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  • 1
    ISSN: 1520-510X
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-1238
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1432-1238
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 28 (1992), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Confined production of poultry results in significant volumes of waste material which are typically disposed of by land application. Concerns over the potential environmental impacts of poultry waste disposal have resulted in ongoing efforts to develop management practices which maintain high quality of water downstream of disposal areas. The timing of application to minimize waste constituent losses is a management practice with the potential to ensure high quality of streams, rivers, and lakes downstream of receiving areas. This paper describes the development and application of a method to identify which time of year is best, from the standpoint of surface water quality, for land application of poultry waste. The procedure consists of using a mathematical simulation model to estimate average nitrogen and phosphorus losses resulting from different application timings, and then identifying the timings which minimize losses of these nutrients. The procedure was applied to three locations in Arkansas, and three different criteria for optimality of application timing were investigated. One criterion was oriented strictly to water quality, one was oriented only to crop production, and the last was a combination. The criteria resulted in different windows of time being identified as optimal. Optimal windows also varied with location of the receiving area. The results indicate that it is possible to land-apply poultry waste at times which both minimize nutrient losses and maximize crop yield.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of the American Water Resources Association 30 (1994), S. 0 
    ISSN: 1752-1688
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Architecture, Civil Engineering, Surveying , Geography
    Notes: : Application of fertilizer can degrade quality of runoff, particularly during the first post-application, runoff-producing storm. This experiment assessed and compared runoff quality impacts of organic and inorganic fertilizer application for a single simulated storm occurring seven days following application. The organic fertilizers used were poultry (Gallus gallus domesticus) litter, poultry manure, and swine (Sus scrofa domesticus) manure. All fertilizers were applied at an application rate of 217.6 kg N/ha. Simulated rainfall was applied at 50 mm/h for an average duration of 0.8 h. Runoff samples were collected, composited, and analyzed for nitrate N (NO3-N), ammonia N (NH3-N), total Kjeldahl N (TKN), ortho-P (PO4-P), total P (TP), chemical oxygen demand (COD), total suspended solids (TSS), fecal coliforms (FC), and fecal streptococci (FS). Application of the fertilizers did not alter the hydrologic characteristics of the receiving plots relative to the control plots. Concentrations of fertilizer constituents were almost always greater from treated than from control plots and were usually much greater. Flow-weighted mean concentrations of NH3-N, PO4-P, and TP were highest for the inorganic fertilizer treatment (42.0, 26.6, and 27.9 mg/L, respectively). Runoff COD and TSS concentrations were greatest for the poultry litter treatment. Concentrations of FC and FS were greater for fertilized than for control plots with no differences among fertilized plots, but FC concentrations for all treatments were in excess of Arkansas' primary and secondary contact standards. Mass losses of fertilizer constituents were low (≤ 3 kg/ha) and were small proportions (≤ 3 percent) of amounts applied.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 67 (1990), S. 3121-3131 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Ion-beam mixing of tin on iron provides corrosion protection against high-temperature oxidation. Previous studies have been inconclusive as to the exact composition and distribution of alloys produced at the Fe/Sn interface. This study provides a detailed diagram of Fe-Sn specimens after ion-beam mixing with Ar+ at 40 keV and a dose of 5×1016 ions/cm2 . The interface was isotopically labeled with 7.5 nm of 57 Fe and 119 Sn so that dual perspective conversion electron Mössbauer spectroscopy could be performed. Analyses in this manner allowed comparison of 119 Sn conversion electron Mössbauer spectroscopy (CEMS) and 57 Fe CEMS spectra to accurately assign spectral components which could not be conclusively assigned using a single CEMS perspective. Information from Rutherford backscattering spectrometry confirmed the layered nature of specimens prior to implantation and was used for depth determination of the mixed region after implantation. X-ray photoelectron spectroscopy, secondary ion mass spectrometry, and scanning electron microscopy also provided information after implantation. Data indicate the formation of a uniform amorphous surface during implantation resulting in a heterogeneous mixture of components consisting mainly of dilute tin in iron (approximately 8-at. % Sn) and FeSnx (x≈1). About 80% of the 37.5-nm tin overlayer was removed by sputtering. The components identified are somewhat more iron rich than previous assignments and illustrate the difference in surface structures resulting from various implantation parameters.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : American Institute of Physics (AIP)
