40,843 research outputs found
Edge coating of flat wires
An apparatus and technique is described for the coating of the edge surfaces of flat ribbon conductors with an adherent coating of a dielectric insulating material. Means for passing the ribbon conductors between a pair of generally axially aligned rollers is provided. The edge surfaces of the conductor are disposed adjacent to and generally tangentially to the confronting surfaces of the roller so as to form a fillet of dielectric material along the edge surface of the conductor
Bering's proposal for boundary contribution to the Poisson bracket
It is shown that the Poisson bracket with boundary terms recently proposed by
Bering (hep-th/9806249) can be deduced from the Poisson bracket proposed by the
present author (hep-th/9305133) if one omits terms free of Euler-Lagrange
derivatives ("annihilation principle"). This corresponds to another definition
of the formal product of distributions (or, saying it in other words, to
another definition of the pairing between 1-forms and 1-vectors in the formal
variational calculus). We extend the formula (initially suggested by Bering
only for the ultralocal case with constant coefficients) onto the general
non-ultralocal brackets with coefficients depending on fields and their spatial
derivatives. The lack of invariance under changes of dependent variables (field
redefinitions) seems a drawback of this proposal.Comment: 18 pages, LaTeX, amssym
Listing Specialization and Residential Real Estate Licensee
Earlier research has found that specialization by real estate agents creates economies of scope for real estate firms. So far, however, no research has addressed this issue at the agent level. The question this research seeks to answer is whether specialization in one side of the real estate transaction increases agent income. The most important finding is that specialization has an asymmetric impact on earnings. Specializing in listings positively enhances agent income. In contrast, specialization on the selling side has an adverse affect on agent income. The implications of these findings for the consumer and real estate industry are also examined.
X-Inefficiencies in the Residential Real Estate Market: A Stochastic Frontier Approach
This article examines the productive efficiency levels present in the market for residential real estate brokerage services by employing the stochastic frontier approach. The only prior study (Anderson, Zumpano, Elder and Fok, 1998) that examined productive efficiency in this sector employed data envelopment analysis. This current article addresses potential statistical limitations of Data Envelopment Analysis and uses an alternative statistical tool, the stochastic frontier approach, to estimate X-efficiencies. This technique overcomes many of the statistical limitations of DEA and provides additional productive efficiency estimates. The results suggest that residential real estate brokerage firms are relatively efficient, in contrast to the earlier study that found significant inefficiencies present in this market. Firms could only reduce their average total costs by 12% given firm outputs and input prices. Additionally, the firms were divided into three size categories to examine the impact of firm size on efficiency. The results indicate that small firms are the most efficient group. Hence, there seems to be a tradeoff between scale efficiency and productive efficiency.
Spread of Infectious Diseases with a Latent Period
Infectious diseases spread through human networks.
Susceptible-Infected-Removed (SIR) model is one of the epidemic models to
describe infection dynamics on a complex network connecting individuals. In the
metapopulation SIR model, each node represents a population (group) which has
many individuals. In this paper, we propose a modified metapopulation SIR model
in which a latent period is taken into account. We call it SIIR model. We
divide the infection period into two stages: an infected stage, which is the
same as the previous model, and a seriously ill stage, in which individuals are
infected and cannot move to the other populations. The two infectious stages in
our modified metapopulation SIR model produce a discontinuous final size
distribution. Individuals in the infected stage spread the disease like
individuals in the seriously ill stage and never recover directly, which makes
an effective recovery rate smaller than the given recovery rate.Comment: 6 pages, 3 figure
Comment on 'Quantum Backreaction on "Classical" Variables'
It is argued that the bracket of Anderson's canonical theory should have been
antisymmetric otherwise serious controversies arise like violation of both
hermiticity and the Leibniz rule of differentiation.Comment: 3 pages, LaTe
Condensate splitting in an asymmetric double well for atom chip based sensors
We report on the adiabatic splitting of a BEC of Rb atoms by an
asymmetric double-well potential located above the edge of a perpendicularly
magnetized TbGdFeCo film atom chip. By controlling the barrier height and
double-well asymmetry the sensitivity of the axial splitting process is
investigated through observation of the fractional atom distribution between
the left and right wells. This process constitutes a novel sensor for which we
infer a single shot sensitivity to gravity fields of . From a simple analytic model we propose improvements
to chip-based gravity detectors using this demonstrated methodology.Comment: 4 pages, 5 figure
Quantum tunneling between paramagnetic and superconducting states of a nanometer-scale superconducting grain placed in a magnetic field
We consider the process of quantum tunneling between the superconducting and
paramagnetic states of a nanometer-scale superconducting grain placed in a
magnetic field. The grain is supposed to be coupled via tunneling junction to a
normal metallic contact that plays a role of the spin reservoir. Using the
instanton method we find the probability of the quantum tunneling process and
express it in terms of the applied magnetic field, order parameter of the
superconducting grain and conductance of the tunneling junction between the
grain and metallic contact
Oscillatory decay of a two-component Bose-Einstein condensate
We study the decay of a two-component Bose-Einstein condensate with negative
effective interaction energy. With a decreasing atom number due to losses, the
atom-atom interaction becomes less important and the system undergoes a
transition from a bistable Josephson regime to the monostable Rabi regime,
displaying oscillations in phase and number. We study the equations of motion
and derive an analytical expression for the oscillation amplitude. A quantum
trajectory simulation reveals that the classical description fails for low
emission rates, as expected from analytical considerations. Observation of the
proposed effect will provide evidence for negative effective interaction.Comment: 4 pages, 3 figue
Triplet pairing due to spin-orbit-assisted electron-phonon coupling
We propose a microscopic mechanism for triplet pairing due to
spin-orbit-assisted electron interaction with optical phonons in a crystal with
a complex unit cell. Using two examples of electrons with symmetric Fermi
surfaces in crystals with either a cubic or a layered square lattice, we show
that spin-orbit-assisted electron-phonon coupling can, indeed, generate triplet
pairing and that, in each case, it predetermines the tensor structure of a
p-wave order parameter
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