Alignment

对齐
  • 文章类型: Journal Article
    从二维截面的堆叠中重建三维(3D)微结构体积,该二维截面是通过串联切片结合316L奥氏体不锈钢的电子背散射衍射(EBSD)映射获得的。提出了一种新的对齐算法,称为线性平移,通过最小化指标(LTMI),通过参考平坦且位于{111}平面上的相干孪生边界来减少相邻部分之间的平移失准。平坦孪晶边界的测量取向与{111}平面的测量取向之间的角度差被用作对准操作的准确性的指示符。该指标通过三角形刻面的质心的线性平移而最小化,在不受EBSD图的面内步长限制的距离处构成晶界。因此,可以有效减少平移失准的系统趋势。本文提出的LTMI对准程序有效地校正了在使用连续切片方法制备的3D-EBSD数据上由其他方法保留的未对准。显著提高了区分相干和非相干孪生边界的准确性。
    A three-dimensional (3D) microstructural volume is reconstructed from a stack of two-dimensional sections which was obtained by serial sectioning coupled with electron back scattering diffraction (EBSD) mapping of a 316L austenitic stainless steel. A new alignment algorithm named linear translation by minimising the indicator (LTMI) is proposed to reduce the translational misalignments between adjacent sections by referencing to coherent twin boundaries which are flat and lying on {111} planes. The angular difference between the measured orientation of a flat twin boundary and that of the {111} plane is used as an indicator of the accuracy of the alignment operations. This indicator is minimised through linear translations of the centroids of triangular facets, which constitute grain boundaries at a distance not restricted by the in-plane step size of the EBSD maps. And hence the systematic trend in the translational misalignments can be effectively reduced. The LTMI alignment procedure proposed herein effectively corrects the misalignments remained by other methods on a 3D-EBSD data prepared using serial sectioning methods. The accuracy in distinguishing between coherent and incoherent twin boundaries is significantly improved.
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  • 文章类型: Journal Article
    单粒子低温电子显微镜(EM)是一种从单个大分子的许多嘈杂的二维投影图像中确定大分子的三维结构的方法,这些大分子的取向和位置是随机且未知的。图像的方向分配问题激发了一般多参考对齐的工作。最近推出的非独特游戏框架提供了一种表示理论方法来对齐紧凑的群体,并提供了一个凸松弛,在某些情况下,该凸松弛被表述为具有全局最优性证书的半定程序。冷冻EM的一个巨大机会是研究异质样品,含有两种或两种以上不同类别或构象的分子。利用这个机会提出了一个算法挑战:确定每个粒子的类别和方向。我们将多参考对齐推广到对齐和分类问题,并且我们建议将非唯一游戏扩展到同时对齐和分类的问题,目的是同时对低温EM图像进行分类并在各自的类别中对齐。
    Single particle cryo-electron microscopy (EM) is a method for determining the 3-D structure of macromolecules from many noisy 2-D projection images of individual macromolecules whose orientations and positions are random and unknown. The problem of orientation assignment for the images motivated work on general multireference alignment. The recently introduced non-unique games framework provides a representation theoretic approach to alignment over compact groups, and offers a convex relaxation which is formulated as semidefinite programs with certificates of global optimality under certain circumstances. One of the great opportunities in cryo-EM is studying heterogeneous samples, containing two or more distinct classes or conformations of molecules. Taking advantage of this opportunity presents an algorithmic challenge: determining both the class and orientation of each particle. We generalize multireference alignment to a problem of alignment and classification, and we propose to extend non-unique games to the problem of simultaneous alignment and classification with the goal of simultaneously classifying cryo-EM images and aligning them within their respective classes.
