3,218 research outputs found
SAGE 1 data user's guide
A guide for using the data products from the Stratospheric Aerosol and Gas Experiment 1 (SAGE 1) for scientific investigations of stratospheric chemistry related to aerosol, ozone, nitrogen dioxide, dynamics, and climate change is presented. A detailed description of the aerosol profile tape, the ozone profile tape, and the nitrogen dioxide profile tape is included. These tapes are the SAGE 1 data products containing aerosol extinction data and ozone and nitrogen dioxide concentration data for use in the different scientific investigations. Brief descriptions of the instrument operation, data collection, processing, and validation, and some of the scientific analyses that were conducted are also included
Efficient Hadronic Operators in Lattice Gauge Theory
We study operators to create hadronic states made of light quarks in quenched
lattice gauge theory. We construct non-local gauge-invariant operators which
provide information about the spatial extent of the ground state and excited
states. The efficiency of the operators is shown by looking at the wave
function of the first excited state, which has a node as a function of the
spatial extent of the operator. This allows one to obtain an uncontaminated
ground state for hadrons.Comment: 18 pages, Latex text, followed by 11 postscript figures in
self-unpacking file. Also available at
ftp://suna.amtp.liv.ac.uk/pub/cmi/wavefn
High-accuracy waveforms for binary black hole inspiral, merger, and ringdown
The first spectral numerical simulations of 16 orbits, merger, and ringdown
of an equal-mass non-spinning binary black hole system are presented.
Gravitational waveforms from these simulations have accumulated numerical phase
errors through ringdown of ~0.1 radian when measured from the beginning of the
simulation, and ~0.02 radian when waveforms are time and phase shifted to agree
at the peak amplitude. The waveform seen by an observer at infinity is
determined from waveforms computed at finite radii by an extrapolation process
accurate to ~0.01 radian in phase. The phase difference between this waveform
at infinity and the waveform measured at a finite radius of r=100M is about
half a radian. The ratio of final mass to initial mass is M_f/M = 0.95162 +-
0.00002, and the final black hole spin is S_f/M_f^2=0.68646 +- 0.00004.Comment: 15 pages, 11 figures; New figure added, text edited to improve
clarity, waveform made availabl
Accuracy of binary black hole waveform models for aligned-spin binaries
Coalescing binary black holes are among the primary science targets for
second generation ground-based gravitational wave (GW) detectors. Reliable GW
models are central to detection of such systems and subsequent parameter
estimation. This paper performs a comprehensive analysis of the accuracy of
recent waveform models for binary black holes with aligned spins, utilizing a
new set of high-accuracy numerical relativity simulations. Our analysis
covers comparable mass binaries (), and samples
independently both black hole spins up to dimensionless spin-magnitude of
for equal-mass binaries and for unequal mass binaries. Furthermore, we
focus on the high-mass regime (total mass ). The two most
recent waveform models considered (PhenomD and SEOBNRv2) both perform very well
for signal detection, losing less than 0.5\% of the recoverable signal-to-noise
ratio , except that SEOBNRv2's efficiency drops mildly for both black
hole spins aligned with large magnitude. For parameter estimation, modeling
inaccuracies of SEOBNRv2 are found to be smaller than systematic uncertainties
for moderately strong GW events up to roughly . PhenomD's
modeling errors are found to be smaller than SEOBNRv2's, and are generally
irrelevant for . Both models' accuracy deteriorates with
increased mass-ratio, and when at least one black hole spin is large and
aligned. The SEOBNRv2 model shows a pronounced disagreement with the numerical
relativity simulation in the merger phase, for unequal masses and
simultaneously both black hole spins very large and aligned. Two older waveform
models (PhenomC and SEOBNRv1) are found to be distinctly less accurate than the
more recent PhenomD and SEOBNRv2 models. Finally, we quantify the bias expected
from all GW models during parameter estimation for recovery of binary's masses
and spins.Comment: 24 pages, 15 figures, minor change
On the accuracy and precision of numerical waveforms: Effect of waveform extraction methodology
We present a new set of 95 numerical relativity simulations of non-precessing
binary black holes (BBHs). The simulations sample comprehensively both
black-hole spins up to spin magnitude of 0.9, and cover mass ratios 1 to 3. The
simulations cover on average 24 inspiral orbits, plus merger and ringdown, with
low initial orbital eccentricities . A subset of the simulations
extends the coverage of non-spinning BBHs up to mass ratio .
Gravitational waveforms at asymptotic infinity are computed with two
independent techniques, extrapolation, and Cauchy characteristic extraction. An
error analysis based on noise-weighted inner products is performed. We find
that numerical truncation error, error due to gravitational wave extraction,
and errors due to the finite length of the numerical waveforms are of similar
magnitude, with gravitational wave extraction errors somewhat dominating at
noise-weighted mismatches of . This set of waveforms will
serve to validate and improve aligned-spin waveform models for gravitational
wave science.Comment: 22 pages, 9 figure
Testing morphodynamic controls on the location and frequency of river avulsions on fans versus deltas: Huanghe (Yellow River), China
A mechanistic understanding of river avulsion location and frequency is needed to predict the growth of alluvial fans and deltas. The Huanghe, China, provides a rare opportunity to test emerging theories because its high sediment load produces regular avulsions at two distinct nodes. Where the river debouches from the Loess plateau, avulsions occur at an abrupt decrease in bed slope and reoccur at a time interval (607 yrs) consistent with a channel-filling timescale set by the superelevation height of the levees. Downstream, natural deltaic avulsions reoccur at a timescale that is fast (7 yrs) compared to channel-filling timescale due to large stage-height variability during floods. Unlike the upstream node, deltaic avulsions cluster at a location influenced by backwater hydrodynamics and show evidence for episodic downstream migration in concert with progradation of the shoreline, providing new expectations for the interplay between avulsion location, frequency, shoreline rugosity and delta morphology
The Fading Radio Emission from SN 1961V: Evidence for a Type II Peculiar Supernova?
