Detection and handling of overlapping speech for speaker diarization

This thesis concerns the detection of overlapping speech segments and its further application for the improvement of speaker diarization performance. We propose the use of three spatial cross-correlation-based parameters for overlap detection on distant microphone channel data. Spatial features from dierent microphone pairs are fused by means of principal component analysis or by an approach involving a multilayer perceptron. In addition, we investigate the possibility of employing long-term prosodic information. The most suitable subset of candidate prosodic features is determined by a two-step mRMR feature selection algorithm. For segments including detected overlapping speech the speaker diarization system picks a second speaker label, and such segments are also discarded from the model training. The proposed overlap labeling technique is integrated in the Viterbi-decoding part of the diarization algorithm.Peer ReviewedPostprint (published version

Albayzin 2010 Evaluation campaign: speaker diarization

In this paper we present the evaluation results for the task of speaker diarization in broadcast news domain as part of the Albayzin 2010 evaluation campaign of language and speech technologies. The evaluation data was a subset of the Catalan broadcast news database recorded from the 3/24 TV channel. Six competing systems from five different universities were submitted for the Albayzin 2010: Speaker diarization session and the lowest diarization error rate obtained was 30.4%.Postprint (published version

Blunted apoptosis of erythrocytes in mice deficient in the heterotrimeric G-protein subunit Gαi2

Putative functions of the heterotrimeric G-protein subunit Gαi2-dependent signaling include ion channel regulation, cell differentiation, proliferation and apoptosis. Erythrocytes may, similar to apoptosis of nucleated cells, undergo eryptosis, characterized by cell shrinkage and cell membrane scrambling with phosphatidylserine (PS) exposure. Eryptosis may be triggered by increased cytosolic Ca2+ activity and ceramide. In the present study, we show that Gαi2 is expressed in both murine and human erythrocytes and further examined the survival of erythrocytes drawn from Gαi2-deficient mice (Gαi2−/−) and corresponding wild-type mice (Gαi2+/+). Our data show that plasma erythropoietin levels, erythrocyte maturation markers, erythrocyte counts, hematocrit and hemoglobin concentration were similar in Gαi2−/− and Gαi2+/+ mice but the mean corpuscular volume was significantly larger in Gαi2−/− mice. Spontaneous PS exposure of circulating Gαi2−/− erythrocytes was significantly lower than that of circulating Gαi2+/+ erythrocytes. PS exposure was significantly lower in Gαi2−/− than in Gαi2+/+ erythrocytes following ex vivo exposure to hyperosmotic shock, bacterial sphingomyelinase or C6 ceramide. Erythrocyte Gαi2 deficiency further attenuated hyperosmotic shock-induced increase of cytosolic Ca2+ activity and cell shrinkage. Moreover, Gαi2−/− erythrocytes were more resistant to osmosensitive hemolysis as compared to Gαi2+/+ erythrocytes. In conclusion, Gαi2 deficiency in erythrocytes confers partial protection against suicidal cell death

Status Update and Interim Results from the Asymptomatic Carotid Surgery Trial-2 (ACST-2)

Objectives: ACST-2 is currently the largest trial ever conducted to compare carotid artery stenting (CAS) with carotid endarterectomy (CEA) in patients with severe asymptomatic carotid stenosis requiring revascularization. Methods: Patients are entered into ACST-2 when revascularization is felt to be clearly indicated, when CEA and CAS are both possible, but where there is substantial uncertainty as to which is most appropriate. Trial surgeons and interventionalists are expected to use their usual techniques and CE-approved devices. We report baseline characteristics and blinded combined interim results for 30-day mortality and major morbidity for 986 patients in the ongoing trial up to September 2012. Results: A total of 986 patients (687 men, 299 women), mean age 68.7 years (SD ± 8.1) were randomized equally to CEA or CAS. Most (96%) had ipsilateral stenosis of 70-99% (median 80%) with contralateral stenoses of 50-99% in 30% and contralateral occlusion in 8%. Patients were on appropriate medical treatment. For 691 patients undergoing intervention with at least 1-month follow-up and Rankin scoring at 6 months for any stroke, the overall serious cardiovascular event rate of periprocedural (within 30 days) disabling stroke, fatal myocardial infarction, and death at 30 days was 1.0%. Conclusions: Early ACST-2 results suggest contemporary carotid intervention for asymptomatic stenosis has a low risk of serious morbidity and mortality, on par with other recent trials. The trial continues to recruit, to monitor periprocedural events and all types of stroke, aiming to randomize up to 5,000 patients to determine any differential outcomes between interventions. Clinical trial: ISRCTN21144362. © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved

