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241.
Consumer's choice of food can influence the environment. In Sweden, in common with many other countries, consumers need to be given information so they can make environmentally informed shopping choices. However, what is the most advantageous dietary choice to lower greenhouse emissions? This study investigates the greenhouse gas emissions associated with food production for food consumed in Sweden annually. Specifically, this study compares greenhouse gas emissions associated with a nutritionally and environmentally sustainable diet with the average consumption of food in Sweden 1999. The study concludes that the change in energy use and greenhouse gas emission associated with this change of diet is negligible. Lowering greenhouse gas emissions by changing food production processes results in more profound changes than teaching consumers to make environmentally correct choices. There is a basic need for a reduction or a replacement of the use of fossil fuels to produce and distribute our food in order to reach any significant reduction in the emission of greenhouse gases. Swedish agricultural policy does not provide ways to reduce greenhouse gas emissions. In Sweden therefore there is an immediate need to design policy instruments with the primary aim of reducing the greenhouse effect.  相似文献   
242.
Parental investment decision rules: a test in bluegill sunfish   总被引:5,自引:1,他引:4  
Summary We review parental investment decision theory and provide an experimental test of the decision rule used by male bluegill sunfish (Lepomis macrochirus) in allocating parental investment to their young. The alternative decision rules tested are: (1) invest according to brood size (number) only; (2) invest according to past investment only; (3) invest according to both brood size and past investment; and (4) invest according to neither brood size nor past investment. By manipulating brood size independently of a male's cumulative investment in the brood, and by measuring each male's defensive behavior against a model predator, we found that male bluegill invest according to both brood size and past investment. This result is consistent with recent theory that past parental investment devalues adult future reproductive value, and that animals should therefore invest according to the value of their brood relative to that of their own expected future reproduction.  相似文献   
243.
A survey of cesium residues in fish from the Savannah River near the Savannah River Nuclear Plant was undertaken in 1983. Fish tissues, bone, fin, and muscle were incubated by the wet disgestion method for analysis. Seventeen fish samples were analyzed by flame atomic absorption spectrophotometry procedure to determine cesium content. It was found that cesium concentration levels were consistently higher in the bones and fins than in muscles of all fish species. It seems that cesium concentration levels were relatively higher in fins than in bones. Cesium concentration levels in muscle tissues were negligible in all fish species.  相似文献   
244.
245.
The particle track analysis and α-spectrometric techniques have been applied to a comparative study of excess 230Th dating of three deep-sea cores from the Eastern Atlantic. Both methods yield similar sediment accumulation rates. Limitations of the α-track phase of the particle track detection process, arising from the non-specific determination of 230Th and from the mobility of some alpha-emitting daughters, suggest that details of the sedimentation record may fail to be identified. The conventional radiochemical technique, on the other hand, specifically isolates all the radionuclides of interest but at the expense of a more complex experimental procedure and a longer sample processing time. The combined particle track technique (i.e. α and fission track analyses) therefore seems excellently suited to a complementary role in tandem with the α-spectrometric method of 230Th dating. Uranium determination by the fission track technique is accurate and rapid, showing good agreement with the α-spectrometric method.  相似文献   
246.
A survey of trace element residues in fish from the Savannah River near Savannah River Nuclear Plant was undertaken in 1982. Fish muscle tissue was incubated by the wet digestion method. Fifteen trace elements were determined by flame atomic absorption spectrophotometry analysi of the digests. It was found that As, Se, Mg, Hg, Ca, Zn, and Fe levels were relatively higher than Pb, Cd, Ni, Co, Cr, and Mn in all fish species. In addition, in all fish species it seems that Pb, Cd, Ni, Co, Cr, and Mn levels were relatively higher than Cs and Cu. Cs and Cu levels were negligible in all fish species analyzed. Trace element levels found in these fish species were not high enough to render them dangerous for human consumption.  相似文献   
247.
The Klippel-Trenaunay-Weber syndrome is a complex developmental disorder of the vascular and skeletal systems. While many features of the syndrome are congenital, it has not been diagnosed often before birth. This paper describes a case of Klippel-Trenaunay-Weber syndrome diagnosed at 19 weeks' gestation on the basis of sonographic findings and family history. The clinical variability of the syndrome is emphasized and the importance of family history in differential diagnosis is stressed.  相似文献   
248.
Factors found to be associated with pregnancy loss after transcervical CVS were race (higher for non-white), history of spontaneous abortion, unplanned pregnancy, history of spotting or bleeding during the pregnancy prior to CVS, and placental position (higher for fundal or lateral locations). Whether the increase in loss risk is due to the factor, per se, or the factor plus the CVS cannot be determined due to the lack of appropriate control data.  相似文献   
249.
Several snake tissue samples and one set of snake eggs were collected and analyzed for 2,3,7,8-tetrachlorodibenzo-p-dioxin. The isomer-specific analysis was performed using fused silica GC combined with atmospheric pressure ionization MS. The results ranged from a low of 38 parts-per-trillion (ppt) to high levels over 500 ppt.  相似文献   
250.
The crystal structure of octachlorodibenzo-p-dioxin (OCDD) was determined and compared with the calculated geometry obtained by the semi-empirical modified neglect of diatomic overlap (MNDO) method. Experimental and calculated geometries for OCDD show excellent agreement.  相似文献   
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