modelling

建模
  • 文章类型: Journal Article
    在COVID-19大流行期间,数学建模在提供知情建议方面发挥了重要作用。在英国,一项跨政府和学术界的合作从一系列流行病学模型中对未来4-6周可能的流行病轨迹进行了中期预测(MTPs).在这篇文章中,我们概述了这种协作建模方法,并根据2021年11月至2022年12月期间各种Omicron亚变体在英格兰传播的数据评估了组合模型和单个模型预测的准确性.使用一些统计方法,我们量化了组合和单个MTP的模型预测的预测性能,通过评估点和概率准确性。我们的结果表明,合并的MTP,从一组异质流行病学模型中产生,在流行病增长或下降期间,比单个模型更接近数据,90%的置信区间在流行病高峰附近最宽。我们还表明,组合的MTP增加了鲁棒性,并减少了与单个模型投影相关的偏差。从我们在COVID-19流行期间的合奏建模经验中学习,我们的研究结果强调了发展跨机构多模式传染病中心对于未来疫情控制的重要性.
    Mathematical modelling has played an important role in offering informed advice during the COVID-19 pandemic. In England, a cross government and academia collaboration generated medium-term projections (MTPs) of possible epidemic trajectories over the future 4-6 weeks from a collection of epidemiological models. In this article, we outline this collaborative modelling approach and evaluate the accuracy of the combined and individual model projections against the data over the period November 2021-December 2022 when various Omicron subvariants were spreading across England. Using a number of statistical methods, we quantify the predictive performance of the model projections for both the combined and individual MTPs, by evaluating the point and probabilistic accuracy. Our results illustrate that the combined MTPs, produced from an ensemble of heterogeneous epidemiological models, were a closer fit to the data than the individual models during the periods of epidemic growth or decline, with the 90% confidence intervals widest around the epidemic peaks. We also show that the combined MTPs increase the robustness and reduce the biases associated with a single model projection. Learning from our experience of ensemble modelling during the COVID-19 epidemic, our findings highlight the importance of developing cross-institutional multi-model infectious disease hubs for future outbreak control.
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  • 文章类型: Journal Article
    脑细胞结构和功能反映神经发育,可塑性,和衰老;变化可以帮助标志病理过程,如神经变性和神经炎症。需要精确和定量的方法来无创地解开细胞结构特征,并且是大脑研究的重点。扩散加权MRS(dMRS)可以访问内源性细胞内脑代谢产物的扩散特性,这些代谢产物优先位于特定的脑细胞群内。尽管潜力巨大,DMRS在各个层面上仍然是一项具有挑战性的技术:从数据采集到分析,量化,建模,和结果的解释。这些挑战是洛伦兹中心在莱顿举行的“扩散磁共振波谱学最佳实践和工具”研讨会背后的动机,荷兰,2021年9月。在研讨会期间,dMRS社区建立了一套建议来执行稳健的dMRS研究。本文介绍了获取所需的步骤,processing,配件,并对DMRS数据进行建模,并提供有用资源的链接。
    Brain cell structure and function reflect neurodevelopment, plasticity, and aging; and changes can help flag pathological processes such as neurodegeneration and neuroinflammation. Accurate and quantitative methods to noninvasively disentangle cellular structural features are needed and are a substantial focus of brain research. Diffusion-weighted MRS (dMRS) gives access to diffusion properties of endogenous intracellular brain metabolites that are preferentially located inside specific brain cell populations. Despite its great potential, dMRS remains a challenging technique on all levels: from the data acquisition to the analysis, quantification, modeling, and interpretation of results. These challenges were the motivation behind the organization of the Lorentz Center workshop on \"Best Practices & Tools for Diffusion MR Spectroscopy\" held in Leiden, the Netherlands, in September 2021. During the workshop, the dMRS community established a set of recommendations to execute robust dMRS studies. This paper provides a description of the steps needed for acquiring, processing, fitting, and modeling dMRS data, and provides links to useful resources.
