44,977 research outputs found
Local spatiotemporal modeling of house prices: a mixed model approach
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
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
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 , 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
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
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
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
agricultural productivity, China, Productivity Analysis,
Maximal violation of Clauser-Horne-Shimony-Holt inequality for four-level systems
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 associated productions at linear colliders
We study the complete one-loop electroweak(EW) corrections to the processes
of single charged Higgs boson production associated with a neutral Higgs
boson and a gauge boson in the framework of the minimal
supersymmetric standard model(MSSM). Numerical results at the
benchmark point as proposed in the SPA project, are presented for
demonstration. We find that for the process the EW
relative correction can be either positive or negative and in the range of
in our chosen parameter space. While for the processes
the corrections generally reduce the Born cross
sections and the EW relative corrections are typically of order .Comment: 22 pages, 20 figures, LaTex, to be appeared in PR
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