Normalizing flow is a class of deep generative models for efficient sampling and density estimation. In practice, the flow often appears as a chain of invertible neural network blocks; to facilitate training, existing works have regularized flow trajectories and designed special network architectures. The current paper develops a neural ODE flow network inspired by the Jordan-Kinderleherer-Otto (JKO) scheme, which allows efficient block-wise training of the residual blocks and avoids inner loops of score matching or variational learning. As the JKO scheme unfolds the dynamic of gradient flow, the proposed model naturally stacks residual network blocks one-by-one, reducing the memory load and difficulty of performing end-to-end training of deep flow networks. We also develop adaptive time reparameterization of the flow network with a progressive refinement of the trajectory in probability space, which improves the model training efficiency and accuracy in practice. Using numerical experiments with synthetic and real data, we show that the proposed JKO-iFlow model achieves similar or better performance in generating new samples compared with existing flow and diffusion models at a significantly reduced computational and memory cost.

This paper studies the distribution estimation of contaminated data by the MoM-GAN method, which combines generative adversarial net (GAN) and median-of-mean (MoM) estimation. We use a deep neural network (DNN) with a ReLU activation function to model the generator and discriminator of the GAN. Theoretically, we derive a non-asymptotic error bound for the DNN-based MoM-GAN estimator measured by integral probability metrics with the $b$-smoothness H\"{o}lder class. The error bound decreases essentially as $n^{-b/p}\vee n^{-1/2}$, where $n$ and $p$ are the sample size and the dimension of input data. We give an algorithm for the MoM-GAN method and implement it through two real applications. The numerical results show that the MoM-GAN outperforms other competitive methods when dealing with contaminated data.

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 present a new distribution-free conformal prediction algorithm for sequential data (e.g., time series), called the \textit{sequential predictive conformal inference} (\texttt{SPCI}). We specifically account for the nature that the time series data are non-exchangeable, and thus many existing conformal prediction algorithms based on temporal residuals are not applicable. The main idea is to exploit the temporal dependence of conformity scores; thus, the past conformity scores contain information about future ones. Then we cast the problem of conformal prediction interval as predicting the quantile of a future residual, given a prediction algorithm. Theoretically, we establish asymptotic valid conditional coverage upon extending consistency analyses in quantile regression. Using simulation and real-data experiments, we demonstrate a significant reduction in interval width of \texttt{SPCI} compared to other existing methods under the desired empirical coverage.

In this paper, we propose a robust election simulation model and independently developed election anomaly detection algorithm that demonstrates the simulation's utility. The simulation generates artificial elections with similar properties and trends as elections from the real world, while giving users control and knowledge over all the important components of the elections. We generate a clean election results dataset without fraud as well as datasets with varying degrees of fraud. We then measure how well the algorithm is able to successfully detect the level of fraud present. The algorithm determines how similar actual election results are as compared to the predicted results from polling and a regression model of other regions that have similar demographics. We use k-means to partition electoral regions into clusters such that demographic homogeneity is maximized among clusters. We then use a novelty detection algorithm implemented as a one-class Support Vector Machine where the clean data is provided in the form of polling predictions and regression predictions. The regression predictions are built from the actual data in such a way that the data supervises itself. We show both the effectiveness of the simulation technique and the machine learning model in its success in identifying fraudulent regions.

We develop an online kernel Cumulative Sum (CUSUM) procedure, which consists of a parallel set of kernel statistics with different window sizes to account for the unknown change-point location. Compared with many existing sliding window-based kernel change-point detection procedures, which correspond to the Shewhart chart-type procedure, the proposed procedure is more sensitive to small changes. We further present a recursive computation of detection statistics, which is crucial for online procedures to achieve a constant computational and memory complexity, such that we do not need to calculate and remember the entire Gram matrix, which can be a computational bottleneck otherwise. We obtain precise analytic approximations of the two fundamental performance metrics, the Average Run Length (ARL) and Expected Detection Delay (EDD). Furthermore, we establish the optimal window size on the order of $\log ({\rm ARL})$ such that there is nearly no power loss compared with an oracle procedure, which is analogous to the classic result for window-limited Generalized Likelihood Ratio (GLR) procedure. We present extensive numerical experiments to validate our theoretical results and the competitive performance of the proposed method.

