Weighting climate model ensembles for mean and variance estimates     

Ned Haughton  Gab Abramowitz  Andy Pitman  Steven J. Phipps 《Climate Dynamics》2015,45(11-12):3169-3181

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Etching of fission tracks in monazite: An experimental study     

Sean Jones  Andy Gleadow  Barry Kohn  Steven M. Reddy 《地学学报》2019,31(3):179-188

This study reports a range of etching and annealing experiments to establish the optimum conditions for the etching of fission tracks in monazite. The previously reported concentrated (12 M) HCl etchant at 90°C was found to cause grain loss from epoxy mounts and high degrees of grain corrosion, as did much longer etching times at lower temperatures. Using implanted ²⁵²Cf semi‐tracks, a series of experiments were performed on internal prismatic faces of monazite‐(Ce) crystals from the Palaeozoic Harcourt Granodiorite (Victoria, Australia) using an alternative 6 M HCl etchant, also at 90°C. Step‐etch results show optimal etching at 60–90 min. Further, an isothermal annealing experiment illustrated that the degree of annealing that can be expected during etching at 90°C under laboratory time scales is negligible. The etching rate between grains is not uniform, with a correlation demonstrated between over‐etched grains and high U and Th concentrations.  相似文献   

NEWS     

Andy Millington  Fred Roots  Peter J. Lamb  S. Dyck 《水文科学杂志》2013,58(4):389-390

ABSTRACT

A stochastic model is proposed to describe flood-induced changes in cross sections of ephemeral streams with coarse bed-material. The model is based on the assumption that the real process can be described as a marked point process. The cumulative distribution functions of both the total change in a fixed interval of time and the maximum scour in the same period were examined. The model was run, using Monte Carlo techniques, with field data obtained from a small stream in southern Italy.  相似文献   

Reply to comment on `European provenance of the Numidian Flysch in northern Tunisia'     

Dorrik Stow  Christine Fildes  Sami Riahi  Mohamed Soussi  Urval Patel  J. Andy Milton  Stuart Marsh 《地学学报》2010,22(6):504-505

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Southern African topography and erosion history: plumes or plate tectonics?     

Andy Moore  Tom Blenkinsop  Fenton Cotterill 《地学学报》2009,21(4):310-315

The physiography of southern Africa comprises a narrow coastal plain, separated from an inland plateau by a horseshoe-shaped escarpment. The interior of the inland plateau is a sedimentary basin. The drainage network of southern Africa is characterized by three river divides, broadly parallel to the coastline. These features contrast strongly with the broad dome and radial drainage patterns predicted by models which ascribe the physiography of southern Africa to uplift over a deep mantle plume. The drainage divides are interpreted as axes of epeirogenic uplift. The ages of these axes, which young from the margin to the interior, correlate closely with major reorganizations of spreading regimes in the oceanic ridges surrounding southern Africa, suggesting an origin from stresses related to plate motion. Successive epeirogenic uplifts of southern Africa on the axes, forming the major river divides, initiated cyclic episodes of denudation, which are coeval with erosion surfaces recognized elsewhere across Africa.  相似文献   

MODFLOW procedure to simulate axisymmetric flow in radially heterogeneous and layered aquifer systems     

Andy Louwyck  Alexander Vandenbohede  Mark Bakker  Luc Lebbe 《Hydrogeology Journal》2014,22(5):1217-1226

A procedure is outlined to simulate axisymmetric groundwater flow in radially heterogeneous and layered aquifer systems using the unmodified version of MODFLOW. The procedure is straightforward, as it only requires correction of some of the input parameters. In contrast to other MODFLOW procedures to simulate axisymmetric flow, no restrictions are imposed on the type of flow, the discretization of radial distance, or the parameter values. Hence, the method can deal with both confined and unconfined flow, wellbore storage, and axisymmetric aquifer inhomogeneities including effects of finite-thickness skin and gravel pack. Several test cases are presented, which compare the calculated results with existing analytical solutions, the analytic element solver TTim, and the axisymmetric, finite-difference model MAxSym. It is concluded that the MODFLOW procedure is capable of simulating accurately axisymmetric flow in radially heterogeneous multi-aquifer systems.  相似文献   

Estrogen receptor (ER) agonists and androgen receptor (AR) antagonists in effluents from Norwegian North Sea oil production platforms   总被引：6，自引：0，他引：6  

Tollefsen KE  Harman C  Smith A  Thomas KV 《Marine pollution bulletin》2007,54(3):277-283

