Recurrent DNNs and its Ensembles on the TIMIT Phone Recognition Task

In this paper, we have investigated recurrent deep neural networks (DNNs) in combination with regularization techniques as dropout, zoneout, and regularization post-layer. As a benchmark, we chose the TIMIT phone recognition task due to its popularity and broad availability in the community. It also simulates a low-resource scenario that is helpful in minor languages. Also, we prefer the phone recognition task because it is much more sensitive to an acoustic model quality than a large vocabulary continuous speech recognition task. In recent years, recurrent DNNs pushed the error rates in automatic speech recognition down. But, there was no clear winner in proposed architectures. The dropout was used as the regularization technique in most cases, but combination with other regularization techniques together with model ensembles was omitted. However, just an ensemble of recurrent DNNs performed best and achieved an average phone error rate from 10 experiments 14.84 % (minimum 14.69 %) on core test set that is slightly lower then the best-published PER to date, according to our knowledge. Finally, in contrast of the most papers, we published the open-source scripts to easily replicate the results and to help continue the development.Comment: Submitted to SPECOM 2018, 20th International Conference on Speech and Compute

Transformer-based Automatic Speech Recognition of Formal and Colloquial Czech in MALACH Project

Czech is a very specific language due to its large differences between the formal and the colloquial form of speech. While the formal (written) form is used mainly in official documents, literature, and public speeches, the colloquial (spoken) form is used widely among people in casual speeches. This gap introduces serious problems for ASR systems, especially when training or evaluating ASR models on datasets containing a lot of colloquial speech, such as the MALACH project. In this paper, we are addressing this problem in the light of a new paradigm in end-to-end ASR systems -- recently introduced self-supervised audio Transformers. Specifically, we are investigating the influence of colloquial speech on the performance of Wav2Vec 2.0 models and their ability to transcribe colloquial speech directly into formal transcripts. We are presenting results with both formal and colloquial forms in the training transcripts, language models, and evaluation transcripts.Comment: to be published in Proceedings of TSD 202

Dennis Levine, an exception or the Norm: Inside Trading and Foreign Bank Secrecy

As national securities markets rapidly become international markets, the idealized precept that federal securities laws are to create a system providing equal access to information for all investors, appears to falter. One cause of this breakdown is insider trading. Traditionally prosecuted under the Securities Exchange Act of 1934,• illegal activities conducted through secret bank accounts outside U.S. borders and jurisdiction have posed a sobering challenge to prosecution of the inside trader

Synthesis and Characterization of Coloumnar Mesophases of Novel Substituted Dibenzanthracenes and Their Donor-Acceptor Mixtures

In this thesis, the synthesis and liquid crystalline properties of a series of novel dibenz[a,c]anthracenes are reported. Specifically, two dibenzanthracenecarboxylate derivatives were prepared and were found not to exhibit a mesophase. In contrast, a series of novel N-substituted dibenzanthracenedicarboximides was also synthesized and found to exhibit broad columnar temperature ranges. Several dibenzanthracenedicarboximides substituted with different alkyl chains on the nitrogen atom were prepared and their mesomorphic temperature ranges were characterized. In general, it was found that having a longer, more flexible alkyl chain on the nitrogen atom resulted in a broadening of the columnar temperature range via a lowering of the melting point transition temperature. We also prepared a novel electron donor-acceptor liquid crystal by doping a non-mesomorphic hexaalkoxydibenzanthracene with electron-poor trinitrofluorenone. In contrast to the preferred 1:1 molar ratio of donor to acceptor usually demonstrated by charge-transfer liquid crystals, this series was found to prefer a 2:1 molar ratio of donor to acceptor. Several other electron donor-acceptor series using structurally related dibenzanthracene and dibenzophenazine derivatives were found to exhibit similar behaviour suggesting that, instead of an alternating donor-acceptor stacking arrangement, more of a sandwich-like 2:1 stacking arrangement may be preferred

