冷冻电子显微镜（Cryo-EM）已成为结构生物学中基本重要性的工具，帮助我们了解生活的基本构建基础。冷冻EM的算法挑战是共同估计未知的3D姿势和来自数百万个极其嘈杂的2D图像的生物分子的3D电子散射潜力。但是，由于其高度计算和内存成本，现有的重建算法无法轻易地与迅速增长的低温EM数据集尺寸保持同步。我们介绍了Cryoai，这是一种用于均匀构象的从头算重建算法，该构型使用基于直接梯度的粒子姿势优化和来自单粒子冷冻EM数据的电子散射电位。冷冻ai结合了一个学识渊博的编码器，该编码器将每个粒子图像的姿势与基于物理的解码器进行汇总，以将每个粒子图像汇总到散射势体积的隐式表示中。该卷存储在傅立叶域中以提高计算效率，并利用现代坐标网络体系结构来提高内存效率。结合对称损耗函数，该框架可在模拟和实验数据中与最先进的冷冻EM求解器达到质量的结果，对于大型数据集而言，一个数量级的阶数级，并且具有明显低的存储器需求现有方法。

多个摄像机制造的视频录制的可用性越来越多，为姿势和运动重建方法中的减少和深度歧义提供了新的方法。然而，多视图算法强烈依赖于相机参数;特别地，相机之间的相对介绍。在不受控制的设置中，这种依赖变为一旦转移到动态捕获一次。我们介绍Flex（免费多视图重建），一个端到端的无参数多视图模型。 Flex是无意义的参数，即它不需要任何相机参数，都不是内在的也不是外在的。我们的关键思想是骨架部件和骨长之间的3D角度是不变的相机位置。因此，学习3D旋转和骨长而不是位置允许预测所有相机视图的公共值。我们的网络采用多个视频流，学习通过新型多视图融合层的融合深度特征，并重建单一一致的骨架，其具有时间上相干的关节旋转。我们展示了人类3.6M和KTH多视图足球II数据集的定量和定性结果，以及动态摄像头捕获的合成多人视频流。我们将模型与最先进的方法进行比较，这些方法没有参与参数，并在没有相机参数的情况下显示，我们在获得相机参数可用时获取可比结果的同时优于较大的余量。我们的项目页面上可以使用代码，培训的模型，视频示例和更多材料。

We present ALFRED (Action Learning From Realistic Environments and Directives), a benchmark for learning a mapping from natural language instructions and egocentric vision to sequences of actions for household tasks. ALFRED includes long, compositional tasks with nonreversible state changes to shrink the gap between research benchmarks and real-world applications. ALFRED consists of expert demonstrations in interactive visual environments for 25k natural language directives. These directives contain both high-level goals like "Rinse off a mug and place it in the coffee maker." and low-level language instructions like "Walk to the coffee maker on the right." ALFRED tasks are more complex in terms of sequence length, action space, and language than existing visionand-language task datasets. We show that a baseline model based on recent embodied vision-and-language tasks performs poorly on ALFRED, suggesting that there is significant room for developing innovative grounded visual language understanding models with this benchmark.

Bayesian optimization provides sample-efficient global optimization for a broad range of applications, including automatic machine learning, engineering, physics, and experimental design. We introduce BOTORCH, a modern programming framework for Bayesian optimization that combines Monte-Carlo (MC) acquisition functions, a novel sample average approximation optimization approach, autodifferentiation, and variance reduction techniques. BOTORCH's modular design facilitates flexible specification and optimization of probabilistic models written in PyTorch, simplifying implementation of new acquisition functions. Our approach is backed by novel theoretical convergence results and made practical by a distinctive algorithmic foundation that leverages fast predictive distributions, hardware acceleration, and deterministic optimization. We also propose a novel "one-shot" formulation of the Knowledge Gradient, enabled by a combination of our theoretical and software contributions. In experiments, we demonstrate the improved sample efficiency of BOTORCH relative to other popular libraries.34th Conference on Neural Information Processing Systems (NeurIPS 2020),

我们介绍了互动室（Thor），这是一个视觉AI研究的框架，可在http://ai2thor.allenai.org上找到。AI2-这是由几乎逼真的3D室内场景组成的，在该场景中，AI代理可以在场景中导航并与对象进行交互以执行任务。AI2-这可以在许多不同的领域进行研究，包括但不限于深入强化学习，模仿学习，通过互动，计划，视觉问答答案，无监督的表示学习，对象检测和细分以及认知模型。AI2的目的是促进构建视觉上智能模型，并将研究推向该领域。

The performance of inertial navigation systems is largely dependent on the stable flow of external measurements and information to guarantee continuous filter updates and bind the inertial solution drift. Platforms in different operational environments may be prevented at some point from receiving external measurements, thus exposing their navigation solution to drift. Over the years, a wide variety of works have been proposed to overcome this shortcoming, by exploiting knowledge of the system current conditions and turning it into an applicable source of information to update the navigation filter. This paper aims to provide an extensive survey of information aided navigation, broadly classified into direct, indirect, and model aiding. Each approach is described by the notable works that implemented its concept, use cases, relevant state updates, and their corresponding measurement models. By matching the appropriate constraint to a given scenario, one will be able to improve the navigation solution accuracy, compensate for the lost information, and uncover certain internal states, that would otherwise remain unobservable.

