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  • Articles  (47)
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  • 1
    facet.materialart.
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    In:  http://aquaticcommons.org/id/eprint/1610 | 3 | 2011-09-29 20:18:05 | 1610 | Aquatic Plant Management Society, Inc.
    Publication Date: 2021-07-09
    Description: A study was conducted on a small pond in southeast Texasto evaluate the potential for using remote sensing technologyto assess feeding damage on giant salvinia (Salvinia molestaMitchell) by the salvinia weevil (Cyrtobagous salviniaeCalderand Sands). Field spectral measurements showed that moderatelydamaged and severely damaged plants had lower visibleand near-infrared reflectance values than healthy plants.Healthy, moderately damaged, and severely damaged giantsalvinia plants could be differentiated in an aerial color-infraredphotograph of the study site. Computer analysis of thephotograph showed that the three damage level classescould be quantified. (PDF has 5 pages.)
    Keywords: Management ; Biology ; Limnology ; light reflectance ; color-infrared photography ; Salvinia molesta ; Cyrtobagous salviniae ; biocontrol ; lakes ; Texas ; Bridge City
    Repository Name: AquaDocs
    Type: article , TRUE
    Format: application/pdf
    Format: application/pdf
    Format: 76-80
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 6 (1988), S. 335-343 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A specially adapted schlieren system is used to generate fluctuating signals which respond strongly to large scale coherent components of a turbulent mixing jet flow and which have a relatively reduced response to random disturbances. The schlieren signals also provide a direct indication of the presence of vortex-like structures in the turbulent mixing layers by virtue of the phase relationship of the schlieren signals to the pressure field. This system gives a clear resolution of the fluctuating periodic effects associated with vortex structures in the flow from a choked convergent nozzle. It has thus been possible to determine that vortex-like eddies are associated with the feedback screech mechanism, and also generate periodic disturbances due to their passage through the diamond shaped wave structure in the flow. The regular disturbances in the flow move at 0.77 of the fully expanded flow velocity. Phase spectral observations demonstrate clearly the vortex like structure of coherent disturbances in the flow by virtue of the quadrature phase relation between the schlieren and microphone signals. Movement of the sensing microphone in the pressure field external to the flow shows disturbance propagation at the acoustic velocity, and also shows that disturbances at Strouhal numbers above 0.7 emanating from the inner mixing zone can be identified by an additional time delay to reach the microphone and only influence the microphone when it is located downstream of the flow sensing schlieren system due to confinement of pressure disturbances within Mach cones of the flow.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 21 (1996), S. 37-42 
    ISSN: 1432-0789
    Keywords: 31P nuclear magnetic resonance (NMR) ; Soil phosphorus fractions ; Mineralization ; Tussock grassland ; Conifers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract We examined the effects of conifers on the forms of P in low-fertility tussock grassland soils using 31P nuclear magnetic resonance (NMR) and soil P fractionation. Results from field and glasshouse experiments clearly demonstrated that conifers enhanced the mineralization of labile (and to a lesser extent more resistant) forms of soil organic P which, in turn, increased amounts of labile inorganic P in the soil. These findings have important implications for P availability and long-term sustainable management of grassland soils in New Zealand.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1476-4687
    Source: Nature Archives 1869 - 2009
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
    Notes: [Auszug] Over the past decade, our physical understanding of γ-ray bursts (GRBs) has progressed rapidly, thanks to the discovery and observation of their long-lived afterglow emission. Long-duration (≳2 s) GRBs are associated with the explosive deaths of massive stars ...
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    Experiments in fluids 21 (1996), S. 248-258 
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The evaluation of fractal dimension values from schlieren flow images has been investigated. It was found for passive mixing heated jet flows that a value of 2.31, close to that obtained by tomographic imaging, was obtained. For turbulent diffusion flames a value of 2.40 was obtained, and this increased slightly with axial movement and with acoustic excitation of the flame. Broadly counteracting effects due to the transverse differentiation and integration along the imaging beam inherent in the schlieren method was found to arise.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Methods in cell science 17 (1995), S. 41-46 
    ISSN: 1573-0603
    Keywords: Bovine ; Cell culture ; Endothelial ; Mammary
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The isolation and maintenance in culture of bovine mammary gland endothelial cells is described. The uptake of acetylated low density lipoprotein labeled with 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate was used to purify the endothelial cells by fluorescence-activated cell sorting. The morphology of the purified cells is similar to that of endothelial cells from other species. The isolation of bovine mammary endothelial cells is potentially significant to study the role of the endothelium during inflammatory responses.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 126 (1990), S. 237-246 
    ISSN: 1573-5036