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  • 文章类型: Journal Article
    在大脑中,功能连接形成一个网络,其拓扑组织可以通过图论网络诊断来描述。这些包括社区结构的特征,如模块化和参与系数,已被证明在童年和青春期的过程中会发生变化。为了研究功能网络的这种变化是否与发育过程中认知表现的变化有关,网络研究通常依赖于预处理参数的任意选择,特别是网络边缘的比例阈值。因为参数的选择会影响网络诊断的值,因此下游的结论,我们建议通过将网络诊断概念化为参数的函数来规避这种选择。与单一值相反,网络诊断曲线在多个尺度上描述了连接体拓扑结构-从最强边缘的最稀疏组到整个边缘集。为了将这些曲线与执行函数和其他协变量联系起来,我们使用标量函数回归,比以前在网络神经科学中使用的基于功能数据的模型更灵活。然后,我们考虑网络之间的系统差异如何表现为诊断曲线的错位,并因此提出了一种监督曲线对齐方法,该方法结合了其他变量的辅助信息。我们的算法通过迭代执行函数回归和对齐,受到惩罚,和非线性似然优化。所说明的方法有可能提高神经科学研究的可解释性和可泛化性,其目标是研究函数和标量值度量的混合之间的异质性。
    In the brain, functional connections form a network whose topological organization can be described by graph-theoretic network diagnostics. These include characterizations of the community structure, such as modularity and participation coefficient, which have been shown to change over the course of childhood and adolescence. To investigate if such changes in the functional network are associated with changes in cognitive performance during development, network studies often rely on an arbitrary choice of preprocessing parameters, in particular the proportional threshold of network edges. Because the choice of parameter can impact the value of the network diagnostic, and therefore downstream conclusions, we propose to circumvent that choice by conceptualizing the network diagnostic as a function of the parameter. As opposed to a single value, a network diagnostic curve describes the connectome topology at multiple scales-from the sparsest group of the strongest edges to the entire edge set. To relate these curves to executive function and other covariates, we use scalar-on-function regression, which is more flexible than previous functional data-based models used in network neuroscience. We then consider how systematic differences between networks can manifest in misalignment of diagnostic curves, and consequently propose a supervised curve alignment method that incorporates auxiliary information from other variables. Our algorithm performs both functional regression and alignment via an iterative, penalized, and nonlinear likelihood optimization. The illustrated method has the potential to improve the interpretability and generalizability of neuroscience studies where the goal is to study heterogeneity among a mixture of function- and scalar-valued measures.
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  • 文章类型: Journal Article
    汽车行业主动安全系统的快速发展和自动驾驶的研究要求可靠,高精度传感器,提供有关周围环境和其他道路使用者行为的丰富信息。在实践中,总是有一些非零的安装错位,即,传感器安装在车辆上的角度不准确。必须进一步以编程方式(在软件中)准确估计和补偿这种未对准。在雷达的情况下,不精确的安装可能会导致不正确/不准确的目标信息,跟踪算法的问题,或者从目标反射的能量减少。应当以两种方式减轻传感器未对准:通过经由未对准角的估计值校正不准确的对准角,或者如果未对准超出操作范围,则警告系统的其他部件潜在的传感器劣化。这项工作分析了未对准对雷达传感器和其他系统组件的影响。在数学上证明的垂直错位雷达的例子中,行人可检测性下降到最大范围的三分之一。此外,数学推导的航向估计误差证明了数据融合对数据关联的影响。仿真结果表明,失准角度呈指数增加了错误轨道分裂的风险。此外,本文对雷达对准技术进行了全面回顾,主要在专利文献中发现,并实现了一个基线算法,以及建议的关键绩效指标(KPI),以方便其他研究人员的比较。
    The rapid development of active safety systems in the automotive industry and research in autonomous driving requires reliable, high-precision sensors that provide rich information about the surrounding environment and the behaviour of other road users. In practice, there is always some non-zero mounting misalignment, i.e., angular inaccuracy in a sensor\'s mounting on a vehicle. It is essential to accurately estimate and compensate for this misalignment further programmatically (in software). In the case of radars, imprecise mounting may result in incorrect/inaccurate target information, problems with the tracking algorithm, or a decrease in the power reflected from the target. Sensor misalignment should be mitigated in two ways: through the correction of an inaccurate alignment angle via the estimated value of the misalignment angle or alerting other components of the system of potential sensor degradation if the misalignment is beyond the operational range. This work analyses misalignment\'s influences on radar sensors and other system components. In the mathematically proven example of a vertically misaligned radar, pedestrian detectability dropped to one-third of the maximum range. In addition, mathematically derived heading estimation errors demonstrate the impact on data association in data fusion. The simulation results presented show that the angle of misalignment exponentially increases the risk of false track splitting. Additionally, the paper presents a comprehensive review of radar alignment techniques, mostly found in the patent literature, and implements a baseline algorithm, along with suggested key performance indicators (KPIs) to facilitate comparisons for other researchers.
