创伤性脑损伤(TBI)患者的脑网络分析对于其意识水平评估和预后评估至关重要,这需要分割某些意识相关的大脑区域。但是,由于很难收集TBI患者的手动注释的MR扫描,因此很难构建TBI分割模型。数据增强技术可用于缓解数据稀缺问题。但是,常规数据增强策略(例如空间和强度转化)无法模仿创伤性大脑中的变形和病变,这限制了后续分割任务的性能。为了解决这些问题,我们提出了一种名为TBIGA的新型医学图像授课模型,以通过配对的脑标签图合成TBI MR扫描。我们的TBIGAN方法的主要优势在于,它可以同时生成TBI图像和相应的标签映射,这在以前的医学图像的先前涂上方法中尚未实现。我们首先按照粗到细节的方式在边缘信息的指导下生成成分的图像,然后将合成强度图像用作标签上填充的先验。此外,我们引入了基于注册的模板增强管道,以增加合成图像对的多样性并增强数据增强能力。实验结果表明,提出的TBIGAN方法可以产生具有高质量和有效标签图的足够合成的TBI图像,这可以大大改善与替代方案相比的2D和3D创伤性脑部分割性能。
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旨在估算每个广告接触点在转换旅程中的贡献的多点触摸归因(MTA)对于预算分配和自动广告至关重要。现有方法首先训练模型,以通过历史数据来预测广告旅程的转换概率,并使用反事实预测来计算每个接触点的归因。这些作品的假设是转换预测模型是公正的,即,它可以对任何随机分配的旅程(包括事实和反事实)提供准确的预测。然而,由于根据用户偏好推荐裸露的广告,因此这个假设并不总是存在。用户的这种混杂偏见将导致反事实预测中的分布(OOD)问题,并导致归因中的概念漂移。在本文中,我们定义了因果MTA任务,并提出Causalmta来消除用户偏好的影响。它从系统地消除了静态和动态偏好的混杂偏见,以使用历史数据来学习转换预测模型。我们还提供理论分析,以证明Causalmta可以学习具有足够数据的无偏见模型。电子商务公司的公共数据集和印象数据的广泛实验表明,Causalmta不仅比最先进的方法实现了更好的预测性能,而且还可以在不同的广告渠道上产生有意义的属性信用。
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遇到错误的损耗压缩正成为必不可少的技术,即当今科学项目的成功,并在模拟或仪器数据获取过程中产生了大量数据。它不仅可以显着减少数据大小,而且还可以基于用户指定的错误界限控制压缩错误。自动编码器(AE)模型已被广泛用于图像压缩中,但是很少有基于AE的压缩方法支持遇到错误的功能,这是科学应用所要求的。为了解决这个问题,我们使用卷积自动编码器探索以改善科学数据的错误损失压缩,并提供以下三个关键贡献。 (1)我们对各种自动编码器模型的特性进行了深入的研究,并根据SZ模型开发了基于错误的自动编码器的框架。 (2)我们在设计的基于AE的错误压缩框架中优化了主要阶段的压缩质量,并微调块大小和潜在尺寸,并优化了潜在向量的压缩效率。 (3)我们使用五个现实世界的科学数据集评估了我们提出的解决方案,并将其与其他六项相关作品进行了比较。实验表明,我们的解决方案在测试中的所有压缩机中表现出非常具有竞争性的压缩质量。从绝对的角度来看,与SZ2.1和ZFP相比,在高压比的情况下,它可以获得更好的压缩质量(压缩率和相同数据失真的100%〜800%提高)。
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A further understanding of cause and effect within observational data is critical across many domains, such as economics, health care, public policy, web mining, online advertising, and marketing campaigns. Although significant advances have been made to overcome the challenges in causal effect estimation with observational data, such as missing counterfactual outcomes and selection bias between treatment and control groups, the existing methods mainly focus on source-specific and stationary observational data. Such learning strategies assume that all observational data are already available during the training phase and from only one source. This practical concern of accessibility is ubiquitous in various academic and industrial applications. That's what it boiled down to: in the era of big data, we face new challenges in causal inference with observational data, i.e., the extensibility for incrementally available observational data, the adaptability for extra domain adaptation problem except for the imbalance between treatment and control groups, and the accessibility for an enormous amount of data. In this position paper, we formally define the problem of continual treatment effect estimation, describe its research challenges, and then present possible solutions to this problem. Moreover, we will discuss future research directions on this topic.
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The growing interest in intelligent services and privacy protection for mobile devices has given rise to the widespread application of federated learning in Multi-access Edge Computing (MEC). Diverse user behaviors call for personalized services with heterogeneous Machine Learning (ML) models on different devices. Federated Multi-task Learning (FMTL) is proposed to train related but personalized ML models for different devices, whereas previous works suffer from excessive communication overhead during training and neglect the model heterogeneity among devices in MEC. Introducing knowledge distillation into FMTL can simultaneously enable efficient communication and model heterogeneity among clients, whereas existing methods rely on a public dataset, which is impractical in reality. To tackle this dilemma, Federated MultI-task Distillation for Multi-access Edge CompuTing (FedICT) is proposed. FedICT direct local-global knowledge aloof during bi-directional distillation processes between clients and the server, aiming to enable multi-task clients while alleviating client drift derived from divergent optimization directions of client-side local models. Specifically, FedICT includes Federated Prior Knowledge Distillation (FPKD) and Local Knowledge Adjustment (LKA). FPKD is proposed to reinforce the clients' fitting of local data by introducing prior knowledge of local data distributions. Moreover, LKA is proposed to correct the distillation loss of the server, making the transferred local knowledge better match the generalized representation. Experiments on three datasets show that FedICT significantly outperforms all compared benchmarks in various data heterogeneous and model architecture settings, achieving improved accuracy with less than 1.2% training communication overhead compared with FedAvg and no more than 75% training communication round compared with FedGKT.
