Adaptive modeling

  • 文章类型: Journal Article
    先前的研究展示了使用在线电容谱准确预测细胞死亡百分比的偏最小二乘(PLS)回归模型。当前的研究通过采用数据融合方法的自适应建模来提高模型精度。该策略通过结合Cole-Cole模型中的变量来增强预测性能,电导率及其随时间的衍生物,和马氏距离进入预测矩阵(X矩阵)。首先,Cole-Cole模型,具有与早期细胞死亡发作相关的参数的机械模型,被集成以增强预测性能。其次,在X矩阵中包含电导率及其随时间的导数减轻了由于过程操作期间电导率突然变化而导致的预测波动。第三,马氏距离,描绘相对于上一个时间点的参考光谱的光谱变化,改进了模型对独立测试集的适应性,从而提高性能。最终的数据融合模型显著降低了预测的均方根误差(RMSEP)约50%,与现有的PLS模型相比,这显著提高了预测精度。通过在各个时间点的一致性能证实了对参考光谱选择的鲁棒性。总之,这项研究表明,与以前的模型相比,数据融合策略大大提高了模型的准确性仅仅依靠电容谱。
    The previous research showcased a partial least squares (PLS) regression model accurately predicting cell death percentages using in-line capacitance spectra. The current study advances the model accuracy through adaptive modeling employing a data fusion approach. This strategy enhances prediction performance by incorporating variables from the Cole-Cole model, conductivity and its derivatives over time, and Mahalanobis distance into the predictor matrix (X-matrix). Firstly, the Cole-Cole model, a mechanistic model with parameters linked to early cell death onset, was integrated to enhance prediction performance. Secondly, the inclusion of conductivity and its derivatives over time in the X-matrix mitigated prediction fluctuations resulting from abrupt conductivity changes during process operations. Thirdly, Mahalanobis distance, depicting spectral changes relative to a reference spectrum from a previous time point, improved model adaptability to independent test sets, thereby enhancing performance. The final data fusion model substantially decreased root-mean squared error of prediction (RMSEP) by around 50%, which is a significant boost in prediction accuracy compared to the prior PLS model. Robustness against reference spectrum selection was confirmed by consistent performance across various time points. In conclusion, this study illustrates that the data fusion strategy substantially enhances the model accuracy compared to the previous model relying solely on capacitance spectra.
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  • 文章类型: Journal Article
    简介:膝关节骨性关节炎(KOA)的特征是关节软骨退变。机械关节环境在这种疾病的发生和发展中起着重要作用,这已被广泛接受。计算机模型已用于研究机械负荷和软骨退化之间的相互作用,因此主要依赖于指示胶原降解和蛋白聚糖消耗的两个关键机械调节因子。这些因素分别是胶原纤维方向的应变(SFD)和最大剪切应变(MSS)。方法:在本研究中,基于肌肉骨骼和有限元建模之间的协同作用,使用多尺度计算机建模方法来评估SFD和MSS。基于在基线(在2年随访之前)收集的受试者特异性步态分析数据,在步态期间评估具有相似人口统计学的健康和进行性早期KOA受试者的这些菌株。结果:结果表明,SFD和MSS因素允许区分健康受试者和KOA受试者,在2年随访时显示进展,在峰值接触力的情况下以及在步态周期的站立阶段。在站立阶段的高峰期,发现KOA患者的SFD更高,与健康受试者相比,胫骨软骨外侧区的中位数高0.82%,内侧区高0.4%.同样,对于MSS来说,与健康受试者相比,KOA患者的胫骨外侧区和内侧区的中位应变分别高出3.6%和0.7%.基于这些主体间的SFD和MSS差异,我们还能够确定KOA患者的胫骨室有进展的风险.结论/讨论:我们证实了机械调节因子是区分疾病进展风险患者的潜在生物标志物。未来的研究应该评估基于这种多尺度建模工作流程在更大的患者和对照组中计算的机械调节因子的敏感性。
    Introduction: Knee osteoarthritis (KOA) is characterized by articular cartilage degeneration. It has been widely accepted that the mechanical joint environment plays a significant role in the onset and progression of this disease. In silico models have been used to study the interplay between mechanical loading and cartilage degeneration, hereby relying mainly on two key mechanoregulatory factors indicative of collagen degradation and proteoglycans depletion. These factors are the strain in collagen fibril direction (SFD) and maximum shear strain (MSS) respectively. Methods: In this study, a multi-scale in silico modeling approach was used based on a synergy between