Using the Very Large Array (VLA), we have detected radio emission from the
site of SN 1961V in the Sc galaxy NGC 1058. With a peak flux density of 0.063
+/- 0.008 mJy/beam at 6 cm and 0.147 +/- 0.026 mJy/beam at 18 cm, the source is
non-thermal, with a spectral index of -0.79 +/- 0.23. Within errors, this
spectral index is the same value reported for previous VLA observations taken
in 1984 and 1986. The radio emission at both wavelengths has decayed since the
mid 1980's observations with power-law indices of beta(20cm) = -0.69 +/- 0.23
and beta(6cm) = -1.75 +/- 0.16. We discuss the radio properties of this source
and compare them with those of Type II radio supernovae and luminous blue
variables.Comment: 19 pages, 3 figures; To appear in the Astronomical Journa
Phenotypic Behavior of Caveolin-3 Mutations That Cause Autosomal Dominant Limb Girdle Muscular Dystrophy (LGMD-1C) RETENTION OF LGMD-1C CAVEOLIN-3 MUTANTS WITHIN THE GOLGI COMPLEX
Caveolin-3, a muscle-specific caveolin-related protein, is the principal structural protein of caveolae membrane domains in striated muscle cell types (cardiac and skeletal). Autosomal dominant limb girdle muscular dystrophy (LGMD-1C) in humans is due to mutations within the caveolin-3 gene: (i) a 9-base pair microdeletion that removes three amino acids within the caveolin scaffolding domain (DeltaTFT) or (ii) a missense mutation within the membrane spanning domain (P --> L). The molecular mechanisms by which these two mutations cause muscular dystrophy remain unknown. Here, we investigate the phenotypic behavior of these caveolin-3 mutations using heterologous expression. Wild type caveolin-3 or caveolin-3 mutants were transiently expressed in NIH 3T3 cells. LGMD-1C mutants of caveolin-3 (DeltaTFT or P --> L) were primarily retained at the level of a perinuclear compartment that we identified as the Golgi complex in double-labeling experiments, while wild type caveolin-3 was efficiently targeted to the plasma membrane. In accordance with these observations, caveolin-3 mutants formed oligomers of a much larger size than wild type caveolin-3 and were excluded from caveolae-enriched membrane fractions as seen by sucrose density gradient centrifugation. In addition, these caveolin-3 mutants were expressed at significantly lower levels and had a dramatically shortened half-life of approximately 45-60 min. However, caveolin-3 mutants were palmitoylated to the same extent as wild type caveolin-3, indicating that targeting to the plasma membrane is not required for palmitoylation of caveolin-3. In conclusion, we show that LGMD-1C mutations lead to formation of unstable high molecular mass aggregates of caveolin-3 that are retained within the Golgi complex and are not targeted to the plasma membrane. Consistent with its autosomal dominant form of genetic transmission, we demonstrate that LGMD-1C mutants of caveolin-3 behave in a dominant-negative fashion, causing the retention of wild type caveolin-3 at the level of the Golgi. These data provide a molecular explanation for why caveolin-3 levels are down-regulated in patients with this form of limb girdle muscular dystrophy (LGMD-1C)
Prototype effective-one-body model for nonprecessing spinning inspiral-merger-ringdown waveforms
We first use five non-spinning and two mildly spinning (chi_i \simeq -0.44,
+0.44) numerical-relativity waveforms of black-hole binaries and calibrate an
effective-one-body (EOB) model for non-precessing spinning binaries, notably
its dynamics and the dominant (2,2) gravitational-wave mode. Then, we combine
the above results with recent outcomes of small-mass-ratio simulations produced
by the Teukolsky equation and build a prototype EOB model for detection
purposes, which is capable of generating inspiral-merger-ringdown waveforms for
non-precessing spinning black-hole binaries with any mass ratio and individual
black-hole spins -1 \leq chi_i \lesssim 0.7. We compare the prototype EOB model
to two equal-mass highly spinning numerical-relativity waveforms of black holes
with spins chi_i = -0.95, +0.97, which were not available at the time the EOB
model was calibrated. In the case of Advanced LIGO we find that the mismatch
between prototype-EOB and numerical-relativity waveforms is always smaller than
0.003 for total mass 20-200 M_\odot, the mismatch being computed by maximizing
only over the initial phase and time. To successfully generate merger waveforms
for individual black-hole spins chi_i \gtrsim 0.7, the prototype-EOB model
needs to be improved by (i) better modeling the plunge dynamics and (ii)
including higher-order PN spin terms in the gravitational-wave modes and
radiation-reaction force.Comment: 20 pages, 8 figures. Minor changes to match version accepted for
publication in PR
Gauge invariant structures and Confinement
By looking at cooled configurations on the lattice, we study the presence of
peaks in the action density, or its electric and magnetic components, in the
SU(2) gauge vacuum. The peaks are seen to be of instanton-like nature and their
number variation takes care of the drop in the string tension observed when
cooling. Possible explanations of this finding are analysed.Comment: uuencoded and compressed file of the Postcript file newpaper.ps,
fig1.ps,fig2.eps,fig3.ps and fig4.ps. 13 pages of text and 4 figures Style
modifications and misprints correcte
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