We consider infinite horizon Markov decision processes (MDPs) with fast-slow structure, meaning that certain parts of the state space move "fast" (and in a sense, are more influential) while other parts transition more "slowly." Such structure is common in real-world problems where sequential decisions need to be made at high frequencies, yet information that varies at a slower timescale also influences the optimal policy. Examples include: (1) service allocation for a multi-class queue with (slowly varying) stochastic costs, (2) a restless multi-armed bandit with an environmental state, and (3) energy demand response, where both day-ahead and real-time prices play a role in the firm's revenue. Models that fully capture these problems often result in MDPs with large state spaces and large effective time horizons (due to frequent decisions), rendering them computationally intractable. We propose an approximate dynamic programming algorithmic framework based on the idea of "freezing" the slow states, solving a set of simpler finite-horizon MDPs (the lower-level MDPs), and applying value iteration (VI) to an auxiliary MDP that transitions on a slower timescale (the upper-level MDP). We also extend the technique to a function approximation setting, where a feature-based linear architecture is used. On the theoretical side, we analyze the regret incurred by each variant of our frozen-state approach. Finally, we give empirical evidence that the frozen-state approach generates effective policies using just a fraction of the computational cost, while illustrating that simply omitting slow states from the decision modeling is often not a viable heuristic.

In the present work we propose an unsupervised ensemble method consisting of oblique trees that can address the task of auto-encoding, namely Oblique Forest AutoEncoders (briefly OF-AE). Our method is a natural extension of the eForest encoder introduced in [1]. More precisely, by employing oblique splits consisting in multivariate linear combination of features instead of the axis-parallel ones, we will devise an auto-encoder method through the computation of a sparse solution of a set of linear inequalities consisting of feature values constraints. The code for reproducing our results is available at https://github.com/CDAlecsa/Oblique-Forest-AutoEncoders.

When robots learn reward functions using high capacity models that take raw state directly as input, they need to both learn a representation for what matters in the task -- the task ``features" -- as well as how to combine these features into a single objective. If they try to do both at once from input designed to teach the full reward function, it is easy to end up with a representation that contains spurious correlations in the data, which fails to generalize to new settings. Instead, our ultimate goal is to enable robots to identify and isolate the causal features that people actually care about and use when they represent states and behavior. Our idea is that we can tune into this representation by asking users what behaviors they consider similar: behaviors will be similar if the features that matter are similar, even if low-level behavior is different; conversely, behaviors will be different if even one of the features that matter differs. This, in turn, is what enables the robot to disambiguate between what needs to go into the representation versus what is spurious, as well as what aspects of behavior can be compressed together versus not. The notion of learning representations based on similarity has a nice parallel in contrastive learning, a self-supervised representation learning technique that maps visually similar data points to similar embeddings, where similarity is defined by a designer through data augmentation heuristics. By contrast, in order to learn the representations that people use, so we can learn their preferences and objectives, we use their definition of similarity. In simulation as well as in a user study, we show that learning through such similarity queries leads to representations that, while far from perfect, are indeed more generalizable than self-supervised and task-input alternatives.

While the capabilities of autonomous systems have been steadily improving in recent years, these systems still struggle to rapidly explore previously unknown environments without the aid of GPS-assisted navigation. The DARPA Subterranean (SubT) Challenge aimed to fast track the development of autonomous exploration systems by evaluating their performance in real-world underground search-and-rescue scenarios. Subterranean environments present a plethora of challenges for robotic systems, such as limited communications, complex topology, visually-degraded sensing, and harsh terrain. The presented solution enables long-term autonomy with minimal human supervision by combining a powerful and independent single-agent autonomy stack, with higher level mission management operating over a flexible mesh network. The autonomy suite deployed on quadruped and wheeled robots was fully independent, freeing the human supervision to loosely supervise the mission and make high-impact strategic decisions. We also discuss lessons learned from fielding our system at the SubT Final Event, relating to vehicle versatility, system adaptability, and re-configurable communications.