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Stability of the Larsen B ice shelf on the Antarctic Peninsula during the Holocene epoch 总被引:1,自引:0,他引:1
Domack E Duran D Leventer A Ishman S Doane S McCallum S Amblas D Ring J Gilbert R Prentice M 《Nature》2005,436(7051):681-685
The stability of the Antarctic ice shelves in a warming climate has long been discussed, and the recent collapse of a significant part, over 12,500 km2 in area, of the Larsen ice shelf off the Antarctic Peninsula has led to a refocus toward the implications of ice shelf decay for the stability of Antarctica's grounded ice. Some smaller Antarctic ice shelves have undergone periodic growth and decay over the past 11,000 yr (refs 7-11), but these ice shelves are at the climatic limit of ice shelf viability and are therefore expected to respond rapidly to natural climate variability at century to millennial scales. Here we use records of diatoms, detrital material and geochemical parameters from six marine sediment cores in the vicinity of the Larsen ice shelf to demonstrate that the recent collapse of the Larsen B ice shelf is unprecedented during the Holocene. We infer from our oxygen isotope measurements in planktonic foraminifera that the Larsen B ice shelf has been thinning throughout the Holocene, and we suggest that the recent prolonged period of warming in the Antarctic Peninsula region, in combination with the long-term thinning, has led to collapse of the ice shelf. 相似文献
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The stress-activated protein kinase pathways 总被引:29,自引:0,他引:29
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Slip zone and energetics of a large earthquake from the Taiwan Chelungpu-fault Drilling Project 总被引:6,自引:0,他引:6
Ma KF Tanaka H Song SR Wang CY Hung JH Tsai YB Mori J Song YF Yeh EC Soh W Sone H Kuo LW Wu HY 《Nature》2006,444(7118):473-476
Determining the seismic fracture energy during an earthquake and understanding the associated creation and development of a fault zone requires a combination of both seismological and geological field data. The actual thickness of the zone that slips during the rupture of a large earthquake is not known and is a key seismological parameter in understanding energy dissipation, rupture processes and seismic efficiency. The 1999 magnitude-7.7 earthquake in Chi-Chi, Taiwan, produced large slip (8 to 10 metres) at or near the surface, which is accessible to borehole drilling and provides a rare opportunity to sample a fault that had large slip in a recent earthquake. Here we present the retrieved cores from the Taiwan Chelungpu-fault Drilling Project and identify the main slip zone associated with the Chi-Chi earthquake. The surface fracture energy estimated from grain sizes in the gouge zone of the fault sample was directly compared to the seismic fracture energy determined from near-field seismic data. From the comparison, the contribution of gouge surface energy to the earthquake breakdown work is quantified to be 6 per cent. 相似文献
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Star B Nederbragt AJ Jentoft S Grimholt U Malmstrøm M Gregers TF Rounge TB Paulsen J Solbakken MH Sharma A Wetten OF Lanzén A Winer R Knight J Vogel JH Aken B Andersen O Lagesen K Tooming-Klunderud A Edvardsen RB Tina KG Espelund M Nepal C Previti C Karlsen BO Moum T Skage M Berg PR Gjøen T Kuhl H Thorsen J Malde K Reinhardt R Du L Johansen SD Searle S Lien S Nilsen F Jonassen I Omholt SW Stenseth NC Jakobsen KS 《Nature》2011,477(7363):207-210
Atlantic cod (Gadus morhua) is a large, cold-adapted teleost that sustains long-standing commercial fisheries and incipient aquaculture. Here we present the genome sequence of Atlantic cod, showing evidence for complex thermal adaptations in its haemoglobin gene cluster and an unusual immune architecture compared to other sequenced vertebrates. The genome assembly was obtained exclusively by 454 sequencing of shotgun and paired-end libraries, and automated annotation identified 22,154 genes. The major histocompatibility complex (MHC)?II is a conserved feature of the adaptive immune system of jawed vertebrates, but we show that Atlantic cod has lost the genes for MHC?II, CD4 and invariant chain (Ii) that are essential for the function of this pathway. Nevertheless, Atlantic cod is not exceptionally susceptible to disease under natural conditions. We find a highly expanded number of MHC?I genes and a unique composition of its Toll-like receptor (TLR) families. This indicates how the Atlantic cod immune system has evolved compensatory mechanisms in both adaptive and innate immunity in the absence of MHC?II. These observations affect fundamental assumptions about the evolution of the adaptive immune system and its components in vertebrates. 相似文献
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