Ensemble learning

合奏学习
  • 文章类型: Journal Article
    胃癌根治术后并发症严重影响术后恢复,需要准确预测风险。因此,本研究旨在开发一种预测模型,用于指导胃癌患者围手术期并发症的临床决策.回顾性分析2022年4月至2023年6月在南京医科大学第一附属医院行胃癌根治术的患者。共纳入166例患者。患者人口学特征,实验室检查结果,并记录手术病理特征。术前腹部CT扫描通过3Dslicer对患者的内脏脂肪区域进行分割,采用3D卷积神经网络(3D-CNN)提取图像特征,并采用LASSO回归模型进行特征选择。此外,采用集成学习策略训练胃癌的特征并预测术后并发症。LGBM(光梯度升压机)的预测性能,XGB(XGBoost),RF(随机森林),通过五次交叉验证对GBDT(梯度提升决策树)模型进行了评估。本研究成功构建了基于优化算法的胃癌根治术后早期并发症预测模型,LGBM.LGBM模型的AUC值为0.9232,准确率为87.28%(95%CI,75.61-98.95%),超越其他型号的性能。通过对围手术期临床数据和内脏脂肪影像组学的集成学习和整合,建立了预测LGBM模型。该模型有可能促进胃癌术后患者的个体化临床决策和早期康复。
    Postoperative complications of radical gastrectomy seriously affect postoperative recovery and require accurate risk prediction. Therefore, this study aimed to develop a prediction model specifically tailored to guide perioperative clinical decision-making for postoperative complications in patients with gastric cancer. A retrospective analysis was conducted on patients who underwent radical gastrectomy at the First Affiliated Hospital of Nanjing Medical University between April 2022 and June 2023. A total of 166 patients were enrolled. Patient demographic characteristics, laboratory examination results, and surgical pathological features were recorded. Preoperative abdominal CT scans were used to segment the visceral fat region of the patients through 3Dslicer, a 3D Convolutional Neural Network (3D-CNN) to extract image features and the LASSO regression model was employed for feature selection. Moreover, an ensemble learning strategy was adopted to train the features and predict postoperative complications of gastric cancer. The prediction performance of the LGBM (Light Gradient Boosting Machine), XGB (XGBoost), RF (Random Forest), and GBDT (Gradient Boosting Decision Tree) models was evaluated through fivefold cross-validation. This study successfully constructed a model for predicting early complications following radical gastrectomy based on the optimal algorithm, LGBM. The LGBM model yielded an AUC value of 0.9232 and an accuracy of 87.28% (95% CI, 75.61-98.95%), surpassing the performance of other models. Through ensemble learning and integration of perioperative clinical data and visceral fat radiomics, a predictive LGBM model was established. This model has the potential to facilitate individualized clinical decision-making and the early recovery of patients with gastric cancer post-surgery.
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  • 文章类型: Journal Article
    背景:诊断错误会带来重大的健康风险,并导致患者死亡。随着电子健康记录的日益普及,机器学习模型为提高诊断质量提供了一条有前途的途径。目前的研究主要集中在一组有限的疾病和充足的训练数据,忽略数据可用性有限的诊断方案。
    目的:本研究旨在开发一种基于信息检索(IR)的框架,该框架可容纳数据稀疏性,以促进更广泛的诊断决策支持。
    方法:我们介绍了一个基于IR的诊断决策支持框架,称为CliniqIR。它使用临床文本记录,统一的医学语言系统词库,和3300万份PubMed摘要,以独立于训练数据可用性对广泛的诊断进行分类。CliniqIR旨在与任何IR框架兼容。因此,我们使用密集和稀疏检索方法实现了它。我们将CliniqIR的性能与预训练的临床变压器模型的性能进行了比较,例如在监督和零射设置下来自变压器的临床双向编码器表示(ClinicalBERT)。随后,我们结合了监督微调ClinicalBERT和CliniqIR的优势,构建了一个集成框架,提供最先进的诊断预测.
