Block-Online Multi-Channel Speech Enhancement Using DNN-Supported Relative Transfer Function Estimates

This work addresses the problem of block-online processing for multi-channel speech enhancement. Such processing is vital in scenarios with moving speakers and/or when very short utterances are processed, e.g., in voice assistant scenarios. We consider several variants of a system that performs beamforming supported by DNN-based voice activity detection (VAD) followed by post-filtering. The speaker is targeted through estimating relative transfer functions between microphones. Each block of the input signals is processed independently in order to make the method applicable in highly dynamic environments. Owing to the short length of the processed block, the statistics required by the beamformer are estimated less precisely. The influence of this inaccuracy is studied and compared to the processing regime when recordings are treated as one block (batch processing). The experimental evaluation of the proposed method is performed on large datasets of CHiME-4 and on another dataset featuring moving target speaker. The experiments are evaluated in terms of objective and perceptual criteria (such as signal-to-interference ratio (SIR) or perceptual evaluation of speech quality (PESQ), respectively). Moreover, word error rate (WER) achieved by a baseline automatic speech recognition system is evaluated, for which the enhancement method serves as a front-end solution. The results indicate that the proposed method is robust with respect to short length of the processed block. Significant improvements in terms of the criteria and WER are observed even for the block length of 250 ms.Comment: 10 pages, 8 figures, 4 tables. Modified version of the article accepted for publication in IET Signal Processing journal. Original results unchanged, additional experiments presented, refined discussion and conclusion

Distribution and use of grasslands in the Czech Republic and biodiversity of invertebrates

In the Czech Republic the major focus of organic farming lies in permanent grasslands management. Animal production is mostly focused on non-milk pasture beef-raising on almost the whole farm area. By contrast conventional farms do not grass sufficiently, even in areas with higher elevation. This fact is influenced by subvention programmes motivating farmers to fulfil the agroenvironmental function of agriculture using grassing, however there is no support for agriculture on arable land. Permanent grasslands are predominantly used for beef grazing. Large areas are harvested too, which affects biodiverzity. Grasslands utilized for pasture are rich in biodiversity which enhance ecosystem services. The effect of grassland management on the different taxa and assamblages is discussed. This work is focused on permanent grasslands utilization and distribution and invertebrate abundance

Diverse Mandates Regarding the ESOP Diversification Requirement Following \u3cem\u3eFifth Third Bancorp v. Dudenhoeffer\u3c/em\u3e

In Dudenhoeffer, the Court focused on the Employee Stock Ownership Plan (ESOP) as a retirement benefit plan. However, this is only one function of ESOPs. Viewed in terms of both the original intent of Congress and contemporary corporate finance, the ESOPs are designed to meet several goals, including the alignment of employee and employer interests to facilitate a wider base of capital ownership including the average employee. As the Court has lost sight of these fundamental goals, it has drifted into the fallacy of interpreting ESOPs principally as employee retirement accounts. This has led the Court to apply ERISA fiduciary obligations to the ESOP fiduciaries without regard for the special statutory status of ESOPs. This creates difficulties for plan fiduciaries in seeking to fulfill the underlying purposes of the fund while at the same time complying with the heightened duties imposed upon them by ERISA. Courts have consistently maintained that they are to enforce ERISA fiduciary standards with “uncompromising rigidity” which, when coupled with the recent ruling in Dudenhoeffer, results in significant concern for ESOP settlors and plan fiduciaries who desire to continue to use these investment vehicles for any of the myriad other purposes for which they have heretofore been employed (with apparent congressional blessing)

Nitrogen front evolution in purged polymer electrolyte membrane fuel cell with dead-ended anode

In this paper, we model and experimentally verify the evolution of liquid water and nitrogen fronts along the length of the anode channel in a proton exchange membrane fuel cell operating with a dead-ended anode that is fed by dry hydrogen. The accumulation of inert nitrogen and liquid water in the anode causes a voltage drop, which is recoverable by purging the anode. Experiments were designed to clarify the effect of N-2 blanketing, water plugging of the channels, and flooding of the gas diffusion layer. The observation of each phenomenon is facilitated by simultaneous gas chromatography measurements on samples extracted from the anode channel to measure the nitrogen content and neutron imaging to measure the liquid water distribution. A model of the accumulation is presented, which describes the dynamic evolution of a N-2 blanketing front in the anode channel leading to the development of a hydrogen starved region. The prediction of the voltage drop between purge cycles during nonwater plugging channel conditions is shown. The model is capable of describing both the two-sloped behavior of the voltage decay and the time at which the steeper slope begins by capturing the effect of H-2 concentration loss and the area of the H-2 starved region along the anode channel

One – and Two-Step Resonance Energy Transfer Between Cyanine Dyes in Layered Silicates Colloidal Systems

Resonance energy transfer (RET) is of high interest for both the basic research and practical applications. It is a phenomenon of radiationless transmission of energy between donor and acceptor molecules. In this study single- and two-step (RET) was investigated between cyanine dye cations (NK1, NK2, NK3) in colloids of layered silicate, synthetic Sumecton saponite. In these systems the dye molecules played role of the energy donors (NK1) or energy acceptors (NK2, NK3) or both (NK2). The adsorption and formation of various types of dye species was studied using visible spectroscopy. The absorption spectroscopy did not detect any significant molecular aggregation of the dyes at the surface of saponite particles. The RET process was described by fluorescence spectroscopy. Both the single- and two-step RET were detected in saponite dispersion. Effects of various parameters on the efficiency of the RET process, such as dye concentrations, saponite properties the distances between co-adsorbed dye cations were found to be essential. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3530

Siderophore Pathways and Non-traditional Antibiotic Strategies in Multi-drug Resistant Acinetobacter baumannii

The rise of antibiotic resistance is driving exploration of non-canonical antibiotic approaches, including neutralization of virulence factors. Multi-drug resistant (MDR) Gram-negative pathogens, including Acinetobacter baumannii, are of particular concern because of the small number of clinically useful antibiotics available for use. Here we both expand upon the existing knowledge of two of the siderophores of A. baumannii, acinetobactin and fimsbactin, and utilize this knowledge to synthesize novel compounds for the inhibition of pathogenic A. baumannii in whole cell assays. Furthering the current knowledge of the natural siderophore systems of A. baumannii, we were able to investigate the interaction of acinetobactin with transport proteins, as well as examine the role of the fimsbactin siderophores in iron acquisition. Specifically, we report a crystal structure of siderophore binding protein BauB bound to holo-acinetobactin along with fluorscence quenching assays of acinetobactin and preacinetobactin analogs to BauB. Additionally, we isolate fimsbactin from A. baumannii and show the importance of balance between concentrations of siderophores. Further, we explore the cooperative relationship between siderophores fimsbactin A and fimsbactin F. With this fundamental knowledge in hand, we report a new method for blocking iron acquisition in MDR A. baumannii as an antivirulence strategy using rigid oxazole analogs of the known siderophore pre-acinetobactin. In addition, we report the synthesis fimsbactin mimics and confirm utilization of siderophore uptake pathways in model A. baumannii systems. Moreover, the fully functional fimsbactin mimics possess a synthetic handle for the coupling of antibiotics allowing for simple incorporation into studies aimed at Trojan horse antibiotic delivery mechanisms