The lack of standardization is a prominent issue in magnetic resonance (MR) imaging. This often causes undesired contrast variations due to differences in hardware and acquisition parameters. In recent years, MR harmonization using image synthesis with disentanglement has been proposed to compensate for the undesired contrast variations. Despite the success of existing methods, we argue that three major improvements can be made. First, most existing methods are built upon the assumption that multi-contrast MR images of the same subject share the same anatomy. This assumption is questionable since different MR contrasts are specialized to highlight different anatomical features. Second, these methods often require a fixed set of MR contrasts for training (e.g., both Tw-weighted and T2-weighted images must be available), which limits their applicability. Third, existing methods generally are sensitive to imaging artifacts. In this paper, we present a novel approach, Harmonization with Attention-based Contrast, Anatomy, and Artifact Awareness (HACA3), to address these three issues. We first propose an anatomy fusion module that enables HACA3 to respect the anatomical differences between MR contrasts. HACA3 is also robust to imaging artifacts and can be trained and applied to any set of MR contrasts. Experiments show that HACA3 achieves state-of-the-art performance under multiple image quality metrics. We also demonstrate the applicability of HACA3 on downstream tasks with diverse MR datasets acquired from 21 sites with different field strengths, scanner platforms, and acquisition protocols.
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超越地球轨道的人类空间勘探将涉及大量距离和持续时间的任务。为了有效减轻无数空间健康危害,数据和空间健康系统的范式转移是实现地球独立性的,而不是Earth-Reliance所必需的。有希望在生物学和健康的人工智能和机器学习领域的发展可以解决这些需求。我们提出了一个适当的自主和智能精密空间健康系统,可以监控,汇总和评估生物医学状态;分析和预测个性化不良健康结果;适应并响应新累积的数据;并提供对其船员医务人员的个人深度空间机组人员和迭代决策支持的预防性,可操作和及时的见解。在这里,我们介绍了美国国家航空航天局组织的研讨会的建议摘要,以便在太空生物学和健康中未来的人工智能应用。在未来十年,生物监测技术,生物标志科学,航天器硬件,智能软件和简化的数据管理必须成熟,并编织成精确的空间健康系统,以使人类在深空中茁壮成长。
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空间生物学研究旨在了解太空飞行对生物的根本影响,制定支持深度空间探索的基础知识,最终生物工程航天器和栖息地稳定植物,农作物,微生物,动物和人类的生态系统,为持续的多行星寿命稳定。要提高这些目标,该领域利用了来自星空和地下模拟研究的实验,平台,数据和模型生物。由于研究扩展到低地球轨道之外,实验和平台必须是最大自主,光,敏捷和智能化,以加快知识发现。在这里,我们介绍了由美国国家航空航天局的人工智能,机器学习和建模应用程序组织的研讨会的建议摘要,这些应用程序为这些空间生物学挑战提供了关键解决方案。在未来十年中,将人工智能融入太空生物学领域将深化天空效应的生物学理解,促进预测性建模和分析,支持最大自主和可重复的实验,并有效地管理星载数据和元数据,所有目标使生活能够在深空中茁壮成长。
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我们研究了清单可解放的平均估计问题,而对手可能会破坏大多数数据集。具体来说,我们在$ \ mathbb {r} ^ $和参数$ 0 <\ alpha <\ frac 1 2 $中给出了一个$ $ n $ points的$ t $ points。$ \ alpha $ -flaction的点$ t $是iid来自乖巧的分发$ \ Mathcal {D} $的样本,剩余的$(1- \ alpha)$ - 分数是任意的。目标是输出小型的vectors列表,其中至少一个接近$ \ mathcal {d} $的均值。我们开发新的算法,用于列出可解码的平均值估计,实现几乎最佳的统计保证,运行时间$ O(n ^ {1 + \ epsilon_0} d)$,适用于任何固定$ \ epsilon_0> 0 $。所有先前的此问题算法都有额外的多项式因素在$ \ frac 1 \ alpha $。我们与额外技术一起利用此结果,以获得用于聚类混合物的第一个近几个线性时间算法,用于分开的良好表现良好的分布,几乎匹配谱方法的统计保证。先前的聚类算法本身依赖于$ k $ -pca的应用程序,从而产生$ \ omega(n d k)$的运行时。这标志着近二十年来这个基本统计问题的第一次运行时间改进。我们的方法的起点是基于单次矩阵乘法权重激发电位减少的$ \ Alpha \至1 $制度中的新颖和更简单的近线性时间较强的估计算法。在Diakonikolas等人的迭代多滤波技术的背景下,我们迫切地利用了这种新的算法框架。 '18,'20,提供一种使用一维投影的同时群集和下群点的方法 - 因此,绕过先前算法所需的$ k $ -pca子程序。
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The recent increase in public and academic interest in preserving biodiversity has led to the growth of the field of conservation technology. This field involves designing and constructing tools that utilize technology to aid in the conservation of wildlife. In this article, we will use case studies to demonstrate the importance of designing conservation tools with human-wildlife interaction in mind and provide a framework for creating successful tools. These case studies include a range of complexities, from simple cat collars to machine learning and game theory methodologies. Our goal is to introduce and inform current and future researchers in the field of conservation technology and provide references for educating the next generation of conservation technologists. Conservation technology not only has the potential to benefit biodiversity but also has broader impacts on fields such as sustainability and environmental protection. By using innovative technologies to address conservation challenges, we can find more effective and efficient solutions to protect and preserve our planet's resources.