    结果:在没有任何训练数据的复杂诊断数据集(DC3)上,CliniqIR模型在其前3个预测中返回了正确的诊断。关于重症监护医学信息集市III数据集,CliniqIR模型在预测<5个训练样本的诊断方面超过ClinicalBERT,平均倒数排名差异为0.10。在零射击环境中,模型没有接受疾病特异性训练,CliniqIR仍然优于预训练的变压器模型,其平均倒数排名至少为0.10。此外,在大多数情况下,我们的集成框架超越了其各个组件的性能,证明其增强了做出精确诊断预测的能力。
    结论:我们的实验强调了IR在利用非结构化知识资源识别不常遇到的诊断方面的重要性。此外,我们的集成框架受益于结合监督和基于检索的模型的互补优势来诊断广泛的疾病.
    BACKGROUND: Diagnostic errors pose significant health risks and contribute to patient mortality. With the growing accessibility of electronic health records, machine learning models offer a promising avenue for enhancing diagnosis quality. Current research has primarily focused on a limited set of diseases with ample training data, neglecting diagnostic scenarios with limited data availability.
    OBJECTIVE: This study aims to develop an information retrieval (IR)-based framework that accommodates data sparsity to facilitate broader diagnostic decision support.
    METHODS: We introduced an IR-based diagnostic decision support framework called CliniqIR. It uses clinical text records, the Unified Medical Language System Metathesaurus, and 33 million PubMed abstracts to classify a broad spectrum of diagnoses independent of training data availability. CliniqIR is designed to be compatible with any IR framework. Therefore, we implemented it using both dense and sparse retrieval approaches. We compared CliniqIR\'s performance to that of pretrained clinical transformer models such as Clinical Bidirectional Encoder Representations from Transformers (ClinicalBERT) in supervised and zero-shot settings. Subsequently, we combined the strength of supervised fine-tuned ClinicalBERT and CliniqIR to build an ensemble framework that delivers state-of-the-art diagnostic predictions.
    RESULTS: On a complex diagnosis data set (DC3) without any training data, CliniqIR models returned the correct diagnosis within their top 3 predictions. On the Medical Information Mart for Intensive Care III data set, CliniqIR models surpassed ClinicalBERT in predicting diagnoses with <5 training samples by an average difference in mean reciprocal rank of 0.10. In a zero-shot setting where models received no disease-specific training, CliniqIR still outperformed the pretrained transformer models with a greater mean reciprocal rank of at least 0.10. Furthermore, in most conditions, our ensemble framework surpassed the performance of its individual components, demonstrating its enhanced ability to make precise diagnostic predictions.
    CONCLUSIONS: Our experiments highlight the importance of IR in leveraging unstructured knowledge resources to identify infrequently encountered diagnoses. In addition, our ensemble framework benefits from combining the complementary strengths of the supervised and retrieval-based models to diagnose a broad spectrum of diseases.
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  • 文章类型: Journal Article
    背景:由于多重耐药生物体(MDROs)引起的医疗保健相关感染,如耐甲氧西林金黄色葡萄球菌(MRSA)和艰难梭菌(CDI),给我们的医疗基础设施带来沉重负担。
    目的:MDROs的筛查是防止传播的重要机制,但却是资源密集型的。这项研究的目的是开发可以使用电子健康记录(EHR)数据预测定植或感染风险的自动化工具,提供有用的信息来帮助感染控制,并指导经验性抗生素覆盖。
    方法:我们回顾性地开发了一个机器学习模型来检测在弗吉尼亚大学医院住院患者样本采集时未分化患者的MRSA定植和感染。我们使用来自患者EHR数据的入院和住院期间信息的临床和非临床特征来构建模型。此外,我们在EHR数据中使用了一类从联系网络派生的特征;这些网络特征可以捕获患者与提供者和其他患者的联系,提高预测MRSA监测试验结果的模型可解释性和准确性。最后,我们探索了不同患者亚群的异质模型,例如,入住重症监护病房或急诊科的人或有特定检测史的人,哪个表现更好。
    结果:我们发现惩罚逻辑回归比其他方法表现更好,当我们使用多项式(二次)变换特征时,该模型的性能根据其接收器操作特征-曲线下面积得分提高了近11%。预测MDRO风险的一些重要特征包括抗生素使用,手术,使用设备,透析,患者的合并症状况,和网络特征。其中,网络功能增加了最大的价值,并将模型的性能提高了至少15%。对于特定患者亚群,具有相同特征转换的惩罚逻辑回归模型也比其他模型表现更好。
    结论:我们的研究表明,使用来自EHR数据的临床和非临床特征,通过机器学习方法可以非常有效地进行MRSA风险预测。网络特征是最具预测性的,并且提供优于现有方法的显著改进。此外,不同患者亚群的异质预测模型提高了模型的性能。
    BACKGROUND: Health care-associated infections due to multidrug-resistant organisms (MDROs), such as methicillin-resistant Staphylococcus aureus (MRSA) and Clostridioides difficile (CDI), place a significant burden on our health care infrastructure.
