Spectral discrimination between Soviet explosions and earthquakes using short-period array data     

Steven R. Taylor  Peter D. Marshall 《Geophysical Journal International》1991,106(1):265-273

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Theory of protoplanetary disks     

Steven P. Ruden 《Astrophysics and Space Science》1995,223(1-2):57-68

The evolution of protoplanetary disks around young stars is briefly reviewed. The most important physical mechanisms that drive the mass accretion are gravitational, magnetic, and thermal convective instabilities. These mechanisms are dominant in different regions of the disk and at different evolutionary epochs.  相似文献   

Analysis of elastic symmetry from velocity measurements with application to dunite and bronzitite     

Steven Harder 《Geophysical Journal International》1988,94(3):469-477

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Quaternary palaeoceanographic changes in the northern South China Sea (ODP Site 1146): radiolarian evidence     

Rujian Wang  Steven Clemens  Baoqi Huang  Muhong Chen 《第四纪科学杂志》2003,18(8):745-756

The abundance and accumulation rates of siliceous microfossils in the northern South China Sea, including radiolarians, diatoms and sponge spicules, increased during most glacial intervals within the past 1100 kyr. Similar trends are observed in the index of thermocline surface radiolarians (TSR), diatom accumulation rates (DAR), charcoal accumulation rates (CAR) and the abundance of radiolarian species Cycladophora davisiana davisiana. Decreasing sea‐surface temperature accompanied by increased seasonality since 900 ka is indicated by a decline in the tropical radiolarian assemblage, including Tetrapyle octacantha and Octopyle stenozona, and by an increase in the subtropical assemblage, including Pterocorys zancleus, Peromelissa phalacra and Ommatartuts tetrathalamus tetrathalamus. Rapid increases at about 800 to 700 ka of siliceous microfossils, charcoal, subsurface and intermediate radiolarians, as well as the TSR index and the DAR, imply a fundamental shift in climate and a shoaling thermocline. Although these fundamental changes in the silicious fauna and flora of the South China Sea take place within the context of a developing 100‐kyr cycle, they do not change in step with changing sea‐level as indicated by marine δ¹⁸O. This is most clearly illustrated by the step‐like increase in silica accumulation (radiolaria, diatoms and sponge spicules) at 680 ka. Rather, these fundamental changes probably reflect intensified surface productivity associated with enhanced East Asian winter‐monsoon circulation. Copyright © 2003 John Wiley & Sons, Ltd.  相似文献   

On the disappearance of a small sunspot group     

Steven G. Wallenhorst  Kenneth P. Topka 《Solar physics》1982,81(1):33-46

The small sunspot group associated with Hale active region 17694 was observed jointly by the Mount Wilson and the Big Bear Solar Observatories, through the time of sunspot disappearance. The magnetic flux from the region was seen to decrease by about 10% per day during the observing interval. This was accompanied by fragmentation of the dominant spot as a supergranule network formed. No evidence for spreading or diffusion of the active region field was found.  相似文献   

Simulation of Salt-Water Interface Motion   总被引：2，自引：0，他引：2  

James W. Mercer  Steven P. Larson  Charles R. Faust 《Ground water》1980,18(4):374-385

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Lightning,auroras, nocturnal light,and related luminous phenomena: William R. Corliss. Sourcebook Project,Glen Arm,Md., 1982. 242 pp., $11.95     

Steven Soter 《Icarus》1983,56(3):615-616

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Movement of Volatile Organics Through a Fractured Rock Aquifer     

Steven E.Spayd 《Ground water》1985,23(4):496-502

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The utility of regional Chinese seismograms for source and path studies in central Asia     

Howard J. Patton  Steven R. Taylor  David B. Harris  Joseph M. Mills 《Geophysical Journal International》1985,81(2):469-478

Summary. Broadband seismograms from the National Seismic Network of the People's Republic of China (PRC) have recently become available through a data exchange programme between NOAA and the State Seismological Bureau of the PRC. In this study, regional surface waves recorded at the Urumchi station located about 700 km north of the Tibetan Plateau in the Sinkiang Province are used to study East Kazakh explosions and wave propagation in central Asia. The data consist of broadband (flat to displacement between 0.1 and 10 Hz), photographic records from an SK Kirnos galvanometric system. Simultaneous inversion of Rayleigh wave phase and group velocities for the path from East Kazakh through the Dzhungarian Basin yields a crustal model dominated by the presence of very low velocities and a strong positive velocity gradient above 15 km depth. Velocities below 15 km depth are not significantly different from other continental structures underlain by Palaeozoic or Precambrian basement. Seismic moments were estimated for seven East Kazakh explosions using models of explosion sources with associated tectonic strain release. The largest explosion studied occurred on 1980 September 14 and had an m_b of 6.2 and a seismic moment of 2.7 × 10²³ dyn cm. The observed amplitude spectra of Rayleigh waves are richer in high frequencies than spectra calculated from our models. This could be caused by a path effect involving seismic wave focusing by the Dzhungarian Basin, although source medium effects cannot be ruled out.  相似文献   

International Pellet Watch: Global monitoring of persistent organic pollutants (POPs) in coastal waters. 1. Initial phase data on PCBs, DDTs, and HCHs   总被引：1，自引：0，他引：1  

Yuko Ogata  Kaoruko Mizukawa  Satoru Iwasa  Yukie Mato  Keiji Okuda  Michio Murakami  Ruchaya Booyatumanondo  Le Quang Dung  Carlos Miguez  Charles Moore  Steven Weerts  Erick Burres  Michael Van Velkenburg  Richard C. Lang  Brenda Danner  Richard C. Thompson 《Marine pollution bulletin》2009,58(10):1437-1446

Samples of polyethylene pellets were collected at 30 beaches from 17 countries and analyzed for organochlorine compounds. PCB concentrations in the pellets were highest on US coasts, followed by western Europe and Japan, and were lower in tropical Asia, southern Africa and Australia. This spatial pattern reflected regional differences in the usage of PCBs and was positively correlated with data from Mussel Watch, another monitoring approach. DDTs showed high concentrations on the US west coast and in Vietnam. In Vietnam, DDT was predominant over its metabolites (DDE and DDD), suggesting the principal source may be current usage of the pesticide for malaria control. High concentrations of pesticide HCHs were detected in the pellets from southern Africa, suggesting current usage of the pesticides in southern Africa. This study demonstrates the utility and feasibility of the International Pellet Watch approach to monitor POPs at a global scale.  相似文献