Dental mesowear reflects local vegetation and niche separation in Pleistocene proboscideans from Britain          下载免费PDF全文

Juha Saarinen  Adrian M. Lister 《第四纪科学杂志》2016,31(7):799-808

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The baryon fraction of ΛCDM haloes     

Robert A. Crain  Vincent R. Eke  Carlos S. Frenk  Adrian Jenkins  Ian G. McCarthy  Julio F. Navarro  Frazer R. Pearce 《Monthly notices of the Royal Astronomical Society》2007,377(1):41-49

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Carbon dioxide,methane, and dissolved carbon dynamics in an urbanized river system     

Chao Gu  Susan Waldron  Adrian Michael Bass 《水文研究》2021,35(9):e14360

Estimates of greenhouse gas evasion from rivers have been refined over the past decades to constrain their role in global carbon cycle processes. However, despite 55% of the human population living in urban areas, urban rivers have had limited attention. We monitored carbon dynamics in an urbanized river (River Kelvin, 331 km², UK) to explore the drivers of dissolved carbon lateral and vertical export. Over a 2-year sampling period, riverine methane (CH₄) and carbon dioxide (CO₂) concentrations were consistently oversaturated with respect to atmospheric equilibria, leading to continual degassing to the atmosphere. Carbon stable isotopic compositions (δ¹³C) indicated that terrestrially derived carbon comprised most of the riverine CH₄ and dissolved CO₂ (CO₂*) load while dissolved inorganic carbon (DIC) from groundwater was the main form of riverine DIC. The dynamics of CH₄, CO₂*, and DIC in the river were primarily hydrology-controlled, that is, [CH₄] and [CO₂*] both increased with elevated discharge, total [DIC] decreased with elevated discharge while the proportion of biologically derived DIC increased with increasing discharge. The concentration of dissolved organic carbon (DOC) showed a weak relationship with river hydrology in summer and autumn and was likely influenced by the combined sewer overflows. Carbon emission to the atmosphere is estimated to be 3.10 ± 0.61 kg C·m⁻²·yr⁻¹ normalized to water surface area, with more than 99% emitted as CO₂. Annual carbon loss to the coastal estuary is approximately 4.69 ± 0.70 Gg C yr⁻¹, with annual DIC export approximately double that of DOC. Per unit area, the River Kelvin was a smaller carbon source to the atmosphere than natural rivers/streams but shows elevated fluxes of DIC and DOC under comparable conditions. This research illustrates the role urban systems may have on riverine carbon dynamics and demonstrates the potential tight link between urbanization and riverine carbon export.  相似文献   

The diurnal cycle of marine cloud feedback in climate models     

Mark J. Webb  Adrian P. Lock  Alejandro Bodas-Salcedo  Sandrine Bony  Jason N. S. Cole  Tsuyoshi Koshiro  Hideaki Kawai  Carlo Lacagnina  Frank M. Selten  Romain Roehrig  Bjorn Stevens 《Climate Dynamics》2015,44(5-6):1419-1436

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酸洗法测定海洋沉积物有机碳和无机碳含量的致命缺陷   总被引：2，自引：0，他引：2  

凌晨  刘志飞  张靖雯  赵玉龙  张艳伟  Fernandez Adrian R. 《海洋学报(英文版)》2020,39(8):96-102

Organic and inorganic carbon contents of marine sediments are important to reconstruct marine productivity,global carbon cycle, and climate change. A proper method to separate and determine organic and inorganic carbons is thus of great necessity. Although the best method is still disputable, the acid leaching method is widely used in many laboratories because of its ease-of-use and high accuracy. The results of the elemental analysis of sediment trap samples reveal that organic and inorganic carbon contents cannot be obtained using the acid leaching method, causing an infinitely amplified error when the carbon content of the decarbonated sample is 12%±1% according to a mathematical derivation. Acid fumigation and gasometric methods are used for comparison, which indicates that other methods can avoid this problem in organic carbon analysis. For the first time, this study uncovers the pitfalls of the acid leaching method, which limits the implication in practical laboratory measurement, and recommends alternative solutions of organic/inorganic carbon determination in marine sediments.  相似文献   

