Statistical model

统计模型
  • 文章类型: Journal Article
    生物医学物理数据在促进我们对人类健康的理解方面的关键作用强调了它的重要性。解开疾病的潜在机制,并促进创新医疗和干预措施的发展。这些数据是一种基本资源,赋予研究人员权力,医疗保健专业人员,和科学家做出明智的决定,先锋研究,并最终提高全球医疗保健质量和个人福祉。它是不断追求医疗进步和改善医疗保健结果的基石。本文旨在解决当应用于从初始故障发生中删失的渐进生物医学数据时,估计与修改的Weibull分布相关的未知参数和可靠性度量方面的挑战。在这种情况下,本文提出了经典和贝叶斯技术来推导未知参数的估计,生存,和故障率函数。贝叶斯估计是在考虑非对称和对称损失函数的情况下计算的。采用马尔可夫链蒙特卡罗方法来获得这些贝叶斯估计及其相应的最高后验密度可信区间。由于这些估计器固有的复杂性,这在理论上是无法比较的,进行了一项模拟研究,以评估各种估计程序的性能。此外,一系列的优化标准被用来确定最有效的渐进控制策略。最后,本文介绍了一个医学应用来说明所提出的估计量的有效性。数值结果表明,贝叶斯估计通过实现最小的均方根误差和更窄的间隔长度而优于其他估计方法。
    The importance of biomedical physical data is underscored by its crucial role in advancing our comprehension of human health, unraveling the mechanisms underlying diseases, and facilitating the development of innovative medical treatments and interventions. This data serves as a fundamental resource, empowering researchers, healthcare professionals, and scientists to make informed decisions, pioneer research, and ultimately enhance global healthcare quality and individual well-being. It forms a cornerstone in the ongoing pursuit of medical progress and improved healthcare outcomes. This article aims to tackle challenges in estimating unknown parameters and reliability measures related to the modified Weibull distribution when applied to censored progressive biomedical data from the initial failure occurrence. In this context, the article proposes both classical and Bayesian techniques to derive estimates for unknown parameters, survival, and failure rate functions. Bayesian estimates are computed considering both asymmetric and symmetric loss functions. The Markov chain Monte Carlo method is employed to obtain these Bayesian estimates and their corresponding highest posterior density credible intervals. Due to the inherent complexity of these estimators, which cannot be theoretically compared, a simulation study is conducted to evaluate the performance of various estimation procedures. Additionally, a range of optimization criteria is utilized to identify the most effective progressive control strategies. Lastly, the article presents a medical application to illustrate the effectiveness of the proposed estimators. Numerical findings indicate that Bayesian estimates outperform other estimation methods by achieving minimal root mean square errors and narrower interval lengths.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Editorial
    暂无摘要。
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    在生存和随机寿命建模中,许多家庭的分布有时被认为是不自然的,理论上不合理,有时是多余的。这里,使用Bilal分布(BD)和Kavya-Manoharan(KM)简约转化家族开发了一种新颖的简约生存模型。除了其他分析属性,分析了概率密度函数(PDF)的形式和危险率分布的行为。这些见解既是理论的,也是实践的。理论上,我们提供了来自Kavya-ManoharanBilal分布的阶次统计量的单矩和乘积矩的显式方程。实际上,最大似然(ML)技术,它基于简单随机抽样(SRS)和排序集抽样(RSS)样本方案,用于估计参数。数值模拟被用作比较各种采样技术的主要方法。
    In survival and stochastic lifespan modeling, numerous families of distributions are sometimes considered unnatural, unjustifiable theoretically, and occasionally superfluous. Here, a novel parsimonious survival model is developed using the Bilal distribution (BD) and the Kavya-Manoharan (KM) parsimonious transformation family. In addition to other analytical properties, the forms of probability density function (PDF) and behavior of the distributions\' hazard rates are analyzed. The insights are theoretical as well as practical. Theoretically, we offer explicit equations for the single and product moments of order statistics from Kavya-Manoharan Bilal Distribution. Practically, maximum likelihood (ML) technique, which is based on simple random sampling (SRS) and ranked set sampling (RSS) sample schemes, is employed to estimate the parameters. Numerical simulations are used as the primary methodology to compare the various sampling techniques.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    在我们以前的工作中建立了植物黄酮对革兰氏阳性菌的抗菌定量结构-活性关系,细胞膜被证实是主要的作用部位。为了研究植物类黄酮对革兰氏阴性菌和革兰氏阳性菌是否具有相似的抗菌作用和机制,在这里,使用微量稀释液法测定了37种植物黄酮对大肠杆菌的最低抑菌浓度(MIC),然后分析其亲脂参数ACD/LogP或LogD7.40值与MIC之间的相关性。同时,还分析了ACD/LogP或LogD7.40值与文献报道的46种植物类黄酮对大肠杆菌的MIC之间的相关性。两组结果表明,LogP值与植物黄酮对革兰氏阴性菌的MIC之间存在显着相关性。然而,从其亲脂性参数很难有效预测植物黄酮对革兰氏阴性菌的MIC。通过比较植物黄酮对革兰氏阴性菌和革兰氏阳性菌的两个回归曲线,进一步发现,当它们的LogP值小于约3.0时,大多数植物类黄酮对革兰氏阴性菌的抗菌活性强于对革兰氏阳性菌的抗菌活性,但当它们的LogP值大于约3.6时,则相反。此外,这种比较还表明,与主要作用于革兰氏阳性细菌的细胞膜不同,植物类黄酮对革兰氏阴性物种有多种机制,而细胞膜也是其中的重要作用部位。结合已报道的黄酮类化合物的酶抑制活性与LogP值的相关性分析,进一步表明,DNA促旋酶是植物类黄酮抗革兰氏阴性菌的另一个重要靶标。
