Methods based on ordinary differential equations (ODEs) are widely used to build generative models of time-series. In addition to high computational overhead due to explicitly computing hidden states recurrence, existing ODE-based models fall short in learning sequence data with sharp transitions - common in many real-world systems - due to numerical challenges during optimization. In this work, we propose LS4, a generative model for sequences with latent variables evolving according to a state space ODE to increase modeling capacity. Inspired by recent deep state space models (S4), we achieve speedups by leveraging a convolutional representation of LS4 which bypasses the explicit evaluation of hidden states. We show that LS4 significantly outperforms previous continuous-time generative models in terms of marginal distribution, classification, and prediction scores on real-world datasets in the Monash Forecasting Repository, and is capable of modeling highly stochastic data with sharp temporal transitions. LS4 sets state-of-the-art for continuous-time latent generative models, with significant improvement of mean squared error and tighter variational lower bounds on irregularly-sampled datasets, while also being x100 faster than other baselines on long sequences.

The number of international benchmarking competitions is steadily increasing in various fields of machine learning (ML) research and practice. So far, however, little is known about the common practice as well as bottlenecks faced by the community in tackling the research questions posed. To shed light on the status quo of algorithm development in the specific field of biomedical imaging analysis, we designed an international survey that was issued to all participants of challenges conducted in conjunction with the IEEE ISBI 2021 and MICCAI 2021 conferences (80 competitions in total). The survey covered participants' expertise and working environments, their chosen strategies, as well as algorithm characteristics. A median of 72% challenge participants took part in the survey. According to our results, knowledge exchange was the primary incentive (70%) for participation, while the reception of prize money played only a minor role (16%). While a median of 80 working hours was spent on method development, a large portion of participants stated that they did not have enough time for method development (32%). 25% perceived the infrastructure to be a bottleneck. Overall, 94% of all solutions were deep learning-based. Of these, 84% were based on standard architectures. 43% of the respondents reported that the data samples (e.g., images) were too large to be processed at once. This was most commonly addressed by patch-based training (69%), downsampling (37%), and solving 3D analysis tasks as a series of 2D tasks. K-fold cross-validation on the training set was performed by only 37% of the participants and only 50% of the participants performed ensembling based on multiple identical models (61%) or heterogeneous models (39%). 48% of the respondents applied postprocessing steps.

Reinforcement-learning agents seek to maximize a reward signal through environmental interactions. As humans, our contribution to the learning process is through designing the reward function. Like programmers, we have a behavior in mind and have to translate it into a formal specification, namely rewards. In this work, we consider the reward-design problem in tasks formulated as reaching desirable states and avoiding undesirable states. To start, we propose a strict partial ordering of the policy space. We prefer policies that reach the good states faster and with higher probability while avoiding the bad states longer. Next, we propose an environment-independent tiered reward structure and show it is guaranteed to induce policies that are Pareto-optimal according to our preference relation. Finally, we empirically evaluate tiered reward functions on several environments and show they induce desired behavior and lead to fast learning.

We develop a wall model for large-eddy simulation (LES) that takes into account various pressure-gradient effects using multi-agent reinforcement learning (MARL). The model is trained using low-Reynolds-number flow over periodic hills with agents distributed on the wall along the computational grid points. The model utilizes a wall eddy-viscosity formulation as the boundary condition, which is shown to provide better predictions of the mean velocity field, rather than the typical wall-shear stress formulation. Each agent receives states based on local instantaneous flow quantities at an off-wall location, computes a reward based on the estimated wall-shear stress, and provides an action to update the wall eddy viscosity at each time step. The trained wall model is validated in wall-modeled LES (WMLES) of flow over periodic hills at higher Reynolds numbers, and the results show the effectiveness of the model on flow with pressure gradients. The analysis of the trained model indicates that the model is capable of distinguishing between the various pressure gradient regimes present in the flow.

Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License.

