1,560 research outputs found

    Dieudonn\'e modules and pp-divisible groups associated with Morava KK-theory of Eilenberg-Mac Lane spaces

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    We study the structure of the formal groups associated to the Morava KK-theories of integral Eilenberg-Mac Lane spaces. The main result is that every formal group in the collection {K(n)K(Z,q),q=2,3,...}\{K(n)^*K({\mathbb Z}, q), q=2,3,...\} for a fixed nn enters in it together with its Serre dual, an analogue of a principal polarization on an abelian variety. We also identify the isogeny class of each of these formal groups over an algebraically closed field. These results are obtained with the help of the Dieudonn\'e correspondence between bicommutative Hopf algebras and Dieudonn\'e modules. We extend P. Goerss's results on the bilinear products of such Hopf algebras and corresponding Dieudonn\'e modules.Comment: 23 page

    Quantum Oscillations of Elastic Moduli and Softening of Phonon Modes in Metals

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    In this paper we present a theoretical analysis of the effect of magnetostriction on quantum oscillations of elastic constants in metals under strong magnetic fields. It is shown that at low temperatures a significant softening of some acoustic modes could occur near peaks of quantum oscillations of the electron density of states (DOS) at the Fermi surface (FS). This effect is caused by a magnetic instability of a special kind, and it can give rise to a lattice instability. We also show that the most favorable conditions for this instability to be revealed occur in metals whose Fermi surfaces include nearly cylindrical segments.Comment: 5 pages, 1 figur

    Insertional Achilles tendinopathy in patients with Haglund's syndrome: results of computer modeling and biomechanical research

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    In this study, a biomechanical relationship was found between the pathological process in Haglund syndrome and secondary tendinopathy of the Achilles tendon. We have developed the calculation diagram, created computer models and determined the values of the stress-strain state of the rear foot structures in the normal and with Haglund syndrome. It was found that the maximum stress values are concentrated on the Achilles tendon, but in pathological model the stress values were significantly higher than normal in the whole range of motion of the foot. Normally, maximal stress on the calcaneus is localized on its posterior surface - on the anterior surface of the retrocalcaneal recess. In Haglund syndrome, maximum stress was recorded on the upper surface of the posterior sections of the calcaneus. Haglund syndrome is marked by overloading of the calf muscle. The results of this study explain the development of degenerative changes in the AT in patients with Haglund syndrome. It was also found that the enlarged posterior-upper part of the calcaneus is a factor in the development of insertional Achilles tendinopathy, which should also be considered when choosing further treatment

    Formation of non-state pension system in the Russian Federation on an example of the activities of non-state pension fund "Sberbank"

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    The article is devoted to a problem, which is important relevant for the Russian Federation.it is studying the factors of formation of non-state system in provision of pensions. In this article, the authors have described the russian specifics of formation in the system of non-state pension provision in the Russian Federation. As the main methods, the system and structural and analytical analysis are chosen. Data and materials of the non-state pension fund of Sberbank became material of a research. The main documents regulating formations and functioning of the non-state pension funds are submitted. It is shown that one of the most perspective is activity of the non-state pension fund of Sberbank. The sources of formation of revenues of the non-state pension fund of Sberbank are described. Both individual and corporate programs of the non-state pension fund of Sberbank are submitted. The conducted research allows making conclusions that despite the undertaken reforms of provision of pensions by the citizens.peer-reviewe

    Electrical control of optical orientation of neutral and negatively charged excitons in n-type semiconductor quantum well

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    We report a giant electric field induced increase of spin orientation of excitons in n-type GaAs/AlGaAs quantum well. It correlates strongly with the formation of negatively charged excitons (trions) in the photoluminescence spectra. Under resonant excitation of neutral heavy-hole excitons, the polarization of excitons and trions increases dramatically with electrical injection of electrons within the narrow exciton-trion bias transition in the PL spectra, implying a polarization sensitivity of 200 % per Volt. This effect results from a very efficient trapping of neutral excitons by the quantum well interfacial fluctuations (so-called "natural" quantum dots) containing resident electrons.Comment: 18 pages, 4 figure

    Non-Markovian large amplitude motion and nuclear fission

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    The general problem of dissipation in macroscopic large-amplitude collective motion and its relation to energy diffusion of intrinsic degrees of freedom of a nucleus is studied. By applying the cranking approach to the nuclear many body system, a set of coupled dynamical equations for the collective classical variables and the quantum mechanical occupancies of the intrinsic nuclear states is derived. Different dynamical regimes of the intrinsic nuclear motion and its consequences on time properties of collective dissipation are discussed. The approach is applied to the descant of the nucleus from the fission barrier.Comment: 9 pages and 3 figure

    Practical experience of using ultrasound flowmeters at the measurement associated petroleum gas

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    © Published under licence by IOP Publishing Ltd. The results of field tests of several ultrasound flowmeters at existing oil and gas extraction objects are given in the paper. Measured medium - associated petroleum gas. This work aims to create a unified system for measuring the amount and parameters of APG in order to reduce operating costs
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