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  • 文章类型: Journal Article
    暂无摘要。
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  • 文章类型: Journal Article
    目的:我们的目的是使用一种高保真计算模型,该模型可以捕获心血管系统和肺系统之间的关键相互作用,以研究当前的CPR方案是否可能得到改进。
    方法:我们根据现有的人类数据开发并验证了计算模型。我们使用全局优化算法来找到CPR协议参数,这些参数优化了与10名虚拟受试者队列中自发循环返回相关的输出。
    结果:与当前协议相比,心肌组织氧容量高出5倍以上,脑组织氧容量几乎增加了一倍,在优化CPR期间。虽然使用我们的模型发现的最佳最大胸骨位移(5.5cm)和压缩比(51%)与当前的美国心脏协会指南一致,最佳胸部按压率较低(67次按压min-1)。同样,最优通风策略比现行指南更保守,具有1500mlmin-1的最佳分钟通气量和80%的氧气吸入分数。末端压缩力是对CO影响最大的参数,其次是PEEP,压缩比和CC速率。
    结论:我们的结果表明,当前的CPR方案可能会得到改进。心肺复苏期间过度通气可能对器官氧合有害,由于肺血管阻力增加的负血流动力学作用。应特别注意胸部按压力,以达到满意的CO。旨在开发改进的CPR方案的未来临床试验应明确考虑胸部按压和通气参数之间的相互作用。
    We aimed to use a high-fidelity computational model that captures key interactions between the cardiovascular and pulmonary systems to investigate whether current CPR protocols could potentially be improved.
    We developed and validated the computational model against available human data. We used a global optimisation algorithm to find CPR protocol parameters that optimise the outputs associated with return of spontaneous circulation in a cohort of 10 virtual subjects.
    Compared with current protocols, myocardial tissue oxygen volume was more than 5 times higher, and cerebral tissue oxygen volume was nearly doubled, during optimised CPR. While the optimal maximal sternal displacement (5.5 cm) and compression ratio (51%) found using our model agreed with the current American Heart Association guidelines, the optimal chest compression rate was lower (67 compressions min-1). Similarly, the optimal ventilation strategy was more conservative than current guidelines, with an optimal minute ventilation of 1500 ml min-1 and inspired fraction of oxygen of 80%. The end compression force was the parameter with the largest impact on CO, followed by PEEP, the compression ratio and the CC rate.
    Our results indicate that current CPR protocols could potentially be improved. Excessive ventilation could be detrimental to organ oxygenation during CPR, due to the negative haemodynamic effect of increased pulmonary vascular resistance. Particular attention should be given to the chest compression force to achieve satisfactory CO. Future clinical trials aimed at developing improved CPR protocols should explicitly consider interactions between chest compression and ventilation parameters.
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  • 文章类型: Journal Article
    背景:减少慢性病的国际策略要求减少饱和脂肪(SAFA)的含量,反式脂肪(TFA),全球粮食供应中的盐和糖。本文介绍了这些营养素驱动食品(重新)配方的一套标准的开发方法和潜在影响。
    方法:要设置标准,WHO每日摄入量的营养素指南已转化为产品组特定标准。使用五个国家的食物消费数据模拟了重新制定这些标准对人口营养素摄入量的影响:英国,法国,US,巴西和中国。由于缺乏数据,TFA标准的影响无法建模。
    结果:(重新)制定符合这些标准的食品和饮料将大大减少人口的平均能量摄入量,钠,SAFA和糖,减少高达30%。
    结论:这些基于科学的营养限制标准可能会导致能量减少,钠,食品和饮料产品中的SAFA和糖,使平均人口摄入量更接近世卫组织营养素指南。
    BACKGROUND: International strategies to reduce chronic diseases have called for a reduction in the amounts of saturated fat (SAFA), trans fat (TFA), salt and sugars in the global food supply. This paper describes the development approach and potential impact of a set of standards for these nutrients to drive food (re)formulation.
