卷积神经网络已使基于医学图像的诊断有了重大改进。但是,越来越明显的是,这些模型在面对虚假的相关性和数据集转移时易受性能降解,例如,领导者(例如,代表性不足的患者群体的表现不足)。在本文中,我们比较了ADNI MRI数据集上的两个分类方案:使用手动选择的体积特征的简单逻辑回归模型,以及对3D MRI数据训练的卷积神经网络。我们在面对不同的数据集拆分,训练集的性别组成和疾病阶段的情况下评估了受过训练的模型的鲁棒性。与其他成像方式中的早期工作相反,我们没有观察到培训数据集中多数组的模型性能的明确模式。取而代之的是,尽管逻辑回归对数据集组成完全可靠,但我们发现,在培训数据集中包括更多女性受试者时,男性和女性受试者的CNN性能通常会提高。我们假设这可能是由于两性病理学的固有差异。此外,在我们的分析中,Logistic回归模型优于3D CNN,强调了基于先验知识的手动特征规范的实用性,以及需要更强大的自动功能选择。
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Automatic Image Cropping is a challenging task with many practical downstream applications. The task is often divided into sub-problems - generating cropping candidates, finding the visually important regions, and determining aesthetics to select the most appealing candidate. Prior approaches model one or more of these sub-problems separately, and often combine them sequentially. We propose a novel convolutional neural network (CNN) based method to crop images directly, without explicitly modeling image aesthetics, evaluating multiple crop candidates, or detecting visually salient regions. Our model is trained on a large dataset of images cropped by experienced editors and can simultaneously predict bounding boxes for multiple fixed aspect ratios. We consider the aspect ratio of the cropped image to be a critical factor that influences aesthetics. Prior approaches for automatic image cropping, did not enforce the aspect ratio of the outputs, likely due to a lack of datasets for this task. We, therefore, benchmark our method on public datasets for two related tasks - first, aesthetic image cropping without regard to aspect ratio, and second, thumbnail generation that requires fixed aspect ratio outputs, but where aesthetics are not crucial. We show that our strategy is competitive with or performs better than existing methods in both these tasks. Furthermore, our one-stage model is easier to train and significantly faster than existing two-stage or end-to-end methods for inference. We present a qualitative evaluation study, and find that our model is able to generalize to diverse images from unseen datasets and often retains compositional properties of the original images after cropping. Our results demonstrate that explicitly modeling image aesthetics or visual attention regions is not necessarily required to build a competitive image cropping algorithm.
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Over the years, sequential Monte Carlo (SMC) and, equivalently, particle filter (PF) theory has gained substantial attention from researchers. However, the performance of the resampling methodology, also known as offspring selection, has not advanced recently. We propose two deterministic offspring selection methods, which strive to minimize the Kullback-Leibler (KL) divergence and the total variation (TV) distance, respectively, between the particle distribution prior and subsequent to the offspring selection. By reducing the statistical distance between the selected offspring and the joint distribution, we obtain a heuristic search procedure that performs superior to a maximum likelihood search in precisely those contexts where the latter performs better than an SMC. For SMC and particle Markov chain Monte Carlo (pMCMC), our proposed offspring selection methods always outperform or compare favorably with the two state-of-the-art resampling schemes on two models commonly used as benchmarks from the literature.
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Earthquakes, fire, and floods often cause structural collapses of buildings. The inspection of damaged buildings poses a high risk for emergency forces or is even impossible, though. We present three recent selected missions of the Robotics Task Force of the German Rescue Robotics Center, where both ground and aerial robots were used to explore destroyed buildings. We describe and reflect the missions as well as the lessons learned that have resulted from them. In order to make robots from research laboratories fit for real operations, realistic test environments were set up for outdoor and indoor use and tested in regular exercises by researchers and emergency forces. Based on this experience, the robots and their control software were significantly improved. Furthermore, top teams of researchers and first responders were formed, each with realistic assessments of the operational and practical suitability of robotic systems.
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Large language models (LLMs) have been shown to be able to perform new tasks based on a few demonstrations or natural language instructions. While these capabilities have led to widespread adoption, most LLMs are developed by resource-rich organizations and are frequently kept from the public. As a step towards democratizing this powerful technology, we present BLOOM, a 176B-parameter open-access language model designed and built thanks to a collaboration of hundreds of researchers. BLOOM is a decoder-only Transformer language model that was trained on the ROOTS corpus, a dataset comprising hundreds of sources in 46 natural and 13 programming languages (59 in total). We find that BLOOM achieves competitive performance on a wide variety of benchmarks, with stronger results after undergoing multitask prompted finetuning. To facilitate future research and applications using LLMs, we publicly release our models and code under the Responsible AI License.
