Purpose:The coronavirus disease-2019(COVID-19)pandemic in the United States led to nationwide stay-at-home orders and school closures.Declines in energy expenditure resulting from canceled physical education classes a...Purpose:The coronavirus disease-2019(COVID-19)pandemic in the United States led to nationwide stay-at-home orders and school closures.Declines in energy expenditure resulting from canceled physical education classes and reduced physical activity may elevate childhood obesity risk.This study estimated the impact of COVID-19 on childhood obesity.Methods:A microsimulation model simulated the trajectory of a nationally representative kindergarten cohort’s body mass index z-scores and childhood obesity prevalence from April 2020 to March 2021 under the control scenario without COVID-19 and under the 4 alternative scenarios with COVID-19—Scenario 1:2-month nationwide school closure in April and May 2020;Scenario 2:Scenario 1 followed by a 10%reduction in daily physical activity in the summer from June to August;Scenario 3:Scenario 2 followed by 2-month school closure in September and October;and Scenario 4:Scenario 3 followed by an additional 2-month school closure in November and December.Results:Relative to the control scenario without COVID-19,Scenarios 1,2,3,and 4 were associated with an increase in the mean body mass index z-scores by 0.056(95%confidence interval(95%CI):0.0550.056),0.084(95%CI:0.0840.085),0.141(95%CI:0.1400.142),and 0.198(95%CI:0.1970.199),respectively,and an increase in childhood obesity prevalence by 0.640(95%CI:0.5150.765),0.972(95%CI:0.8191.126),1.676(95%CI:1.4751.877),and 2.373(95%CI:2.1352.612)percentage points,respectively.Compared to girls and non-Hispanic whites and Asians,the impact of COVID-19 on childhood obesity was modestly larger among boys and non-Hispanic blacks and Hispanics,respectively.Conclusion:Public health interventions are urgently called to promote an active lifestyle and engagement in physical activity among children to mitigate the adverse impact of COVID-19 on unhealthy weight gains and childhood obesity.展开更多
AIM: To hypothesize that the product of calculated Model for End-Stage Liver Disease score excluding exception points and donor age(D-MELD) risk capping ± Rule 14 could improve post liver transplant and overall s...AIM: To hypothesize that the product of calculated Model for End-Stage Liver Disease score excluding exception points and donor age(D-MELD) risk capping ± Rule 14 could improve post liver transplant and overall survival after listing.METHODS: Probabilities derived from the United Network for Organ Sharing database between 2002 and 2004 were used to simulate potential outcomes for all patients listed for transplantation. The Markov simula-tion was then modified by screening matches using a 1200 or 1600 D-MELD risk cap ± allowing transplants for Model for End-Stage Liver Disease(MELD) ≤ 14(Rule 14). The differential impact of the rule changes was assessed.RESULTS: The Markov simulation accurately reproduced overall and post transplant survival. A 1200 D-MELD risk cap improved post-transplant survival. Both the 1200 and 1600 risk caps improved overall survival for waitlisted patients. The addition of Rule 14 further improved post transplant and overall survival by redistribution of donor livers to recipients in higher MELD subgroups. The mechanism for improved overall and post-transplant survival after listing was due to shifting a larger percentage of transplants to the moderate MELD score subgroup(MELD 15-29) while also ensuring that high MELD recipients have livers of high quality to achieve excellent post transplant survival.CONCLUSION: A 1200 D-MELD risk cap + Rule 14 provided the greatest overall benefit primarily by focusing liver transplantation towards the moderate MELD recipient.展开更多
High quality infrastructure is crucial to economic success and the sustainability of society.Infrastructures for services,such as transport,energy,and water supply,also have long lead times,and therefore require effec...High quality infrastructure is crucial to economic success and the sustainability of society.Infrastructures for services,such as transport,energy,and water supply,also have long lead times,and therefore require effective long-term planning.In this paper,we report on work undertaken as part of the UK Infrastructure Transitions Research Consortium to construct long-term models of demographic change which can help to inform infrastructure planning for transport,energy,and water as well as IT and waste.A set of demographic microsimulation models(MSM),which are spatially disaggregate to the geography of UK Local Authorities,provides a high level of detail for understanding the drivers of changing patterns of demand.However,although robust forecasting models are required to support projections based on the notion of‘predict-and-provide,’the potential for behavioral adaptation is also an important consideration in this context.In this paper,we therefore establish a framework for linkage of a MSM of household composition,with behavior relating to the consumption of energy.We will investigate variations in household energy consumption within and between different household groups.An appropriate range of household types will be defined through the application of decision trees to consumption data from a detailed survey produced by the UK Department of Energy and Climate Change.From this,analysis conclusions will be drawn about the impact of changing demographics at both household and individual level,and about the potential effect of behavioral adjustments for different household groups.展开更多
This research assessed the impact of efficiently expanding the biking network in Atlanta,Georgia,using dedicated lanes for bicycles.A total of three different conditions,i.e.,exist-ing,proposed(by the authors),and alt...This research assessed the impact of efficiently expanding the biking network in Atlanta,Georgia,using dedicated lanes for bicycles.A total of three different conditions,i.e.,exist-ing,proposed(by the authors),and alternative(suggested by the City of Atlanta)condi-tions,were modeled to see the effectiveness of bike infrastructure design improvement and expansion.Trajectory data collected from the VISSIM simulation model were used in the Federal Highway Administration(FHWA)’s surrogate safety assessment model(SSAM)to analyze the safety effect on the bike infrastructure improvement and expansion.Based on the results,both the proposed and alternative conditions resulted in safer travel through the network during the peak hour period without any apparent deterioration in delays.For instance,compared to the existing condition,the average stop delays decreased from 190 s to 164 s for the proposed and the alternative conditions.These findings showed that the introduction of bicycle lanes and narrower lanes for automobiles may not adversely affect the peak hour congestion.Also,fewer conflicts were observed in the sim-ulated network of proposed and alternative conditions compared to existing conditions.Conflicts involving bicyclists were also reduced since the bicyclists can use their own lanes and do not have to interact with automobile traffic in the sharrows.展开更多