Artificial Intelligence (AI) is having a tremendous impact across most areas of science. Applications of AI in healthcare have the potential to improve our ability to detect, diagnose, prognose, and intervene on human disease. For AI models to be used clinically, they need to be made safe, reproducible and robust, and the underlying software framework must be aware of the particularities (e.g. geometry, physiology, physics) of medical data being processed. This work introduces MONAI, a freely available, community-supported, and consortium-led PyTorch-based framework for deep learning in healthcare. MONAI extends PyTorch to support medical data, with a particular focus on imaging, and provide purpose-specific AI model architectures, transformations and utilities that streamline the development and deployment of medical AI models. MONAI follows best practices for software-development, providing an easy-to-use, robust, well-documented, and well-tested software framework. MONAI preserves the simple, additive, and compositional approach of its underlying PyTorch libraries. MONAI is being used by and receiving contributions from research, clinical and industrial teams from around the world, who are pursuing applications spanning nearly every aspect of healthcare.

在本文中，我们提出了一条基于截短的签名距离函数（TSDF）体积的接触点检测的新型抓紧管道，以实现闭环7度自由度（7-DOF）在杂物环境上抓住。我们方法的关键方面是1）提议的管道以多视图融合，接触点采样和评估以及碰撞检查，可提供可靠且无碰撞的7-DOF抓手姿势，并带有真实的碰撞 - 时间性能；2）基于接触的姿势表示有效地消除了基于正常方法的歧义，从而提供了更精确和灵活的解决方案。广泛的模拟和实体机器人实验表明，在模拟和物理场景中，就掌握成功率而言，提出的管道可以选择更多的反物和稳定的抓握姿势，并优于基于正常的基线。

我们研究了一种建设性算法，该算法通过有限差异来近似于统计功能的GATEAUX衍生物，重点是因果推理功能。我们考虑了不知道先验性的概率分布，但还需要从数据估算的情况。这些估计的分布导致了经验性Gateaux衍生物，我们研究了经验，数值和分析性GATEAUX衍生物之间的关系。从反事实平均估计的案例研究开始，我们实例化有限差异与分析性GATEAUX衍生物之间的确切关系。然后，我们得出了对扰动和平滑度数值近似速率的要求，以保留一步调整的统计益处，例如速率双重运动。然后，我们研究了更复杂的功能，例如动态治疗方案和无限马尔可夫决策过程中的策略优化的线性编程公式。在存在任意约束的情况下，新发现的近似偏差调整的能力说明了构建方法对Gateaux衍生物的有用性。我们还发现，功能性（速率双重鲁棒性）的统计结构可以允许较少的有限差近似速率保守速率。但是，此属性可以特定于特定功能，例如它是针对事实的平均值，但不是无限 - 摩恩MDP策略价值。

联合学习是一种来自分散数据集的培训模型的新兴技术。在许多应用程序中，参与联合学习系统的数据所有者不仅拥有数据，还拥有一组域知识。这些知识包括人类的知识和工艺，对联邦学习任务非常有帮助。在这项工作中，我们提出了一个联合学习框架，该框架允许注入参与者的领域知识，其中关键思想是通过本地知识来完善全球模型。我们认为的方案是由真正的行业级应用激励的，我们证明了我们采用该应用的有效性。

我们考虑在具有非线性函数近似的两名玩家零和马尔可夫游戏中学习NASH平衡，其中动作值函数通过繁殖内核Hilbert Space（RKHS）中的函数近似。关键挑战是如何在高维函数空间中进行探索。我们提出了一种新颖的在线学习算法，以最大程度地减少双重性差距来找到NASH平衡。我们算法的核心是基于不确定性的乐观原理得出的上和下置信度界限。我们证明，在非常温和的假设上，我们的算法能够获得$ O（\ sqrt {t}）$遗憾，并在对奖励功能和马尔可夫游戏的基本动态下进行多项式计算复杂性。我们还提出了我们的算法的几个扩展，包括具有伯恩斯坦型奖励的算法，可以实现更严格的遗憾，以及用于模型错误指定的另一种算法，可以应用于神经功能近似。