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  • 1985-1989  (3)
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Material
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Year
  • 1
    Electronic Resource
    Electronic Resource
    Numerical simulation of mass injection for the formation of prominence magnetic field configurations (1988)
    Springer
    Solar physics 115 (1988), S. 81-92 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied chromospheric mass injection into an overlying coronal dipole magnetic field using a 2-D ideal magnetohydrodynamic (MHD) numerical model. The results indicate that such injection can produce magnetic field deformation conducive to active region prominences - namely, Kippenhahn-Schlüter (K-S) type configurations for stable support of injected plasma. We show the optimum conditions for such dynamical formation of K-S-type field configurations. Observations show that an active region prominence formation is preceded by the accumulation of absorptive strands above a neutral line. We hypothesize that an absorptive strand is formed by a chromospheric asymmetric mass injection into the overlying coronal magnetic field and that a necessary condition for the accumulation of the strands is that the mass injection forms a K-S-type field configuration. The results of our numerical simulation of the injection dynamics support our hypothesis. To form a K-S-type magnetic field configuration, we find that a narrow range of injection density, velocity, and magnetic field strength must be used; spicule-like, asymmetric mass injection seems favorable. The limited parameter range that exists for the formation of K-S-type magnetic field configurations in asymmetric injections may explain why active region prominences do not form everywhere on every neutral line.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146231
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Numerical simulation of mass injection for the formation of prominence magnetic field configurations (1988)
    Springer
    Solar physics 115 (1988), S. 93-106 
    Details
    ISSN: 1573-093X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We have studied symmetric mass injection into a dipole magnetic field using a 2-D ideal magnetohydrodynamic (MHD) numerical model as a simulation of the formation of Kippenhahn-Schlüter (K-S)-type quiescent prominence (QP) magnetic field configurations. The result shows that there is an optimum magnetic field strength for QP formation, suggesting why prominences do not form above every neutral line. In the model, we varied the injection velocity, density, and magnetic field strength to find the optimum conditions for the formation of a K-S-type field configuration. Such a configuration is assumed to be necessary for QP formation in which injected plasma accumulates and subsequently condenses on magnetic field lines. The condensed plasma would, then, be supported by magnetic field against gravity. We find that a weaker magnetic field strength is more favorable for the condensation but that a stronger field is more favorable for the support against gravity. These two conflicting conditions lead to an optimum field strength for a QP formation by mass injection.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00146232
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    Paper (German National Licenses)
    Fulltext
  • 3
    Electronic Resource
    Electronic Resource
    Electric field mediated stable transformation of carrot protoplasts with naked DNA (1985)
    Springer
    Plant cell reports 4 (1985), S. 355-359 
    Details
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract We have developed an electroporation procedure for the transformation of carrot protoplasts with Ti-plasmid DNA from Agrobacterium tumefaciens. The uptake of pTiC58 into carrot protoplasts was mediated by high voltage electrical pulses at field strengths from 0.5 to 3.8 kV/cm. Protoplast regeneration, somatic embryogenesis and plantlet regeneration were unaffected by the electroporation conditions selected for DNA uptake. Uptake of plasmid pTiC58 resulted in hormone independent regeneration of carrot protoplasts. Transformed somatic embryos were detected in carrot cultures 45 days after electroporation. The transformed somatic embryos developed into teratomas which synthesized nopaline. Hybridization was obtained between a labeled T-DNA fragment from pTiC58 and DNA fragments from 4 month old teratomas regenerated from electro-transformed protoplasts. Based on the number of somatic embryos regenerated after electro-transformation, a frequency of 1.6×102 transformants/104 somatic embryos/μg pTiC58 DNA was obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00269898
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    Paper (German National Licenses)
    Fulltext
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