A model is proposed to describe the passengers’route choice behaviors in urban railway traffic with stochastic link capacity degradation by considering two types of demand,sensitive and insensitive passenger.The inse...A model is proposed to describe the passengers’route choice behaviors in urban railway traffic with stochastic link capacity degradation by considering two types of demand,sensitive and insensitive passenger.The insensitive passengers choose their route without paying much attention to congestion.To the contrary,sensitive passengers who consider route congestion choose travel route based on generalized cost.An equilibrium state is given by variational inequalities in terms of travel generalized cost,which is represented by the combinations of mean and variance of total travel time.The diagonalization algorithm is given to solve this programming.Results show that insensitive passengers have large effects on the path choice than sensitive ones,especially for the larger demand.展开更多
Dhaka, the capital city of Bangladesh is one of the most overpopulated city in the world and traffic jam is the most severe and regular affliction in the daily life. Also, the existing vehicles are not sufficient in c...Dhaka, the capital city of Bangladesh is one of the most overpopulated city in the world and traffic jam is the most severe and regular affliction in the daily life. Also, the existing vehicles are not sufficient in compared to the population of the city. People have to spend many hours simply sitting in the traffic jam. This lessens the productivity of people and brings sufferings to them. Gulshan-Banani-HatirJheel area is the busiest regions within the city and face severe traffic jam during working hours. These lakes are totally unused. Therefore, there is a possibility to build a waterways network for passengers transport through these lakes. This will reduce the affliction of people via reducing traffic jam. The proposed transportation networks will also preserve the natural environment of the lakes and bring a source of entertainment in the city life. Many developed cities in the world like London, New York, Paris, Venice, Shanghai etc. already have implemented waterways network inside the city and successfully made the best use of cistern side.展开更多
Ten years of financial stability in Brazilian economy have gone. In this period, the regional transportation of passengers suffered exogenous impacts: economical crises, airport crises and great proportions' acciden...Ten years of financial stability in Brazilian economy have gone. In this period, the regional transportation of passengers suffered exogenous impacts: economical crises, airport crises and great proportions' accidents, as well as impacts which were intern to the system: institutional changes (liberation of tariff promotions, many companies establishing themselves and also coming to bankruptcy), creation of regulating institutions in the air transportation as well as the land transportation. Theoretically, it is expected that these changes have generated impacts in the demand for trips, since an environment regulated with more flexible prices and higher amounts of companies would generate a competitive environment in which the companies could struggle to attract their demand. On the other hand, the impacts which are exogenous to the system can generate responses in the sense of restoring the balance of demand. Thus, based on the theoretical experience, this article aims at analyzing empirically, through categorical variables, if there were impacts on the demand for regional trips in Brazil due to the internal or external changes. In order to perform this, monthly data from January, 1999 to December, 2009 are utilized and estimates are calculated making use of SUR (seemingly unrelated regressions). As a result, we have the meaning of the internal and external impacts related to air and land transports, identifying that the worldwide economic crisis generated an impact at the level of the demand for transportation and also that the flexibility of tariffs allowed by ANTT (Ag^ncia Nacional de Transportes Terrestres) had an equal impact on the demand for land transportation.展开更多
A taxi company in Shanghai has announced its plan to equip half of its fleet - about 6,000 taxis - with digital video recorders by the end of the year. According to the company, there will be four cameras per taxi, in...A taxi company in Shanghai has announced its plan to equip half of its fleet - about 6,000 taxis - with digital video recorders by the end of the year. According to the company, there will be four cameras per taxi, installed internally as well as externally to ensure the safety of both passengers and drivers.展开更多
Evacuated Tube Transport Technologies (ET3) offers the potential for more than an order of magnitude improvement in transportation efficiency, speed, cost, and effectiveness. An ET3 network may be optimized to susta...Evacuated Tube Transport Technologies (ET3) offers the potential for more than an order of magnitude improvement in transportation efficiency, speed, cost, and effectiveness. An ET3 network may be optimized to sustainably displace most global transportation by car, ship, truck, train, and jet aircraft. To do this, ET3 standards should adhere to certain key principals: maximum value through efficiency, reliability, and simplicity; equal consideration for passenger and cargo loads; optimum size; high speed/high frequency operation; demand oriented; random accessibility; scalability; high granularity; automated control; full speed passive switching; open standards of implementation; and maximum use of existing capacities, materials, and processes.展开更多
