642 research outputs found

    Magnetic Properties of the low dimensional spin system (VO)2_2P2_2O7_{7}: ESR and susceptibility

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    Experimental results on magnetic resonance (ESR) and magnetic susceptibility are given for single crystalline (VO)2_2P2_2O7_{7}. The crystal growth procedure is briefly discussed. The susceptibility is interpreted numerically using a model with alternating spin chains. We determine JJ=51 K and δ\delta=0.2. Furthermore we find a spin gap of 6\approx 6meV from our ESR measurements. Using elastic constants no indication of a phase transition forcing the dimerization is seen below 300 K.Comment: 7 pages, REVTEX, 7 figure

    Effects of Two Energy Scales in Weakly Dimerized Antiferromagnetic Quantum Spin Chains

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    By means of thermal expansion and specific heat measurements on the high-pressure phase of (VO)2_2P2_2O7_7, the effects of two energy scales of the weakly dimerized antiferromagnetic SS = 1/2 Heisenberg chain are explored. The low energy scale, given by the spin gap Δ\Delta, is found to manifest itself in a pronounced thermal expansion anomaly. A quantitative analysis, employing T-DMRG calculations, shows that this feature originates from changes in the magnetic entropy with respect to Δ\Delta, Sm/Δ\partial S^{m}/ \partial \Delta. This term, inaccessible by specific heat, is visible only in the weak-dimerization limit where it reflects peculiarities of the excitation spectrum and its sensitivity to variations in Δ\Delta.Comment: 4 pages, 4 figures now identical with finally published versio

    Modern technologies of adaptation young specialists in the organization

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    In this article the main directions and technologies of adaptation of young specialists are considered. The author has revealed new technology of adaptation of young specialists which will allow new employees to feel more comfortably on a new workplace, to join collective, and also will lead to reduction of a dissatisfaction and turnover of staff at an initial stage of adaptation

    Molecular Level in Silico Studies for Oncology. Direct Models Review

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    The combination of therapy and diagnostics in one process "theranostics" is a trend in a modern medicine, especially in oncology. Such an approach requires development and usage of multifunctional hybrid nanoparticles with a hierarchical structure. Numerical methods and mathematical models play a significant role in the design of the hierarchical nanoparticles and allow looking inside the nanoscale mechanisms of agent-cell interactions. The current position of in silico approach in biomedicine and oncology is discussed. The review of the molecular level in silico studies in oncology, which are using the direct models, is presented

    Sampling Plans for Control-Inspection Schemes Under Independent and Dependent Sampling Designs With Applications to Photovoltaics

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    The evaluation of produced items at the time of delivery is, in practice, usually amended by at least one inspection at later time points. We extend the methodology of acceptance sampling for variables for arbitrary unknown distributions when additional sampling infor- mation is available to such settings. Based on appropriate approximations of the operating characteristic, we derive new acceptance sampling plans that control the overall operating characteristic. The results cover the case of independent sampling as well as the case of dependent sampling. In particular, we study a modified panel sampling design and the case of spatial batch sampling. The latter is advisable in photovoltaic field monitoring studies, since it allows to detect and analyze local clusters of degraded or damaged modules. Some finite sample properties are examined by a simulation study, focusing on the accuracy of estimation
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