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Katharina?MarquardtEmail author Gregory?S.?Rohrer Luiz?Morales Erik?Rybacki Hauke?Marquardt Brian?Lin 《Contributions to Mineralogy and Petrology》2015,170(4):40
Rocks consist of crystal grains separated by grain boundaries that impact the bulk rock properties. Recent studies on metals and ceramics showed that the grain boundary plane orientation is more significant for grain boundary properties than other characteristics such as the sigma value or disorientation (in the Earth’s science community more frequently termed misorientation). We determined the grain boundary character distribution (GBCD) of synthetic and natural polycrystalline olivine, the most abundant mineral of Earth’s upper mantle. We show that grain boundaries of olivine preferentially contain low index planes, in agreement with recent findings on other oxides (e.g. MgO, TiO2, Al2O3 etc.). Furthermore, we find evidence for a preferred orientation relationship of 90° disorientations about the [001] direction forming tilt and twist grain boundaries, as well as a preference for the 60° disorientation about the [100] axis. Our data indicate that the GBCD, which is an intrinsic property of any mineral aggregate, is fundamental for understanding and predicting grain boundary related processes. 相似文献
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Majkowska Agnieszka Kolendowicz Leszek Półrolniczak Marek Hauke Jan Czernecki Bartosz 《Theoretical and Applied Climatology》2017,127(3-4):769-777
Deforestation is expanding and accelerating into the remaining areas of undisturbed forest, and the quality of the remaining forests is declining today. Assessing the climatic impacts of deforestation can help to rectify this alarming situation. In this paper, how historical deforestation may affect global climate through interactive ocean and surface albedo is examined using an Earth system model of intermediate complexity (EMIC). Control and anomaly integrations are performed for 1000 years. In the anomaly case, cropland is significantly expanded since AD 1700. The response of climate in deforested areas is not uniform between the regions. In the background of a global cooling of 0.08 °C occurring with cooler surface air above 0.4 °C across 30° N to 75° N from March to September, the surface albedo increase has a global cooling effect in response to global-scale replacement of forests by cropland, especially over northern mid-high latitudes. The northern mid-latitude (30° N–60° N) suffers a prominent cooling in June, suggesting that this area is most sensitive to cropland expansion through surface albedo. Most regions show a consistent trend between the overall cooling in response to historical deforestation and its resulting cooling due to surface albedo anomaly. Furthermore, the effect of the interactive ocean on shaping the climate response to deforestation is greater than that of prescribed SSTs in most years with a maximum spread of 0.05 °C. This difference is more prominent after year 1800 than that before due to the more marked deforestation. These findings show the importance of the land cover change and the land surface albedo, stressing the necessity to analyze other biogeophysical processes of deforestation using interactive ocean. 相似文献
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Guiqin Wang Hauke Vollstaedt Jifeng Xu Wengui Liu 《Geostandards and Geoanalytical Research》2019,43(3):419-433
N(187Os)/N(188Os) ratios of six geological reference materials were measured using static Faraday cups (FCs) with 1013 Ω amplifiers by N‐TIMS. Our results show that the repeatability precision was 2–3‰ (2 RSD, n = 3), when taking ~ 1 g of BHVO‐2 with 76 pg g?1 of Os mass fraction and ~ 2 g of BCR‐2 with 21 pg g?1 of Os mass fraction for each sample, whether measured by FCs or by secondary electron multiplier. The repeatability precision measured by FCs was 1–0.2‰ (2 RSD, n = 3) when taking ~ 1 g of BIR‐2 with 350 pg g?1 of Os mass fraction, ~ 1 g of WGB‐1 with 493 pg g?1 of Os mass fraction or ~ 0.5 g of WPR‐1 with 13.3 ng g?1 of Os mass fraction for each sample, which is much better than those measured by secondary electron multiplier. Instead, when taking ~ 2 g of AGV‐2 with 4 pg g?1 Os mass fraction, the repeatability precision measured by secondary electron multiplier is 3–4‰ (RSD, n = 3), which is better than those measured by FCs. Of the six reference materials analysed, WPR‐1 and BIR‐1a are the most homogeneous with regard to Os isotopic composition (2 RSD of 0.08% and 0.23%, respectively) when test portion masses are 0.5–1 g. 相似文献
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Paquin Jean-Philippe Lu Youyu Taylor Stephanne Blanken Hauke Marcotte Guillaume Hu Xianmin Zhai Li Higginson Simon Nudds Shannon Chanut Jérôme Smith Gregory C. Bernier Natacha Dupont Frédéric 《Ocean Dynamics》2020,70(3):365-385
Ocean Dynamics - In the context of Canada’s Ocean Protection Plan (OPP), improved coastal and near-shore modelling is needed to enhance marine safety and emergency response capacity in the... 相似文献
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Alexander Kurnosov Hauke Marquardt Leonid Dubrovinsky Vasily Potapkin 《Comptes Rendus Geoscience》2019,351(2-3):280-285
Fiber-based laser heating systems offer high flexibility and are increasingly used in high-pressure/high-temperature research. Previous fiber-based laser heating systems were based on lasers delivering radiation with 1-μm wavelength that show unfavorable heating characteristics for many sample materials. We report on the development and first experiments of a waveguide (fiber)-based CO2-laser heating system that can be used in a flexible manner for high-temperature research and for high-pressure/temperature experiments when combined with diamond-anvil cells. The waveguide-based CO2-laser heating system allows convenient heating of optically transparent samples without the need for adding an additional laser absorber. In a pilot experiment, the flexible heating system has been installed on a Brillouin scattering system to measure high-temperature sound-wave velocities in single-crystal MgO. The waveguide-based CO2-laser heating system offers perspectives for a variety of scientific applications, most importantly those that require the use of synchrotron facilities where space is limited and flexible solutions are required. 相似文献
