Given an iterated skew polynomial ring C[y1; τ1, δ1] . . . [yn; τn, δn] over a complete local ring C with maximal ideal m, we prove, under suitable assumptions, that the completion at the ideal m+ 〈y1, y2, . . . , yn〉 is an iterated skew power series ring. When C is a field, this completion is a local, noetherian, Auslander regular domain with Krull, classical Krull and global dimension all equ...

Physical understanding of the electronic properties of nanostructures allows us to fabricate the electronic elements which are widely applied as components of the new generation of electronic and photonic devices. The potential application of such elements in industry stimulates rapid development in nanotechnology and gives us motivation for preparing and studying a new class of confined struct...

We study the effect of tunneling on the electronic structure of two vertically coupled quantum rings within the spin density functional theory. The ground state configurations of the coupled rings are obtained for a system with 10 electrons as a function of the ring radius and the inter-ring distance. For small ring radius, our results recover those of coupled quantum dots. For large ring radiu...

an r-module m is called epi-retractable if every submodule of mr is a homomorphic image of m. it is shown that if r is a right perfect ring, then every projective slightly compressible module mr is epi-retractable. if r is a noetherian ring, then every epi-retractable right r-module has direct sum of uniform submodules. if endomorphism ring of a module mr is von-neumann regular, then m is semi-...

We study spin-dependent magnetoconductance in mesoscopic rings subject to an inhomogeneous in-plane magnetic field. We show that the polarization direction of transmitted spin-polarized electrons can be controlled via an additional magnetic flux such that spin flips are induced at half a flux quantum. This quantum interference effect is independent of the strength of the nonuniform field applie...

Photoluminescence and excitation of the photoluminescence spectroscopy has been performed in single InGaAs self-assembled quantum rings embedded in a field effect structure device. To determine their electronic structure, bias-dependent optical transitions have been analyzed both, for individual quantum rings, and for the averaged ensemble. Our results are compared with a theoretical model, and...

We study the complexity of some computational problems on finite black-box rings whose elements are encoded as strings of a given length and the ring operations are performed by a black-box oracle. We give a polynomial-time quantum algorithm to compute a basis representation for a given black-box ring. Using this result we obtain polynomial-time quantum algorithms for several natural computatio...