    OBJECTIVE: Screening for MDROs is an important mechanism for preventing spread but is resource intensive. The objective of this study was to develop automated tools that can predict colonization or infection risk using electronic health record (EHR) data, provide useful information to aid infection control, and guide empiric antibiotic coverage.
    METHODS: We retrospectively developed a machine learning model to detect MRSA colonization and infection in undifferentiated patients at the time of sample collection from hospitalized patients at the University of Virginia Hospital. We used clinical and nonclinical features derived from on-admission and throughout-stay information from the patient\'s EHR data to build the model. In addition, we used a class of features derived from contact networks in EHR data; these network features can capture patients\' contacts with providers and other patients, improving model interpretability and accuracy for predicting the outcome of surveillance tests for MRSA. Finally, we explored heterogeneous models for different patient subpopulations, for example, those admitted to an intensive care unit or emergency department or those with specific testing histories, which perform better.
    RESULTS: We found that the penalized logistic regression performs better than other methods, and this model\'s performance measured in terms of its receiver operating characteristics-area under the curve score improves by nearly 11% when we use polynomial (second-degree) transformation of the features. Some significant features in predicting MDRO risk include antibiotic use, surgery, use of devices, dialysis, patient\'s comorbidity conditions, and network features. Among these, network features add the most value and improve the model\'s performance by at least 15%. The penalized logistic regression model with the same transformation of features also performs better than other models for specific patient subpopulations.
    CONCLUSIONS: Our study shows that MRSA risk prediction can be conducted quite effectively by machine learning methods using clinical and nonclinical features derived from EHR data. Network features are the most predictive and provide significant improvement over prior methods. Furthermore, heterogeneous prediction models for different patient subpopulations enhance the model\'s performance.
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  • 文章类型: Journal Article
    排尿膀胱尿道造影(VCUG)是诊断和分级膀胱输尿管反流(VUR)的金标准。然而,来自排尿膀胱尿道图的VUR分级是高度主观的,可靠性低。这项研究旨在开发一种深度学习模型,以提高VCUG上VUR分级的可靠性,并将其性能与临床医生的性能进行比较。
    在这项中国的回顾性研究中,VCUG图像是在2019年1月至2022年9月期间从我们的机构收集的,作为用于训练的内部数据集,以及4个外部数据集作为用于验证的外部测试集。样本分为训练集(N=1000)和验证集(N=500),内部测试集(N=168),和外部测试集(N=280)。基于集成学习的模型,深VCUG,使用Res-Net101和投票方法来预测VUR等级。使用热图评估了分级性能,接收器工作特性曲线下面积(AUC),灵敏度,特异性,准确度,内部和外部测试集中的F1分数。在外部测试集中探索了有和没有Deep-VCUG辅助预测VUR等级的四名临床医生(2名儿科泌尿科医师和2名放射科医师)的表现。
    总共收集了1948张VCUG图像(内部数据集=1668;多中心外部数据集=280)。为了评估单边VUR分级,深度VCUG在内部和外部测试集中实现了0.962(95%置信区间[CI]:0.943-0.978)和0.944(95%[CI]:0.921-0.964)的AUC,分别,对于双边VUR分级,Deep-VCUG还实现了0.960(95%[CI]:0.922-0.983)和0.924(95%[CI]:0.887-0.957)的高AUC。使用投票方法的Deep-VCUG模型在基于VCUG图像的分类方面优于单个模型和临床医生。此外,在Dee-VCUG的协助下,初级和高级临床医生的分类能力明显提高。
    Deep-VCUG模型是一个可推广的模型,目标,和基于VCUG成像的膀胱输尿管反流分级的准确工具,并对临床医生对VUR分级适用性有很好的帮助。
    本研究得到了中国自然科学基金的资助,上海医学院“福清学者”学生科研计划,复旦大学,大湾区精准医学研究院(广州)项目。
    UNASSIGNED: Voiding cystourethrography (VCUG) is the gold standard for the diagnosis and grading of vesicoureteral reflux (VUR). However, VUR grading from voiding cystourethrograms is highly subjective with low reliability. This study aimed to develop a deep learning model to improve reliability for VUR grading on VCUG and compare its performance to that of clinicians.
