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  • 2000-2004  (2)
  • 1985-1989  (2)
  • 1910-1914
  • 1890-1899
  • 2002  (2)
  • 1985  (2)
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  • 2000-2004  (2)
  • 1985-1989  (2)
  • 1910-1914
  • 1890-1899
Year
  • 1
    ISSN: 1365-3040
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: Differently oriented leaves of Yucca schidigera and Yucca brevifolia were characterized in the Mojave Desert with respect to photosystem II and xanthophyll cycle activity during three different seasons, including the hot and dry summer, the relatively cold winter, and the mild spring season. Photosynthetic utilization of a high percentage of the light absorbed in PSII was observed in all leaves only during the spring, whereas very high levels of photoprotective, thermal energy dissipation were employed both in the summer and the winter season in all exposed leaves of both species. Both during the summer and the winter season, when energy dissipation levels were high diurnally, xanthophyll cycle pools (relative to either Chl or other carotenoids) were higher relative to the spring, and a nocturnal retention of high levels of zeaxanthin and antheraxanthin (Z + A) occurred in all exposed leaves of both species. Although this nocturnal retention of Z + A was associated with nocturnal maintenance of a low PSII efficiency (Fv/Fm) on a cold winter night, pre-dawn Fv/Fm was high in (Z + A)-retaining leaves following a warm summer night. This indicates nocturnal engagement of Z + A in a state primed for energy dissipation throughout the cold winter night – while high levels of retained Z + A were not engaged for energy dissipation prior to sunrise on a warm summer morning. Possible mechanisms for a lack of sustained engagement of retained Z + A for energy dissipation at elevated temperatures are discussed.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1365-2761
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology , Medicine
    Notes: Winter flounder, Pseudopleuronectes americanus, caught in Passamaquoddy Bay, New Brunswick, Canada, and held captive under crowded conditions, developed mixed infections of Trichodina murmanica Polyanski, 1955 (Ciliophora) and Gyrodactylus pleuronecti Cone, 1981 (Monogenea). A protocol involving sequential sieving was used to separate the two species of parasites and produce viable experimental baths. Replicate groups of juvenile, hatchery-reared flounder received one of the following treatments: mixed bath of G. pleuronecti and T. murmanica, bath of G. pleuronecti, bath of T. murmanica or parasite-free (controls). The abundance of both parasites correlated negatively with condition factor of the flounder (r=−0.354, P 〈 0.001 for Trichodina; r=–0.205, P 〈 0.05 for Gyrodactylus). During the periods of peak parasite abundance (1–2 weeks postinfection), the effect of the two parasite species was additive, as mean condition factor and the percentage change in weight were significantly lower (ANOVA, P 〈 0.05) among fish with mixed infections compared to single infections or controls. The most common signs of tissue pathology were increased density of epidermal mucous cells on the fins and macrovesicular lipidosis of the hepatocytes. After a significant decline in parasite infrapopulations (3 weeks postinfection), infected fish resumed normal growth, indicating the observed effects were somewhat reversible.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 25 (1985), S. 344-353 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract The mixed-mode, elastodynamic state of stress in the neighborhood of a constant-velocity crack tip is used to generate numerically unsymmetric isochromatics. Unsymmetry associated with the third-order terms of a mixed-mode stress field, with and without the Mode II singular stress term, is also investigated. In extractingK I from an unsymmetric isochromatic pattern, errors in the Mode I fracture parameters due to the assumed presence ofK II in aK I stress field were found to be significant when data are taken more than 4 mm from the crack tip.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Experimental mechanics 25 (1985), S. 399-407 
    ISSN: 1741-2765
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract A general algorithm is presented that computes the stress-field parameters for opening-mode crack problems in a least-squares sense from full-field moiré or speckle-displacement fringe patterns. The algorithm can be used in the presence of rigid-body rotation and does not require absolute fringe numbering. Extensive numerical experiments were conducted with the algorithm to determine the sensitivity of the method to experimental errors. Small random position errors in locating the fringe maxima were found to have a negligible influence on the stress-intensity-factor calculation when the number of data points was about ten times greater than the number of unknown stress-field parameters. It was also found that systematic position errors due to an incorrectly specified crack-tip location could be minimized by assuming various crack-tip locations in the vicinity of the actual crack tip and selecting the best fit results. Bothu andv fields were found to be equally suitable for determination of the stress-intensity factor.
    Type of Medium: Electronic Resource
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