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John R. Percy 《Experimental Astronomy》1994,5(1-2):121-128
The role of amateurs and small-scale equipment in astronomical photometry is reviewed. The value of suitably selected projects for both research and educational purposes is stressed. Recent technical developments are noted, and a brief extrapolation to possible future arrangements included.Keynote address at the conference 相似文献
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A dramatic sinkhole collapse measuring some 100 feet in diameter by 41 feet deep occurred suddenly in the Borough of Macungie
on June 23, 1986. The sinkhole collapse resulted in a major disruption of traffic, utility services, as well as a major health
and safety hazard. Continual growth of the sinkhole could have resulted in almost certain damage or loss to more than 17 residences
adjacent to the sinkhole collapse. Stabilization and repair costs totaled some $450,000 and required almost three months to
restore utility services, roadway, and parking areas. 相似文献
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Abstract Triangulation from paired sferics (100 ± 50 kHz) received at stations 57 km apart gave 42 map locations of lightning flashes belonging to a thunderstorm well‐defined on weather radar. This storm was one of many in a long line along the leading edge of a band of light stratiform precipitation (snow above 3 km). The band was 9 km high and 60 km wide, and the storms were embedded in it. The convective region of the storm studied had a north‐south extent of 20 km, the east‐west extent averaging two‐thirds as much. Cumulus heights progressed from 3 km on the west to 7 ± 1 km on the east. Two‐thirds of the lightning flashes were in the convective region. The remaining third were in 160 km2 of the light stratiform precipitation immediately west of it. 相似文献
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The effects of exposure to seawater dispersions of northern crude oils on the locomotory activity of two Arctic marine invertebrates, the amphipod Onisimus affinis and the coelenterate Halitholus cirrattus have been examined. Low concentrations of the oils significantly impair activity in both species. The ecological implications of such sublethal effects may be important. 相似文献
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Percy H. Dougherty 《The Professional geographer》1990,42(4):494-495