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271.
Denise Christina Rüther Rune Mattingsdal Karin Andreassen Matthias Forwick Katrine Husum 《Quaternary Science Reviews》2011,30(19-20):2776-2792
A 280 km wide sediment wedge in outer Bjørnøyrenna (Bear Island Trough), south-western Barents Sea, has been investigated using 2D and 3D seismic data, sediment gravity cores, as well as regional swath and large scale bathymetry data. The bathymetry data indicate a division into an up to 35 m high frontal wedge with large depressions, and an upstream part characterized by mega scale glacial lineations (MSGL). From seismic sections increasing erosion is demonstrated for the upstream part, coinciding with the location of MSGL. Whether the latter are depositional features postdating an extensive erosional event or formed by erosion remains inconclusive. Based on the distinct morphology and internal structures, we infer that the system was deposited during a rapid readvance whereby the ice front pushed and bulldozed predominantly soft, diluted proglacial sediments. Analyses in the eastern part of the sediment system reveal the existence of imbricated thrust sheets in the frontal part of the wedge. This is suggested to imply upstream erosion of sedimentary rock and incorporation of thrusted blocks into the moraine, forming a composite ridge locally. We argue that observed large scale depressions are dead-ice features in the marine environment. It is envisioned that intense englacial thrusting may have developed into a decollement as the cold glacier snout got overrun by ice masses from the interior, thereby enabling the inclusion of slabs of ice in the push moraine mass. Radiocarbon dates indicate that the sediment wedge was deposited around 17,090 cal yrs BP (14,530 14C yrs BP) and that the ice front probably remained stable until 16,580 cal yrs BP (13,835 14C yrs BP). 相似文献
272.
Matthias Steinmetz 《Astrophysics and Space Science》2003,284(2):325-334
I review success and failure of the hierarchical galaxy formation model. In this scenario, the morphology of galaxies is regulated
by the mode of gas accretion and intimately linked to discrete accretion events. Some of the common misconceptions about hierarchical
clustering are discussed. The need of a self-consistent approach that incorporates the chemical and dynamical evolution on
small scalessimultaneously with the cosmological framework of structure formation on large scales is emphasized.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
273.
Philippe Morel Friedhelm von Blanckenburg Mirjam Schaller † Peter W. Kubik Matthias Hinderer 《地学学报》2003,15(6):398-404
Cosmogenic nuclides, measured in quartz from recent river bedload, provide a novel tool to quantify catchment‐wide erosion rates at geologically meaningful time scales. Here we present an analysis of the geomorphological evolution of the 350 km2 Wutach catchment in the uplands of the south‐west German Black Forest. The robustness of the method is demonstrated by the fact that, although the area was affected by river capture at 18 kyr bp , the formed gorge is so narrow that spatially averaged erosion rates were not resolvably perturbed. However, because cosmogenic nuclides preserve an erosion memory of several thousand years, the only perturbation introduced was detected in the minor areas that have been subject to the last maximum glaciation. In unglaciated areas, an important relationship between lithology and erosion can by quantified: sandstone lithologies erode at 12–18 mm kyr?1, granite lithologies at 35–47 mm kyr?1 and limestone lithologies (as deduced from river load gauging) at 70–90 mm kyr?1. 相似文献
274.
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277.
Josep M. Trigo‐Rodríguez Jordi Llorca Mona Weyrauch Addi Bischoff Carles E. Moyano‐Cambero Klaus Keil Matthias Laubenstein Andreas Pack José María Madiedo Jacinto Alonso‐Azcárate My Riebe Rainer Wieler Uli Ott Mar Tapia Narcís Mestres 《Meteoritics & planetary science》2014,49(8):1475-1484
We report and describe an L6 ordinary chondrite fall that occurred in Ardón, León province, Spain (longitude 5.5605°W, latitude 42.4364°N) on July 9th, 1931. The 5.5 g single stone was kept hidden for 83 yr by Rosa González Pérez, at the time an 11 yr old who had observed the fall and had recovered the meteorite. According to various newspaper reports, the event was widely observed in Northern Spain. Ardón is a very well‐preserved, fresh, strongly metamorphosed (petrologic type 6), and weakly shocked (S3) ordinary chondrite with well‐equilibrated and recrystallized minerals. The mineral compositions (olivine Fa23.7±0.3, low‐Ca pyroxene Fs20.4±0.2Wo1.5±0.2, plagioclase An10.3±0.5Ab84.3±1.2), magnetic susceptibility (log χ = 4.95 ± 0.05 × 10?9 m3 kg?1), bulk density (3.49 ± 0.05 g cm?3), grain density (3.58 ± 0.05 g cm?3), and porosity (2.5 vol%) are typical for L6 chondrites. Short‐lived radionuclides confirm that the meteorite constitutes a recent fall. The 21Ne and 38Ar cosmic ray exposure ages are both about 20–30 Ma, similar to values for many other L chondrites. The cosmogenic 22Ne/21Ne ratio indicates that preatmospheric Ardón was a relatively large body. The fact that the meteorite was hidden in private hands for 83 yr makes one wonder if other meteorite falls may have experienced the same fate, thus possibly explaining the anomalously low number of falls reported in continental Spain in the 20th century. 相似文献
278.
