数据已成为当今世界上最有价值的资源。随着数据驱动算法的大量扩散,例如基于深度学习的方法,数据的可用性引起了极大的兴趣。在这种情况下,特别需要高质量的培训,验证和测试数据集。体积数据是医学中非常重要的资源,因为它范围从疾病诊断到治疗监测。如果数据集足够,则可以培训模型来帮助医生完成这些任务。不幸的是,在某些情况和应用程序中,大量数据不可用。例如,在医疗领域,罕见疾病和隐私问题可能导致数据可用性受到限制。在非医学领域,获得足够数量的高质量数据的高成本也可能引起人们的关注。解决这些问题的方法可能是生成合成数据,以结合其他更传统的数据增强方法来执行数据增强。因此,关于3D生成对抗网络(GAN)的大多数出版物都在医疗领域内。生成现实合成数据的机制的存在是克服这一挑战的好资产,尤其是在医疗保健中,因为数据必须具有良好的质量并且接近现实,即现实,并且没有隐私问题。在这篇综述中,我们提供了使用GAN生成现实的3D合成数据的作品的摘要。因此,我们概述了具有共同体系结构,优势和缺点的这些领域中基于GAN的方法。我们提出了一种新颖的分类学,评估,挑战和研究机会,以提供医学和其他领域甘恩当前状态的整体概述。
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使用磁共振成像(MRI)的平移大脑研究变得越来越受欢迎,因为动物模型是科学研究的重要组成部分,超高场扫描仪变得更加可用。 MRI的一些缺点是MRI扫描仪可用性,并且执行完整扫描会话所需的时间(通常需要30分钟)。数据保护法和3R道德规则也使得难以为培训深度学习模型创建大型数据集。已经显示了生成的对抗网络(GaN)能够以比其他技术更高的质量执行数据增强。在这项工作中,Alpha-GaN架构用于测试其生成RAT大脑的现实3D MRI扫描的能力。就作者来说,这是第一次基于GAN的方法首次用于临床前数据的数据增强。使用各种定性和定量度量来评估生成的扫描。由4名专家执行的图灵测试表明,生成的扫描可能几乎可以欺骗任何专家。产生的扫描也用于评估它们对对白种物质,灰质和脑脊髓液的大鼠脑分割开发的现有深度学习模型的性能的影响。使用骰子分数进行比较模型。当使用174种实际扫描和348种合成物时,实现了全脑和白质分割的最佳结果,提高了0.0172和0.0129。使用174个真实扫描和87个合成物导致了0.0038和0.0764的灰质和脑脊液细分的改善。因此,通过使用所提出的新归一化层和损耗功能,可以改善生成的RAT MRI扫描的现实主义,并且证明使用数据产生的改进的分割模型比使用传统数据增强改进。
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开发了一个3D深度学习模型(OARNet)并用于在CT图像上描绘28 H&N OAR。 OARNET利用密集连接的网络来检测OAR边界盒,然后在盒子内划定OAR。它将来自任何层的信息重用到后续层,并使用跳过连接来组合来自不同密集块电平的信息来逐步提高描绘精度。培训最多使用最多28名专家手册划定(MD)桨从165 CTS划算。骰子相似度系数(DSC)和第95百分位HAUSDORFF距离(HD95)相对于MD评估了70个其他CT。对MD的平均值,最大和根平均方形剂量差异评估了70cts的56个。 oarnet与UANET,ANATOMYNET和MULTI-ATLAS分段(MAS)进行比较。使用95%置信区间的Wilcoxon签名级别测试用于评估意义。 Wilcoxon签署了排名测试表明,与UANET相比,OARNET改善了(P <0.05)DSC(23/28桨)和HD95(17/28)。 OARNet优于DSC(28/28)和HD95(27/28)的Anatomynet和MAS。与UANET相比,OARNET将中位数DSC改善至0.05和HD95,高达1.5mm。与Anatomynet和MAS相比,OARNET将中位数(DSC,HD95)改为高达(0.08,2.7mm)和(0.17,6.3mm)。 DoSimetry,Oarnet优于Uanet(Dmax 7/28; Dmean 10/28),Anatomynet(Dmax 21/28; Dmean 24/28)和MAS(Dmax 22/28; Dmean 21/28)。 DenSenet架构使用混合方法进行优化,该混合方法执行OAR特定的边界框检测,然后是要素识别。与其他自动描绘方法相比,Oarnet优于或等于所有几何(颞叶L,HD95)和28 H&N OAR的一个剂量(眼睛L,平均剂量)终点,并且优于或者等于所有OAR的Anatomynet和MAS。
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Selecting the number of topics in LDA models is considered to be a difficult task, for which alternative approaches have been proposed. The performance of the recently developed singular Bayesian information criterion (sBIC) is evaluated and compared to the performance of alternative model selection criteria. The sBIC is a generalization of the standard BIC that can be implemented to singular statistical models. The comparison is based on Monte Carlo simulations and carried out for several alternative settings, varying with respect to the number of topics, the number of documents and the size of documents in the corpora. Performance is measured using different criteria which take into account the correct number of topics, but also whether the relevant topics from the DGPs are identified. Practical recommendations for LDA model selection in applications are derived.
