在本文中,我们通过整合具有离散的傅立叶变换(DFT)的复杂值和实值卷积神经网络(CNN)来提出一个新的EEG信号分类框架。所提出的神经网络架构由一个复杂值的卷积层,两个实值卷积层和三个完全连接的层组成。我们的方法可以有效利用DFT中包含的相信息。我们使用两个模拟的EEG信号和一个基准数据集验证我们的方法,并将其与两个广泛使用的框架进行比较。与对基准数据集进行分类的现有方法相比,我们的方法大大减少了所使用的参数的数量并提高了准确性,并显着提高了对模拟的EEG信号进行分类的性能。
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Machine learning methods have seen increased application to geospatial environmental problems, such as precipitation nowcasting, haze forecasting, and crop yield prediction. However, many of the machine learning methods applied to mosquito population and disease forecasting do not inherently take into account the underlying spatial structure of the given data. In our work, we apply a spatially aware graph neural network model consisting of GraphSAGE layers to forecast the presence of West Nile virus in Illinois, to aid mosquito surveillance and abatement efforts within the state. More generally, we show that graph neural networks applied to irregularly sampled geospatial data can exceed the performance of a range of baseline methods including logistic regression, XGBoost, and fully-connected neural networks.
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Electronic Health Records (EHRs) hold detailed longitudinal information about each patient's health status and general clinical history, a large portion of which is stored within the unstructured text. Temporal modelling of this medical history, which considers the sequence of events, can be used to forecast and simulate future events, estimate risk, suggest alternative diagnoses or forecast complications. While most prediction approaches use mainly structured data or a subset of single-domain forecasts and outcomes, we processed the entire free-text portion of EHRs for longitudinal modelling. We present Foresight, a novel GPT3-based pipeline that uses NER+L tools (i.e. MedCAT) to convert document text into structured, coded concepts, followed by providing probabilistic forecasts for future medical events such as disorders, medications, symptoms and interventions. Since large portions of EHR data are in text form, such an approach benefits from a granular and detailed view of a patient while introducing modest additional noise. On tests in two large UK hospitals (King's College Hospital, South London and Maudsley) and the US MIMIC-III dataset precision@10 of 0.80, 0.81 and 0.91 was achieved for forecasting the next biomedical concept. Foresight was also validated on 34 synthetic patient timelines by 5 clinicians and achieved relevancy of 97% for the top forecasted candidate disorder. Foresight can be easily trained and deployed locally as it only requires free-text data (as a minimum). As a generative model, it can simulate follow-on disorders, medications and interventions for as many steps as required. Foresight is a general-purpose model for biomedical concept modelling that can be used for real-world risk estimation, virtual trials and clinical research to study the progression of diseases, simulate interventions and counterfactuals, and for educational purposes.
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Because of their close relationship with humans, non-human apes (chimpanzees, bonobos, gorillas, orangutans, and gibbons, including siamangs) are of great scientific interest. The goal of understanding their complex behavior would be greatly advanced by the ability to perform video-based pose tracking. Tracking, however, requires high-quality annotated datasets of ape photographs. Here we present OpenApePose, a new public dataset of 71,868 photographs, annotated with 16 body landmarks, of six ape species in naturalistic contexts. We show that a standard deep net (HRNet-W48) trained on ape photos can reliably track out-of-sample ape photos better than networks trained on monkeys (specifically, the OpenMonkeyPose dataset) and on humans (COCO) can. This trained network can track apes almost as well as the other networks can track their respective taxa, and models trained without one of the six ape species can track the held out species better than the monkey and human models can. Ultimately, the results of our analyses highlight the importance of large specialized databases for animal tracking systems and confirm the utility of our new ape database.
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Knowledge of the symmetries of reinforcement learning (RL) systems can be used to create compressed and semantically meaningful representations of a low-level state space. We present a method of automatically detecting RL symmetries directly from raw trajectory data without requiring active control of the system. Our method generates candidate symmetries and trains a recurrent neural network (RNN) to discriminate between the original trajectories and the transformed trajectories for each candidate symmetry. The RNN discriminator's accuracy for each candidate reveals how symmetric the system is under that transformation. This information can be used to create high-level representations that are invariant to all symmetries on a dataset level and to communicate properties of the RL behavior to users. We show in experiments on two simulated RL use cases (a pusher robot and a UAV flying in wind) that our method can determine the symmetries underlying both the environment physics and the trained RL policy.
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Hidden parameters are latent variables in reinforcement learning (RL) environments that are constant over the course of a trajectory. Understanding what, if any, hidden parameters affect a particular environment can aid both the development and appropriate usage of RL systems. We present an unsupervised method to map RL trajectories into a feature space where distance represents the relative difference in system behavior due to hidden parameters. Our approach disentangles the effects of hidden parameters by leveraging a recurrent neural network (RNN) world model as used in model-based RL. First, we alter the standard world model training algorithm to isolate the hidden parameter information in the world model memory. Then, we use a metric learning approach to map the RNN memory into a space with a distance metric approximating a bisimulation metric with respect to the hidden parameters. The resulting disentangled feature space can be used to meaningfully relate trajectories to each other and analyze the hidden parameter. We demonstrate our approach on four hidden parameters across three RL environments. Finally we present two methods to help identify and understand the effects of hidden parameters on systems.