    The antimicrobial quantitative structure-activity relationship of plant flavonoids against Gram-positive bacteria was established in our previous works, and the cell membrane was confirmed as a major site of action. To investigate whether plant flavonoids have similar antibacterial effects and mechanisms against both Gram-negative and Gram-positive bacteria, here, the minimum inhibitory concentrations (MICs) of 37 plant flavonoids against Escherichia coli were determined using the microdilution broth method, and then the correlation between their lipophilic parameter ACD/LogP or LogD7.40 value and their MIC was analyzed. Simultaneously, the correlation between the ACD/LogP or LogD7.40 value and the MIC of 46 plant flavonoids reported in the literature against E. coli was also analyzed. Both sets of results showed that there is a significant correlation between the LogP value and the MIC of plant flavonoids against Gram-negative bacteria. However, it is difficult to effectively predict the MIC of plant flavonoids against Gram-negative bacteria from their lipophilic parameters. By comparing two regression curves derived from plant flavonoids against Gram-negative and Gram-positive bacteria, it was further discovered that the antibacterial activities of most plant flavonoids against Gram-negative bacteria are stronger than those against Gram-positive bacteria when their LogP values are less than approximately 3.0, but the opposite is true when their LogP values are more than approximately 3.6. Moreover, this comparison also suggests that unlike mainly acting on the cell membrane of Gram-positive bacteria, plant flavonoids have multiple mechanisms against Gram-negative species, while the cell membrane is also an important action site among them. Combined with the correlation analyses between the enzyme inhibitory activity and the LogP value of the reported flavonoids, it was further suggested that DNA gyrase is another important target of plant flavonoids against Gram-negative bacteria.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    气候,天气和环境变化对传染病的传播模式产生了重大影响,有必要开发预警系统,以预测潜在影响并及时有效地做出反应。统计建模在理解气候因素与传染病传播之间的复杂关系中起着关键作用。例如,时间序列回归模型和空间聚类分析已被用来识别危险因素并预测传染病的时空模式。最近先进的时空模型和机器学习为不确定性建模提供了一个越来越强大的框架。由于数据的动态性和多面性,这在气候驱动的疾病监测中至关重要。此外,人工智能(AI)技术,包括深度学习和神经网络,擅长捕捉气候和环境数据集中复杂的模式和隐藏的关系。基于网络的数据已经成为包括气候变量和疾病发生的其他数据集的有力补充。然而,考虑到气候-疾病相互作用的复杂性和非线性,需要先进的技术来整合和分析这些不同的数据,以获得对即将爆发的更准确的预测,流行病或大流行病。本文概述了创建气候驱动的预警系统的方法,重点是统计模型的适用性和选择,以及利用时空和机器学习技术的建议。通过解决局限性并接受未来研究的建议,我们可以加强准备和应对策略,最终有助于在不断变化的气候挑战面前保障公众健康。
    Climate, weather and environmental change have significantly influenced patterns of infectious disease transmission, necessitating the development of early warning systems to anticipate potential impacts and respond in a timely and effective way. Statistical modelling plays a pivotal role in understanding the intricate relationships between climatic factors and infectious disease transmission. For example, time series regression modelling and spatial cluster analysis have been employed to identify risk factors and predict spatial and temporal patterns of infectious diseases. Recently advanced spatio-temporal models and machine learning offer an increasingly robust framework for modelling uncertainty, which is essential in climate-driven disease surveillance due to the dynamic and multifaceted nature of the data. Moreover, Artificial Intelligence (AI) techniques, including deep learning and neural networks, excel in capturing intricate patterns and hidden relationships within climate and environmental data sets. Web-based data has emerged as a powerful complement to other datasets encompassing climate variables and disease occurrences. However, given the complexity and non-linearity of climate-disease interactions, advanced techniques are required to integrate and analyse these diverse data to obtain more accurate predictions of impending outbreaks, epidemics or pandemics. This article presents an overview of an approach to creating climate-driven early warning systems with a focus on statistical model suitability and selection, along with recommendations for utilizing spatio-temporal and machine learning techniques. By addressing the limitations and embracing the recommendations for future research, we could enhance preparedness and response strategies, ultimately contributing to the safeguarding of public health in the face of evolving climate challenges.