Newly recognized hosts for uranium in the Hanford Site vadose zone     

Joanne E. Stubbs  Linda A. Veblen  David C. Elbert  James A. Davis 《Geochimica et cosmochimica acta》2009,73(6):1563-234

Uranium contaminated sediments from the U.S. Department of Energy’s Hanford Site have been investigated using electron microscopy. Six classes of solid hosts for uranium were identified. Preliminary sediment characterization was carried out using optical petrography, and electron microprobe analysis (EMPA) was used to locate materials that host uranium. All of the hosts are fine-grained and intergrown with other materials at spatial scales smaller than the analytical volume of the electron microprobe. A focused ion beam (FIB) was used to prepare electron-transparent specimens of each host for the transmission electron microscope (TEM). The hosts were identified as: (1) metatorbernite [Cu(UO₂)₂(PO₄)₂·8H₂O]; (2) coatings on sediment clasts comprised mainly of phyllosilicates; (3) an amorphous zirconium (oxyhydr)oxide found in clast coatings; (4) amorphous and poorly crystalline materials that line voids within basalt lithic fragments; (5) amorphous palagonite surrounding fragments of basaltic glass; and (6) Fe- and Mn-oxides. These findings demonstrate the effectiveness of combining EMPA, FIB, and TEM to identify solid-phase contaminant hosts. Furthermore, they highlight the complexity of U geochemistry in the Hanford vadose zone, and illustrate the importance of microscopic transport in controlling the fate of contaminant metals in the environment.  相似文献   

From contesting to conversing about resilience: kickstarting measurement in complex research environments     

Ivory  Vivienne C.  Stevenson  Joanne R. 《Natural Hazards》2019,96(2):935-959

Natural Hazards - Landslides are one of the most damaging disastrous phenomena that frequently lead to serious problems in hilly areas. The Namchi region of South Sikkim district as a part of...  相似文献   

Locating imaginary homelands: literature, geography, and Salman Rushdie     

Dr. Joanne P. Sharp 《GeoJournal》1996,38(1):119-127

This paper represents an exploration of the relationships between geographical and fictional literatures. In general, geographers have not made sufficient use of literary sources in their work. In this paper the author goes beyond using literary quotations to provide a feel or impression of a region or place, to regard specific texts as containing a voice which can speak to the geographies created by academics. This means that geographers can regard fictional literature as offering an alternative account of the processes that they are seeking to describe and explain. After a brief introduction to the current relationship between geography and literature, it is discussed how fiction is used as a source in other disciplines. Finally, the suggested approach to literature is applied to the work of Salman Rushdie, especially to his controversial novel The Satanic Verses.  相似文献   

The radio–optical correlation in steep-spectrum quasars     

Stephen Serjeant  Steve Rawlings  Stephen J. Maddox  Joanne C. Baker  Dave Clements  Mark Lacy  & Per B. Lilje 《Monthly notices of the Royal Astronomical Society》1998,294(3):494-504

Using complete samples of steep-spectrum quasars, we present evidence for a correlation between radio and optical luminosity which is not caused by selection effects, nor caused by an orientation dependence (such as relativistic beaming), nor a by-product of cosmic evolution. We argue that this rules out models of jet formation in which there are no parameters in common with the production of the optical continuum. This is arguably the most direct evidence to date for a close link between accretion on to a black hole and the fuelling of relativistic jets. The correlation also provides a natural explanation for the presence of aligned optical/radio structures in only the most radio-luminous high-redshift galaxies.  相似文献   

Evaluation of video and acoustic index methods for assessing reef-fish populations   总被引：1，自引：0，他引：1  

Gledhill  Christopher T.; Lyczkowski-Shultz  Joanne; Rademacher  Kevin; Kargard  Eva; Crist  Gregg; Grace  Mark A. 《ICES Journal of Marine Science》1996,53(2):483-485

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Benchmarking sustainability in cities: The role of indicators and future scenarios     

Christopher T. Boyko  Mark R. Gaterell  Austin R.G. Barber  Julie Brown  John R. Bryson  David Butler  Silvio Caputo  Maria Caserio  Richard Coles  Rachel Cooper  Gemma Davies  Raziyeh Farmani  James Hale  A. Chantal Hales  C. Nicholas Hewitt  Dexter V.L. Hunt  Lubo Jankovic  Ian Jefferson  Joanne M. Leach  D. Rachel Lombardi  Christopher D.F. Rogers 《Global Environmental Change》2012,22(1):245-254

Scenarios are a useful tool to help think about and visualise the future and, as such, are utilised by many policymakers and practitioners. Future scenarios have not been used to explore the urban context in much depth, yet have the potential to provide valuable insights into the robustness of decisions being made today in the name of sustainability. As part of a major research project entitled Urban Futures, a toolkit has been developed in the UK to facilitate the use of scenarios in any urban context and at any scale relevant to that context. The toolkit comprises two key components, namely, (i) a series of indicators comprising both generic and topic area-specific indicators (e.g., air quality, biodiversity, density, water) that measure sustainability performance and (ii) a list of characteristics (i.e., 1–2-sentence statements about a feature, issue or small set of issues) that describe four future scenarios. In combination, these two components enable us to measure the performance of any given sustainability indicator, and establish the relative sensitivity or vulnerability of that indicator to the different future scenarios. An important aspect of the methodology underpinning the toolkit is that it is flexible enough to incorporate new scenarios, characteristics and indicators, thereby allowing the long-term performance of our urban environments to be considered in the broadest possible sense.  相似文献   

