modelling

建模
  • 文章类型: Journal Article
    背景:尼日利亚是报告诊断和估计患有结核病(TB)的人之间差距最大的五个国家之一。为了弥合这个差距,需要创新的方法来识别结核病传播高风险的地理区域和有针对性的主动病例发现(ACF)干预措施.利用社区级别的数据以及精细的社会人口统计上下文信息可以揭开可能被错过的本地热点。这项工作评估了这种方法是否有助于覆盖未诊断结核病数量更多的社区。方法:对尼日利亚西南四个州的ACF干预计划产生的数据进行了回顾性分析。病房(尼日利亚最小的行政级别)被进一步细分为较小的人口集群。ACF位点及其各自的TB筛选输出被映射到这些群体集群。然后将这些数据与开源高分辨率上下文数据相结合,以训练贝叶斯推理模型。该模型预测了社区水平(人口集群水平)的结核病阳性率,这些数据在定制的地理位置上可视化,供当地团队使用,以识别结核病传播高风险的社区并计划ACF干预措施。将在模型预测的热点处观察到的TB阳性产量(比例)与在基于汇总通知数据识别的其他站点处获得的产量进行比较。结果:模型预测具有高TB阳性率的群体集群的产量比所有四个州的其他位置的产量高至少1.75倍(p值<0.001)。结论:社区层面的贝叶斯预测模型有可能引导ACF实施者到高结核病阳性地区,以在社区中发现未诊断的结核病。从而提高干预的效率。
    Background: Nigeria is among the top five countries that have the highest gap between people reported as diagnosed and estimated to have developed tuberculosis (TB). To bridge this gap, there is a need for innovative approaches to identify geographical areas at high risk of TB transmission and targeted active case finding (ACF) interventions. Leveraging community-level data together with granular sociodemographic contextual information can unmask local hotspots that could be otherwise missed. This work evaluated whether this approach helps to reach communities with higher numbers of undiagnosed TB. Methodology: A retrospective analysis of the data generated from an ACF intervention program in four southwestern states in Nigeria was conducted. Wards (the smallest administrative level in Nigeria) were further subdivided into smaller population clusters. ACF sites and their respective TB screening outputs were mapped to these population clusters. This data were then combined with open-source high-resolution contextual data to train a Bayesian inference model. The model predicted TB positivity rates on the community level (population cluster level), and these were visualised on a customised geoportal for use by the local teams to identify communities at high risk of TB transmission and plan ACF interventions. The TB positivity yield (proportion) observed at model-predicted hotspots was compared with the yield obtained at other sites identified based on aggregated notification data. Results: The yield in population clusters that were predicted to have high TB positivity rates by the model was at least 1.75 times higher (p-value < 0.001) than the yield in other locations in all four states. Conclusions: The community-level Bayesian predictive model has the potential to guide ACF implementers to high-TB-positivity areas for finding undiagnosed TB in the communities, thus improving the efficiency of interventions.
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  • 文章类型: Journal Article
    胡须秃鹰(Gypaetusbarbatus)是一种濒危物种,具有专门的食骨(骨)饮食。我们估计了这种秃鹰在阿拉贡比利牛斯山脉的生存和生产力,在欧洲发现了该物种的主要种群。我们使用了一个涵盖33年(1987-2020年)的数据库。为了估计生存的可能性,我们用贝叶斯方法使用Cormack-Jolly-Seber模型。我们的模型估计青少年的存活率为0.90±0.08,亚成人为0.95±0.04,成人为0.92±0.05。在研究期间,成年人和亚成年人的生存概率增加,而青少年则没有。相比之下,同期生产率下降。我们的研究提供了有关对该物种非常重要的两个人口统计学参数的状态的最新信息,并使我们能够确定最脆弱的年龄段,并计划保护行动以改善该物种在该地区的状况。重新引入项目的标本。估计的生存值表明,在根据物种的使用情况计划这些喂食点时,应更加谨慎。
    The bearded vulture (Gypaetus barbatus) is an endangered species with a specialist osteophagous (bone) diet. We estimated the survival and productivity of this vulture in the Aragonese Pyrenees, where the main population of the species in Europe is found. We used a database covering a period of 33 years (1987-2020). To estimate the probability of survival, we used Cormack-Jolly-Seber models with a Bayesian approach. Our models estimated a survival rate of 0.90 ± 0.08 in juveniles, 0.95 ± 0.04 in subadults and 0.92 ± 0.05 in adults. The survival probability increased over the study period in adults and subadults but not in juveniles. By contrast, productivity decreased over the same period. Our study provides updated information on the status of two demographic parameters of great importance to the species and allows us to identify the most vulnerable age classes and to plan conservation actions to improve the situation of the species in a territory that is a donor of specimens for reintroduction projects. The estimated survival values suggest that more caution should be exercised when planning these feeding points according to the use the species makes of them.
