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131.
I. S. Veselovsky K. Mursula N. G. Ptitsyna M. I. Tyasto O. S. Yakovchouk 《Geomagnetism and Aeronomy》2009,49(2):163-168
Based on an analysis of the available archived data from the Russian network of geomagnetic stations, it has been indicated that the known event of August–September 1859 was the first and the greatest event in the series of the recurrent geomagnetic storms. Similar series were repeatedly observed in the next years. These series are caused by the processes on the Sun and in the heliosphere related to the superposition of the solar wind flows. The sporadic and regular components in joint activity of the complex, including active regions and coronal holes on the rotating Sun, play the role of the Bartels M regions responsible for initiation and development of geomagnetic storms. Neither coronal holes nor active regions can separately explain observations. During interpretation, active regions and coronal holes should be considered as a unified complex. 相似文献
132.
N. N. Rabalais R. E. Turner B. K Sen Gupta D. F. Boesch P. Chapman M. C. Murrell 《Estuaries and Coasts》2007,30(5):753-772
We update and reevaluate the scientific information on the distribution, history, and causes of continental shelf hypoxia
that supports the 2001 Action Plan for Reducing, Mitigating, and Controlling Hypoxia in the Northern Gulf of Mexico (Mississippi
River/Gulf of Mexico Watershed Nutrient Task Force 2001), incorporating data, publications, and research results produced
since the 1999 integrated assessment. The metric of mid-summer hypoxic area on the LouisianaTexas shelf is an adequate and
suitable measure for continued efforts to reduce nutrients loads from the Mississippi River and hypoxia in the northern Gulf
of Mexico as outlined in the Action Plan. More frequent measurements of simple metrics (e.g., area and volume) from late spring
through late summer would ensure that the metric is representative of the system in any given year and useful in a public
discourse of conditions and causes. The long-term data on hypoxia, sources of nutrients, associated biological parameters,
and paleoindicators continue to verify and strengthen the relationship between the nitratenitrogen load of the Mississippi
River, the extent of hypoxia, and changes in the coastal ecosystem (eutrophication and worsening hypoxia). Multiple lines
of evidence, some of them representing independent data sources, are consistent with the big picture pattern of increased
eutrophication as a result of long-term nutrient increases that result in excess carbon production and accumulation and, ultimately,
bottom water hypoxia. The additional findings arising since 1999 strengthen the science supporting the Action Plan that focuses
on reducing nutrient loads, primarily nitrogen, through multiple actions to reduce the size of the hypoxic zone in the northern
Gulf of Mexico. 相似文献
133.
The annealing characteristics of fission tracks in allanite have been studied. All the tracks in the mineral fade at 720° C for one hour heating. The activation energy of allanite ranges from 1.4 to 3.4 eV. 相似文献
134.
K. N. Khattri 《Journal of Earth System Science》1999,108(2):87-92
Long-term conditional probabilities of occurrence of great earthquakes along the Himalaya plate boundary seismic zone have
been estimated. The chance of occurrence of at least one great earthquake along this seismic zone over a period of 100 years
(beginning the year 1999) is estimated to be about 0.89. The 100-year probability of such an earthquake occurring in the Kashmir
seismic gap is about 0.27, in the central seismic gap about 0.52 and in the Assam gap about 0.21. The 25-year probabilities
of their occurrence in these gaps are 0.07, 0.17, and 0.05 respectively. These probability estimates may be used profitably
to assess the seismic hazard in the Himalaya and the adjoining Ganga plains. 相似文献
135.
Both pyruvic and α-ketobutyric acids are formed during heating experiments with modern Chione shells. These α-keto acids are also present in fossil specimens. These findings provide additional evidence that the dehydration reaction of free serine and threonine or the β-elimination reaction of peptide bound serine and threonine occurred in fossil materials. These experiments suggest that the formation of α-keto acids occurs early in protein diagenesis. A large fraction of the α-keto acids which were formed have been lost either by subsequent reactions or by diffusion out of the shell matrix. 相似文献
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139.
Mass spectra in the range 2 ≦ M/Q ≦ 3 provided by a high resolution mode of the ISEE-3 Plasma Composition Experiment were evaluated for three selected periods during early 1980. The observed Ne/O ratios are compatible with estimated solar abundance ratios. In two of the three periods, the He/Ne-ratios agree with the Apollo foil results. Freezing-in temperatures for oxygen are similar to those obtained by other groups. Possible reasons for an unexpectedly high flux at M/Q = 2.4 are discussed. 相似文献
140.