Anomalous Fe II spectral effects and high H I Lyα temperature in gas blobs near η Carinae     

S. Johansson  V. S. Letokhov 《Astronomy Letters》2004,30(1):58-63

We consider the origin of the anomalously high intensity of the ultraviolet Fe II λλ2507/2509 Å lines observed with high spatial and spectral resolutions from gas blobs (GBs) near η Carinae. This rare effect in stellar spectra is attributable to a combination of several factors: (1) the high hydrogen density(>10⁸ cm^?3) that ensures the blockingof the Lyman continuum by GBs and, accordingly, the formation of a cold H I region with completely ionized Fe atoms; (2) the small distance between the GBs and the central star that ensures a high (>8000–10000 K) Lyα H spectral temperature, which photoexcites Fe II selectively; and (3) the population of Fe II levels and, accordingly, the opening of a stimulated emission channel, which together with spontaneous transitions creates a radiative cycle where a single Fe II ion can multiply absorb Lyα emission.  相似文献   

Reconstructing floodplain sedimentation rates from heavy metal profiles by inverse modelling     

Hans Middelkoop 《水文研究》2002,16(1):47-64

The embanked floodplains of the lower River Rhine in the Netherlands contain large amounts of heavy metals, which is a result of many years deposition of contaminated overbank sediments. Depending on local sedimentation rates and changing pollution trends in the past, the metal pollution varies greatly between different floodplain sections as well as vertically within the floodplain soil profiles. Maximum metal concentrations in floodplain soils vary from 30 to 130 mg/kg for Cu, from 70 to 490 mg/kg for Pb and from 170 to 1450 mg/kg for Zn. In the present study these metals were used as a tracer to reconstruct sedimentation rates at 28 sites on the lower River Rhine floodplains. The temporal trend in pollution of the lower River Rhine over the past 150 years was reconstructed on the basis of metal concentrations in sediments from small ponds within the floodplain area. Using a one‐dimensional sedimentation model, average sedimentation rates over the past century were determined using an inverse modelling calibration procedure. The advantage of this method is that it uses information over an entire profile, it requires only a limited number of samples, it accounts for post‐depositional redistribution of the metals, and it provides quantitative estimates of the precision of the sedimentation rates obtained. Estimated sedimentation rates vary between about 0·2 mm/year and 15 mm/year. The lowest metal concentrations are found in the distal parts of floodplain sections with low flooding frequencies and where average sedimentation rates have been less than about 5 mm/year. The largest metal accumulations occur in low‐lying floodplain sections where average sedimentation rates have been more than 10 mm/year. Copyright © 2002 John Wiley & Sons, Ltd.  相似文献   

Der Basaltstock des Weilberges im Siebengebirge     

Hans Cloos 《International Journal of Earth Sciences》1948,35(1):33-35

Ohne Zusammenfassung  相似文献   

Preface     

Walter Fernandez  Hans J. Haubold 《Earth, Moon, and Planets》1993,63(2):iii-iii

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Thetys subduction and continental collision imaged by magnetic and gravity modeling     

Vahid Teknik  Abdolreza Ghods  Hans Thybo  Irina M. Artemieva 《《地质学报》英文版》2018,92(Z1):61-62

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The application of a groundwater/surface-water model to test the vulnerability of Bracciano Lake (near Rome,Italy) to climatic and water-use stresses     

Sara Taviani  Hans Jørgen Henriksen 《Hydrogeology Journal》2015,23(7):1481-1498

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Drought variability in eastern Mongolian Plateau and its linkages to the large-scale climate forcing   总被引：1，自引：0，他引：1  

Guang Bao  Yu Liu  Na Liu  Hans W. Linderholm 《Climate Dynamics》2015,44(3-4):717-733

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The role of intracontinental deformation in supercontinent assembly: insights from the Ribeira Belt,Southeastern Brazil (Neoproterozoic West Gondwana)   总被引：1，自引：0，他引：1       下载免费PDF全文

Vinícius T. Meira  Antonio García‐Casco  Caetano Juliani  Renato P. Almeida  Johann Hans D. Schorscher 《地学学报》2015,27(3):206-217

In this study, we challenge the multiple collision model for the tectonic evolution of the Neoproterozoic Ribeira Belt in Southeastern Brazil. New U–Pb SHRIMP data reveal Palaeoproterozoic (2153 ± 15 Ma) and Cryogenian (783 ± 6 and 768 ± 8 Ma) granitic rocks in the Embu Domain, and detrital zircon data of metasedimentary units from the Embu and Costeiro domains suggest a coherent tectonic evolution for the whole Ribeira Belt. Rather than by multiple collisions, these data are best explained by a simpler tectonic model involving continent (craton)‐volcanic arc collisions in the Dom Feliciano and Brasilia belts that led to intracontinental crustal thickening of the adjacent thinned hinterland (Ribeira Belt) at ~640–610 Ma, followed by widespread post‐collisional magmatism and rift‐related sedimentation at ~600–540 Ma. We suggest that intracontinental orogeny is a relevant process during supercontinent assembly, as illustrated here by the evolution of significant parts of the Brasiliano orogen.  相似文献   

Der geologische Lehrstuhl an der Universität Neuenburg in der Schweiz     

Hans Cloos 《International Journal of Earth Sciences》1941,32(3):389-393

Ohne Zusammenfassung  相似文献   

Tektonische Probleme am Nordrand des Harzes     

Hans Cloos 《International Journal of Earth Sciences》1916,7(7-8):314-329

Ohne ZusammenfassungVgl.Cloos, Eine neue Störungsform, (8).  相似文献