    UNASSIGNED: In this retrospective study in China, VCUG images were collected between January 2019 and September 2022 from our institution as an internal dataset for training and 4 external data sets as external testing set for validation. Samples were divided into training (N = 1000) and validation sets (N = 500), internal testing set (N = 168), and external testing set (N = 280). An ensemble learning-based model, Deep-VCUG, using Res-Net 101 and the voting methods was developed to predict VUR grade. The grading performance was assessed using heatmaps, area under the receiver operating characteristic curve (AUC), sensitivity, specificity, accuracy, and F1 score in the internal and external testing set. The performances of four clinicians (2 pediatric urologists and 2 radiologists) with and without the Deep-VCUG assisted to predict VUR grade were explored in external testing sets.
    UNASSIGNED: A total of 1948 VCUG images were collected (Internal dataset = 1668; multi-center external dataset = 280). For assessing unilateral VUR grading, the Deep-VCUG achieved AUCs of 0.962 (95% confidence interval [CI]: 0.943-0.978) and 0.944 (95% [CI]: 0.921-0.964) in the internal and external testing sets, respectively, for bilateral VUR grading, the Deep-VCUG also achieved high AUCs of 0.960 (95% [CI]: 0.922-0.983) and 0.924 (95% [CI]: 0.887-0.957). The Deep-VCUG model using voting method outperformed single model and clinician in terms of classification based on VCUG image. Moreover, Under the Dee-VCUG assisted, the classification ability of junior and senior clinicians was significantly improved.
    UNASSIGNED: The Deep-VCUG model is a generalizable, objective, and accurate tool for vesicoureteral reflux grading based on VCUG imaging and had good assistance with clinicians to VUR grading applicability.
    UNASSIGNED: This study was supported by Natural Science Foundation of China, \"Fuqing Scholar\" Student Scientific Research Program of Shanghai Medical College, Fudan University, and the Program of Greater Bay Area Institute of Precision Medicine (Guangzhou).
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  • 文章类型: Journal Article
    肠道微生物组的改变与阿尔茨海默病(AD)的发病机制有关,可用作诊断措施。然而,肠道微生物组的纵向数据及其对AD发生和进展的预后意义的认识有限.本研究的目的是开发基于肠道微生物组数据的AD发展的可靠预测模型。在这项纵向研究中,我们调查了49名轻度认知障碍(MCI)患者的肠道微生物组,平均(SD)随访3.7(0.6)年,使用猎枪宏基因组学。在4年随访(4yFU)结束时,27名MCI患者转化为AD痴呆,22名MCI患者保持稳定。从稳定的MCI患者中区分AD痴呆转化者的最佳分类模型包括24属,在BL处产生0.87的接受者工作特征曲线下面积(AUROC),1yFU为0.92,4yFU为0.95。通过分析25个GO(基因本体论)特征获得了具有功能数据的最佳模型,在BL时AUROC为0.87,1yFU时为0.85,4yFU时为0.81,33KO[京都基因和基因组百科全书(KEGG)直系同源]特征,BL时AUROC为0.79,1yFU为0.88,4yFU为0.82。对这三个模型使用集成学习,包括具有四个年龄参数的临床模型,性别,体重指数(BMI)和载脂蛋白E(ApoE)基因型,在BL时产生0.96的AUROC,1yFU为0.96,4yFU为0.97。总之,我们确定了新颖且及时稳定的肠道微生物组算法,该算法可准确预测MCI患者在4yFU期间进展为AD痴呆.