Traffic safety and performance measures such as crash risk and queue lengths or travel times are influenced by several important factors including those related to environment,human,and roadway design,especially at in...Traffic safety and performance measures such as crash risk and queue lengths or travel times are influenced by several important factors including those related to environment,human,and roadway design,especially at intersections.Previous research has studied different aspects related to these factors,yet these characteristics are not fully investigated with a focus on age and experience of drivers.In this paper,we investigate this issue by using a two-phase approach via a case study application on a critical T-intersection in the City of Tallahassee,Florida.The first phase includes a scenario-based microsimulation analysis through the use of a microscopic simulation software,namely VISSIM,to illustrate the variations in traffic performance measures with respect to driver compositions of different age groups in the traffic stream.A variety of scenarios is created where the driving characteristics are provided as inputs to these scenarios in terms of decision making and risk taking.This is also supported by a sensitivity analysis conducted based on the driver composition in the traffic.The second phase includes the analysis of microsimulation outputs via a tool developed by Federal Highway Administration tool,namely the Surrogate Safety Assessment Model(SSAM),in order to determine the traffic conflicts that occur in each scenario.These conflicts are also compared with real-life crash data for validation purposes.Results show that(a) the differences in risk perception that affect driving behavior might be significant in influencing traffic safety and performance measures,and(b) the proposed approach is considerably successful in simulating the actual crash conflict points.展开更多
Roundabouts are very useful when flows are balanced but can have operational challenges when flows increase.Most roundabouts on arterial roadways in Ghana experience recurring congestion during peak traffic.The four r...Roundabouts are very useful when flows are balanced but can have operational challenges when flows increase.Most roundabouts on arterial roadways in Ghana experience recurring congestion during peak traffic.The four roundabouts between Ejisu Municipality and Asokwa Municipality on the N6 highway are typical of the situation found on arterials countrywide.They experience recurring long queues and delays during the peak hours and over-representation of truck rollover accidents.In Ghana,historically,most roundabouts with capacity problems have been developed into interchanges at very high cost without consideration of other effective at-grade configurations.When roundabouts are signalized,various configurations can be explored to enhance capacity while preserving the safety benefits.Using simulation techniques,various configurations and design options were tested for their effectiveness at two of the roundabouts,located at KNUST police station and Ejisu,with similar demand and high left turning volumes.The objectives of this study were to a)evaluate the performance of the selected roundabouts on the corridor;b)explore alternative intersection configurations to improve capacity and delay.Using video data collection techniques,2-h time stamped footages of AM and PM peak traffic flows were captured for two days.Geometric design parameters of the existing roundabouts,queue lengths,travel times,and approach flows were also captured.VISSIM models of the selected roundabouts were developed and calibrated for the baseline conditions.Signalized unconventional roundabout configuration,with a phase for major road through traffic were simulated and assessed for capacity,delay and queue length.The results showed that signalized roundabout intersections effectively increased capacity by as much as 50%in some cases,reduced delay and queue length significantly,and maintained the benefits of roundabouts including safety.The performance could be further enhanced by introducing separate left turn phases to reduce conflicts or through a right turn U-turn(RTUT)concept.展开更多
Chinese migrant workers are very exposed to the shocks caused by the COVID-19 pandemic.Falling remittances adversely affect their families who rely on remittance incomes.The impacts of COVID-19 on migrants and remitta...Chinese migrant workers are very exposed to the shocks caused by the COVID-19 pandemic.Falling remittances adversely affect their families who rely on remittance incomes.The impacts of COVID-19 on migrants and remittance-receiving households are assessed using a nationally representative household dataset and a microsimulation model.We found about 70 percent of migrant workers lost part of their wage income during the pandemic lockdown period and rural migrants working in small and medium enterprises were affected the most.This led to about 50 percent of remittance-receiving households being affected adversely by falling remittances,and the average decline in such income was more than 45 percent.Nearly 13 percent of pre-pandemic nonpoor remittance-receiving households could fall into poverty,raising the poverty rate among remittancereceiving households by 4 percentage points.Many households that were poor prior to the pandemic became more impoverished.The results indicate that social protection programs targeting vulnerable migrants and their families at home are important.展开更多
Background:The effectiveness of lung cancer screening with low-dose computed tomography(LDCT)has been established.The current study evaluates the cost-effectiveness of lung cancer screening with LDCT in a general popu...Background:The effectiveness of lung cancer screening with low-dose computed tomography(LDCT)has been established.The current study evaluates the cost-effectiveness of lung cancer screening with LDCT in a general population in China.Methods:A previously validated micro-simulation model was used to simulate a cohort of men and women on a lifetime horizon in the presence and absence of LDCT screening.The modeling data were collected from numerous national and international sources.Simulated screening scenarios included different combinations of screening intervals and start and stop ages.Additional costs(valued in Chinese Yuan,CNY;1 USD=6.8976 CNY,1 EUR=7.8755 CNY in 2020),life-years gained(LYG)and mortality reduction due to screening were also determined.The costs and life-years were discounted by 3%.All results were scaled to 1,000 individuals.The average cost-effectiveness ratio(ACER)was calculated.A willingness-to-pay threshold of CNY 217.3k/LYG was considered.A healthcare system perspective was adopted.Results:Compared to no screening,lung cancer screening by LDCT in a general Chinese population yielded 21.0-36.7 LYG in men and 9.2-16.6 LYG in women across the scenarios.For men,biennial LDCT screening yielded an ACER of CNY 171.4k-306.3k/LYG relative to no screening.Biennial screening performed between 55 and 75 years of age was optimal at the defined threshold;it resulted in CNY 174.6k/LYG and a lung cancer mortality reduction of 9.1%,and this scenario had a 75%probability of being cost-effective.For women,the ACER ranged from CNY 364.2k to 1193.3k/LYG.Conclusions:In China,lung cancer screening with LDCT in the general population including never smokers could be cost-effective for men with 75%probability,but not for women.The optimal strategy for men would be performing biennial screening between 55 and 75 years of age.展开更多