An estimation approach is proposed in this paper based on the binocular stereovision to collect the degree of crowdedness in public transports. The proposed method combines the disparity with frame differences to extr...An estimation approach is proposed in this paper based on the binocular stereovision to collect the degree of crowdedness in public transports. The proposed method combines the disparity with frame differences to extract the foreground object. An adaptive window normalized cross correlation (NCC) matching and interpolated method is applied to get the sub-pixel image disparity value. Then, the foreground object is projected to the horizontal plane to eliminate the influence of the occlusion and perspective effect. Finally the degree of crowdedness is calculated from the area and the perimeter of the foreground objects. Experimental results show that the proposed method can obtain good estimation results in the simulated scenes in the laboratory and on parking or moving buses. This approach is effective to illumination changes, shadows and occlusion of passengers.展开更多
This paper describes two perspectives to improve the passenger experience.The passenger satisfaction pyramid is introduced,consisting of the base of the pyramid(dissatisfiers)focusing on time well saved and the top of...This paper describes two perspectives to improve the passenger experience.The passenger satisfaction pyramid is introduced,consisting of the base of the pyramid(dissatisfiers)focusing on time well saved and the top of the pyramid(satisfiers)aiming at time well spent.The challenge in planning and design of public transport services is to find the most efficient(set of)design choices.Depending on the context this might either mean focusing on the top or on the bottom of the pyramid.We found that influencing and enhancing the qualities of the satisfiers is far more important than traditional studies showed us.For stations,regression analyses show that dissatisfiers are responsible for explaining almost half of the total score of the station and satisfiers are responsible for the other half of the scores passengers give for the station.We still have to put a lot of energy in getting the basics right,starting in the planning phase,but then we are not allowed to lean back.We have to keep investing in qualities like ambience,comfort and experience which makes the customers truly happy at the end of the day.展开更多
This study analyzes air passenger route choice behavior for long-haul inter-continental travel. It employs the SP (state preference) technique and logit modeling to investigate the impact of route development via ne...This study analyzes air passenger route choice behavior for long-haul inter-continental travel. It employs the SP (state preference) technique and logit modeling to investigate the impact of route development via neighboring countries in the region. With the Japanese government pursuing an increase in international routes at Haneda International Airport, and the Chinese government planning to construct Beijing Capital Second International Airport by 2019, the competition among airports to serve as hubs in Northeast Asia will increase significantly. Korean passengers will have a greater number of route choices when traveling to North America or Europe, utilizing not only direct flights from Incheon International Airport but also flights via Tokyo or Beijing area airports including Haneda International Airport, Narita International Airport, Beijing Capital International Airport and Beijing Capital Second International Airport. Accordingly, passengers will choose among the alternatives by considering fares and flight times. As such, it is essential for airports to offer flights with competitive prices for transit passengers to become successful competitive airports in the region. Therefore, it will become more important for market decision makers to strive toward more attractive ticket prices and better route network quality.展开更多
Periodic frequent pattern discovery is a non-trivial task to discover frequent patterns based on user interests using a periodicity measure.Although conventional algorithms for periodic frequent pattern detection have...Periodic frequent pattern discovery is a non-trivial task to discover frequent patterns based on user interests using a periodicity measure.Although conventional algorithms for periodic frequent pattern detection have numerous applications,there is still little research on periodic frequent pattern detection of individual passengers in the metro.The travel behavior of individual passengers has complex spatio-temporal characteristics in the metro network,which may pose new challenges in discovering periodic frequent patterns of individual metro passengers and developing mining algorithms based on real-world smart card data.This study addresses these issues by proposing a novel pattern for metro passenger travel pattern called periodic frequent passenger traffic patterns with time granularities and station attributes(PFPTS).This discovered pattern can automatically capture the features of the temporal dimension(morning and evening peak hours,week)and the spatial dimension(entering and leaving stations).The corresponding complete mining algorithm with the PFPTS-tree structure has been developed.To evaluate the performance of PFPTS-tree,several experiments are conducted on one-year real-world smart card data collected by an automatic fare collection system in a certain large metro network.The results show that PFPTS-Tree is efficient and can discover numerous interesting periodic frequent patterns of metro passengers in the real-world dataset.展开更多