    Alterations in the gut microbiome are associated with the pathogenesis of Alzheimer\'s disease (AD) and can be used as a diagnostic measure. However, longitudinal data of the gut microbiome and knowledge about its prognostic significance for the development and progression of AD are limited. The aim of the present study was to develop a reliable predictive model based on gut microbiome data for AD development. In this longitudinal study, we investigated the intestinal microbiome in 49 mild cognitive impairment (MCI) patients over a mean (SD) follow-up of 3.7 (0.6) years, using shotgun metagenomics. At the end of the 4-year follow-up (4yFU), 27 MCI patients converted to AD dementia and 22 MCI patients remained stable. The best taxonomic model for the discrimination of AD dementia converters from stable MCI patients included 24 genera, yielding an area under the receiver operating characteristic curve (AUROC) of 0.87 at BL, 0.92 at 1yFU and 0.95 at 4yFU. The best models with functional data were obtained via analyzing 25 GO (Gene Ontology) features with an AUROC of 0.87 at BL, 0.85 at 1yFU and 0.81 at 4yFU and 33 KO [Kyoto Encyclopedia of Genes and Genomes (KEGG) ortholog] features with an AUROC of 0.79 at BL, 0.88 at 1yFU and 0.82 at 4yFU. Using ensemble learning for these three models, including a clinical model with the four parameters of age, gender, body mass index (BMI) and Apolipoprotein E (ApoE) genotype, yielded an AUROC of 0.96 at BL, 0.96 at 1yFU and 0.97 at 4yFU. In conclusion, we identified novel and timely stable gut microbiome algorithms that accurately predict progression to AD dementia in individuals with MCI over a 4yFU period.
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  • 文章类型: Journal Article
    背景:心脏骤停(CA)是危重患者死亡的主要原因。临床研究表明,早期发现CA可降低死亡率。已经使用多变量时间序列数据开发了能够以高灵敏度预测CA的算法。然而,这些算法的误报率很高,他们的结果是不能临床解释。
    目的:我们提出了一种使用多分辨率统计特征和基于余弦相似性的特征来及时预测CA的集成方法。此外,这种方法提供了临床可解释的结果,可供临床医师采用.
    方法:使用来自重症监护IV医疗信息集市数据库和eICU合作研究数据库的数据对患者进行回顾性分析。根据诊断为心力衰竭的成年人的24小时时间窗的多变量生命体征,我们提取了基于多分辨率统计和余弦相似度的特征。这些特征用于构造和开发梯度增强决策树。因此,我们采用了成本敏感学习作为解决方案。然后,进行了10倍交叉验证,以检查模型性能的一致性,Shapley加性解释算法用于捕获所提出模型的整体可解释性。接下来,使用eICU协作研究数据库进行外部验证,以检查泛化能力.
    结果:所提出的方法产生0.86的总体接受者工作特征曲线下面积(AUROC)和0.58的精确度-召回曲线下面积(AUPRC)。就CA的及时预测而言,所提出的模型实现了AUROC高于0.80,可提前6小时预测CA事件.所提出的方法同时提高了精度和灵敏度,提高了AUPRC,这减少了错误警报的数量,同时保持高灵敏度。该结果表明,所提出的模型的预测性能优于先前研究中报告的模型的性能。接下来,我们证明了特征重要性对所提出方法的临床可解释性的影响,并推断了非CA组和CA组之间的影响.最后,使用eICU合作研究数据库进行外部验证,在一般重症监护病房人群中获得的AUROC为0.74,AUPRC为0.44.
    结论:提出的框架可通过内部和外部验证为临床医生提供更准确的CA预测结果,并降低误报率。此外,临床可解释的预测结果可以帮助临床医生理解。此外,生命体征变化的相似性可以为心力衰竭相关诊断患者CA预测的时间模式变化提供见解。因此,我们的系统对于常规临床应用是足够可行的.此外,关于拟议的CA预测系统,在未来的数字健康领域已经开发并验证了临床上成熟的应用。
    Cardiac arrest (CA) is the leading cause of death in critically ill patients. Clinical research has shown that early identification of CA reduces mortality. Algorithms capable of predicting CA with high sensitivity have been developed using multivariate time series data. However, these algorithms suffer from a high rate of false alarms, and their results are not clinically interpretable.
    We propose an ensemble approach using multiresolution statistical features and cosine similarity-based features for the timely prediction of CA. Furthermore, this approach provides clinically interpretable results that can be adopted by clinicians.
    Patients were retrospectively analyzed using data from the Medical Information Mart for Intensive Care-IV database and the eICU Collaborative Research Database. Based on the multivariate vital signs of a 24-hour time window for adults diagnosed with heart failure, we extracted multiresolution statistical and cosine similarity-based features. These features were used to construct and develop gradient boosting decision trees. Therefore, we adopted cost-sensitive learning as a solution. Then, 10-fold cross-validation was performed to check the consistency of the model performance, and the Shapley additive explanation algorithm was used to capture the overall interpretability of the proposed model. Next, external validation using the eICU Collaborative Research Database was performed to check the generalization ability.
