1,715 research outputs found

    Quantum geometrodynamics of the Bianchi IX model in extended phase space

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    A way of constructing mathematically correct quantum geometrodynamics of a closed universe is presented. The resulting theory appears to be gauge-noninvariant and thus consistent with the observation conditions of a closed universe, by that being considerably distinguished from the conventional Wheeler - DeWitt one. For the Bianchi-IX cosmological model it is shown that a normalizable wave function of the Universe depends on time, allows the standard probability interpretation and satisfies a gauge-noninvariant dynamical Schrodinger equation. The Wheeler - DeWitt quantum geometrodynamics is represented by a singular, BRST-invariant solution to the Schrodinger equation having no property of normalizability.Comment: LaTeX, 18 pages, to be published in Int. J. Mod. Phys.

    Re-entrant resonant tunneling

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    We study the effect of electron-electron interactions on the resonant-tunneling spectroscopy of the localized states in a barrier. Using a simple model of three localized states, we show that, due to the Coulomb interactions, a single state can give rise to two resonant peaks in the conductance as a function of gate voltage, G(Vg). We also demonstrate that an additional higher-order resonance with Vg-position in between these two peaks becomes possibile when interactions are taken into account. The corresponding resonant-tunneling process involves two-electron transitions. We have observed both these effects in GaAs transistor microstructures by studying the time evolution of three adjacent G(Vg) peaks caused by fluctuating occupation of an isolated impurity (modulator). The heights of the two stronger peaks exibit in-phase fluctuations. The phase of fluctuations of the smaller middle peak is opposite. The two stronger peaks have their origin in the same localized state, and the third one corresponds to a co-tunneling process.Comment: 9 pages, REVTeX, 4 figure

    Timing properties of gamma-ray bursts detected by SPI-ACS detector on board of INTEGRAL

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    We study timing properties of a large sample of gamma-ray bursts (GRB) detected by the Anti-Coincidence Shield (ACS) of the SPI spectrometer of INTEGRAL telescope. We identify GRB-like events in the SPI-ACS data. The data set under investigation is the history of count rate of the SPI-ACS detector recorded with a binning of 50 ms over the time span of ~10 yr. In spite of the fact that SPI-ACS does not have imaging capability, it provides high statistics signal for each GRB event, because of its large effective area. We classify all isolated excesses in the SPI-ACS count rate into three types: short spikes produced by cosmic rays, GRBs and Solar flare induced events. We find some ~1500 GRB-like events in the 10 yr exposure. A significant fraction of the GRB-like events identified in SPI-ACS occur in coincidence with triggers of other gamma-ray telescopes and could be considered as confirmed GRBs. We study the distribution of durations of the GRBs detected by SPI-ACS and find that the peak of the distribution of long GRBs is at ~ 20, i.e. somewhat shorter than for the long GRBs detected by BATSE. Contrary to the BATSE observation, the population of short GRBs does not have any characteristic time scale. Instead, the distribution of durations extends as a powerlaw to the shortest time scale accessible for SPI-ACS, < 50 ms. We also find that a large fraction of long GRBs has a characteristic variability time scale of the order of 1 s. We discuss the possible origin of this time scale.Comment: Accepted for publication in A&

    The generality of inflation in some closed FRW models with a scalar field

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    The generality of inflation in closed FRW Universe is studied for the models with a scalar field on a brane and with a complex scalar field. The results obtained are compared with the previously known results for the model with a scalar field and a perfect fluid. The influence of the measure chosen in the initial condition space on the ratio of inflationary solution is described.Comment: 15 pages with 5 eps figures; small corrections in text; final version to appear in Int. J. Mod. Phys.

    Науково-методичні підходи до оцінки кадрового потенціалу медичного закладу (Scientific and methodical approaches to personnel potential estimation at the medical institution)

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    У статті розглянуто наукові підходи до оцінки кадрового потенціалу медичного закладу, до оцінювання якості робочої сили та критерії оцінки якості кадрового потенціалу підприємства. Проведено аналіз наявних методик оцінки кадрового потенціалу. Систематизовано методи оцінки кадрового потенціалу та виявлено вимоги до складання дієвих методик оцінки кадрового потенціалу. Запропоновано модель оцінки кадрового потенціалу медичного закладу. Надано пропозиції щодо створення єдиної системи оцінки персоналу та розглянуто моделі оцінювання кадрового потенціалу медичного закладу. (The article utilizes scientific approaches to assessing the human resources capacity of a medical institution. The approaches to the quality assessment of the workforce are defined, the criteria for assessing the quality of the enterprise personnel potential are specified. The existing methods of the staff potential assessing are analyzed. The methods for assessing human resources are systematized and the requirements for the formulation of effective human resources assessing techniques are identified. A model for assessing the human resources capacity of a medical institution was proposed. Proposals for the creation of a unified system for personnel assessment are presented and models for assessing the human resources capacity of the medical institution are considered.

    The exact cosmological solution to the dynamical equations for the Bianchi IX model

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    Quantum geometrodynamics in extended phase space describes phenomenologically the integrated system ``a physical object + observation means (a gravitational vacuum condensate)''. The central place in this version of QGD belongs to the Schrodinger equation for a wave function of the Universe. An exact solution to the ``conditionally-classical'' set of equations in extended phase space for the Bianchi-IX model and the appropriate solution to the Schrodinger equation are considered. The physical adequacy of the obtained solutions to existing concepts about possible cosmological scenarios is demonstrated. The gravitational vacuum condensate is shown to be a cosmological evolution factor.Comment: LaTeX, 14 pages, to be published in Int. J. Mod. Phys.

    Enhanced fluctuations of the tunneling density of states near bottoms of Landau bands measured by a local spectrometer

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    We have found that the local density of states fluctuations (LDOSF) in a disordered metal, detected using an impurity in the barrier as a spectrometer, undergo enhanced (with respect to SdH and dHvA effects) oscillations in strong magnetic fields, omega _c\tau > 1. We attribute this to the dominant role of the states near bottoms of Landau bands which give the major contribution to the LDOSF and are most strongly affected by disorder. We also demonstrate that in intermediate fields the LDOSF increase with B in accordance with the results obtained in the diffusion approximation.Comment: 4 pages, 4 figure
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