Galaxy evolution in clusters     

E. Ellingson 《Astrophysics and Space Science》2003,285(1):9-18

The galaxy populations in present-day clusters are distinctly different from those of the field, indicating that environment plays a strong role in galaxy evolution. This review discusses some of the recent observations of moderate to high redshift clusters. A consistent picture of galaxy evolution in clusters appears to be emerging, which includes a population of galaxies which formed early in the cluster history, as well as field galaxies which have had their star formation truncated upon falling into the cluster potential. Galaxy interactions probably play an important role in exhausting star formation in some of these galaxies. However, there is significant variation in the populations of different cluster samples, with substantial evidence that some galaxies have their star formation terminated more gradually. This suggests that different mechanisms may dominate in different clusters, perhaps because of the recent merging history of the clusters. We also present a recent analysis of population gradients in clusters which suggests that the observed evolution in cluster populations is consistent with a scenario where changing infall rates drive the fraction of star forming galaxies in clusters, rather than a changing physical mechanism within the cluster. Thus, galaxy populations may provide a fundamental measure of the growth of large scale structure. This revised version was published online in July 2006 with corrections to the Cover Date.  相似文献   

BOOK REVIEWS     

《The Professional geographer》1983,35(2):230-260

Book Reviewed in this article: Rabat: Urban Apartheid in Morocco . Janet Abu -Lughod . Marketplaces in a Developing Country: The Case of Western Nigeria . Isaac Ayinde Adalemo . Farming Development and Space: A World Agricultural Geography . Bernd Andreae . Section and Party: A Political Geography of American Presidential Elections, from Andrew Jackson to Ronald Reagan . J. Clark Archer and Peter J. Taylor . Women and Space: Ground Rules and Social Maps . Shirley Ardener , ed. European Progress in Spatial Analysis . R. J. Bennett , ed. The Origins of Academic Geography in the United States . Brian W. Blouet Geographic Perspectives on Global Problems . Ronald Reed Boyce . Seasonal Dimensions to Rural Poverty . Robert Chambers , Richard Longhurst and Arnold Pacey eds. The New Nationalism and the Use of Common Spaces: Issues in Marine Pollution and the Exploitation of Antarctica . Jonathan I. Charney , ed. Communications Tomorrow: The Coming of the Information Society . Edward Cornish , ed. The Design of Suburbia . Arthur Edwards . Explorer on the Northern Plains: Lieutenant Gouverneur K. Warren's Preliminary Report of Explorations in Nebraska and Dakota in the Years 1855–56–57. With an Introduction by Frank N. Schubert . The Changing Climate: Responses of the Natural Flora and Fauna . Michael J. Ford . Essentials of Physical Geography . Robert E. Gabler , Robert J. Sager , Sheila Brazier , and Daniel L. Wise. The Road to Jaramillo . William Glen . Valued Environments . John R. Gold and Jacquelin Burgess , eds. Proximity and Preference: Problems in the Multidimensional Analysis of Large Data Sets . Reginald G. Golledge and John N. Rayner , eds. A Search for Common Ground . Peter Gould and Gunnar Olsson , eds. Geography: Its History and Concepts . Arild Holt -Jensen . A Population Geography . Huw R. Jones . The Human Mosaic: A Thematic Introduction to Cultural Geography, 3rd ed. Terry G. Jordan and Lester Rowntree . Urban Social Geography: An Introduction . Paul Knox . The Anatomy of Job Loss: The How, Why and Where of Employment Decline . Doreen Massey and Richard Meegan . The Information Society as Post-Industial Society . Yoneji Masuda . Map Librarianship, 2nd ed. Harold Nichols . India: Cultural Patterns and Processes . Allen G. Noble and Ashok K. Dutt , eds. The God that Limps: Science and Technology in the Eighties . Colin Norman . Geography: An Introductory Perspective . Robert E. Norris , Keith D. Harries and John D. Vitek . The Politics of Technology Assessment . David M. O'Brien and Donald A. Marchand . Ethnic Segregation in Cities . Ceri Peach , Vaughan Robinson and Susan Smith , eds. Churches and Church Membership in the United States, 1980 . Bernard Quinn , Herman Anderson , Martin Bradley , Paul Goetting and Peggy Shriver . Energy in Australia: Politics and Economics . Hugh Saddler . Development from Above or Below? The Dialectics of Regional Planning in Developing Countries . Walter B. Stóuhr and D. R. Fraser Taylor , eds. Human Impact on the Ecosystem . Joy Tivy and Greg O'Hare . Plants and People: Vegetation Change in North America . Thomas R. Vale . The Mapmakers: The Story of the Great Pioneers in Cartography from Antiquity to the Space Age . John Noble Wilford .  相似文献   