    The proposed method yielded an overall area under the receiver operating characteristic curve (AUROC) of 0.86 and area under the precision-recall curve (AUPRC) of 0.58. In terms of the timely prediction of CA, the proposed model achieved an AUROC above 0.80 for predicting CA events up to 6 hours in advance. The proposed method simultaneously improved precision and sensitivity to increase the AUPRC, which reduced the number of false alarms while maintaining high sensitivity. This result indicates that the predictive performance of the proposed model is superior to the performances of the models reported in previous studies. Next, we demonstrated the effect of feature importance on the clinical interpretability of the proposed method and inferred the effect between the non-CA and CA groups. Finally, external validation was performed using the eICU Collaborative Research Database, and an AUROC of 0.74 and AUPRC of 0.44 were obtained in a general intensive care unit population.
    The proposed framework can provide clinicians with more accurate CA prediction results and reduce false alarm rates through internal and external validation. In addition, clinically interpretable prediction results can facilitate clinician understanding. Furthermore, the similarity of vital sign changes can provide insights into temporal pattern changes in CA prediction in patients with heart failure-related diagnoses. Therefore, our system is sufficiently feasible for routine clinical use. In addition, regarding the proposed CA prediction system, a clinically mature application has been developed and verified in the future digital health field.
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  • 文章类型: Journal Article
    阿尔茨海默病(AD)是痴呆的最常见原因。AD及其前驱期的准确预测和诊断,即,轻度认知障碍(MCI),对于疾病的可能延迟和早期治疗至关重要。在本文中,我们采用中国纵向老龄化研究(CLAS)的数据,该项目于2011年启动,包括全国15个机构的共同努力。四千四百一十一人至少60岁参加了这个项目,3,514人完成了基线调查。调查收集了包括人口统计信息在内的数据,日常生活方式,病史,和常规体检。特别是,我们使用集成学习和特征选择方法来开发AD和MCI的可解释预测模型。应用五种特征选择方法和九种机器学习分类器进行比较,以找到AD/MCI预测中最主要的特征。所得到的模型达到了89.2%的准确率,灵敏度为87.7%,MCI预测的特异性为90.7%,准确率为99.2%,灵敏度为99.7%,AD预测的特异性为98.7%。我们进一步利用SHapley加法扩张(SHAP)算法在全球和个人层面上可视化每个特征对AD/MCI预测的具体贡献。因此,我们的模型不仅提供了预测结果,但也有助于了解生活方式/身体疾病史和认知功能之间的关系,并使临床医生能够为老年人提出适当的建议。因此,我们的方法为AD和MCI的计算机辅助诊断系统的设计提供了新的视角,具有潜在的高临床应用价值。
    Alzheimer\'s disease (AD) is the most common cause of dementia. Accurate prediction and diagnosis of AD and its prodromal stage, i.e., mild cognitive impairment (MCI), is essential for the possible delay and early treatment for the disease. In this paper, we adopt the data from the China Longitudinal Aging Study (CLAS), which was launched in 2011, and includes a joint effort of 15 institutions all over the country. Four thousand four hundred and eleven people who are at least 60 years old participated in the project, where 3,514 people completed the baseline survey. The survey collected data including demographic information, daily lifestyle, medical history, and routine physical examination. In particular, we employ ensemble learning and feature selection methods to develop an explainable prediction model for AD and MCI. Five feature selection methods and nine machine learning classifiers are applied for comparison to find the most dominant features on AD/MCI prediction. The resulting model achieves accuracy of 89.2%, sensitivity of 87.7%, and specificity of 90.7% for MCI prediction, and accuracy of 99.2%, sensitivity of 99.7%, and specificity of 98.7% for AD prediction. We further utilize the SHapley Additive exPlanations (SHAP) algorithm to visualize the specific contribution of each feature to AD/MCI prediction at both global and individual levels. Consequently, our model not only provides the prediction outcome, but also helps to understand the relationship between lifestyle/physical disease history and cognitive function, and enables clinicians to make appropriate recommendations for the elderly. Therefore, our approach provides a new perspective for the design of a computer-aided diagnosis system for AD and MCI, and has potential high clinical application value.