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  • 文章类型: Journal Article
    背景COVID-19是本世纪最严重的流行病,导致经济、社会,和教育中断。实习培训也不例外,由于培训限制,延迟了住院医师的成长和毕业。我们试图利用模拟模型来预测由于COVID-19和未来类似性质的大流行而重复和长时间的运动限制对未来队列的影响。方法进行了一项德尔菲研究,以确定受COVID-19影响的国际研究生医学教育认证委员会(ACGME-I)培训变量。从2018年到2021年,对这些变量的定量居民数据集进行了整理和分析。使用Vensim®软件(VentanaSystems,Inc.,哈佛,MA),使用历史居民数据和大流行进展延迟来创建一个新的模拟模型来预测未来的进展延迟.各种持续时间的延迟也被编程到软件中,以模拟影响居民进展的不同严重程度的限制。结果使用具有模拟不同大流行长度的情景的模型,我们发现,居民在每个认可年份的平均延误估计范围从第二年居民增加一个月到第四年居民超过三个月。为期一年的行动限制将需要长达六年的时间,该计划才能恢复到大流行前的平衡。结论系统动态建模可用于预测大流行期间住院医师培训计划的延迟。因此,可以预测对劳动力的影响,允许居留计划制定缓解措施,以避免进展延迟。
    Background COVID-19 has been the worst pandemic of this century, resulting in economic, social, and educational disruptions. Residency training is no exception, with training restrictions delaying the progression and graduation of residents. We sought to utilize simulation modelling to predict the impact on future cohorts in the event of repeated and prolonged movement restrictions due to COVID-19 and future pandemics of a similar nature. Method A Delphi study was conducted to determine key Accreditation Council for Graduate Medical Education-International (ACGME-I) training variables affected by COVID-19. Quantitative resident datasets on these variables were collated and analysed from 2018 to 2021. Using the Vensim® software (Ventana Systems, Inc., Harvard, MA), historical resident data and pandemic progression delays were used to create a novel simulation model to predict future progression delay. Various durations of delay were also programmed into the software to simulate restrictions of varying severity that would impact resident progression. Results Using the model with scenarios simulating varying pandemic length, we found that the estimated average delay for residents in each accredited year ranged from an increase of one month for year 2 residents to more than three months for year 4 residents. Movement restrictions lasting a year would require up to six years before the program returned to a pre-pandemic equilibrium. Conclusion Systems dynamic modelling can be used to predict delays in residency training programs during a pandemic. The impact on the workforce can thus be projected, allowing residency programs to institute mitigating measures to avoid progression delay.
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  • 文章类型: Journal Article
    这份简短的交流反映了多个COVID-19建模和数据分析小组的挑战和建议,这些小组提供了定量证据,以支持SARS-CoV-2大流行期间瑞士和德国的卫生政策讨论。将需要加强传染病紧急情况以外的能力,以使环境能够及时,高效,和数据驱动的响应,以支持未来任何传染病紧急情况下的决策。这将需要1)大量训练有素的专家,他们不断推进最先进的方法论工具,2)在科学家和决策者之间建立结构联络,3)数据共享框架的建立和管理。
    This short communication reflects upon the challenges and recommendations of multiple COVID-19 modelling and data analytic groups that provided quantitative evidence to support health policy discussions in Switzerland and Germany during the SARS-CoV-2 pandemic. Capacity strengthening outside infectious disease emergencies will be required to enable an environment for a timely, efficient, and data-driven response to support decisions during any future infectious disease emergency. This will require 1) a critical mass of trained experts who continuously advance state-of-the-art methodological tools, 2) the establishment of structural liaisons amongst scientists and decision-makers, and 3) the foundation and management of data-sharing frameworks.