A review of survival estimates for raptors and owls

This paper reviews the literature on survival estimates for different species of raptors and owls, examines the methods used to obtain the estimates, and draws out some general patterns arising. Estimating survival usually involves the marking of birds so that they can be recognized as individuals on subsequent encounters. Annual survival can then be estimated from: (1) birds ringed at known age (usually as nestlings) and subsequently reported by members of the public (usually as found dead), the ratio of recoveries at different ages being used to calculate annual survival; (2) marked breeding adults, trapped or re-sighted in subsequent years in particular study areas, with the proportion re-trapped (or re-sighted) in each year being taken as the minimum annual survival; (3) live encounter (trapped or re-sighted) of birds marked either as nestlings or breeding adults analysed using the capture–mark–recapture (or re-sighting) methods to estimate annual survival; (4) a combination of reports of known-age dead birds and re-trapping/re-sighting of live birds; (5) use of radio- or satellite-tracking to follow the fates of individuals; and (6) the integration of these methods with other information, such as change in numbers between years, to derive estimates of survival and other demographic parameters. Studies confined to particular areas usually give estimates of ‘apparent annual survival’, because they take no account of birds that leave the area. However, radio- or satellite-tracking makes it possible to estimate true survival, including survival of prebreeders that have low natal-site fidelity (this usually requires satellite telemetry). As in other birds, the preferred method for estimating survival has changed over time, as new and more robust methods of estimation have been developed. Methods 1 and 2 were the first to be developed, but without statistical underpinning, while methods 3–6 were developed later on the basis of formal statistical models. This difference has to be borne in mind in comparing older with newer estimates for particular species. Published survival estimates were found for three species of Cathartidae, one of Pandionidae, 29 of Accipitridae, 12 of Falconidae, one of Tytonidae and nine of Strigidae, almost all from temperate Northern Hemisphere species. In most of these species more than one estimate was available, and in some separate estimates for different age or sex groups. The main patterns to emerge included: (1) a significant tendency for annual adult survival to increase with body weight, smaller species having annual survival rates mainly of 60–70%, medium-sized species having rates mainly in the range 70–90% and the largest having rates of > 90%, in the absence of obvious human-caused losses; (2) a lower survival in the first or prebreeding years of life than in subsequent years; (3) a lack of obvious or consistent differences in survival between the sexes, where these could be distinguished; and (4) in the few species for which enough data were available, a decline in annual survival rates in the later years of life

Detection and handling of overlapping speech for speaker diarization

This thesis concerns the detection of overlapping speech segments and its further application for the improvement of speaker diarization performance. We propose the use of three spatial cross-correlation-based parameters for overlap detection on distant microphone channel data. Spatial features from dierent microphone pairs are fused by means of principal component analysis or by an approach involving a multilayer perceptron. In addition, we investigate the possibility of employing long-term prosodic information. The most suitable subset of candidate prosodic features is determined by a two-step mRMR feature selection algorithm. For segments including detected overlapping speech the speaker diarization system picks a second speaker label, and such segments are also discarded from the model training. The proposed overlap labeling technique is integrated in the Viterbi-decoding part of the diarization algorithm.Peer Reviewe

The detection of overlapping speech with prosodic features for speaker diarization

Overlapping speech is responsible for a certain amount of errors produced by tandard speaker diarization systems in meeting environment. We are investigating a set of prosody-based long-term features as a potential complement to our overlap detection system relying on short-term spectral parameters. The most relevant features are selected in a two-step process. They are firstly evaluated and sorted according to mRMR criterion and then the optimal number is determined by iterative wrapper approach. We show that the addition of prosodic features decreased overlap detection error. Detected overlap segments are used in speaker diarization to recover missed speech by assigning multiple speaker labels and to increase the purity of speaker clusters.Peer ReviewedPostprint (published version

The detection of overlapping speech with prosodic features for speaker diarization

Overlapping speech is responsible for a certain amount of errors produced by tandard speaker diarization systems in meeting environment. We are investigating a set of prosody-based long-term features as a potential complement to our overlap detection system relying on short-term spectral parameters. The most relevant features are selected in a two-step process. They are firstly evaluated and sorted according to mRMR criterion and then the optimal number is determined by iterative wrapper approach. We show that the addition of prosodic features decreased overlap detection error. Detected overlap segments are used in speaker diarization to recover missed speech by assigning multiple speaker labels and to increase the purity of speaker clusters.Peer Reviewe

Detection and handling of overlapping speech for speaker diarization

This thesis concerns the detection of overlapping speech segments and its further application for the improvement of speaker diarization performance. We propose the use of three spatial cross-correlation-based parameters for overlap detection on distant microphone channel data. Spatial features from dierent microphone pairs are fused by means of principal component analysis or by an approach involving a multilayer perceptron. In addition, we investigate the possibility of employing long-term prosodic information. The most suitable subset of candidate prosodic features is determined by a two-step mRMR feature selection algorithm. For segments including detected overlapping speech the speaker diarization system picks a second speaker label, and such segments are also discarded from the model training. The proposed overlap labeling technique is integrated in the Viterbi-decoding part of the diarization algorithm.Peer Reviewe