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  • 文章类型: Journal Article
    在这项研究中,已经提出了一种预测算法,以快速计算中子辐射场的核爆炸在复杂的地形场景下,基于集成学习方法,这对于传统的辐射传输模拟方法来说可能是不可能的。通过分析复杂表面形貌对辐射场的影响,利用DEM提取了一系列表征地形特征及其对中子和二次伽马在大气中输运的影响的特征参数,并利用随机算法生成的地形样本的MC模拟结果构造样本,用于训练核爆炸中子辐射场的预测模型。为了验证模型的实际预测性能,这项研究已经实现了中子通量的预测,在真实的城市和山区地形情景下,中子组织剂量和次级伽马组织剂量,并对不同评价维度下的快速预测和MC仿真结果进行了分析比较。比较表明,两个结果彼此吻合良好,表明该快速预测模型初步具有工程应用价值。此外,提出了一种可行的方法来提高各种辐射场景预测模型的泛化性能,这可以作为进一步研究的参考。
    In this study a prediction algorithm has been proposed to rapidly figure out neutron radiation field for nuclear explosion under complex terrain scenario based on ensemble learning approach, which could be an impossibility for traditional radiation transport simulation methodology. By analyzing the influence of complex surface morphology on the radiation field, a series of characteristic parameters which could characterize the topographic features and their influence on the transport of neutrons and secondary gamma in the atmosphere have been extracted with the application of DEM, and the sample sethas been constructedwith the MC simulation results of terrain samples generated by random algorithm, to be used to train the prediction model for the neutron radiation field of nuclear explosion. In order to verify the actual prediction performance of the model, the study has implemented the prediction for the neutron flux, neutron tissue dose and secondary gamma tissue dose under the authentic urban and mountainous terrain scenarios, and analyzed and compared the results from fast prediction and MC simulation in different evaluation dimensions. The comparisons suggest that both of the results are in good agreement with each other, demonstrating that the fast prediction models preliminarily possess the engineering application value. In addition, a feasible approach to improve the generalization performance of the prediction model for various radiation scenarios has been proposed, which could be deemed as a reference for further research.
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  • 文章类型: Journal Article
    引入新的临床风险评分(例如欧洲心脏手术风险评估系统(EuroSCORE)II)取代具有不同变量集的原始评分(例如EuroSCOREI)通常会导致不同的数据集,这是由于在采用之前对新评分变量的错误程度很高。对于使用集成学习来合并来自传统分数的不同数据知之甚少。我们测试了以下假设:同质和异质机器学习(ML)集合将比动态模型平均(DMA)集合具有更好的性能,可以将来自EuroSCOREI遗留数据的知识与EuroSCOREII数据相结合以预测心脏手术风险。
    使用全国成人心脏外科手术审核数据集,我们训练了12个不同的基础学习模型,基于来自EuroSCOREI(LogES)或EuroScoreII(ESII)的两个不同变量集,按采用分数的时间(1996-2016年或2012-2016年)进行划分,并根据保留集(2017-2019年)进行评估。这些基础学习器模型使用六种ML算法的九种不同组合进行整合,以产生同质或异质集合。使用共识指标评估绩效。
    Xgboost同质集合(HE)是性能最高的模型(临床有效性度量(CEM)0.725),曲线下面积(AUC)(0.8327;95%置信区间(CI)0.8323-0.8329),其次是随机森林HE(CEM0.723;AUC0.8325;950.8320-0.8326)。在不同的异质合奏中,通过组合跨时间的孤立数据集(CEM0.720)比构建1996-2011年的集合(t检验调整后,p=1.67×10-6)或2012-2019(t检验调整,p=1.35×10-193)单独的数据集。
    同质和异质ML集合的性能明显优于贝叶斯更新模型的DMA集合。变量的时间相关集合组合,根据分数采用的时间有不同的素质,启用了要合并的先前孤立的数据,导致功率增加,变量的临床可解释性和数据的使用。
    UNASSIGNED: The introduction of new clinical risk scores (e.g. European System for Cardiac Operative Risk Evaluation (EuroSCORE) II) superseding original scores (e.g. EuroSCORE I) with different variable sets typically result in disparate datasets due to high levels of missingness for new score variables prior to time of adoption. Little is known about the use of ensemble learning to incorporate disparate data from legacy scores. We tested the hypothesised that Homogenenous and Heterogeneous Machine Learning (ML) ensembles will have better performance than ensembles of Dynamic Model Averaging (DMA) for combining knowledge from EuroSCORE I legacy data with EuroSCORE II data to predict cardiac surgery risk.