现代医疗保健系统正在对电子病历（EMR）进行连续自动监视，以识别频率越来越多的不良事件；但是，许多败血症等事件都没有明确阐明前瞻性（即事件链），可用于识别和拦截它的早期不良事件。目前，尚无可靠的框架来发现或描述不良医院事件之前的因果链。临床上相关和可解释的结果需要一个框架，可以（1）推断在EMR数据中发现的多个患者特征（例如，实验室，生命体征等）中的时间相互作用，并且（2）可以识别（s）的模式（s）。到即将发生的不良事件（例如，败血症）。在这项工作中，我们提出了一个线性多元霍克斯进程模型，并与$ g（x）= x^+$链接函数结合起来允许潜在的抑制作用，以恢复Granger Causal（GC）图。我们开发了一个基于两阶段的方案，以最大程度地提高可能性的替代品以估计问题参数。该两相算法可扩展，并通过我们的数值模拟显示有效。随后将其扩展到佐治亚州亚特兰大的Grady医院系统的患者数据集，在那里，合适的Granger Causal图识别出败血症之前的几个高度可解释的链。

Federated学习（FL）最近作为一种增强隐私的工具而受到了极大的关注，可以由多个参与者共同培训机器学习模型。FL的先前工作主要研究了如何在模型培训期间保护标签隐私。但是，FL中的模型评估也可能导致私人标签信息的潜在泄漏。在这项工作中，我们提出了一种评估算法，该算法可以准确计算使用FL中的标签差异隐私（DP）时，可以准确计算广泛使用的AUC（曲线下）度量。通过广泛的实验，我们显示我们的算法可以计算与地面真相相比的准确AUC。

基于多模式方面的情感分类（MABSC）是一项新兴的分类任务，旨在将给定目标的情感分类，例如具有不同模式的数据中提到的实体。在带有文本和图像的典型多模式数据中，以前的方法不能充分利用图像的细颗粒语义，尤其是与文本的语义结合在一起，并且不完全考虑对细粒图像之间的关系进行建模信息和目标，这导致图像的使用不足和不足以识别细粒度的方面和意见。为了应对这些局限性，我们提出了一个新的框架SEQCSG，包括一种构建顺序跨模式语义图和编码器模型的方法。具体而言，我们从原始图像，图像标题和场景图中提取细粒度的信息，并将它们视为跨模式语义图的元素以及文本的令牌。跨模式语义图表示为具有多模式可见矩阵的序列，指示元素之间的关系。为了有效地利用跨模式语义图，我们建议使用目标提示模板的编码器解码器方法。实验结果表明，我们的方法优于现有方法，并在两个标准数据集MABSC上实现了最新方法。进一步的分析证明了每个组件的有效性，我们的模型可以隐含地学习图像的目标和细粒度信息之间的相关性。

手语制作（SLP）旨在将口语语言自动转化为符号序列。 SLP的核心过程是将符号光泽序列转换为其相应的标志姿势序列（G2P）。大多数现有的G2P模型通常以自回归方式执行这种条件的远程生成，这不可避免地导致错误的积累。为了解决这个问题，我们提出了一种量化量子序列序列的生成的矢量量化扩散方法，称为poseVQ扩散，这是一种迭代性非自动入学方法。具体而言，我们首先引入量化量化变量自动编码器（姿势VQVAE）模型，以表示姿势序列作为一系列潜在代码。然后，我们通过最近开发的扩散体系结构的扩展来对潜在离散空间进行建模。为了更好地利用时空信息，我们介绍了一种新颖的体系结构，即CodeUnet，以在离散空间中生成更高质量的姿势序列。此外，利用学习的代码，我们开发了一种新型的顺序k-nearest-neighbours方法，以预测相应的光泽序列的姿势序列的可变长度。因此，与自回旋G2P模型相比，我们的模型具有更快的采样速度，并产生明显更好的结果。与以前的非自动入学G2P方法相比，PoseVQ扩散通过迭代改进改善了预测的结果，从而在SLP评估基准上获得了最新的结果。