Deep Learning
Demand Forecasting for Platelet Usage: from Univariate Time Series to Multivariate Models
Motamedi, Maryam, Li, Na, Down, Douglas G., Heddle, Nancy M.
Platelet products are both expensive and have very short shelf lives. As usage rates for platelets are highly variable, the effective management of platelet demand and supply is very important yet challenging. The primary goal of this paper is to present an efficient forecasting model for platelet demand at Canadian Blood Services (CBS). To accomplish this goal, four different demand forecasting methods, ARIMA (Auto Regressive Moving Average), Prophet, lasso regression (least absolute shrinkage and selection operator) and LSTM (Long Short-Term Memory) networks are utilized and evaluated. We use a large clinical dataset for a centralized blood distribution centre for four hospitals in Hamilton, Ontario, spanning from 2010 to 2018 and consisting of daily platelet transfusions along with information such as the product specifications, the recipients' characteristics, and the recipients' laboratory test results. This study is the first to utilize different methods from statistical time series models to data-driven regression and a machine learning technique for platelet transfusion using clinical predictors and with different amounts of data. We find that the multivariate approaches have the highest accuracy in general, however, if sufficient data are available, a simpler time series approach such as ARIMA appears to be sufficient. We also comment on the approach to choose clinical indicators (inputs) for the multivariate models.
OAAE: Adversarial Autoencoders for Novelty Detection in Multi-modal Normality Case via Orthogonalized Latent Space
An, Sungkwon, Kim, Jeonghoon, Kang, Myungjoo, Razaei, Shahbaz, Liu, Xin
Novelty detection using deep generative models such as autoencoder, generative adversarial networks mostly takes image reconstruction error as novelty score function. However, image data, high dimensional as it is, contains a lot of different features other than class information which makes models hard to detect novelty data. The problem gets harder in multi-modal normality case. To address this challenge, we propose a new way of measuring novelty score in multi-modal normality cases using orthogonalized latent space. Specifically, we employ orthogonal low-rank embedding in the latent space to disentangle the features in the latent space using mutual class information. With the orthogonalized latent space, novelty score is defined by the change of each latent vector. Proposed algorithm was compared to state-of-the-art novelty detection algorithms using GAN such as RaPP and OCGAN, and experimental results show that ours outperforms those algorithms.
Infinitely Wide Tensor Networks as Gaussian Process
Gaussian Process is a non-parametric prior which can be understood as a distribution on the function space intuitively. It is known that by introducing appropriate prior to the weights of the neural networks, Gaussian Process can be obtained by taking the infinite-width limit of the Bayesian neural networks from a Bayesian perspective. In this paper, we explore the infinitely wide Tensor Networks and show the equivalence of the infinitely wide Tensor Networks and the Gaussian Process. We study the pure Tensor Network and another two extended Tensor Network structures: Neural Kernel Tensor Network and Tensor Network hidden layer Neural Network and prove that each one will converge to the Gaussian Process as the width of each model goes to infinity. (We note here that Gaussian Process can also be obtained by taking the infinite limit of at least one of the bond dimensions $\alpha_{i}$ in the product of tensor nodes, and the proofs can be done with the same ideas in the proofs of the infinite-width cases.) We calculate the mean function (mean vector) and the covariance function (covariance matrix) of the finite dimensional distribution of the induced Gaussian Process by the infinite-width tensor network with a general set-up. We study the properties of the covariance function and derive the approximation of the covariance function when the integral in the expectation operator is intractable. In the numerical experiments, we implement the Gaussian Process corresponding to the infinite limit tensor networks and plot the sample paths of these models. We study the hyperparameters and plot the sample path families in the induced Gaussian Process by varying the standard deviations of the prior distributions. As expected, the parameters in the prior distribution namely the hyper-parameters in the induced Gaussian Process controls the characteristic lengthscales of the Gaussian Process.
Do We Really Need Deep Learning Models for Time Series Forecasting?
Elsayed, Shereen, Thyssens, Daniela, Rashed, Ahmed, Schmidt-Thieme, Lars, Jomaa, Hadi Samer
Time series forecasting is a crucial task in machine learning, as it has a wide range of applications including but not limited to forecasting electricity consumption, traffic, and air quality. Traditional forecasting models relied on rolling averages, vector auto-regression and auto-regressive integrated moving averages. On the other hand, deep learning and matrix factorization models have been recently proposed to tackle the same problem with more competitive performance. However, one major drawback of such models is that they tend to be overly complex in comparison to traditional techniques. In this paper, we try to answer whether these highly complex deep learning models are without alternative. We aim to enrich the pool of simple but powerful baselines by revisiting the gradient boosting regression trees for time series forecasting. Specifically, we reconfigure the way time series data is handled by Gradient Tree Boosting models in a windowed fashion that is similar to the deep learning models. For each training window, the target values are concatenated with external features, and then flattened to form one input instance for a multi-output gradient boosting regression tree model. We conducted a comparative study on nine datasets for eight state-of-the-art deep-learning models that were presented at top-level conferences in the last years. The results demonstrated that the proposed approach outperforms all of the state-of-the-art models.
