Normalizing flows are a powerful tool for generative modelling, density estimation and posterior reconstruction in Bayesian inverse problems. In this paper, we introduce proximal residual flows, a new architecture of normalizing flows. Based on the fact, that proximal neural networks are by definition averaged operators, we ensure invertibility of certain residual blocks. Moreover, we extend the architecture to conditional proximal residual flows for posterior reconstruction within Bayesian inverse problems. We demonstrate the performance of proximal residual flows on numerical examples.
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仅使用少量数据学习神经网络是一个重要的研究主题,具有巨大的应用潜力。在本文中,我们介绍了基于归一化流量的成像中反问题的变异建模的常规化器。我们的常规器称为PatchNR,涉及在很少的图像的贴片上学习的正常流。特别是,培训独立于考虑的逆问题,因此可以将相同的正规化程序用于在同一类图像上作用的不同前向操作员。通过研究斑块的分布与整个图像类别的分布,我们证明我们的变分模型确实是一种地图方法。如果有其他监督信息,我们的模型可以推广到有条件的补丁。材料图像和低剂量或限量角度计算机断层扫描(CT)的层分辨率的数值示例表明,我们的方法在具有相似假设的方法之间提供了高质量的结果,但仅需要很少的数据。
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标准化流动,扩散归一化流量和变形自动置换器是强大的生成模型。在本文中,我们提供了一个统一的框架来通过马尔可夫链处理这些方法。实际上,我们考虑随机标准化流量作为一对马尔可夫链,满足一些属性,并表明许多用于数据生成的最先进模型适合该框架。马尔可夫链的观点使我们能够将确定性层作为可逆的神经网络和随机层作为大都会加速层,Langevin层和变形自身偏移,以数学上的声音方式。除了具有Langevin层的密度的层,扩散层或变形自身形式,也可以处理与确定性层或大都会加热器层没有密度的层。因此,我们的框架建立了一个有用的数学工具来结合各种方法。
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在本文中,我们在两维图像的超级度之前介绍了Wasserstein补丁。在这里,我们假设我们(另外到了低分辨率观察)的参考图像,其具有与重建的地面真实类似的补丁分布。这种假设是例如使用纹理图像或材料数据时满足。然后,建议的规则器惩罚重建的修补程序分发的$ w_2 $ - 在不同尺度下的一些参考图像的补丁分布。我们通过两维数值示例展示了所提出的规范器的性能。
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为了克服拓扑限制并提高常规流量架构,吴,K \“ohler和No \'e的表达性引入了随机采样方法的随机标准化流程,该流程与随机取样方法相结合的确定性,可学习的流动变换。在本文中,我们考虑随机标准化流量一个马尔可夫链的观点。特别是,我们通过马尔可夫内核替换过渡密度,并通过氡-Nikodym衍生物建立证据,允许以声音方式结合没有密度的分布。此外,我们概括了从后部分布中抽样的结果逆问题所需。通过数值实施例证明了所提出的条件随机标准化流程的性能。
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Machine learning models are typically evaluated by computing similarity with reference annotations and trained by maximizing similarity with such. Especially in the bio-medical domain, annotations are subjective and suffer from low inter- and intra-rater reliability. Since annotations only reflect the annotation entity's interpretation of the real world, this can lead to sub-optimal predictions even though the model achieves high similarity scores. Here, the theoretical concept of Peak Ground Truth (PGT) is introduced. PGT marks the point beyond which an increase in similarity with the reference annotation stops translating to better Real World Model Performance (RWMP). Additionally, a quantitative technique to approximate PGT by computing inter- and intra-rater reliability is proposed. Finally, three categories of PGT-aware strategies to evaluate and improve model performance are reviewed.
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Quaternion valued neural networks experienced rising popularity and interest from researchers in the last years, whereby the derivatives with respect to quaternions needed for optimization are calculated as the sum of the partial derivatives with respect to the real and imaginary parts. However, we can show that product- and chain-rule does not hold with this approach. We solve this by employing the GHRCalculus and derive quaternion backpropagation based on this. Furthermore, we experimentally prove the functionality of the derived quaternion backpropagation.
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Neuromorphic systems require user-friendly software to support the design and optimization of experiments. In this work, we address this need by presenting our development of a machine learning-based modeling framework for the BrainScaleS-2 neuromorphic system. This work represents an improvement over previous efforts, which either focused on the matrix-multiplication mode of BrainScaleS-2 or lacked full automation. Our framework, called hxtorch.snn, enables the hardware-in-the-loop training of spiking neural networks within PyTorch, including support for auto differentiation in a fully-automated hardware experiment workflow. In addition, hxtorch.snn facilitates seamless transitions between emulating on hardware and simulating in software. We demonstrate the capabilities of hxtorch.snn on a classification task using the Yin-Yang dataset employing a gradient-based approach with surrogate gradients and densely sampled membrane observations from the BrainScaleS-2 hardware system.
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Osteoarthritis (OA) is the most prevalent chronic joint disease worldwide, where knee OA takes more than 80% of commonly affected joints. Knee OA is not a curable disease yet, and it affects large columns of patients, making it costly to patients and healthcare systems. Etiology, diagnosis, and treatment of knee OA might be argued by variability in its clinical and physical manifestations. Although knee OA carries a list of well-known terminology aiming to standardize the nomenclature of the diagnosis, prognosis, treatment, and clinical outcomes of the chronic joint disease, in practice there is a wide range of terminology associated with knee OA across different data sources, including but not limited to biomedical literature, clinical notes, healthcare literacy, and health-related social media. Among these data sources, the scientific articles published in the biomedical literature usually make a principled pipeline to study disease. Rapid yet, accurate text mining on large-scale scientific literature may discover novel knowledge and terminology to better understand knee OA and to improve the quality of knee OA diagnosis, prevention, and treatment. The present works aim to utilize artificial neural network strategies to automatically extract vocabularies associated with knee OA diseases. Our finding indicates the feasibility of developing word embedding neural networks for autonomous keyword extraction and abstraction of knee OA.
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Data-centric artificial intelligence (data-centric AI) represents an emerging paradigm emphasizing that the systematic design and engineering of data is essential for building effective and efficient AI-based systems. The objective of this article is to introduce practitioners and researchers from the field of Information Systems (IS) to data-centric AI. We define relevant terms, provide key characteristics to contrast the data-centric paradigm to the model-centric one, and introduce a framework for data-centric AI. We distinguish data-centric AI from related concepts and discuss its longer-term implications for the IS community.
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