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We present the interpretable meta neural ordinary differential equation (iMODE) method to rapidly learn generalizable (i.e., not parameter-specific) dynamics from trajectories of multiple dynamical systems that vary in their physical parameters. The iMODE method learns meta-knowledge, the functional variations of the force field of dynamical system instances without knowing the physical parameters, by adopting a bi-level optimization framework: an outer level capturing the common force field form among studied dynamical system instances and an inner level adapting to individual system instances. A priori physical knowledge can be conveniently embedded in the neural network architecture as inductive bias, such as conservative force field and Euclidean symmetry. With the learned meta-knowledge, iMODE can model an unseen system within seconds, and inversely reveal knowledge on the physical parameters of a system, or as a Neural Gauge to "measure" the physical parameters of an unseen system with observed trajectories. We test the validity of the iMODE method on bistable, double pendulum, Van der Pol, Slinky, and reaction-diffusion systems.
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While the brain connectivity network can inform the understanding and diagnosis of developmental dyslexia, its cause-effect relationships have not yet enough been examined. Employing electroencephalography signals and band-limited white noise stimulus at 4.8 Hz (prosodic-syllabic frequency), we measure the phase Granger causalities among channels to identify differences between dyslexic learners and controls, thereby proposing a method to calculate directional connectivity. As causal relationships run in both directions, we explore three scenarios, namely channels' activity as sources, as sinks, and in total. Our proposed method can be used for both classification and exploratory analysis. In all scenarios, we find confirmation of the established right-lateralized Theta sampling network anomaly, in line with the temporal sampling framework's assumption of oscillatory differences in the Theta and Gamma bands. Further, we show that this anomaly primarily occurs in the causal relationships of channels acting as sinks, where it is significantly more pronounced than when only total activity is observed. In the sink scenario, our classifier obtains 0.84 and 0.88 accuracy and 0.87 and 0.93 AUC for the Theta and Gamma bands, respectively.
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Variational autoencoders model high-dimensional data by positing low-dimensional latent variables that are mapped through a flexible distribution parametrized by a neural network. Unfortunately, variational autoencoders often suffer from posterior collapse: the posterior of the latent variables is equal to its prior, rendering the variational autoencoder useless as a means to produce meaningful representations. Existing approaches to posterior collapse often attribute it to the use of neural networks or optimization issues due to variational approximation. In this paper, we consider posterior collapse as a problem of latent variable non-identifiability. We prove that the posterior collapses if and only if the latent variables are non-identifiable in the generative model. This fact implies that posterior collapse is not a phenomenon specific to the use of flexible distributions or approximate inference. Rather, it can occur in classical probabilistic models even with exact inference, which we also demonstrate. Based on these results, we propose a class of latent-identifiable variational autoencoders, deep generative models which enforce identifiability without sacrificing flexibility. This model class resolves the problem of latent variable non-identifiability by leveraging bijective Brenier maps and parameterizing them with input convex neural networks, without special variational inference objectives or optimization tricks. Across synthetic and real datasets, latent-identifiable variational autoencoders outperform existing methods in mitigating posterior collapse and providing meaningful representations of the data.
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There are multiple scales of abstraction from which we can describe the same image, depending on whether we are focusing on fine-grained details or a more global attribute of the image. In brain mapping, learning to automatically parse images to build representations of both small-scale features (e.g., the presence of cells or blood vessels) and global properties of an image (e.g., which brain region the image comes from) is a crucial and open challenge. However, most existing datasets and benchmarks for neuroanatomy consider only a single downstream task at a time. To bridge this gap, we introduce a new dataset, annotations, and multiple downstream tasks that provide diverse ways to readout information about brain structure and architecture from the same image. Our multi-task neuroimaging benchmark (MTNeuro) is built on volumetric, micrometer-resolution X-ray microtomography images spanning a large thalamocortical section of mouse brain, encompassing multiple cortical and subcortical regions. We generated a number of different prediction challenges and evaluated several supervised and self-supervised models for brain-region prediction and pixel-level semantic segmentation of microstructures. Our experiments not only highlight the rich heterogeneity of this dataset, but also provide insights into how self-supervised approaches can be used to learn representations that capture multiple attributes of a single image and perform well on a variety of downstream tasks. Datasets, code, and pre-trained baseline models are provided at: https://mtneuro.github.io/ .
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