    UNASSIGNED: Using the National Adult Cardiac Surgery Audit dataset, we trained 12 different base learner models, based on two different variable sets from either EuroSCORE I (LogES) or EuroScore II (ES II), partitioned by the time of score adoption (1996-2016 or 2012-2016) and evaluated on holdout set (2017-2019). These base learner models were ensembled using nine different combinations of six ML algorithms to produce homogeneous or heterogeneous ensembles. Performance was assessed using a consensus metric.
    UNASSIGNED: Xgboost homogenous ensemble (HE) was the highest performing model (clinical effectiveness metric (CEM) 0.725) with area under the curve (AUC) (0.8327; 95% confidence interval (CI) 0.8323-0.8329) followed by Random Forest HE (CEM 0.723; AUC 0.8325; 95%CI 0.8320-0.8326). Across different heterogenous ensembles, significantly better performance was obtained by combining siloed datasets across time (CEM 0.720) than building ensembles of either 1996-2011 (t-test adjusted, p = 1.67×10-6) or 2012-2019 (t-test adjusted, p = 1.35×10-193) datasets alone.
    UNASSIGNED: Both homogenous and heterogenous ML ensembles performed significantly better than DMA ensemble of Bayesian Update models. Time-dependent ensemble combination of variables, having differing qualities according to time of score adoption, enabled previously siloed data to be combined, leading to increased power, clinical interpretability of variables and usage of data.
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  • 文章类型: Journal Article
    软件缺陷预测(SDP)是软件开发生命周期(SDLC)的一个组成部分。随着软件系统的普及,越来越多地融入我们的日常生活,因此,这些系统的复杂性增加了广泛缺陷的风险。随着对这些系统的依赖增加,使用机器学习(ML)准确识别有缺陷的模型的能力被忽视和较少解决。因此,本文对SDP的各种ML技术进行了研究。一项调查,比较分析和推荐适当的特征提取(FE)技术,主成分分析(PCA),偏最小二乘回归(PLS),特征选择(FS)技术,费舍尔得分,递归特征消除(RFE),和弹性网。验证以下技术,无论是单独还是与ML算法结合,执行:支持向量机(SVM),逻辑回归(LR),朴素贝叶斯(NB),K-近邻(KNN),多层感知器(MLP),决策树(DT)和集成学习方法引导聚合(Bagging),自适应提升(AdaBoost),极端梯度提升(XGBoost),随机森林(RF),和广义堆叠(Stacking)。建立了广泛的实验设置,实验结果表明,FE和FS可以积极和消极地影响基本模型或基线的性能。PLS,无论是单独还是与FS技术结合,提供令人印象深刻的,最一致的,改进,而PCA,结合Elastic-Net,显示出可接受的改进。
    Software Defect Prediction (SDP) is an integral aspect of the Software Development Life-Cycle (SDLC). As the prevalence of software systems increases and becomes more integrated into our daily lives, so the complexity of these systems increases the risks of widespread defects. With reliance on these systems increasing, the ability to accurately identify a defective model using Machine Learning (ML) has been overlooked and less addressed. Thus, this article contributes an investigation of various ML techniques for SDP. An investigation, comparative analysis and recommendation of appropriate Feature Extraction (FE) techniques, Principal Component Analysis (PCA), Partial Least Squares Regression (PLS), Feature Selection (FS) techniques, Fisher score, Recursive Feature Elimination (RFE), and Elastic Net are presented. Validation of the following techniques, both separately and in combination with ML algorithms, is performed: Support Vector Machine (SVM), Logistic Regression (LR), Naïve Bayes (NB), K-Nearest Neighbour (KNN), Multilayer Perceptron (MLP), Decision Tree (DT), and ensemble learning methods Bootstrap Aggregation (Bagging), Adaptive Boosting (AdaBoost), Extreme Gradient Boosting (XGBoost), Random Forest(RF), and Generalized Stacking (Stacking). Extensive experimental setup was built and the results of the experiments revealed that FE and FS can both positively and negatively affect performance over the base model or Baseline. PLS, both separately and in combination with FS techniques, provides impressive, and the most consistent, improvements, while PCA, in combination with Elastic-Net, shows acceptable improvement.
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