The long-term effects of crude oil on microbial processes in subarctic marine sediments     

Robert P. Griffiths  Bruce A. Caldwell  William A. Broich  Richard Y. Morita 《Estuarine, Coastal and Shelf Science》1982,15(2):183-198

Subarctic marine sediments were exposed to fresh and ‘weathered’ crude oil from Cook Inlet, Alaska. The crude oil was thoroughly mixed with the sediment at various concentrations and some of the oil-sediment mixtures were placed on top of unamended sediments. Both sediments with added oil and those overlain by oiled sediments were investigated. These sediments were placed either in trays or aquaria. The trays were incubated in situ near the site from which the sediments were originally collected. The aquaria were maintained at simulated in situ conditions by maintaining a continuous flow of fresh seawater through them. The sediments were exposed to crude oil for periods up to 1.5 years. Sediments exposed to 50‰ fresh crude oil showed significant decreases in nitrogen fixation and denitrification rates and redox potentials. Also observed were increases in CO₂ production rates and methane concentrations. These same changes were observed in sediments exposed to 1‰. When ‘weathered’ crude oil was added to the sediments, the same changes were observed except there was no reduction in nitrogen fixation activity. In most cases, the observed effects were less marked when the sediments were amended with ‘weathered’ crude oil than with the same concentration of fresh crude oil. Untreated sediments that were overlain with treated sediments showed the same changes as those sediments that were thoroughly mixed with crude oil. The presence of fresh crude oil at 50‰ essentially eliminated burrowing activity of the benthic infauna. Under these conditions, there was an accumulation of detritus particles on the oiled sediments that was not present in the untreated controls.  相似文献   

Restoration of turbulence profile from scintillation indices   总被引：1，自引：0，他引：1  

A. Tokovinin  V. Kornilov  N. Shatsky  O. Voziakova 《Monthly notices of the Royal Astronomical Society》2003,343(3):891-899

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Non-adiabatic effects in the solar p-mode oscillations     

Shao-lan Bi  Ru-feng Li 《Chinese Astronomy and Astrophysics》1997,21(4):474-480

Non-adiabatic effects associated with radiative loss and convective transfer add small imaginary parts to solar p-mode eigenfrequencies. An asymptotic approximation is developed to study the non-adiabatic effects. For the outermost layer where the approximation is not valid, an exact solution of the equation of non-adiabatic oscillation which results in an cigenfunction equation, is used. The inclusion of the non-adiabatic effects reduces the discrepancy between the theory and observations particularly for frequencies above 3.1 mHz.  相似文献   

EFFECTS OF SLOPING BOTTOM ON THE DEEPCROSS-EQUATORIAL BOUNDARY CURRENT     

吴德星  吕红民  郭群  卢镇 《中国海洋湖沼学报》1997,15(1):65-69

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成都城市热岛效应研究     

杨柏生 《成都信息工程学院学报》1988,(2)

木文通过成都城市气温的水平测量及多点低层探空测量的资料,分析了在不同条件下的热岛强度、中心位置及垂直方向上的伸展高度等变化规律、在考虑到热岛强度非周期性变化时,建立了适用于成都城市的热岛强度△Tμ-γ的回归计算公式。  相似文献   