musculoskeletal and finite element modeling to evaluate the SFD and MSS. These strains were evaluated during gait based on subject-specific gait analysis data collected at baseline (before a 2-year follow-up) for a healthy and progressive early-stage KOA subject with similar demographics. Results: The results show that both SFD and MSS factors allowed distinguishing between a healthy subject and a KOA subject, showing progression at 2 years follow-up, at the instance of peak contact force as well as during the stance phase of the gait cycle. At the peak of the stance phase, the SFD were found to be more elevated in the KOA patient with the median being 0.82% higher in the lateral and 0.4% higher in the medial compartment of the tibial cartilage compared to the healthy subject. Similarly, for the MSS, the median strains were found to be 3.6% higher in the lateral and 0.7% higher in the medial tibial compartment of the KOA patient compared to the healthy subject. Based on these intersubject SFD and MSS differences, we were additionally able to identify that the tibial compartment of the KOA subject at risk of progression. Conclusion/discussion: We confirmed the mechanoregulatory factors as potential biomarkers to discriminate patients at risk of disease progression. Future studies should evaluate the sensitivity of the mechanoregulatory factors calculated based on this multi-scale modeling workflow in larger patient and control cohorts.
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  • 文章类型: Journal Article
    强化和连续的过程需要快速而稳健的方法和技术来监测产品滴度,以加快分析周转时间。过程监控,和过程控制。当前的滴度测量大多是基于离线色谱的方法,其可能需要数小时甚至数天才能从分析实验室获得结果。因此,离线方法将不能满足连续生产和捕获过程的实时滴度测量的要求。FTIR和基于化学计量学的多变量建模是用于澄清散装(CB)收获物和灌注液线中实时滴度监测的有前途的工具。然而,已知经验模型容易受到看不见的可变性的影响,特别地,在给定的生物分子和工艺条件上训练的FTIR化学计量滴度模型通常不能提供在不同工艺条件下另一分子的滴度的准确预测。在这项研究中,我们开发了一种自适应建模策略:该模型最初是使用可用灌注液和CB样品的校准集构建的,然后通过将新分子的加标样品增加到校准集来更新,以使模型对新分子的灌注液或CB收获具有鲁棒性.该策略显著提高了模型性能,并且显著降低了新分子的建模工作量。
    Intensified and continuous processes require fast and robust methods and technologies to monitor product titer for faster analytical turnaround time, process monitoring, and process control. The current titer measurements are mostly offline chromatography-based methods which may take hours or even days to get the results back from the analytical labs. Thus, offline methods will not meet the requirement of real time titer measurements for continuous production and capture processes. FTIR and chemometric based multivariate modeling are promising tools for real time titer monitoring in clarified bulk (CB) harvests and perfusate lines. However, empirical models are known to be vulnerable to unseen variability, specifically a FTIR chemometric titer model trained on a given biological molecule and process conditions often fails to provide accurate predictions of titer in another molecule under different process conditions. In this study, we developed an adaptive modeling strategy: the model was initially built using a calibration set of available perfusate and CB samples and then updated by augmenting spiking samples of the new molecules to the calibration set to make the model robust against perfusate or CB harvest of the new molecule. This strategy substantially improved the model performance and significantly reduced the modeling effort for new molecules.
