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  • Articles: DFG German National Licenses  (2)
  • 45P05  (1)
  • DBA/2 mice  (1)
  • 1
    Electronic Resource
    Electronic Resource
    On numerical cubatures of singular surface integrals in boundary element methods (1992)
    Springer
    Numerische Mathematik 62 (1992), S. 343-369 
    Details
    ISSN: 0945-3245
    Keywords: 65D30 ; 47G30 ; 45P05 ; 58G15
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics
    Notes: Summary We present and analyze methods for the accurate and efficient evaluation of weakly, Cauchy and hypersingular integrals over piecewise analytic curved surfaces in ℝ3. The class of admissible integrands includes all kernels arising in the numerical solution of elliptic boundary value problems in three-dimensional domains by the boundary integral equation method. The possibly not absolutely integrable kernels of boundary integral operators in local coordinates are pseudohomogeneous with analytic characteristics depending on the local geometry of the surface at the source point. This rules out weighted quadrature approaches with a fixed singular weight. For weakly singular integrals it is shown that Duffy's triangular coordinates leadalways to a removal of the kernel singularity. Also asymptotic estimates of the integration error are provided as the size of the boundary element patch tends to zero. These are based on the Rabinowitz-Richter estimates in connection with an asymptotic estimate of domains of analyticity in ℂ2. It is further shown that the modified extrapolation approach due to Lyness is in the weakly singular case always applicable. Corresponding error and asymptotic work estimates are presented. For the weakly singular as well as for Cauchy and hypersingular integrals which e.g. arise in the study of crack problems we analyze a family of product integration rules in local polar coordinates. These rules are hierarchically constructed from “finite part” integration formulas in radial and Gaussian formulas in angular direction. Again, we show how the Rabinowitz-Richter estimates can be applied providing asymptotic error estimates in terms of orders of the boundary element size.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01396234
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Autoradiography of muscarinic cholinergic receptors in cortical and subcortical brain regions of C57BL/6 and DBA/2 mice (1992)
    Springer
    Neurochemical research 17 (1992), S. 1057-1062 
    Details
    ISSN: 1573-6903
    Keywords: [3H]QNB ; [3H]pirenzepine ; autoradiography ; C57BL/6 mice ; DBA/2 mice
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Mice of the inbred strains C57BL/6 and DBA/2 show strain-dependent behavioural differences which have been correlated with variations in brain cholinergic systems. In the present study, the density of muscarinic cholinergic receptors in both strains of mice was determined by autoradiographic methods using [3H]quinuclidinyl benzilate (QNB) and [3H]pirenzepine as ligands. C57BL/6 mice showed a significantly lower [3H]QNB binding level in the frontal cortex by one third as compared to DBA/2 mice. In the striatum and the cholinergic pontomesencephalic nucleus laterodorsalis tegmenti the [3H]QNB binding was lower in C57BL/6 by 28% and 31%, respectively. The [3H]pirenzepine binding level was found to be significantly higher in C57BL/6 temporal cortex (by 22%). These results are discussed in relation to interstrain differences in cholinergic cell density and in the activity of cholinergic enzymes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00967281
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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