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Diffusion in mantle liquids: Ion dynamics |
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Eos, Transactions American Geophysical Union,
Volume 63,
Issue 52,
1982,
Page 1345-1345
Peter M. Bell,
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摘要:
New calculations by ion dynamics computer simulation methods suggest that the component diffusion coefficients of many silicate liquids show anomalous pressure dependences. At high pressures of several hundred kilobars the viscosities of certain silicate melts decrease strongly and the ion diffusivities of their components increase sharply.Formerly, the question of diffusion coefficients in silicate liquids in the earth was answered easily: there was little or, essentially, no diffusion. Stirring, mixing, and density‐driven upwelling processes were thought to be effective in transporting ions in silicate liquids, but the excess of free energy provided by temperature or compositional gradients in magmatic‐liquids were considered to be insufficient to drive ionic diffusional processes within appropriate time scales. In laboratory experiments, for example, if two chemically miscible silicate liquids of differing composition are placed in contact along a plane surface, they remain essentially unchanged. After hundreds of hours of contact there is no more than microscale chemical diffusion obse
ISSN:0002-8606
DOI:10.1029/EO063i052p01345-01
年代:1982
数据来源: WILEY
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[Comment on “Open scientific communication urged” “Technology transfer–A growing problem” and “Update: Science and security”] DOD funds |
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Eos, Transactions American Geophysical Union,
Volume 63,
Issue 52,
1982,
Page 1346-1346
Joseph Walder,
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PDF (149KB)
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摘要:
The most significant observation to be made about the recent (Oct. 5, 12, and 19) news items inEoson ‘technology transfer’ is that several key issues were never even addressed. For example, actual or potential censorship of technical papers is reported to have caused ‘considerable clamor within the scientific community,’ yet never once were directly relevant questions asked. For example: Should academic researchers depend upon military funding for their support? Does acceptance of financial support from military sources make individuals and institutions dependent clients of the Pentagon? In this context it is ironic to note that the Oct. 12 issue ofEosalso featured an article entitled ‘DOD to Fund Major Instruments,’ describing the manner in which DOD intends to spend $150 million to equip university laboratories in the next 5 years. This article noted explicitly that ‘For example, computers obtained with the program funds are to be usedonlyfor defense‐related projects’ (my emphasis). It seems that scientists should reflect a bit about a funding system that channels dollars thr
ISSN:0002-8606
DOI:10.1029/EO063i052p01346-01
年代:1982
数据来源: WILEY
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Isotope geochemists meet in Japan |
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Eos, Transactions American Geophysical Union,
Volume 63,
Issue 52,
1982,
Page 1348-1349
E. Ito,
R. S. Harmon,
D. Elmore,
K. Nishiizumi,
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PDF (329KB)
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摘要:
The Fifth International Conference on Geochronology, Cosmochronology, and Isotope Geology was held from June 27–July 2, 1982 in Nikko, Japan. These conferences are held every 4 years to review progress in geochronology and isotope geochemistry and to discuss results of the application of isotopic techniques to problems in the earth and space sciences. The first two, held in Canada in 1966 and Switzerland in 1970, were concerned with geochronology only. In 1974 the meeting in France expanded to include cosmochronology and stable isotopes. The subsequent 1978 meeting in the United States, and this year's meeting in Japan, followed that format. At the Nikko meeting the distribution of papers among the three general themes were: geochronology, 21%; cosmochronology, 23%; isotope geology, 56%, indicating a distinct trend toward the use of isotopes as tracers to solve geological and geochemical problems in both the earth and space sciences. The increasing tendency to consider coupled isotope‐chemical systematics in such studies indicates that the next meeting, to be held in Cambridge, England in the summer of 1986, will probably formally integrate trace‐element geochem
ISSN:0002-8606
DOI:10.1029/EO063i052p01348
年代:1982
数据来源: WILEY
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