在本文中,我们考虑使用Palentir在两个和三个维度中对分段常数对象的恢复和重建,这是相对于当前最新ART的显着增强的参数级别集(PALS)模型。本文的主要贡献是一种新的PALS公式,它仅需要一个单个级别的函数来恢复具有具有多个未知对比度的分段常数对象的场景。我们的模型比当前的多对抗性,多对象问题提供了明显的优势,所有这些问题都需要多个级别集并明确估计对比度大小。给定对比度上的上限和下限,我们的方法能够以任何对比度分布恢复对象,并消除需要知道给定场景中的对比度或其值的需求。我们提供了一个迭代过程,以找到这些空间变化的对比度限制。相对于使用径向基函数(RBF)的大多数PAL方法,我们的模型利用了非异型基函数,从而扩展了给定复杂性的PAL模型可以近似的形状类别。最后,Palentir改善了作为参数识别过程一部分所需的Jacobian矩阵的条件,因此通过控制PALS扩展系数的幅度来加速优化方法,固定基本函数的中心,以及参数映射到图像映射的唯一性,由新参数化提供。我们使用X射线计算机断层扫描,弥漫性光学断层扫描(DOT),Denoising,DeonConvolution问题的2D和3D变体证明了新方法的性能。应用于实验性稀疏CT数据和具有不同类型噪声的模拟数据,以进一步验证所提出的方法。
translated by 谷歌翻译
To apply federated learning to drug discovery we developed a novel platform in the context of European Innovative Medicines Initiative (IMI) project MELLODDY (grant n{\deg}831472), which was comprised of 10 pharmaceutical companies, academic research labs, large industrial companies and startups. The MELLODDY platform was the first industry-scale platform to enable the creation of a global federated model for drug discovery without sharing the confidential data sets of the individual partners. The federated model was trained on the platform by aggregating the gradients of all contributing partners in a cryptographic, secure way following each training iteration. The platform was deployed on an Amazon Web Services (AWS) multi-account architecture running Kubernetes clusters in private subnets. Organisationally, the roles of the different partners were codified as different rights and permissions on the platform and administrated in a decentralized way. The MELLODDY platform generated new scientific discoveries which are described in a companion paper.
translated by 谷歌翻译
在本文中,我们介绍Bayesldm,这是一个用于贝叶斯纵向数据建模的系统,该系统由高级建模语言组成,具有针对复杂的多变量时间序列数据建模的特定功能,并与编译器相结合,可以生成优化的概率程序代码,以在指定模型中执行指定的推理。 Bayesldm支持贝叶斯网络模型的建模,其特定关注动态贝叶斯网络(DBN)的高效,声明性规范。 Bayesldm编译器将模型规范与可用数据和输出代码相结合,用于执行贝叶斯推断,以同时处理丢失的数据,同时处理未知模型参数。这些功能有可能通过抽象产生计算有效的概率推断代码的过程来显着加速域中的迭代建模工作流,这些迭代建模工作流程涉及复杂纵向数据的分析。我们描述了Bayesldm系统组件,评估表示和推理优化的效率,并提供了该系统在分析异质和部分观察到的移动健康数据的应用示例。
translated by 谷歌翻译
磁共振光谱成像(MRSI)是量化体内代谢物的必不可少的工具,但是低空间分辨率限制了其临床应用。基于深度学习的超分辨率方法为改善MRSI的空间分辨率提供了有希望的结果,但是与实验获得的高分辨率图像相比,超级分辨图像通常是模糊的。已经使用生成对抗网络进行了尝试,以提高图像视觉质量。在这项工作中,我们考虑了另一种类型的生成模型,即基于流的模型,与对抗网络相比,训练更稳定和可解释。具体而言,我们提出了一个基于流动的增强器网络,以提高超分辨率MRSI的视觉质量。与以前的基于流的模型不同,我们的增强器网络包含了来自其他图像模式(MRI)的解剖信息,并使用可学习的基础分布。此外,我们施加指南丢失和数据一致性丢失,以鼓励网络在保持高忠诚度的同时以高视觉质量生成图像。从25名高级神经胶质瘤患者获得的1H-MRSI数据集上进行的实验表明,我们的增强子网络的表现优于对抗网络和基线基线方法。我们的方法还允许视觉质量调整和不确定性估计。
translated by 谷歌翻译
语言模型既展示了定量的改进,又展示了新的定性功能,随着规模的增加。尽管它们具有潜在的变革性影响,但这些新能力的特征却很差。为了为未来的研究提供信息,为破坏性的新模型能力做准备,并改善社会有害的效果,至关重要的是,我们必须了解目前和近乎未来的能力和语言模型的局限性。为了应对这一挑战,我们介绍了超越模仿游戏基准(Big Bench)。 Big Bench目前由204个任务组成,由132家机构的442位作者贡献。任务主题是多样的,从语言学,儿童发展,数学,常识性推理,生物学,物理学,社会偏见,软件开发等等。 Big-Bench专注于被认为超出当前语言模型的功能的任务。我们评估了OpenAI的GPT型号,Google内部密集变压器体系结构和大型基础上的开关稀疏变压器的行为,跨越了数百万到数十亿个参数。此外,一个人类专家评估者团队执行了所有任务,以提供强大的基准。研究结果包括:模型性能和校准都随规模改善,但绝对的术语(以及与评估者的性能相比);在模型类中的性能非常相似,尽管带有稀疏性。逐渐和预测的任务通常涉及大量知识或记忆成分,而在临界规模上表现出“突破性”行为的任务通常涉及多个步骤或组成部分或脆性指标;社交偏见通常会随着含糊不清的环境而随着规模而增加,但这可以通过提示来改善。
translated by 谷歌翻译
使用单视图2D照片仅集合,无监督的高质量多视图 - 一致的图像和3D形状一直是一个长期存在的挑战。现有的3D GAN是计算密集型的,也是没有3D-一致的近似;前者限制了所生成的图像的质量和分辨率,并且后者对多视图一致性和形状质量产生不利影响。在这项工作中,我们提高了3D GAN的计算效率和图像质量,而无需依赖这些近似。为此目的,我们介绍了一种表现力的混合明确隐式网络架构,与其他设计选择一起,不仅可以实时合成高分辨率多视图一致图像,而且还产生高质量的3D几何形状。通过解耦特征生成和神经渲染,我们的框架能够利用最先进的2D CNN生成器,例如Stylega2,并继承它们的效率和表现力。在其他实验中,我们展示了与FFHQ和AFHQ猫的最先进的3D感知合成。
translated by 谷歌翻译
Non-linear state-space models, also known as general hidden Markov models, are ubiquitous in statistical machine learning, being the most classical generative models for serial data and sequences in general. The particle-based, rapid incremental smoother PaRIS is a sequential Monte Carlo (SMC) technique allowing for efficient online approximation of expectations of additive functionals under the smoothing distribution in these models. Such expectations appear naturally in several learning contexts, such as likelihood estimation (MLE) and Markov score climbing (MSC). PARIS has linear computational complexity, limited memory requirements and comes with non-asymptotic bounds, convergence results and stability guarantees. Still, being based on self-normalised importance sampling, the PaRIS estimator is biased. Our first contribution is to design a novel additive smoothing algorithm, the Parisian particle Gibbs PPG sampler, which can be