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  • 1
    Electronic Resource
    Electronic Resource
    Quasilinear Dirichlet problems driven by positive sources (1973)
    Springer
    Archive for rational mechanics and analysis 49 (1973), S. 241-269 
    Details
    ISSN: 1432-0673
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00250508
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  • 2
    Electronic Resource
    Electronic Resource
    Parathyroid Hormone (1-34) Receptor-Binding and Second-Messenger Response in Rat Incisor Odontoblasts (1998)
    Springer
    Calcified tissue international 62 (1998), S. 255-259 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Alkaline phosphatase — Dentinogenesis — Odontoblasts — Parathyroid hormones — Rats — Second messenger systems.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Even though indirect evidence indicates that PTH exerts an anabolic effect on dentinogenesis, the existence of PTH receptors and any second-messenger response in odontoblasts have not been demonstrated. The aim of this study was to investigate whether rat incisor odontoblasts express PTH receptors, and to identify which second messenger pathway the hormone may activate. Odontoblasts were dissected from rat incisors. Amino-terminal (1-34) fragment rat PTH [rPTH(1-34)] conjugated to fluorescein isothiocyanate visualized receptor sites on the cell surface. Upon incubation of odontoblasts with rPTH(1-34), cAMP formation was increased. However, no fluctuations in intracellular calcium activity were observed upon rPTH(1-34) stimulation when using Fura-2 as a Ca2+ probe. In long-time incubations, stimulation with PTH(1-34) upregulated APase activity. The results demonstrate that rPTH(1-34) evokes an anabolic response in dentinogenically active odontoblasts, and that this may be mediated through the protein kinase A/cAMP pathway, whereas no indications for Ca2+ as a second messenger were evident.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900426
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  • 3
    Electronic Resource
    Electronic Resource
    Voltage-Gated Calcium Channels and Nonvoltage-Gated Calcium Uptake Pathways in the Rat Incisor Odontoblast Plasma Membrane (1997)
    Springer
    Calcified tissue international 60 (1997), S. 79 -85 
    Details
    ISSN: 1432-0827
    Keywords: Key words: Ion channel gating — Voltage-gated Ca2+ channels — Agonist-sensitive Ca2+ uptake pathways — Odontoblasts — Dentinogenesis.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Notes: Abstract. Odontoblasts participate actively in the transport and accumulation of Ca2+ ions to the mineralization front during dentinogenesis. These cells are known to carry membrane-bound ATP-driven pumps and Na+/Ca2+ antiports for Ca2+ extrusion, but little is known about Ca2+ influx mechanisms into these cells. It has been shown that the administration of Ca2+ channel blockers in vivo strongly impairs Ca2+ uptake in the mineral phase during dentinogenesis in the rat; the present in vitro study is aimed at further elucidating odontoblast Ca2+ uptake mechanisms. Dissected rat incisor odontoblasts exhibited a pronounced fluorescence when incubated with a fluorescently-labeled (STBodipy) dihydropyridine, which is specific for voltage-gated Ca2+ channels of the L-type, and this binding was competitively abolished by nifedipine. As assayed by fluorescence spectrometry, odontoblast Ca2+ uptake was enhanced by the agonistic dihydropyridine BAYK-8644 (5 μM) as well as by plasma membrane depolarization in a high K+ (120 mM) medium. The Ca2+ uptake after depolarization was impaired by nifedipine (5 μM). When treated with the Ca2+-ATPase inhibitor cyclopiazonic acid (CPA; 10 μM), a nonvoltage-gated uptake of 45Ca2+ was identified. This uptake was not influenced by nifedipine (20 μM) but was impaired by lanthanum ions (200 μM). A nonvoltage-gated uptake of Mn2+ into CPA-treated cells could be traced using the fura-2 quenching technique. This CPA-induced Ca2+ flux was not caused by an alteration of the plasma membrane potential, as assayed with di-8-ANEPPS. The results demonstrate that Ca2+ flux into dentinogenically active odontoblasts occurs through voltage-gated Ca2+ channels of the L-type and by nonvoltage-gated, agonist-sensitive Ca2+ uptake pathways.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002239900189
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  • 4
    Electronic Resource
    Electronic Resource
    Experimental investigation of microbursts (1996)
    Springer
    Experiments in fluids 21 (1996), S. 17-25 
    Details
    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 An isolated dynamic microburst is modelled in the laboratory by releasing an elevated volume of salt water solution which is slightly heavier than ambient fresh water, allowing it to fall onto a horizontal plate and develop into a turbulent microburst vortex ring. This experimental model exhibits many of the features of naturally occurring microbursts which are known to be a hazard to aviation. Flow visualization methods are used to observe the event and a high resolution video camera is used to record it. In the current investigation hot film velocity measurements are made at a number of radial positions near the ground. Realistic estimates of the wind field in real microbursts may be obtained from these measurements by means of a previously developed scaling law. Flow visualization and velocity measurements support a description of the microburst structure in its transition from a vortex dominated flow to a radial gravity current in its late stages.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00204631