    METHODS: To set the standards, WHO nutrient guidelines for daily intake were translated into product group specific standards. The impact of reformulation towards these standards on population nutrient intakes was modelled using the food consumption data of five countries: UK, France, US, Brazil and China. The impact of the TFA standards could not be modelled due to lack of data.
    RESULTS: (Re)formulation of foods and beverages towards these standards would substantially decrease mean population intakes of energy, sodium, SAFA and sugars, with reductions up to 30%.
    CONCLUSIONS: These science-based standards for nutrients to limit could drive impactful reductions in energy, sodium, SAFA and sugars in food and beverage products, enabling mean population intakes to move closer to WHO nutrient guidelines.
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  • 文章类型: Letter
    COVID-19大流行带来了公共卫生的综合学科,传染病和政策建模正成为人们关注的焦点。关于公共卫生措施及其影响的决定从未成为国际审议的主题,从个人和社区到全球领导者。在决策过程中,快速开发的模型也没有如此重要,而且往往是在缺乏完整信息的情况下开发的。然而,经过近3年的建模经验,政策制定者需要对哪些模型在做出公共卫生决策时最有助于支持他们更有信心,建模者需要更好地了解将导致成功采用和利用模型的因素。我们提出了实现这些目标的三阶段框架。
    The COVID-19 pandemic has brought the combined disciplines of public health, infectious disease and policy modelling squarely into the spotlight. Never before have decisions regarding public health measures and their impacts been such a topic of international deliberation, from the level of individuals and communities through to global leaders. Nor have models-developed at rapid pace and often in the absence of complete information-ever been so central to the decision-making process. However, after nearly 3 years of experience with modelling, policy-makers need to be more confident about which models will be most helpful to support them when taking public health decisions, and modellers need to better understand the factors that will lead to successful model adoption and utilization. We present a three-stage framework for achieving these ends.
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  • 文章类型: Journal Article
    COVID-19 has highlighted the need for credible epidemiological models to inform pandemic policy. Traditional mechanisms of commissioning research are ill-suited to guide policy during a rapidly evolving pandemic. At the same time, contracting with a single centre of expertise has been criticized for failing to reflect challenges inherent in specific modelling approaches.
    This report describes an alternative approach to mobilizing scientific expertise. Ontario\'s COVID-19 Modelling Consensus Table (MCT) was created in March 2020 to enable rapid communication of credible estimates of the impact of COVID-19 and to accelerate learning on how the disease is spreading and what could slow its transmission. The MCT is a partnership between the province and academic modellers and consists of multiple groups of experts, health system leaders, and senior decision-makers. Armed with Ministry of Health data, the MCT meets once per week to share results from modelling exercises, generate consensus judgements of the likely future impact of COVID-19, and discuss decision-makers\' priorities.
    The MCT has enabled swift access to data for participants, a structure for developing consensus estimates and communicating these to decision-makers, credible models to inform health system planning, and increased transparency in public reporting of COVID-19 data. It has also facilitated the rapid publication of research findings and its incorporation into government policy.
    The MCT approach is one way to quickly draw on scientific advice outside of government and public health agencies. Beyond speed, this approach allows for nimbleness as experts from different organizations can be added as needed. It also shows how universities and research institutes have a role to play in crisis situations, and how this expertise can be marshalled to inform policy while respecting academic freedom and confidentiality.