Introduction:Myopia has emerged as a major public health challenge affecting the visual health of children and adolescents in China.While evidence confirms the effectiveness of outdoor activity in preventing myopia,co...Introduction:Myopia has emerged as a major public health challenge affecting the visual health of children and adolescents in China.While evidence confirms the effectiveness of outdoor activity in preventing myopia,comprehensive economic analyses of its role in mitigating myopia-related diseases remain limited.Methods:This study employed a microsimulation model to evaluate the cost-effectiveness of increasing outdoor activity across different educational stages—primary,middle,and high school—for myopia prevention in China.The model simulated myopia progression among individuals aged 6 to 18 years,with the intervention defined as an additional 40 minutes of daily outdoor activity.Outcomes measured included changes in myopia prevalence,quality-adjusted life years(QALYs),and associated medical costs.Results:All intervention scenarios proved costeffective,except for those targeting only the high school stage.Interventions focused on primary schools and combined primary–middle school stages not only improved health outcomes but also reduced medical costs.While the all-stages intervention yielded the greatest health benefits,its higher implementation costs make it more suitable for regions with greater resources.Conclusion:These findings highlight the critical importance of early intervention in myopia prevention.Policymakers should prioritize outdoor activity programs at the primary school level and develop tailored prevention strategies based on local resource availability.This study provides empirical evidence for developing scientifically sound,cost-effective myopia prevention strategies for children and adolescents,with relevant implications for other developing countries facing a high myopia burden.展开更多
The traffic in developing countries presents its own specificity,notably due to the heterogeneous traffic and a weak-lane discipline.This leads to differences in driver behavior between these countries and developed c...The traffic in developing countries presents its own specificity,notably due to the heterogeneous traffic and a weak-lane discipline.This leads to differences in driver behavior between these countries and developed countries.Knowing that the analysis of the drivers from developed countries leads the design of the majority of driver models,it is not surprising that the simulations performed using these models do not match thefield data of the developing countries.This article presents a systematic review of the literature on modeling driving behaviors in the context of developing countries.The study focuses on the microsimulation approaches,and specifically on the multiagent paradigm,that are considered suitable for reproducing driving behaviors with accuracy.The major contributions from the recent literature are analyzed.Three major scientific challenges and related minor research directions are described.展开更多
The corona virus disease 2019(COVID-19)pandemic has increased awareness towards maintaining physical distancing during transportation-related activities.This study pre-sents a microsimulation model to explore operatio...The corona virus disease 2019(COVID-19)pandemic has increased awareness towards maintaining physical distancing during transportation-related activities.This study pre-sents a microsimulation model to explore operational measures to maintain physical dis-tance among railway station passengers.The secondary and primary data obtained from field surveys are utilized to construct and calibrate the model.The peak hour data is employed to investigate the worst-case conditions.The calibrated model is then utilized to evaluate several operational measures,i.e.,changing the headway,increasing the train capacity,increasing the train door duration,and changing the train door rules.From the simulation,it is found that changing the train door rules was ineffective if it was individ-ually implemented.It is concluded that a combination of operational measures provides additional benefits for maintaining physical distancing among passengers.展开更多
High-granularity vehicle trajectory data can help researchers develop traffic simulation models,understand traffic flow characteristics,and thus propose insightful strategies for road traffic management.This paper pro...High-granularity vehicle trajectory data can help researchers develop traffic simulation models,understand traffic flow characteristics,and thus propose insightful strategies for road traffic management.This paper proposes a novel vehicle trajectory extraction method that can extract high-granularity vehicle trajectories from aerial videos.The proposed method includes video calibration,vehicle detection and tracking,lane marking identification,and vehicle motion characteristics calculation.In particular,the authors propose a Monte-Carlo-based lane marking identification approach to identify each vehicle's lane.This is a challenging problem for vehicle trajectory extraction,especially when the aerial videos are taken from a high altitude.The authors applied the proposed method to extract vehicle trajectories from several high-resolution aerial videos recorded from helicopters.The extracted dataset is named by the High-Granularity Highway Simulation(HIGH-SIM)vehicle trajectory dataset.To demonstrate the effectiveness of the proposed method and understand the quality of the HIGHSIM dataset,we compared the HIGH-SIM dataset with a well-known dataset,the NGSIM US-101 dataset,regarding the accuracy and consistency aspects.The comparison results showed that the HIGH-SIM dataset has more reasonable speed and acceleration distributions than the NGSIM US-101 dataset.Also,the internal and platoon consistencies of the HIGH-SIM dataset give lower errors compared to the NGSIM US-101 dataset.To benefit future research,the authors have published the HIGH-SIM dataset online for public use.展开更多
Purpose–This research paper aims to investigate the effects of gradual deployment of market penetration rates(MPR)of connected vehicles(MPR of CVs)on delay time and fuel consumption.Design/methodology/approach–A rea...Purpose–This research paper aims to investigate the effects of gradual deployment of market penetration rates(MPR)of connected vehicles(MPR of CVs)on delay time and fuel consumption.Design/methodology/approach–A real-world origin-destination demand matrix survey was conducted in Boston,MA to identify the number of peak hour passing vehicles in the case study.Findings–The results showed that as the number of CVs(MPR)in the network increases,the total delay time decreases by an average of 14%and the fuel consumption decreases by an average of 56%,respectively,from scenarios 3 to 15 compared to scenario 2.Research limitations/implications–The first limitation of this study was considering a small network.The considered network shows a small part of the case study.Originality/value–This study can be a milestone for future research regarding gradual deployment of CVs’effects on transport networks.Efficient policy(s)may define based on the results of this network for Brockton transport network.展开更多
As congestion grows in metropolitan areas, agencies tend to utilize managed lanes on their freeway systems. Managed lanes have several forms and names, such as high-occupancy vehicle （HOI0 lanes, high-occupancy toll ...As congestion grows in metropolitan areas, agencies tend to utilize managed lanes on their freeway systems. Managed lanes have several forms and names, such as high-occupancy vehicle （HOI0 lanes, high-occupancy toll （HOT） lanes, express lanes, and bus-only lanes. Although managed lanes have received significant attention as they increased the overall throughput and improved mobility without adding more lanes, little has been known about their operational capabilities. In addition, calibrating managed lane facilities can be chal- lenging as they do not necessarily follow the same behavior with general purpose freeway lanes. This paper presents an operational analysis of two HOT lane segments located in South Florida. The sites are one-lane and two-lane segments separated by flexible pylons （FPs）. The paper includes a macroscopic capacity analysis, and a microscopic calibration of the two sites using VISSIM microsimulation. The research findings assist in determining the capacity and speed-flow relationship of these segments, and also provide guidance for microsimulation model calibration for practitioners. The results of the study indicate that the percent drop in capacity for the one-lane FP site is 7.6% while the flow did not substantially change after the breakdown in the two-lane FP site. The research findings also include guidelines for simulating the breakdown events and calibrating one-lane and two-lane managed lane facilities in VISSIM microsimulation software. The Wiedemann car-following parameters （CC0 = 3.9 ft, CC1 = 1.9 s, CC2 - 26.25 ft, CC4 = -0.35, and CC5 = 0.35） provided the best fit for the one-lane FP site, while the combination （CCO = 4.92 ft, CC1= 1.9 s, CC2 = 39.37 ft, CC4 = -0.7, and CC5 = 0.7） parameters is recommended for the two-lane FP site.展开更多
