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1.
Kevin Fong 《Earth, Moon, and Planets》2004,94(3-4):169-176
Human space exploration is not considered a strategic priority in the United Kingdom at present. However the UK would benefit from participating in human spaceflight, for both scientific and social reasons. From the point of view of medical science there are many parallels between the physiology of spaceflight and terrestrial disease processes, and studies of the response of astronauts to long-duration spaceflight can therefore help in the development of therapeutic strategies on Earth. On the social side, human spaceflight is an attractive vehicle for stimulating the interest of young people in science and engineering, something that must be of value for an aspiring ‘knowledge-based’ economy. 相似文献
2.
JÜRGEN TITSCHACK CAMPBELL S. NELSON TIM BECK ANDRÉ FREIWALD ULRICH RADTKE 《Sedimentology》2008,55(6):1747-1776
Autochthonous red algal structures known as coralligène de plateau occur in the modern warm‐temperate Mediterranean Sea at water depths from 20 to 120 m, but fossil counterparts are not so well‐known. This study describes, from an uplifted coastal section at Plimiri on the island of Rhodes, a 450 m long by 10 m thick Late Pleistocene red algal reef (Coralligène Facies), interpreted as being a coralligène de plateau, and its associated deposits. The Coralligène Facies, constructed mainly by Lithophyllum and Titanoderma, sits unconformably upon the Plio‐Pleistocene Rhodes Formation and is overlain by a Maerl Facies (2 m), a Mixed Siliciclastic‐Carbonate Facies (0·2 m) and an Aeolian Sand Facies (2·5 m). The three calcareous facies, of Heterozoan character, are correlated with established members in the Lindos Acropolis Formation in the north of the island, while the aeolian facies is assigned to the new Plimiri Aeolianite Formation. The palaeoenvironmental and genetic‐stratigraphic interpretations of these mixed siliciclastic‐carbonate temperate water deposits involved consideration of certain characteristics associated with siliciclastic shelf and tropical carbonate shelf models, such as vertical grain‐size trends and the stratigraphic position of zooxanthellate coral growths. Integration of these results with electron spin resonance dates of bivalve shells indicates that the Coralligène Facies was deposited during Marine Isotope Stage 6 to 5e transgressive event (ca 135 to 120 ka), in water depths of 20 to 50 m, and the overlying Maerl Facies was deposited during regression from Marine Isotope Stage 5e to 5d (ca 120 to 110 ka), at water depths of 25 to 40 m. The capping Aeolian Sand Facies, involving dual terrestrial subunits, is interpreted as having formed during each of the glacial intervals Marine Isotope Stages 4 (71 to 59 ka) and 2 (24 to 12 ka), with soil formation during the subsequent interglacial periods of Marine Isotope Stages 3 and 1, respectively. Accumulation rates of about 0·7 mm year?1 are estimated for the Coralligène Facies and minimum accumulation rates of 0·2 mm year?1 are estimated for the Maerl Facies. The existence of older red algal reefs in the Plimiri region during at least Marine Isotope Stages 7 (245 to 186 ka) and 9 (339 to 303 ka) is inferred from the occurrence of reworked coralligène‐type lithoclasts in the basal part of the section and from the electron spin resonance ages of transported bivalve shells. 相似文献
3.
The trouble with nature: Ambivalence in the lives of urban Australian environmentalists 总被引:1,自引:0,他引:1
The number and range of contests over the social production of nature is growing. Much environmentalist discourse, however, continues to appeal for unequivocal scientific support on clearly demarcated issues of pure, a-social nature. This paper explores the question of how participants in environmental movements view this demarcation in the context of their own lives. After introducing scholarly critique of dualistic ideas of nature and the ambivalence characteristic of environmentalist conceptions of nature, the paper draws upon a qualitative study with environmentalists in the Australian cities of Melbourne, Perth and Hobart. Inquiring into the interplay of discourse of nature and everyday worlds, interviews revealed a complex interdependence of dualistic and non-dualistic understandings of nature. This ecology of ideas was especially evident in spatial imaginaries of nature. Scientific terminology, social disaffection and pessimism were associated with abstract and mutually exclusive conceptions of society and nature. Reflections on personal experience, however, indicated more flexible and hopeful negotiations in everyday liminal spaces offering ‘the best of both worlds’. It is concluded that environmentalist resistance to dismantling of conceptual boundaries between society and nature may often stem not from failure to appreciate socionatural complexity, but from a strongly felt sense that the self can only truly be found in nature. 相似文献
4.
