有监督的深度学习算法具有自动化筛查,监视和分级的医学图像的巨大潜力。但是,培训表现模型通常需要大量的标记数据,这在医疗领域几乎无法获得。自我监督的对比框架通过首先从未标记的图像中学习来放松这种依赖性。在这项工作中,我们表明使用两种对比方法进行了预处理,即SIMCLR和BYOL,就与年龄相关的黄斑变性(AMD)的临床评估有关深度学习的实用性。在实验中,使用两个大型临床数据集,其中包含7,912名患者的170,427个光学相干断层扫描(OCT)图像,我们评估了从AMD阶段和类型分类到功能性终点的七个下游任务,从七个下游任务进行预处理,从在标签较少的七个任务中,六个任务中有六个显着增加。但是,标准的对比框架具有两个已知的弱点,这些弱点不利于医疗领域的预处理。用于创建正面对比对的几种图像转换不适用于灰度医学扫描。此外,医学图像通常描绘了相同的解剖区域和疾病的严重程度,从而导致许多误导性负面对。为了解决这些问题,我们开发了一种新颖的元数据增强方法,该方法利用了丰富的固有可用患者信息集。为此,我们采用了患者身份,眼睛位置(即左或右)和时间序列数据的记录,以指示典型的不可知的对比关系。通过利用这种经常被忽视的信息,我们元数据增强的对比预处理可带来进一步的好处,并且在下游七个任务中有五个任务中的五个中的五分之一。
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光学相干断层扫描(OCT)是一种非侵入性的3D模态,广泛用于视网膜的眼科。在OCT上实现自动化的解剖学视网膜层分割对于检测和监测不同视网膜疾病(如年龄相关的黄斑病(AMD)或糖尿病性视网膜病)很重要。但是,大多数最先进的层分割方法基于纯监督的深度学习,需要大量的像素级注释数据,这些数据昂贵且难以获得。考虑到这一点,我们将半监督的范式介绍到视网膜层分割任务中,该任务利用大规模未标记数据集中存在的信息以及解剖学先验。特别是,一种新型的完全可区分的方法用于将表面位置回归转换为像素结构化分割,从而使以耦合方式同时使用1D表面和2D层表示来训练模型。特别是,这些2D分割被用作解剖因素,与学习的样式因子一起组成了用于重建输入图像的分离表示。同时,我们建议一组解剖学先验,以改善有限的标记数据时,可以改善网络训练。我们在使用中间和湿amd的现实世界中的扫描数据集上证明了我们的方法在使用我们的完整训练集时优于最先进带有标记数据的一部分。
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最近的对比学习方法在低标签制度中实现了最新的。但是,培训需要大批量和重型增强,以创建图像的多个视图。使用非对抗性方法,负面因素被隐式地纳入损失中,允许不同的图像和模态作为对。尽管医学成像中的元信息(即年龄,性别)很丰富,但注释又嘈杂,容易出现阶级失衡。在这项工作中,我们使用纵向光学相干断层扫描(OCT)数据集利用了已经存在的时间信息(来自患者的不同访问),但使用时间知情的非对抗性损失(TINC),而没有增加复杂性和对负面对的需求。此外,我们的新颖配对方案可以避免重大增强,并将时间信息隐含地纳入对。最后,这些从训练中学到的表示在预测时间信息对于下游任务至关重要的情况下更为成功。更具体地说,我们的模型优于现有模型,可以预测从中期与年龄相关的黄斑变性(AMD)到晚期湿AMD阶段的转化风险。
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We present a Machine Learning (ML) study case to illustrate the challenges of clinical translation for a real-time AI-empowered echocardiography system with data of ICU patients in LMICs. Such ML case study includes data preparation, curation and labelling from 2D Ultrasound videos of 31 ICU patients in LMICs and model selection, validation and deployment of three thinner neural networks to classify apical four-chamber view. Results of the ML heuristics showed the promising implementation, validation and application of thinner networks to classify 4CV with limited datasets. We conclude this work mentioning the need for (a) datasets to improve diversity of demographics, diseases, and (b) the need of further investigations of thinner models to be run and implemented in low-cost hardware to be clinically translated in the ICU in LMICs. The code and other resources to reproduce this work are available at https://github.com/vital-ultrasound/ai-assisted-echocardiography-for-low-resource-countries.
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Automated plot generation is the challenge of generating a sequence of events that will be perceived by readers as the plot of a coherent story. Traditional symbolic planners plan a story from a goal state and guarantee logical causal plot coherence but rely on a library of hand-crafted actions with their preconditions and effects. This closed world setting limits the length and diversity of what symbolic planners can generate. On the other hand, pre-trained neural language models can generate stories with great diversity, while being generally incapable of ending a story in a specified manner and can have trouble maintaining coherence. In this paper, we present an approach to story plot generation that unifies causal planning with neural language models. We propose to use commonsense knowledge extracted from large language models to recursively expand a story plot in a backward chaining fashion. Specifically, our system infers the preconditions for events in the story and then events that will cause those conditions to become true. We performed automatic evaluation to measure narrative coherence as indicated by the ability to answer questions about whether different events in the story are causally related to other events. Results indicate that our proposed method produces more coherent plotlines than several strong baselines.