    RéSUMé: LIEU: La COVID-19 a mis en évidence le besoin de modèles épidémiologiques crédibles pour éclairer la politique pandémique. Les mécanismes habituels pour commander des travaux de recherche sont peu propices à orienter les politiques lors d’une pandémie qui évolue rapidement. En même temps, la passation de contrats avec un seul centre d’expertise est critiquée, car elle ne tient pas compte des difficultés inhérentes de certaines approches de modélisation. INTERVENTION: Le présent rapport décrit une approche de rechange pour mobiliser le savoir scientifique. L’Ontario a créé en mars 2020 une Table de concertation sur la modélisation (TCM) qui permet de communiquer de façon rapide et fiable les estimations des effets de la COVID-19 et d’apprendre plus vite comment la maladie se propage et ce qui pourrait en ralentir la transmission. La TCM, un partenariat entre les modélisateurs de la province et des milieux universitaires, est composée de plusieurs groupes d’experts, de dirigeants du système de santé et de décideurs de haut niveau. Armée des données du ministère de la Santé, la TCM se réunit une fois par semaine pour partager les résultats d’exercices de modélisation, générer des jugements consensuels sur les futurs effets probables de la COVID-19 et discuter des priorités des décideurs. RéSULTATS: La TCM rend possible un accès rapide aux données pour les participants, une structure pour élaborer des estimations consensuelles et les communiquer aux décideurs, des modèles fiables pour éclairer la planification du système de santé, ainsi qu’une transparence accrue dans la communication des données sur la COVID-19 au public. Elle facilite aussi la publication rapide des résultats de recherche et leur intégration dans la politique gouvernementale. CONSéQUENCES: L’approche de la TCM est un moyen d’obtenir rapidement des conseils scientifiques à l’extérieur du gouvernement et des organismes de santé publique. Au-delà de sa rapidité, cette approche offre une grande souplesse, car des experts de différents organismes peuvent être ajoutés au besoin. Elle montre aussi que les universités et les établissements de recherche ont un rôle à jouer dans les situations de crise, et qu’il est possible de mobiliser leurs compétences pour éclairer les politiques tout en respectant la liberté et la confidentialité des milieux de la recherche et de l’enseignement.
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  • 文章类型: Journal Article
    分子和合成生物学的进步使昆虫的基因驱动工程能够控制病媒/病虫害。可以设计工程化基因驱动器(使其自身遗传偏向)以抑制杂交目标种群或用新的基因型修饰它们。根据工程化的基因驱动系统,理论上,感兴趣的基因改造可以在目标人群中传播并无限期地持续下去,或限制其传播或持久性。尽管有关工程基因驱动器及其在昆虫中的应用的研究正在快速发展,技术发展需要几年时间才能转向实际应用,以便有意释放到环境中。一些基因驱动改性昆虫(GDMIs)已经在实验室进行了实验测试,但尚未在小规模密闭野外试验或开放释放试验中进行评估.人们担心,在环境中故意释放GDMIs可能会产生不可逆转和意想不到的后果。作为一项主动措施,欧盟委员会已要求欧洲食品安全局(EFSA)审查其先前发布的转基因动物风险评估指南(EFSA,2012年和2013年),包括昆虫(GMI),对于GDI来说是足够的,主要是疾病媒介,农业害虫和入侵物种,故意释放到环境中。根据这项任务,EFSA未被要求制定GDI风险评估指南。在这个科学观点中,转基因生物(GMO)小组得出结论,EFSA的指导方针是足够的,但不足以进行分子表征(MC),GDI的环境风险评估(ERA)和上市后环境监测(PMEM)。而MC,GDMIs的ERA和PMEM可以建立在不包含工程基因驱动的GMI的现有风险评估框架上,在特定领域需要对GDI进行进一步指导。
    Advances in molecular and synthetic biology are enabling the engineering of gene drives in insects for disease vector/pest control. Engineered gene drives (that bias their own inheritance) can be designed either to suppress interbreeding target populations or modify them with a new genotype. Depending on the engineered gene drive system, theoretically, a genetic modification of interest could spread through target populations and persist indefinitely, or be restricted in its spread or persistence. While research on engineered gene drives and their applications in insects is advancing at a fast pace, it will take several years for technological developments to move to practical applications for deliberate release into the environment. Some gene drive modified insects (GDMIs) have been tested experimentally in the laboratory, but none has been assessed in small-scale confined field trials or in open release trials as yet. There is concern that the deliberate release of GDMIs in the environment may have possible irreversible and unintended consequences. As a proactive measure, the European Food Safety Authority (EFSA) has been requested by the European Commission to review whether its previously published guidelines for the risk assessment of genetically modified animals (EFSA, 2012 and 2013), including insects (GMIs), are adequate and sufficient for GDMIs, primarily disease vectors, agricultural pests and invasive species, for deliberate release into the environment. Under this mandate, EFSA was not requested to develop risk assessment guidelines for GDMIs. In this Scientific Opinion, the Panel on Genetically Modified Organisms (GMO) concludes that EFSA\'s guidelines are adequate, but insufficient for the molecular characterisation (MC), environmental risk assessment (ERA) and post-market environmental monitoring (PMEM) of GDMIs. While the MC,ERA and PMEM of GDMIs can build on the existing risk assessment framework for GMIs that do not contain engineered gene drives, there are specific areas where further guidance is needed for GDMIs.
