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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical physics, analysis and geometry 1 (1998), S. 193-221 
    ISSN: 1572-9656
    Keywords: m-function ; Schrödinger operator ; spectrum
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract This paper presents a new approach to spectral theory for theSchrödinger Operator on the half-line. Solutions of nonlinearRiccati-type equations related to the Schrödinger equation at realspectral parameter λ are characterised by means of their clusteringproperties as λ is varied. A family of solutions exhibiting aso-called δ-clustering property is shown to imply precise estimatesfor the complex boundary value of the Weyl m-function and thespectral measure, and leads to an analysis of the absolutely continuouscomponent of the spectral measure in terms of stability criteria for thecorresponding Riccati equations.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Mathematical physics, analysis and geometry 3 (2000), S. 385-403 
    ISSN: 1572-9656
    Keywords: Herglotz functions ; hyperbolic geometry ; m-function ; Schrödinger operator ; spectral theory ; value distribution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mathematics , Physics
    Notes: Abstract We consider the Dirichlet Schrödinger operator T=−(d2/d x 2)+V, acting in L 2(0,∞), where Vis an arbitrary locally integrable potential which gives rise to absolutely continuous spectrum. Without any other restrictive assumptions on the potential V, the description of asymptotics for solutions of the Schrödinger equation is carried out within the context of the theory of value distribution for boundary values of analytic functions. The large xasymptotic behaviour of the solution v(x,λ) of the equation T f(x,λ)=λf(x,λ), for λ in the support of the absolutely continuous part μa.c. of the spectral measure μ, is linked to the spectral properties of this measure which are determined by the boundary value of the Weyl–Titchmarsh m-function. Our main result (Theorem 1) shows that the value distribution for v′(N,λ)/v(N,λ) approaches the associated value distribution of the Herglotz function m N (z) in the limit N→∞, where m N (z) is the Weyl–Titchmarsh m-function for the Schrödinger operator −(d2/d x 2)+Vacting in L 2(N,∞), with Dirichlet boundary condition at x=N. We will relate the analysis of spectral asymptotics for the absolutely continuous component of Schrödinger operators to geometrical properties of the upper half-plane, viewed as a hyperbolic space.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 1589-1597 
    ISSN: 0887-6266
    Keywords: rheology of entangled polymers at high shear rates ; relaxation of entangled polymers under high shear ; nonlinear transient flow behavior of entangled polymers ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A new model is presented for describing the time-dependent flow of entangled polymer liquids at high shear rates. The results were obtained by extending the Doi and Edwards theory to include the effect of chain stretching. This nonlinear phenomenon is predicted to occur when the product of the shear rate and longitudinal relaxation time of the polymer exceeds one. If a constant-shear-rate flow is started under these conditions, it is shown that the shear stress and the normal stress are considerably larger than that predicted by the original reptation model. We also find that both of these stresses can pass through maxima before reaching a steady state and that the times required to reach these maxima are constants independent of the shear rate. In general the new model requires the numerical solution of coupled partial differential equations. However, at the highest shear rates where reptative relaxation is no longer important, an analytical solution for the stresses is found. The results obtained here are shown to agree well with experimental data and to be an improvement over a simpler model recently proposed.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 21 (1977), S. 3193-3209 
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The physical properties of radiation- and sulfur-cured poly(butadiene-co-styrene)-based stocks were compared. It was found that the measured lower ultimate strength of radiation-cured stocks is in part attributable to the difference in the glass transition temperatures of the stocks cured by the two methods (an increase in Tg is caused by sulfur curing). Another factor contributing to the difference in performance is the apparent nonuniform crosslink density distribution in radiationcured stocks containing carbon black filler. A higher crosslink density in the immediate vicinity of carbon black particles was postulated based on a to-be-expected distribution of secondary electron energy at interfaces with an appreciable change in density between neighboring phases. The invoked difference in network topology, supported by solvent swelling measurements on sulfur- and radiation-crosslinked vulcanizates can explain not only the slightly lower ultimate strength of radiation-cured stocks but also the superior fatigue and crack propagation performance measured for these culcanizates. Finally, theoretical arguments were presented to explain the inferred large strength deficiency of radiation-cured rubbers reported by other investigators on the basis of chain scissions encountered during radiation crosslinking.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science Part A-1: Polymer Chemistry 8 (1970), S. 2103-2108 
    ISSN: 0449-296X
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Irradiation of terephthalophenone in isopropyl alcohol gave a bright yellow-colored intermediate which decayed rather rapidly. The products were complex and depended upon the mode of irradiation. They ranged from a mixed polymer I to a dimer II. I consisted of about 5 terephthalophenone units capped with hydrogen or isopropyl alcohol radicals or terminated by cyclization. II, the dimer, was capped by hydrogen atoms.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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