结构分布,即组合空间的分布,通常用于学习观察到数据的潜在概率表示。然而,缩放这些模型是由高计算和内存复杂度相对于潜在表示的大小的瓶颈。诸如隐藏的马尔可夫模型(HMMS)和概率的无内容语法(PCFG)的常见模型在隐藏状态的数量中需要时间和空间二次和立方。这项工作展示了一种简单的方法来降低大类结构化模型的计算和内存复杂性。我们展示通过将中央推理步骤视为矩阵 - 矢量产品,并使用低秩约束,我们可以通过等级进行模型表达性和速度。用神经参数化结构化模型进行语言建模,复音音乐建模,无监督语法诱导和视频建模的实验表明,我们的方法在提供实用加速度的同时匹配大状态空间的标准模型的准确性。
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Despite the huge advancement in knowledge discovery and data mining techniques, the X-ray diffraction (XRD) analysis process has mostly remained untouched and still involves manual investigation, comparison, and verification. Due to the large volume of XRD samples from high-throughput XRD experiments, it has become impossible for domain scientists to process them manually. Recently, they have started leveraging standard clustering techniques, to reduce the XRD pattern representations requiring manual efforts for labeling and verification. Nevertheless, these standard clustering techniques do not handle problem-specific aspects such as peak shifting, adjacent peaks, background noise, and mixed phases; hence, resulting in incorrect composition-phase diagrams that complicate further steps. Here, we leverage data mining techniques along with domain expertise to handle these issues. In this paper, we introduce an incremental phase mapping approach based on binary peak representations using a new threshold based fuzzy dissimilarity measure. The proposed approach first applies an incremental phase computation algorithm on discrete binary peak representation of XRD samples, followed by hierarchical clustering or manual merging of similar pure phases to obtain the final composition-phase diagram. We evaluate our method on the composition space of two ternary alloy systems- Co-Ni-Ta and Co-Ti-Ta. Our results are verified by domain scientists and closely resembles the manually computed ground-truth composition-phase diagrams. The proposed approach takes us closer towards achieving the goal of complete end-to-end automated XRD analysis.
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To analyze this characteristic of vulnerability, we developed an automated deep learning method for detecting microvessels in intravascular optical coherence tomography (IVOCT) images. A total of 8,403 IVOCT image frames from 85 lesions and 37 normal segments were analyzed. Manual annotation was done using a dedicated software (OCTOPUS) previously developed by our group. Data augmentation in the polar (r,{\theta}) domain was applied to raw IVOCT images to ensure that microvessels appear at all possible angles. Pre-processing methods included guidewire/shadow detection, lumen segmentation, pixel shifting, and noise reduction. DeepLab v3+ was used to segment microvessel candidates. A bounding box on each candidate was classified as either microvessel or non-microvessel using a shallow convolutional neural network. For better classification, we used data augmentation (i.e., angle rotation) on bounding boxes with a microvessel during network training. Data augmentation and pre-processing steps improved microvessel segmentation performance significantly, yielding a method with Dice of 0.71+/-0.10 and pixel-wise sensitivity/specificity of 87.7+/-6.6%/99.8+/-0.1%. The network for classifying microvessels from candidates performed exceptionally well, with sensitivity of 99.5+/-0.3%, specificity of 98.8+/-1.0%, and accuracy of 99.1+/-0.5%. The classification step eliminated the majority of residual false positives, and the Dice coefficient increased from 0.71 to 0.73. In addition, our method produced 698 image frames with microvessels present, compared to 730 from manual analysis, representing a 4.4% difference. When compared to the manual method, the automated method improved microvessel continuity, implying improved segmentation performance. The method will be useful for research purposes as well as potential future treatment planning.
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尽管电子健康记录是生物医学研究的丰富数据来源,但这些系统并未在医疗环境中统一地实施,并且由于医疗保健碎片化和孤立的电子健康记录之间缺乏互操作性,可能缺少大量数据。考虑到缺少数据的案例的删除可能会在随后的分析中引起严重的偏见,因此,一些作者更喜欢采用多重插补策略来恢复缺失的信息。不幸的是,尽管几项文献作品已经通过使用现在可以自由研究的任何不同的多个归档算法记录了有希望的结果,但尚无共识,MI算法效果最好。除了选择MI策略之外,归纳算法及其应用程序设置的选择也至关重要且具有挑战性。在本文中,受鲁宾和范布伦的开创性作品的启发,我们提出了一个方法学框架,可以应用于评估和比较多种多个插补技术,旨在选择用于计算临床研究工作中最有效的推断。我们的框架已被应用于验证和扩展较大的队列,这是我们在先前的文献研究中提出的结果,我们在其中评估了关键患者的描述符和Covid-19的影响在2型糖尿病患者中的影响,其数据为2型糖尿病,其数据为2型糖尿病由国家共同队列合作飞地提供。
