982 research outputs found
Modeling Dependent Structure for Utterances in ASR Evaluation
The bootstrap resampling method has been popular for performing significance
analysis on word error rate (WER) in automatic speech recognition (ASR)
evaluation. To deal with dependent speech data, the blockwise bootstrap
approach is also introduced. By dividing utterances into uncorrelated blocks,
this approach resamples these blocks instead of original data. However, it is
typically nontrivial to uncover the dependent structure among utterances and
identify the blocks, which might lead to subjective conclusions in statistical
testing. In this paper, we present graphical lasso based methods to explicitly
model such dependency and estimate uncorrelated blocks of utterances in a
rigorous way, after which blockwise bootstrap is applied on top of the inferred
blocks. We show the resulting variance estimator of WER in ASR evaluation is
statistically consistent under mild conditions. We also demonstrate the
validity of proposed approach on LibriSpeech dataset
Complex electronic states in double layered ruthenates (Sr1-xCax)3Ru2O7
The magnetic ground state of (SrCa)RuO (0 1) is complex, ranging from an itinerant metamagnetic state (0
0.08), to an unusual heavy-mass, nearly ferromagnetic (FM) state (0.08
0.4), and finally to an antiferromagnetic (AFM) state (0.4 1). In
this report we elucidate the electronic properties for these magnetic states,
and show that the electronic and magnetic properties are strongly coupled in
this system. The electronic ground state evolves from an AFM
quasi-two-dimensional metal for 1.0, to an Anderson localized state for
(the AFM region). When the magnetic state undergoes a
transition from the AFM to the nearly FM state, the electronic ground state
switches to a weakly localized state induced by magnetic scattering for , and then to a magnetic metallic state with the in-plane
resistivity ( 2) for .
The system eventually transforms into a Fermi liquid ground state when the
magnetic ground state enters the itinerant metamagnetic state for .
When approaches the critical composition ( 0.08), the Fermi liquid
temperature is suppressed to zero Kelvin, and non-Fermi liquid behavior is
observed. These results demonstrate the strong interplay between charge and
spin degrees of freedom in the double layered ruthenates.Comment: 10 figures. To be published in Phys. Rev.
On Galilean conformal bootstrap
In this work, we develop conformal bootstrap for Galilean conformal field
theory (GCFT). In a GCFT, the Hilbert space could be decomposed into
quasiprimary states and its global descendants. Different from the usual
conformal field theory, the quasi-primary states in a GCFT constitute
multiplets, which are block-diagonized under the Galilean boost operator. More
importantly the multiplets include the states of negative norms, indicating the
theory is not unitary. We compute global blocks of the multiplets, and discuss
the expansion of four-point functions in terms of the global blocks of the
multiplets. Furthermore we do the harmonic analysis for the Galilean conformal
symmetry and obtain an inversion formula. As the first step to apply the
Galilean conformal bootstrap, we construct generalized Galilean free theory
(GGFT) explicitly. We read the data of GGFT by using Taylor series expansion of
four-point function and the inversion formula independently, and find exact
agreement. We discuss some novel features in the Galilean conformal bootstrap,
due to the non-semisimpleness of the Galilean conformal algebra and the
non-unitarity of the GCFTs.Comment: 75 pages, 2 figures, 4 tables; v2: references added, typos corrected;
v3: references added, typos corrected, new appendices adde
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