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Many scientific domains gather sufficient labels to train machine algorithms through human-in-the-loop techniques provided by the Zooniverse.org citizen science platform. As the range of projects, task types and data rates increase, acceleration of model training is of paramount concern to focus volunteer effort where most needed. The application of Transfer Learning (TL) between Zooniverse projects holds promise as a solution. However, understanding the effectiveness of TL approaches that pretrain on large-scale generic image sets vs. images with similar characteristics possibly from similar tasks is an open challenge. We apply a generative segmentation model on two Zooniverse project-based data sets: (1) to identify fat droplets in liver cells (FatChecker; FC) and (2) the identification of kelp beds in satellite images (Floating Forests; FF) through transfer learning from the first project. We compare and contrast its performance with a TL model based on the COCO image set, and subsequently with baseline counterparts. We find that both the FC and COCO TL models perform better than the baseline cases when using >75% of the original training sample size. The COCO-based TL model generally performs better than the FC-based one, likely due to its generalized features. Our investigations provide important insights into usage of TL approaches on multi-domain data hosted across different Zooniverse projects, enabling future projects to accelerate task completion.
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Recent 3D-based manipulation methods either directly predict the grasp pose using 3D neural networks, or solve the grasp pose using similar objects retrieved from shape databases. However, the former faces generalizability challenges when testing with new robot arms or unseen objects; and the latter assumes that similar objects exist in the databases. We hypothesize that recent 3D modeling methods provides a path towards building digital replica of the evaluation scene that affords physical simulation and supports robust manipulation algorithm learning. We propose to reconstruct high-quality meshes from real-world point clouds using state-of-the-art neural surface reconstruction method (the Real2Sim step). Because most simulators take meshes for fast simulation, the reconstructed meshes enable grasp pose labels generation without human efforts. The generated labels can train grasp network that performs robustly in the real evaluation scene (the Sim2Real step). In synthetic and real experiments, we show that the Real2Sim2Real pipeline performs better than baseline grasp networks trained with a large dataset and a grasp sampling method with retrieval-based reconstruction. The benefit of the Real2Sim2Real pipeline comes from 1) decoupling scene modeling and grasp sampling into sub-problems, and 2) both sub-problems can be solved with sufficiently high quality using recent 3D learning algorithms and mesh-based physical simulation techniques.
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医学图像分割模型的性能指标用于衡量参考注释和预测之间的一致性。在开发此类模型中,使用了一组通用指标,以使结果更具可比性。但是,公共数据集中的分布与临床实践中遇到的案例之间存在不匹配。许多常见的指标无法衡量这种不匹配的影响,尤其是对于包含不确定,小或空参考注释的临床数据集。因此,可能无法通过此类指标来验证模型在临床上有意义的一致性。评估临床价值的维度包括独立于参考注释量的大小,考虑参考注释的不确定性,体积计和/或位置一致性的奖励以及对空参考注释正确分类的奖励。与普通的公共数据集不同,我们的内部数据集更具代表性。它包含不确定的,小或空的参考注释。我们研究了有关深度学习框架的预测的公开度量指标,以确定哪些设置共同指标可提供有意义的结果。我们将公共基准数据集进行比较而没有不确定,小或空参考注释。该代码将发布。
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噪声的去除或取消对成像和声学具有广泛的应用。在日常生活中,Denoising甚至可能包括对地面真理不忠的生成方面。但是,对于科学应用,denoing必须准确地重现地面真相。在这里,我们展示了如何通过深层卷积神经网络来定位数据,从而以定量精度出现弱信号。特别是,我们研究了晶体材料的X射线衍射。我们证明,弱信号是由电荷排序引起的,在嘈杂的数据中微不足道的信号,在DeNo的数据中变得可见和准确。通过对深度神经网络的监督培训,具有成对的低噪声数据,可以通过监督培训来实现这一成功。这样,神经网络就可以了解噪声的统计特性。我们证明,使用人造噪声(例如泊松和高斯)不会产生这种定量准确的结果。因此,我们的方法说明了一种实用的噪声过滤策略,可以应用于具有挑战性的获取问题。
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隐私已成为机器学习的主要问题。实际上,联合学习是出于隐私问题而激发的,因为它不允许传输私人数据,而仅传输中间更新。但是,联邦学习并不总是保证隐私保护,因为中间更新也可能揭示敏感信息。在本文中,我们对高斯混合模型的联合期望最大化算法进行了明确的信息理论分析,并证明了中间更新可能导致严重的隐私泄漏。为了解决隐私问题,我们提出了一个完全分散的隐私解决方案,该解决方案能够安全地计算每个最大化步骤中的更新。此外,我们考虑了两种不同类型的安全攻击:诚实但有趣而窃听的对手模型。数值验证表明,就准确性和隐私水平而言,与现有方法相比,所提出的方法具有优越的性能。
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