The XMM-Newton Serendipitous Sky Survey     

Prof.  Mike Watson 《Astronomy& Geophysics》2007,48(5):5.30-5.30

Mike Watson heralds the 2XMM catalogue, a valuable new X-ray astronomy resource compiled from XMM-Newton observations.  相似文献   

Shields for the starship Enterprise     

Ruth Bamford  Robert Bingham  Mike Hapgood 《Astronomy& Geophysics》2007,48(6):6.18-6.23

Ruth Bamford, Robert Bingham and Mike Hapgood discuss the physics behind shielding spacecraft from solar and cosmic radiation with mini-magnetospheres.  相似文献   

Quantifying the relationship between structural deformation and the morphology of submarine channels on the Niger Delta continental slope     

W. Hamish Mitchell  Alexander C. Whittaker  Mike Mayall  Lidia Lonergan  Marco Pizzi 《Basin Research》2021,33(1):186-209

The processes and deposits of deep‐water submarine channels are known to be influenced by a wide variety of controlling factors, both allocyclic and autocyclic. However, unlike their fluvial counterparts whose dynamics are well‐studied, the factors that control the long‐term behaviour of submarine channels, particularly on slopes undergoing active deformation, remain poorly understood. We combine seismic techniques with concepts from landscape dynamics to investigate quantitatively how the growth of gravitational‐collapse structures at or near the seabed in the Niger Delta have influenced the morphology of submarine channels along their length from the shelf edge to their deep‐water counterpart. From a three dimensional (3D), time‐migrated seismic‐reflection volume, which extends over 120 km from the shelf edge to the base of slope, we mapped the present‐day geomorphic expression of two submarine channels and active structures at the seabed, and created a Digital Elevation Model (DEM). A second geomorphic surface and DEM raster—interpreted to closer approximate the most recent active channel geometries—were created through removing the thickness of hemipelagic drape across the study area. The DEM rasters were used to extract the longitudinal profiles of channel systems with seabed expression, and we evaluate the evolution of channel widths, depths and slopes at fixed intervals downslope as the channels interact with growing structures. Results show that the channel long profiles have a relatively linear form with localized steepening associated with seabed structures. We demonstrate that channel morphologies and their constituent architectural elements are sensitive to active seafloor deformation, and we use the geomorphic data to infer a likely distribution of bed shear stresses and flow velocities from the shelf edge to deep water. Our results give new insights into the erosional dynamics of submarine channels, allow us to quantify the extent to which submarine channels can keep pace with growing structures, and help us to constrain the delivery and distribution of sediment to deep‐water settings.  相似文献   

Sedimentary environments and facies,H. G. Reading (Ed.), Blackwells, 1978 (Reprinted 1979). No. of pages: 557     

Mike Leeder 《地球表面变化过程与地形》1981,6(1):98-98

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The 2012 Olympic Learning Legacy Agenda – the intentionalities of mobility for a new London model     

Susan Moore  Mike Raco  Ben Clifford 《Urban geography》2018,39(2):214-235

This paper investigates the emergence of a Learning Legacy Agenda (LLA) in the wake of the London 2012 Olympic Games as a governmental tool for the dissemination of urban development and infrastructure project delivery best practice. Focusing on the inception, coordination and implementation of the LLA we outline the intentionalities of mobility that underpin its formation and appropriation and suggest how this points to the emergence of a new “London model” of development and governance. Three intentionalities of knowledge capture, public duty and extra-local salience are unpacked to demonstrate the range of ways in which the bureaucratically initiated LLA banner has been used by various development actors and organisations to validate their existing practices. The case study of the LLA as an institutionalised governance apparatus is used to analyse the impact of specific forms of social relations on the ways in which “models” are produced, what their content consists of, how dominant agendas and narratives co-evolve with the priorities of an assemblage of actors and the processes of selective abstraction used to curate particular messages and forms of fixed and potentially mobile knowledge, yet dubious claims of “learning”.  相似文献   

Anorthositic lunar regolith breccia Dhofar 1769—Clear indications for repeated mixing of impact melt lithologies     

Addi Bischoff  Mike Komnik  Jakob Storz  Jasper Berndt 《Meteoritics & planetary science》2023,58(9):1260-1273

The lunar regolith breccia Dhofar 1769, which was found in 2012 as a single 125 g piece in the Zufar desert area of Oman, contains a relatively large, dark-colored impact melt breccia embedded in a fine-grained clastic matrix. The internal texture of the fragment indicates the repeated melt breccia formation on the lunar surface, their repeated brecciation, and mixing in second, third, and fourth generations of brecciated rock types. The chemical and mineralogical data reveal the incorporation of a feldspar-rich subophitic crystalline melt within a feldspar-rich microporphyritic crystalline melt breccia. This lithic paragenesis itself is embedded within a mafic, crystalline melt breccia. The entire breccia with the three different impact melts has been finally incorporated into the whole rock breccia. The three impact melts are mixtures of different source rocks and impact projectiles, based on the obtained minor and trace element compositions (in particular of Ni and the rare earth elements [REE]) of the impact melt lithologies. For all processes of impact melt formation, additional steps of their brecciation and re-lithification require a minimum number of seven impact processes.  相似文献   

