共查询到20条相似文献,搜索用时 15 毫秒
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J Cohen 《Science (New York, N.Y.)》2012,337(6091):176-177
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The Sierra Madre fault, along the southern flank of the San Gabriel Mountains in the Los Angeles region, has failed in magnitude 7.2 to 7.6 events at least twice in the past 15,000 years. Restoration of slip on the fault indicated a minimum of about 4.0 meters of slip from the most recent earthquake and suggests a total cumulative slip of about 10.5 meters for the past two prehistoric earthquakes. Large surface displacements and strong ground motions resulting from greater than magnitude 7 earthquakes within the Los Angeles region are not yet considered in most seismic hazard and risk assessments. 相似文献
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R D Stewart E D Baretta L R Platte E B Stewart J H Kalbfleisch B Van Yserloo A A Rimm 《Science (New York, N.Y.)》1973,182(119):1362-1364
To determine the carbon monoxide exposure experienced by the residents of Chicago, Los Angeles, Milwaukee, and New York, venous blood samples were obtained from adults at arbitrarily chosen blood bank collection sites in the four cities and analyzed for circulating carbon monoxide, carboxyhemoglobin. For comparative purposes, blood was obtained from volunteers breathing carbon monoxide-free air and was found to contain 0.45 percent carboxyhemoglobin. By contrast a high percentage of all the nonsmoking blood donors breathing city air had carboxyhemoglobin saturations greater than 1.5 percent, which indicated that exposure to carbon monoxide in excess of that permitted by the quality standards of the Clean Air Act of 1971 was widespread and occurring regularly. 相似文献
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Predicting soil depth in a large and complex area using machine learning and environmental correlations 下载免费PDF全文
Soil depth is critical for eco-hydrological modeling, carbon storage calculation and land evaluation. However, its spatial variation is poorly understood and rarely mapped. With a limited number of sparse samples, how to predict soil depth in a large area of complex landscapes is still an issue. This study constructed an ensemble machine learning model, i.e.,quantile regression forest, to quantify the relationship between soil depth and environmental conditions. The model was then combined with ... 相似文献
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Geologic and palynological evidence for rapid sea level change approximately 3400 and approximately 2000 carbon-14 years ago (3600 and 1900 calendar years ago) has been found at sites up to 110 kilometers apart in southwestern British Columbia. Submergence on southern Vancouver Island and slight emergence on the mainland during the older event are consistent with a great (magnitude M >/= 8) earthquake on the Cascadia subduction zone. The younger event is characterized by submergence throughout the region and may also record a plate-boundary earthquake or a very large crustal or intraplate earthquake. Microfossil analysis can detect small amounts of coseismic uplift and subsidence that leave little or no lithostratigraphic signature. 相似文献
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Michelson PF 《Science (New York, N.Y.)》2008,322(5901):529
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The spacial distribution of seismically induced liquefaction features discovered along the Atlantic seaboard suggest that during the last 2000 to 5000 years, large earthquakes (body wave magnitude, m(b) >/= 5.8 +/- 0.4) in this region may have been restricted exclusively to South Carolina. Paleoliquefaction evidence for six large prehistoric earthquakes was discovered there. At least five of these past events originated in the Charleston, South Carolina, area, the locale of a magnitude 7+ event in 1886. During the past two millennia, large events may have occurred about every 500 to 600 years. 相似文献
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Old trees growing along the San Andreas fault near Wrightwood, California, record in their annual ring-width patterns the effects of a major earthquake in the fall or winter of 1812 to 1813. Paleoseismic data and historical information indicate that this event was the "San Juan Capistrano" earthquake of 8 December 1812, with a magnitude of 7.5. The discovery that at least 12 kilometers of the Mojave segment of the San Andreas fault ruptured in 1812, only 44 years before the great January 1857 rupture, demonstrates that intervals between large earthquakes on this part of the fault are highly variable. This variability increases the uncertainty of forecasting destructive earthquakes on the basis of past behavior and accentuates the need for a more fundamental knowledge of San Andreas fault dynamics. 相似文献
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Northcutt RG 《Science (New York, N.Y.)》2011,332(6032):926-927
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Transmembrane helical interactions and the assembly of the T cell receptor complex 总被引:23,自引:0,他引:23
Studies of the subunit interactions of the multicomponent T cell antigen receptor (TCR) revealed that specific pairs of chains have the ability to assemble after transfection into fibroblasts. For one such pair, TCR-alpha and CD3-delta, their ability to assemble was encoded by their transmembrane domains. The specificity of this interaction suggests that well-defined helical interactions in the membrane can explain the assembly of some multichain membrane complexes. 相似文献
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NMR characterization of surface interactions in the cytochrome b5-cytochrome c complex 总被引:2,自引:0,他引:2
A M Burch S E Rigby W D Funk R T MacGillivray M R Mauk A G Mauk G R Moore 《Science (New York, N.Y.)》1990,247(4944):831-833
The complex formed in solution by native and chemically modified cytochrome c with cytochrome b5 has been studied by 1H and 13C nuclear magnetic resonance spectroscopy (NMR). Contrary to predictions of recent theoretical analysis, 1H NMR spectroscopy indicates that there is no major movement of cytochrome c residue Phe82 on binding to cytochrome b5. The greater resolution provided by 13C NMR spectroscopy permits detection of small perturbations in the environments of cytochrome c residues Ile75 and Ile85 on binding with cytochrome b5, a result that is in agreement with earlier model-building experiments. As individual cytochrome c lysyl residues are resolved in the 1H NMR spectrum of N-acetimidylated cytochrome c, the interaction of this modified protein with cytochrome b5 has been studied to evaluate the number of cytochrome c lysyl residues involved in binding to cytochrome b5. The results of this experiment indicate that at least six lysyl residues are involved, two more than predicted by static model building, which indicates that cytochrome c and cytochrome b5 form two or more structurally similar 1:1 complexes in solution. 相似文献
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林业生态建设对维护国家生态安全和促进粮食生产都具有重要的意义。平原地区利用自身优势在营造农田防护林中采用林农复合经营模式,将会为农民增收、环境改善发挥重要作用。本文介绍了天津武清区多年来在林农复合经营模式上的方法和有益探索。 相似文献
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Engdahl ER 《Science (New York, N.Y.)》1971,173(4003):1232-1235
Microearthquakes were monitored by a network of seismographs located on Amchitka and nearby islands; the nature of earthquake activity in this region was found to be consistent with the hypothesis of underthrusting of the Aleutian arc by a rigid lithospheric plate. Seismic effects of the nuclear explosion Milrow were small, of short duration, confined to the region immediate to the explosion, and were apparently independent of this geotectonic mechanism. 相似文献