Analyzing Hidden Representations in End-to-End Automatic Speech Recognition Systems

Neural models have become ubiquitous in automatic speech recognition systems. While neural networks are typically used as acoustic models in more complex systems, recent studies have explored end-to-end speech recognition systems based on neural networks, which can be trained to directly predict text from input acoustic features. Although such systems are conceptually elegant and simpler than traditional systems, it is less obvious how to interpret the trained models. In this work, we analyze the speech representations learned by a deep end-to-end model that is based on convolutional and recurrent layers, and trained with a connectionist temporal classification (CTC) loss. We use a pre-trained model to generate frame-level features which are given to a classifier that is trained on frame classification into phones. We evaluate representations from different layers of the deep model and compare their quality for predicting phone labels. Our experiments shed light on important aspects of the end-to-end model such as layer depth, model complexity, and other design choices.Comment: NIPS 201

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Enhanced Gas Separation through Nanoconfined Ionic Liquid in Laminated MoS₂ Membrane

Two-dimensional (2D) materials-based membranes show great potential for gas separation. Herein an ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM]­[BF₄]), was confined in the 2D channels of MoS₂-laminated membranes via an infiltration process. Compared with the corresponding bulk [BMIM]­[BF₄], nanoconfined [BMIM]­[BF₄] shows an obvious incremental increase in freezing point and a shift of vibration bands. The resulting MoS₂-supported ionic liquid membrane (MoS₂ SILM) exhibits excellent CO₂ separation performance with high CO₂ permeance (47.88 GPU) and superb selectivity for CO₂/N₂ (131.42), CO₂/CH₄ (43.52), and CO₂/H₂ (14.95), which is much better than that of neat [BMIM]­[BF₄] and [BMIM]­[BF₄]-based membranes. The outstanding performance of MoS₂ SILMs is attributed to the nanoconfined [BMIM]­[BF₄], which enables fast transport of CO₂. Long-term operation also reveals the durability and stability of the prepared MoS₂ SILMs. The method of confining ILs in the 2D nanochannels of 2D materials may pave a new way for CO₂ capture and separation

Additional file 1: Table S1. of PHF21B overexpression promotes cancer stem cell-like traits in prostate cancer cells by activating the Wnt/β-catenin signaling pathway

Correlation between PHF21B expression and clinicopathological characteristics of prostate cancer patients. (DOC 38 kb

Additional file 5: Figure S1. of PHF21B overexpression promotes cancer stem cell-like traits in prostate cancer cells by activating the Wnt/β-catenin signaling pathway

SFRP1 and SFRP2 protein expression in the indicated cells. (A-B) Enzyme-linked immunosorbent assay (ELISA) analysis of protein levels of SFRP1 (A) and SFRP2 (B) in the supernatants of PHF21B-RNAi#1-C4-2B and -PC-3 cells treated with SFRP1 or SFRP2 siRNA. Error bars represent the means ± SD of 3 independent experiments. *P < 0.05. Not significant, n.s.. (TIF 103 kb

Pressure-Assisted Synthesis of HKUST‑1 Thin Film on Polymer Hollow Fiber at Room Temperature toward Gas Separation

The scalable fabrication of continuous and defect-free metal-organic framework (MOF) films on the surface of polymeric hollow fibers, departing from ceramic supported or dense composite membranes, is a huge challenge. The critical way is to reduce the growth temperature of MOFs in aqueous or ethanol solvents. In the present work, a pressure-assisted room temperature growth strategy was carried out to fabricate continuous and well-intergrown HKUST-1 films on a polymer hollow fiber by using solid copper hydroxide nanostrands as the copper source within 40 min. These HKUST-1 films/polyvinylidenefluoride (PVDF) hollow fiber composite membranes exhibit good separation performance for binary gases with selectivity 116% higher than Knudsen values via both inside-out and outside-in modes. This provides a new way to enable for scale-up preparation of HKUST-1/polymer hollow fiber membranes, due to its superior economic and ecological advantages

Additional file 5: Table S4. of Oncogenic miR-210-3p promotes prostate cancer cell EMT and bone metastasis via NF-ÎşB signaling pathway

The relationship between miR-210-3p and clinicopathological characteristics in 149 patients with prostate cancer. (PDF 58 kb

Ultrafast Molecule Separation through Layered WS₂ Nanosheet Membranes

Two-dimensional layered materials have joined in the family of size-selective separation membranes recently. Here, chemically exfoliated tungsten disulfide (WS₂) nanosheets are assembled into lamellar thin films and explored as an ultrafast separation membrane for small molecules with size of about 3 nm. Layered WS₂ membranes exhibit 5- and 2-fold enhancement in water permeance of graphene oxide membranes and MoS₂ laminar membranes with similar rejection, respectively. To further increase the water permeance, ultrathin nanostrands are used as templates to generate more fluidic channel networks in the WS₂ membrane. The water permeation behavior and separation performance in the pressure loading–unloading process reveal that the channels created by the ultrathin nanostrands are cracked under high pressure and result in a further 2-fold increase of the flux without significantly degrading the rejection for 3 nm molecules. This is supported by finite-element-based mechanical simulation. These layered WS₂ membranes demonstrate up to 2 orders of magnitude higher separation performance than that of commercial membranes with similar rejections and hold the promising potential for water purification

Two-Dimensional Titanium Carbide for Efficiently Reductive Removal of Highly Toxic Chromium(VI) from Water

Two dimensional (2-D) Ti₃C₂T_<i>x</i> nanosheets are obtained by etching bulk Ti₃C₂T_<i>x</i> powders in HF solution and delaminating ultrasonically, which exhibit excellent removal capacity for toxic Cr­(VI) from water, due to their high surface area, well dispersibility, and reductivity. The Ti₃C₂T_<i>x</i> nanosheets delaminated by 10% HF solution present more efficient Cr­(VI) removal performance with capacity of 250 mg g^–1, and the residual concentration of Cr­(VI) in treated water is less than 5 ppb, far below the concentration (0.05 ppm) of Cr­(VI) in the drinking water standard recommended by the World Health Organization. This kind of 2-D Ti₃C₂T_<i>x</i> nanosheet can not only remove Cr­(VI) rapidly and effectively in one step from aqueous solution by reducing Cr­(VI) to Cr­(III) but also adsorb the reduced Cr­(III) simultaneously. Furthermore, these reductive 2-D Ti₃C₂T_<i>x</i> nanosheets are generally explored to remove other oxidant agents, such as K₃[Fe­(CN)₆], KMnO₄, and NaAuCl₄ solutions, by converting them to low oxidation states. These significantly expand the potential applications of 2-D Ti₃C₂T_<i>x</i> nanosheets in water treatment