Periodic pattern mining is of great significance for understanding passenger travel behav-ior,but the previous works mainly focused on the trajectory data and the dimension of the spot/point.Besides,many uncertain fac...Periodic pattern mining is of great significance for understanding passenger travel behav-ior,but the previous works mainly focused on the trajectory data and the dimension of the spot/point.Besides,many uncertain factors(severe weather,traffic accident,etc.)may interfere with discovering original and accurate periodic travel patterns.This paper pro-poses a novel type of travel pattern called motif periodic frequent pattern(MPFP),which captures the periodicity of network temporal motifs of individual metro passengers with higher-order spatio-temporal characteristics considering,uncertain disturbances.We also propose a new complete mining algorithm MPFP-growth to extract MPFP from smart card data(SCD),and apply the real long-time-span experimental data from a large-scale metro system is applied.Results show that frequent-travel metro passengers usually have some typical MPFPs with the temporal periodic characteristic of“week”.Only the top 10 types of all 4624 types account for about 95%of all motifs and the top 5 types constitute about 90%,and the MPFP of the top 3 types of motifs account for nearly 80%of all periodic patterns,in which Mono-MPFP and 2-MPFP are the main ones.The relatively stable time range of MPFP is three months,and the threshold for the optimal uncertain disturbance factor should be set at 5%.Additionally,several interesting typical MPFPs of individual metro commuting passengers and their proportions are introduced to further understand the multifarious variants of MPFP.展开更多
This paper investigates the scale and expression of passengers’anger arising from disputes between drivers and passengers,and between passengers,by surveying a sample of 757 undergraduate students.The bus passengers...This paper investigates the scale and expression of passengers’anger arising from disputes between drivers and passengers,and between passengers,by surveying a sample of 757 undergraduate students.The bus passengers’anger scale and expression inventory(BPASX),a newly-designed questionnaire battery,is used to analyse the anger levels and resulting behaviour expression of passengers in 6-item anger-provoking situations.The analysis shows that a positive correlation exists between the frequency or duration of bus rides and anger levels/external anger expression,while self-adaptive expression is only correlated with frequency.Gender differs only in the violent external expression,where males display a greater preference.Meanwhile,the correlations of anger levels between anger-provoking situations are significantly positive.Moreover,anger expression patterns gradually shift from self-adaptation to external expression as anger levels grow in general,but the variation rules of expression frequency are different.Overall,this study provides a newly effective tool to explore characteristics of the anger expression of bus passengers in different anger-provoking scenarios and demonstrates its variation features when anger levels change.展开更多
This study uses multiple regression to investigate the effects of Land and building use on popuLation, Land price, and passengers. Initialty, we abstract annuat data on Land and buildings usage within a radius of 0 m-...This study uses multiple regression to investigate the effects of Land and building use on popuLation, Land price, and passengers. Initialty, we abstract annuat data on Land and buildings usage within a radius of 0 m-400 m for railway stations and 400 m-800 m for subway stations in Fukuoka, Japan by using the GIS. We then analyze the relationships between 13 factors of rand use and 8 factors of building usage, as well as the related poputation, Land price, and passengers using the quantitative expression method. Using several categories of land use and building usage as explanatory variables, we anatyze the degree to which the selected categories affect population, Land price, and passengers by using the muttiple regression method. This research can aid the further development of land and buitding usage in the future.展开更多
Dear Editor,Lung cancer is a major global health concern,with 2.2 million patients diagnosed in 2020.Non-small cell lung cancer(NSCLC)accounts for 80%of these cases,primarily comprising two subtypes:lung adenocarcinom...Dear Editor,Lung cancer is a major global health concern,with 2.2 million patients diagnosed in 2020.Non-small cell lung cancer(NSCLC)accounts for 80%of these cases,primarily comprising two subtypes:lung adenocarcinoma(LUAD)and squamous cell carcinoma(LUSC)[1].Researchers use immunohisto-chemistry,next-generation sequencing,and single-cell RNA sequencing to study genetic alterations,tumor heterogeneity,and tumor microenvironments,aiming to identify potential therapeutic options for specific NSCLC subtypes[2].展开更多
When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling o...When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling of driving.Ifs fun!展开更多