Praxedes Muñoz Javier Sellanes Carina Lange Maritza Palma 《Progress in Oceanography》2007,75(3):586-602
We estimated monthly fluxes of 210Pb in shelf sediments beneath a high productivity area off central-southern Chile (36°S) during 1 year (September 2002-August 2003). Sediment cores were obtained using a multiple corer and were analyzed mainly for 210Pb, total pigments, and macrofauna abundance. The 210Pb inventories and fluxes were estimated for surface sediments (0-5 cm) and bioturbation coefficients were inferred using chlorophyll-a (reactive) profiles. In general, 210Pb content was inversely correlated with phytodetritus fluxes. High photosynthetic pigment contents in surface sediments were consistently associated with lower 210Pb contents. Macrofaunal activity responded to oxygen and organic matter supplies at the sediment surface, generally concentrated in the first centimeters, but particularly so during months of high organic matter fluxes and deficient bottom water oxygen conditions. At this study site, several processes involved in the 210Pb surface distribution make it difficult to accurately estimate ages at the surface. We postulate that the organic fluxes promote changes in the faunal activity, which, in combination with sediment resuspension and water circulation over the shelf, produce seasonal variations in the 210Pb inventories. 相似文献
5.
6.
试论东海陆架盆地的基底构造演化和盆地形成机制 总被引:4,自引:0,他引:4
本文主要根据东海陆架盆地和周边的地质、地球物理资料,分析盆地的基底岩性特征、结构特征。认为东海陆架盆地的基底除元古界片麻岩外,还分布有一定范围的中生界及古生界。基底构造特征是纵向上多层次,横向上不均一,南北有别,东西分带。构造演化上经历了张、合、压、扭等复杂过程。 相似文献
7.
Rony Huys 《Marine Ecology》1991,12(1):1-34
Abstract. Two new genera of Tantulocarida are described from the Ligurian deep sea (Western Mediterranean) off Corsica. Xenalytus scotophilia is referred to the Microdajidae and differs from Microdajus GREVE in thoracopodal segmentation as well as in the presence of coupling spines on thoracopod 6 and longitudinal lamellae on the cephalic shield. Aphotocentor styx is placed in the Deoterthridae and holds an intermediate position between Deoterthron BRADFORD & HEWITT and Boreotantulus HI/YS & BOXSHALL. Some aspects of cephalon internal structure are described for the first time and give a possible explanation for the mechanism of stylet protrusion. The external structures of the oral disc are described using SEM. The discovery of well-developed muscles in the trunk and thoracopods is discussed in the light of the benthic phase the tantulus passes through. The boundary between the thorax and abdomen in the tantulus is reinterpreted, corroborating the 5–7-5 bodyplan of the hypothetical urmaxillopodan as found in the Upper Cambrian Skaracarida and possibly also Dala peilertae MOLLER. Some aspects related to dispersal, infection, and feeding are reinterpreted or approached from a different perspective. SEM of Microdajus langi GREVE gives evidence that the tantuli hatch via a conspicuous slit located at the posterior end of the female trunk sac. A worldwide key to the tantulocaridan families and genera is given, and distributional records are compiled. It is suggested that Tantulocarida might be common representatives of the temporary meiobenthos and that their present species number represents only the tip of the iceberg. 相似文献
8.
9.
1 .IntroductionTheappraisalofagooddesignforaverylargefloatingstructure(VLFS)thatwillserveinaspeci fiedoceanarearequiresthatthestructuralsystembeeconomicallydesigned ,therequirementsforitsfunctionbesatisfiedandthestructurekeepsstableinitswholeserviceperio… 相似文献
10.
Samples of O isotopic tracer were mlleMed at Sections P3,P25,PcM-t/2-E and PCM-1/2.w in both the Fast China Sea and the area to the east of the Ryūkyū-gunto during October-November,1991.Analytical results of the δ18O are as follows: (1) In the Kuroshio area,the δ18O isolines are almost parallel to the 200 m isobath.The value of δ18O is negative and reaches minimum mt the main axis of the Kuroshio,and increases on both sides.(2) In the Taiwan Warm Current (TWC) area there is a high δ18O tongue extending to the northeast.(3) In the area near the coast,the distribution of δ18O isoline shows that the Changjiang River runoff diffuses seaward and the land-ocean isotopic effect from the nearshore to the offshore.(4) The values of δ18O are from -1.0×10-3 to -0.5×10-3 in the shelf.(5) There is a low mre of δ18O value(<-1.6×10-3) at the 600 m layer in the Kuroshio area,which is quite in accord with the existence of a low salinity mre (S G 34.30) between the 600 and 800 m layers in the same area.Finally,the mrrelations of the δ18O with the salinity and temperature,the upwelling and so on are discussed. 相似文献