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  • Stratification  (2)
  • Estuarine processes  (1)
  • Immunization  (1)
  • American Geophysical Union  (3)
  • Springer  (1)
  • American Geophysical Union (AGU)
  • American Meteorological Society (AMS)
  • 2010-2014  (3)
  • 2005-2009
  • 1980-1984  (1)
  • 1930-1934
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Publisher
  • American Geophysical Union  (3)
  • Springer  (1)
  • American Geophysical Union (AGU)
  • American Meteorological Society (AMS)
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  • 2010-2014  (3)
  • 2005-2009
  • 1980-1984  (1)
  • 1930-1934
  • 2015-2019  (1)
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  • 1
    ISSN: 1432-1955
    Keywords: Capillaria hepatica ; X-ray attenuation ; Immunization ; Capillaria hepatica ; Röntgenstrahlenaltenuierung ; Immunisierung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Description / Table of Contents: Zusammenfassung Der Einfluß von Erstinfektionen mit embryonierten Eiern, von röntgenattenuierten Stadien, von nicht embryonierten Eiern und löslichen Eiextrakten auf Belastungsinfektionen mitCapillaria hepatica wurde untersucht. Die Reproduktivität einer Wurmpopulation aus einer subletalen Belastungsinfektion wurde inMastomys natalensis durch eine 11 Tage vorher gesetzte Erstinfektion mit 50, 150, 400 oder 800 embryonierten Eiern/Tier signifikant reduziert. Ein signifikanter Einfluß von röntgenattenuierten, infektiösen Eiern bzw. von intraperitoneal injizierten, nicht embryonierten Eiern (bei steigenden Dosen über 10 Tage wurde die Eiproduktion normaler Infektionen simuliert) beschränkte sich auf schwache (50 Eier/Tier) Belasnungsinfektionen. Die Kombination attenuierten Infektionsmaterials mit nicht embryonierten Eiern i.p. führte zu keiner gesteigerten Wirkung. In Albinomäusen ließ sich durch vorherige, wiederholte subkutane Injektion von löslichen Eiextrakten die Eiproduktion einer mittleren Belastungsinfektion bis zum 60. Tag p.i. hochsignifikant reduzieren. Die durch Infektionsdosen von 230 embryonierten Eiern/g Körpergewicht beiM. natalensis zwischen dem 20. und 35. Tag p.i. 100% erreichende Mortalität ließ sich durch vorherige Applikation von 50, 150, 400 und 800 Eiern/Tier bei nach 36 und 52 Tagen gesetzten Belastungsinfektionen auf 0–30% reduzieren. Bei Verwendung attenuierten Infektionsmaterials war für einen 70–80% igen Schutz eine wiederholte Vakzinierung notwendig. Die intraperitoneale Injektion von nicht embryonierten Eiern führte bei 40% der Tiere zu einem Schutz. Der Eintritt des Todes verzögerte sich i.d.R. bei vorbehandelten Tieren.
    Notes: Abstract The influence of primary infections with embryonated infective eggs or with X-irradiated infective eggs, and of non-embryonated eggs, and egg homogenate extracts on challenge infections withCapillaria hepatica was investigated. The worm reproductivity was significantly suppressed in a sublethal challenge infection given 11 days after a primary infection ofMastomys natalensis with 50, 150, 400, and 800 eggs per animal. The administration of 600 X-irradiated (2.2 Krd) embryonated eggs 36 days before challenge as well as an intraperitoneal injection of non-embryonated eggs 12, 10, 8, 6, 4, and 2 days before challenge (simulating the egg production of a normal infection) also reduced significantly the egg production of a weak (50 eggs/animal) infection. No effect was observed on a moderate challenge (300 eggs/animal). The effect was not markedly enhanced by the repeated administration of X-irradiated eggs or by the combination of X-irradiated infective eggs and non-embryonated eggs. Immunization of mice with soluble egg extracts resulted in significant reduction of egg production determined 60 days after challenge. Two hundred and thirty eggs ofC. hepatica/g bodyweight proved to be a lethal infection dose forM. natalensis. The animals died between 20 and 35 days after infection. After single infections with 50, 150, 400, or 800 eggs per animal the mortality ofMastomys challenged 36 or 52 days later was reduced to 0–30%. Using X-irradiated embryonated eggs for immunization only repeated administration led to protection in 70 to 80% of the animals. About 40% of the animals could be protected by the intraperitoneal injection of non-embryonated eggs. If death occurred it was delayed. The combination of X-irradiated stages and eggs did not enhance the protection.
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  • 2
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2004. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 109 (2004): F02004, doi:10.1029/2003JF000096.
