10,403 research outputs found
Atomic Parity Non-Conservation, Neutron Radii, and Effective Field Theories of Nuclei
Accurately calibrated effective field theories are used to compute atomic
parity non-conserving (APNC) observables. Although accurately calibrated, these
effective field theories predict a large spread in the neutron skin of heavy
nuclei. While the neutron skin is strongly correlated to a large number of
physical observables, in this contribution we focus on its impact on new
physics through APNC observables. The addition of an isoscalar-isovector
coupling constant to the effective Lagrangian generates a wide range of values
for the neutron skin of heavy nuclei without compromising the success of the
model in reproducing well constrained nuclear observables. Earlier studies have
suggested that the use of isotopic ratios of APNC observables may eliminate
their sensitivity to atomic structure. This leaves nuclear structure
uncertainties as the main impediment for identifying physics beyond the
standard model. We establish that uncertainties in the neutron skin of heavy
nuclei are at present too large to measure isotopic ratios to better than the
0.1% accuracy required to test the standard model. However, we argue that such
uncertainties will be significantly reduced by the upcoming measurement of the
neutron radius in 208Pb at the Jefferson Laboratory.Comment: 24 pages, 6 figures, revtex4; one figure adde
Magnetic and Transport Properties in (=00.4)
Magnetic and transport properties of () system have been investigated. A broad maximum in M(T) curve,
indicative of low-dimensional antiferromagnetic ordering originated from
layers, is observed in Ca-free sample. With increasing Ca
doping level up to 0.2, the M(T) curve remains almost unchanged, while
resistivity is reduced by three orders. Higher Ca doping level leads to a
drastic change of magnetic properties. In comparison with the samples with
, the temperature corresponding to the maximum of M(T) is much
lowered for the sample =0.3. The sample =0.4 shows a small kink instead
of a broad maximum and a weak ferromagnetic feature. The electrical transport
behavior is found to be closely related to magnetic properties for the sample
=0.2, 0.25, 0.3, 0.4. It suggests that layers are involved
in charge transport in addition to conducting planes to interpret the
correlation between magnetism and charge transport. X-ray photoelectron
spectroscopy studies give an additional evidence of the the transfer of the
holes into the charge reservoir
The Microsoft 2016 Conversational Speech Recognition System
We describe Microsoft's conversational speech recognition system, in which we
combine recent developments in neural-network-based acoustic and language
modeling to advance the state of the art on the Switchboard recognition task.
Inspired by machine learning ensemble techniques, the system uses a range of
convolutional and recurrent neural networks. I-vector modeling and lattice-free
MMI training provide significant gains for all acoustic model architectures.
Language model rescoring with multiple forward and backward running RNNLMs, and
word posterior-based system combination provide a 20% boost. The best single
system uses a ResNet architecture acoustic model with RNNLM rescoring, and
achieves a word error rate of 6.9% on the NIST 2000 Switchboard task. The
combined system has an error rate of 6.2%, representing an improvement over
previously reported results on this benchmark task
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