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  • 文章类型: Journal Article
    保护和增加农业用地中的线性景观要素(LLE)被认为是向生物多样性更高的农业系统过渡的可能解决方案。然而,优化LLE保护区的空间配置具有挑战性,特别是考虑到粮食生产对土地的需求。系统保护规划(SCP)可以应对这一挑战,通过优先考虑具有成本效益的保护区。我们使用SCP方法观察了荷兰北布拉班特省的LLE网络,确定优化物种保护之间可能的权衡,生态系统服务(ES)的成本和货币价值。为此,我们定义了两种情况。一种方案侧重于以最低成本实现物种保护目标,另一个侧重于实现目标,同时最大化ES提供的利益。对于每个场景,我们进一步开发了两种土地管理方案,即土地共享和土地节约。对于每个解决方案,我们通过计算实施成本来测试它们的成本效益,ES提供的经济效益,和成本/效益比。首先,我们的情景分析表明,ES提供的经济利益总是超过实施成本。第二,它表明,在SCP(最大化ES方案)中包括ES作为共同利益会产生更具成本效益的保护解决方案。第三,土地共享和土地节约都是实现保护目标的可能成本效益高的方法。我们的结果在空间上是明确的,并确定了保护选定物种的关键栖息地,代表当前未受保护的LLE网络的12-20%。我们的发现展示了保护物种和LLE的净经济效益,因此代表了生物多样性保护的另一个原因。
    Protecting and increasing linear landscape elements (LLEs) in agricultural lands is regarded as a possible solution for a transition to a more biodiverse agricultural system. However, optimizing the spatial configuration of LLEs protected areas is challenging, especially given the demand for land for food production. Systematic Conservation Planning (SCP) can address this challenge, by prioritizing cost-efficient protection areas. We used a SCP approach to look at the LLEs network in the Province of Noord-Brabant in the Netherlands, identifying the possible trade-off between optimizing species conservation, costs and the monetary values of ecosystem services (ES). For this we defined two scenarios. One scenario focuses on achieving species conservation targets at the minimum cost, and the other focuses on achieving targets while maximizing the benefits provided by ES. For each scenario, we further developed two land-management options, namely land-sharing and land-sparing. For each solution, we tested their cost-effectiveness by calculating implementation costs, economic benefits provided by ES, and cost/benefit ratios. First, our scenario analysis indicates that the economic benefits provided by ES always outweigh the implementation costs. Second, it shows that including ES as co-benefits in SCP (Maximize ES Scenario) yields more cost-efficient conservation solutions. Third, both land-sharing and land-sparing are possible cost-efficient approaches to achieve conservation targets. Our results are spatially explicit and identify crucial habitat areas for the conservation of the selected species, which represent 12-20% of the current unprotected network of LLEs. Our findings showcase net economic benefit of conserving species and LLEs, thus representing an additional reason for biodiversity conservation.
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  • 文章类型: Journal Article
    食品供应链不断受到食品安全隐患的挑战。在这种食品安全威胁或冲击之后,供应链在合理时间内提供安全食品的能力可以通过以食品安全为指标的弹性概念进行调查。然后将弹性定义为由于冲击而导致的食品安全性能偏差,并考虑冲击的严重程度以及完全恢复或达到新平衡的时间。这项研究开发了一个随机模拟模型来评估荷兰猪肉供应链对饲料中二恶英污染的抵御能力。在几种监测策略之间比较了供应链的弹性以及与污染相关的潜在成本,目的是确定二恶英监测的最佳控制点。模型结果表明,在猪肉供应链上多个控制点采集和分析样本,特别是在饲料厂和脂肪熔化设施,导致了最高的弹性和冲击后最低的成本。公共和私人决策者可以使用此模型和这些结果来就控制猪肉供应链中二恶英的监测策略做出主动和明智的决策,从而实现对二恶英危机的最佳抵御能力。
    Food supply chains are constantly challenged by food safety hazards entering the chain. The ability of the supply chain to provide safe food within a reasonable time after such a food safety threat or shock can be investigated with the concept of resilience using food safety as an indicator. Resilience is then defined as the food safety performance deviation due to the shock and takes both the severity of the shock as well as the time to fully recover or reach a new equilibrium into account. This study developed a stochastic simulation model to evaluate the resilience of the Dutch pork supply chain to dioxin contamination in the feed. The resilience of the supply chain as well as the potential costs associated with the contamination are compared between several monitoring strategies with the aim to determine the optimal control points for dioxin monitoring. Model results show that collecting and analyzing samples at more than one control point along the pork supply chain, in particular at feed mills and fat melting facilities, resulted in the highest resilience and the lowest costs after a shock. This model and these results can be used by public and private decision makers to make proactive and informed decisions on the monitoring strategies to control dioxins in the pork supply chain that result in optimal resilience to a dioxin crises.
