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The Mangshan Plateau is located on the south bank of the Huang He (Yellow River) just west of the city of Zhengzhou, well outside the Loess Plateau in central China. Mixing models of the grain‐size data indicate that the loess deposits are mixtures of three loess components. Comparison of the mixing model with existing models established for a series of loess–palaeosol sequences from the Loess Plateau indicates that the Mangshan loess has been supplied from a proximal dust source, the Huang He floodplain, during major dust outbreaks. The high accumulation rates, the composition of the loess components, and especially the high proportions of a sandy loess component support this. Owing to the exceptionally high accumulation rates, the Mangshan grain size, magnetic susceptibility and carbonate records provide a high‐resolution archive of environmental and climate change. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   
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Abstract— The mineral compositions of 250 micrometeorites have been studied and olivines and low-calcium pyroxenes with crystals larger than 5 μm have been analyzed. While magnesium-rich grains dominate, the Fa content of olivine may reach 50% and the Fs content of pyroxene may reach 26%. The Ca and Mn of the olivine show no consistent trends with increasing Fe, but Cr shows a negative correlation. For low-Ca pyroxene, Al and Cr contents are generally higher than in pyroxenes of equilibrated chondrites but similar to those of highly unequilibrated chondrites. Calcium-bearing pyroxene, feldspar and chromite are rare in the micrometeorites which were selected because of their high Mg, Si, Fe and their low Ca and Al content. All these minerals are found as coarse-grained particles often with adhering iron-rich scoria or as clasts in fine-grained or scoriaceous micrometeorites. Apart from a few particles which could be the debris of ordinary chondrites, most micrometeorites probably come from a common source similar, but not identical to carbonaceous chondrites, as shown by their lower Ni and S content and their different oxygen isotopic composition assuming two measurements performed on olivine grains prove to be typical.  相似文献   
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We present warm dark matter (WDM) as a possible solution to the missing satellites and angular momentum problem in galaxy formation and introduce improved initial conditions for numerical simulations of WDM models, which avoid the formation of unphysical haloes found in earlier simulations. There is a hint, that because of that the mass function of satellite haloes has been overestimated so far, pointing to higher values for the WDM particle mass. This revised version was published online in August 2006 with corrections to the Cover Date.  相似文献   
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With the Planck and Herschel satellite missions of the European Space Agency, the far-infrared and submillimeter window will offer new investigation tools toward clusters of galaxies in the distant Universe. These are the Sunyaev Zel'dovich (SZ) effect of the cosmic microwave background and the thermal emission of dust grains. The power of the SZ effect is such that Planckis expected to discover thousands of new clusters at redshifts larger than 0.2, where only a few tens are known today. The dust can be present at large scale in the intracluster medium, and we show that even at very low abundances it is able to be a major cooling agent for the whole cluster. However the dominating dust emission will be that of the background infrared star forming galaxies. In all cases, the data processing of space borne sensitive submillimeter observations of clusters of galaxies such as the one that Planck and Herschel will provide, will require a very carefull combined analysis of the SZ effect and dust thermal emission.  相似文献   
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