viewed as a PaRIS algorithm driven by conditional SMC moves, resulting in bias-reduced estimates of the targeted quantities. We substantiate the PPG algorithm with theoretical results, including new bounds on bias and variance as well as deviation inequalities. Our second contribution is to apply PPG in a learning framework, covering MLE and MSC as special examples. In this context, we establish, under standard assumptions, non-asymptotic bounds highlighting the value of bias reduction and the implicit Rao--Blackwellization of PPG. These are the first non-asymptotic results of this kind in this setting. We illustrate our theoretical results with numerical experiments supporting our claims.
translated by 谷歌翻译
While the capabilities of autonomous systems have been steadily improving in recent years, these systems still struggle to rapidly explore previously unknown environments without the aid of GPS-assisted navigation. The DARPA Subterranean (SubT) Challenge aimed to fast track the development of autonomous exploration systems by evaluating their performance in real-world underground search-and-rescue scenarios. Subterranean environments present a plethora of challenges for robotic systems, such as limited communications, complex topology, visually-degraded sensing, and harsh terrain. The presented solution enables long-term autonomy with minimal human supervision by combining a powerful and independent single-agent autonomy stack, with higher level mission management operating over a flexible mesh network. The autonomy suite deployed on quadruped and wheeled robots was fully independent, freeing the human supervision to loosely supervise the mission and make high-impact strategic decisions. We also discuss lessons learned from fielding our system at the SubT Final Event, relating to vehicle versatility, system adaptability, and re-configurable communications.
translated by 谷歌翻译
This paper introduces a novel algorithm, the Perturbed Proximal Preconditioned SPIDER algorithm (3P-SPIDER), designed to solve finite sum non-convex composite optimization. It is a stochastic Variable Metric Forward-Backward algorithm, which allows approximate preconditioned forward operator and uses a variable metric proximity operator as the backward operator; it also proposes a mini-batch strategy with variance reduction to address the finite sum setting. We show that 3P-SPIDER extends some Stochastic preconditioned Gradient Descent-based algorithms and some Incremental Expectation Maximization algorithms to composite optimization and to the case the forward operator can not be computed in closed form. We also provide an explicit control of convergence in expectation of 3P-SPIDER, and study its complexity in order to satisfy the epsilon-approximate stationary condition. Our results are the first to combine the composite non-convex optimization setting, a variance reduction technique to tackle the finite sum setting by using a minibatch strategy and, to allow deterministic or random approximations of the preconditioned forward operator. Finally, through an application to inference in a logistic regression model with random effects, we numerically compare 3P-SPIDER to other stochastic forward-backward algorithms and discuss the role of some design parameters of 3P-SPIDER.
translated by 谷歌翻译
Landing an unmanned aerial vehicle unmanned aerial vehicle (UAV) on top of an unmanned surface vehicle (USV) in harsh open waters is a challenging problem, owing to forces that can damage the UAV due to a severe roll and/or pitch angle of the USV during touchdown. To tackle this, we propose a novel model predictive control (MPC) approach enabling a UAV to land autonomously on a USV in these harsh conditions. The MPC employs a novel objective function and an online decomposition of the oscillatory motion of the vessel to predict, attempt, and accomplish the landing during near-zero tilt of the landing platform. The nonlinear prediction of the motion of the vessel is performed using visual data from an onboard camera. Therefore, the system does not require any communication with the USV or a control station. The proposed method was analyzed in numerous robotics simulations in harsh and extreme conditions and further validated in various real-world scenarios.
translated by 谷歌翻译