5,780 research outputs found
Fisher waves in the strong noise limit
We investigate the effects of strong number fluctuations on traveling waves
in the Fisher-Kolmogorov reaction-diffusion system. Our findings are in stark
contrast to the commonly used deterministic and weak-noise approximations. We
compute the wave velocity in one and two spatial dimensions, for which we find
a linear and a square-root dependence of the speed on the particle density.
Instead of smooth sigmoidal wave profiles, we observe fronts composed of a few
rugged kinks that diffuse, annihilate, and rarely branch; this dynamics leads
to power-law tails in the distribution of the front sizes.Comment: 4 pages, 2 figures, updat
Inductive algebras and homogeneous shifts
Inductive algebras for the irreducible unitary representations of the
universal cover of the group of unimodular two by two matrices are classified.
The classification of homogeneous shift operators is obtained as a direct
consequence. This gives a new approach to the results of Bagchi and Misra
Charge order and phase segregation in overdoped bilayer manganites
There have been recent reports of charge ordering around in the
bilayer manganites. At , there appears to be a coexistence region of
layered A-type antiferromagnetc and charge order. There are also reports of
orbital order in this region without any Jahn-Teller effect. Based on physical
grounds, this region is investigated from a model that incorporates the two
orbitals at each Mn site and a near-neighbour Coulomb repulsion. It is
shown that there indeed is both charge and orbital order close to the
half-doped region coincident with a layered magnetic structure. Although the
orbital order is known to drive the magnetic order, the layered magnetic
structure is also favoured in this system by the lack of coherent transport
across the planes and the reduced dimensionality of the lattice. The
anisotropic hopping across the orbitals and the underlying layered
structure largely determine the orbital arrangements in this region, while the
charge order is primarily due to the long range interactions.Comment: 6 pages, 6 figure
Soft X-ray resonant scattering study of single-crystal LaSrMnO
Soft X-ray resonant scattering studies at the Mn - and
the La - edges of single-crystal LaSrMnO are
reported. At low temperatures, below K, energy scans
with a fixed momentum transfer at the \emph{A}-type antiferromagnetic (0 0 1)
reflection around the Mn -edges with incident linear
and polarizations show strong resonant enhancements. The
splitting of the energy spectra around the Mn -edges may
indicate the presence of a mixed valence state, e.g., Mn/Mn. The
relative intensities of the resonance and the clear shoulder-feature as well as
the strong incident and polarization dependences strongly
indicate its complex electronic origin. Unexpected enhancement of the charge
Bragg (0 0 2) reflection at the La -edges with
polarization has been observed up to 300 K, with an anomaly appearing around
the orbital-ordering transition temperature, K,
suggesting a strong coupling (competition) between them.Comment: Accepted by European Physical Journal
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Galaxy and mass assembly: the G02 field, Herschel–ATLAS target selection and data release 3
We describe data release 3 (DR3) of the Galaxy And Mass Assembly (GAMA) survey. The GAMA survey is a spectroscopic redshift and multiwavelength photometric survey in three equatorial regions each of 60.0 deg2 (G09, G12, and G15), and two southern regions of 55.7 deg2 (G02) and 50.6 deg2 (G23). DR3 consists of: the first release of data covering the G02 region and of data on H-ATLAS (Herschel – Astrophysical Terahertz Large Area Survey) sources in the equatorial regions; and updates to data on sources released in DR2. DR3 includes 154 809 sources with secure redshifts across four regions. A subset of the G02 region is 95.5 per cent redshift complete to r < 19.8 mag over an area of 19.5 deg2, with 20 086 galaxy redshifts, that overlaps substantially with the XXL survey (X-ray) and VIPERS (redshift survey). In the equatorial regions, the main survey has even higher completeness (98.5 per cent), and spectra for about 75 per cent of H-ATLAS filler targets were also obtained. This filler sample extends spectroscopic redshifts, for probable optical counterparts to HATLAS submillimetre sources, to 0.8 mag deeper (r < 20.6 mag) than the GAMA main survey. There are 25 814 galaxy redshifts for H-ATLAS sources from the GAMA main or filler surveys. GAMA DR3 is available at the survey website (www.gama-survey.org/dr3/)
Supreme Court Voting Behavior: 1994 Term
This Article attempts, through statistical analysis, to identify the ideological leanings of the United States Supreme Court during the October 1994 Term. Although generally perceived as a conservative institution, the Court this Term adopted a more liberal stance in its approach to First Amendment, statutory civil rights, jurisdictional and federalism issues, and in litigation involving the federal government. Furthermore, in close cases that were decided by a one-Justice majority, the Court overwhelmingly adopted a more liberal result. Justice Kennedy remained the most influential Justice, his vote determining the outcome in over 80% of these close cases. While some of this liberal movement may be attributed to the nature of the agenda pursued by the Clinton administration, it is too broad-based to be discounted entirely. Regression analysis, moreover, reveals that there are several positive correlations (and one negative correlation) in the voting patterns of the five longest-tenured Justices
Magnetic excitations in stripe-ordered LaBaCuO studied using resonant inelastic x-ray scattering
The charge and spin correlations in LaBaCuO (LBCO
1/8) are studied using Cu edge resonant inelastic x-ray scattering
(RIXS). The static charge order (CO) is observed at a wavevector of
and its charge nature confirmed by measuring the dependence of this peak on the
incident x-ray polarization. The paramagnon excitation in LBCO 1/8 is then
measured as it disperses through the CO wavevector. Within the experimental
uncertainty no changes are observed in the paramagnon due to the static CO, and
the paramagnon seems to be similar to that measured in other cuprates, which
have no static CO. Given that the stripe correlation modulates both the charge
and spin degrees of freedom, it is likely that subtle changes do occur in the
paramagnon due to CO. Consequently, we propose that future RIXS measurements,
realized with higher energy resolution and sensitivity, should be performed to
test for these effects.Comment: 5 pages, 4 figure
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