Imaging X-ray Polarimeter for Solar Flares (IXPS)     

Michael Hosack  J. Kevin Black  Philip Deines-Jones  Brian R. Dennis  Joanne E. Hill  Keith Jahoda  Albert Y. Shih  Christian E. Urba  A. Gordon Emslie 《Experimental Astronomy》2011,32(2):101-125

We describe the design of a balloon-borne Imaging X-ray Polarimeter for Solar flares (IXPS). This novel instrument, a Time Projection Chamber (TPC) for photoelectric polarimetry, will be capable of measuring polarization at the few percent level in the 20?C50 keV energy range during an M- or X-class flare, and will provide imaging information at the ??10 arcsec level. The primary objective of such observations is to determine the directivity of nonthermal high-energy electrons producing solar hard X-rays, and hence to learn about the particle acceleration and energy release processes in solar flares. Secondary objectives include the separation of the thermal and nonthermal components of the flare X-ray emissions and the separation of photospheric albedo fluxes from direct emissions.  相似文献   

Geochemical gradients and artifact mass densities on the lowermost Bed II eastern lake margin (~ 1.8 Ma), Olduvai Gorge, Tanzania     

Daniel M. Deocampo  Joanne C. Tactikos 《Quaternary Research》2010,74(3):411-423

Bulk geochemistry of ~ 1.8 Ma lacustrine claystone at Olduvai Gorge, Tanzania, is controlled principally by the geochemistry of ultrafine (< 0.1 μm), authigenic clay minerals. Authigenic clays have an average structural formula of (Si_3.83Al_0.17)(Al_0.43Fe_0.49Mg_0.84)(Na_0.99K_0.22Ca_0.16)O₁₀(OH)₂; octahedral composition varies, with Mg/(Al + Fe) ranging from 0.7 to 2.3. These clay minerals have a complex history of interaction with saline, alkaline water, followed by secondary diagenetic reactions that leached Mg in freshwater paleoenvironments. Lateral variations in whole-rock and clay geochemistry show westward enrichment in Mg, from Mg_oct = 0.6–1.6. This is consistent with persistence of saline, alkaline Paleolake Olduvai to the west, and the presence of groundwater wetlands and other freshwater paleoenvironments to the east. Stone artifact mass density also varies systematically across the basal Bed II deposits, ranging from 10^0.0 to 10^4.3 g of artifacts per cubic meter of excavated sediment. Significant correlation is found between clay geochemistry and the density of artifacts excavated from associated archeological trenches (r² = 0.59, p < 0.01). This relationship supports models of hominin land use in which artifact use and discard is concentrated near freshwater paleoenvironments such as wetlands associated with surface and groundwater discharge. Independent paleoenvironmental proxies such as clay geochemistry allow quantitative hypothesis testing to improve our understanding of early hominin behavior and paleoecology.  相似文献   

Vertical Distribution and Migration of Decapod Larvae in Relation to Light and Tides in Willapa Bay,Washington     

Joanne K. Breckenridge  Stephen M. Bollens 《Estuaries and Coasts》2011,34(6):1255-1261

We investigated the occurrence of behaviors that maximize predator avoidance and seaward transport in estuarine decapod zoeae by collecting larvae from discrete depths in a partially mixed estuary, Willapa Bay, Washington, USA, and relating their abundance and vertical distribution to a suite of environmental variables. Abundances of first zoeae of Neotrypaea californiensis and Pinnotheridae were associated with tidal phase, diel phase, and water height. Both taxa were most abundant during ebb tides, and abundances increased with water height, suggesting behaviors that enhanced seaward transport. Additionally, N. californiensis were both shallower and more abundant at night, indicative of behaviors to avoid visual predators. Our results suggest that both tidal transport and predator avoidance are important and sometimes interactive selective forces shaping larval decapod behavior.  相似文献   

A subaltern critical geopolitics of the war on terror: Postcolonial security in Tanzania   总被引：1，自引：0，他引：1  

Joanne Sharp 《Geoforum》2011,42(3):297-305

Currently, hegemonic geographical imaginations are dominated by the affective geopolitics of the War on Terror, and related security practice is universalised into what has been called “globalized fear” (Pain, 2009). Critical approaches to geopolitics have been attentive to the Westerncentric nature of this imaginary, however, studies of non-Western perceptions of current geopolitics and the nature of fear will help to further displace dominant geopolitical imaginations. Africa, for example, is a continent that is often captured in Western geopolitics - as a site of failed states, the coming anarchy, passive recipient of aid, and so on - but geopolitical representations originating in Africa rarely make much of an impact on political theory.This paper aims to add to critical work on the so-called War on Terror from a perspective emerging from the margins of the dominant geopolitical imagination. It considers the geopolitical imagination of the War on Terror from a non-Western source, newspapers in Tanzania.  相似文献