    Physics of Fluids 2 (1990), S. 45-55 
    ISSN: 1089-7666
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Flow fields within spatially periodic arrays of cylinders arranged in square and hexagonal lattices are calculated, with microscale Reynolds number ranging between zero and 200, employing a finite element numerical scheme. The terminology of an "apparent permeability'' is introduced to establish a relationship existing between mean velocity and macroscopic pressure gradient characterized by a finite Reynolds number flow. In contrast with the low Reynolds number "true '' permeability, the apparent permeability is shown here to generally depend upon the direction of the applied pressure gradient, owing to nonlinearities existing within the local fluid motion. The orientation-dependent permeabilities of both square and hexagonal monodisperse arrays are observed to diminish with increasing Reynolds number. Similar behavior is also observed for a bidisperse square array, though the apparent permeability of the latter is shown less sensitive to Darcy velocity orientation at large Reynolds numbers in comparison to the corresponding monodisperse square array, for all cylinder concentrations examined.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Sedimentology 41 (1994), S. 0 
    ISSN: 1365-3091
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Geosciences
    Notes: Experimental results are reported concerning the nature of reflected flows generated when density currents are incident upon ramp-type flow obstructions. The reflected flows are bores (moving hydraulic jumps that transport mass) with flow characteristics in common with either a group of solitary waves (weak Type A bores) or the original density current (strong Type C bores). Alternatively, the bore may have attributes in common with both of these end-member forms (intermediate Type B bores). Bore strength is positively correlated with the ratio of reverse flow thickness to that of the residual tail of the forward flow. The largest values of this ratio occur when ‘proximal’reflections arrive at the steeper ramps. Measured particle paths in the bores indicate that natural examples will have the potential to transport and deposit sediment. Strong bores have velocity characteristics very similar to the original current and thus in nature the generated sequence of sedimentary structures will resemble those of the original depositing current. The train of solitary waves that make up a weak bore sequence exhibits a pulsating velocity profile at a point. Such flows may thus generate repeated sequences of structures separated by fine ‘drapes’that are distinguishable from the deposits of the original turbidity current. These conclusions are applied to examples of reflected turbidites described from the Palaeozoic to Quaternary sedimentary record.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 1432-1351
    Keywords: Crayfish ; Electrical synapse ; Rectification ; Computer simulation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Summary The rectification properties of electrical synapses made by the segmental giant (SG) neurone of crayfish (Pacifastacus leniusculus) were investigated. The SG acts as an interneurone, transmitting information from the giant command fibres (GFs) to the abdominal fast flexor (FF) motoneurones. The GF-SG (input) synapses are inwardly-rectifying electrical synapses, while the SG-FF (output) synapses are outwardly rectifying electrical synapses. This implies that a single neurone can make gap junction hemichannels with different rectification properties. The coupling coefficient of these synapses is dependent upon transjunctional potential. There is a standing gradient in resting potential between the GFs, SG and FFs, with the GFs the most hyperpolarized, and the FFs the most depolarized. The gradient thus biases each synapse into the low-conductance state under resting conditions. There is functional double rectification between the bilateral pairs of SGs within a single segment, such that depolarizing membrane potential changes of either SG pass to the other SG with less attenuation than do hyperpolarizing potential changes. Computer simulation suggests that this may result from coupling through the intermediary FF neurones.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [s.l.] : Nature Publishing Group
    Nature 357 (1992), S. 683-685 
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] The specimens come from the same stream section through Lower Old Red Sandstone fluviatile sediments on Brown Clee Hill, Shropshire, that have yielded the well preseved C. pertoni2-3. Spore assemblages indicate a Gedinnian age (middle micrornatus-newportensis miospore assemblage subzone)5. The ...
    Type of Medium: Electronic Resource
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