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  • 文章类型: Consensus Development Conference
    在过去的十年中,HPV建模的激烈研究活动促使开发了针对一般建模的其他指南。需要一个特定的框架来解决不同的政策问题和HPV建模的独特复杂性。HPV-FRAME是一项旨在为流行病学和经济HPV模型制定共识声明和基于质量的框架的倡议。它的发展涉及一个既定的过程。报告标准已根据反映HPV和癌症预防中不同政策问题的七个领域进行了构建,并按与人群或评估的相关性进行了分类。与人口相关的领域是:1)青春期前和年轻青少年中的HPV疫苗接种;2)老年人中的HPV疫苗接种;3)对男男性行为者的针对性疫苗接种;4)对艾滋病毒感染者的考虑;5)对低收入和中等收入国家的考虑。适用于特定评估的其他考虑因素是:6)子宫颈筛查或综合子宫颈筛查和HPV疫苗接种方法,以及7)替代疫苗类型和替代给药时间表。HPV-FRAME旨在根据明确的框架促进模型的开发,更好地使目标受众了解模型在特定政策问题上的优势和劣势,并最终提高模型对知情决策的贡献。
    Intense research activity in HPV modelling over this decade has prompted the development of additional guidelines to those for general modelling. A specific framework is required to address different policy questions and unique complexities of HPV modelling. HPV-FRAME is an initiative to develop a consensus statement and quality-based framework for epidemiologic and economic HPV models. Its development involved an established process. Reporting standards have been structured according to seven domains reflecting distinct policy questions in HPV and cancer prevention and categorised by relevance to a population or evaluation. Population-relevant domains are: 1) HPV vaccination in pre-adolescent and young adolescent individuals; 2) HPV vaccination in older individuals; 3) targeted vaccination in men who have sex with men; 4) considerations for individuals living with HIV and 5) considerations for low- and middle-income countries. Additional considerations applicable to specific evaluations are: 6) cervical screening or integrated cervical screening and HPV vaccination approaches and 7) alternative vaccine types and alternative dosing schedules. HPV-FRAME aims to promote the development of models in accordance with an explicit framework, to better enable target audiences to understand a model\'s strength and weaknesses in relation to a specific policy question and ultimately improve the model\'s contribution to informed decision-making.
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  • 文章类型: Journal Article
    The origin of population-scale coordination has puzzled philosophers and scientists for centuries. Recently, game theory, evolutionary approaches and complex systems science have provided quantitative insights on the mechanisms of social consensus. However, the literature is vast and widely scattered across fields, making it hard for the single researcher to navigate it. This short review aims to provide a compact overview of the main dimensions over which the debate has unfolded and to discuss some representative examples. It focuses on those situations in which consensus emerges \'spontaneously\' in the absence of centralized institutions and covers topics that include the macroscopic consequences of the different microscopic rules of behavioural contagion, the role of social networks and the mechanisms that prevent the formation of a consensus or alter it after it has emerged. Special attention is devoted to the recent wave of experiments on the emergence of consensus in social systems.
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