180 research outputs found

    Mineral-petrochemical wallrock alteration of rocks in Bericul gold-ore deposit (Kuznetsk Alatau)

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    The distribution of mineral associations in near-veined zonal propylite-beresite metasomatic columns of mesothermal Bericul gold-ore deposit was analyzed. However, the polymineral composition in the inner (axial and adjacent with it rear) zones is inconsistent to the existing metasomatic column theoretical model. According to Korzhinskii metasomatic zoning theory, implied monomineral (quartz) and binary-mineral (quartz, sericite) compositions are characteristic of axial and rear zones, respectively. In common with above-mentioned facts, the zoning formation of differential component mobility is influenced by two additional factors: counter diffusion of components from fractured fluids into pores and diffusion mechanism of mass transfer it's from pores fluids into fractured of rock-fluid systems

    CeFePO: f-d hybridization and quenching of superconductivity

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    Being homologue to the new, Fe-based type of high-temperature superconductors, CeFePO exhibits magnetism, Kondo and heavy-fermion phenomena. We experimentally studied the electronic structure of CeFePO by means of angle-resolved photoemission spectroscopy. In particular, contributions of the Ce 4f-derived states and their hybridization to the Fe 3d bands were explored using both symmetry selection rules for excitation and their photoionization cross-section variations as a function of photon energy. It was experimentally found - and later on confirmed by LDA as well as DMFT calculations - that the Ce 4f states hybridize to the Fe 3d states of d_{3z^2-r^2} symmetry near the Fermi level that discloses their participation in the occurring electron-correlation phenomena and provides insight into mechanism of superconductivity in oxopnictides.Comment: 5 pages, 3 figure

    Derivative based global sensitivity measures

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    The method of derivative based global sensitivity measures (DGSM) has recently become popular among practitioners. It has a strong link with the Morris screening method and Sobol' sensitivity indices and has several advantages over them. DGSM are very easy to implement and evaluate numerically. The computational time required for numerical evaluation of DGSM is generally much lower than that for estimation of Sobol' sensitivity indices. This paper presents a survey of recent advances in DGSM concerning lower and upper bounds on the values of Sobol' total sensitivity indices S_itotS\_{i}^{tot}. Using these bounds it is possible in most cases to get a good practical estimation of the values of S_itotS\_{i}^{tot} . Several examples are used to illustrate an application of DGSM

    Profiling of the muscle-specific dystroglycan interactome reveals the role of Hippo signaling in muscular dystrophy and age-dependent muscle atrophy.

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    Dystroglycanopathies are a group of inherited disorders characterized by vast clinical and genetic heterogeneity and caused by abnormal functioning of the ECM receptor dystroglycan (Dg). Remarkably, among many cases of diagnosed dystroglycanopathies, only a small fraction can be linked directly to mutations in Dg or its regulatory enzymes, implying the involvement of other, not-yet-characterized, Dg-regulating factors. To advance disease diagnostics and develop new treatment strategies, new approaches to find dystroglycanopathy-related factors should be considered. The Dg complex is highly evolutionarily conserved; therefore, model genetic organisms provide excellent systems to address this challenge. In particular, Drosophila is amenable to experiments not feasible in any other system, allowing original insights about the functional interactors of the Dg complex. METHODS: To identify new players contributing to dystroglycanopathies, we used Drosophila as a genetic muscular dystrophy model. Using mass spectrometry, we searched for muscle-specific Dg interactors. Next, in silico analyses allowed us to determine their association with diseases and pathological conditions in humans. Using immunohistochemical, biochemical, and genetic interaction approaches followed by the detailed analysis of the muscle tissue architecture, we verified Dg interaction with some of the discovered factors. Analyses of mouse muscles and myocytes were used to test if interactions are conserved in vertebrates. RESULTS: The muscle-specific Dg complexome revealed novel components that influence the efficiency of Dg function in the muscles. We identified the closest human homologs for Dg-interacting partners, determined their significant enrichment in disease-associations, and verified some of the newly identified Dg interactions. We found that Dg associates with two components of the mechanosignaling Hippo pathway: the WW domain-containing proteins Kibra and Yorkie. Importantly, this conserved interaction manages adult muscle size and integrity. CONCLUSIONS: The results presented in this study provide a new list of muscle-specific Dg interactors, further analysis of which could aid not only in the diagnosis of muscular dystrophies, but also in the development of new therapeutics. To regulate muscle fitness during aging and disease, Dg associates with Kibra and Yorkie and acts as a transmembrane Hippo signaling receptor that transmits extracellular information to intracellular signaling cascades, regulating muscle gene expression

    Band Calculations for Ce Compounds with AuCu3_{3}-type Crystal Structure on the basis of Dynamical Mean Field Theory I. CePd3_{3} and CeRh3_{3}

