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971.
To restore food security to a traditional African cropping system following a sudden loss of seed, genetic diversity must be re-established. This study examines the extent to which Cowpea diversity was reinstated two years after a flood disaster in Gaza Province, Mozambique. The contribution that seed from various sources made to the recovery was assessed using semi-structured interviews and morphological and molecular data. Data suggest that diversity had recovered to some extent yet there was evidence of a narrowing of the genetic base, with fewer rare alleles and differences in the distribution of allele frequencies. Although the main channels for accessing seed after the flood were seed relief and markets, these sources contributed to minimal and different diversity. It appears that diversity was regained primarily through social networking in the form of loans or gifts of seed from friends and relatives. The results of the study are discussed in relation to seed relief approaches.  相似文献   
972.
Leaves of Tendergreen bean plants exposed to atmospheric fluoride concentrations in the range 1.7 to 7.6 μg/m3 showed increased levels of enolase and catalase activity and decreased levels of pyruvate and α-ketoglutarate. Phosphoenolpyruvate carboxylase activity and oxalacetate were not affected. The leaves of Milo maize plants exposed to 5.0 μg F/m3 showed increased levels of enolase and pyruvate kinase activity and a decreased level of pyruvate. Oxalacetate and α-ketoglutarate levels were not affected. Catalase activity was increased, then decreased by IIF fumigation. The changes induced by HF were greatest six to 10 days after the start of fumigation and disappeared or decreased in magnitude during the post-fumigation period.  相似文献   
973.
974.
First-prize winner in the student paper competition conducted by the Mid-Atlantic States Section of the Air Pollution Control Association was Marvin H. Green, a graduate student at Drexel Institute of Technology and assistant chief of Philadelphia’s Air Pollution Control Section. A condensation of his paper follows.  相似文献   
975.
The problem of an investigation of the need for a regulation on organic compound emissions in the San Francisco Bay Area can be divided into two major areas: 1. Is there a need for a regulation on organic compound emissions? What is the extent of photochemical smog effects? How much control is necessary to achieve the desired effects?

2. (2) If the need exists for an organic compound regulation, can a performance type regulation be written for all types of organic compound emissions? Must the regulation be directed toward specific industries or types of emissions? Can the regulation be adequately enforced—both practically and legally?

This paper will describe the studies undertaken by the District Staff to answer the first set of questions. Work covering the second group of questions is now under investigation.  相似文献   
976.
Field tests were conducted on 82 fuel-burning installations ranging from 50 to 500 hp, fired with residual fuel oils. A flame pyrometer was used to measure peak flame temperatures. Coarse particulates were measured by impingement on adhesive paper strips inserted at right angles to the gas flow and fine particulates by filtration of the gas sample through filter paper. Both were evaluated using a standard Bacharach Scale. The tests clearly established that both coarse and fine particulate matter invariably occurred with low flame temperatures but decreased appreciably when peak flame temperatures reached approximately 2650°F; Minimum values were observed at temperatures somewhere between 2750 and 2850°F. This research was conducted as a result of the problem of acid smut and carbonaceous (ceno-sphere) fallout which appears to have increased with the advent of modern high-efficiency low-temperature heating installations and taller, cooler operating chimneys; sudden deluges of particles from the chimney serving large oil-burning plants soil clothing, pit car finishes, and damage nylon stockings and other materials.  相似文献   
977.
Informative Report No. 8 on soap and detergent manufacture is one of a series of survey reports prepared by APCA’s Tl-2 Committee on air pollution problems and control methods encountered in the chemical industry today.  相似文献   
978.
Field experience with the lead acetate impregnated paper tape sampler has indicated that large errors may arise in this method due to fading of the color of the precipitated lead sulfide spots. This fading is due to the action of light, sulfur dioxide, ozone, on other substances capable of oxidizing lead sulfide. The moisture content or relative humidity of the air sample must be maintained at an appropriate level to ensure reaction with the impregnated paper tape. The effects of the factors have been investigated in laboratory experiments with known concentrations of H2S. A number of antioxidants were studied in relation to the stability of the resultant spots to light and oxidation Orthophenyl phenol was found to be the most effective antioxidant for this purpose. A number of necessary precautions to be employed in the use of the lead acetate method are recommended and the limitations are discussed.  相似文献   
979.
Industry, government, and the public have come a long way in establishing the dialogue that is necessary if the reservations each has had of the others’ motives are to be dispelled. However, each tends to fall into a routine of accusations, charges, counter charges, and rebuttals. This paper deals with the action which must be forthcoming from industry if good community relations are to be maintained and the public interest is to be served.  相似文献   
980.
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