The in vitro estrogen receptor (ER) agonist and androgen receptor (AR) antagonist potencies of offshore produced water effluents collected from the Norwegian Sector were determined using recombinant yeast estrogen and androgen screens. Solid phase extraction (SPE) concentrates of the effluents showed E2 agonist activities similar to those previously reported for the United Kingdom (UK) Continental Shelf (<0.1-4 ng E2 L(-1)). No activity was detected in the filtered oil droplets suggesting that produced water ER activity is primarily associated with the dissolved phase. Targeted analysis for methyl- to nonyl-substituted alkylphenol isomers show the occurrence of known ER agonists in the analysed samples. For the first time, AR antagonists were detected in both the dissolved and oil associated phase at concentrations of between 20 and 8000 microg of flutamide equivalents L(-1). The identity of the AR antagonists is unknown, however this represents a significant input into the marine environment of unknown compounds that exert a known biological effect. It is recommended that further analysis using techniques such as bioassay-directed analysis is performed to identify the compounds/groups of compounds that are responsible in order to improve the assessment of the risk posed by produced water discharges to the marine environment.  相似文献   

The Terrestrial Biosphere: Environmental Change, Ecosystem Change, Attitudes and Values: By Steve Trudgill.     

Andy Kliskey 《New Zealand geographer》2001,57(2):52-52

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Skills constraints and the low carbon transition     

Nick Jagger  Tim Foxon  Andy Gouldson 《Climate Policy》2013,13(1):43-57

Achieving a successful transition to a low carbon economy, in the UK and other countries, will require sufficient people with appropriate qualifications and skills to manufacture, install, and operate the low carbon technologies and approaches. The actual numbers and types of skills required are uncertain and will depend on the speed and direction of the transition pathways, but there are reasons to doubt that market mechanisms will deliver the necessary skilled workers in a timely manner. The range of market, government, and governance failures relating to the provision of low carbon skills are examined, particularly for their potential to cause a slower, costlier, and less employment-intensive transition. The potential policy responses to these failures are considered, including standardization of funding for training; formalization of transferable qualifications; legally binding targets for carbon emissions reductions and low carbon technology deployment; framework contracts and agreements between actors in key sectors; licensing and accreditation schemes for key technology sectors; government support for skills academies and training centres; support for first movers in niches; increasing mobility of workers; and providing a clear long-term cross-sectoral framework for a low carbon transition, including skills training.

Policy relevance

The article argues for the importance of skills issues for a successful transition to a low carbon economy. It outlines the potential causes of skills shortages, both generic and those specific to low carbon, as well as the probable impact of these types of shortages. By changing existing sectoral and occupational patterns, the transition will disrupt the existing market and government mechanisms to identify and remedy skills shortages in specific sectors. The nature and required pace of the low carbon transition also means that there are pressures that could induce greater skills shortages. These shortages, in turn, could critically delay elements of the transition and increase its cost and duration. The article outlines approaches taken to address these causes of skills shortages, drawing on examples from UK low carbon policy. The article ends with an argument that skills issues need to be more central to transitions debates.  相似文献   

Igneous and shock processes affecting chassignite amphibole evaluated using chlorine/water partitioning and hydrogen isotopes          下载免费PDF全文

Paul A. Giesting  Susanne P. Schwenzer  Justin Filiberto  Natalie A. Starkey  Ian A. Franchi  Allan H. Treiman  Andy G. Tindle  Monica M. Grady 《Meteoritics & planetary science》2015,50(3):433-460

Amphibole in chassignite melt inclusions provides valuable information about the volatile content of the original interstitial magma, but also shock and postshock processes. We have analyzed amphibole and other phases from NWA 2737 melt inclusions, and we evaluate these data along with published values to constrain the crystallization Cl and H₂O content of phases in chassignite melt inclusions and the effects of shock on these amphibole grains. Using a model for the Cl/OH exchange between amphibole and melt, we estimate primary crystallization OH contents of chassignite amphiboles. SIMS analysis shows that amphibole from NWA 2737 currently has 0.15 wt% H₂O. It has lost ~0.6 wt% H₂O from an initial 0.7–0.8 wt% H₂O due to intense shock. Chassigny amphibole had on average 0.3–0.4 wt% H₂O and suffered little net loss of H₂O due to shock. NWA 2737 amphibole has δD ≈ +3700‰; it absorbed Martian atmosphere‐derived heavy H in the aftermath of shock. Chassigny amphibole, with δD ≤ +1900‰, incorporated less heavy H. Low H₂O/Cl ratios are inferred for the primitive chassignite magma, which had significant effects on melting and crystallization. Volatiles released by the degassing of Martian magma were more Cl‐rich than on Earth, resulting in the high Cl content of Martian surface materials.  相似文献