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Iverson RM Dzurisin D Gardner CA Gerlach TM LaHusen RG Lisowski M Major JJ Malone SD Messerich JA Moran SC Pallister JS Qamar AI Schilling SP Vallance JW 《Nature》2006,444(7118):439-443
The 2004-05 eruption of Mount St Helens exhibited sustained, near-equilibrium behaviour characterized by relatively steady extrusion of a solid dacite plug and nearly periodic shallow earthquakes. Here we present a diverse data set to support our hypothesis that these earthquakes resulted from stick-slip motion along the margins of the plug as it was forced incrementally upwards by ascending, solidifying, gas-poor magma. We formalize this hypothesis with a dynamical model that reveals a strong analogy between behaviour of the magma-plug system and that of a variably damped oscillator. Modelled stick-slip oscillations have properties that help constrain the balance of forces governing the earthquakes and eruption, and they imply that magma pressure never deviated much from the steady equilibrium pressure. We infer that the volcano was probably poised in a near-eruptive equilibrium state long before the onset of the 2004-05 eruption. 相似文献
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Lobov IB Rao S Carroll TJ Vallance JE Ito M Ondr JK Kurup S Glass DA Patel MS Shu W Morrisey EE McMahon AP Karsenty G Lang RA 《Nature》2005,437(7057):417-421
Macrophages have a critical role in inflammatory and immune responses through their ability to recognize and engulf apoptotic cells. Here we show that macrophages initiate a cell-death programme in target cells by activating the canonical WNT pathway. We show in mice that macrophage WNT7b is a short-range paracrine signal required for WNT-pathway responses and programmed cell death in the vascular endothelial cells of the temporary hyaloid vessels of the developing eye. These findings indicate that macrophages can use WNT ligands to influence cell-fate decisions--including cell death--in adjacent cells, and raise the possibility that they do so in many different cellular contexts. 相似文献
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Mutations in ENPP1 are associated with 'idiopathic' infantile arterial calcification 总被引:8,自引:0,他引:8
Rutsch F Ruf N Vaingankar S Toliat MR Suk A Höhne W Schauer G Lehmann M Roscioli T Schnabel D Epplen JT Knisely A Superti-Furga A McGill J Filippone M Sinaiko AR Vallance H Hinrichs B Smith W Ferre M Terkeltaub R Nürnberg P 《Nature genetics》2003,34(4):379-381
Idiopathic infantile arterial calcification (IIAC; OMIM 208000) is characterized by calcification of the internal elastic lamina of muscular arteries and stenosis due to myointimal proliferation. We analyzed affected individuals from 11 unrelated kindreds and found that IIAC was associated with mutations that inactivated ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1). This cell surface enzyme generates inorganic pyrophosphate (PP(i)), a solute that regulates cell differentiation and serves as an essential physiologic inhibitor of calcification. 相似文献
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