26,305 research outputs found
Probing the role of single defects on the thermodynamics of electric-field induced phase transitions
The kinetics and thermodynamics of first order transitions is universally
controlled by defects that act as nucleation sites and pinning centers. Here we
demonstrate that defect-domain interactions during polarization reversal
processes in ferroelectric materials result in a pronounced fine structure in
electromechanical hysteresis loops. Spatially-resolved imaging of a single
defect center in multiferroic BiFeO3 thin film is achieved, and the defect size
and built-in field are determined self-consistently from the single-point
spectroscopic measurements and spatially-resolved images. This methodology is
universal and can be applied to other reversible bias-induced transitions
including electrochemical reactions.Comment: 34 pages,4 figures, high quality figures are available upon request,
submitted to Phys. Rev. Let
Polycyclic Aromatic Hydrocarbons and Polychlorinated Biphenyl Contamination in DaTong City, China
One-Loop Effect of Null-Like Cosmology's Holographic Dual Super-Yang-Mills
We calculate the 1-loop effect in super-Yang-Mills which preserves
1/4-supersymmetries and is holographically dual to the null-like cosmology with
a big-bang singularity. Though the bosonic and fermionic spectra do not agree
precisely, we do obtain vanishing 1-loop vacuum energy for generic warped
plane-wave type backgrounds with a big-bang singularity. Moreover, we find that
the cosmological "constant" contributed either by bosons or fermions is
time-dependent. The issues about the particle production of some background and
about the UV structure are also commented. We argue that the effective higher
derivative interactions are suppressed as long as the Fourier transform of the
time-dependent coupling is UV-finite. Our result holds for scalar
configurations that are BPS but with arbitrary time-dependence. This suggests
the existence of non-renormalization theorem for such a new class of
time-dependent theories. Altogether, it implies that such a super-Yang-Mills is
scale-invariant, and that its dual bulk quantum gravity might behave regularly
near the big bang.Comment: 20 pages, v2 add comments and references, v3 clarify BPS condition &
add new discussion on particle production and UV structure, v4&v5 minor
changes, final to JHE
Chiral primary cubic interactions from pp-wave supergravity
We explicitly construct cubic interaction light-cone Hamiltonian for the
chiral primary system involving the metric fields and the self-dual four-form
fields in the IIB pp-wave supergravity. The background fields representing
pp-waves exhibit SO(4)*SO(4)*Z_2 invariance. It turns out that the interaction
Hamiltonian is precisely the same as that for the dilaton-axion system, except
for the fact that the chiral primary system fields have the opposite parity to
that of the dilaton-axion fields under the Z_2 transformation that exchanges
two SO(4)'s.Comment: 14 pages, A few comments are adde
The Bell Laboratories (13)CO Survey: Longitude-Velocity Maps
A survey is presented of the Galactic plane in the J=1-0 transition of
(13)CO. About 73,000 spectra were obtained with the 7 m telescope at Bell
Laboratories over a ten-year period. The coverage of survey is (l, b) = (-5 to
117, -1 to +1), or 244 square degrees, with a grid spacing of 3' for |b| < 0.5,
and a grid spacing of 6' for |b| > 0.5. The data presented here have been
resampled onto a 3' grid. For 0.68 km/s channels, the rms noise level of the
survey is 0.1 K on the scale. The raw data have been transformed into
FITS format, and all the reduction processes, such as correcting for emission
in the reference positions, baseline removal and interpolation were conducted
within IRAF using the FCRAO task package and additional programs. The reduced
data are presented here in the form of longitude-velocity color maps at each
latitude. These data allow identification and classification of molecular
clouds with masses in excess of ~ 1,000 solar masses throughout the first
quadrant of the Galaxy. Spiral structure is manifested by the locations of the
largest and brightest molecular clouds.Comment: 23 pages, 7 figures, ApJS submitted (out of 41 frames of Figure4,
only one is included becaue of size limit
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