Publications

Patterns of reintubation in extremely preterm infants: a longitudinal cohort study
Wissam Shalish
Lara Kanbar
Martin Keszler
Sanjay Chawla
Lajos Kovacs
Smita Rao
Bogdan A Panaitescu
Alyse Laliberte
Doina Precup
Karen Brown
Robert E Kearney
Guilherme M Sant'Anna
2018-01-30
Pediatric Research (publié)
doi.org
Combining intraoperative ultrasound brain shift correction and augmented reality visualizations: a pilot study of eight cases
Ian J. Gerard
Marta Kersten-Oertel
Simon Drouin
Jeffery A. Hall
Kevin Petrecca
Dante De Nigris
Daniel A. Di Giovanni
Tal Arbel
D. Louis Collins
2018-01-25
Journal of Medical Imaging (publié)
doi.org
A3T: Adversarially Augmented Adversarial Training
Akram Erraqabi
Aristide Baratin
Yoshua Bengio
Simon Lacoste-Julien
Recent research showed that deep neural networks are highly sensitive to so-called adversarial perturbations, which are tiny perturbations o… (voir plus)f the input data purposely designed to fool a machine learning classifier. Most classification models, including deep learning models, are highly vulnerable to adversarial attacks. In this work, we investigate a procedure to improve adversarial robustness of deep neural networks through enforcing representation invariance. The idea is to train the classifier jointly with a discriminator attached to one of its hidden layer and trained to filter the adversarial noise. We perform preliminary experiments to test the viability of the approach and to compare it to other standard adversarial training methods.
2018-01-11
ArXiv (prépublication)
arxiv.org
arxiv.org
Modular Networks for Validating Community Detection Algorithms
Justin J Fagnan
Afra Abnar
Reihaneh Rabbany
Osmar R Zaiane
How can we accurately compare different community detection algorithms? These algorithms cluster nodes in a given network, and their perform… (voir plus)ance is often validated on benchmark networks with explicit ground-truth communities. Given the lack of cluster labels in real-world networks, a model that generates realistic networks is required for accurate evaluation of these algorithm. In this paper, we present a simple, intuitive, and flexible benchmark generator to generate intrinsically modular networks for community validation. We show how the generated networks closely comply with the characteristics observed for real networks; whereas their characteristics could be directly controlled to match wide range of real world networks. We further show how common community detection algorithms rank differently when being evaluated on these benchmarks compared to current available alternatives.
2018-01-03
ArXiv (prépublication)
arxiv.org
arxiv.org
Accelerated Stochastic Power Iteration
Peng Xu
Bryan Dawei He
Christopher De Sa
Ioannis Mitliagkas
Christopher Re
Principal component analysis (PCA) is one of the most powerful tools in machine learning. The simplest method for PCA, the power iteration, … (voir plus)requires O ( 1 / Δ ) full-data passes to recover the principal component of a matrix with eigen-gap Δ. Lanczos, a significantly more complex method, achieves an accelerated rate of O ( 1 / Δ ) passes. Modern applications, however, motivate methods that only ingest a subset of available data, known as the stochastic setting. In the online stochastic setting, simple algorithms like Oja's iteration achieve the optimal sample complexity O ( σ 2 / Δ 2 ) . Unfortunately, they are fully sequential, and also require O ( σ 2 / Δ 2 ) iterations, far from the O ( 1 / Δ ) rate of Lanczos. We propose a simple variant of the power iteration with an added momentum term, that achieves both the optimal sample and iteration complexity. In the full-pass setting, standard analysis shows that momentum achieves the accelerated rate, O ( 1 / Δ ) . We demonstrate empirically that naively applying momentum to a stochastic method, does not result in acceleration. We perform a novel, tight variance analysis that reveals the "breaking-point variance" beyond which this acceleration does not occur. By combining this insight with modern variance reduction techniques, we construct stochastic PCA algorithms, for the online and offline setting, that achieve an accelerated iteration complexity O ( 1 / Δ ) . Due to the embarassingly parallel nature of our methods, this acceleration translates directly to wall-clock time if deployed in a parallel environment. Our approach is very general, and applies to many non-convex optimization problems that can now be accelerated using the same technique.