AI illustrator draws imaginative pictures to go with text captions
A neural network uses text captions to create outlandish images โ such as armchairs in the shape of avocados โ demonstrating it understands how language shapes visual culture. OpenAI, an artificial intelligence company that recently partnered with Microsoft, developed the neural network, which it calls DALL-E. It is a version of the company's GPT-3 language model that can create expansive written works based on short text prompts, but DALL-E produces images instead. "The world isn't just text," says Ilya Sutskever, co-founder of OpenAI. "Humans don't just talk: we also see. A lot of important context comes from looking."
This avocado armchair could be the future of AI
For all GPT-3's flair, its output can feel untethered from reality, as if it doesn't know what it's talking about. By grounding text in images, researchers at OpenAI and elsewhere are trying to give language models a better grasp of the everyday concepts that humans use to make sense of things. DALLยทE and CLIP come at this problem from different directions. At first glance, CLIP (Contrastive Language-Image Pre-training) is yet another image recognition system. Except that it has learned to recognize images not from labeled examples in curated data sets, as most existing models do, but from images and their captions taken from the internet.
A Decade Of AI: Most Defining Moments 2010-20
People were talking, theorising and experimenting with AI for sure, but what happened in the last decade has made AI more tangible. This was the decade when AI went mainstream. Be it access to world standard courses, platforms, libraries, frameworks, hardware -- everything just fell into place. And, it wouldn't be an exaggeration if one were to say that what was accomplished in the last ten years single-handedly fortified the foundations of our future. In this article, we look at a few of the most important breakthroughs that directly or indirectly have made AI a household name.
Rise Of Artificial Intelligence In Healthcare Sector
As we turn the corner on 2020, we find ourselves in the midst of the worst pandemic in a Century and our health care systems have been pushed to the brink of failure. To some of us it has been clear for several years that the health care system desperately needs disruption, but COVID-19 has made that easier to appreciate. Artificial intelligence is one of the biggest coming disruptions in healthcare. For some AI conjures images of a malevolent super intelligence that will outperform humanity across the board. For others AI represents a confluence of machine learning algorithms and petabytes of data that allows approximations of human decision making.
How to make artificial intelligence more democratic
This year, GPT-3, a large language model capable of understanding text, responding to questions and generating new writing examples, has drawn international media attention. The model, released by OpenAI, a California-based nonprofit that builds general-purpose artificial intelligence systems, has an impressive ability to mimic human writing, but just as notable is its massive size. To build it, researchers collected 175 billion parameters (a type of computational unit) and more than 45 terabytes of text from Common Crawl, Reddit, Wikipedia and other sources, then trained it in a process that occupied hundreds of processing units for thousands of hours. GPT-3 demonstrates a broader trend in artificial intelligence. Deep learning, which has in recent years become the dominant technique for creating new AIs, uses enormous amounts of data and computing power to fuel complex, accurate models.
AutoDropout: Learning Dropout Patterns to Regularize Deep Networks
Neural networks are often over-parameterized and hence benefit from aggressive regularization. Conventional regularization methods, such as Dropout or weight decay, do not leverage the structures of the network's inputs and hidden states. As a result, these conventional methods are less effective than methods that leverage the structures, such as SpatialDropout and DropBlock, which randomly drop the values at certain contiguous areas in the hidden states and setting them to zero. Although the locations of dropout areas random, the patterns of SpatialDropout and DropBlock are manually designed and fixed. Here we propose to learn the dropout patterns. In our method, a controller learns to generate a dropout pattern at every channel and layer of a target network, such as a ConvNet or a Transformer. The target network is then trained with the dropout pattern, and its resulting validation performance is used as a signal for the controller to learn from. We show that this method works well for both image recognition on CIFAR-10 and ImageNet, as well as language modeling on Penn Treebank and WikiText-2. The learned dropout patterns also transfers to different tasks and datasets, such as from language model on Penn Treebank to Engligh-French translation on WMT 2014. Our code will be available.