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  • 文章类型: Journal Article
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  • 文章类型: Journal Article
    诸如NOx的有害污染物的路边浓度在空间和时间上都是高度可变的。在评估行人和骑车人暴露时很少考虑这一点。我们旨在以高分辨率充分描述沿道路行驶的行人和骑自行车者的暴露的时空变化。与仅高空间分辨率相比,我们评估了高时空分辨率的附加值。我们还将高分辨率车辆排放建模与使用恒定体积源进行比较。我们强调峰值曝光的条件,并讨论对健康影响评估的影响。使用大涡模拟代码Fluidity,我们在复杂的现实世界街道几何形状中,沿350m的路段以2m和1s的分辨率模拟NOx浓度,包括十字路口和公共汽车站。然后,我们模拟不同路线和出发时间的行人和骑自行车的旅程。对于高时空方法,行人经历的1s浓度的标准偏差(50.9μg。m-3)几乎是高空间预测的三倍(17.5μg。m-3)或恒定体积源(17.6μg。m-3)方法。这种暴露的特点是低浓度,持续时间短,峰值曝光提高平均曝光,其他两种方法无法捕获。我们还发现,骑自行车的人在道路上的平均暴露量(31.8μg。m-3)明显大于路边道路上的骑车人(25.6μg。m-3)和人行道上的行人(17.6μg。m-3)。我们得出的结论是,忽略在呼吸时间尺度上经历的高分辨率时间空气污染变化会导致行人和骑自行车者暴露的错误表征。因此也可能造成伤害。高分辨率方法揭示了峰值,因此意味着暴露,可以通过避免公共汽车站和路口等超局部热点来有意义地减少。
    Roadside concentrations of harmful pollutants such as NOx are highly variable in both space and time. This is rarely considered when assessing pedestrian and cyclist exposures. We aim to fully describe the spatio-temporal variability of exposures of pedestrians and cyclists travelling along a road at high resolution. We evaluate the value added of high spatio-temporal resolution compared to high spatial resolution only. We also compare high resolution vehicle emissions modelling to using a constant volume source. We highlight conditions of peak exposures, and discuss implications for health impact assessments. Using the large eddy simulation code Fluidity we simulate NOx concentrations at a resolution of 2 m and 1 s along a 350 m road segment in a complex real-world street geometry including an intersection and bus stops. We then simulate pedestrian and cyclist journeys for different routes and departure times. For the high spatio-temporal method, the standard deviation in 1 s concentration experienced by pedestrians (50.9 μg.m-3) is nearly three times greater than that predicted by the high-spatial only (17.5 μg.m-3) or constant volume source (17.6 μg.m-3) methods. This exposure is characterised by low concentrations punctuated by short duration, peak exposures which elevate the mean exposure and are not captured by the other two methods. We also find that the mean exposure of cyclists on the road (31.8 μg.m-3) is significantly greater than that of cyclists on a roadside path (25.6 μg.m-3) and that of pedestrians on a sidewalk (17.6 μg.m-3). We conclude that ignoring high resolution temporal air pollution variability experienced at the breathing time scale can lead to a mischaracterization of pedestrian and cyclist exposures, and therefore also potentially the harm caused. High resolution methods reveal that peaks, and hence mean exposures, can be meaningfully reduced by avoiding hyper-local hotspots such as bus stops and junctions.
