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71.
Sections of two pollarded parkelms (Ulmus glabra) from Damsgaard, Bergen, west Norway have been studied. Changes in annual ring-width are attributed partly to management, namely pollarding, and partly to pathogenic attacks, probably by Ceratocystis ulmi. The oldest attack on the trees dates back to 1826: so far the oldest known record of Dutch elm disease in Norway. Pollarding may be an important factor in attacks by the pathogen within parkelms. A possible relationship between pollarding, the pathogen and the Neolithic elmfall is suggested. 相似文献
72.
Although the principles and the necessity for good laboratory practice (GLP) guidelines to confirm the credibility, integrity, and quality of non-clinical laboratory studies have been known for more than a decade, culture collection activities are not subject to them. Because of recent advances in biotechnology, culture collections face increased demands not only for quality cultures but also current information. When applied in culture collections, GLP guidelines prove to be an excellent management tool as well as a cost-effective system of providing authentic and reliable microbial and cell cultures and associated data. 相似文献
73.
74.
Sarah J. Holden D. Layne Coppock Mulugeta Assefa 《Human ecology: an interdisciplinary journal》1991,19(1):35-59
Surveys of pastoral households in a semi-nomadic Borana community during 1987–1988 were used to test the hypothesis that poorer families living closest to a market town would be most affected by the enhanced opportunity to sell dairy products, which would intensify competition between people and calves for milk and have negative implications for calf management. These poorer families indeed reported the highest rates of milk offtake per cow, and the milk increment was probably sold to purchase more grain for human consumption at the expense of milk intake for the calf. Consequently, this strategy may increase the susceptibility of malnourished calves to disease, especially those from lower-producing dams. Benefits of improved human energy intake from grain and retention of livestock capital must be weighed against risks of calf death and possible malnutrition of people from milk restriction when assessing dairy marketing trade-offs that are most acute for the poor. Opportunity to sell dairy products at favorable terms of trade helps the poorest people survive, and their risks could be mitigated by policies that facilitate grain marketing in the rangelands and interventions that improve calf feeding management, diversify human diets, and create alternative opportunities for women to generate income. The households postulated to be most at risk were identified from a complex, but logical, interaction among factors of distance to market, household wealth, and the quality of milking cows held. This indicates that targeting such needy groups for development assistance may require a more detailed and interdisciplinary analysis of production systems than is commonly practiced. 相似文献
75.
On nonparametric discrimination using density differences 总被引:2,自引:0,他引:2
76.
Residuals for relative risk regression 总被引:2,自引:0,他引:2
77.
Regression analysis based on stratified samples 总被引:1,自引:0,他引:1
78.
Estimation in linear models with censored data 总被引:1,自引:0,他引:1
79.
Longitudinal data analysis using generalized linear models 总被引:186,自引:0,他引:186
80.
Phenamiphos (6.7 kg a.i./ha) was applied via an irrigation simulator to squash at planting (AP) and 2 weeks after planting (PP), and to corn AP and 1 week PP to manage root-knot nematodes (Meloidogyne incognita). The nematicide was applied with 0.25, 0.64, 1.27, and 1.91 cm surface water/ ha to a Lakeland sand in which the soil moisture was at or near field capacity. Based on efficacy and crop response, no additional benefits resulted when phenamiphos was applied in volumes of water greater than 0.25 crn/ha. The cost of applying each 0.25 cm of water over a hectare is approximately $1.08, or a 92% reduction in nematicide application cost over conventional methods ($13.50/ha). Low root-gall indices and high yields from squash and corn indicate more effective nematode management when phenamiphos was applied AP rather than PP. Results from this method of applying phenamiphos suggest that certain nematicides could be used as salvage alternatives when nematodes are detected in crops soon after planting. For multiple-pest management, nematicides, other compatible biocides, and fertilizers could be applied simultaneously with sprinkler irrigation. 相似文献