746 research outputs found
Singled Out: Genomic analysis of uncultured microbes in marine sediments
The vast majority of abundant taxa in marine sediment environments have not yielded to culture, leaving questions about their relationship to other taxa and their functional potential unanswered. However, in the absence of active cultures, careful application of various omics methods can be used to help us make useful inferences about their evolutionary history and how they have continued to survive in environments of extreme energy deprivation. For this dissertation, I have applied comparative genomics methods to members of two uncultured groups, the recently proposed Altiarchaeales order and a cosmopolitan taxon associated with the Actinobacteria phylum. Additionally, I combined transcript recruitment and metabolomic profiles to investigate metabolisms inferred from the single-cell amplified genomes extracted from members of a taxa that thrive in Baltic Sea sediment microbial communities. In Chapter II, I establish a phylogenetic relationship across distantly related members of the order Altiarchaeales and discuss environment-specific adaptations. In Chapter III, transcript recruitment and metabolite profiles support a community-wide focus on microbial persistence with active members of the uncultured Atribacteria phylum playing an important ecological role. In Chapter IV, my analysis leads to the proposal of the new class within the Actinobacteria. Osirisbacteria is a class of Actinobacteria that is specialized for life in anoxic environments. Overall, this work offers new insights into deeply-branching microbial taxa, improved understanding of recently considered branches of the evolutionary tree, and new perspective on metabolisms important for survival in low-energy marine sediment environments
The homological spectrum via definable subcategories
We develop an alternative approach to the homological spectrum through the
lens of definable subcategories. This culminates in a proof that the
homological spectrum is homeomorphic to a quotient of the Ziegler spectrum.
Along the way, we characterise injective objects in homological residue fields
in terms of the definable subcategory corresponding to a given homological
prime. We use these results to give a purity perspective on the relationship
between the homological and Balmer spectrum.Comment: 20 pages; comments welcom
Definable functors between triangulated categories with applications to tensor-triangular geometry and representation theory
We systematically develop, study, and give applications of definable functors
between compactly generated triangulated categories. Such functors preserve
pure triangles, pure injective objects, and definable subcategories, and as
such appear in a wide range of algebraic and topological settings. The first
part of the paper is predominantly theoretical. Firstly we investigate and
characterise purity preserving functors from a triangulated category into a
finitely accessible category with products, which we term coherent functors.
This yields a new property for the restricted Yoneda embedding as the universal
coherent functor.
We build upon the utility of coherent functors to provide several equivalent
conditions for an additive, not necessarily triangulated, functor between
triangulated categories to be definable: a functor is definable if and only if
it preserves filtered homology colimits and products, if and only if it
uniquely extends along the restricted Yoneda embedding to a definable functor
between the corresponding module categories.
In the second part of the paper we give four detailed applications. The first
of these investigates functoriality of the homological spectrum along definable
functors. This generalises the work of Balmer to incorporate non-triangulated
and non-geometric functors. We then turn our attention to functoriality of the
Ziegler spectrum, an object of study in pure homological algebra and
representation theory, as well as functoriality of the rank functions
introduced by Chuang and Lazarev. Our final application investigates when the
homology associated to a t-structure is coherent, and we use this to determine
the Ziegler spectrum of injective objects in the Grothendieck hearts of certain
t-structures.Comment: 48 pages, comments welcom
Real-time Detection of AI-Generated Speech for DeepFake Voice Conversion
There are growing implications surrounding generative AI in the speech domain
that enable voice cloning and real-time voice conversion from one individual to
another. This technology poses a significant ethical threat and could lead to
breaches of privacy and misrepresentation, thus there is an urgent need for
real-time detection of AI-generated speech for DeepFake Voice Conversion. To
address the above emerging issues, the DEEP-VOICE dataset is generated in this
study, comprised of real human speech from eight well-known figures and their
speech converted to one another using Retrieval-based Voice Conversion.
Presenting as a binary classification problem of whether the speech is real or
AI-generated, statistical analysis of temporal audio features through t-testing
reveals that there are significantly different distributions. Hyperparameter
optimisation is implemented for machine learning models to identify the source
of speech. Following the training of 208 individual machine learning models
over 10-fold cross validation, it is found that the Extreme Gradient Boosting
model can achieve an average classification accuracy of 99.3% and can classify
speech in real-time, at around 0.004 milliseconds given one second of speech.
