DNN-Based Multi-Frame MVDR Filtering for Single-Microphone Speech Enhancement

Multi-frame approaches for single-microphone speech enhancement, e.g., the multi-frame minimum-variance-distortionless-response (MVDR) filter, are able to exploit speech correlations across neighboring time frames. In contrast to single-frame approaches such as the Wiener gain, it has been shown that multi-frame approaches achieve a substantial noise reduction with hardly any speech distortion, provided that an accurate estimate of the correlation matrices and especially the speech interframe correlation vector is available. Typical estimation procedures of the correlation matrices and the speech interframe correlation (IFC) vector require an estimate of the speech presence probability (SPP) in each time-frequency bin. In this paper, we propose to use a bi-directional long short-term memory deep neural network (DNN) to estimate a speech mask and a noise mask for each time-frequency bin, using which two different SPP estimates are derived. Aiming at achieving a robust performance, the DNN is trained for various noise types and signal-to-noise ratios. Experimental results show that the multi-frame MVDR in combination with the proposed data-driven SPP estimator yields an increased speech quality compared to a state-of-the-art model-based estimator

Revisiting Radiation Patterns in e+e−e^+e^- Collisions

We propose four simple event-shape variables for semi-inclusive $e^+e^- \to 4$-jet events. The observables and cuts are designed to be especially sensitive to subleading aspects of the event structure, and allow to test the reliability of phenomenological QCD models in greater detail. Three of them, $\theta_{14}$, $\theta^*$, and $C_2^{(1/5)}$, focus on soft emissions off three-jet topologies with a small opening angle, for which coherence effects beyond the leading QCD dipole pattern are expected to be enhanced. A complementary variable, $M_L^2/M_H^2$, measures the ratio of the hemisphere masses in 4-jet events with a compressed scale hierarchy (Durham $y_{23}\sim y_{34}$), for which subleading $1\to 3$ splitting effects are expected to be enhanced. We consider several different parton-shower models, spanning both conventional and dipole/antenna ones, all tuned to the same $e^+e^-$ reference data, and show that a measurement of the proposed observables would allow for additional significant discriminating power between the models.Comment: 27 pages, 10 figure

Geometry of curved Yang-Mills-Higgs gauge theories

This is my Ph.D. thesis defended at 31 May 2021, and it is devoted to the study of the geometry of curved Yang-Mills-Higgs gauge theory (CYMH GT), a theory introduced by Alexei Kotov and Thomas Strobl. This theory reformulates classical gauge theory, in particular, the Lie algebra (and its action) is generalized to a Lie algebroid $E$, equipped with a connection $\nabla$, and the field strength has an extra term $\zeta$. In the classical situation $E$ is an action Lie algebroid, $\nabla$ is then the canonical flat connection with respect to such an $E$, and $\zeta\equiv 0$. The shortened main results of this Ph.D.thesis are the following; see the abstract in the thesis itself for more information: 1. Reformulating curved Yang-Mills-Higgs gauge theory, also including a thorough introduction and a coordinate-free formulation. Especially the infinitesimal gauge transformation will be generalized to a derivation on vector bundle $V$-valued functionals, induced by a Lie algebroid connection. 2. We will discuss what type of connection for the definition of the infinitesimal gauge transformation should be used, and this is argued by studying the commutator of two infinitesimal gauge transformations, viewed as derivations on $V$-valued functionals. We take the connection on $W$ then in such a way that the commutator is again an infinitesimal gauge transformation. 3. Defining an equivalence of CYMH GTs given by a field redefinition. In order to preserve the physics, this equivalence is constructed in such a way that the Lagrangian of the studied theory is invariant under this field redefinition. It is then natural to study whether there are equivalence classes admitting representatives with flat $\nabla$ and/or zero $\zeta$, and we will do so especially for Lie algebra bundles, tangent bundles and their direct products as Lie algebroids.Comment: This is my Ph.D. thesis which I have defended on 31 May 2021, in total 293 pages; the thesis lists a more detailed abstract about my main results; newer versions with several corrected typos, clarified texts et

Essays on optimal stopping in discrete and continuous time

This thesis deals with optimal stopping of Markov processes in discrete and continuous time. In the first part we study discrete time random walks with infinite time horizon. Here, a main problem of interest and guiding example is the classical Chow-Robbins game, also known as the Sn/n-problem. We derive tight upper and lower bounds for the value function of the Chow- Robbins game and related problems and use these to approximate value function and continuation set of the problems. For the Chow-Robbins game we find all integer values in the continuation set for times n ≤ 489.241. Starting from there we analyze analytic properties of value function and stopping boundary. We show that the value function of the Chow-Robbins game is non-smooth on a dense subset of the continuation set. We also show that the continuation set is non-convex and find numeric evidence that the stopping boundary is not-smooth either. Similar results hold for discrete stopping problems in a fairly general setting. The second part treats continuous time stopping problems with finite time horizon, namely problems with a Brownian motion as a driving process. For these we derive a new class of Fredholm-type integral equations for the stopping set. For large problem classes of interest, we show by analytical arguments that the equation uniquely characterizes the stopping boundary of the problem. We then use the integral equations to rigorously find the limit behavior of the stopping boundary close to the terminal time. We show that the leading-order coefficient is universal for wide classes of problems. We also use the representation for numerical purposes

