1,056 research outputs found

    Introducing sectoral models into regional management: an assessment of regulatory impacts on the economy

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    Regardless of the geography of regions, management at the regional level, both in Russia and the Baltic Sea countries, faces many challenges. Hence, it is necessary to search for new effective economic management tools, since traditional approaches and modeling practices at the regional level are not suitable for either analysing various types of impact on regional economy (production, market (product), sector, region), or assessment of their consequences and identification of the necessary measures in any given economic conditions. The authors construct sectoral models to assess regulatory impacts on regional economic performance. Assessments of regulatory impacts on product value chains, economic sectors, and regions as a whole show good repeatability, which makes it possible to provide a rationale for economic decision-making. The authors propose new sectoral models using the Kaliningrad region as an example. The models are used in a comprehensive analysis of conditions for a GRP growth resulting from an increase in sectoral contributions. To this end, the study uses the well-known approaches of simulation modelling, as well as qualitative and quantitative methods in combination with economic-mathematical optimisation models. The article presents a pilot model of regulatory impacts for selected sectors of the Kaliningrad economy. The developed and tested models suggest that a rationale for economic decision-making and consequent actions should be based on the assessment of the impact of different groups of external, internal, and independent factors on value chains, based on the criterion of optimal factor income. In conclusion, the authors offer recommendations for using the proposed models in business, public administration and regional economic modeling

    Evidence for Antiferromagnetic Order in La2x_{2-x}Cex_{x}CuO4_{4} from Angular Magnetoresistance Measurements

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    We investigated the in-plane angular magnetoresistivity (AMR) of T% T^{^{\prime}}-phase La2x_{2-x}Cex_{x}CuO4_{4} (LCCO) thin films (x=0.060.15% x=0.06-0.15) fabricated by a pulsed laser deposition technique. The in-plane AMR with Hab\mathbf{H}\parallel ab shows a twofold symmetry instead of the fourfold behavior found in other electron-doped cuprates such as Pr2x% _{2-x}Cex_{x}CuO4_{4} and Nd2x_{2-x}Cex_{x}CuO4_{4}. The twofold AMR disappears above a certain temperature, TDT_{D}. The TD(x)T_{D}(x) is well above Tc(x)T_{c}(x) for x=0.06x=0.06 (110\sim 110 K), and decreases with increasing doping, until it is no longer observed above Tc(x)T_{c}(x) at x=0.15x=0.15. This twofold AMR below TD(x)T_{D}(x) is suggested to originate from an antiferromagnetic or spin density wave order.Comment: to be published in Phys. Rev. B, Vol. 80 (2009

    Double giant resonances in deformed nuclei

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    We report on the first microscopic study of the properties of two-phonon giant resonances in deformed nuclei. The cross sections of the excitation of the giant dipole and the double giant dipole resonances in relativistic heavy ion collisions are calculated. We predict that the double giant dipole resonance has a one-bump structure with a centroid 0.8 MeV higher than twice energy for the single giant dipole resonance in the reaction under consideration. The width of the double resonance equals to 1.33 of that for the single resonance.Comment: 5 pages, 2 postscript figure

    Gamow-Teller strength distributions at finite temperatures and electron capture in stellar environments

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    We propose a new method to calculate stellar weak-interaction rates. It is based on the Thermo-Field-Dynamics formalism and allows the calculation of the weak-interaction response of nuclei at finite temperatures. The thermal evolution of the GT+_+ distributions is presented for the sample nuclei 54,56^{54, 56}Fe and ~76,78,80^{76,78,80}Ge. For Ge we also calculate the strength distribution of first-forbidden transitions. We show that thermal effects shift the GT+_+ centroid to lower excitation energies and make possible negative- and low-energy transitions. In our model we demonstrate that the unblocking effect for GT+_+ transitions in neutron-rich nuclei is sensitive to increasing temperature. The results are used to calculate electron capture rates and are compared to those obtained from the shell model.Comment: 16 pages, 9 figure

    Optical models of the molecular atmosphere

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    The use of optical and laser methods for performing atmospheric investigations has stimulated the development of the optical models of the atmosphere. The principles of constructing the optical models of molecular atmosphere for radiation with different spectral composition (wideband, narrowband, and monochromatic) are considered in the case of linear and nonlinear absorptions. The example of the development of a system which provides for the modeling of the processes of optical-wave energy transfer in the atmosphere is presented. Its physical foundations, structure, programming software, and functioning were considered

    Analysis of Terminal Deletions using a Generalized Time-Dependent Model of Radiation-Induced Formation of Chromosomal Aberrations