Purpose–This paper aims to present a summary of the performance measurement and evaluation plan of the Wyoming connected vehicle(CV)Pilot Deployment Program(WYDOT Pilot).Design/methodology/approach–This paper identi...Purpose–This paper aims to present a summary of the performance measurement and evaluation plan of the Wyoming connected vehicle(CV)Pilot Deployment Program(WYDOT Pilot).Design/methodology/approach–This paper identified 21 specific performance measures as well as approaches to measure the benefits of the WYDOT Pilot.An overview of the expected challenges that might introduce confounding factors to the evaluation effort was outlined in the performance management plan to guide the collection of system performance data.Findings–This paper presented the data collection approaches and analytical methods that have been established for the real-life deployment of the WYDOT CV applications.Five methodologies for assessing 21 specific performance measures contained within eight performance categories for the operational and safety-related aspects.Analyses were conducted on data collected during the baseline period,and pre-deployment conditions were established for 1 performance measures.Additionally,microsimulation modeling was recommended to aid in evaluating the mobility and safety benefits of the WYDOT CV system,particularly when evaluating system performance under various CV penetration rates and/or CV strategies.Practical implications–The proposed performance evaluation framework can guide other researchers and practitioners identifying the best performance measures and evaluation methodologies when conducting similar research activities.Originality/value–To the best of the authors’knowledge,this is thefirst research that develops performance measures and evaluation plan for low-volume rural freeway CV system under adverse weather conditions.This paper raised some early insights into how CV technology might achieve the goal of improving safety and mobility and has the potential to guide similar research activities conducted by other agencies.展开更多
Non-commercial Land Ports of Entry(LPOEs)are unique transportation facilities controlling the ingress and egress of passenger vehicles from Mexico to the United States and vice versa.The calibration of microscopic tra...Non-commercial Land Ports of Entry(LPOEs)are unique transportation facilities controlling the ingress and egress of passenger vehicles from Mexico to the United States and vice versa.The calibration of microscopic traffic simulation models of non-commercial LPOEs requires a deep understanding of operational processes and driving behavior at these facilities.This paper provides a methodology to guide modelers in calibrating microscopic traffic simulation models of non-commercial LPOEs.The methodology establishes a common framework for modeling operational processes and traffic operations.Moreover,the methodology includes the value of four state variables that characterizes operations of passenger vehicles at non-commercial LPOEs.These variables are speed,acceleration,deceleration,and headway.The authors evaluated this methodology using the Otay Mesa non-commercial LPOE as a case study.Results showed that this methodology could be potentially used to model non-commercial LPOEs along the US-Mexico border and other border regions worldwide.展开更多
An error in a previous publication in the calculation of the average age at first infection for the model is corrected here.The average age at first infection for the effective contact rates used to generate the data ...An error in a previous publication in the calculation of the average age at first infection for the model is corrected here.The average age at first infection for the effective contact rates used to generate the data ranges from 1.2 to 3.3 years of age instead of 3e5 years of age as advertised in the previous version of the paper.This change has an effect on the force of infection generated by this model.In this corrigendum,we demonstrate the correct method to calculate the average age at first infection for the model.We compare the forces of infection that correspond to these ages in our model with the forces of infection in other endemic populations.We show that the modified age range corresponds to forces of infection which are higher than those that are known to exist in historical studies of polioendemic regions.Thus,the results in the paper have limited applicability to real-world endemic situations.展开更多
Background:Small populations that have been isolated by conflict make vaccination and surveillance difficult,threatening polio eradication.Silent circulation is caused by asymptomatic infections.It is currently not cl...Background:Small populations that have been isolated by conflict make vaccination and surveillance difficult,threatening polio eradication.Silent circulation is caused by asymptomatic infections.It is currently not clear whether the dynamics of waning immunity also influence the risk of silent circulation in the absence of vaccination.Such circulation can,nevertheless,be present following a declaration of elimination as a result of inadequate acute flaccid paralysis surveillance(AFPS)or environmental surveillance(ES).Methods:We have constructed a stochastic model to understand how stochastic effects alter the ability of small populations to sustain virus circulation in the absence of vaccination.We analyzed how the stochastic process determinants of the duration of silent circulation that could have been detected by ES were affected by R0,waning dynamics,population size,and AFPS sensitivity in a discrete individual stochastic model with homogeneous contagiousness and random mixing.We measured the duration of silent circulation both by the interval between detected acute flaccid paralysis(AFP)cases and the duration of circulation until elimination.Results:As R0 increased and population size increased,the interval between detected AFP cases and the duration of circulation until elimination increased.As AFPS detection rates decreased,the interval between detected AFP cases increased.There was up to a 22%chance of silent circulation lasting for more than 3 years with 100%AFP detection.The duration of silent circulation was not affected by the waning immunity dynamics.Conclusion:We demonstrated that small populations have the potential to sustain prolonged silent circulation.Surveillance in these areas should be intensified before declaring elimination.To further validate these conclusions,it is necessary to realistically relax the simplifying assumptions about mixing and waning.展开更多