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Applying deep learning concepts from image detection and graph theory has greatly advanced protein-ligand binding affinity prediction, a challenge with enormous ramifications for both drug discovery and protein engineering. We build upon these advances by designing a novel deep learning architecture consisting of a 3-dimensional convolutional neural network utilizing channel-wise attention and two graph convolutional networks utilizing attention-based aggregation of node features. HAC-Net (Hybrid Attention-Based Convolutional Neural Network) obtains state-of-the-art results on the PDBbind v.2016 core set, the most widely recognized benchmark in the field. We extensively assess the generalizability of our model using multiple train-test splits, each of which maximizes differences between either protein structures, protein sequences, or ligand extended-connectivity fingerprints. Furthermore, we perform 10-fold cross-validation with a similarity cutoff between SMILES strings of ligands in the training and test sets, and also evaluate the performance of HAC-Net on lower-quality data. We envision that this model can be extended to a broad range of supervised learning problems related to structure-based biomolecular property prediction. All of our software is available as open source at https://github.com/gregory-kyro/HAC-Net/.
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Counterfactual explanation is a common class of methods to make local explanations of machine learning decisions. For a given instance, these methods aim to find the smallest modification of feature values that changes the predicted decision made by a machine learning model. One of the challenges of counterfactual explanation is the efficient generation of realistic counterfactuals. To address this challenge, we propose VCNet-Variational Counter Net-a model architecture that combines a predictor and a counterfactual generator that are jointly trained, for regression or classification tasks. VCNet is able to both generate predictions, and to generate counterfactual explanations without having to solve another minimisation problem. Our contribution is the generation of counterfactuals that are close to the distribution of the predicted class. This is done by learning a variational autoencoder conditionally to the output of the predictor in a join-training fashion. We present an empirical evaluation on tabular datasets and across several interpretability metrics. The results are competitive with the state-of-the-art method.
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Despite their impressive performance on diverse tasks, large language models (LMs) still struggle with tasks requiring rich world knowledge, implying the limitations of relying solely on their parameters to encode a wealth of world knowledge. This paper aims to understand LMs' strengths and limitations in memorizing factual knowledge, by conducting large-scale knowledge probing experiments of 10 models and 4 augmentation methods on PopQA, our new open-domain QA dataset with 14k questions. We find that LMs struggle with less popular factual knowledge, and that scaling fails to appreciably improve memorization of factual knowledge in the tail. We then show that retrieval-augmented LMs largely outperform orders of magnitude larger LMs, while unassisted LMs remain competitive in questions about high-popularity entities. Based on those findings, we devise a simple, yet effective, method for powerful and efficient retrieval-augmented LMs, which retrieves non-parametric memories only when necessary. Experimental results show that this significantly improves models' performance while reducing the inference costs.
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We introduce the Conditional Independence Regression CovariancE (CIRCE), a measure of conditional independence for multivariate continuous-valued variables. CIRCE applies as a regularizer in settings where we wish to learn neural features $\varphi(X)$ of data $X$ to estimate a target $Y$, while being conditionally independent of a distractor $Z$ given $Y$. Both $Z$ and $Y$ are assumed to be continuous-valued but relatively low dimensional, whereas $X$ and its features may be complex and high dimensional. Relevant settings include domain-invariant learning, fairness, and causal learning. The procedure requires just a single ridge regression from $Y$ to kernelized features of $Z$, which can be done in advance. It is then only necessary to enforce independence of $\varphi(X)$ from residuals of this regression, which is possible with attractive estimation properties and consistency guarantees. By contrast, earlier measures of conditional feature dependence require multiple regressions for each step of feature learning, resulting in more severe bias and variance, and greater computational cost. When sufficiently rich features are used, we establish that CIRCE is zero if and only if $\varphi(X) \perp \!\!\! \perp Z \mid Y$. In experiments, we show superior performance to previous methods on challenging benchmarks, including learning conditionally invariant image features.
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We study inductive matrix completion (matrix completion with side information) under an i.i.d. subgaussian noise assumption at a low noise regime, with uniform sampling of the entries. We obtain for the first time generalization bounds with the following three properties: (1) they scale like the standard deviation of the noise and in particular approach zero in the exact recovery case; (2) even in the presence of noise, they converge to zero when the sample size approaches infinity; and (3) for a fixed dimension of the side information, they only have a logarithmic dependence on the size of the matrix. Differently from many works in approximate recovery, we present results both for bounded Lipschitz losses and for the absolute loss, with the latter relying on Talagrand-type inequalities. The proofs create a bridge between two approaches to the theoretical analysis of matrix completion, since they consist in a combination of techniques from both the exact recovery literature and the approximate recovery literature.
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This paper describes Waymo's Collision Avoidance Testing (CAT) methodology: a scenario-based testing method that evaluates the safety of the Waymo Driver Automated Driving Systems' (ADS) intended functionality in conflict situations initiated by other road users that require urgent evasive maneuvers. Because SAE Level 4 ADS are responsible for the dynamic driving task (DDT), when engaged, without immediate human intervention, evaluating a Level 4 ADS using scenario-based testing is difficult due to the potentially infinite number of operational scenarios in which hazardous situations may unfold. To that end, in this paper we first describe the safety test objectives for the CAT methodology, including the collision and serious injury metrics and the reference behavior model representing a non-impaired eyes on conflict human driver used to form an acceptance criterion. Afterward, we introduce the process for identifying potentially hazardous situations from a combination of human data, ADS testing data, and expert knowledge about the product design and associated Operational Design Domain (ODD). The test allocation and execution strategy is presented next, which exclusively utilize simulations constructed from sensor data collected on a test track, real-world driving, or from simulated sensor data. The paper concludes with the presentation of results from applying CAT to the fully autonomous ride-hailing service that Waymo operates in San Francisco, California and Phoenix, Arizona. The iterative nature of scenario identification, combined with over ten years of experience of on-road testing, results in a scenario database that converges to a representative set of responder role scenarios for a given ODD. Using Waymo's virtual test platform, which is calibrated to data collected as part of many years of ADS development, the CAT methodology provides a robust and scalable safety evaluation.
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