Oscillations of levels and cool phases of the Laurentian Great Lakes caused by inflows from glacial Lakes Agassiz and Barlow-Ojibway   总被引：1，自引：0，他引：1  

C. F. M. Lewis  T. W. Anderson 《Journal of Paleolimnology》1989,2(2):99-146

Two distinct episodes of increased water flux imposed on the Great Lakes system by discharge from upstream proglacial lakes during the period from about 11.5 to 8 ka resulted in expanded outflows, raised lake levels and associated climate changes. The interpretation of these major hydrological and climatic effects, previously unrecognized, is mainly based on the evidence of former shorelines, radiocarbon-dated shallow-water sediment sequences, paleohydraulic estimates of discharge, and pollen diagrams of vegetation change within the basins of the present Lakes Superior, Michigan, Huron, Erie and Nipissing. The concept of inflow from glacial Lake Agassiz adjacent to the retreating Laurentide Ice Sheet about 11–10 and 9.5–8.5 ka is generally supported, with inflow possibly augmented during the second period by backflooding of discharge from glacial Lake Barlow-Ojibway.Although greater dating control is needed, six distinct phases can be recognized which characterize the hydrological history of the Upper Great Lakes from about 12 to 5 ka; 1) an early ice-dammed Kirkfield phase until 11.0 ka which drained directly to Ontario basin; 2) an ice-dammed Main Algonquin phase (11.0–10.5 ka) of relatively colder surface temperature with an associated climate reversal caused by greater water flux from glacial Lake Agassiz; 3) a short Post Algonquin phase (about 10.5–10.1 ka) encompassing ice retreat and drawdown of Lake Algonquin; 4) an Ottawa-Marquette low phase (about 10.1–9.6 ka) characterized by drainage via the then isostatically depressed Mattawa-Ottawa Valley and by reduction in Agassiz inflow by the Marquette glacial advance in Superior basin; 5) a Mattawa phase of high and variable levels (about 9.6–8.3 ka) which induced a second climatic cooling in the Upper Great Lakes area. Lakes of the Mattawa phase were supported by large inflows from both Lakes Agassiz and Barlow-Ojibway and were controlled by hydraulic resistance at a common outlet — the Rankin Constriction in Ottawa Valley — with an estimated base-flow discharge in the order of 200000 m³s^–1. 6) Lakes of the Nipissing phase (about 8.3–4.7 ka) existed below the base elevation of the previous Lake Mattawa, were nourished by local precipitation and runoff only, and drained by the classic North Bay outlet to Ottawa Valley.Geological Survey of Canada Contribution 42488.This is the twelfth of a series of papers to be published by this journal that was presented in the paleolimnology sessions organized by R. B. Davis and H. Löffler for the XIIth Congress of the International Union for Quaternary Research (INQUA), which took place in Ottawa, Canada in August 1987. Dr. Davis is serving as guest editor of this series.  相似文献   

Scale effects in fluvial sediment-associated chemical data     

E. D. Ongley 《水文研究》1987,1(2):171-179

Assessment of man's impact on fluvial systems frequently involves extrapolation in time and space from data collected as part of a water quality network. Extrapolation represents information transfer and is used for scenario building and risk assessment. Transfer functions for non-conservative quality variables are poorly understood. Metals, phosphorus, and organic contaminants, which are preferentially transported in association with suspended sediment, are especially susceptible to extrapolation errors. Information loss, which is inherent in extrapolation procedures, is characterized for sediment-associated substances by examining the assumptions and limitations of the sediment delivery ratio. A practical demonstration of scale effects and interpretive difficulties is provided using data from the Bow River, Alberta. Guidelines for data assessment and extrapolation are summarized for temporal effects and for three different spatial scales.  相似文献   

A Theoretical Investigation of Source, Path and Site Effects During the 1986 Kalamata Earthquake (Greece)     

Jean-Christophe Gariel  Pierre-Yves Bard  Kyriazis Pitilakis 《Geophysical Journal International》1991,104(1):165-178

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