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  • 文章类型: Journal Article
    背景:空间转录组学(ST)正在促进我们对复杂组织和生物体的理解。然而,构建稳健的聚类算法以在单个组织切片中定义空间相干区域,并对齐或整合源自不同来源的多个组织切片以进行必要的下游分析仍然具有挑战性。众多的集群,对齐,集成方法是通过利用ST数据的空间信息专门为ST数据设计的。缺乏全面的基准研究使方法的选择和未来的方法开发变得复杂。
    结果:在这项研究中,我们系统地对各种最先进的算法进行基准测试,使用各种大小不同的真实和模拟数据集,技术,物种,和复杂性。我们使用不同的定量和定性指标和分析来分析每种方法的优缺点,包括空间聚类准确性和连续性的八个指标,均匀流形逼近和投影可视化,逐层和逐点对准精度,和三维重建,旨在评估方法性能和数据质量。用于评估的代码可在我们的GitHub上找到。此外,我们提供在线笔记本教程和文档,以促进所有基准测试结果的复制,并支持新方法和新数据集的研究。
    结论:我们的分析得出了涵盖多个方面的全面建议,帮助用户为他们的特定需求选择最佳工具,并指导未来的方法开发。
    BACKGROUND: Spatial transcriptomics (ST) is advancing our understanding of complex tissues and organisms. However, building a robust clustering algorithm to define spatially coherent regions in a single tissue slice and aligning or integrating multiple tissue slices originating from diverse sources for essential downstream analyses remains challenging. Numerous clustering, alignment, and integration methods have been specifically designed for ST data by leveraging its spatial information. The absence of comprehensive benchmark studies complicates the selection of methods and future method development.
    RESULTS: In this study, we systematically benchmark a variety of state-of-the-art algorithms with a wide range of real and simulated datasets of varying sizes, technologies, species, and complexity. We analyze the strengths and weaknesses of each method using diverse quantitative and qualitative metrics and analyses, including eight metrics for spatial clustering accuracy and contiguity, uniform manifold approximation and projection visualization, layer-wise and spot-to-spot alignment accuracy, and 3D reconstruction, which are designed to assess method performance as well as data quality. The code used for evaluation is available on our GitHub. Additionally, we provide online notebook tutorials and documentation to facilitate the reproduction of all benchmarking results and to support the study of new methods and new datasets.
    CONCLUSIONS: Our analyses lead to comprehensive recommendations that cover multiple aspects, helping users to select optimal tools for their specific needs and guide future method development.
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  • 文章类型: Journal Article
    患有神经肌肉病变的个体通常被规定为踝足矫形器(AFO),以通过减少踝关节和下肢的病理运动来改善他们的步态力学。AFO可以抵抗或协助过度或缺乏导致跳闸的肌肉力量,不稳定性,和缓慢低效的步态。然而,选择具有机械特性的合适的AFO,在步态周期的某些阶段限制病理性踝关节运动,同时在其他阶段促进有效的踝关节运动,需要谨慎的临床决策。这项研究的目的是提出一种明确的方法,用于在临床环境中调整多功能关节型AFO。次要目的是概述支持这种方法的证据,并确定文献中的空白作为未来研究的潜在领域。一类新兴的AFO,多功能铰接式AFO,提供允许更全面的功能,迭代,和AFO踝关节对齐的可逆调整和对踝关节运动的阻力。然而,在临床环境中没有标准的方法来应用和优化这些治疗设备。在这里,我们提出了一种证据指导的方法,适用于在临床环境中调整多功能关节型AFO。给出了特征载荷-挠度曲线,以说明多功能铰接式AFO的理想但复杂的阻力角行为。引用研究来证明这些机械特性如何帮助减轻特定的病理性踝关节和膝关节运动学和动力学。提供的证据支持系统调整高抗性的效果,可对齐,铰接式AFO以解决在患有神经肌肉疾病的个体中观察到的许多典型的病理力学模式。已发布的支持算法大多数决策点的证据在证据中具有已识别的差距。此外,给出了两个假设的案例示例,以说明该方法在优化多功能铰接式AFO以治疗特定步态病理力学中的应用。该方法被提出作为一种证据指导的系统方法,用于调整多功能关节式AFO。它利用观察到的步态偏差映射到AFO对准和阻力设置的特定变化,作为患有复杂神经肌肉步态障碍的个体的矫正治疗的临床工具。
    Individuals with neuromuscular pathologies are often prescribed an ankle-foot orthosis (AFO) to improve their gait mechanics by decreasing pathological movements of the ankle and lower limb. AFOs can resist or assist excessive or absent muscular forces that lead to tripping, instability, and slow inefficient gait. However, selecting the appropriate AFO with mechanical characteristics, which limit pathological ankle motion in certain phases of the gait cycle while facilitating effective ankle movement during other phases, requires careful clinical decision-making. The aim of this study is to propose an explicit methodology for the adjustment of multi-function articulated AFOs in clinical settings. A secondary aim is to outline the evidence supporting this methodology and to identify gaps in the literature as potential areas for future research. An emerging class of AFO, the multi-function articulated AFO, offers features that permit more comprehensive, iterative, and reversible adjustments of AFO ankle alignment and resistance to ankle motion. However, no standard method exists for the application and optimization of these therapeutic devices in the clinical setting. Here we propose an evidence-guided methodology applicable to the adjustment of multi-function articulated AFOs in the clinical setting. Characteristic load-deflection curves are given to illustrate the idealized yet complex resistance-angle behavior of multi-function articulated AFOs. Research is cited to demonstrate how these mechanical characteristics can help mitigate specific pathologic ankle and knee kinematics and kinetics. Evidence is presented