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  • 文章类型: Journal Article
    通常在耗时的手动程序中为单个生物过程开发和校准软传感器概念。在此之后,这些软传感器的预测性能会随着时间的推移而下降,由于原材料的变化,生物变异性,和修改的过程策略。通过自动适应和重新校准,自适应软传感器概念具有推广软传感器原理并使其适用于整个生物过程的潜力。在这项研究中,开发了一种新的广义自适应算法,用于基于多路主成分分析的软传感器的相位相关重新校准。相似性分析,和强大的,多相生物过程中的通用相位检测。在具有各种目标值的两个多相生物过程中评估了这种通用软传感器概念,媒体,和微生物。因此,软传感器概念在巴斯德毕赤酵母过程中用于生物量预测,以及枯草芽孢杆菌过程中的生物量和蛋白质预测,其中工艺特征(栽培培养基和栽培策略)各不相同。在分批和补料分批阶段,巴斯德毕赤酵母工艺(相对误差=6.9%)以及两种不同培养基中的枯草芽孢杆菌工艺(优化的高性能培养基中的相对误差:生物量预测=12.2%,蛋白质预测=7.2%;标准培养基中的相对误差:生物量预测=12.8%,蛋白质预测=8.8%)。
    A soft sensor concept is typically developed and calibrated for individual bioprocesses in a time-consuming manual procedure. Following that, the prediction performance of these soft sensors degrades over time, due to changes in raw materials, biological variability, and modified process strategies. Through automatic adaptation and recalibration, adaptive soft sensor concepts have the potential to generalize soft sensor principles and make them applicable across bioprocesses. In this study, a new generalized adaptation algorithm for soft sensors is developed to provide phase-dependent recalibration of soft sensors based on multiway principal component analysis, a similarity analysis, and robust, generalist phase detection in multiphase bioprocesses. This generalist soft sensor concept was evaluated in two multiphase bioprocesses with various target values, media, and microorganisms. Consequently, the soft sensor concept was tested for biomass prediction in a Pichia pastoris process, and biomass and protein prediction in a Bacillus subtilis process, where the process characteristics (cultivation media and cultivation strategy) were varied. High prediction performance was demonstrated for P. pastoris processes (relative error = 6.9%) as well as B. subtilis processes in two different media during batch and fed-batch phases (relative errors in optimized high-performance medium: biomass prediction = 12.2%, protein prediction = 7.2%; relative errors in standard medium: biomass prediction = 12.8%, protein prediction = 8.8%).
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  • 文章类型: Journal Article
    目的:目前的实验方法无法阐明骨关节炎(OA)变性过程中适应不良变化对主要软骨成分的影响。在硅方法中,然而,允许创建“虚拟敲除”案例,以特定于成分的方式阐明这些影响。我们使用这种方法来研究与以下OA病因相关的不同机械负荷下软骨退化的主要机制:(i)退化软骨的生理负荷,(ii)健康完整软骨的损伤负荷和(iii)具有局灶性缺损的软骨的生理负荷。
    方法:我们使用最近开发的软骨自适应复位退变(CARED)框架来模拟与原发性和继发性OA相关的软骨退变(OA病例(i)-(iii))。CARED结合了OA中组织水平软骨退变机制的数值描述,即,胶原蛋白降解,胶原蛋白重新定向,固定电荷密度损失和组织水化增加后的机械负荷。我们通过在三个OA案例中的每个案例中一次一个地停用这些退化过程来创建“虚拟敲除”场景。
    结果:在退化软骨的完整和生理负荷的有害负荷中,胶原蛋白降解通过固定电荷密度损失和组织水化上升驱动退行性变化。相比之下,后两种机制在局灶性缺损软骨模型中更为突出。
    结论:虚拟敲除模型显示,完整软骨的损伤负荷和退化软骨的生理负荷可引起胶原网络的初始退行性变化,然而,在存在局灶性软骨缺损的情况下,机械加载最初会导致PG耗尽,在胶原蛋白原纤维网络发生变化之前。
    Current experimental approaches cannot elucidate the effect of maladaptive changes on the main cartilage constituents during the degeneration process in osteoarthritis (OA). In silico approaches, however, allow creating \'virtual knock-out\' cases to elucidate these effects in a constituent-specific manner. We used such an approach to study the main mechanisms of cartilage degeneration in different mechanical loadings associated with the following OA etiologies: (1) physiological loading of degenerated cartilage, (2) injurious loading of healthy intact cartilage and (3) physiological loading of cartilage with a focal defect.
    We used the recently developed Cartilage Adaptive REorientation Degeneration (CARED) framework to simulate cartilage degeneration associated with primary and secondary OA (OA cases (1)-(3)). CARED incorporates numerical description of tissue-level cartilage degeneration mechanisms in OA, namely, collagen degradation, collagen reorientation, fixed charged density loss and tissue hydration increase following mechanical loading. We created \'virtual knock-out\' scenarios by deactivating these degenerative processes one at a time in each of the three OA cases.
