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21.
Modern civilisation explores and penetrates the interior of the Earth's crust, recovers from it and stores into it solids, fluids and gases to a hitherto unprecedented degree. Management of underground structures such as boreholes or reservoirs take into account the existing stress either to take advantage of it or at least to minimise the effects of man-made stress. This paper presents the World Map of Tectonic Stresses (in short: World Stress Map or WSM) as a fundamental geophysical data-base. The impact of the WSM is pointed out: in the context of global tectonics, in seismic hazard quantification and in a wide range of technological problems in industrial applications such as oil reservoir management and stability of underground openings (tunnels, boreholes and waste disposal sites). 相似文献
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A number of hypotheses have been proposed to explain the evolution of multiple mating in the honeybee queen. In particular,
the consequences of reduced intracolonial relatedness provide plausible explanations for multiple mating with up to ten drones,
but fail to account for the much higher mating frequencies observed in nature. In this paper, we propose an alternative mechanism
which builds on non-linear relationships between intracolonial frequencies in genotypic worker specialization and colony fitness.
If genes for any worker specialization confer an advantage on colony fitness only when they are rare, this would require a
stable mix of sperm from a few drones which contribute that trait, and many which do not. To ensure both specific, low within-colony
proportions of “rare specialist” genes, and to reduce random variation of these proportions would require mating with high
numbers of drones. The quantitative implementation shows that moderate to very high numbers of matings are required to exploit
colony advantages from genotypic allocation of workers to rare tasks. Extreme polyandry thus could result from colony selection
dependent on the intracolonial frequency of rare genetic specialists.
Received: 30 January 1998 / Accepted after revision: 7 October 1998 相似文献