6,654 research outputs found
Joint Bayesian Gaussian discriminant analysis for speaker verification
State-of-the-art i-vector based speaker verification relies on variants of
Probabilistic Linear Discriminant Analysis (PLDA) for discriminant analysis. We
are mainly motivated by the recent work of the joint Bayesian (JB) method,
which is originally proposed for discriminant analysis in face verification. We
apply JB to speaker verification and make three contributions beyond the
original JB. 1) In contrast to the EM iterations with approximated statistics
in the original JB, the EM iterations with exact statistics are employed and
give better performance. 2) We propose to do simultaneous diagonalization (SD)
of the within-class and between-class covariance matrices to achieve efficient
testing, which has broader application scope than the SVD-based efficient
testing method in the original JB. 3) We scrutinize similarities and
differences between various Gaussian PLDAs and JB, complementing the previous
analysis of comparing JB only with Prince-Elder PLDA. Extensive experiments are
conducted on NIST SRE10 core condition 5, empirically validating the
superiority of JB with faster convergence rate and 9-13% EER reduction compared
with state-of-the-art PLDA.Comment: accepted by ICASSP201
Efficient use of single molecule time traces to resolve kinetic rates, models and uncertainties
Single molecule time traces reveal the time evolution of unsynchronized
kinetic systems. Especially single molecule F\"orster resonance energy transfer
(smFRET) provides access to enzymatically important timescales, combined with
molecular distance resolution and minimal interference with the sample. Yet the
kinetic analysis of smFRET time traces is complicated by experimental
shortcomings - such as photo-bleaching and noise. Here we recapitulate the
fundamental limits of single molecule fluorescence that render the classic,
dwell-time based kinetic analysis unsuitable. In contrast, our Single Molecule
Analysis of Complex Kinetic Sequences (SMACKS) considers every data point and
combines the information of many short traces in one global kinetic rate model.
We demonstrate the potential of SMACKS by resolving the small kinetic effects
caused by different ionic strengths in the chaperone protein Hsp90. These
results show an unexpected interrelation between conformational dynamics and
ATPase activity in Hsp90.Comment: 17 pages, 6 figure
Rectified Gaussian Scale Mixtures and the Sparse Non-Negative Least Squares Problem
In this paper, we develop a Bayesian evidence maximization framework to solve
the sparse non-negative least squares (S-NNLS) problem. We introduce a family
of probability densities referred to as the Rectified Gaussian Scale Mixture
(R- GSM) to model the sparsity enforcing prior distribution for the solution.
The R-GSM prior encompasses a variety of heavy-tailed densities such as the
rectified Laplacian and rectified Student- t distributions with a proper choice
of the mixing density. We utilize the hierarchical representation induced by
the R-GSM prior and develop an evidence maximization framework based on the
Expectation-Maximization (EM) algorithm. Using the EM based method, we estimate
the hyper-parameters and obtain a point estimate for the solution. We refer to
the proposed method as rectified sparse Bayesian learning (R-SBL). We provide
four R- SBL variants that offer a range of options for computational complexity
and the quality of the E-step computation. These methods include the Markov
chain Monte Carlo EM, linear minimum mean-square-error estimation, approximate
message passing and a diagonal approximation. Using numerical experiments, we
show that the proposed R-SBL method outperforms existing S-NNLS solvers in
terms of both signal and support recovery performance, and is also very robust
against the structure of the design matrix.Comment: Under Review by IEEE Transactions on Signal Processin
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