All data generated for this study is released publicly for future research on
AI speech detection
Recommended from our members
On the effects of pseudorandom and quantum-random number generators in soft computing
In this work, we argue that the implications of pseudorandom and quantum-random number generators (PRNG and QRNG) inexplicably affect the performances and behaviours of various machine learning models that require a random input. These implications are yet to be explored in soft computing until this work. We use a CPU and a QPU to generate random numbers for multiple machine learning techniques. Random numbers are employed in the random initial weight distributions of dense and convolutional neural networks, in which results show a profound difference in learning patterns for the two. In 50 dense neural networks (25 PRNG/25 QRNG), QRNG increases over PRNG for accent classification at + 0.1%, and QRNG exceeded PRNG for mental state EEG classification by + 2.82%. In 50 convolutional neural networks (25 PRNG/25 QRNG), the MNIST and CIFAR-10 problems are benchmarked, and in MNIST the QRNG experiences a higher starting accuracy than the PRNG but ultimately only exceeds it by 0.02%. In CIFAR-10, the QRNG outperforms PRNG by + 0.92%. The n-random split of a Random Tree is enhanced towards and new Quantum Random Tree (QRT) model, which has differing classification abilities to its classical counterpart, 200 trees are trained and compared (100 PRNG/100 QRNG). Using the accent and EEG classification data sets, a QRT seemed inferior to a RT as it performed on average worse by − 0.12%. This pattern is also seen in the EEG classification problem, where a QRT performs worse than a RT by − 0.28%. Finally, the QRT is ensembled into a Quantum Random Forest (QRF), which also has a noticeable effect when compared to the standard Random Forest (RF). Ten to 100 ensembles of trees are benchmarked for the accent and EEG classification problems. In accent classification, the best RF (100 RT) outperforms the best QRF (100 QRF) by 0.14% accuracy. In EEG classification, the best RF (100 RT) outperforms the best QRF (100 QRT) by 0.08% but is extremely more complex, requiring twice the amount of trees in committee. All differences are observed to be situationally positive or negative and thus are likely data dependent in their observed functional behaviour
Recommended from our members
British Sign Language Recognition via Late Fusion of Computer Vision and Leap Motion with Transfer Learning to American Sign Language
In this work, we show that a late fusion approach to multimodality in sign language recognition improves the overall ability of the model in comparison to the singular approaches of image classification (88.14%) and Leap Motion data classification (72.73%). With a large synchronous dataset of 18 BSL gestures collected from multiple subjects, two deep neural networks are benchmarked and compared to derive a best topology for each. The Vision model is implemented by a Convolutional Neural Network and optimised Artificial Neural Network, and the Leap Motion model is implemented by an evolutionary search of Artificial Neural Network topology. Next, the two best networks are fused for synchronised processing, which results in a better overall result (94.44%) as complementary features are learnt in addition to the original task. The hypothesis is further supported by application of the three models to a set of completely unseen data where a multimodality approach achieves the best results relative to the single sensor method. When transfer learning with the weights trained via British Sign Language, all three models outperform standard random weight distribution when classifying American Sign Language (ASL), and the best model overall for ASL classification was the transfer learning multimodality approach, which scored 82.55% accuracy
A Deep Evolutionary Approach to Bioinspired Classifier Optimisation for Brain-Machine Interaction
This study suggests a new approach to EEG data classification by exploring the idea of using evolutionary computation to both select useful discriminative EEG features and optimise the topology of Artificial Neural Networks. An evolutionary algorithm is applied to select the most informative features from an initial set of 2550 EEG statistical features. Optimisation of a Multilayer Perceptron (MLP) is performed with an evolutionary approach before classification to estimate the best hyperparameters of the network. Deep learning and tuning with Long Short-Term Memory (LSTM) are also explored, and Adaptive Boosting of the two types of models is tested for each problem. Three experiments are provided for comparison using different classifiers: One for attention state classification, one for emotional sentiment classification, and a third experiment in which the goal is to guess the number a subject is thinking of. The obtained results show that an Adaptive Boosted LSTM can achieve an accuracy of 84.44%, 97.06%, and 9.94% on the attentional, emotional, and number datasets, respectively. An evolutionary-optimised MLP achieves results close to the Adaptive Boosted LSTM for the two first experiments and significantly higher for the number-guessing experiment with an Adaptive Boosted DEvo MLP reaching 31.35%, while being significantly quicker to train and classify. In particular, the accuracy of the nonboosted DEvo MLP was of 79.81%, 96.11%, and 27.07% in the same benchmarks. Two datasets for the experiments were gathered using a Muse EEG headband with four electrodes corresponding to TP9, AF7, AF8, and TP10 locations of the international EEG placement standard. The EEG MindBigData digits dataset was gathered from the TP9, FP1, FP2, and TP10 locations
Cross-domain MLP and CNN Transfer Learning for Biological Signal Processing: EEG and EMG
In this work, we show the success of unsupervised transfer learning between Electroencephalographic (brainwave) classification and Electromyographic (muscular wave) domains with both MLP and CNN methods. To achieve this, signals are measured from both the brain and forearm muscles and EMG data is gathered from a 4-class gesture classification experiment via the Myo Armband, and a 3-class mental state EEG dataset is acquired via the Muse EEG Headband. A hyperheuristic multi-objective evolutionary search method is used to find the best network hyperparameters. We then use this optimised topology of deep neural network to classify both EMG and EEG signals, attaining results of 84.76% and 62.37% accuracy, respectively. Next, when pre-trained weights from the EMG classification model are used for initial distribution rather than random weight initialisation for EEG classification, 93.82%(+29.95) accuracy is reached. When EEG pre-trained weights are used for initial weight distribution for EMG, 85.12% (+0.36) accuracy is achieved. When the EMG network attempts to classify EEG, it outperforms the EEG network even without any training (+30.25% to 82.39% at epoch 0), and similarly the EEG network attempting to classify EMG data outperforms the EMG network (+2.38% at epoch 0). All transfer networks achieve higher pre-training abilities, curves, and asymptotes, indicating that knowledge transfer is possible between the two signal domains. In a second experiment with CNN transfer learning, the same datasets are projected as 2D images and the same learning process is carried out. In the CNN experiment, EMG to EEG transfer learning is found to be successful but not vice-versa, although EEG to EMG transfer learning did exhibit a higher starting classification accuracy. The significance of this work is due to the successful transfer of ability between models trained on two different biological signal domains, reducing the need for building more computationally complex models in future research
- …