An offset T-intersection splits a conventional four leg intersection into two three-leg T-intersections to reduce the number of conflicts. While the safety benefits of offset T-intersections have been widely documente...An offset T-intersection splits a conventional four leg intersection into two three-leg T-intersections to reduce the number of conflicts. While the safety benefits of offset T-intersections have been widely documented, the effects on operations are not well understood. To fix that, this paper employed microsimulation modeling to investigate the differences in operational performance between offset T-intersections and four-leg standard intersections under various traffic demands, intersection spacings, and signal timing schemes for three development types: superstore, hybrid gas station, and residential area. Queue length and delay were employed as measurements of effectiveness. Based on microsimulation modeling, we found that under most of the tested scenarios, offset T-intersections were superior to four-leg intersections in terms of reducing delay for the main street traffic. In addition, we found that the left–right (L-R) offset T-intersection configuration outperformed the right-left (R-L) offset configuration in terms of preventing main-street left turn queue spillback. Based on the simulation results, the paper provided practice-ready guidelines on selecting an optimum intersection configuration for each specific development type given the volume demands and known geometric constraints for a given site.展开更多
文摘Purpose:The coronavirus disease-2019(COVID-19)pandemic in the United States led to nationwide stay-at-home orders and school closures.Declines in energy expenditure resulting from canceled physical education classes and reduced physical activity may elevate childhood obesity risk.This study estimated the impact of COVID-19 on childhood obesity.Methods:A microsimulation model simulated the trajectory of a nationally representative kindergarten cohort’s body mass index z-scores and childhood obesity prevalence from April 2020 to March 2021 under the control scenario without COVID-19 and under the 4 alternative scenarios with COVID-19—Scenario 1:2-month nationwide school closure in April and May 2020;Scenario 2:Scenario 1 followed by a 10%reduction in daily physical activity in the summer from June to August;Scenario 3:Scenario 2 followed by 2-month school closure in September and October;and Scenario 4:Scenario 3 followed by an additional 2-month school closure in November and December.Results:Relative to the control scenario without COVID-19,Scenarios 1,2,3,and 4 were associated with an increase in the mean body mass index z-scores by 0.056(95%confidence interval(95%CI):0.0550.056),0.084(95%CI:0.0840.085),0.141(95%CI:0.1400.142),and 0.198(95%CI:0.1970.199),respectively,and an increase in childhood obesity prevalence by 0.640(95%CI:0.5150.765),0.972(95%CI:0.8191.126),1.676(95%CI:1.4751.877),and 2.373(95%CI:2.1352.612)percentage points,respectively.Compared to girls and non-Hispanic whites and Asians,the impact of COVID-19 on childhood obesity was modestly larger among boys and non-Hispanic blacks and Hispanics,respectively.Conclusion:Public health interventions are urgently called to promote an active lifestyle and engagement in physical activity among children to mitigate the adverse impact of COVID-19 on unhealthy weight gains and childhood obesity.
文摘AIM: To hypothesize that the product of calculated Model for End-Stage Liver Disease score excluding exception points and donor age(D-MELD) risk capping ± Rule 14 could improve post liver transplant and overall survival after listing.METHODS: Probabilities derived from the United Network for Organ Sharing database between 2002 and 2004 were used to simulate potential outcomes for all patients listed for transplantation. The Markov simula-tion was then modified by screening matches using a 1200 or 1600 D-MELD risk cap ± allowing transplants for Model for End-Stage Liver Disease(MELD) ≤ 14(Rule 14). The differential impact of the rule changes was assessed.RESULTS: The Markov simulation accurately reproduced overall and post transplant survival. A 1200 D-MELD risk cap improved post-transplant survival. Both the 1200 and 1600 risk caps improved overall survival for waitlisted patients. The addition of Rule 14 further improved post transplant and overall survival by redistribution of donor livers to recipients in higher MELD subgroups. The mechanism for improved overall and post-transplant survival after listing was due to shifting a larger percentage of transplants to the moderate MELD score subgroup(MELD 15-29) while also ensuring that high MELD recipients have livers of high quality to achieve excellent post transplant survival.CONCLUSION: A 1200 D-MELD risk cap + Rule 14 provided the greatest overall benefit primarily by focusing liver transplantation towards the moderate MELD recipient.
基金The research reported in this paper was part of the UK Infrastructure Transitions Research Consortium(ITRC)funded by the Engineering and Physical Sciences Research Council under program grant EP/I01344X/1.
文摘High quality infrastructure is crucial to economic success and the sustainability of society.Infrastructures for services,such as transport,energy,and water supply,also have long lead times,and therefore require effective long-term planning.In this paper,we report on work undertaken as part of the UK Infrastructure Transitions Research Consortium to construct long-term models of demographic change which can help to inform infrastructure planning for transport,energy,and water as well as IT and waste.A set of demographic microsimulation models(MSM),which are spatially disaggregate to the geography of UK Local Authorities,provides a high level of detail for understanding the drivers of changing patterns of demand.However,although robust forecasting models are required to support projections based on the notion of‘predict-and-provide,’the potential for behavioral adaptation is also an important consideration in this context.In this paper,we therefore establish a framework for linkage of a MSM of household composition,with behavior relating to the consumption of energy.We will investigate variations in household energy consumption within and between different household groups.An appropriate range of household types will be defined through the application of decision trees to consumption data from a detailed survey produced by the UK Department of Energy and Climate Change.From this,analysis conclusions will be drawn about the impact of changing demographics at both household and individual level,and about the potential effect of behavioral adjustments for different household groups.
文摘This research assessed the impact of efficiently expanding the biking network in Atlanta,Georgia,using dedicated lanes for bicycles.A total of three different conditions,i.e.,exist-ing,proposed(by the authors),and alternative(suggested by the City of Atlanta)condi-tions,were modeled to see the effectiveness of bike infrastructure design improvement and expansion.Trajectory data collected from the VISSIM simulation model were used in the Federal Highway Administration(FHWA)’s surrogate safety assessment model(SSAM)to analyze the safety effect on the bike infrastructure improvement and expansion.Based on the results,both the proposed and alternative conditions resulted in safer travel through the network during the peak hour period without any apparent deterioration in delays.For instance,compared to the existing condition,the average stop delays decreased from 190 s to 164 s for the proposed and the alternative conditions.These findings showed that the introduction of bicycle lanes and narrower lanes for automobiles may not adversely affect the peak hour congestion.Also,fewer conflicts were observed in the sim-ulated network of proposed and alternative conditions compared to existing conditions.Conflicts involving bicyclists were also reduced since the bicyclists can use their own lanes and do not have to interact with automobile traffic in the sharrows.
