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.

We consider an offline reinforcement learning (RL) setting where the agent need to learn from a dataset collected by rolling out multiple behavior policies. There are two challenges for this setting: 1) The optimal trade-off between optimizing the RL signal and the behavior cloning (BC) signal changes on different states due to the variation of the action coverage induced by different behavior policies. Previous methods fail to handle this by only controlling the global trade-off. 2) For a given state, the action distribution generated by different behavior policies may have multiple modes. The BC regularizers in many previous methods are mean-seeking, resulting in policies that select out-of-distribution (OOD) actions in the middle of the modes. In this paper, we address both challenges by using adaptively weighted reverse Kullback-Leibler (KL) divergence as the BC regularizer based on the TD3 algorithm. Our method not only trades off the RL and BC signals with per-state weights (i.e., strong BC regularization on the states with narrow action coverage, and vice versa) but also avoids selecting OOD actions thanks to the mode-seeking property of reverse KL. Empirically, our algorithm can outperform existing offline RL algorithms in the MuJoCo locomotion tasks with the standard D4RL datasets as well as the mixed datasets that combine the standard datasets.

Facial attractiveness prediction (FAP) aims to assess the facial attractiveness automatically based on human aesthetic perception. Previous methods using deep convolutional neural networks have boosted the performance, but their giant models lead to a deficiency in flexibility. Besides, most of them fail to take full advantage of the dataset. In this paper, we present a novel end-to-end FAP approach integrating dual label distribution and lightweight design. To make the best use of the dataset, the manual ratings, attractiveness score, and standard deviation are aggregated explicitly to construct a dual label distribution, including the attractiveness distribution and the rating distribution. Such distributions, as well as the attractiveness score, are optimized under a joint learning framework based on the label distribution learning (LDL) paradigm. As for the lightweight design, the data processing is simplified to minimum, and MobileNetV2 is selected as our backbone. Extensive experiments are conducted on two benchmark datasets, where our approach achieves promising results and succeeds in striking a balance between performance and efficiency. Ablation studies demonstrate that our delicately designed learning modules are indispensable and correlated. Additionally, the visualization indicates that our approach is capable of perceiving facial attractiveness and capturing attractive facial regions to facilitate semantic predictions.

卷积神经网络（CNN）已经实现了医学图像细分的最先进性能，但需要大量的手动注释进行培训。半监督学习（SSL）方法有望减少注释的要求，但是当数据集大小和注释图像的数量较小时，它们的性能仍然受到限制。利用具有类似解剖结构的现有注释数据集来协助培训，这有可能改善模型的性能。然而，由于目标结构的外观不同甚至成像方式，跨解剖结构域的转移进一步挑战。为了解决这个问题，我们提出了跨解剖结构域适应（CS-CADA）的对比度半监督学习，该学习适应一个模型以在目标结构域中细分相似的结构，这仅需要通过利用一组现有现有的现有的目标域中的限制注释源域中相似结构的注释图像。我们使用特定领域的批归归量表（DSBN）来单独地标准化两个解剖域的特征图，并提出跨域对比度学习策略，以鼓励提取域不变特征。它们被整合到一个自我兼容的均值老师（SE-MT）框架中，以利用具有预测一致性约束的未标记的目标域图像。广泛的实验表明，我们的CS-CADA能够解决具有挑战性的跨解剖结构域移位问题，从而在视网膜血管图像和心脏MR图像的帮助下，在X射线图像中准确分割冠状动脉，并借助底底图像，分别仅给定目标域中的少量注释。

元加强学习（Meta RL）作为元学习思想和强化学习（RL）的组合，使代理商能够使用一些样本适应不同的任务。但是，这种基于抽样的适应也使元rl容易受到对抗攻击的影响。通过操纵Meta RL中抽样过程的奖励反馈，攻击者可以误导代理商从培训经验中建立错误的知识，从而在适应后处理不同的任务时会恶化代理商的绩效。本文为理解这种类型的安全风险提供了游戏理论的基础。特别是，我们正式将采样攻击模型定义为攻击者和代理之间的stackelberg游戏，该游戏产生了最小值公式。它导致了两种在线攻击方案：间歇性攻击和持续攻击，这使攻击者能够学习最佳采样攻击，这是由$ \ epsilon $ -fir-first-first-fort stastary Point定义的，在$ \ MATHCAL {O}内（\ Epsilon^ {-2}）$迭代。这些攻击方案自由地学习了学习的进度，而没有与环境进行额外互动的情况。通过通过数值实验来证实收敛结果，我们观察到攻击者的较小努力可以显着恶化学习绩效，而Minimax方法也可以帮助鲁棒化元素RL算法。

