20,752 research outputs found

    Towards building a conceptual framework on intermarriage

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    Increasing migration worldwide and the cultural diversity generated as a consequence of international migration has facilitated the unions of people from different countries, religions, races, and ethnicities. Such unions are often celebrated as a sign of integration; however, at the same time as they challenge people's idea of us and them, intermarriages in fact still remain controversial, and even to some extent, taboo in many societies. Research and theorizing on intermarriage is conducted predominantly in the English-speaking North American and British contexts. This special issue includes empirical studies from not only the English-speaking countries such as the U.S., Canada, and the UK, but also from Japan, Sweden, Belgium, France, and Spain and demonstrate the increasingly diverse directions taken in the study of intermarriage in regards to the patterns, experiences, and social implications of intermarriages. Moreover, the articles address the assumed link between intermarriage and “integration.

    Optimized Effective Potential Model for the Double Perovskites Sr2-xYxVMoO6 and Sr2-xYxVTcO6

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    In attempt to explore half-metallic properties of the double perovskites Sr2-xYxVMoO6 and Sr2-xYxVTcO6, we construct an effective low-energy model, which describes the behavior of the t2g-states of these compounds. All parameters of such model are derived rigorously on the basis of first-principles electronic structure calculations. In order to solve this model we employ the optimized effective potential method and treat the correlation interactions in the random phase approximation. Although correlation interactions considerably reduce the intraatomic exchange splitting in comparison with the Hartree-Fock method, this splitting still substantially exceeds the typical values obtained in the local-spin-density approximation (LSDA), which alters many predictions based on the LSDA. Our main results are summarized as follows: (i) all ferromagnetic states are expected to be half-metallic. However, their energies are generally higher than those of the ferrimagnetic ordering between V- and Mo/Tc-sites (except Sr2VMoO6); (ii) all ferrimagnetic states are metallic (except fully insulating Y2VTcO6) and no half-metallic antiferromagnetism has been found; (iii) moreover, many of the ferrimagnetic structures appear to be unstable with respect to the spin-spiral alignment. Thus, the true magnetic ground state of the most of these systems is expected to be more complex. In addition, we discuss several methodological issues related to the nonuniqueness of the effective potential for the magnetic half-metallic and insulating states.Comment: 15 pages, 9 figure

    N-Soliton Solutions to a New (2 + 1) Dimensional Integrable Equation

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    We give explicitly N-soliton solutions of a new (2 + 1) dimensional equation, ϕxt+ϕxxxz/4+ϕxϕxz+ϕxxϕz/2+x1ϕzzz/4=0\phi_{xt} + \phi_{xxxz}/4 + \phi_x \phi_{xz} + \phi_{xx} \phi_z/2 + \partial_x^{-1} \phi_{zzz}/4 = 0. This equation is obtained by unifying two directional generalization of the KdV equation, composing the closed ring with the KP equation and Bogoyavlenskii-Schiff equation. We also find the Miura transformation which yields the same ring in the corresponding modified equations.Comment: 7 pages, uses ioplppt.st

    Magnetic Properties of J-J-J' Quantum Heisenberg Chains with Spin S=1/2, 1, 3/2 and 2 in a Magnetic Field

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    By means of the density matrix renormalization group (DMRG) method, the magnetic properties of the J-J-J^{\prime} quantum Heisenberg chains with spin S=1/2S=1/2, 1, 3/2 and 2 in the ground states are investigated in the presence of a magnetic field. Two different cases are considered: (a) when JJ is antiferromagnetic and JJ^{\prime} is ferromagnetic (i.e. the AF-AF-F chain), the system is a ferrimagnet. The plateaus of the magnetization are observed. It is found that the width of the plateaus decreases with increasing the ferromagnetic coupling, and disappears when % J^{\prime}/J passes over a critical value. The saturated field is observed to be independent of the ferromagnetic coupling; (b) when JJ is ferromagnetic and JJ^{\prime} is antiferromagnetic (i.e. the F-F-AF chain), the system becomes an antiferromagnet. The plateaus of the magnetization are also seen. The width of the plateaus decreases with decreasing the antiferromagnetic coupling, and disappears when J/JJ^{\prime}/J passes over a critical value. Though the ground state properties are quite different, the magnetization plateaus in both cases tend to disappear when the ferromagnetic coupling becomes more dominant. Besides, no fundamental difference between the systems with spin half-integer and integer has been found.Comment: 8 pages, 9 figures, to be published in J. Phys.: Condens. Matte

    slq(2)sl_q(2) Realizations for Kepler and Oscillator Potentials and q-Canonical Transformations

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    The realizations of the Lie algebra corresponding to the dynamical symmetry group SO(2,1) of the Kepler and oscillator potentials are q-deformed. The q-canonical transformation connecting two realizations is given and a general definition for q-canonical transformation is deduced. q-Schr\"{o}dinger equation for a Kepler like potential is obtained from the q-oscillator Schr\"{o}dinger equation. Energy spectrum and the ground state wave function are calculated.Comment: 12 pages, Latex twice, (Comparison with the other approaches and some refs. added. The version which will appear in J. Phys. A

    OPT3 is a component of the iron-signaling network between leaves and roots and misregulation of OPT3 leads to an over-accumulation of cadmium in seeds.