    In the injurious loading of intact and physiological loading of degenerated cartilage, collagen degradation drives degenerative changes through fixed charge density loss and tissue hydration rise. In contrast, the two later mechanisms were more prominent in the focal defect cartilage model.
    The virtual knock-out models reveal that injurious loading to intact cartilage and physiological loading to degenerated cartilage induce initial degenerative changes in the collagen network, whereas, in the presence of a focal cartilage defect, mechanical loading initially causes proteoglycans (PG) depletion, before changes in the collagen fibril network occur.
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  • 文章类型: Journal Article
    软传感器的准确性和精度在很大程度上取决于基础模型输入的可靠性。这些输入(特别是硬件传感器的读数)经常发生故障。这项研究旨在开发一种自适应软传感器,该传感器能够在巴斯德毕赤酵母生物过程存在错误模型输入的情况下进行可靠和可靠的生物量浓度预测。因此,基于三个独立的模型输入开发了三个软测量子模型(基数加法,二氧化碳生产,和中红外光谱)。基于集成的算法将子模型组合起来形成一个集成模型,也就是说,自适应软传感器,实现容错预测。该算法的基本步骤如下:子模型可靠性的初始确定之后是选择适当的子模型以经由子模型的基于方差的加权来生成可靠的预测。在存在多个模拟传感器故障(RMSE=0.43gL-1)和多个真实传感器故障(RMSE=0.70gL-1)的情况下,自适应软传感器在生物量预测中表现出很高的鲁棒性和准确性。
    The accuracy and precision of soft sensors depend strongly on the reliability of underlying model inputs. These inputs (particularly readings of hardware sensors) are frequently subject to faults. This study aims to develop an adaptive soft sensor capable of reliable and robust biomass concentration predictions in the presence of faulty model inputs for a Pichia pastoris bioprocess. Hence, three soft sensor submodels were developed based on three independent model inputs (base addition, CO2 production, and mid-infrared spectrum). An ensemble-based algorithm combined the submodels to form an ensemble model, that is, an adaptive soft sensor, to achieve fault-tolerant prediction. The algorithm\'s basic steps are as follows: the initial determination of submodel reliability is followed by selecting appropriate submodels to generate a reliable prediction via variance-based weighting of the submodels. The adaptive soft sensor demonstrated high robustness and accuracy in biomass prediction in the presence of multiple simulated sensor faults (RMSE = 0.43 g L-1) and multiple real sensor faults (RMSE = 0.70 g L-1).
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  • 文章类型: Journal Article
    Injurious mechanical loading of articular cartilage and associated lesions compromise the mechanical and structural integrity of joints and contribute to the onset and progression of cartilage degeneration leading to osteoarthritis (OA). Despite extensive in vitro and in vivo research, it remains unclear how the changes in cartilage composition and structure that occur during cartilage degeneration after injury, interact. Recently, in silico techniques provide a unique integrated platform to investigate the causal mechanisms by which the local mechanical environment of injured cartilage drives cartilage degeneration. Here, we introduce a novel integrated Cartilage Adaptive REorientation Degeneration (CARED) algorithm to predict the interaction between degenerative variations in main cartilage constituents, namely collagen fibril disorganization and degradation, proteoglycan (PG) loss, and change in water content. The algorithm iteratively interacts with a finite element (FE) model of a cartilage explant, with and without variable depth to full-thickness defects. In these FE models, intact and injured explants were subjected to normal (2 MPa unconfined compression in 0.1 s) and injurious mechanical loading (4 MPa unconfined compression in 0.1 s). Depending on the mechanical response of the FE model, the collagen fibril orientation and density, PG and water content were iteratively updated. In the CARED model, fixed charge density (FCD) loss and increased water content were related to decrease in PG content. Our model predictions were consistent with earlier experimental studies. In the intact explant model, minimal degenerative changes were observed under normal loading, while the injurious loading caused a reorientation of collagen fibrils toward the direction perpendicular to the surface, intense collagen degradation at the surface, and intense PG loss in the superficial and middle zones. In the injured explant models, normal loading induced intense collagen degradation, collagen reorientation, and PG depletion both on the surface and around the lesion. Our results confirm that the cartilage lesion depth is a crucial parameter affecting tissue degeneration, even under physiological loading conditions. The results suggest that potential fibril reorientation might prevent or slow down fibril degradation under conditions in which the tissue mechanical homeostasis is perturbed like the presence of defects or injurious loading.
