462 research outputs found
Uncertainty Quantification in Machine Learning for Joint Speaker Diarization and Identification
This paper studies modulation spectrum features () and mel-frequency
cepstral coefficients () in joint speaker diarization and identification
(JSID). JSID is important as speaker diarization on its own to distinguish
speakers is insufficient for many applications, it is often necessary to
identify speakers as well. Machine learning models are set up using
convolutional neural networks (CNNs) on and recurrent neural networks
\unicode{x2013} long short-term memory (LSTMs) on , then concatenating
into fully connected layers.
Experiment 1 shows models on both and have better diarization
error rates (DERs) than models on either alone; a CNN on has DER
29.09\%, compared to 27.78\% for a LSTM on and 19.44\% for a model on
both. Experiment 1 also investigates aleatoric uncertainties and shows the
model on both and has mean entropy 0.927~bits (out of 4~bits) for
correct predictions compared to 1.896~bits for incorrect predictions which,
along with entropy histogram shapes, shows the model helpfully indicates where
it is uncertain.
Experiment 2 investigates epistemic uncertainties as well as aleatoric using
Monte Carlo dropout (MCD). It compares models on both and with
models trained on x-vectors (), before applying Kalman filter smoothing on
epistemic uncertainties for resegmentation and model ensembles. While the two
models on (DERs 10.23\% and 9.74\%) outperform those on and
(DER 17.85\%) after their individual Kalman filter smoothing, combining them
using a Kalman filter smoothing method improves the DER to 9.29\%. Aleatoric
uncertainties are higher for incorrect predictions.
Both Experiments show models on do not distinguish overlapping
speakers as well as anticipated. However, Experiment 2 shows model ensembles do
better with overlapping speakers than individual models do.Comment: 12 pages, 7 figure
Paraunitary oversampled filter bank design for channel coding
Oversampled filter banks (OSFBs) have been considered for channel coding, since their redundancy can be utilised to permit the detection and correction of channel errors. In this paper, we propose an OSFB-based channel coder for a correlated additive Gaussian noise channel, of which the noise covariance matrix is assumed to be known. Based on a suitable factorisation of this matrix, we develop a design for the decoder's synthesis filter bank in order to minimise the noise power in the decoded signal, subject to admitting perfect reconstruction through paraunitarity of the filter bank. We demonstrate that this approach can lead to a significant reduction of the noise interference by exploiting both the correlation of the channel and the redundancy of the filter banks. Simulation results providing some insight into these mechanisms are provided
Functionalization of different polymers with sulfonic groups as a way to coat them with a biomimetic apatite layer
Covalent coupling of sulfonic group (–SO3H)
was attempted on different polymers to evaluate efficacy of
this functional group in inducing nucleation of apatite in
body environment, and thereupon to design a simple biomimetic
process for preparing bonelike apatite-polymer
composites. Substrates of polyethylene terephthalate
(PET), polycaprolactam (Nylon 6), high molecular weight
polyethylene (HMWPE) and ethylene-vinyl alcohol copolymer
(EVOH) were subjected to sulfonation by being
soaked in sulfuric acid (H2SO4) or chlorosulfonic acid
(ClSO3H) with different concentrations. In order to incorporate
calcium ions, the sulfonated substrates were soaked
in saturated solution of calcium hydroxide (Ca(OH)2). The
treated substrates were soaked in a simulated body fluid
(SBF). Fourier transformed infrared spectroscopy, thin-film
X-ray diffraction, and scanning electron microscopy
showed that the sulfonation and subsequent Ca(OH)2
treatments allowed formation of –SO3H groups binding
Ca2+ ions on the surface of HMWPE and EVOH, but not on
PET and Nylon 6. The HMWPE and EVOH could thus
form bonelike apatite layer on their surfaces in SBF within
7 d. These results indicate that the –SO3H groups are
effective for inducing apatite nucleation, and thereby that
surface sulfonation of polymers are effective pre-treatment
method for preparing biomimetic apatite on their surfaces
Recruitment Constraints in Singapore's Fluted Giant Clam (Tridacna squamosa) Populations - A Dispersal Model Approach
10.1371/journal.pone.0058819PLoS ONE83
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Inconsistent coral bleaching risk indicators between temperature data sources
Coral reefs are facing severe threats and are at risk of accelerated decline due to climate change-induced changes in their environment. Ongoing efforts to understand the mechanisms of coral response to warming rely on multiple sources of temperature data. Yet, it remains uncertain whether the Sea Surface Temperature (SST) data used for coral reef studies are consistent among different data products, despite potential implications for conservation. A better understanding of the consistency among the different SST data applied to coral reefs may facilitate the fusion of data into a standard product. This will improve monitoring and understanding of the impact of global warming on coral reefs. Four types of SST data across North-Western and South-Western Australia are compared to assess their differences and ability to observe high thermal stress during historical coral