46,850 research outputs found
Multi-State Image Restoration by Transmission of Bit-Decomposed Data
We report on the restoration of gray-scale image when it is decomposed into a
binary form before transmission. We assume that a gray-scale image expressed by
a set of Q-Ising spins is first decomposed into an expression using Ising
(binary) spins by means of the threshold division, namely, we produce (Q-1)
binary Ising spins from a Q-Ising spin by the function F(\sigma_i - m) = 1 if
the input data \sigma_i \in {0,.....,Q-1} is \sigma_i \geq m and 0 otherwise,
where m \in {1,....,Q-1} is the threshold value. The effects of noise are
different from the case where the raw Q-Ising values are sent. We investigate
which is more effective to use the binary data for transmission or to send the
raw Q-Ising values. By using the mean-field model, we first analyze the
performance of our method quantitatively. Then we obtain the static and
dynamical properties of restoration using the bit-decomposed data. In order to
investigate what kind of original picture is efficiently restored by our
method, the standard image in two dimensions is simulated by the mean-field
annealing, and we compare the performance of our method with that using the
Q-Ising form. We show that our method is more efficient than the one using the
Q-Ising form when the original picture has large parts in which the nearest
neighboring pixels take close values.Comment: latex 24 pages using REVTEX, 10 figures, 4 table
A Viscoelastic model of phase separation
We show here a general model of phase separation in isotropic condensed
matter, namely, a viscoelastic model. We propose that the bulk mechanical
relaxation modulus that has so far been ignored in previous theories plays an
important role in viscoelastic phase separation in addition to the shear
relaxation modulus. In polymer solutions, for example, attractive interactions
between polymers under a poor-solvent condition likely cause the transient
gellike behavior, which makes both bulk and shear modes active. Although such
attractive interactions between molecules of the same component exist
universally in the two-phase region of a mixture, the stress arising from
attractive interactions is asymmetrically divided between the components only
in dynamically asymmetric mixtures such as polymer solutions and colloidal
suspensions. Thus, the interaction network between the slower components, which
can store the elastic energy against its deformation through bulk and shear
moduli, is formed. It is the bulk relaxation modulus associated with this
interaction network that is primarily responsible for the appearance of the
sponge structure peculiar to viscoelastic phase separation and the phase
inversion. We demonstrate that a viscoelastic model of phase separation
including this new effect is a general model that can describe all types of
isotropic phase separation including solid and fluid models as its special
cases without any exception, if there is no coupling with additional order
parameter. The physical origin of volume shrinking behavior during viscoelastic
phase separation and the universality of the resulting spongelike structure are
also discussed.Comment: 14 pages, RevTex, To appear in Phys. Rev
Orbital Symmetry and Electron Correlation in Na_{x}CoO_2
Measurements of polarization-dependent soft x-ray absorption reveal that the
electronic states determining the low-energy excitations of NaCoO
have predominantly symmetry with significant O character. A large
transfer of spectral weight observed in O x-ray absorption provides
spectral evidence for strong electron correlations in the layered cobaltates.
Comparing Co x-ray absorption with calculations based on a cluster model,
we conclude that NaCoO exhibits a charge-transfer electronic
character rather than a Mott-Hubbard character
Local electronic structure and magnetic properties of LaMn0.5Co0.5O3 studied by x-ray absorption and magnetic circular dichroism spectroscopy
We have studied the local electronic structure of LaMn0.5Co0.5O3 using
soft-x-ray absorption spectroscopy at the Co-L_3,2 and Mn-L_3,2 edges. We found
a high-spin Co^{2+}--Mn^{4+} valence state for samples with the optimal Curie
temperature. We discovered that samples with lower Curie temperatures contain
low-spin nonmagnetic Co^{3+} ions. Using soft-x-ray magnetic circular dichroism
we established that the Co^{2+} and Mn^{4+} ions are ferromagnetically aligned.
We revealed also that the Co^{2+} ions have a large orbital moment:
m_orb/m_spin ~ 0.47. Together with model calculations, this suggests the
presence of a large magnetocrystalline anisotropy in the material and predicts
a non-trivial temperature dependence for the magnetic susceptibility.Comment: 8 pages, 7 figure
Gravitational Waves from Quasi-Circular Black Hole Binaries in Dynamical Chern-Simons Gravity
Dynamical Chern-Simons gravity cannot be strongly constrained with current
experiments because it reduces to General Relativity in the weak-field limit.