Technology transfer (TT) is not mandatory for Clean Development Mechanism (CDM) projects, yet proponents of CDM argue that TT in CDM can bring new technologies to developing countries and thus not only reduce emissions but also foster development. We review the quantitative literature on determinants of TT in CDM and estimate determinants for CDM projects in China. China is by far the largest host country of CDM projects and it is therefore crucial to understand the factors that drive TT there. To gain better interpretation, we focus on heterogeneity within a single country and results can thus be linked to specific policies of the country. Our probit estimations confirm previous international cross-country studies, indicating that larger projects and more advanced technologies are more likely to involve TT. In addition, we find evidence that agglomeration effects are more pronounced at the province level rather than larger regions. We also find a positive effect of foreign direct investment (FDI) on TT, and academic research and development (R&D) is complementary to TT.Policy relevanceTechnology transfer (TT) is a goal of Chinese CDM legislation, but it is not a prerequisite for project approval. Our estimations show the project specific, technological and region-specific features that encourage more TT among CDM projects. Some variables analysed such as R&D spending and FDI (both are found to have positive effects on TT) can be, to some extent, influenced by the policy-makers. Moreover, we find some evidence for the presence of negative agglomeration effects on the provincial level: the likelihood of TT is decreasing in the number of previous projects operating in the same technology and province. This finding needs to be interpreted with great caution. It may suggest the existence of a learning externality, which could serve as a justification for policy intervention. Any policy intervention requires however careful analysis of potential positive or negative externalities resulting from the agglomeration of CDM projects and a comparison of possible benefits with the costs of TT. 相似文献
279.
We investigated an alternative means for quantifying daytime ecosystem respiration from eddy-covariance data in three forests with different canopy architecture. Our hypothesis was that the turbulent transport by coherent structures is the main pathway for carrying detectable sub-canopy respiration signals through the canopy. The study extends previously published work by incorporating state-of-the-art wavelet decomposition techniques for the detection of coherent structures. Further, we investigated spatial and temporal variability of the respiration signal and coherent exchange at multiple heights, for three mature forest sites with varying canopy and terrain properties for one summer month. A connection between the coherent structures and identified sub-canopy respiration signal was clearly determined. Although not always visible in signals collected above the canopy, certain cases showed a clear link between conditionally sampled respiration events and coherent structures. The dominant time scales of the coherent structure ejection phase (20?C30 s), relative timing of maximum coincidence between respiration events and the coherent structure ejection phase (at approximately ?10 s from detection) and vertical transport upward through the canopy were shown to be consistent in time, across measurement heights and across the different forest sites. Best results were observed for an open canopy pine site. We conclude that the presented method is likely to be applicable at more open rather than dense (closed) canopies. The results provided a confirmation of the connection between below- and above-canopy scalar time series, and may help the development or refinement of direct methods for the determination of component fluxes from observations above the canopy. 相似文献
280.
Ludovic Puig Kate Isaak Martin Linder Isabel Escudero Pierre-Elie Crouzet Roger Walker Matthias Ehle Jutta Hübner Rainer Timm Bram de Vogeleer Pierre Drossart Paul Hartogh Christophe Lovis Giusi Micela Marc Ollivier Ignasi Ribas Ignas Snellen Bruce Swinyard Giovanna Tinetti Paul Eccleston 《Experimental Astronomy》2015,40(2-3):393-425