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  • 1
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Ground water 30 (1992), S. 0 
    ISSN: 1745-6584
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Energy, Environment Protection, Nuclear Power Engineering , Geosciences
    Notes: A ground-water flow and contaminant transport modeling study was performed at a proposed low-level radioactive waste disposal site on the Department of Energy's Oak Ridge Reservation to assess the accuracy of a computer simulation of the flow field in the shallow water-table aquifer. The migration of a ground-water tracer, under controlled field conditions, was used as a comparative benchmark of solute transport simulations assuming different aquifer characteristics. A conventional approach to aquifer analysis and modeling, which assumed the domain to be homogeneous with low anisotropy, resulted in an inaccurate simulation of tracer migration. Alternative conceptual models were formulated which considered the effects of geologic heterogeneities on tracer migration which could be verified by additional data acquisition and analysis. Application of the alternative concepts in numerical modeling resulted in more accurate simulations of tracer migration. These results suggested that local geology created discrete flow pathways oriented oblique to the maximum gradient which were unresolved in conventional aquifer analysis. Results of the study showed that standard approaches to aquifer analysis and computer modeling are crudely representative of the flow field and provide nonconservative estimates of contaminant transport at the scale of a waste disposal unit. By adopting an iterative approach to site characterization, conceptual model formulation, and numerical modeling, the level of resolution provided by a ground-water tracer was accurately simulated.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 250 (1974), S. 44-47 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] We have used the resonance at a 19F energy of 16.45 MeV (0.83 MeV centre-of-mass energy) (ref. 4) in the nuclear reaction 1H(19F,a g)16O to measure directly the hydration profiles of obsidian samples. This technique has already been used to measure the hydrogen concentration profiles in lunar ...
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Environmental geology 21 (1993), S. 212-214 
    ISSN: 1432-0495
    Keywords: Hydropower development ; Slope stability ; Landslides sedimentation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract Two environmental assessments considered the potential cumulative environmental impacts resulting from the development of eight proposed hydropower projects in the Nooksack River Basin and 11 proposed projects in the Skagit River Basin, North Cascades, Washington, respectively. While not identified as a target resource, slope stability and the alteration of sediment supply to creeks and river mainstems significantly affect other resources. The slope stability assessment emphasized the potential for cumulative impacts under disturbed conditions (e.g., road construction and timber harvesting) and a landslide-induced pipeline rupture scenario. In the case of smallscale slides, the sluicing action of ruptured pipeline water on the fresh landslide scarp was found to be capable of eroding significantly more material than the original landslide. For large-scale landslides, sluiced material was found to be a small increment of the original landslide. These results predicted that hypothetical accidental pipeline rupture by small-scale landslides may result in potential cumulative impacts for 12 of the 19 projects with pending license applications in both river basins.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-1920
    Keywords: Key words Progressive multifocal leukoencephalopathy ; Acquired immunodeficiency syndrome ; Single-photon emission ; tomography ; Magnetic resonance imaging
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We describe a patient with AIDS who presented with focal neurological symptoms, and who had contrast-enhancing brain lesions on MRI which demonstrated increased thallium-201 uptake on SPECT. These findings were consistent with lymphoma; however, brain biopsy established a diagnosis of progressive multifocal leukoencephalopathy (PML). To our knowledge, this is the first reported case of PML with increased thallium-201 uptake on brain SPECT.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-1920
    Keywords: Key words Brain ; neoplasms ; Human Immunodeficiency Virus ; Leiomyosarcoma
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract We report an intracranial leiomyosarcoma in the pontine cistern of a 34-year-old woman infected with the human immunodeficiency virus (HIV). The clinical, radiological and pathological data are reviewed. The tumor was Epstein-Barr virus (EBV) positive by in situ hybridization. This case emphasizes that smooth muscle neoplasms arising in the setting of immunocompromise can occur intracranially, and corroborates a hypothesis that EBV coinfection may have a role in development of these tumors.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Journal of materials science 24 (1989), S. 124-132 
    ISSN: 1573-4803
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract During TEM observation, a tetragonal (t) to orthorhombic (o) phase transformation often occurs in thin portions of ZrO2-containing foils. This transformation is stress-induced and in some senses artefactual, in that the reaction product is actually a high-pressure phase, relative to monoclinic (m) ZrO2, that can form from metastable t-ZrO2 in the TEM because its density is intermediate between t- and m-ZrO2. Examples of the formation of o-ZrO2 in a number of different systems are given.
    Type of Medium: Electronic Resource
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