Determining the Structures and Properties of Biologically-relevant Ions

Gas phase studies of biologically relevant ions are increasing in popularity due to the possibility of high throughput analysis requiring minimum sample concentrations. This thesis explores the potential of differential mobility spectrometry-mass spectrometry (DMS-MS) in combination with quantum chemical calculation methods to probe the structures, energetics, and dynamics of three distinct classes of biomolecules. The first project outlines the use of DMS-MS to separate and identify protonated forms of methylated and unmethylated nucleobases to gain a fundamental understanding of their gas phase properties in relation to their role in nucleic acids. Next, DMS-MS and calculations were conducted for a large RNA system, the Varkud Satellite ribozyme active site loop VI, to study differences between its active and inactive conformations, especially through the use of negative mode hydrogen-deuterium exchange. Finally, DMS-MS was used to identify transformation products of trimethoprim, an antibiotic often found in environmental wastewaters in a reliable and efficient method. Ultimately, DMS-MS and quantum calculations have been shown to be a powerful analytical tool to investigate structures and properties of biomolecules. The methodologies described herein can have an impact in a wide variety of industries, from drug discovery to environmental wastewater cleanup

The Effect of Oxidation, Thionation, and Dimerization on the Self-Assembly and Photophysical Properties of Novel Discotic Materials

This thesis aims to increase understanding of the relationship between molecular structure and liquid crystalline temperature range by exploring the effects of oxidation, thionation, and dimerization on the self-assembly and properties of novel discotic materials. First, two alkoxy-substituted dibenzanthracenequinones were prepared by oxidation of the corresponding dibenzanthracenes. The quinone induced a liquid crystalline phase in the hexaalkoxy dibenzanthracene derivative, but not in the tetralkoxy derivative. However, both of the resulting materials were un-reactive to any further synthetic modifications that could be used to improve their properties. In comparison, two heteroaromatic dithienoanthracenedicarboximides were successfully prepared, although the addition of the thiophene was not able to induce a columnar phase in these materials. In contrast, the effect of thionation on self-assembly was explored via a series of thionated dibenzanthracenes and a series of thionated triphenylenes, both of which displayed broad columnar phases and increased aggregation in solution. In general, it was found that thionation allowed for tuning of the LUMO energy level without having a significant effect on the liquid crystalline temperature range of the material. These results, combined with the relative ease of the synthetic transformation, suggest that thionation may be a promising method for the design of novel electron-deficient liquid crystalline materials. Finally, although the target discotic dimers could not be achieved, we were able to successfully synthesize the corresponding N-substituted alkylamine dibenzanthracenes and characterize their liquid crystalline behaviour. It was found that, when compared to the corresponding alkyl-substituted derivative, the exposed amine destabilized the liquid crystalline phase. The terminal amine was successfully converted to an acetyl group; although this was observed to lead to a stabilization of the crystalline phase and a narrowing of the liquid crystalline temperature range. Overall, by characterizing both the self-assembly and photophysical properties of these materials, this thesis hopes to contribute to a better understanding of the intermolecular interactions occurring in this class of compounds and may, ultimately, help to develop materials that have future applications in organic electronics

Metformin and the risk of renal cell carcinoma: a case-control analysis

Metformin use has been associated previously with a decreased risk of cancer, but its association with renal cell carcinoma has not yet been investigated in observational studies. We aimed to explore the association between the use of metformin and other antidiabetic drugs and the risk of renal cell carcinoma (RCC). We carried out a case-control analysis in the UK-based Clinical Practice Research Datalink. We included individuals with an incident RCC between January 1995 and December 2013 younger than the age of 90 years. Six controls per case were matched on age, sex, calendar time, general practice, and number of years of active history in the Clinical Practice Research Datalink before the index date. We included BMI, smoking, alcohol consumption, hypertension, and diabetes mellitus as potential confounders in a multivariate model using conditional logistic regression to calculate odds ratios with 95% confidence intervals, and we carried out a sensitivity analysis restricted only to diabetic cases and controls. Long-term use of metformin was not associated with an altered relative risk of RCC (≥30 prescriptions, adjusted odds ratio 1.18, 95% confidence interval 0.88-1.58), nor was use of other antidiabetic drugs. Results in the sensitivity analysis including only diabetic cases and controls were largely the same. Use of metformin or other antidiabetic drugs was not associated with a materially altered risk of RCC. Further studies are warranted