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Common disabilities like stroke and spinal cord injuries may cause loss of motor function in hands. They can be treated with robot assisted rehabilitation techniques, like continuously opening and closing the hand with help of a robot, in a cheaper, and less time consuming manner than traditional methods. Hand exoskeletons are developed to assist rehabilitation, but their bulky nature brings with it certain challenges. As soft robots use elastomeric and fabric elements rather than heavy links, and operate with pneumatic, hydraulic or tendon based rather than traditional rotary or linear motors, soft hand exoskeletons are deemed a better option in relation to rehabilitation.
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Modal verbs (e.g., "can", "should", or "must") occur highly frequently in scientific articles. Decoding their function is not straightforward: they are often used for hedging, but they may also denote abilities and restrictions. Understanding their meaning is important for various NLP tasks such as writing assistance or accurate information extraction from scientific text. To foster research on the usage of modals in this genre, we introduce the MIST (Modals In Scientific Text) dataset, which contains 3737 modal instances in five scientific domains annotated for their semantic, pragmatic, or rhetorical function. We systematically evaluate a set of competitive neural architectures on MIST. Transfer experiments reveal that leveraging non-scientific data is of limited benefit for modeling the distinctions in MIST. Our corpus analysis provides evidence that scientific communities differ in their usage of modal verbs, yet, classifiers trained on scientific data generalize to some extent to unseen scientific domains.
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Stock and flow diagrams are already an important tool in epidemiology, but category theory lets us go further and treat these diagrams as mathematical entities in their own right. In this chapter we use communicable disease models created with our software, StockFlow.jl, to explain the benefits of the categorical approach. We first explain the category of stock-flow diagrams, and note the clear separation between the syntax of these diagrams and their semantics, demonstrating three examples of semantics already implemented in the software: ODEs, causal loop diagrams, and system structure diagrams. We then turn to two methods for building large stock-flow diagrams from smaller ones in a modular fashion: composition and stratification. Finally, we introduce the open-source ModelCollab software for diagram-based collaborative modeling. The graphical user interface of this web-based software lets modelers take advantage of the ideas discussed here without any knowledge of their categorical foundations.
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Controlled automated story generation seeks to generate natural language stories satisfying constraints from natural language critiques or preferences. Existing methods to control for story preference utilize prompt engineering which is labor intensive and often inconsistent. They may also use logit-manipulation methods which require annotated datasets to exist for the desired attributes. To address these issues, we first train a contrastive bi-encoder model to align stories with corresponding human critiques, named CARP, building a general purpose preference model. This is subsequently used as a reward function to fine-tune a generative language model via reinforcement learning. However, simply fine-tuning a generative language model with a contrastive reward model does not always reliably result in a story generation system capable of generating stories that meet user preferences. To increase story generation robustness we further fine-tune the contrastive reward model using a prompt-learning technique. A human participant study is then conducted comparing generations from our full system, ablations, and two baselines. We show that the full fine-tuning pipeline results in a story generator preferred over a LLM 20x as large as well as logit-based methods. This motivates the use of contrastive learning for general purpose human preference modeling.
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Covid-19在大流行的不同阶段对公众构成了不成比例的心理健康后果。我们使用一种计算方法来捕获引发在线社区对大流行的焦虑的特定方面,并研究这些方面如何随时间变化。首先,我们使用主题分析在R/covid19 \ _support的Reddit帖子样本($ n $ = 86)中确定了九个焦虑(SOA)。然后,我们通过在手动注释的样本($ n $ = 793)上训练Reddit用户的焦虑来自动将SOA标记在较大的年代样本中($ n $ = 6,535)。 9个SOA与最近开发的大流行焦虑测量量表中的项目保持一致。我们观察到,在大流行的前八个月,Reddit用户对健康风险的担忧仍然很高。尽管案件激增稍后发生,但这些担忧却大大减少了。通常,随着大流行的进展,用户的语言披露了SOA的强烈强度。但是,在本研究涵盖的整个期间,人们对心理健康的担忧和未来稳步增长。人们还倾向于使用更强烈的语言来描述心理健康问题,而不是健康风险或死亡问题。我们的结果表明,尽管Covid-19逐渐削弱,但由于适当的对策而逐渐削弱了作为健康威胁,但该在线小组的心理健康状况并不一定会改善。我们的系统为人口健康和流行病学学者奠定了基础,以及时检查引起大流行焦虑的方面。
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