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  • 5
    Electronic Resource
    Electronic Resource
    Ca2+ Uptake Through Voltage-gated L-type Ca2+ Channels by Polarized Enterocytes from Atlantic Cod Gadus morhua (1998)
    Springer
    The journal of membrane biology 164 (1998), S. 229-237 
    Details
    ISSN: 1432-1424
    Keywords: Key words: BAY K-8644 — nifedipine — (-)-STBodipy —ω-conotoxin — intestine — teleost
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract. The presence and localization of voltage-gated Ca2+ channels of L-type were investigated in intestinal cells of the Atlantic cod. Enterocytes were loaded with the fluorescent Ca2+ probe, fure-2/AM and changes in intracellular Ca2+ concentrations ([Ca2+] i ) were measured, in cell suspensions, in the presence of high potassium levels (100 mm), BAY K-8644 (5 μm), nifedipine (5 μm) or ω-conotoxin (1 μm). L-type Ca2+ channels were visualized on intestinal sections using the fluorescent dihydropyridine (-)-STBodipy. Depolarization of the plasma membrane produced a rapid (within 5 sec) and transient (at basal levels after 21 sec) increase in [Ca2+] i . BAY K-8644 increased the [Ca2+] i by 7.2%. Cells in a Ca2+-free buffer increased [Ca2+] i after addition of 10 mm Ca2+, and this increase was abolished by nifedipine in both depolarizing and normal medium but not by ω-conotoxin. Single cell experiments using video microscopy revealed that enterocytes remained polarized several hours after preparation and that the Ca2+ entry and extrusion occurred at specific and different regions of the enterocyte outer membrane. Fluorescent staining of L-type Ca2+ channels in the intestinal mucosa showed the most intense staining at the brushborder membrane. These results demonstrate the presence of voltage gated L-type Ca2+ channels in enterocytes from the Atlantic cod. The channels are mainly located at the apical side of the cells, and there is a polarized uptake of Ca2+ into the enterocytes. This suggests that the L-type Ca2+ channels are involved in the transcellular Ca2+ entry into the enterocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002329900408
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  • 6
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    Experimental investigation of microbursts (1996)
    Springer
    Details
    Publication Date: 1996-05-01
    Print ISSN: 0723-4864
    Electronic ISSN: 1432-1114
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Published by Springer
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  • 7
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    Transition to turbulence in an elliptic vortex (1996)
    Cambridge University Press
    Details
    Publication Date: 1996-01-25
    Description: Stability and transition to turbulence are studied in a simple incompressible two-dimensional bounded swirling flow with a rectangular planform - a vortex in a box. This flow is unstable to three-dimensional disturbances. The instability takes the form of counter-rotating swirls perpendicular to the axis which bend the vortex into a periodic wave. As these swirls grow in amplitude the primary vorticity is compressed into thin vortex layers. These develop secondary instabilities which roll up into vortex tubes. In this way the flow attains a turbulent state which is populated by intense elongated vortex tubes and weaker vortex layers which spiral around them. The flow was computed at two Reynolds numbers by spectral methods with up to 2563 resolution. At the higher Reynolds number broad three-dimensional shell-averaged energy spectra are found with nearly a decade of Kolmogorov k-5/3 law and small-scale isotropy.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Cambridge University Press
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  • 8
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    Slow flow through stationary random beds and suspensions of spheres (1972)
    Cambridge University Press
    Details
    Publication Date: 1972-01-25
    Description: Stokes flow through a random, moderately dense bed of spheres is treated by a generalization of Brinkman's (1947) method, which is applicable to both stationary beds and suspensions. For stationary beds, Darcy's law with a permeability result similar to Brinkman's is derived. For suspensions an effective viscosity μ/(1–2·60ψ) is found, where ψ is the volume fraction of spheres. Also, an expression for the settling velocity is derived. © 1972, Cambridge University Press. All rights reserved.
    Print ISSN: 0022-1120
    Electronic ISSN: 1469-7645
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Published by Cambridge University Press
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