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我们研究了在两人零和马尔可夫游戏中找到NASH平衡的问题。由于其作为最小值优化程序的表述,解决该问题的自然方法是以交替的方式对每个玩家进行梯度下降/上升。但是,由于基本目标函数的非跨性别/非障碍性,该方法的理论理解是有限的。在我们的论文中,我们考虑解决马尔可夫游戏的熵登记变体。正则化将结构引入了优化景观中,从而使解决方案更加可识别,并允许更有效地解决问题。我们的主要贡献是表明,在正则化参数的正确选择下,梯度下降算法会收敛到原始未注册问题的NASH平衡。我们明确表征了我们算法的最后一个迭代的有限时间性能,该算法的梯度下降上升算法的现有收敛界限大大改善了而没有正则化。最后,我们通过数值模拟来补充分析,以说明算法的加速收敛性。
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贝叶斯工作流程通常需要引入滋扰参数,但对于核心科学建模,需要访问边缘后部密度。在这项工作中,我们使用掩盖的自回归流量和内核密度估计器封装边缘后部,使我们能够计算边际kullback-leibler脱离器和边缘贝叶斯模型尺寸,此外还可以生成样品和计算边际对数概率。我们将其应用于暗能量调查的局部宇宙学示例和全局21cm信号实验。除了计算边缘贝叶斯统计数据外,这项工作对于在贝叶斯实验设计,复杂的先验建模和似然仿真中进一步应用也很重要。该技术可在PIP可容纳的代码人造黄油中公开获得。
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Thin-cap fibroatheroma (TCFA) and plaque rupture have been recognized as the most frequent risk factor for thrombosis and acute coronary syndrome. Intravascular optical coherence tomography (IVOCT) can identify TCFA and assess cap thickness, which provides an opportunity to assess plaque vulnerability. We developed an automated method that can detect lipidous plaque and assess fibrous cap thickness in IVOCT images. This study analyzed a total of 4,360 IVOCT image frames of 77 lesions among 41 patients. To improve segmentation performance, preprocessing included lumen segmentation, pixel-shifting, and noise filtering on the raw polar (r, theta) IVOCT images. We used the DeepLab-v3 plus deep learning model to classify lipidous plaque pixels. After lipid detection, we automatically detected the outer border of the fibrous cap using a special dynamic programming algorithm and assessed the cap thickness. Our method provided excellent discriminability of lipid plaque with a sensitivity of 85.8% and A-line Dice coefficient of 0.837. By comparing lipid angle measurements between two analysts following editing of our automated software, we found good agreement by Bland-Altman analysis (difference 6.7+/-17 degree; mean 196 degree). Our method accurately detected the fibrous cap from the detected lipid plaque. Automated analysis required a significant modification for only 5.5% frames. Furthermore, our method showed a good agreement of fibrous cap thickness between two analysts with Bland-Altman analysis (4.2+/-14.6 micron; mean 175 micron), indicating little bias between users and good reproducibility of the measurement. We developed a fully automated method for fibrous cap quantification in IVOCT images, resulting in good agreement with determinations by analysts. The method has great potential to enable highly automated, repeatable, and comprehensive evaluations of TCFAs.
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我们考虑了折现成本约束的马尔可夫决策过程(CMDP)策略优化问题,其中代理商试图最大化折扣累计奖励,但受到折扣累积公用事业的许多限制。为了解决这个受约束的优化程序,我们研究了经典原始偶性方法的在线参与者 - 批判性变体,其中使用来自基本时间变化的马尔可夫过程产生的单个轨迹的样品估算了原始功能和双重函数的梯度。这种在线原始双重自然参与者批评算法维护并迭代更新三个变量:双变量(或拉格朗日乘数),一个原始变量(或actor)以及用于估算原始变量和偶变量的梯度的评论变量。这些变量同时更新,但在不同的时间尺度上(使用不同的步骤尺寸),它们都相互交织在一起。我们的主要贡献是得出该算法与CMDP问题全局最佳收敛的有限时间分析。具体而言,我们表明,在适当的步骤中,最佳差距和约束违规的情况下,以$ \ mathcal {o}(1/k^{1/6})$的价格收敛到零,其中k是数字。迭代。据我们所知,本文是第一个研究用于解决CMDP问题的在线原始偶发参与者方法的有限时间复杂性。我们还通过数值模拟来验证该算法的有效性。
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在本文中,我们介绍了四种突出的恶意软件检测工具的科学评估,以帮助组织提出两个主要问题:基于ML的工具在多大程度上对以前和从未见过的文件进行了准确的分类?是否值得购买网络级恶意软件检测器?为了识别弱点,我们针对各种文件类型的总计3,536个文件(2,554或72 \%恶意,982或28 \%良性)测试了每个工具,包括数百个恶意零日,polyglots和apt-style-style style文件,在多个协议上交付。我们介绍了有关检测时间和准确性的统计结果,请考虑互补分析(一起使用多个工具),并提供了近期成本效益评估程序的两种新颖应用。尽管基于ML的工具在检测零日文件和可执行文件方面更有效,但基于签名的工具仍然是总体上更好的选择。两种基于网络的工具都与任何一种主机工具配对时都可以进行大量(模拟)节省,但两者在HTTP或SMTP以外的协议上都显示出较差的检测率。我们的结果表明,所有四个工具都具有几乎完美的精度但令人震惊的召回率,尤其是在可执行文件和Office文件以外的文件类型上 - 未检测到37%的恶意软件,包括所有Polyglot文件。给出了研究人员的优先事项,并给出了最终用户的外卖。
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我们研究了随机近似的分散变体,这是一种数据驱动的方法,用于在嘈杂的测量中找到操作员的根。一个具有自己的操作员和数据观察的代理网络,合作地通过分散的通信图找到了聚合操作员的固定点。我们的主要贡献是在从马尔可夫过程中采样时在每个代理下观察到的数据时,对这种分散的随机近似方法提供有限的时间分析;这种缺乏独立性使迭代率偏向和(可能)无限。在相当标准的假设下,我们表明所提出方法的收敛速率与样本是独立的基本相同,仅由对数因子的差异而不同,该对数因素是说明了马尔可夫过程的混合时间。我们的分析中的关键思想是引入一种新型的Razumikhin-Lyapunov函数,该功能是由用于分析延迟普通微分方程的稳定性的一种动机。我们还讨论了拟议方法在多代理系统中许多有趣的学习问题上的应用。
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