Evaluation of the thermal conductivity of sandstone solid skeleton using the concept of equivalent microstructure     

Łydżba  Dariusz  Różański  Adrian  Sevostianov  Igor  Stefaniuk  Damian 《Acta Geotechnica》2022,17(11):5059-5072

Acta Geotechnica - We evaluate thermal conductivity of the skeleton of porous sandstone from the measurements of the effective thermal conductivities of dry and saturated specimens provided by...  相似文献   

Microstructural evidence for a disequilibrium condensation origin for hibonite‐spinel inclusions in the ALHA77307 CO3.0 chondrite          下载免费PDF全文

Jangmi Han  Adrian J. Brearley  Lindsay P. Keller 《Meteoritics & planetary science》2015,50(12):2121-2136

Two hibonite‐spinel inclusions (CAIs 03 and 08) in the ALHA77307 CO3.0 chondrite have been characterized in detail using the focused ion beam sample preparation technique combined with transmission electron microscopy. These hibonite‐spinel inclusions are irregularly shaped and porous objects and consist of randomly oriented hibonite laths enclosed by aggregates of spinel with fine‐grained perovskite inclusions finally surrounded by a partial rim of diopside. Melilite is an extremely rare phase in this type of CAI and occurs only in one inclusion (CAI 03) as interstitial grains between hibonite laths and on the exterior of the inclusion. The overall petrologic and mineralogical observations suggest that the hibonite‐spinel inclusions represent high‐temperature condensates from a cooling nebular gas. The textural relationships indicate that hibonite is the first phase to condense, followed by perovskite, spinel, and diopside. Texturally, melilite condensation appears to have occurred after spinel, suggesting that the condensation conditions were far from equilibrium. The crystallographic orientation relationships between hibonite and spinel provide evidence of epitaxial nucleation and growth of spinel on hibonite surfaces, which may have lowered the activation energy for spinel nucleation compared with that of melilite and consequently inhibited melilite condensation. Hibonite contains abundant stacking defects along the (001) plane consisting of different ratios of the spinel and Ca‐containing blocks within the ideal hexagonal hibonite structure. This modification of the stacking sequence is likely the result of accommodation of excess Al in the gas into hibonite due to incomplete condensation of corundum from a cooling gas under disequilibrium conditions. We therefore conclude that these two hibonite‐spinel inclusions in ALHA77307 formed by high‐temperature condensation under disequilibrium conditions.  相似文献   

Satellite laser ranging to GPS and GLONASS   总被引：5，自引：4，他引：1  

Krzysztof Sośnica  Daniela Thaller  Rolf Dach  Peter Steigenberger  Gerhard Beutler  Daniel Arnold  Adrian Jäggi 《Journal of Geodesy》2015,89(7):725-743

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GOCE: assessment of GPS-only gravity field determination   总被引：2，自引：1，他引：1  

Adrian Jäggi  H. Bock  U. Meyer  G. Beutler  J. van den IJssel 《Journal of Geodesy》2015,89(1):33-48

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The Restricted Three-Body Problem: Comments on the Rotational Effect     

Rodica Roman  Sorin Adrian Roman 《Astrophysics and Space Science》2006,301(1-4):179-184

The synchronization between the orbital motion and axial rotation of the two component stars of a binary system is reviewed. Some previous published papers are mentioned and the general conclusion is outlined: If we shall use a rotating coordinate system synchronous with one of the two stellar axial rotations, it is not possible to obtain a Jacobi integral and the Roche geometry cannot be further analyzed. In addition, a theoretical approach is summarized in order to use the axial rotations of the two component stars, even if the constants of the stellar structure (k₂)₁, (k₂)₂must be taken into consideration. So it is found that if the stellar angular velocities are higher than the corresponding Keplerian angular velocity (ω_i≫ ω_k, i= ), the problem of the rotational effect could be of practical consideration. Finally, a theoretical relationship between the two constants (k₂)₁and (k₂)₂of the stellar structure is established.  相似文献