389 research outputs found
Experimental phase-space-based optical amplification of scar modes
Waves billiard which are chaotic in the geometrical limit are known to
support non-generic spatially localized modes called scar modes. The
interaction of the scar modes with gain has been recently investigated in
optics in micro-cavity lasers and vertically-cavity surface-emitting lasers.
Exploiting the localization properties of scar modes in their wave analogous
phase space representation, we report experimental results of scar modes
selection by gain in a doped D-shaped optical fiber
RWTH ASR Systems for LibriSpeech: Hybrid vs Attention -- w/o Data Augmentation
We present state-of-the-art automatic speech recognition (ASR) systems
employing a standard hybrid DNN/HMM architecture compared to an attention-based
encoder-decoder design for the LibriSpeech task. Detailed descriptions of the
system development, including model design, pretraining schemes, training
schedules, and optimization approaches are provided for both system
architectures. Both hybrid DNN/HMM and attention-based systems employ
bi-directional LSTMs for acoustic modeling/encoding. For language modeling, we
employ both LSTM and Transformer based architectures. All our systems are built
using RWTHs open-source toolkits RASR and RETURNN. To the best knowledge of the
authors, the results obtained when training on the full LibriSpeech training
set, are the best published currently, both for the hybrid DNN/HMM and the
attention-based systems. Our single hybrid system even outperforms previous
results obtained from combining eight single systems. Our comparison shows that
on the LibriSpeech 960h task, the hybrid DNN/HMM system outperforms the
attention-based system by 15% relative on the clean and 40% relative on the
other test sets in terms of word error rate. Moreover, experiments on a reduced
100h-subset of the LibriSpeech training corpus even show a more pronounced
margin between the hybrid DNN/HMM and attention-based architectures.Comment: Proceedings of INTERSPEECH 201
Myocardial MIBG scintigraphy: a useful clinical tool?: A retrospective study in 50 parkinsonian patients
Meta-iodbenzylguanidine scintigraphy (MIBG scintigraphy) shows reduced uptake in idiopathic Parkinson's disease (IPD), idiopathic REM sleep behavior disorder (IRBD) and Lewy body dementia (LBD), but not in other parkinsonian or dementia syndromes. We retrospectively reevaluated 50 patients. Concordance rate between last clinical diagnosis and scintigraphy diagnosis was only given in two-thirds of the patients. Confounding factors were: decreasing heart/mediastinum ratio (HMR) with progressive age, higher HMR in women and possibly interference with antihypertensive medication. Standardization of the methods and precise clinical guidelines are warranted for better clinical us
Efficient Training of Neural Transducer for Speech Recognition
As one of the most popular sequence-to-sequence modeling approaches for
speech recognition, the RNN-Transducer has achieved evolving performance with
more and more sophisticated neural network models of growing size and
increasing training epochs. While strong computation resources seem to be the
prerequisite of training superior models, we try to overcome it by carefully
designing a more efficient training pipeline. In this work, we propose an
efficient 3-stage progressive training pipeline to build highly-performing
neural transducer models from scratch with very limited computation resources
in a reasonable short time period. The effectiveness of each stage is
experimentally verified on both Librispeech and Switchboard corpora. The
proposed pipeline is able to train transducer models approaching
state-of-the-art performance with a single GPU in just 2-3 weeks. Our best
conformer transducer achieves 4.1% WER on Librispeech test-other with only 35
epochs of training.Comment: accepted at Interspeech 202
Thulium environment in a silica doped optical fibre
Thulium-doped optical fibre amplifiers (TDFA) are developed to extend the
optical telecommunication wavelength division multiplexing (WDM) bandwidth in
the so-called S-band (1460-1530 nm). The radiative transition at 1.47 lm (3H4
-> 3F4) competes with a non-radiative multi-phonon de-excitation (3H4 -> 3H5).
The quantum efficiency of the transition of interest is then highly affected by
the phonon energy (Ep) of the material. For reliability reasons, oxide glasses
are preferred but suffer from high phonon energy. In the case of silica glass,
Ep is around 1100 cm-1 and quantum efficiency is as low as 2%. To improve it,
phonon energy in the thulium environment must be lowered. For that reason,
aluminium is added and we explore three different core compositions: pure
silica, and silica slightly modified with germanium or phosphorus. The role of
aluminium is studied through fluorescence decay curves, fitted according to the
continuous function decay analysis. From this analysis, modification of the
thulium local environment due to aluminium is evidenced
Erratum to: Myocardial MIBG scintigraphy: a useful clinical tool?: A retrospective study in 50 parkinsonian patients
Meta-iodbenzylguanidine scintigraphy (MIBG scintigraphy) shows reduced uptake in idiopathic Parkinson's disease (IPD), idiopathic REM sleep behavior disorder (IRBD) and Lewy body dementia (LBD), but not in other parkinsonian or dementia syndromes. We retrospectively reevaluated 50 patients. Concordance rate between last clinical diagnosis and scintigraphy diagnosis was only given in two-thirds of the patients. Confounding factors were: decreasing heart/mediastinum ratio (HMR) with progressive age, higher HMR in women and possibly interference with antihypertensive medication. Standardization of the methods and precise clinical guidelines are warranted for better clinical us
Voluntary counseling and testing for HIV among high school students in the Tiko health district, Cameroon
The objective of this study was to evaluate the use of voluntary counseling and testing (VCT) services for HIV by high school students in the Tiko health district (THD), Cameroon. A cross sectional descriptive, analytical study was conducted using a pre-established questionnaire among high school students in the Tiko health district where a multi stage sampling method was used. A total of 474 students were included in the study. Among them, 350 (73.8%) had heard about VCT, 136 (27.8%) had undergone VCT and 329 (69.4%) were willing to undergo VCT. The use of VCT services was positively associated with age (p<0.001), sex (p<0.001), school (p<0.001), sexual activity (p=0.001), attitude (p=0.001) towards and knowledge of VCT (p<0.001). Knowledge of VCT among the students was high but the use of VCT services was low. We recommend that free screening for HIV should be offered in secondary schools of THD.Pan African Medical Journal 2102; 13:1
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