多尺度体系结构和注意力模块在许多基于深度学习的图像脱落方法中都显示出有效性。但是，将这两个组件手动设计和集成到神经网络中需要大量的劳动力和广泛的专业知识。在本文中，高性能多尺度的细心神经体系结构搜索（MANAS）框架是技术开发的。所提出的方法为图像脱落任务的最爱的多个灵活模块制定了新的多尺度注意搜索空间。在搜索空间下，建立了多尺度的细胞，该单元被进一步用于构建功能强大的图像脱落网络。通过基于梯度的搜索算法自动搜索脱毛网络的内部多尺度架构，该算法在某种程度上避免了手动设计的艰巨过程。此外，为了获得强大的图像脱落模型，还提出了一种实用有效的多到一对训练策略，以允许去磨损网络从具有相同背景场景的多个雨天图像中获取足够的背景信息，与此同时，共同优化了包括外部损失，内部损失，建筑正则损失和模型复杂性损失在内的多个损失功能，以实现可靠的损伤性能和可控的模型复杂性。对合成和逼真的雨图像以及下游视觉应用（即反对检测和分割）的广泛实验结果始终证明了我们提出的方法的优越性。

仅使用图像级标签的弱监督语义细分旨在降低分割任务的注释成本。现有方法通常利用类激活图（CAM）来定位伪标签生成的对象区域。但是，凸轮只能发现对象的最歧视部分，从而导致下像素级伪标签。为了解决这个问题，我们提出了一个限制的显着性和内类关系的显着性（I $^2 $ CRC）框架，以协助CAM中激活的对象区域的扩展。具体而言，我们提出了一个显着性指导的类不足的距离模块，以通过将特征对准其类原型来更接近类别内特征。此外，我们提出了一个特定的距离模块，以将类间特征推开，并鼓励对象区域的激活高于背景。除了加强分类网络激活CAM中更多积分对象区域的能力外，我们还引入了一个对象引导的标签细化模块，以完全利用分割预测和初始标签，以获取出色的伪标签。 Pascal VOC 2012和可可数据集的广泛实验很好地证明了I $^2 $ CRC的有效性，而不是其他最先进的对应物。源代码，模型和数据已在\ url {https://github.com/nust-machine-intelligence-laboratory/i2crc}提供。

当训练数据集患有极端阶级失衡时，深度神经网络通常会表现不佳。最近的研究发现，以半监督的方式直接使用分布外数据（即开放式样本）培训将损害概括性能。在这项工作中，我们从理论上表明，从贝叶斯的角度来看，仍然可以利用分发数据来扩大少数群体。基于这种动机，我们提出了一种称为开放采样的新方法，该方法利用开放式嘈杂标签重新平衡培训数据集的班级先验。对于每个开放式实例，标签是​​从我们的预定义分布中取样的，该分布互补，与原始类先验的分布互补。我们从经验上表明，开放采样不仅可以重新平衡阶级先验，还鼓励神经网络学习可分离的表示。广泛的实验表明，我们提出的方法显着优于现有数据重新平衡方法，并可以提高现有最新方法的性能。

非自动性变压器（NAT）是文本生成模型的家族，旨在通过并行预测整个句子来减少解码延迟。但是，这种延迟减少牺牲了捕获从左到右的依赖性的能力，从而使NAT学习非常具有挑战性。在本文中，我们介绍了理论和经验分析，以揭示NAT学习的挑战，并提出统一的观点来了解现有的成功。首先，我们表明，简单地通过最大化可能性来训练NAT可以导致边际分布的近似值，但在代币之间降低了所有依赖关系，在该数据集的条件总相关性可以测量删除的信息。其次，我们在统一的框架中正式化了许多以前的目标，并表明他们的成功可以得出结论，以最大程度地提高代理分布的可能性，从而减少了信息损失。实证研究表明，我们的观点可以解释NAT学习中的现象，并指导新培训方法的设计。

Binaural audio plays a significant role in constructing immersive augmented and virtual realities. As it is expensive to record binaural audio from the real world, synthesizing them from mono audio has attracted increasing attention. This synthesis process involves not only the basic physical warping of the mono audio, but also room reverberations and head/ear related filtrations, which, however, are difficult to accurately simulate in traditional digital signal processing. In this paper, we formulate the synthesis process from a different perspective by decomposing the binaural audio into a common part that shared by the left and right channels as well as a specific part that differs in each channel. Accordingly, we propose BinauralGrad, a novel two-stage framework equipped with diffusion models to synthesize them respectively. Specifically, in the first stage, the common information of the binaural audio is generated with a single-channel diffusion model conditioned on the mono audio, based on which the binaural audio is generated by a two-channel diffusion model in the second stage. Combining this novel perspective of two-stage synthesis with advanced generative models (i.e., the diffusion models),the proposed BinauralGrad is able to generate accurate and high-fidelity binaural audio samples. Experiment results show that on a benchmark dataset, BinauralGrad outperforms the existing baselines by a large margin in terms of both object and subject evaluation metrics (Wave L2: 0.128 vs. 0.157, MOS: 3.80 vs. 3.61). The generated audio samples (https://speechresearch.github.io/binauralgrad) and code (https://github.com/microsoft/NeuralSpeech/tree/master/BinauralGrad) are available online.