Wetland Accretion Rate Model of Ecosystem Resilience (WARMER) and Its Application to Habitat Sustainability for Endangered Species in the San Francisco Estuary     

Kathleen M. Swanson  Judith Z. Drexler  David H. Schoellhamer  Karen M. Thorne  Mike L. Casazza  Cory T. Overton  John C. Callaway  John Y. Takekawa 《Estuaries and Coasts》2014,37(2):476-492

Salt marsh faunas are constrained by specific habitat requirements for marsh elevation relative to sea level and tidal range. As sea level rises, changes in relative elevation of the marsh plain will have differing impacts on the availability of habitat for marsh obligate species. The Wetland Accretion Rate Model for Ecosystem Resilience (WARMER) is a 1-D model of elevation that incorporates both biological and physical processes of vertical marsh accretion. Here, we use WARMER to evaluate changes in marsh surface elevation and the impact of these elevation changes on marsh habitat for specific species of concern. Model results were compared to elevation-based habitat criteria developed for marsh vegetation, the endangered California clapper rail (Rallus longirostris obsoletus), and the endangered salt marsh harvest mouse (Reithrodontomys raviventris) to determine the response of marsh habitat for each species to predicted >1-m sea-level rise by 2100. Feedback between vertical accretion mechanisms and elevation reduced the effect of initial elevation in the modeled scenarios. Elevation decreased nonlinearly with larger changes in elevation during the latter half of the century when the rate of sea-level rise increased. Model scenarios indicated that changes in elevation will degrade habitat quality within salt marshes in the San Francisco Estuary, and degradation will accelerate in the latter half of the century as the rate of sea-level rise accelerates. A sensitivity analysis of the model results showed that inorganic sediment accumulation and the rate of sea-level rise had the greatest influence over salt marsh sustainability.  相似文献   

Ethnohistoric and Geoarchaeological Landscape Chronology at Kawaihae,Leeward Hawai‘i Island     

Mike T. Carson 《Geoarchaeology》2012,27(5):385-409

The royal court of the Kamehameha Dynasty in Kawaihae, Hawai‘i Island, presents an unequalled opportunity to examine the ethnohistoric rendering of a cultural landscape, in comparison to the geoarchaeological record of physical transformation of this same landscape. Beneath the surface, earlier occupation layers predate the historic royal precinct of the A.D. 1790s through 1820s. Drawing on results of 19 controlled excavations, point‐specific cultural activities are situated within the last several centuries of natural terrain formation, beginning A.D. 1200–1400 and ending A.D. 1830–present. Geoarchaeological excavations provide the means to place the stratified cultural deposits, occupational horizons, and activity areas in the context of depositional history, environmental transformation, and changing social circumstances in a continuous sequence. The material‐based geoarchaeological landscape chronology and the ethnohistorically defined cultural landscape are combined for a more holistic view than either one could provide independently.  相似文献   

Dietary niche separation of three Late Pleistocene bear species from Vancouver Island,on the Pacific Northwest Coast of North America     

Cara Kubiak  Vaughan Grimes  Geert Van Biesen  Grant Keddie  Mike Buckley  Reba Macdonald  M. P. Richards 《第四纪科学杂志》2023,38(1):8-20

Competition between taxa related to climate changes has been proposed as a possible factor in Pleistocene megafaunal extinctions, and here we present isotope evidence of the diets of three co-existing bear species [black bear (Ursus americanus), brown bear (Ursus arctos), and the now extinct short-faced bear (Arctodus simus)] from a locale in western North America dating to the Late (Terminal) Pleistocene (~14.5–11.7 ka). The three bear species were found at several sites on Vancouver Island, on the western coast of Canada. To examine the chronological overlap and niche partitioning between these species of bear, we used direct radiocarbon dating, stable isotope analysis and ZooMS proteomic identification methods. Here we present new radiocarbon evidence from Terminal Pleistocene U. americanus, U. arctos and A. simus from several sites on the island, along with both bulk collagen and compound-specific isotope data for these species. Radiocarbon dates confirm the chronological overlap of Arctodus and both Ursus species in the montane regions of the island at the end of the Pleistocene. Stable isotope data reveal niche differentiation between these species, with U. americanus occupying a distinctly lower trophic position than the other two taxa.  相似文献   

Correlation of environmental and cultural chronology in New Caledonia     

Mike T. Carson 《Geoarchaeology》2008,23(5):695-714

A case study in New Caledonia explores the changes in the natural and cultural setting at the end of the Lapita period in the first millennium B.C. After the mid‐Holocene highstand, sea level fell about 1.5 m, thereby enlarging coastal plains, altering previous mangrove and marshy settings, and transforming nearshore marine environments. Many of these changes occurred gradually over several centuries, but the termination of finely decorated Lapita pottery coincided with the first signs of loss of coastal habitat optimal for marine‐based horticulturalists in the first millennium B.C. Organized village compounds and extensively cultivated landscapes emerged much later, in the first millennium A.D. The results suggest that, although the Lapita phenomenon represents the founding ancestry of Oceanic societies, it also represents the end of an era and way of life that eventually could not be maintained in a changing world. © 2008 Wiley Periodicals, Inc.  相似文献