基金supported by United States Department of Transportation grant DTRT13-G-UTC42
文摘Traffic safety and performance measures such as crash risk and queue lengths or travel times are influenced by several important factors including those related to environment,human,and roadway design,especially at intersections.Previous research has studied different aspects related to these factors,yet these characteristics are not fully investigated with a focus on age and experience of drivers.In this paper,we investigate this issue by using a two-phase approach via a case study application on a critical T-intersection in the City of Tallahassee,Florida.The first phase includes a scenario-based microsimulation analysis through the use of a microscopic simulation software,namely VISSIM,to illustrate the variations in traffic performance measures with respect to driver compositions of different age groups in the traffic stream.A variety of scenarios is created where the driving characteristics are provided as inputs to these scenarios in terms of decision making and risk taking.This is also supported by a sensitivity analysis conducted based on the driver composition in the traffic.The second phase includes the analysis of microsimulation outputs via a tool developed by Federal Highway Administration tool,namely the Surrogate Safety Assessment Model(SSAM),in order to determine the traffic conflicts that occur in each scenario.These conflicts are also compared with real-life crash data for validation purposes.Results show that(a) the differences in risk perception that affect driving behavior might be significant in influencing traffic safety and performance measures,and(b) the proposed approach is considerably successful in simulating the actual crash conflict points.
基金Ghana Highway Authority(GHA)for their support towards this work。
文摘Roundabouts are very useful when flows are balanced but can have operational challenges when flows increase.Most roundabouts on arterial roadways in Ghana experience recurring congestion during peak traffic.The four roundabouts between Ejisu Municipality and Asokwa Municipality on the N6 highway are typical of the situation found on arterials countrywide.They experience recurring long queues and delays during the peak hours and over-representation of truck rollover accidents.In Ghana,historically,most roundabouts with capacity problems have been developed into interchanges at very high cost without consideration of other effective at-grade configurations.When roundabouts are signalized,various configurations can be explored to enhance capacity while preserving the safety benefits.Using simulation techniques,various configurations and design options were tested for their effectiveness at two of the roundabouts,located at KNUST police station and Ejisu,with similar demand and high left turning volumes.The objectives of this study were to a)evaluate the performance of the selected roundabouts on the corridor;b)explore alternative intersection configurations to improve capacity and delay.Using video data collection techniques,2-h time stamped footages of AM and PM peak traffic flows were captured for two days.Geometric design parameters of the existing roundabouts,queue lengths,travel times,and approach flows were also captured.VISSIM models of the selected roundabouts were developed and calibrated for the baseline conditions.Signalized unconventional roundabout configuration,with a phase for major road through traffic were simulated and assessed for capacity,delay and queue length.The results showed that signalized roundabout intersections effectively increased capacity by as much as 50%in some cases,reduced delay and queue length significantly,and maintained the benefits of roundabouts including safety.The performance could be further enhanced by introducing separate left turn phases to reduce conflicts or through a right turn U-turn(RTUT)concept.
基金supports from the National Natural Science Foundation of China(No.71761147004)the Agricultural Science and Technology Innovation Program(No.2021-RY-01)+1 种基金Zhejiang University-IFPRI Center for International Development Studiesthe Consultative Group on International Agricultural Research(CGIAR)Program on Policies,Institutions,and Markets(PIM)led by IFPRI.
文摘Chinese migrant workers are very exposed to the shocks caused by the COVID-19 pandemic.Falling remittances adversely affect their families who rely on remittance incomes.The impacts of COVID-19 on migrants and remittance-receiving households are assessed using a nationally representative household dataset and a microsimulation model.We found about 70 percent of migrant workers lost part of their wage income during the pandemic lockdown period and rural migrants working in small and medium enterprises were affected the most.This led to about 50 percent of remittance-receiving households being affected adversely by falling remittances,and the average decline in such income was more than 45 percent.Nearly 13 percent of pre-pandemic nonpoor remittance-receiving households could fall into poverty,raising the poverty rate among remittancereceiving households by 4 percentage points.Many households that were poor prior to the pandemic became more impoverished.The results indicate that social protection programs targeting vulnerable migrants and their families at home are important.
基金support from China Schol-arship Council(CSC file No.201708340072).
文摘Background:The effectiveness of lung cancer screening with low-dose computed tomography(LDCT)has been established.The current study evaluates the cost-effectiveness of lung cancer screening with LDCT in a general population in China.Methods:A previously validated micro-simulation model was used to simulate a cohort of men and women on a lifetime horizon in the presence and absence of LDCT screening.The modeling data were collected from numerous national and international sources.Simulated screening scenarios included different combinations of screening intervals and start and stop ages.Additional costs(valued in Chinese Yuan,CNY;1 USD=6.8976 CNY,1 EUR=7.8755 CNY in 2020),life-years gained(LYG)and mortality reduction due to screening were also determined.The costs and life-years were discounted by 3%.All results were scaled to 1,000 individuals.The average cost-effectiveness ratio(ACER)was calculated.A willingness-to-pay threshold of CNY 217.3k/LYG was considered.A healthcare system perspective was adopted.Results:Compared to no screening,lung cancer screening by LDCT in a general Chinese population yielded 21.0-36.7 LYG in men and 9.2-16.6 LYG in women across the scenarios.For men,biennial LDCT screening yielded an ACER of CNY 171.4k-306.3k/LYG relative to no screening.Biennial screening performed between 55 and 75 years of age was optimal at the defined threshold;it resulted in CNY 174.6k/LYG and a lung cancer mortality reduction of 9.1%,and this scenario had a 75%probability of being cost-effective.For women,the ACER ranged from CNY 364.2k to 1193.3k/LYG.Conclusions:In China,lung cancer screening with LDCT in the general population including never smokers could be cost-effective for men with 75%probability,but not for women.The optimal strategy for men would be performing biennial screening between 55 and 75 years of age.
