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    Non-trivial stably free modules over crossed products

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    We consider the class of crossed products of noetherian domains with universal enveloping algebras of Lie algebras. For algebras from this class we give a sufficient condition for the existence of projective non-free modules. This class includes Weyl algebras and universal envelopings of Lie algebras, for which this question, known as noncommutative Serre's problem, was extensively studied before. It turns out that the method of lifting of non-trivial stably free modules from simple Ore extensions can be applied to crossed products after an appropriate choice of filtration. The motivating examples of crossed products are provided by the class of RIT algebras, originating in non-equilibrium physics.Comment: 13 page

    Complex Susceptibility of Liquid Water as a Two-Potential System of Reorienting Polar Molecules

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    The theory elaborated in ref. 1 and 2 is applied to the calculation of the liquid water wide-band (0 < ν/cm^(-1) < 1000) dielectric spectra. These comprise the Debye relaxation region at the centimetre/millimetre wavelengths and the two-humped absorption coefficient frequency dependence in the far infrared (FIR) region. It is supposed that a major part of H2O molecules, called [L]-particles or [L]-molecules, are bonded by relatively strong H-bonds; [L]-molecules perform librations of relatively small amplitude β (β is about 20°). The remaining molecules called R-molecules have more rotational / translational mobility. A new microscopic molecular confined rotator / doble well potential (CR DWP) model of liquid water is developed. The contributions of [L]-and [R]-molecules to the complex permittivity ε are found on the basis of the confined rotator (CR) and the double well potential (DWP) models, with rectangular and cos^2(θ) intermolecular potential profiles, respectively. It is shown that the CR/DWP model gives a good description of the Debye relaxation and a qualitative description of FIR the dielectric spectra of water
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