1 There was a taxi driver who was angry and wanted to finish his shift as soon as possible.When he arrived to pick up his last passenger of the day,he honked the horn(按喇叭),but no one came out of the apartment.Minut...1 There was a taxi driver who was angry and wanted to finish his shift as soon as possible.When he arrived to pick up his last passenger of the day,he honked the horn(按喇叭),but no one came out of the apartment.Minutes later,he honked again,but still there was no reaction.展开更多
基金Project(71525002) supported by China National Funds for Distinguished Young ScientistsProjects(71271023,71210001) supported by the National Natural Science Foundation of ChinaProject(RCS2015ZZ003) supported by the Research Foundation of State Key Laboratory of Rail Traffic Control and Safety,Beijing Jiaotong University,China
文摘A model is proposed to describe the passengers’route choice behaviors in urban railway traffic with stochastic link capacity degradation by considering two types of demand,sensitive and insensitive passenger.The insensitive passengers choose their route without paying much attention to congestion.To the contrary,sensitive passengers who consider route congestion choose travel route based on generalized cost.An equilibrium state is given by variational inequalities in terms of travel generalized cost,which is represented by the combinations of mean and variance of total travel time.The diagonalization algorithm is given to solve this programming.Results show that insensitive passengers have large effects on the path choice than sensitive ones,especially for the larger demand.
文摘Dhaka, the capital city of Bangladesh is one of the most overpopulated city in the world and traffic jam is the most severe and regular affliction in the daily life. Also, the existing vehicles are not sufficient in compared to the population of the city. People have to spend many hours simply sitting in the traffic jam. This lessens the productivity of people and brings sufferings to them. Gulshan-Banani-HatirJheel area is the busiest regions within the city and face severe traffic jam during working hours. These lakes are totally unused. Therefore, there is a possibility to build a waterways network for passengers transport through these lakes. This will reduce the affliction of people via reducing traffic jam. The proposed transportation networks will also preserve the natural environment of the lakes and bring a source of entertainment in the city life. Many developed cities in the world like London, New York, Paris, Venice, Shanghai etc. already have implemented waterways network inside the city and successfully made the best use of cistern side.
文摘Ten years of financial stability in Brazilian economy have gone. In this period, the regional transportation of passengers suffered exogenous impacts: economical crises, airport crises and great proportions' accidents, as well as impacts which were intern to the system: institutional changes (liberation of tariff promotions, many companies establishing themselves and also coming to bankruptcy), creation of regulating institutions in the air transportation as well as the land transportation. Theoretically, it is expected that these changes have generated impacts in the demand for trips, since an environment regulated with more flexible prices and higher amounts of companies would generate a competitive environment in which the companies could struggle to attract their demand. On the other hand, the impacts which are exogenous to the system can generate responses in the sense of restoring the balance of demand. Thus, based on the theoretical experience, this article aims at analyzing empirically, through categorical variables, if there were impacts on the demand for regional trips in Brazil due to the internal or external changes. In order to perform this, monthly data from January, 1999 to December, 2009 are utilized and estimates are calculated making use of SUR (seemingly unrelated regressions). As a result, we have the meaning of the internal and external impacts related to air and land transports, identifying that the worldwide economic crisis generated an impact at the level of the demand for transportation and also that the flexibility of tariffs allowed by ANTT (Ag^ncia Nacional de Transportes Terrestres) had an equal impact on the demand for land transportation.
文摘A taxi company in Shanghai has announced its plan to equip half of its fleet - about 6,000 taxis - with digital video recorders by the end of the year. According to the company, there will be four cameras per taxi, installed internally as well as externally to ensure the safety of both passengers and drivers.
文摘Evacuated Tube Transport Technologies (ET3) offers the potential for more than an order of magnitude improvement in transportation efficiency, speed, cost, and effectiveness. An ET3 network may be optimized to sustainably displace most global transportation by car, ship, truck, train, and jet aircraft. To do this, ET3 standards should adhere to certain key principals: maximum value through efficiency, reliability, and simplicity; equal consideration for passenger and cargo loads; optimum size; high speed/high frequency operation; demand oriented; random accessibility; scalability; high granularity; automated control; full speed passive switching; open standards of implementation; and maximum use of existing capacities, materials, and processes.