基金supported by the National Natural Science Foundation of China(72293585,72404183).
文摘Introduction:Myopia has emerged as a major public health challenge affecting the visual health of children and adolescents in China.While evidence confirms the effectiveness of outdoor activity in preventing myopia,comprehensive economic analyses of its role in mitigating myopia-related diseases remain limited.Methods:This study employed a microsimulation model to evaluate the cost-effectiveness of increasing outdoor activity across different educational stages—primary,middle,and high school—for myopia prevention in China.The model simulated myopia progression among individuals aged 6 to 18 years,with the intervention defined as an additional 40 minutes of daily outdoor activity.Outcomes measured included changes in myopia prevalence,quality-adjusted life years(QALYs),and associated medical costs.Results:All intervention scenarios proved costeffective,except for those targeting only the high school stage.Interventions focused on primary schools and combined primary–middle school stages not only improved health outcomes but also reduced medical costs.While the all-stages intervention yielded the greatest health benefits,its higher implementation costs make it more suitable for regions with greater resources.Conclusion:These findings highlight the critical importance of early intervention in myopia prevention.Policymakers should prioritize outdoor activity programs at the primary school level and develop tailored prevention strategies based on local resource availability.This study provides empirical evidence for developing scientifically sound,cost-effective myopia prevention strategies for children and adolescents,with relevant implications for other developing countries facing a high myopia burden.
基金supported by the ERAMUS+Higher Education Learning under Grant No.1953215 of Hasselt University Belgium.Alexandre Lombard is supported by the National Inter-UT Project SMART-E2AU 2018-2022 of the“Universitéde Technologie de Belfort-Montbéliard”,France.Stéphane GallandThomas Martinet are supported by the EU project H2020 REDREAM,under Grant No.957837.
文摘The traffic in developing countries presents its own specificity,notably due to the heterogeneous traffic and a weak-lane discipline.This leads to differences in driver behavior between these countries and developed countries.Knowing that the analysis of the drivers from developed countries leads the design of the majority of driver models,it is not surprising that the simulations performed using these models do not match thefield data of the developing countries.This article presents a systematic review of the literature on modeling driving behaviors in the context of developing countries.The study focuses on the microsimulation approaches,and specifically on the multiagent paradigm,that are considered suitable for reproducing driving behaviors with accuracy.The major contributions from the recent literature are analyzed.Three major scientific challenges and related minor research directions are described.
文摘The corona virus disease 2019(COVID-19)pandemic has increased awareness towards maintaining physical distancing during transportation-related activities.This study pre-sents a microsimulation model to explore operational measures to maintain physical dis-tance among railway station passengers.The secondary and primary data obtained from field surveys are utilized to construct and calibrate the model.The peak hour data is employed to investigate the worst-case conditions.The calibrated model is then utilized to evaluate several operational measures,i.e.,changing the headway,increasing the train capacity,increasing the train door duration,and changing the train door rules.From the simulation,it is found that changing the train door rules was ineffective if it was individ-ually implemented.It is concluded that a combination of operational measures provides additional benefits for maintaining physical distancing among passengers.
基金supported in part by the United States National Science Foundation Grant#1932452 and Federal Highway Administration Grant#DTFH6116D00030.
文摘High-granularity vehicle trajectory data can help researchers develop traffic simulation models,understand traffic flow characteristics,and thus propose insightful strategies for road traffic management.This paper proposes a novel vehicle trajectory extraction method that can extract high-granularity vehicle trajectories from aerial videos.The proposed method includes video calibration,vehicle detection and tracking,lane marking identification,and vehicle motion characteristics calculation.In particular,the authors propose a Monte-Carlo-based lane marking identification approach to identify each vehicle's lane.This is a challenging problem for vehicle trajectory extraction,especially when the aerial videos are taken from a high altitude.The authors applied the proposed method to extract vehicle trajectories from several high-resolution aerial videos recorded from helicopters.The extracted dataset is named by the High-Granularity Highway Simulation(HIGH-SIM)vehicle trajectory dataset.To demonstrate the effectiveness of the proposed method and understand the quality of the HIGHSIM dataset,we compared the HIGH-SIM dataset with a well-known dataset,the NGSIM US-101 dataset,regarding the accuracy and consistency aspects.The comparison results showed that the HIGH-SIM dataset has more reasonable speed and acceleration distributions than the NGSIM US-101 dataset.Also,the internal and platoon consistencies of the HIGH-SIM dataset give lower errors compared to the NGSIM US-101 dataset.To benefit future research,the authors have published the HIGH-SIM dataset online for public use.
文摘Purpose–This research paper aims to investigate the effects of gradual deployment of market penetration rates(MPR)of connected vehicles(MPR of CVs)on delay time and fuel consumption.Design/methodology/approach–A real-world origin-destination demand matrix survey was conducted in Boston,MA to identify the number of peak hour passing vehicles in the case study.Findings–The results showed that as the number of CVs(MPR)in the network increases,the total delay time decreases by an average of 14%and the fuel consumption decreases by an average of 56%,respectively,from scenarios 3 to 15 compared to scenario 2.Research limitations/implications–The first limitation of this study was considering a small network.The considered network shows a small part of the case study.Originality/value–This study can be a milestone for future research regarding gradual deployment of CVs’effects on transport networks.Efficient policy(s)may define based on the results of this network for Brockton transport network.
基金the support and encouragement of PTV Group Management during this research study
文摘As congestion grows in metropolitan areas, agencies tend to utilize managed lanes on their freeway systems. Managed lanes have several forms and names, such as high-occupancy vehicle （HOI0 lanes, high-occupancy toll （HOT） lanes, express lanes, and bus-only lanes. Although managed lanes have received significant attention as they increased the overall throughput and improved mobility without adding more lanes, little has been known about their operational capabilities. In addition, calibrating managed lane facilities can be chal- lenging as they do not necessarily follow the same behavior with general purpose freeway lanes. This paper presents an operational analysis of two HOT lane segments located in South Florida. The sites are one-lane and two-lane segments separated by flexible pylons （FPs）. The paper includes a macroscopic capacity analysis, and a microscopic calibration of the two sites using VISSIM microsimulation. The research findings assist in determining the capacity and speed-flow relationship of these segments, and also provide guidance for microsimulation model calibration for practitioners. The results of the study indicate that the percent drop in capacity for the one-lane FP site is 7.6% while the flow did not substantially change after the breakdown in the two-lane FP site. The research findings also include guidelines for simulating the breakdown events and calibrating one-lane and two-lane managed lane facilities in VISSIM microsimulation software. The Wiedemann car-following parameters （CC0 = 3.9 ft, CC1 = 1.9 s, CC2 - 26.25 ft, CC4 = -0.35, and CC5 = 0.35） provided the best fit for the one-lane FP site, while the combination （CCO = 4.92 ft, CC1= 1.9 s, CC2 = 39.37 ft, CC4 = -0.7, and CC5 = 0.7） parameters is recommended for the two-lane FP site.