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    Plants and seeds are the main dietary sources of zinc, iron, manganese, and copper, but are also the main entry point for toxic elements such as cadmium into the food chain. We report here that an Arabidopsis oligopeptide transporter mutant, opt3-2, over-accumulates cadmium (Cd) in seeds and roots but, unexpectedly, under-accumulates Cd in leaves. The cadmium distribution in opt3-2 differs from iron, zinc, and manganese, suggesting a metal-specific mechanism for metal partitioning within the plant. The opt3-2 mutant constitutively up-regulates the Fe/Zn/Cd transporter IRT1 and FRO2 in roots, indicative of an iron-deficiency response. No genetic mutants that impair the shoot-to-root signaling of iron status in leaves have been identified. Interestingly, shoot-specific expression of OPT3 rescues the Cd sensitivity and complements the aberrant expression of IRT1 in opt3-2 roots, suggesting that OPT3 is required to relay the iron status from leaves to roots. OPT3 expression was found in the vasculature with preferential expression in the phloem at the plasma membrane. Using radioisotope experiments, we found that mobilization of Fe from leaves is severely affected in opt3-2, suggesting that Fe mobilization out of leaves is required for proper trace-metal homeostasis. When expressed in yeast, OPT3 does not localize to the plasma membrane, precluding the identification of the OPT3 substrate. Our in planta results show that OPT3 is important for leaf phloem-loading of iron and plays a key role regulating Fe, Zn, and Cd distribution within the plant. Furthermore, ferric chelate reductase activity analyses provide evidence that iron is not the sole signal transferred from leaves to roots in leaf iron status signaling

    A novel STFT implementation for the analysis of non-stationary jammer interference

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    A novel adaptive short-time Fourier transform (STFT) implementation for the analysis of non-stationary multi-component jammer signals is introduced. The proposed time-frequency distribution is the fusion of optimum STFTs of individual signal components that are based on the recently introduced generalized time-bandwidth product (GTBP) definition. The GTBP optimal STFTs of the components are combined through thresholding and obtaining the individual component support images, which are related with the corresponding GTBP optimal STFTs

    The VAST Survey - IV. A wide brown dwarf companion to the A3V star ζ\zeta Delphini

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    We report the discovery of a wide co-moving substellar companion to the nearby (D=67.5±1.1D=67.5\pm1.1 pc) A3V star ζ\zeta Delphini based on imaging and follow-up spectroscopic observations obtained during the course of our Volume-limited A-Star (VAST) multiplicity survey. ζ\zeta Del was observed over a five-year baseline with adaptive optics, revealing the presence of a previously-unresolved companion with a proper motion consistent with that of the A-type primary. The age of the ζ\zeta Del system was estimated as 525±125525\pm125 Myr based on the position of the primary on the colour-magnitude and temperature-luminosity diagrams. Using intermediate-resolution near-infrared spectroscopy, the spectrum of ζ\zeta Del B is shown to be consistent with a mid-L dwarf (L5±25\pm2), at a temperature of 1650±2001650\pm200 K. Combining the measured near-infrared magnitude of ζ\zeta Del B with the estimated temperature leads to a model-dependent mass estimate of 50±1550\pm15 MJup_{\rm Jup}, corresponding to a mass ratio of q=0.019±0.006q=0.019\pm0.006. At a projected separation of 910±14910\pm14 au, ζ\zeta Del B is among the most widely-separated and extreme-mass ratio substellar companions to a main-sequence star resolved to-date, providing a rare empirical constraint of the formation of low-mass ratio companions at extremely wide separations.Comment: 12 pages, 11 figures, accepted for publication in the Monthly Notices of the Royal Astronomical Society, 2014 September 25. Revised to incorporate typographical errors noted during the proofing proces

    Differential-difference system related to toroidal Lie algebra

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    We present a novel differential-difference system in (2+1)-dimensional space-time (one discrete, two continuum), arisen from the Bogoyavlensky's (2+1)-dimensional KdV hierarchy. Our method is based on the bilinear identity of the hierarchy, which is related to the vertex operator representation of the toroidal Lie algebra \sl_2^{tor}.Comment: 10 pages, 4 figures, pLaTeX2e, uses amsmath, amssymb, amsthm, graphic
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