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Producing high-quality forecasts of key climate variables such as temperature and precipitation on subseasonal time scales has long been a gap in operational forecasting. Recent studies have shown promising results using machine learning (ML) models to advance subseasonal forecasting (SSF), but several open questions remain. First, several past approaches use the average of an ensemble of physics-based forecasts as an input feature of these models. However, ensemble forecasts contain information that can aid prediction beyond only the ensemble mean. Second, past methods have focused on average performance, whereas forecasts of extreme events are far more important for planning and mitigation purposes. Third, climate forecasts correspond to a spatially-varying collection of forecasts, and different methods account for spatial variability in the response differently. Trade-offs between different approaches may be mitigated with model stacking. This paper describes the application of a variety of ML methods used to predict monthly average precipitation and two meter temperature using physics-based predictions (ensemble forecasts) and observational data such as relative humidity, pressure at sea level, or geopotential height, two weeks in advance for the whole continental United States. Regression, quantile regression, and tercile classification tasks using linear models, random forests, convolutional neural networks, and stacked models are considered. The proposed models outperform common baselines such as historical averages (or quantiles) and ensemble averages (or quantiles). This paper further includes an investigation of feature importance, trade-offs between using the full ensemble or only the ensemble average, and different modes of accounting for spatial variability.
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In this era of pandemic, the future of healthcare industry has never been more exciting. Artificial intelligence and machine learning (AI & ML) present opportunities to develop solutions that cater for very specific needs within the industry. Deep learning in healthcare had become incredibly powerful for supporting clinics and in transforming patient care in general. Deep learning is increasingly being applied for the detection of clinically important features in the images beyond what can be perceived by the naked human eye. Chest X-ray images are one of the most common clinical method for diagnosing a number of diseases such as pneumonia, lung cancer and many other abnormalities like lesions and fractures. Proper diagnosis of a disease from X-ray images is often challenging task for even expert radiologists and there is a growing need for computerized support systems due to the large amount of information encoded in X-Ray images. The goal of this paper is to develop a lightweight solution to detect 14 different chest conditions from an X ray image. Given an X-ray image as input, our classifier outputs a label vector indicating which of 14 disease classes does the image fall into. Along with the image features, we are also going to use non-image features available in the data such as X-ray view type, age, gender etc. The original study conducted Stanford ML Group is our base line. Original study focuses on predicting 5 diseases. Our aim is to improve upon previous work, expand prediction to 14 diseases and provide insight for future chest radiography research.
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本文解决了利益区域(ROI)计算机断层扫描(CT)的图像重建问题。尽管基于模型的迭代方法可用于此问题,但由于乏味的参数化和缓慢的收敛性,它们的实用性通常受到限制。另外,当保留的先验不完全适合溶液空间时,可以获得不足的溶液。深度学习方法提供了一种快速的替代方法,从大型数据集中利用信息,因此可以达到高重建质量。但是,这些方法通常依赖于不考虑成像系统物理学的黑匣子,而且它们缺乏可解释性通常会感到沮丧。在两种方法的十字路口,最近都提出了展开的深度学习技术。它们将模型的物理和迭代优化算法纳入神经网络设计中,从而在各种应用中均具有出色的性能。本文介绍了一种新颖的,展开的深度学习方法,称为U-RDBFB,为ROI CT重建而设计为有限的数据。由于强大的非凸数据保真功能与稀疏性诱导正则化功能相结合,因此有效地处理了很少的截断数据。然后,嵌入在迭代重新加权方案中的块双重前向(DBFB)算法的迭代将在神经网络体系结构上展开,从而以监督的方式学习各种参数。我们的实验显示了对各种最新方法的改进,包括基于模型的迭代方案,深度学习体系结构和深度展开的方法。
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通过将从地面视图摄像头拍摄到从卫星或飞机上拍摄的架空图像的图像,通过将代理定位在搜索区域内,将代理定位在搜索区域内,将代理定位在搜索区域中。尽管地面图像和架空图像之间的观点差异使得跨视图地理定位具有挑战性,但假设地面代理可以使用全景相机,则取得了重大进展。例如,我们先前的工作(WAG)引入了搜索区域离散化,训练损失和粒子过滤器加权的变化,从而实现了城市规模的全景跨视图地理定位。但是,由于其复杂性和成本,全景相机并未在现有机器人平台中广泛使用。非Panoramic跨视图地理定位更适用于机器人技术,但也更具挑战性。本文介绍了受限的FOV广泛地理定位(Rewag),这是一种跨视图地理定位方法,通过创建姿势吸引的嵌入并提供将粒子姿势纳入暹罗网络,将其概括为与标准的非填充地面摄像机一起使用,以供与标准的非卧型地面摄像机一起使用。 Rewag是一种神经网络和粒子滤波器系统,能够在GPS下的环境中全球定位移动代理,仅具有探测仪和90度FOV摄像机,其本地化精度与使用全景相机实现并提高本地化精度相似的定位精度与基线视觉变压器(VIT)方法相比,100倍。一个视频亮点,该视频亮点在https://youtu.be/u_obqrt8qce上展示了几十公里的测试路径上的收敛。
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