bleaching events. The four SST data sources included those derived from Global Circulation Models, NOAA CoralTemp SST product, ESA CCI SST product, and coral core derived SST. Coral bleaching risk indicators, Degree Heating Week (DHW), and Degree Heating Month (DHM) were calculated using these sources and compared for consistency. DHW and DHM were inconsistent among data sets and did not accurately reflect high thermal stress metrics during moderate and severe bleaching events. Some reefs did not experience bleaching in spite of high DHWs and DHMs, suggesting a mismatch in data scales, or perhaps other oceanographic factors and coral adaptation. By exploring the differences and similarities among these four data sources, this study highlights the need to compare existing indicators of thermal stress from different data sets
“Moving forward with life” : acceptability of a brief alcohol reduction intervention for people receiving antiretroviral therapy in South Africa
CITATION: Myers, B. et al. 2020. “Moving Forward with Life”: Acceptability of a Brief Alcohol Reduction Intervention for People Receiving Antiretroviral Therapy in South Africa. International Journal of Environmental Research and Public Health, 17(16). doi:10.3390/ijerph17165706The original publication is available at https://www.mdpi.com/journal/ijerphBackground: In South Africa, interventions are needed to address the impact of hazardous drinking on antiretroviral therapy among people living with HIV (PLWH). Participant feedback about these interventions can identify ways to enhance their acceptability. We interviewed participants in a randomized controlled trial of a brief motivational interviewing and problem-solving therapy (MI-PST) intervention about their perceptions of this alcohol-reduction intervention. Methods: The trial was conducted in HIV treatment clinics operating from six hospitals in the Tshwane region of South Africa. We conducted qualitative in-depth interviews with a random selection of participants. Twenty-four participants were interviewed after the final intervention session and 25 at the six-month follow up. Results: Participants believed that it was acceptable to offer PLWH, an alcohol reduction intervention during HIV treatment. They described how the MI-PST intervention had helped them reduce their alcohol consumption. Intervention components providing information on the health benefits of reduced consumption and building problem-solving and coping skills were perceived as most beneficial. Despite these perceived benefits, participants suggested minor modifications to the dosage, content, and delivery of the intervention for greater acceptability and impact. Conclusions: Findings highlight the acceptability and usefulness of this MI-PST intervention for facilitating reductions in alcohol consumption among PLWH.https://www.mdpi.com/1660-4601/17/16/5706/htmPublishers versio
Customs Law
This article summarizes important developments in 2014 in customs law, including U.S. judicial decisions, trade, legislative, administrative, and executive developments, as well as Canadian and European legal developments
The behaviour of giant clams (Bivalvia: Cardiidae: Tridacninae)
Giant clams, the largest living bivalves, live in close association with coral reefs throughout the Indo-Pacific. These iconic invertebrates perform numerous important ecological roles as well as serve as flagship species—drawing attention to the ongoing destruction of coral reefs and their associated biodiversity. To date, no review of giant clams has focussed on their behaviour, yet this component of their autecology is critical to their life history and hence conservation. Almost 100 articles published between 1865 and 2014 include behavioural observations, and these have been collated and synthesised into five sections: spawning, locomotion, feeding, anti-predation, and stress responses. Even though the exact cues for spawning in the wild have yet to be elucidated, giant clams appear to display diel and lunar periodicities in reproduction, and for some species, peak breeding seasons have been established. Perhaps surprisingly, giant clams have considerable mobility, ranging from swimming and gliding as larvae to crawling in juveniles and adults. Chemotaxis and geotaxis have been established, but giant clams are not phototactic. At least one species exhibits clumping behaviour, which may enhance physical stabilisation, facilitate reproduction, or provide protection from predators. Giant clams undergo several shifts in their mode of acquiring nutrition; starting with a lecithotrophic and planktotrophic diet as larvae, switching to pedal feeding after metamorphosis followed by the transition to a dual mode of filter feeding and phototrophy once symbiosis with zooxanthellae (Symbiodinium spp.) is established. Because of their shell weight and/or byssal attachment, adult giant clams are unable to escape rapidly from threats using locomotion. Instead, they exhibit a suite of visually mediated anti-predation behaviours that include sudden contraction of the mantle, valve adduction, and squirting of water. Knowledge on the behaviour of giant clams will benefit conservation and restocking efforts and help fine-tune mariculture techniques. Understanding the repertoire of giant clam behaviours will also facilitate the prediction of threshold levels for sustainable exploitation as well as recovery rates of depleted clam populations
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