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    We have developed a model that can simulate different types of radiation induced chromosomal aberrations (CA's) and can provide predictions on the frequency and size of chromosomes with terminal deletions. Chromosomes with terminal deletions lack telomeres and this can elicit sister chromatid unions and the prolonged breakage/fusion/bridge (B/F/B) cycles that have been observed in mammalian tumors. The loss of a single telomere has been shown to cause extensive genomic instability through the B/F/B cycle process. Our model uses a stochastic process of DNA broken end joining, in which a realistic spectrum of CA's is created from improperly joined DNA free ends formed by DNA double strand breaks (DSBs). The distribution of the DNA free ends is given by a mechanistic model that takes into account the chromatin structure and track structure for high-LET radiation. The model allows for DSB clustering from high-LET radiation and simulates the formation of CA's in stages that correspond to the actual time after radiation exposure. The time scale for CA formation is derived from experimental data on DSB repair kinetics. At any given time a nucleus may have intact chromosomes, CA's, and/or unrepaired fragments, some of which are defined as terminal deletions, if they are capped by one telomere. The model produces a spectrum of terminal deletions with their corresponding probabilities and size distributions for different heavy ions exposures for the first division after exposure. This data provides valuable information because there is limited experimental data available in the literature on the on the actual size of terminal deletions. We compare our model output to the available experimental data and make a reasonable extrapolation on the number of chromosomes lacking telomeres in human lymphocytes exposed to heavy ions. This model generates data which may lead to predictions on the rate of genomic instability in cells after exposure to high charge and energy nuclei affecting astronauts during space missions

    The Distribution of Chromosomal Aberrations in Human Cells Predicted by a Generalized Time-Dependent Model of Radiation-Induced Formation of Aberrations

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    New experimental data show how chromosomal aberrations for low- and high-LET radiation are dependent on DSB repair deficiencies in wild-type, AT and NBS cells. We simulated the development of chromosomal aberrations in these cells lines in a stochastic track-structure-dependent model, in which different cells have different kinetics of DSB repair. We updated a previously formulated model of chromosomal aberrations, which was based on a stochastic Monte Carlo approach, to consider the time-dependence of DSB rejoining. The previous version of the model had an assumption that all DSBs would rejoin, and therefore we called it a time-independent model. The chromosomal-aberrations model takes into account the DNA and track structure for low- and high-LET radiations, and provides an explanation and prediction of the statistics of rare and more complex aberrations. We compared the program-simulated kinetics of DSB rejoining to the experimentally-derived bimodal exponential curves of the DSB kinetics. We scored the formation of translocations, dicentrics, acentric and centric rings, deletions, and inversions. The fraction of DSBs participating in aberrations was studied in relation to the rejoining time. Comparisons of simulated dose dependence for simple aberrations to the experimental dose-dependence for HF19, AT and NBS cells will be made

    The applicability of acoustic emission method to modeling the endurance of metallic construction elements

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    Acoustic emission method is the most effective nondestructive inspection technique of construction elements. This paper considers the expanded applicability of acoustic emission method to modeling the damage and the remaining operational life of building structures, including the high-ductile metals. The modeling of damage accumulation was carried out to predict endurance using acoustic emission method

    Population of isomers in decay of the giant dipole resonance

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    The value of an isomeric ratio (IR) in N=81 isotones (137^{137}Ba, 139^{139}Ce, 141^{141}Nd and 143^{143}Sm) is studied by means of the (γ,n)\gamma, n) reaction. This quantity measures a probability to populate the isomeric state in respect to the ground state population. In (γ,n)\gamma, n) reactions, the giant dipole resonance (GDR) is excited and after its decay by a neutron emission, the nucleus has an excitation energy of a few MeV. The forthcoming γ\gamma decay by direct or cascade transitions deexcites the nucleus into an isomeric or ground state. It has been observed experimentally that the IR for 137^{137}Ba and 139 ^{139}Ce equals about 0.13 while in two heavier isotones it is even less than half the size. To explain this effect, the structure of the excited states in the energy region up to 6.5 MeV has been calculated within the Quasiparticle Phonon Model. Many states are found connected to the ground and isomeric states by E1E1, E2E2 and M1M1 transitions. The single-particle component of the wave function is responsible for the large values of the transitions. The calculated value of the isomeric ratio is in very good agreement with the experimental data for all isotones. A slightly different value of maximum energy with which the nuclei rest after neutron decay of the GDR is responsible for the reported effect of the A-dependence of the IR.Comment: 16 pages, 4 Fig

    Investigation of LiFeAs by means of "Break-junction" Technique

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    In our tunneling investigation using Andreev superconductor - normal metal - superconductor contacts on LiFeAs single crystals we observed two reproducible independent subharmonic gap structures at dynamic conductance characteristics. From these results, we can derive the energy of the large superconducting gap ΔL=(2.5÷3.4)\Delta_L=(2.5 \div 3.4) meV and the small gap ΔL=(0.9÷1)\Delta_L=(0.9 \div 1) meV at T=4.2T = 4.2 K for the TClocal(10.5÷14)T_C^{local} \approx (10.5 \div 14) K (the contact area critical temperature which deviation causes the variation of ΔL\Delta_L). The BCS-ratio is found to be 2ΔL/kBTC=(4.6÷5.6)2\Delta_L/k_BT_C = (4.6 \div 5.6), whereas 2ΔS/kBTC3.522\Delta_S/k_BT_C \ll 3.52 results from induced superconductivity in the bands with the small gap.Comment: 7 pages, 5 figures. Published in Pis'ma v ZhETF 95, 604-610 (2012
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