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    单细胞成簇的规则间隔的短回文重复序列测序(scCRISPR-seq)是一种新兴的高通量CRISPR筛选技术,其中对扰动的真正细胞反应与不同细胞簇之间的指导RNA(gRNA)的感染比例偏差有关。这些效应的混合将噪声引入scCRISPR-seq数据分析中,从而阻碍了相关研究。我们开发了scDecouple,以将扰动的真实细胞反应与受感染比例偏差的影响分离。scDecouple首先对扰动细胞中基因表达谱的分布进行建模,然后迭代地找到细胞簇比例的最大可能性以及每个gRNA的细胞反应。我们在一系列模拟实验中证明了它的性能。通过将scDecouple应用于真实的scCRISPR-seq数据,我们发现scDecouple增强了生物扰动相关基因的识别。scDecouple可以有益于scCRISPR-seq数据分析,特别是在异质样品或复杂gRNA文库的情况下。
    Single-cell clustered regularly interspaced short palindromic repeats-sequencing (scCRISPR-seq) is an emerging high-throughput CRISPR screening technology where the true cellular response to perturbation is coupled with infected proportion bias of guide RNAs (gRNAs) across different cell clusters. The mixing of these effects introduces noise into scCRISPR-seq data analysis and thus obstacles to relevant studies. We developed scDecouple to decouple true cellular response of perturbation from the influence of infected proportion bias. scDecouple first models the distribution of gene expression profiles in perturbed cells and then iteratively finds the maximum likelihood of cell cluster proportions as well as the cellular response for each gRNA. We demonstrated its performance in a series of simulation experiments. By applying scDecouple to real scCRISPR-seq data, we found that scDecouple enhances the identification of biologically perturbation-related genes. scDecouple can benefit scCRISPR-seq data analysis, especially in the case of heterogeneous samples or complex gRNA libraries.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • 文章类型: Journal Article
    数字编码超表面是连接数字空间和电磁波空间的平台,因此,由于其在重塑无线信道和实现新的通信架构方面的有趣价值,因此获得了很多关注。相应地,迫切需要电磁信息理论来揭示通信容量的上限,并支持基于超表面的通信系统的准确设计。为此,我们提出了数字编码超表面的宏观模型和统计模型。宏观模型均匀地适应元原子的数字和电磁方面,并且基于少量的模拟或测量来预测数字编码元表面的所有可能的散射场。全波模拟和实验结果表明,该宏观模型是可行和准确的。进一步提出了一种统计模型,用于将元原子之间的互耦与协方差相关联,并计算数字编码超表面的等效电流的熵。这两种模型可以帮助可重构智能表面实现更准确的波束形成和信道估计,从而提高信号功率和覆盖范围。此外,这些模型将鼓励在基于超表面的直接数字调制系统中创建预编码码本,目的是接近信道容量的上限。有了这两种模型,当前空间和当前熵的概念,以及从编码空间到波空间的信息损失分析,是第一次建立,帮助弥合数字世界和物理世界之间的差距,推进电磁信息理论和新架构无线系统的发展。
    A digital coding metasurface is a platform connecting the digital space and electromagnetic wave space, and has therefore gained much attention due to its intriguing value in reshaping wireless channels and realizing new communication architectures. Correspondingly, there is an urgent need for electromagnetic information theory that reveals the upper limit of communication capacity and supports the accurate design of metasurface-based communication systems. To this end, we propose a macroscopic model and a statistical model of the digital coding metasurface. The macroscopic model uniformly accommodates both digital and electromagnetic aspects of the meta-atoms and predicts all possible scattered fields of the digital coding metasurface based on a small number of simulations or measurements. Full-wave simulations and experimental results show that the macroscopic model is feasible and accurate. A statistical model is further proposed to correlate the mutual coupling between meta-atoms with covariance and to calculate the entropy of the equivalent currents of digital coding metasurface. These two models can help reconfigurable intelligent surfaces achieve more accurate beamforming and channel estimation, and thus improve signal power and coverage. Moreover, the models will encourage the creation of a precoding codebook in metasurface-based direct digital modulation systems, with the aim of approaching the upper limit of channel capacity. With these two models, the concepts of current space and current entropy, as well as the analysis of information loss from the coding space to wave space, is established for the first time, helping to bridge the gap between the digital world and the physical world, and advancing developments of electromagnetic information theory and new-architecture wireless systems.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