    Keywords: Al3+ ; Ca2+ ; Mg2+ ; NH4 + ; NO3 − ; SO4 2− ; Al toxicity ; forest dieback ; Fagus sylvatica ; Nothofagus ; pH ; Picea abies ; soil solution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Concentrations of ions were measured in soil solutions from beech (Nothofagus) forests in remote areas of New Zealand and in solutions from beech (Fagus sylvatica) and Norway spruce (Picea abies) forests in North-East Bavaria, West Germany, to compare the chemistry of soil solutions which are unaffected by acid deposition (New Zealand) with those that are affected (West Germany). In New Zealand, soil solution SO4 2− concentrations ranged between 〈2 and 58 μmol L−1, and NO3 − concentrations ranged between 〈1 and 3 μmol L−1. In West Germany, SO4 2− concentrations ranged between 80 and 700 μmol L−1, and NO3 − concentrations at three of six sites ranged between 39 and 3750 μmol L−1, but was not detected at the remaining three sites. At all sites in New Zealand, and at sites where the soil base status was moderately high in West Germany, pH levels increased, and total Al (Alt) and inorganic monomeric Al (Ali) levels decreased rapidly with increasing soil depth. In contrast, at sites on soils of low base status in West Germany, pH levels increased only slightly, and Al levels did not decline with increasing soil depth. Under a high-elevation Norway spruce stand showing severe Mg deficiency and dieback symptoms in West Germany, soil solution Mg2+ levels ranged between 20 and 60 μmol L−, and were only half those under a healthy stand. Alt and Ali levels were substantially higher the healthy stand than under the unhealthy stand, indicating that Al toxicity was not the main cause of spruce decline.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 133 (1991), S. 17-30 
    ISSN: 1573-5036
    Keywords: fertilisers ; foliage analysis ; growth studies ; Lotus ; Lupinus ; nitrogen ; nutrients ; phosphorus ; Trifolium
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The phosphorus (P) responses of seven temperate perennial pasture legumes and two species of lupins were compared in a field trial over a range of nine P rates, from 0 to 800 kg ha-1. The two lupins produced more than 5 t ha-1 of dry matter in the absence of added P and showed no response to the fertiliser. In contrast, the pasture legumes initially failed to grow without added P and responded to applications of between 200 and 800 kg ha-1. At the higher rates of P, dry matter production of the pasture legumes was equivalent to that of the lupins. In the first 2 years of the trial; the most productive pasture legume species at the higher rates of added P were also the most productive at the lower rates. Phosphorus requirements for 90% of maximum yield varied greatly between species, but were closely related to maximum yield. Thus species with low P requirements for maximum yield were not necessarily P-efficient species. In the third and subsequent years of the trial Lotus corniculatus performed better than the other pasture legumes at the lower rates of added P. In contrast to other studies Lotus pedunculatus showed no ability to outyield Trifolium repens at low rates of P. Critical P concentrations of the pasture species for the late spring-early summer period declined in the order Trifolium repens (0.34%) 〉 Lotus pedunculatus (0.30%) 〉 Triofolium pratense (0.28%) 〉 Trifolium hybridum (0.27%) 〉 Trifolium ambiguum (0.26%) 〉 Lotus corniculatus (0.23%). Mineralisable nitrogen (N) levels were determined in soils under three species in the 7th year of the trial. At the lowest rates of added P, mineralisable N levels were much higher under Lupinus polyphyllus than under Trifolium repens or Lotus corniculatus. With increasing P rate, levels under the latter species increased, and at 100 kg P ha-1 were equivalent to those under the lupin with no added P.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Plant and soil 176 (1995), S. 255-262 
    ISSN: 1573-5036
    Keywords: carbon ; cocksfoot grass ; mineralisation ; nitrogen ; phosphorus ; radiata pine ; sulphur
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Radiata pine (Pinus radiata) and cocksfoot grass (Dactylis glomerata) were grown in small pots containing grassland soils collected from seven sites in the South Island montane zone. After one year the overall mean dry matter yield of pine exceeded that of grass by a factor of 2.6, and uptake of all nutrients by pine was substantially greater. Mean soil pH was 0.3 units lower after pine growth than after grass. Organic carbon (C), total nitrogen (N), and organic phosphorus (P) levels were 15–19% lower after pine, while total P was 7% lower. Despite greater nutrient uptake by pine, mean mineralisable N and sulphate sulphur (S) levels in the soil were 500% and 200% higher respectively after pine growth than after grass. Inorganic and Bray-2 P levels were 10% and 20% higher respectively. Grass obtained almost all of its P from the inorganic pool, while pine obtained P from both inorganic and organic pools, though mostly from the latter. It is concluded that the differences observed in C, N, and P concentrations in soil indicate higher rates of mineralisation of soil organic matter in the presence of radiata pine than in the presence of cocksfoot grass. Possible implications for pastoral hill land use in New Zealand are discussed. It is suggested that pines incorporated into farming systems either on a rotational basis, or in wide-spaced agroforestry regimes, may be able to increase the rate of mineralisation of organic P, and also of N and S, and increase their availability to pasture species.
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  • 10
    ISSN: 1573-5036
    Keywords: afforestation ; soil phosphorus ; soil microbial biomass
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Selected chemical, biochemical and biological properties of mineral soil (0–30 cm) were measured under a 19 year old forest stand (mixture of Pinus ponderosa and Pinus nigra) and adjacent unimproved grassland at a site in South Island, New Zealand. The effects of afforestation on soil properties were confined to the 0–10 cm layer, which reflected the distribution of fine roots (〈 2 mm) in the soil profile. Concentrations of organic C, total N and P and all organic forms of P were lower under the forest stand, while concentrations of inorganic P were higher under forest compared with grassland, supporting the previously described suggestion that afforestation may promote mineralisation of soil organic matter and organic P. On the other hand, microbial biomass C and P, soil respiration and phosphatase enzyme activity were currently all lower and the metabolic quotient was higher in soil under forest compared with grassland, which is inconsistent with increased mineralisation in the forest soil. Reduced biological fertility by afforestation may be mainly attributed to changes in the quantity, quality and distribution of organic matter, and reduction in pH of the forest soil compared with the grassland soil. We hypothesize that the lower levels of C, N and organic P found in soil under forest are due to enhanced microbial and phosphatase activity during the earlier stages of forest development. Forest floor material (L and F layer) contained large amounts of C, N and P, together with high levels of microbial and phosphatase enzyme activity. Thus, the forest floor may be an important source of nutrients for plant growth and balance the apparent reduction in C, N and P in mineral soil through mineralisation and plant uptake.
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