    Description: A 9 month time series of tripod-mounted optical and acoustic measurements of sediment concentration and bed elevation was used to examine depositional processes in relationship to hydrodynamic variables in the Hudson River estuary. A series of cores was also taken directly under and adjacent to the acoustic measurements to examine the relation between the depositional processes and the resulting fine-scale stratigraphy. The measurements reveal that deposition occurs as a result of sediment flux convergence behind a salinity front and that the accumulation rates are sufficient to deposit up to 25 cm of new high-porosity sediment in a single ebb-tidal phase. Subsequent dewatering and erosion reduces the thickness of the initial deposit to several centimeters. These depositional events were only observed on spring tides. Ten depositional events during two spring tidal cycles produced a seasonal deposit of 18 cm, consistent with estimates of seasonal deposition from cores. A proxy for near-bed suspended grain size variations was estimated from the combined acoustic and optical measurements, implying that the erosional processes resuspend only the finer-grained sediments, thus leaving behind silt and very fine grained sand beds. The thickness of the deposited homogenous clayey silt beds, and the vertical separation between beds interlaminated with silt and very fine sand, are roughly consistent with the acoustic measurements of changes in bed elevations during deposition and erosion. The variability in individual bed thickness is the result of variations of processes over an individual tidal cycle and is not a product of variations over the spring neap fortnightly timescale.
    Description: The authors would like to acknowledge the Hudson River Foundation, who provided funding for this work under grant 009/00A.
    Keywords: Sediment transport ; Estuarine processes ; Fluid mud
    Repository Name: Woods Hole Open Access Server
    Type: Article
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  • 3
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2010. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 37 (2010): L22607, doi:10.1029/2010GL045272.
    Description: Shear instability is the dominant mechanism for converting fluid motion to mixing in the stratified ocean and atmosphere. The transition to turbulence has been well characterized in laboratory settings and numerical simulations at moderate Reynolds number—it involves “rolling up”, i.e., overturning of the density structure within the cores of the instabilities. In contrast, measurements in an energetic estuarine shear zone reveal that the mixing induced by shear instability at high Reynolds number does not primarily occur by overturning in the cores; rather it results from secondary shear instabilities within the zones of intensified shear separating the cores. This regime is not likely to be observed in the relatively low Reynolds number flows of the laboratory or in direct numerical simulations, but it is likely a common occurrence in the ocean and atmosphere.
    Description: This research was supported by NSF grant OCE‐0824871 and ONR grant N00014‐0810495.
    Keywords: Stratification ; Turbulence ; Mixing
    Repository Name: Woods Hole Open Access Server
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  • 4
    Publication Date: 2022-05-25
    Description: Author Posting. © American Geophysical Union, 2012. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Journal of Geophysical Research 117 (2012): C10013, doi:10.1029/2012JC008124.
    Description: Analyses of field observations and numerical model results have identified that sediment transport in the Hudson River estuary is laterally segregated between channel and shoals, features frontal trapping at multiple locations along the estuary, and varies significantly over the spring-neap tidal cycle. Lateral gradients in depth, and therefore baroclinic pressure gradient and stratification, control the lateral distribution of sediment transport. Within the saline estuary, sediment fluxes are strongly landward in the channel and seaward on the shoals. At multiple locations, bottom salinity fronts form at bathymetric transitions in width or depth. Sediment convergences near the fronts create local maxima in suspended-sediment concentration and deposition, providing a general mechanism for creation of secondary estuarine turbidity maxima at bathymetric transitions. The lateral bathymetry also affects the spring-neap cycle of sediment suspension and deposition. In regions with broad, shallow shoals, the shoals are erosional and the channel is depositional during neap tides, with the opposite pattern during spring tides. Narrower, deeper shoals are depositional during neaps and erosional during springs. In each case, the lateral transfer is from regions of higher to lower bed stress, and depends on the elevation of the pycnocline relative to the bed. Collectively, the results indicate that lateral and along-channel gradients in bathymetry and thus stratification, bed stress, and sediment flux lead to an unsteady, heterogeneous distribution of sediment transport and trapping along the estuary rather than trapping solely at a turbidity maximum at the limit of the salinity intrusion.
    Description: This research was funded by a grant from the Hudson River Foundation (#002/07A). D.R. was partially supported by the Office of Naval Research (N00014-08-1-0846).
    Description: 2013-04-17
    Keywords: Estuarine turbidity maximum ; Lateral sediment distribution ; Salinity fronts ; Sediment flux ; Sediment trapping ; Stratification
    Repository Name: Woods Hole Open Access Server
    Type: Article
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