       PDF(Pubmed)

  • Age estimation based on tissues or body fluids is an important task in forensic science. The changes of DNA methylation status with age have certain rules, which can be used to estimate the age of the individuals. Therefore, it is of great significance to discover specific DNA methylation sites and develop new age estimation models. At present, statistical models for age estimation have been developed based on the rule that DNA methylation status changes with age. The commonly used models include multiple linear regression model, multiple quantile regression model, support vector machine model, artificial neural network model, random forest model, etc. In addition, there are many factors that affect the level of DNA methylation, such as the tissue specificity of methylation. This paper reviews these modeling methods and influencing factors for age estimation based on DNA methylation, with a view to provide reference for the establishment of age estimation models.
    基于人体组织或体液进行年龄推断是法庭科学的一项重要任务。DNA甲基化状态随年龄变化具有一定的规律,可用于推断个体年龄,因此,发现特定的DNA甲基化位点并开发新的年龄推断模型具有重要意义。目前已有研究利用DNA甲基化状态随年龄发生变化的规律开发出用于推断年龄的统计模型,较常使用的有多元线性回归模型、多元分位数回归模型、支持向量机模型、人工神经网络模型和随机森林模型等。此外,影响DNA甲基化水平的因素较多,如甲基化的组织特异性。本文拟对这些基于DNA甲基化推断年龄的建模方法及影响因素进行综述,以期为建立年龄推断模型提供参考。.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    背景:胆囊腺瘤是胆囊癌的癌前病变。然而,在手术前将其与胆囊的胆固醇息肉区分开来是具有挑战性的。因此,我们旨在全面探讨导致胆囊腺瘤形成的各种危险因素,以促进临床医生的知情诊断和治疗。
    方法:我们对2015年1月至2022年12月在青岛大学附属医院行胆囊切除术的患者进行了回顾性分析。术后病理检查后,患者被分为胆固醇息肉组和腺瘤组.我们分析了它们的基线特征,超声成像变量,和使用logistic的生化数据,套索,和逐步回归。随后,我们构建了基于独立危险因素的术前预测模型。
    结果:模型组520例胆囊息肉和288例胆囊腺瘤的回归分析显示,年龄,胆囊壁厚,息肉大小,回声,花梗,腺苷脱氨酶(ADA)水平是胆囊腺瘤的独立预测因子,均P<0.05。使用这些指标,我们建立了一个回归方程:Logistic(P)=-5.615+0.018*年龄-4.64*胆囊壁厚度+1.811*息肉大小+2.855*息肉回声+0.97*计算+0.092*ADA。所得曲线下面积(AUC)值为0.894(95%CI:0.872-0.917,P<0.01),灵敏度为89.20%,特异性为79.40%,腺瘤检测的总体准确率为84.41%。
    结论:年龄,息肉大小,胆囊壁厚,息肉回声,花梗,和ADA水平是胆囊腺瘤的独立危险因素。
    BACKGROUND: Gallbladder adenoma represents a precancerous lesion of gallbladder cancer. However, distinguishing it from cholesteryl polyps of the gallbladder before surgery is challenging. Thus, we aimed to comprehensively explore various risk factors contributing to the formation of gallbladder adenoma to facilitate an informed diagnosis and treatment by clinicians.
    METHODS: We conducted a retrospective analysis of patients who had undergone cholecystectomy at the Affiliated Hospital of Qingdao University between January 2015 and December 2022. Following postoperative pathological examination, patients were categorized into cholesterol polyp and adenoma groups. We analyzed their baseline characteristics, ultrasound imaging variables, and biochemical data using logistic, lasso, and stepwise regression. Subsequently, we constructed a preoperative prediction model based on the independent risk factors.
    RESULTS: Regression analysis of 520 gallbladder polyps and 288 gallbladder adenomas in the model group revealed that age, gallbladder wall thickness, polyp size, echogenicity, pedunculation, and adenosine deaminase (ADA) levels were independent predictors of gallbladder adenoma, all with P < 0.05. Using these indicators, we established a regression equation: Logistic (P) = -5.615 + 0.018 ∗ age - 4.64 ∗ gallbladder wall thickness + 1.811 ∗ polyp size + 2.855 ∗ polyp echo + 0.97∗ pedunculation + 0.092 ∗ ADA. The resulting area under the curve (AUC) value was 0.894 (95 % CI: 0.872-0.917, P < 0.01), with a sensitivity of 89.20 %, specificity of 79.40 %, and overall accuracy of 84.41 % for adenoma detection.
    CONCLUSIONS: Age, polyp size, gallbladder wall thickness, polyp echogenicity, pedunculation, and ADA levels emerge as independent risk factors for gallbladder adenoma.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

