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  • 1
    Electronic Resource
    Electronic Resource
    Post-freeze recovery of peripheral nerve function in the freeze-tolerant wood frog, Rana sylvatica (1994)
    Springer
    Journal of comparative physiology 164 (1994), S. 316-320 
    Details
    ISSN: 1432-136X
    Keywords: Freeze tolerance ; Sciatic nerve ; Osmotic stress ; Cryoprotection ; Frog, Rana sylvatica
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract We investigated the restoration of peripheral nerve function and simple neurobehavioral reflexes in the freeze-tolerant wood frog (Rana sylvatica). Thirty-two specimens, allowed to freeze for 39 h and ultimately cooled to-2.2°C, were sampled at various time intervals up to 60 h after thawing at 5°C was initiated. The sciatic nerves of treated frogs were initially unresponsive to stimulation, but usually regained excitability within 5 h. Except for a slight reduction in nerve excitability characteristics of the compound action potentials of treated frogs were indistinguishable from those of control frogs. Recovery times for the hindlimb retraction and righting reflexes were 8 h and 14 h, respectively. Concentrations of the cryoprotectant glucose increased 8.2-fold in the sciatic nerve and 10.5-fold in the underlying semimembranosis muscle of treated frogs, and remained elevated for at least 60 h after thawing was initiated. These organs lost 47.2% and 15.9%, respectively, of their water during freezing, but were rehydrated within 2 h of the onset of thawing. The accumulation of glucose and the withdrawal of tissue water apparently are cryoprotective responses which enable this species to survive freezing.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00346449
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Supercooling, ice inoculation and freeze tolerance in the European common lizard, Lacerta vivipara (1995)
    Springer
    Journal of comparative physiology 165 (1995), S. 238-244 
    Details
    ISSN: 1432-136X
    Keywords: Freeze tolerance ; Supercooling ; Cold-hardiness ; Cryoprotection ; Lizard ; Lacerta
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract The European common lizard (Lacerta vivipara) is widely distributed throughout Eurasia and is one of the few Palaearctic reptiles occurring above the Arctic Circle. We investigated the cold-hardiness of L. vivipara from France which routinely encounter subzero temperatures within their shallow hibernation burrows. In the laboratory, cold-acclimated lizards exposed to subfreezing temperatures as low as -3.5°C could remain unfrozen (supercooled) for at least 3 weeks so long as their microenvironment was dry. In contrast, specimens cooled in contact with ambient ice crystals began to freeze within several hours. However, such susceptibility to inoculative freezing was not necessarily deleterious since L. vivipara readily tolerated the freezing of its tissues, with body surface temperatures as low as -3.0°C during trials lasting up to 3 days. Freezing survival was promoted by relatively low post-nucleation cooling rates (≤0.1°C·h-1) and apparently was associated with an accumulation of the putative cryoprotectant, glucose. The cold-hardiness strategy of L. vivipara may depend on both supercooling and freeze tolerance capacities, since this combination would afford the greatest likelihood of surviving winter in its dynamic thermal and hydric microenvironment.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00260815
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    The cause and cure (?) of the spurious pressures generated by certain FEM solutions of the incompressible Navier-Stokes equations: Part 1 (1981)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 1 (1981), S. 17-43 
    Details
    ISSN: 0271-2091
    Keywords: Finite Element ; Navier-Stokes ; Incompressible Flows ; Penalty Methods ; Pressure Filters ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The spurious pressures and ostensibly acceptable velocities which sometimes result from certain FEM approximate solutions of the incompressible Navier-Stokes equations are explained in detail. The concept of pressure modes, physical and spurious, pure and impure, is introduced and their effects on discretized solutions is analysed, in the context of both mixed interpolation and penalty approaches. Pressure filtering schemes, which are capable of recovering useful pressures from otherwise polluted numerical results, are developed for two particular elements in two-dimensions and one element in three-dimensions. Implications regarding the effect of spurious pressure modes on accuracy and ultimate convergence with mesh refinement are discussed and a list of unanswered questions presented. Sufficient numerical examples are discussed to corroborate the theory presented herein.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650010104
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    The cause and cure (!) of the spurious pressures generated by certain fem solutions of the incompressible Navier-Stokes equations: Part 2 (1981)
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 1 (1981), S. 171-204 
    Details
    ISSN: 0271-2091
    Keywords: Finite Element ; Navier-Stokes ; Incompressible Flows ; Penalty Methods ; Pressure Filters ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: The spurious pressures and ostensibly acceptable velocities which sometimes result from certain FEM approximate solutions of the incompressible Navier-Stokes equations are explained in detail. The concept of pressure modes, physical and spurious, pure and impure, is introduced and their effects on discretized solutions is analysed, in the context of mixed interpolation and penalty approaches. Pressure filtering schemes, which are capable of recovering useful pressures from otherwise polluted numerical results, are developed for two particular elements in two-dimensions and one element in three-dimensions. The automatic pressure filter associated with the penalty method is also explained. Implications regarding the effect of spurious pressure modes on accuracy and ultimate convergence with mesh refinement are discussed and a list of unanswered questions presented. Sufficient numerical examples are discussed to corroborate the theory presented herein.
    Additional Material: 19 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/fld.1650010206
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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