44,977 research outputs found

    Local spatiotemporal modeling of house prices: a mixed model approach

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    The real estate market has long provided an active application area for spatial–temporal modeling and analysis and it is well known that house prices tend to be not only spatially but also temporally correlated. In the spatial dimension, nearby properties tend to have similar values because they share similar characteristics, but house prices tend to vary over space due to differences in these characteristics. In the temporal dimension, current house prices tend to be based on property values from previous years and in the spatial–temporal dimension, the properties on which current prices are based tend to be in close spatial proximity. To date, however, most research on house prices has adopted either a spatial perspective or a temporal one; relatively little effort has been devoted to situations where both spatial and temporal effects coexist. Using ten years of house price data in Fife, Scotland (2003–2012), this research applies a mixed model approach, semiparametric geographically weighted regression (GWR), to explore, model, and analyze the spatiotemporal variations in the relationships between house prices and associated determinants. The study demonstrates that the mixed modeling technique provides better results than standard approaches to predicting house prices by accounting for spatiotemporal relationships at both global and local scales

    Integrable Systems in n-dimensional Riemannian Geometry

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    In this paper we show that if one writes down the structure equations for the evolution of a curve embedded in an (n)-dimensional Riemannian manifold with constant curvature this leads to a symplectic, a Hamiltonian and an hereditary operator. This gives us a natural connection between finite dimensional geometry, infinite dimensional geometry and integrable systems. Moreover one finds a Lax pair in (\orth{n+1}) with the vector modified Korteweg-De Vries equation (vmKDV) \vk{t}= \vk{xxx}+\fr32 ||\vk{}||^2 \vk{x} as integrability condition. We indicate that other integrable vector evolution equations can be found by using a different Ansatz on the form of the Lax pair. We obtain these results by using the {\em natural} or {\em parallel} frame and we show how this can be gauged by a generalized Hasimoto transformation to the (usual) {\em Fren{\^e}t} frame. If one chooses the curvature to be zero, as is usual in the context of integrable systems, then one loses information unless one works in the natural frame

    Eigenstates of Paraparticle Creation Operators

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    Eigenstates of the parabose and parafermi creation operators are constructed. In the Dirac contour representation, the parabose eigenstates correspond to the dual vectors of the parabose coherent states. In order p=2p=2, conserved-charge parabose creation operator eigenstates are also constructed. The contour forms of the associated resolutions of unity are obtained.Comment: 14 pages, LaTex file, no macros, no figure

    The Evolution of Comparative Advantage: Measurement and Welfare Implications

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    Using an industry-level dataset of production and trade spanning 75 countries and 5 decades, and a fully speciÞed multi-sector Ricardian model, we estimate productivities at sector level and examine how they evolve over time in both developed and developing countries. We find that in both country groups, comparative advantage has become weaker: productivity grew systematically faster in sectors that were initially at the greater comparative disadvantage. The global welfare implications of this phenomenon are significant. Relative to the counterfactual scenario in which an individual countryÕs comparative advantage remained the same as in the 1960s, and technology in all sectors grew at the same country-specific average rate, welfare today is 1.9% lower at the median. The welfare impact varies greatly across countries, ranging from -0.5% to 6% among OECD countries, and from -9% to 27% among non-OECD countries. Remarkably, for the OECD countries, nearly all of the welfare impact is driven by changes in technology in OECD countries, and for the non-OECD countries, nearly all of the welfare impact is driven by changes in technology in non-OECD countries.evolution of comparative advantage, welfare, Ricardian models of trade

    Confinement induced by fermion damping in three-dimensional QED

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    The three-dimensional non-compact QED is known to exhibit weak confinement when fermions acquire a finite mass via the mechanism of dynamical chiral symmetry breaking. In this paper, we study the effect of fermion damping caused by elastic scattering on the classical potential between fermions. By calculating the vacuum polarization function that incorporates the fermion damping effect, we show that fermion damping can induce a weak confinement even when the fermions are massless and the chiral symmetry is not broken.Comment: 4 pages, no figur

    Nonlinear force-free field modeling of a solar active region using SDO/HMI and SOLIS/VSM data

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    We use SDO/HMI and SOLIS/VSM photospheric magnetic field measurements to model the force-free coronal field above a solar active region, assuming magnetic forces to dominate. We take measurement uncertainties caused by, e.g., noise and the particular inversion technique into account. After searching for the optimum modeling parameters for the particular data sets, we compare the resulting nonlinear force-free model fields. We show the degree of agreement of the coronal field reconstructions from the different data sources by comparing the relative free energy content, the vertical distribution of the magnetic pressure and the vertically integrated current density. Though the longitudinal and transverse magnetic flux measured by the VSM and HMI is clearly different, we find considerable similarities in the modeled fields. This indicates the robustness of the algorithm we use to calculate the nonlinear force-free fields against differences and deficiencies of the photospheric vector maps used as an input. We also depict how much the absolute values of the total force-free, virial and the free magnetic energy differ and how the orientation of the longitudinal and transverse components of the HMI- and VSM-based model volumes compares to each other.Comment: 9 pages, 5 figure

    AGRICULTURAL PRODUCTIVITY GROWTH IN CHINA: FARM LEVEL VERSUS NATIONAL MEASUREMENT

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    agricultural productivity, China, Productivity Analysis,

    Maximal violation of Clauser-Horne-Shimony-Holt inequality for four-level systems

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    Clauser-Horne-Shimony-Holt inequality for bipartite systems of 4-dimension is studied in detail by employing the unbiased eight-port beam splitters measurements. The uniform formulae for the maximum and minimum values of this inequality for such measurements are obtained. Based on these formulae, we show that an optimal non-maximally entangled state is about 6% more resistant to noise than the maximally entangled one. We also give the optimal state and the optimal angles which are important for experimental realization.Comment: 7 pages, three table

    Full one-loop electroweak corrections to h0(H0,A0)H±Wh^0(H^0,A^0) H^\pm W^\mp associated productions at e+ee^+e^- linear colliders

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    We study the complete one-loop electroweak(EW) corrections to the processes of single charged Higgs boson production associated with a neutral Higgs boson(h0,H0,A0)(h^0,H^0,A^0) and a gauge boson W±W^\pm in the framework of the minimal supersymmetric standard model(MSSM). Numerical results at the SPS1a{\rm SPS1a'} benchmark point as proposed in the SPA project, are presented for demonstration. We find that for the process e+eh0H±We^+e^-\to h^0H^\pm W^\mp the EW relative correction can be either positive or negative and in the range of 15-15%\sim 20% in our chosen parameter space. While for the processes e+eH0(A0)H±We^+e^-\to H^0(A^0)H^\pm W^\mp the corrections generally reduce the Born cross sections and the EW relative corrections are typically of order 1020-10%\sim -20%.Comment: 22 pages, 20 figures, LaTex, to be appeared in PR
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