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    Band calculations for Ce compounds with the AuCu3_{3}-type crystal structure were carried out on the basis of dynamical mean field theory (DMFT). The auxiliary impurity problem was solved by a method named NCAf2f^{2}vc (noncrossing approximation including the f2f^{2} state as a vertex correction). The calculations take into account the crystal-field splitting, the spin-orbit interaction, and the correct exchange process of the f1→f0,f2f^{1} \rightarrow f^{0},f^{2} virtual excitation. These are necessary features in the quantitative band theory for Ce compounds and in the calculation of their excitation spectra. The results of applying the calculation to CePd3_{3} and CeRh3_{3} are presented as the first in a series of papers. The experimental results of the photoemission spectrum (PES), the inverse PES, the angle-resolved PES, and the magnetic excitation spectra were reasonably reproduced by the first-principles DMFT band calculation. At low temperatures, the Fermi surface (FS) structure of CePd3_{3} is similar to that of the band obtained by the local density approximation. It gradually changes into a form that is similar to the FS of LaPd3_{3} as the temperature increases, since the 4f4f band shifts to the high-energy side and the lifetime broadening becomes large.}Comment: 12 pasges, 13 figure

    Derivative based global sensitivity measures

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    International audienceThe method of derivative based global sensitivity measures (DGSM) has recently become popular among practitioners. It has a strong link with the Morris screening method and Sobol' sensitivity indices and has several advantages over them. DGSM are very easy to implement and evaluate numerically. The computational time required for numerical evaluation of DGSM is generally much lower than that for estimation of Sobol' sensitivity indices. This paper presents a survey of recent advances in DGSM concerning lower and upper bounds on the values of Sobol' total sensitivity indices SitotS_{i}^{tot}. Using these bounds it is possible in most cases to get a good practical estimation of the values of SitotS_{i}^{tot} . Several examples are used to illustrate an application of DGSM

    Magneto-Gyrotropic Photogalvanic Effects in Semiconductor Quantum Wells

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    We show that free-carrier (Drude) absorption of both polarized and unpolarized terahertz radiation in quantum well (QW) structures causes an electric photocurrent in the presence of an in-plane magnetic field. Experimental and theoretical analysis evidences that the observed photocurrents are spin-dependent and related to the gyrotropy of the QWs. Microscopic models for the photogalvanic effects in QWs based on asymmetry of photoexcitation and relaxation processes are proposed. In most of the investigated structures the observed magneto-induced photocurrents are caused by spin-dependent relaxation of non-equilibrium carriers

    Theory of Spin-Resolved Auger-Electron Spectroscopy from Ferromagnetic 3d-Transition Metals

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    CVV Auger electron spectra are calculated for a multi-band Hubbard model including correlations among the valence electrons as well as correlations between core and valence electrons. The interest is focused on the ferromagnetic 3d-transition metals. The Auger line shape is calculated from a three-particle Green function. A realistic one-particle input is taken from tight-binding band-structure calculations. Within a diagrammatic approach we can distinguish between the \textit{direct} correlations among those electrons participating in the Auger process and the \textit{indirect} correlations in the rest system. The indirect correlations are treated within second-order perturbation theory for the self-energy. The direct correlations are treated using the valence-valence ladder approximation and the first-order perturbation theory with respect to valence-valence and core-valence interactions. The theory is evaluated numerically for ferromagnetic Ni. We discuss the spin-resolved quasi-particle band structure and the Auger spectra and investigate the influence of the core hole.Comment: LaTeX, 12 pages, 8 eps figures included, Phys. Rev. B (in press

    An Efficient Bi-Level Surrogate Approach for Optimizing Shock Control Bumps under Uncertainty

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    The assessment of uncertainties is essential in aerodynamic shape optimization problems in order to come up with configurations that are more robust. The influence of aleatory fluctuations in flight conditions and manufacturing tolerances is of primary concern when designing shock control bumps, as their effectiveness is highly sensitive to the shock wave location. However, exploring the stochastic design space for the global robust optimum increases the computational cost, especially when dealing with nonconvex design spaces and multiple local optima. The aim of this paper is to develop a framework for efficient aerodynamic shape optimization under uncertainty by means of a bi-level surrogate approach and to apply it to the robust design of a retrofitted shock control bump over an airfoil. The framework combines a surrogate-based optimization algorithm with an efficient surrogate-based approach for uncertainty quantification. The surrogate-based optimizer efficiently finds the global optimum of a given quantile of the drag coefficient. It outperforms traditional evolutionary algorithms by effectively balancing exploration and exploitation through the combination of adaptive sampling and a moving trust region. At each iteration of the optimization, the surrogate-based uncertainty quantification uses an active infill criterion in order to accurately quantify the quantile of the drag at a reduced number of function evaluations. Two different quantiles of the drag are chosen, the 95% to increase the robustness at off-design conditions, and the 50% for a configuration that is best for day to day operations. In both cases, the optimum configurations lead to an airfoil that is more robust to geometrical and operational uncertainties, compared to the configuration obtained through classical deterministic optimization
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