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  • 文章类型: Journal Article
    越来越多的证据表明,反事实推理涉及错误的信念推理。因为现有的工作是相关的,我们开发了一种操纵方法,揭示了参与者对错误信念问题的回答中的反事实推理的签名。在两个实验中,我们测试了3至14岁的儿童,发现反事实和错误信念问题之间存在高度正相关(r=.56和r=.73)。孩子们很可能以相同的答案回答这两个问题,也提交相同类型的错误。我们讨论了不同的理论及其解释我们发现的各个方面的能力,并得出结论,对他人的信念和行为进行推理需要与使用反事实假设相似的认知过程。我们的发现质疑传统框架的解释力,理论理论和仿真理论,赞成明确规定错误信念推理和反事实推理之间关系的观点。
    Increasing evidence suggests that counterfactual reasoning is involved in false belief reasoning. Because existing work is correlational, we developed a manipulation that revealed a signature of counterfactual reasoning in participants\' answers to false belief questions. In two experiments, we tested 3- to 14-year-olds and found high positive correlations (r = .56 and r = .73) between counterfactual and false belief questions. Children were very likely to respond to both questions with the same answer, also committing the same type of error. We discuss different theories and their ability to account for each aspect of our findings and conclude that reasoning about others\' beliefs and actions requires similar cognitive processes as using counterfactual suppositions. Our findings question the explanatory power of the traditional frameworks, theory theory and simulation theory, in favor of views that explicitly provide for a relationship between false belief reasoning and counterfactual reasoning.
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  • 文章类型: Journal Article
    In this paper, we use an adaptive modeling framework to model and study how nutritional status (measured by the protein to carbohydrate ratio) may regulate population dynamics and foraging task allocation of social insect colonies. Mathematical analysis of our model shows that both investment to brood rearing and brood nutrition are important for colony survival and dynamics. When division of labour and/or nutrition are in an intermediate value range, the model undergoes a backward bifurcation and creates multiple attractors due to bistability. This bistability implies that there is a threshold population size required for colony survival. When the investment in brood is large enough or nutritional requirements are less strict, the colony tends to survive, otherwise the colony faces collapse. Our model suggests that the needs of colony survival are shaped by the brood survival probability, which requires good nutritional status. As a consequence, better nutritional status can lead to a better survival rate of larvae and thus a larger worker population.
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  • 文章类型: Comparative Study
    BACKGROUND: Advanced methods of signal analysis of the preictal and ictal activity dynamics characterizing absence epilepsy in humans with absences and in genetic animal models have revealed new and unknown electroencephalographic characteristics, that has led to new insights and theories.
    METHODS: Taking into account that some network associations can be considered as nonlinear, an adaptive nonlinear Granger causality approach was developed and applied to analyze cortico-cortical, cortico-thalamic and intrathalamic network interactions from local field potentials (LFPs). The outcomes of adaptive nonlinear models, constructed based on the properties of electroencephalographic signal and on statistical criteria to optimize the number of coefficients in the models, were compared with the outcomes of linear Granger causality.
    RESULTS: The nonlinear adaptive method showed statistically significant preictal changes in Granger causality in almost all pairs of channels, as well as ictal changes in cortico-cortical, cortico-thalamic and intrathalamic networks. Current results suggest rearrangement of interactions in the thalamo-cortical network accompanied the transition from preictal to ictal phase.
    CONCLUSIONS: The linear method revealed no preictal and less ictal changes in causality.
    CONCLUSIONS: Achieved results suggest that this proposed adaptive nonlinear method is more sensitive than the linear one to dynamics of network properties. Since changes in coupling were found before the seizure-related increase of LFP signal amplitude and also based on some additional tests it seems likely that they were not spurious and could not result from signal to noise ratio change.
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