The vibrational distribution of O₂ in the dayside ionosphere     

J. L. Fox 《Planetary and Space Science》1986,34(12):1241-1252

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The effect of calcium on aqueous uranium(VI) speciation and adsorption to ferrihydrite and quartz   总被引：2，自引：0，他引：2  

Patricia M. Fox  James A. Davis 《Geochimica et cosmochimica acta》2006,70(6):1379-1387

Recent studies of uranium(VI) geochemistry have focused on the potentially important role of the aqueous species, CaUO₂(CO₃)₃²⁻ and Ca₂UO₂(CO₃)₃⁰(aq), on inhibition of microbial reduction and uranium(VI) aqueous speciation in contaminated groundwater. However, to our knowledge, there have been no direct studies of the effects of these species on U(VI) adsorption by mineral phases. The sorption of U(VI) on quartz and ferrihydrite was investigated in NaNO₃ solutions equilibrated with either ambient air (430 ppm CO₂) or 2% CO₂ in the presence of 0, 1.8, or 8.9 mM Ca²⁺. Under conditions where the Ca₂UO₂(CO₃)₃⁰(aq) species predominates U(VI) aqueous speciation, the presence of Ca in solution lowered U(VI) adsorption on quartz from 77% in the absence of Ca to 42% and 10% at Ca concentrations of 1.8 and 8.9 mM, respectively. U(VI) adsorption to ferrihydrite decreased from 83% in the absence of Ca to 57% in the presence of 1.8 mM Ca. Surface complexation model predictions that included the formation constant for aqueous Ca₂UO₂(CO₃)₃⁰(aq) accurately simulated the effect of Ca²⁺ on U(VI) sorption onto quartz and ferrihydrite within the thermodynamic uncertainty of the stability constant value. This study confirms that Ca²⁺ can have a significant impact on the aqueous speciation of U(VI), and consequently, on the sorption and mobility of U(VI) in aquifers.  相似文献   

Spin-dependent limits from the DRIFT-IId directional dark matter detector     

E. DawJ.R. Fox  J.-L. GauvreauC. Ghag  L.J. HarmonM. Gold  E.R. LeeD. Loomba  E.H. MillerA.StJ. Murphy  S.M. PalingJ.M. Landers  M. PipeK. Pushkin  M. RobinsonD.P. Snowden-Ifft  N.J.C. SpoonerD. Walker 《Astroparticle Physics》2012,35(7):397-401

Data are presented from the DRIFT-IId detector operated in the Boulby Underground Science Facility in England. A 0.8 m³ fiducial volume, containing partial pressures of 30 Torr CS₂ and 10 Torr CF₄, was exposed for a duration of 47.4 live-time days with sufficient passive shielding to provide a neutron free environment within the detector. The nuclear recoil events seen are consistent with a remaining low-level background from the decay of radon daughters attached to the central cathode of the detector. However, charge from such events must drift across the entire width of the detector, and thus display large diffusion upon reaching the readout planes of the device. Exploiting this feature, it is shown to be possible to reject energy depositions from these Radon Progeny Recoil events while still retaining sensitivity to fiducial-volume nuclear recoil events. The response of the detector is then interpreted, using the F nuclei content of the gas, in terms of sensitivity to proton spin-dependent WIMP-nucleon interactions, displaying a minimum in sensitivity cross section at 1.8 pb for a WIMP mass of 100 GeV/c². This sensitivity was achieved without compromising the direction sensitivity of DRIFT.  相似文献   

Scientific information model for deepsea mapping and sampling     

Dawn J. Wright  Christopher G. Fox  Andra M. Bobbitt 《Marine Geodesy》2013,36(4):367-379

The Vents Program of the National Oceanic and Atmospheric Administration's Pacific Marine Environmental Laboratory is an interdisciplinary research initiative that brings together scientists from a wide range of disciplines, including geophysics, geology, physical oceanography, chemistry, and biology. Each discipline collects a variety of data types of varying structures and requiring intercomparison. The challenge of scientific information management is thus approached with a view of supporting data from multiple survey, mapping, and sampling tools and subject to multiple levels of interpretation. The ultimate objective is a system that integrates the functions of data storage, selective retrieval, display, and archiving. The results of our ongoing efforts in scientific information modeling and management have produced a relational database in which marine geological, geophysical, chemical, and biological observations can be accessed by any investigator.  相似文献   

Consolidating democracy in South Africa: the second open election     

Anthony Lemon  Roddy Fox 《Area》2000,32(3):337-344

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The evolution of Rapid Burster outbursts     

R. Guerriero    D. W. Fox    J. Kommers    W. H. G. Lewin    R. Rutledge    C. B. Moore    E. Morgan    J. Van Paradijs    M. Van der Klis    L. Bildsten  T. Dotani 《Monthly notices of the Royal Astronomical Society》1999,307(1):179-189

We describe the evolutionary progression of an outburst of the Rapid Burster. Four outbursts have been observed with the Rossi X-Ray Timing Explorer between 1996 February and 1998 May, and our observations are consistent with a standard evolution over the course of each. An outburst can be divided into two distinct phases. Phase I is dominated by type I bursts, with a strong persistent emission component; it lasts for 15–20 d. Phase II is characterized by type II bursts, which occur in a variety of patterns. The light curves of time-averaged luminosity for the outbursts show some evidence for reflares, similar to those seen in soft X-ray transients. The average recurrence time for Rapid Burster outbursts during this period was 218 d, in contrast to an average ∼180‐d recurrence period observed during 1976–1983.  相似文献   

Inversion of provenance data and sediment load into spatially varying erosion rates     

Fien De Doncker  Frédéric Herman  Matthew Fox 《地球表面变化过程与地形》2020,45(15):3879-3901

Sediment fingerprinting methods aim to determine the relative contribution of different source areas in detrital sediments based on natural properties – fingerprints – of the source areas. Here, we use U/Th–Pb age signatures as fingerprints, assuming that the age signal is not altered during erosion–transportation–deposition events, and given that recent technological advances enable precise dating of large amounts of grains. We introduce a formal inversion method that allows to disentangle the amalgamation of source contributions in detrital zircon data and enables to convert this information into an erosion rate map starting from the spatial distribution of zircon age signatures. Relying on the least-squares method and using prior and covariance information to deal with non-uniqueness, we show, using synthetic and natural examples, that we are able to retrieve erosion rate patterns of a catchment when the age distribution and zircon fertility for each source area are well known. Moreover, we show that not only zircon age fingerprints but also other tracers such as mineral content can be used. Furthermore, we found that adding data from samples taken at the outlet of tributaries improves the estimation of erosion rate patterns. We conclude that the least squares inverse model applied to detrital data has great potential for investigating erosion rates. © 2020 John Wiley & Sons, Ltd.  相似文献