  相似文献   
964.
Considerations are given to the simultaneous evaporation of both components in a miscible (binary) solution based on the properties of related components. Rates of evaporation of several binary systems of nonpolar organics and of polar organics with water in unstirred solutions were determined and interpreted using the model previously proposed. This study presents an approach to assess the evaporative loss of the volatile solute and solvent components from a (miscible) solution that may become a source of concern as a health risk.  相似文献   
965.
Substantial progress has been made in the production of environmental level, natural matrix, radioactivity standards of soil of low organic and low carbonate content, and of human lung and human liver. This is in response to the deliberations of the 1977 ICRM meeting at which the need for such standards was voiced and the criteria suggested. The soil samples have been reduced to optimum particle size and are ready for blending and standardization. A ten year supply of this standard should be ready in a year or less. Reducing the dried lung and liver to less than 74 μm has proven formidable because of the natural fat and oil content. Using cyrogenic milling techniques more than three quarters of the total mass of each has been reduced to the desired particle size; the balance will either be reduced or removed and we can then proceed to the final standardization.  相似文献   
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