This theory, however, introduces modifications in the non-linear, dynamical
regime, and thus, it could be greatly constrained with gravitational waves from
the late inspiral of black hole binaries. We complete the first self-consistent
calculation of such gravitational waves in this theory. For favorable
spin-orientations, advanced ground-based detectors may improve existing
solar-system constraints by 6 orders of magnitude.Comment: 6 pages, 1 figure; errors corrected in Eqs. (8) and (9
Extreme Blazars Studied with Fermi-LAT and Suzaku: 1ES 0347-121 and Blazar Candidate HESS J1943+213
We report on our study of high-energy properties of two peculiar TeV
emitters: the "extreme blazar" 1ES 0347-121 and the "extreme blazar candidate"
HESS J1943+213 located near the Galactic Plane. Both objects are characterized
by quiescent synchrotron emission with flat spectra extending up to the hard
X-ray range, and both were reported to be missing GeV counterparts in the
Fermi-LAT 2-year Source Catalog. We analyze a 4.5 year accumulation of the
Fermi-LAT data, resulting in the detection of 1ES 0347-121 in the GeV band, as
well as in improved upper limits for HESS J1943+213. We also present the
analysis results of newly acquired Suzaku data for HESS J1943+213. The X-ray
spectrum is well represented by a single power law extending up to 25 keV with
photon index 2.00+/-0.02 and a moderate absorption in excess of the Galactic
value, in agreement with previous X-ray observations. No short-term X-ray
variability was found over the 80 ks duration of the Suzaku exposure. Under the
blazar hypothesis, we modeled the spectral energy distributions of 1ES 0347-121
and HESS J1943+213, and derived constraints on the intergalactic magnetic field
strength and source energetics. We conclude that although the classification of
HESS J1943+213 has not yet been determined, the blazar hypothesis remains the
most plausible option, since in particular the broad-band spectra of the two
analyzed sources along with the source model parameters closely resemble each
other, and the newly available WISE and UKIDSS data for HESS J1943+213 are
consistent with the presence of an elliptical host at the distance of
approximately ~600 Mpc.Comment: 10 pages, 7 figures, 3 tables. Accepted by Ap
Semi-relativistic approximation to gravitational radiation from encounters with nonspinning black holes
The capture of compact bodies by black holes in galactic nuclei is an
important prospective source for low frequency gravitational wave detectors,
such as the planned Laser Interferometer Space Antenna. This paper calculates,
using a semirelativistic approximation, the total energy and angular momentum
lost to gravitational radiation by compact bodies on very high eccentricity
orbits passing close to a supermassive, nonspinning black hole; these
quantities determine the characteristics of the orbital evolution necessary to
estimate the capture rate. The semirelativistic approximation improves upon
treatments which use orbits at Newtonian-order and quadrupolar radiation
emission, and matches well onto accurate Teukolsky simulations for low
eccentricity orbits. Formulae are presented for the semirelativistic energy and
angular momentum fluxes as a function of general orbital parameters.Comment: 27 pages, 12 figures; v2: revised manuscript includes small changes
to make paper consistent with published version; v3: a statement about how to
generalise our results to hyperbolic orbits was incorrect, new version
includes published erratum as an appendi
Modelling the influence of foot-and-mouth disease vaccine antigen stability and dose on the bovine immune response
On the uniqueness for the spatially homogeneous Boltzmann equation with a strong angular singularity
We prove an inequality on the Wasserstein distance with quadratic cost
between two solutions of the spatially homogeneous Boltzmann equation without
angular cutoff, from which we deduce some uniqueness results. In particular, we
obtain a local (in time) well-posedness result in the case of (possibly very)
soft potentials. A global well-posedeness result is shown for all regularized
hard and soft potentials without angular cutoff. Our uniqueness result seems to
be the first one applying to a strong angular singularity, except in the
special case of Maxwell molecules.
Our proof relies on the ideas of Tanaka: we give a probabilistic
interpretation of the Boltzmann equation in terms of a stochastic process. Then
we show how to couple two such processes started with two different initial
conditions, in such a way that they almost surely remain close to each other
Valence, spin, and orbital state of the Co ions in the one-dimensional Ca3Co2O6: an x-ray absorption and magnetic circular dichroism study
We have investigated the valence, spin, and orbital state of the Co ions in
the one-dimensional cobaltate Ca3Co2O6 using x-ray absorption and x-ray
magnetic circular dichroism at the Co-L2,3 edges. The Co ions at both the
octahedral Co_oct and trigonal Co_trig sites are found to be in a 3+ state.
From the analysis of the dichroism we established a low-spin state for the
Co_oct and a high-spin state with an anomalously large orbital moment of 1.7
muB at the Co3+ trig ions. This large orbital moment along the c-axis chain and
the unusually large magnetocrystalline anisotropy can be traced back to the
double occupancy of the d2 orbital in trigonal crystal field.Comment: 5 pages, 4 figure
- âŠ