476 research outputs found
Subspace Hybrid MVDR Beamforming for Augmented Hearing
Signal-dependent beamformers are advantageous over signal-independent
beamformers when the acoustic scenario - be it real-world or simulated - is
straightforward in terms of the number of sound sources, the ambient sound
field and their dynamics. However, in the context of augmented reality audio
using head-worn microphone arrays, the acoustic scenarios encountered are often
far from straightforward. The design of robust, high-performance, adaptive
beamformers for such scenarios is an on-going challenge. This is due to the
violation of the typically required assumptions on the noise field caused by,
for example, rapid variations resulting from complex acoustic environments,
and/or rotations of the listener's head. This work proposes a multi-channel
speech enhancement algorithm which utilises the adaptability of
signal-dependent beamformers while still benefiting from the computational
efficiency and robust performance of signal-independent super-directive
beamformers. The algorithm has two stages. (i) The first stage is a hybrid
beamformer based on a dictionary of weights corresponding to a set of noise
field models. (ii) The second stage is a wide-band subspace post-filter to
remove any artifacts resulting from (i). The algorithm is evaluated using both
real-world recordings and simulations of a cocktail-party scenario. Noise
suppression, intelligibility and speech quality results show a significant
performance improvement by the proposed algorithm compared to the baseline
super-directive beamformer. A data-driven implementation of the noise field
dictionary is shown to provide more noise suppression, and similar speech
intelligibility and quality, compared to a parametric dictionary.Comment: 14 pages, 10 figures, submitted for IEEE/ACM Transactions on Audio,
Speech, and Language Processing on 23-Nov-202
Analysis of the tumorigenic potential of common marmoset lymphoblastoid cells expressing a constitutively activated c-myc gene.
The respective roles of Epstein-Barr virus (EBV) and c-myc in the pathogenesis of endemic Burkitt's lymphoma (BL) are unclear. In order to help resolve the question whether constitutive expression of the c-myc gene in an EBV-immortalised B cell is sufficient to induce a tumorigenic phenotype, B cells from a common marmoset (Callithrix jacchus) were immortalised with EBV, transfected with a constitutively activated c-myc gene and inoculated into the host animals. Despite the cell line transfected with c-myc displaying enhanced growth characteristics, in vitro and in vivo experiments demonstrated that this was not sufficient to induce a tumorigenic phenotype. This supports our previous findings with EBV-immortalised human B cells transfected with an activated c-myc gene (Hotchin et al., 1990)
Quantum teleportation using active feed-forward between two Canary Islands
Quantum teleportation [1] is a quintessential prerequisite of many quantum
information processing protocols [2-4]. By using quantum teleportation, one can
circumvent the no-cloning theorem [5] and faithfully transfer unknown quantum
states to a party whose location is even unknown over arbitrary distances. Ever
since the first experimental demonstrations of quantum teleportation of
independent qubits [6] and of squeezed states [7], researchers have
progressively extended the communication distance in teleportation, usually
without active feed-forward of the classical Bell-state measurement result
which is an essential ingredient in future applications such as communication
between quantum computers. Here we report the first long-distance quantum
teleportation experiment with active feed-forward in real time. The experiment
employed two optical links, quantum and classical, over 143 km free space
between the two Canary Islands of La Palma and Tenerife. To achieve this, the
experiment had to employ novel techniques such as a frequency-uncorrelated
polarization-entangled photon pair source, ultra-low-noise single-photon
detectors, and entanglement-assisted clock synchronization. The average
teleported state fidelity was well beyond the classical limit of 2/3.
Furthermore, we confirmed the quality of the quantum teleportation procedure
(without feed-forward) by complete quantum process tomography. Our experiment
confirms the maturity and applicability of the involved technologies in
real-world scenarios, and is a milestone towards future satellite-based quantum
teleportation
Modelling Realistic User Behaviour in Information Systems Simulations as Fuzzing Aspects
In this paper we contend that the engineering of information systems is hampered by a paucity of tools to tractably model, simulate and predict the impact of realistic user behaviours on the emergent properties of the wider socio-technical system, evidenced by the plethora of case studies of system failure in the literature. We address this gap by presenting a novel approach that models ideal user behaviour as workflows, and introduces irregularities in that behaviour as aspects which fuzz the model. We demonstrate the success of this approach through a case study of software development workflows, showing that the introduction of realistic user behaviour to idealised workflows better simulates outcomes reported in the empirical software engineering literature
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