2017-12-31
AISTATS (publié)
proceedings.mlr.press
proceedings.mlr.press
Advances in Artificial Intelligence
Ebrahim Bagheri
Jackie CK Cheung
2017-12-31
Lecture Notes in Computer Science (publié)
doi.org
Analyzing Alzheimer’s Disease Progression from Sequential Magnetic Resonance Imaging Scans Using Deep 3D Convolutional Neural Networks
Sumana Basu
Konrad Wagstyl
Azar Zandifar
Louis Collins
Adriana Romero
Doina Precup
Alzheimer’s is a progressive, neurodegenerative disease, that causes irreversible damage to the brain tissue. It impairs the ability to fo… (voir plus)rm and retrieve memory, and eventually disrupts the natural flow of life, by affecting the ability to carry out even day to day activities. The disease is typically diagnosed from the symptoms (Mini Mental State Examination, [8]), such as decline in cognitive abilities, visual and/or speech impairment, loss of memory, rather than the structural changes in the brain (biomarker) that causes it. But the pathological changes in the brain start decades before the manifestation of the symptoms [7]. Magnetic Resonance Imaging (MRI) is capable of capturing the complex changes in the brain, even if it is difficult for humans to extract those features from the low contrast, multi-dimensional MRIs [1]. There is a considerable amount of work on analyzing Alzheimer’s disease. However, the vast majority intends to predict the state of the disease at the current time step.
2017-12-31
(publié)
www.semanticscholar.org
Automatic differentiation in ML: Where we are and where we should be going
Bart Van Merriënboer
Olivier Breuleux
Arnaud Bergeron
Pascal Lamblin
We review the current state of automatic differentiation (AD) for array programming in machine learning (ML), including the different approa… (voir plus)ches such as operator overloading (OO) and source transformation (ST) used for AD, graph-based intermediate representations for programs, and source languages. Based on these insights, we introduce a new graph-based intermediate representation (IR) which specifically aims to efficiently support fully-general AD for array programming. Unlike existing dataflow programming representations in ML frameworks, our IR naturally supports function calls, higher-order functions and recursion, making ML models easier to implement. The ability to represent closures allows us to perform AD using ST without a tape, making the resulting derivative (adjoint) program amenable to ahead-of-time optimization using tools from functional language compilers, and enabling higher-order derivatives. Lastly, we introduce a proof of concept compiler toolchain called Myia which uses a subset of Python as a front end.
2017-12-31
NeurIPS (publié)
arxiv.org
arxiv.org
Bayesian Model-Agnostic Meta-Learning
Taesup Kim
Jaesik Yoon
Ousmane Dia
Sungwoong Kim
Yoshua Bengio
Sungjin Ahn
Learning to infer Bayesian posterior from a few-shot dataset is an important step towards robust meta-learning due to the model uncertainty … (voir plus)inherent in the problem. In this paper, we propose a novel Bayesian model-agnostic meta-learning method. The proposed method combines scalable gradient-based meta-learning with nonparametric variational inference in a principled probabilistic framework. During fast adaptation, the method is capable of learning complex uncertainty structure beyond a point estimate or a simple Gaussian approximation. In addition, a robust Bayesian meta-update mechanism with a new meta-loss prevents overfitting during meta-update. Remaining an efficient gradient-based meta-learner, the method is also model-agnostic and simple to implement. Experiment results show the accuracy and robustness of the proposed method in various tasks: sinusoidal regression, image classification, active learning, and reinforcement learning.
2017-12-31
Advances in Neural Information Processing Systems 31 (NeurIPS 2018) (publié)
arxiv.org
arxiv.org
BigBrain: 1D convolutional neural networks for automated sementation of cortical layers
Konrad Wagstyl
Claude Lepage
Karl Zilles
Sebastian Bludau
G. Cucurul
Alan C. Evans
Paul C Fletcher
Adriana Romero
Joseph Paul Cohen
Stéphanie Larocque
Thomas Funck
Katrin Amunts
Yoshua Bengio
2017-12-31
(publié)
www.semanticscholar.org
Challenging Conventional Segmentation Evaluation Metrics Focal Pathology ( Lesion and Tumour ) Segmentation from Patient Images
Tal Arbel
2017-12-31
(publié)
www.semanticscholar.org
ChatPainter: Improving Text to Image Generation using Dialogue
Shikhar Sharma
Dendi Suhubdy
Vincent Michalski
S Ebrahimi Kahou
Yoshua Bengio
Synthesizing realistic images from text descriptions on a dataset like Microsoft Common Objects in Context (MS COCO), where each image can c… (voir plus)ontain several objects, is a challenging task. Prior work has used text captions to generate images. However, captions might not be informative enough to capture the entire image and insufficient for the model to be able to understand which objects in the images correspond to which words in the captions. We show that adding a dialogue that further describes the scene leads to significant improvement in the inception score and in the quality of generated images on the MS COCO dataset.
2017-12-31
ICLR (Workshop) (publié)
openreview.net
openreview.net