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Reinforcement learning (RL) is one of the most important branches of AI. Due to its capacity for self-adaption and decision-making in dynamic environments, reinforcement learning has been widely applied in multiple areas, such as healthcare, data markets, autonomous driving, and robotics. However, some of these applications and systems have been shown to be vulnerable to security or privacy attacks, resulting in unreliable or unstable services. A large number of studies have focused on these security and privacy problems in reinforcement learning. However, few surveys have provided a systematic review and comparison of existing problems and state-of-the-art solutions to keep up with the pace of emerging threats. Accordingly, we herein present such a comprehensive review to explain and summarize the challenges associated with security and privacy in reinforcement learning from a new perspective, namely that of the Markov Decision Process (MDP). In this survey, we first introduce the key concepts related to this area. Next, we cover the security and privacy issues linked to the state, action, environment, and reward function of the MDP process, respectively. We further highlight the special characteristics of security and privacy methodologies related to reinforcement learning. Finally, we discuss the possible future research directions within this area.
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Denoising Diffusion Probabilistic Models (DDPMs) are emerging in text-to-speech (TTS) synthesis because of their strong capability of generating high-fidelity samples. However, their iterative refinement process in high-dimensional data space results in slow inference speed, which restricts their application in real-time systems. Previous works have explored speeding up by minimizing the number of inference steps but at the cost of sample quality. In this work, to improve the inference speed for DDPM-based TTS model while achieving high sample quality, we propose ResGrad, a lightweight diffusion model which learns to refine the output spectrogram of an existing TTS model (e.g., FastSpeech 2) by predicting the residual between the model output and the corresponding ground-truth speech. ResGrad has several advantages: 1) Compare with other acceleration methods for DDPM which need to synthesize speech from scratch, ResGrad reduces the complexity of task by changing the generation target from ground-truth mel-spectrogram to the residual, resulting into a more lightweight model and thus a smaller real-time factor. 2) ResGrad is employed in the inference process of the existing TTS model in a plug-and-play way, without re-training this model. We verify ResGrad on the single-speaker dataset LJSpeech and two more challenging datasets with multiple speakers (LibriTTS) and high sampling rate (VCTK). Experimental results show that in comparison with other speed-up methods of DDPMs: 1) ResGrad achieves better sample quality with the same inference speed measured by real-time factor; 2) with similar speech quality, ResGrad synthesizes speech faster than baseline methods by more than 10 times. Audio samples are available at https://resgrad1.github.io/.
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Face manipulation detection has been receiving a lot of attention for the reliability and security of the face images. Recent studies focus on using auxiliary information or prior knowledge to capture robust manipulation traces, which are shown to be promising. As one of the important face features, the face depth map, which has shown to be effective in other areas such as the face recognition or face detection, is unfortunately paid little attention to in literature for detecting the manipulated face images. In this paper, we explore the possibility of incorporating the face depth map as auxiliary information to tackle the problem of face manipulation detection in real world applications. To this end, we first propose a Face Depth Map Transformer (FDMT) to estimate the face depth map patch by patch from a RGB face image, which is able to capture the local depth anomaly created due to manipulation. The estimated face depth map is then considered as auxiliary information to be integrated with the backbone features using a Multi-head Depth Attention (MDA) mechanism that is newly designed. Various experiments demonstrate the advantage of our proposed method for face manipulation detection.
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The development of deep learning models in medical image analysis is majorly limited by the lack of large-sized and well-annotated datasets. Unsupervised learning does not require labels and is more suitable for solving medical image analysis problems. However, most of the current unsupervised learning methods need to be applied to large datasets. To make unsupervised learning applicable to small datasets, we proposed Swin MAE, which is a masked autoencoder with Swin Transformer as its backbone. Even on a dataset of only a few thousand medical images and without using any pre-trained models, Swin MAE is still able to learn useful semantic features purely from images. It can equal or even slightly outperform the supervised model obtained by Swin Transformer trained on ImageNet in terms of the transfer learning results of downstream tasks. The code will be publicly available soon.
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In this paper, we study the \underline{R}obust \underline{o}ptimization for \underline{se}quence \underline{Net}worked \underline{s}ubmodular maximization (RoseNets) problem. We interweave the robust optimization with the sequence networked submodular maximization. The elements are connected by a directed acyclic graph and the objective function is not submodular on the elements but on the edges in the graph. Under such networked submodular scenario, the impact of removing an element from a sequence depends both on its position in the sequence and in the network. This makes the existing robust algorithms inapplicable. In this paper, we take the first step to study the RoseNets problem. We design a robust greedy algorithm, which is robust against the removal of an arbitrary subset of the selected elements. The approximation ratio of the algorithm depends both on the number of the removed elements and the network topology. We further conduct experiments on real applications of recommendation and link prediction. The experimental results demonstrate the effectiveness of the proposed algorithm.
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