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The Fish Canyon Magma Body, San Juan Volcanic Field, Colorado: Rejuvenation and Eruption of an Upper-Crustal Batholith 总被引:14,自引:9,他引:14
More than 5000 km3 of nearly compositionally homogeneous crystal-richdacite ( 相似文献
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G.K. PLATTNER F. JOOS T. F. STOCKER O. MARCHAL 《Tellus. Series B, Chemical and physical meteorology》2001,53(5):564-592
Global warming simulations are performed with a coupled climate model of reduced complexity to investigate global warming–marine carbon cycle feedbacks. The model is forced by emissions of CO2 and other greenhouse agents from scenarios recently developed by the Intergovernmental Panel on Climate Change and by CO2 stabilization profiles. The uptake of atmospheric CO2 by the ocean is reduced between 7 to 10% by year 2100 compared to simulations without global warming. The reduction is of similar size in the Southern Ocean and in low‐latitude regions (32.5°S‐32.5°N) until 2100, whereas low‐latitude regions dominate on longer time scales. In the North Atlantic the CO2 uptake is enhanced, unless the Atlantic thermohaline circulation completely collapses. At high latitudes, biologically mediated changes enhance ocean CO2 uptake, whereas in low‐latitude regions the situation is reversed. Different implementations of the marine biosphere yield a range of 5 to 16% for the total reduction in oceanic CO2 uptake until year 2100. Modeled oceanic O2 inventories are significantly reduced in global warming simulations. This suggests that the terrestrial carbon sink deduced from atmospheric O2 /N2 observations is potentially overestimated if the oceanic loss of O2 to the atmosphere is not considered. 相似文献
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Regularized discriminant analysis has proven to be a most effective classifier for problems wheretraditional classifiers fail because of a lack of sufficient training samples,as is often the case in high-dimensional settings.However,it has been shown that the model selection procedure of regularizeddiscriminant analysis,determining the degree of regularization,has some deficiencies associated with it.We propose a modified model selection procedure based on a new appreciation function.By means ofan extensive simulation it was shown that the new model selection procedure performs better than theoriginal one.We also propose that one of the control parameters of regularized discriminant analysis beallowed to take on negative values.This extension leads to an improved performance in certain situations.The results are confirmed using two chemical data sets. 相似文献
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GUILLAUME CAILLEAU ERIC P. VERRECCHIA OLIVIER BRAISSANT† LAURENT EMMANUEL‡ 《Sedimentology》2009,56(6):1858-1875
Needle fibre calcite is one of the most ubiquitous habits of calcite in vadose environments (caves deposits, soil pores, etc.). Its origin, either through inorganic, indirect or direct biological processes, has long been debated. In this study, investigations at 11 sites in Europe, Africa and Central America support arguments for its biogenic origin. The wide range of needle morphologies is the result of a gradual evolution of the simplest type, a rod. This rod is the elementary brick which, by aggregation and welding, builds more complex needles. The absence of cross‐welded needles implies that they are welded in a mould, or under a longitudinal and unidirectional constraint, before being released inside the soil pores. The difference between the lengthening of the needles and the c axis can be explained by the existence of needles observed under a scanning electron microscope in organic sleeves, which can act as a mould during rod growth. Complex morphologies with epitaxial outgrowths on straight rods cannot have grown entirely inside organic microtubes; they must result from soil diagenesis after the release of straight rods in a soil‐free medium. Whisker crystals are interpreted as the result of growth and coalescence of euhedral crystals on a rod. Rhomb chains are considered to be the consequence of successive epitaxial growth steps on a needle during variations in growth conditions. Isotopic signatures for needle fibre calcite vary from ?16·63‰ to +1·10‰ and from ?8·63‰ to ?2·25‰ for δ13C and δ18O, respectively. The absence of high δ18O values for needle fibre calcite precludes a purely physicochemical origin (evaporative) for this particular habit of calcite. As epitaxial growth cannot precipitate in the same conditions as initial needles, needle fibre calcite stable isotopic signatures should be used with caution as a proxy for palaeoenvironmental reconstructions. In addition, it is suggested that the term needle fibre calcite should be kept for the original biogenic form. The other habit should be referred to as epitaxial forms of needle fibre calcite. 相似文献
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The sulfate-CCN-cloud albedo effect 总被引:7,自引:0,他引:7
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Comparison of the radiative properties and direct radiative effect of aerosols from a global aerosol model and remote sensing data over ocean 总被引:1,自引:1,他引:1
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