86,175 research outputs found
Coding theorems for turbo code ensembles
This paper is devoted to a Shannon-theoretic study of turbo codes. We prove that ensembles of parallel and serial turbo codes are "good" in the following sense. For a turbo code ensemble defined by a fixed set of component codes (subject only to mild necessary restrictions), there exists a positive number γ0 such that for any binary-input memoryless channel whose Bhattacharyya noise parameter is less than γ0, the average maximum-likelihood (ML) decoder block error probability approaches zero, at least as fast as n -β, where β is the "interleaver gain" exponent defined by Benedetto et al. in 1996
p-wave Feshbach molecules
We have produced and detected molecules using a p-wave Feshbach resonance
between 40K atoms. We have measured the binding energy and lifetime for these
molecules and we find that the binding energy scales approximately linearly
with magnetic field near the resonance. The lifetime of bound p-wave molecules
is measured to be 1.0 +/- 0.1 ms and 2.3 +/- 0.2 ms for the m_l = +/- 1 and m_l
= 0 angular momentum projections, respectively. At magnetic fields above the
resonance, we detect quasi-bound molecules whose lifetime is set by the
tunneling rate through the centrifugal barrier
Highly Ionised Gas as a Diagnostic of the Inner NLR
The spectra of AGN from the ultraviolet to the near infrared, exhibit
emission lines covering a wide range of ionisation states, from neutral species
such as [O I] 6300A, up to [Fe XIV] 5303A. Here we report on some recent
studies of the properties of highly ionised lines (HILs), plus two case studies
of individual objects. Future IFU observations at high spatial and good
spectral resolution, will probe the excitation and kinematics of the gas in the
zone between the extended NLR and unresolved BLR. Multi-component SED fitting
can be used to link the source of photoionisation with the strengths and ratios
of the HILs.Comment: Proceedings of the IAU Symposium: Co-evolution of Central Black Holes
and Galaxie
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Impacts of model calibration on high-latitude land-surface processes: PILPS 2(e) calibration/validation experiments
In the PILPS 2(e) experiment, the Snow Atmosphere Soil Transfer (SAST) land-surface scheme developed from the Biosphere-Atmosphere Transfer Scheme (BATS) showed difficulty in accurately simulating the patterns and quantities of runoff resulting from heavy snowmelt in the high-latitude Torne-Kalix River basin (shared by Sweden and Finland). This difficulty exposes the model deficiency in runoff formations. After representing subsurface runoff and calibrating the parameters, the accuracy of hydrograph prediction improved substantially. However, even with the accurate precipitation and runoff, the predicted soil moisture and its variation were highly "model-dependent". Knowledge obtained from the experiment is discussed. © 2003 Elsevier Science B.V. All rights reserved
Higher Criticism Statistic: Detecting and Identifying Non-Gaussianity in the WMAP First Year Data
Higher Criticism is a recently developed statistic for non-Gaussian
detection, proposed in Donoho & Jin 2004. We find that Higher Criticism is
useful for two purposes. First, Higher Criticism has competitive detection
power, and non-Gaussianity is detected at the level 99% in the first year WMAP
data. We find that the Higher Criticism value of WMAP is outside the 99%
confidence region at a wavelet scale of 5 degrees (99.46% of Higher Criticism
values based on simulated maps are below the values for WMAP). Second, Higher
Criticism offers a way to locate a small portion of data that accounts for the
non-Gaussianity. Using Higher Criticism, we have successfully identified a ring
of pixels centered at (l\approx 209 deg, b\approx -57 deg), which seems to
account for the observed detection of non-Gaussianity at the wavelet scale of 5
degrees. Note that the detection is achieved in wavelet space first. Second, it
is always possible that a fraction of pixels within the ring might deviate from
Gaussianity even if they do not appear to be above the 99% confidence level in
wavelet space. The location of the ring coincides with the cold spot detected
in Vielva et al. 2004 and Cruz et al. 2005.Comment: submitted to MNRA
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