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This article presents a US perspective on the influence of government policies on the nature and development of advanced marine electronic instrumentation (MEI) technologies in Europe. US firms traditionally have enjoyed a strong international competitive advantage in the MEI field, but European institutions are undergoing rapid changes that may affect the competitive position of firms in advanced technology industries. These include the consolidation of firms in specific markets and the increased emphasis on centralized, collaborative ‘technology transfer’ research efforts across sectors and across national borders. We expect broadly defined marine markets to grow in Europe. The best policy for US firms may well be one of cautious optimism and close attention to the potential for business relationships with established and emerging European firms. 相似文献
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Coupled thermal-orbital evolution models of Europa and Io are presented. It is assumed that Io, Europa, and Ganymede evolve in the Laplace resonance and that tidal dissipation of orbital energy is an internal heat source for both Io and Europa. While dissipation in Io occurs in the mantle as in the mantle dissipation model of Segatz et al. (1988, Icarus 75, 187), two models for Europa are considered. In the first model dissipation occurs in the silicate mantle while in the second model dissipation occurs in the ice shell. In the latter model, ice shell melting and variations of the shell thickness above an ocean are explicitly included. The rheology of both the ice and the rock is cast in terms of a viscoelastic Maxwell rheology with viscosity and shear modulus depending on the average temperature of the dissipating layer. Heat transfer by convection is calculated using a parameterization for strongly temperature-dependent viscosity convection. Both models are consistent with the present orbital elements of Io, Europa, and Ganymede. It is shown that there may be phases of quasi-steady evolution with large or small dissipation rates (in comparison with radiogenic heating), phases with runaway heating or cooling and oscillatory phases during which the eccentricity and the tidal heating rate will oscillate. Europa's ice thickness varies between roughly 3 and 70 km (dissipation in the silicate layer) or 10 and 60 km (dissipation in the ice layer), suggesting that Europa's ocean existed for geological timescales. The variation in ice thickness, including both convective and purely conductive phases, may be reflected in the formation of different geological surface features on Europa. Both models suggest that at present Europa's ice thickness is several tens of km thick and is increasing, while the eccentricity decreases, implying that the satellites evolve out of resonance. Including lithospheric growth in the models makes it impossible to match the high heat flux constraint for Io. Other heat transfer processes than conduction through the lithosphere must be important for the present Io. 相似文献
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Christiane Schröder Ina Pokorny Nicola Dolgener Christoph Herden Hauke Drews Ralph Tiedemann 《Limnologica》2012,42(4):291-298
The ongoing global amphibian decline calls for an increase of habitat and population management efforts. Pond restoration and construction is more and more accompanied by breeding and translocation programs. However, the appropriateness of translocations as a tool for conservation has been widely debated, as it can cause biodiversity loss through genetic homogenization and can disrupt local adaptation, eventually leading to outbreeding depression. In this study, we investigated the genetic structure of two translocated populations of the critically endangered fire-bellied toad Bombina bombina at its north western distribution edge using supposedly neutral genetic markers (variation in the mitochondrial control region and microsatellites) as well as a marker under selection (major histocompatibility complex (MHC) genes). While one of the newly established populations showed the typical genetic composition of surrounding populations, the other was extremely diverged without clear affinity to its putative source. In this population we detected a profound impact of allochthonous individuals: 100% of the analyzed individuals exhibited a highly divergent mitochondrial haplotype which was otherwise found in Austria. 83% of them were also assigned to Austria by the analysis of microsatellites. Interestingly, for the adaptive marker (MHC) local alleles were predominant in this population, while only very few alleles were shared with the Austrian population. Probably Mendelian inheritance has reshuffled genotypes such that adaptive local alleles are maintained (here, MHC), while presumably neutral allochthonous alleles dominate at other loci. The release of allochthonous individuals generally increased the genetic variability of the affected population without wiping out locally adaptive genotypes. Thus, outbreeding depression might be less apparent than sometimes thought and natural selection appears strong enough to maintain locally adaptive alleles, at least in functionally important immune system genes. 相似文献