to support the effects of systematic adjustment of high resistance, alignable, articulated AFOs to address many typical pathomechanical patterns observed in individuals with neuromuscular disorders. The published evidence supporting most decision points of the algorithm is presented with identified gaps in the evidence. In addition, two hypothetical case examples are given to illustrate the application of the method in optimizing multi-function articulated AFOs for treating specific gait pathomechanics. This method is proposed as an evidence-guided systematic approach for the adjustment of multi-function articulated AFOs. It utilizes observed gait deviations mapped to specific changes in AFO alignment and resistance settings as a clinical tool in orthotic treatment for individuals with complex neuromuscular gait disorders.
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  • 文章类型: Journal Article
    在这一章中,我们概述了一种分析元基因组数据的方法,专注于使用新型生物信息学软件工具评估差异酶表达和代谢途径活性,EMPathways2.分析流程从源自测序仪的原始数据开始,并以酶表达的输出和代谢途径活性的估计结束。初始步骤涉及使用Bowtie2比对从RNA-Seq数据组装的特定转录组,并使用IsoEM2获取基因表达数据。随后,管道继续进行输入数据的质量评估和预处理,确保对酶及其差异调节的准确估计。预处理阶段完成后,EMPathways2被用来破译基因之间复杂的关系,酶,和路径。已提供包含示例数据的在线存储库,以及自定义Python脚本,旨在修改管道内程序的输出,以进行各种下游分析。本章重点介绍了使用EMPathways2的技术方面和实际应用,它促进了转录组数据分析的进步,并有助于更深入地了解生命系统背后的复杂调节机制。
    In this chapter, we outline an approach to analyzing metatranscriptomic data, focusing on the assessment of differential enzyme expression and metabolic pathway activities using a novel bioinformatics software tool, EMPathways2. The analysis pipeline commences with raw data originating from a sequencer and concludes with an output of enzyme expressions and an estimate of metabolic pathway activities. The initial step involves aligning specific transcriptomes assembled from RNA-Seq data using Bowtie2 and acquiring gene expression data with IsoEM2. Subsequently, the pipeline proceeds to quality assessment and preprocessing of the input data, ensuring accurate estimates of enzymes and their differential regulation. Upon completion of the preprocessing stage, EMPathways2 is employed to decipher the intricate relationships between genes, enzymes, and pathways. An online repository containing sample data has been made available, alongside custom Python scripts designed to modify the output of the programs within the pipeline for diverse downstream analyses. This chapter highlights the technical aspects and practical applications of using EMPathways2, which facilitates the advancement of transcriptome data analysis and contributes to a deeper understanding of the complex regulatory mechanisms underlying living systems.
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  • 文章类型: Journal Article
    在这一章中,我们提供了一个分析RNA-Seq数据的既定管道,其中涉及从测序仪获得的原始数据开始的逐步流程,并最终鉴定具有功能特征的差异表达基因。管道分为三段,每个处理分析过程的关键阶段。第一部分涵盖了管道的初始步骤,包括下载感兴趣的数据和进行质量控制评估。评估可确保用于分析的数据可靠且适用于下游分析。在第二部分,进行基因水平量化,这需要定量样品中基因的表达水平。第三部分也是最后一部分重点是差异表达分析,这涉及比较两种或多种条件之间的基因表达水平。该步骤有助于鉴定在不同实验条件下在表达水平上显示显著差异的基因。为了促进可访问性和可重复性,我们提供了一个包含所有脚本和文件的在线存储库。此外,自定义脚本可用,使用户能够为各种下游分析修改管道的输出。通过遵循这个管道,研究人员可以有效地分析RNA-Seq数据,并获得对基因表达模式的有价值的见解,此外,对生物过程的理解。
    In this chapter, we present an established pipeline for analyzing RNA-Seq data, which involves a step-by-step flow starting from raw data obtained from a sequencer and culminating in the identification of differentially expressed genes with their functional characterization. The pipeline is divided into three sections, each addressing crucial stages of the analysis process. The first section covers the initial steps of the pipeline, including downloading of the data of interest and performing quality control assessment. Assessment ensures that the data used for analysis is reliable and suitable for downstream analyses. In the second section, gene-level quantification is performed, which entails quantification of expression levels of genes in the samples. The third and final section is focused on differential expression analysis, which involves comparing gene expression levels between two or more conditions. This step helps identify genes that show significant differences in expression levels under different experimental conditions. To facilitate accessibility and reproducibility, we have provided an online repository containing all scripts and files. Additionally, custom scripts are available, enabling users to modify the pipeline\'s output for various downstream analyses. By following this pipeline, researchers can effectively analyze RNA-Seq data and gain valuable insights into gene expression patterns and, furthermore, the understanding of biological processes.