Developing empirical management procedures to meet management objectives for data-limited fisheries

Most of the world’s fish stocks are considered data-limited and there are insufficient data for complex stock assessment models; nevertheless, scientifically sound management advice is required. Empirical management procedures rely on empirical data and can guide management decisions. The main goals of this project were to develop and test empirical management procedures to improve data-limited fisheries management. Candidate management procedures can be evaluated using management strategy evaluation, which simulates the managed system and management in a feedback loop. Here, many generic operating models were generated covering a wide range of life histories. First, a trend-based empirical management procedure was explored. Simulations revealed that the management performance depended on the individual growth rate of the species, and the method delivered poor performance with high risk of stock depletion for faster-growing species. However, management performance could be improved by applying a genetic algorithm and optimisation towards specified management objectives such as long-term sustainable exploitation and risk limits demanded by stakeholders. An alternative empirical method (harvest rates) was found to be applicable to faster-growing species. Optimised parameterisations of the empirical methods from generic simulations were confirmed for several case study stocks with more available data. These analyses suggested that the generic methods lead to precautionary management, but management performance can be improved through case-specific optimisation. The outcomes of this project showed that the current management practices of data-limited fisheries resources applied by the International Council for the Exploration of the Sea in Europe are insufficient and do not ensure sustainable and precautionary exploitation, even though this is required through international treaties. However, the management procedures evaluated in this study show a way to overcome current management deficiencies and indicate that simple empirical management procedures are a scientifically sound alternative to expensive model-based management approaches.Open Acces

Current concept on the pathogenesis of inflammatory bowel disease-crosstalk between genetic and microbial factors: Pathogenic bacteria and altered bacterial sensing or changes in mucosal integrity take "toll"?

The pathogenesis of inflammatory bowel disease (IBD) is only partially understood. Various environmental and host (e.g. genetic-, epithelial-, immune and non-immune) factors are involved. It is a multifactorial polygenic disease with probable genetic heterogeneity. Some genes are associated with IBD itself, while others increase the risk of ulcerative colitis (UC) or Crohn's disease (CD) or are associated with disease location and/or behaviour. This review addresses recent advances in the genetics of IBD. The article discusses the current information on the crosstalk between microbial and genetic factors (e.g. NOD2/CARD15, SLC22A46A5 and DLG5). The genetic data acquired in recent years help in understanding the pathogenesis of IBD and can identify a number of potential targets for therapeutic intervention. In the future, genetics may help more accurately diagnose and predict disease course in IBD

Development of multiple myeloma in a patient with chronic hepatitis C: A case report and review of the literature

An association between chronic hepatitis C virus (HCV) infection and essential mixed cryoglobulinaemia and non-Hodgkin lymphoma (NHL) has been suggested. However, a causative role of HCV in these conditions has not been established. The authors report a case of a 50 year-old woman with chronic hepatitis C (CHC) who has been followed up since 1998 due to a high viral load, genotype 1b and moderately elevated liver function tests (LFTs). Laboratory data and liver biopsy revealed moderate activity (grade: 5/18, stage: 1/6). In April 1999, one-year interferon therapy was started. HCV-RNA became negative with normalization of LFTs. However, the patient relapsed during treatment. In September 2002, the patient was admitted for chronic back pain. A CT examination demonstrated degenerative changes. In March 2003, multiple myeloma was diagnosed (IgG-kappa, bone marrow biopsy: 50% plasma cell infiltration). MRI revealed a compression fracture of the 5(th) lumbar vertebral body and an abdominal mass in the right lower quadrant, infiltrating the canalis spinalis. Treatment with vincristine, adriamycin and dexamethasone (VAD) was started and bisphosphonate was administered regularly. In January 2004, after six cycles of VAD therapy, the multiple myeloma regressed. Thalidomide, as a second line treatment of refractory multiple myeloma (MM) was initiated, and followed by peginterferon-(alpha)2b and ribavirin against the HCV infection in June. In June 2005, LFTs returned to normal, while HCV-RNA was negative, demonstrating an end of treatment response. Although a pathogenic role of HCV infection in malignant lymphoproliferative disorders has not been established, NHL and possibly MM may develop in CHC patients, supporting a role of a complex follow-up in these patients