  • 文章类型: Journal Article
    了解河道形态的变化如何影响河岸植被与河流流量之间的关系,对于干旱环境中的科学河流治理至关重要。但缺乏相关的定量研究。为了量化通道平面复杂度的影响,渠道形式最活跃的方面之一,关于年尺度和流域尺度的河岸植被-流量关系,对黑河下游的两条河流进行了比较研究,中国。有关河岸植被和河道形态的信息来自多源遥感图像和哥白尼数字高程模型,并从现场观测中获得了河流流量和地下水位数据。河道平面复杂度计算为河流所有河道的总长度与河流两端之间的直线距离之比。通过多元线性模型对河岸植被-流量关系进行量化,该模型将零流量条件下的河岸植被退化与河流流量改善相结合。在2002-2020年期间,(1)就平面复杂性和剖面坡度而言,一条河流是另一条河流的1.5和1.04倍,分别;(2)一条河流的水年径流量为3.2×108至7.6×108m3,另一条河流的水年径流量为0.8×108至4.8×108m3;(3)两条河流的河岸植被状况指标分别为2202-4113和1242-3362;(4)较复杂的河流在改善河岸植被方面的流量效率是另一条的2.3倍。结果表明,平面复杂性与流动效率呈正相关,根本原因是地下水补给率的变化,效率的变化可能大于平面复杂性本身的变化。河道形式对河岸植被-流量关系的影响的时空变化值得进一步研究和关注。
    Understanding how changes in channel form affect the relationships between riparian vegetation and river flow is critical to scientific river regulation in arid environments, but relevant quantitative research is lacking. Aiming to quantify the effect of channel planar complexity, one of the most dynamic aspects of channel form, on riparian vegetation-flow relationships at annual and basin scales, a comparative study was conducted on two rivers in the lower Heihe River, China. Information on riparian vegetation and channel form was derived from multi-source remote sensing imagery and the Copernicus digital elevation model, and river flow and groundwater table data were obtained from field observations. Channel planar complexity was calculated as the ratio of the total length of all channels of a river to the straight-line distance between the two ends of the river, and the riparian vegetation-flow relationship was quantified by a multiple linear model that couples riparian vegetation degradation under zero-flow condition and riparian vegetation improvement by river flow. During 2002-2020, (1) one river was 1.5 and 1.04 times the other in terms of planar complexity and profile slope, respectively; (2) the water-year runoff of one river was 3.2 × 108 to 7.6 × 108 m3 and that of the other river was 0.8 × 108 to 4.8 × 108 m3; (3) the riparian vegetation condition indicator of the two rivers was 2202-4113 and 1242-3362, respectively; (4) the more complex river was 2.3 times the other in the efficiency of flow in improving riparian vegetation. The results indicate that planar complexity is positively correlated with flow\'s efficiency, with the underlying cause being changes in groundwater recharge rates, and that the change in efficiency can be greater than the change in planar complexity itself. The spatio-temporal variability in the effect of channel form on riparian vegetation-flow relationships merits further investigation and serious attention in river regulation.
    导出

    更多引用

    收藏

    翻译标题摘要

    我要上传

    求助全文

公众号