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  • 文章类型: Journal Article
    目前寻求各向异性凝胶结构的可控形成以开发具有新型质地的食品。这里,我们使用单向冷冻来产生琼脂凝胶,该凝胶由细长且对齐的孔的蜂窝状多孔网络组成。定制的Peltier系统允许控制整个琼脂凝胶的冷冻前沿速度。与测试的较慢的冷冻速度(2µm/s)相比,较高的冷冻速度(10µm/s)导致较小的孔径。纹理分析突出表明,当在轴向压缩时,凝胶中的杨氏模量明显高于径向-单向冻结的直接结果。质子自旋-自旋弛豫时间显示,在具有较大孔的单向冷冻凝胶中,水的迁移率更大。这项研究是开发具有可调微观结构和质地的各向异性水胶体凝胶的基础。
    The controllable formation of anisotropic gel structures is presently sought for the development of foods with novel textures. Here, we used unidirectional freezing to generate agar gels consisting of a honeycomb-like porous network of elongated and aligned pores. A custom-built Peltier system allowed for control of the freezing front velocity throughout the agar gels. A higher freezing velocity (10 µm/s) led to smaller pore sizes compared to the slower freezing velocity tested (2 µm/s). Texture analysis highlighted the significantly higher Young\'s modulus in the gels when compressed in the axial vs. radial direction - a direct consequence of the unidirectional freezing. The proton spin-spin relaxation time revealed greater water mobility in the unidirectionally frozen gel with larger pores. This study serves as the basis for the development of anisotropic hydrocolloid gels with a tunable microstructure and texture.
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  • 文章类型: Journal Article
    本文介绍了一项研究,该研究评估了化学计量学在质量控制背景下对咖啡样品进行分类的应用。高分辨率和准确的质量测量用作基于像素的正交偏最小二乘判别分析(OPLS-DA)模型的输入。使用FT-Orbitrap®质量分析仪,通过组合顶空固相微萃取和气相色谱-高分辨率质谱(GC-HRMS)的全自动工作流程获得组成数据。以准确的质量测量为中心的工作流程已成功用于组型分析,为完全依赖MS相似性搜索的方法提供了替代方案。预测模型经过了彻底的评估,展示了稳健的多变量分类性能。五个关键的咖啡属性,苦涩,酸度,身体,强度,使用GC-HRMS数据成功预测了焙烧水平。结果显示,所有模型的预测准确性都很高,范围从88.9%(苦味)到94.4%(焙烧水平)。这项研究代表了咖啡质量控制自动化方法的重大进展,与现有文献相比,模型的预测能力显著提高。
    This paper presents a study that assesses the application of chemometrics for classifying coffee samples in a quality control context. High-resolution and accurate mass measurements were utilized as input for pixel-based orthogonal partial least squares discriminant analysis (OPLS-DA) models. The compositional data were acquired through a fully automated workflow combining headspace solid-phase microextraction and gas chromatography-high-resolution mass spectrometry (GC-HRMS) using an FT-Orbitrap® mass analyzer. A workflow centered on accurate mass measurements was successfully utilized for group-type analysis, offering an alternative to methods relying solely on MS similarity searches. The predictive models underwent thorough evaluation, demonstrating robust multivariate classification performance. Five key coffee attributes, bitterness, acidity, body, intensity, and roasting level were successfully predicted using GC-HRMS data. The results revealed strong predictive accuracy across all models, ranging from 88.9 % (bitterness) to 94.4 % (roasting level). This study represents a significant advancement in automating methods for coffee quality control, notably increasing the predictive ability of the models compared to existing literature.
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