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  • 文章类型: Journal Article
    海上活动对港口地区有不同的环境影响,尤其是空气质量,后COVID-19邮轮旅游市场的复苏和增长潜力正在给不断扩张的港口城市带来新的环境问题。这项研究提出了一种经验和建模方法,用于评估游轮对拉巴斯(墨西哥)市NO2和SO2空气质量的影响。EPA排放因子和与WRF耦合的AERMOD建模系统用于对分散体进行建模,而使用2018年两天的空气质量街道级移动监测数据,并使用径向基函数插值器进行处理。使用两个数据集在交叉点水平上估计了局部差分Moran指数,并进行了协同定位聚类分析,以解决空间恒定性并确定污染水平。模拟结果表明,游轮对空气质量的影响,NO2的最大值为13.66μg/m3,SO2的最大值为15.71μg/m3,而NOx的背景浓度为8.80,SOx的背景浓度为0.05(μg/m3)通过分析不受港口污染影响的交叉路口的LISA指数值来发现。本文为使用混合方法作为在完全缺乏环境数据的情况下研究多源污染物对空气质量影响的方法提供了见解。
    Maritime activity has diverse environmental consequences impacts in port areas, especially for air quality, and the post-COVID-19 cruise tourism market\'s potential to recover and grow is causing new environmental concerns in expanding port cities. This research proposes an empirical and modelling approach for the evaluation of cruise ships\' influence on air quality concerning NO2 and SO2 in the city of La Paz (Mexico) using indirect measurements. EPA emission factors and the AERMOD modelling system coupled to WRF were used to model dispersions, while street-level mobile monitoring data of air quality from two days of 2018 were used and processed using a radial base function interpolator. The local differential Moran\'s Index was estimated at the intersection level using both datasets and a co-location clustering analysis was performed to address spatial constancy and to identify the pollution levels. The modelled results showed that cruise ships\' impact on air quality had maximum values of 13.66 μg/m3 for NO2 and 15.71 μg/m3 for SO2, while background concentrations of 8.80 for NOx and 0.05 for SOx (μg/m3) were found by analysing the LISA index values for intersections not influenced by port pollution. This paper brings insights to the use of hybrid methodologies as an approach to studying the influence of multiple-source pollutants on air quality in contexts totally devoid of environmental data.
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  • 文章类型: Journal Article
    生物数学模型定量描述了人类对环境和操作压力源的生理反应,并已用于计划和实时预防冷损伤。可以从军事战术角度应用这些相同的模型,以获得对对手士兵健康状况的宝贵见解。本文介绍了一个使用开源信息预测入侵乌克兰的俄罗斯士兵的生理状态的用例。2022年3月,媒体报道,入侵乌克兰的车队中的俄罗斯士兵面临严重的体温过低风险,并预测这些士兵将在几天内“冻死”,因为气温下降(降至-20°C)。使用现有的陆军模型,服装数据和开源情报,在数小时内进行建模和分析,以定量评估条件并提供基于科学的预测。这些预测预测了暴露的皮肤,脚趾和脚的冻伤风险显着增加,体温过低的风险很低(可以忽略不计)。几天后,媒体证实了这些预测,据报道,这些俄罗斯军队因脚部冻伤而撤离的人数急剧上升。这证明了现有的数学生理学今天可以做什么,以及传统上关注健康风险的模型如何用于战术情报。
    Biomathematical models quantitatively describe human physiological responses to environmental and operational stressors and have been used for planning and real-time prevention of cold injury. These same models can be applied from a military tactical perspective to gain valuable insights into the health status of opponent soldiers. This paper describes a use case for predicting physiological status of Russian soldiers invading Ukraine using open-source information. In March 2022, media outlets reported Russian soldiers in a stalled convoy invading Ukraine were at serious risk of hypothermia and predicted these soldiers would be \"freezing to death\" within days because of declining temperatures (down to -20°C). Using existing Army models, clothing data and open-source intelligence, modelling and analyses were conducted within hours to quantitatively assess the conditions and provide science-based predictions. These predictions projected a significant increase in risks of frostbite for exposed skin and toes and feet, with a very low (negligible) risk of hypothermia. Several days later, media outlets confirmed these predictions, reporting a steep rise in evacuations for foot frostbite injuries in these Russian forces. This demonstrated what can be done today with the existing mathematical physiology and how models traditionally focused on health risk can be used for tactical intelligence.
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