157 research outputs found
Multi-Channel Target Speaker Extraction with Refinement: The WavLab Submission to the Second Clarity Enhancement Challenge
This paper describes our submission to the Second Clarity Enhancement
Challenge (CEC2), which consists of target speech enhancement for hearing-aid
(HA) devices in noisy-reverberant environments with multiple interferers such
as music and competing speakers.
Our approach builds upon the powerful iterative neural/beamforming
enhancement (iNeuBe) framework introduced in our recent work, and this paper
extends it for target speaker extraction. We therefore name the proposed
approach as iNeuBe-X, where the X stands for extraction. To address the
challenges encountered in the CEC2 setting, we introduce four major novelties:
(1) we extend the state-of-the-art TF-GridNet model, originally designed for
monaural speaker separation, for multi-channel, causal speech enhancement, and
large improvements are observed by replacing the TCNDenseNet used in iNeuBe
with this new architecture;
(2) we leverage a recent dual window size approach with future-frame
prediction to ensure that iNueBe-X satisfies the 5 ms constraint on algorithmic
latency required by CEC2;
(3) we introduce a novel speaker-conditioning branch for TF-GridNet to
achieve target speaker extraction;
(4) we propose a fine-tuning step, where we compute an additional loss with
respect to the target speaker signal compensated with the listener audiogram.
Without using external data, on the official development set our best model
reaches a hearing-aid speech perception index (HASPI) score of 0.942 and a
scale-invariant signal-to-distortion ratio improvement (SI-SDRi) of 18.8 dB.
These results are promising given the fact that the CEC2 data is extremely
challenging (e.g., on the development set the mixture SI-SDR is -12.3 dB). A
demo of our submitted system is available at WAVLab CEC2 demo
Exploring the Integration of Speech Separation and Recognition with Self-Supervised Learning Representation
Neural speech separation has made remarkable progress and its integration
with automatic speech recognition (ASR) is an important direction towards
realizing multi-speaker ASR. This work provides an insightful investigation of
speech separation in reverberant and noisy-reverberant scenarios as an ASR
front-end. In detail, we explore multi-channel separation methods, mask-based
beamforming and complex spectral mapping, as well as the best features to use
in the ASR back-end model. We employ the recent self-supervised learning
representation (SSLR) as a feature and improve the recognition performance from
the case with filterbank features. To further improve multi-speaker recognition
performance, we present a carefully designed training strategy for integrating
speech separation and recognition with SSLR. The proposed integration using
TF-GridNet-based complex spectral mapping and WavLM-based SSLR achieves a 2.5%
word error rate in reverberant WHAMR! test set, significantly outperforming an
existing mask-based MVDR beamforming and filterbank integration (28.9%).Comment: Accepted to IEEE WASPAA 202
Height Constitutes an Important Predictor of Mortality in End-Stage Renal Disease
Aim. Height is an important determinant of augmentation index (AI) that anticipates cardiovascular prognosis. There is a scanty of the data whether short height predicts survival in patients with end-stage renal diseases, a high risk population. Methods. Fifty two hypertensive patients with type 2 diabetic nephropathy receiving hemodialysis and 52 patients with nondiabetic nephropathy were enrolled. In addition to AI estimated with radial artery tonometry, classical cardiovascular risk factors were considered. Patients were followed for 2 years to assess cardiovascular prognosis. Results. Cox hazards regression revealed that both smoking and shortness in height independently contributed to total mortality and indicated that smoking as well as the presence of left ventricular hypertrophy predicted cardiovascular mortality. Our findings implicated that high AI, the presence of diabetes, and low high-density lipoprotein cholesterol were significant contributors to cardiovascular events. Conclusions. Our findings provide new evidence that shortness in height independently contributes to total mortality in hemodialysis patients
Silver Nanoparticles Induce Tight Junction Disruption and Astrocyte Neurotoxicity in a Rat Blood-Brain Barrier Primary Triple Coculture Model
BACKGROUND: Silver nanoparticles (Ag-NPs) can enter the brain and induce neurotoxicity. However, the toxicity of Ag-NPs on the blood-brain barrier (BBB) and the underlying mechanism(s) of action on the BBB and the brain are not well understood.
METHOD: To investigate Ag-NP suspension (Ag-NPS)-induced toxicity, a triple coculture BBB model of rat brain microvascular endothelial cells, pericytes, and astrocytes was established. The BBB permeability and tight junction protein expression in response to Ag-NPS, NP-released Ag ions, and polystyrene-NP exposure were investigated. Ultrastructural changes of the microvascular endothelial cells, pericytes, and astrocytes were observed using transmission electron microscopy (TEM). Global gene expression of astrocytes was measured using a DNA microarray.
RESULTS: A triple coculture BBB model of primary rat brain microvascular endothelial cells, pericytes, and astrocytes was established, with the transendothelial electrical resistance values \u3e200 Ω·cm2. After Ag-NPS exposure for 24 hours, the BBB permeability was significantly increased and expression of the tight junction (TJ) protein ZO-1 was decreased. Discontinuous TJs were also observed between microvascular endothelial cells. After Ag-NPS exposure, severe mitochondrial shrinkage, vacuolations, endoplasmic reticulum expansion, and Ag-NPs were observed in astrocytes by TEM. Global gene expression analysis showed that three genes were upregulated and 20 genes were downregulated in astrocytes treated with Ag-NPS. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis showed that the 23 genes were associated with metabolic processes, biosynthetic processes, response to stimuli, cell death, the MAPK pathway, and so on. No GO term and KEGG pathways were changed in the released-ion or polystyrene-NP groups. Ag-NPS inhibited the antioxidant defense of the astrocytes by increasing thioredoxin interacting protein, which inhibits the Trx system, and decreasing Nr4a1 and Dusp1. Meanwhile, Ag-NPS induced inflammation and apoptosis through modulation of the MAPK pathway or B-cell lymphoma-2 expression or mTOR activity in astrocytes.
CONCLUSION: These results draw our attention to the importance of Ag-NP-induced toxicity on the neurovascular unit and provide a better understanding of its toxicological mechanisms on astrocytes
Bioorganic synthesis of a recombinant HIV-1 fusion inhibitor, SC35EK, with an N-terminal pyroglutamate capping group.
The bioorganic synthesis of an end-capped anti-HIV peptide from a recombinant protein was investigated. Cyanogen bromide-mediated cleavage of two Met-Gln sites across the target anti-HIV sequence generated an HIV-1 fusion inhibitor (SC35EK) analog bearing an N-terminal pyroglutamate (pGlu) residue and a C-terminal homoserine lactone (Hsl) residue. The end-capped peptide, pGlu-SC35EK-Hsl, had similar bioactivity and biophysical properties to the parent peptide, and an improved resistance to peptidase-mediated degradation was observed compared with the non-end-capped peptide obtained using standard recombinant technology
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