1,746 research outputs found

    The Fedosov manifolds and magnetic monopole

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    A non-symplectic generalization of Hamiltonian mechanics is considered. It allows include into consideration "non-Lagrange" systems, such as theory of charged particle in the field of magnetic monopole. The corresponding generalization for the Fedosov manifolds is given. The structure of phase space of "charged particle in the field of magnetic monopole" is studied.Comment: 14 page

    Nutrition During Long Flight

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    The nutrition of astronautics during long flights is discussed, especially with respect to the changes brought about in the body by the condition of weightlessness

    Photon collimator system for the ILC Positron Source

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    High energy e+e- linear colliders are the next large scale project in particle physics. They need intense sources to achieve the required luminosity. In particular, the positron source must provide about 10E+14 positrons per second. The positron source for the International Linear Collider (ILC) is based on a helical undulator passed by the electron beam to create an intense circularly polarized photon beam. With these photons a longitudinally polarized positron beam is generated; the degree of polarization can be enhanced by collimating the photon beam. However, the high photon beam intensity causes huge thermal load in the collimator material. In this paper the thermal load in the photon collimator is discussed and a flexible design solution is presented.Comment: 22 pages, 19 figures, 8 tables, cross-reference to table 4 fixe

    Electronic structure of V4_4O7_7: charge ordering, metal-insulator transition and magnetism

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    The low and high-temperature phases of V4_4O7_7 have been studied by \textit{ab initio} calculations. At high temperature, all V atoms are electronically equivalent and the material is metallic. Charge and orbital ordering, associated with the distortions in the V pseudo-rutile chains, occur below the metal-insulator transition. Orbital ordering in the low-temperature phase, different in V3+^{3+} and V4+^{4+} chains, allows to explain the distortion pattern in the insulating phase of V4_4O7_7. The in-chain magnetic couplings in the low-temperature phase turn out to be antiferromagnetic, but very different in the various V4+^{4+} and V3+^{3+} bonds. The V4+^{4+} dimers formed below the transition temperature form spin singlets, but V3+^{3+} ions, despite dimerization, apparently participate in magnetic ordering.Comment: 10 pages, 6 figures, 2 table

    Orbital structure and magnetic ordering in stoichiometric and doped crednerite CuMnO2

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    The exchange interactions and magnetic structure in layered system CuMnO2 (mineral crednerite) and in nonstoichiometric system Cu1.04Mn0.96O2, with triangular layers distorted due to orbital ordering of the Mn3+ ions, are studied by ab-initio band-structure calculations, which were performed within the GGA+U approximation. The exchange interaction parameters for the Heisenberg model within the Mn-planes and between the Mn-planes were estimated. We explain the observed in-plane magnetic structure by the dominant mechanism of the direct d-d exchange between neighboring Mn ions. The superexchange via O ions, with 90 degree Mn-O-Mn bonds, plays less important role for the in-plane exchange. The interlayer coupling is largely dominated by one exchange path between the half-filled 3z^2-r^2 orbitals of Mn3+. The change of interlayer coupling from antiferromagnetic in pure CuMnO2 to ferromagnetic in doped material is also explained by our calculations

    Design of Pre-Dumping Ring Spin Rotator with a Possibility of Helicity Switching for Polarized Positrons at the ILC

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    The use of polarized beams enhance the possibility of the precision measurements at the International Linear Collider (ILC). In order to preserve the degree of polarization during beam transport spin rotators are included in the current TDR ILC Lattice. In this report some advantages of using a combined spin rotator/spin flipper are discussed. A few possible lattice designs of spin flipper developed at DESY in 2012 are presented.Comment: Talk presented at the International Workshop on Future Linear Colliders (LCWS15), Whistler, Canada, 2-6 November 201

    Transformation of approaches to determine influence factors in the economic development models

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    Purpose: The research paper deals with the development of new scientific solutions regarding the identification of influence factors in the economic development models for developed and developing countries. The paper emphasizes the key significance of modelling within the framework of the study of economic growth at the level of world, national and regional economies (macro- and mesolevel). Design/methodology/approach: To achieve the objectives of this study the main components of economic development models were discussed. Findings: The transformation of the approaches of scholars to identify the influence factors within the historical change of the economic development models is noted. It was emphasized that the overwhelming majority of scholars use three factors of influence (land, labour, capital) and their derivatives in the “old”, “new” and regional economic development models, which is insufficient in the current conditions of economic systems at the macro- and mesolevel. Practical implications: Two related economic development models for developed countries and developing countries are proposed for use; key influence factors within these models are identified. Originality/value: It is emphasized that capital, human resources, level of innovations and competitive advantages are important for ensuring the economic development of developed countries, and the level of corruption and the level of the shadow economy are added to the above-mentioned components for developing countries.peer-reviewe

    Внешняя среда как фактор выбора места проживания

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    Many people have certain problems with the choice of the place of living. The main idea of this article is to study the aspects of urban area environment which effect on this decision. The influence of these factors is analyzed on example of two cities: the big one and the small one.Многие люди имеют определенные проблемы при выборе места жительства. Основной идеей данной статьи является изучение аспектов городской окружающей среды, которые влияют на выбор места проживания людей. Влияние этих факторов анализируется на примере двух городов: один большой и один маленький по градостроительной классификации

    Body composition data from the rat subjects of Cosmos 1129 experiment K-316

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    The effects of 18.5 days of weightlessness on the body composition of young, growing, male laboratory rats were examined. Three groups of 5 rats each were examined. It is indicated that exposure of young, growing, male rats to 18.5 days of weightlessness produces: (1) no effect on the quantity of fat stored by the body; (2) a slight reduction in the quantity of fat free tissue laid down by the body; (3) a small reduction in the fraction of water contained by the fat free body mass; (4) a similar reduction in the fraction of water contained by the fat free skin and fat free carcass; (5) a shift in relative distribution of the total body water from skin to viscera; (6) a diminution in the fraction of extracellular water contained by the fat free body; (7) no effect on the fraction of total skeletal musculature contained by the fat free body, as indicated by body creatine content; (8) a sizeable reduction in the fraction of bone mineral contained by the fat free body, as calculated from body calcium content. The nature of the physiological changes induced by unloading from Earth gravity in the mammalian organism are illustrated
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