文摘Purpose–This paper aims to present a summary of the performance measurement and evaluation plan of the Wyoming connected vehicle(CV)Pilot Deployment Program(WYDOT Pilot).Design/methodology/approach–This paper identified 21 specific performance measures as well as approaches to measure the benefits of the WYDOT Pilot.An overview of the expected challenges that might introduce confounding factors to the evaluation effort was outlined in the performance management plan to guide the collection of system performance data.Findings–This paper presented the data collection approaches and analytical methods that have been established for the real-life deployment of the WYDOT CV applications.Five methodologies for assessing 21 specific performance measures contained within eight performance categories for the operational and safety-related aspects.Analyses were conducted on data collected during the baseline period,and pre-deployment conditions were established for 1 performance measures.Additionally,microsimulation modeling was recommended to aid in evaluating the mobility and safety benefits of the WYDOT CV system,particularly when evaluating system performance under various CV penetration rates and/or CV strategies.Practical implications–The proposed performance evaluation framework can guide other researchers and practitioners identifying the best performance measures and evaluation methodologies when conducting similar research activities.Originality/value–To the best of the authors’knowledge,this is thefirst research that develops performance measures and evaluation plan for low-volume rural freeway CV system under adverse weather conditions.This paper raised some early insights into how CV technology might achieve the goal of improving safety and mobility and has the potential to guide similar research activities conducted by other agencies.
文摘Non-commercial Land Ports of Entry(LPOEs)are unique transportation facilities controlling the ingress and egress of passenger vehicles from Mexico to the United States and vice versa.The calibration of microscopic traffic simulation models of non-commercial LPOEs requires a deep understanding of operational processes and driving behavior at these facilities.This paper provides a methodology to guide modelers in calibrating microscopic traffic simulation models of non-commercial LPOEs.The methodology establishes a common framework for modeling operational processes and traffic operations.Moreover,the methodology includes the value of four state variables that characterizes operations of passenger vehicles at non-commercial LPOEs.These variables are speed,acceleration,deceleration,and headway.The authors evaluated this methodology using the Otay Mesa non-commercial LPOE as a case study.Results showed that this methodology could be potentially used to model non-commercial LPOEs along the US-Mexico border and other border regions worldwide.
文摘An error in a previous publication in the calculation of the average age at first infection for the model is corrected here.The average age at first infection for the effective contact rates used to generate the data ranges from 1.2 to 3.3 years of age instead of 3e5 years of age as advertised in the previous version of the paper.This change has an effect on the force of infection generated by this model.In this corrigendum,we demonstrate the correct method to calculate the average age at first infection for the model.We compare the forces of infection that correspond to these ages in our model with the forces of infection in other endemic populations.We show that the modified age range corresponds to forces of infection which are higher than those that are known to exist in historical studies of polioendemic regions.Thus,the results in the paper have limited applicability to real-world endemic situations.
基金This research was supported in part by the Army Research Office under MURI grant 558153-MA-MUR,Prime Award W91 INF-11-1-0036.
文摘Background:Small populations that have been isolated by conflict make vaccination and surveillance difficult,threatening polio eradication.Silent circulation is caused by asymptomatic infections.It is currently not clear whether the dynamics of waning immunity also influence the risk of silent circulation in the absence of vaccination.Such circulation can,nevertheless,be present following a declaration of elimination as a result of inadequate acute flaccid paralysis surveillance(AFPS)or environmental surveillance(ES).Methods:We have constructed a stochastic model to understand how stochastic effects alter the ability of small populations to sustain virus circulation in the absence of vaccination.We analyzed how the stochastic process determinants of the duration of silent circulation that could have been detected by ES were affected by R0,waning dynamics,population size,and AFPS sensitivity in a discrete individual stochastic model with homogeneous contagiousness and random mixing.We measured the duration of silent circulation both by the interval between detected acute flaccid paralysis(AFP)cases and the duration of circulation until elimination.Results:As R0 increased and population size increased,the interval between detected AFP cases and the duration of circulation until elimination increased.As AFPS detection rates decreased,the interval between detected AFP cases increased.There was up to a 22%chance of silent circulation lasting for more than 3 years with 100%AFP detection.The duration of silent circulation was not affected by the waning immunity dynamics.Conclusion:We demonstrated that small populations have the potential to sustain prolonged silent circulation.Surveillance in these areas should be intensified before declaring elimination.To further validate these conclusions,it is necessary to realistically relax the simplifying assumptions about mixing and waning.
文摘An offset T-intersection splits a conventional four leg intersection into two three-leg T-intersections to reduce the number of conflicts. While the safety benefits of offset T-intersections have been widely documented, the effects on operations are not well understood. To fix that, this paper employed microsimulation modeling to investigate the differences in operational performance between offset T-intersections and four-leg standard intersections under various traffic demands, intersection spacings, and signal timing schemes for three development types: superstore, hybrid gas station, and residential area. Queue length and delay were employed as measurements of effectiveness. Based on microsimulation modeling, we found that under most of the tested scenarios, offset T-intersections were superior to four-leg intersections in terms of reducing delay for the main street traffic. In addition, we found that the left–right (L-R) offset T-intersection configuration outperformed the right-left (R-L) offset configuration in terms of preventing main-street left turn queue spillback. Based on the simulation results, the paper provided practice-ready guidelines on selecting an optimum intersection configuration for each specific development type given the volume demands and known geometric constraints for a given site.