基金supported by the Development Foundation of Shanghai Municipal Commission of Science and Technology (Grant No.072112007)the Shanghai Leading Acdemic Discipline Project (Grant No.J50104)
文摘An estimation approach is proposed in this paper based on the binocular stereovision to collect the degree of crowdedness in public transports. The proposed method combines the disparity with frame differences to extract the foreground object. An adaptive window normalized cross correlation (NCC) matching and interpolated method is applied to get the sub-pixel image disparity value. Then, the foreground object is projected to the horizontal plane to eliminate the influence of the occlusion and perspective effect. Finally the degree of crowdedness is calculated from the area and the perimeter of the foreground objects. Experimental results show that the proposed method can obtain good estimation results in the simulated scenes in the laboratory and on parking or moving buses. This approach is effective to illumination changes, shadows and occlusion of passengers.
文摘This paper describes two perspectives to improve the passenger experience.The passenger satisfaction pyramid is introduced,consisting of the base of the pyramid(dissatisfiers)focusing on time well saved and the top of the pyramid(satisfiers)aiming at time well spent.The challenge in planning and design of public transport services is to find the most efficient(set of)design choices.Depending on the context this might either mean focusing on the top or on the bottom of the pyramid.We found that influencing and enhancing the qualities of the satisfiers is far more important than traditional studies showed us.For stations,regression analyses show that dissatisfiers are responsible for explaining almost half of the total score of the station and satisfiers are responsible for the other half of the scores passengers give for the station.We still have to put a lot of energy in getting the basics right,starting in the planning phase,but then we are not allowed to lean back.We have to keep investing in qualities like ambience,comfort and experience which makes the customers truly happy at the end of the day.
文摘This study analyzes air passenger route choice behavior for long-haul inter-continental travel. It employs the SP (state preference) technique and logit modeling to investigate the impact of route development via neighboring countries in the region. With the Japanese government pursuing an increase in international routes at Haneda International Airport, and the Chinese government planning to construct Beijing Capital Second International Airport by 2019, the competition among airports to serve as hubs in Northeast Asia will increase significantly. Korean passengers will have a greater number of route choices when traveling to North America or Europe, utilizing not only direct flights from Incheon International Airport but also flights via Tokyo or Beijing area airports including Haneda International Airport, Narita International Airport, Beijing Capital International Airport and Beijing Capital Second International Airport. Accordingly, passengers will choose among the alternatives by considering fares and flight times. As such, it is essential for airports to offer flights with competitive prices for transit passengers to become successful competitive airports in the region. Therefore, it will become more important for market decision makers to strive toward more attractive ticket prices and better route network quality.
基金supported by the National Natural Science Foundation of China(Grant No.52102382)the Shanghai Science and Technology Committee(Grant No.20DZ1203201)+1 种基金the Fundamental Research Funds for the Central Universities(2022-5-YB-04)the Shanghai Shentong Metro Group Co.,Ltd.(Grant Nos.JSKY21R005-1-WT-21064 and JS-KY21R005-2).
文摘Periodic frequent pattern discovery is a non-trivial task to discover frequent patterns based on user interests using a periodicity measure.Although conventional algorithms for periodic frequent pattern detection have numerous applications,there is still little research on periodic frequent pattern detection of individual passengers in the metro.The travel behavior of individual passengers has complex spatio-temporal characteristics in the metro network,which may pose new challenges in discovering periodic frequent patterns of individual metro passengers and developing mining algorithms based on real-world smart card data.This study addresses these issues by proposing a novel pattern for metro passenger travel pattern called periodic frequent passenger traffic patterns with time granularities and station attributes(PFPTS).This discovered pattern can automatically capture the features of the temporal dimension(morning and evening peak hours,week)and the spatial dimension(entering and leaving stations).The corresponding complete mining algorithm with the PFPTS-tree structure has been developed.To evaluate the performance of PFPTS-tree,several experiments are conducted on one-year real-world smart card data collected by an automatic fare collection system in a certain large metro network.The results show that PFPTS-Tree is efficient and can discover numerous interesting periodic frequent patterns of metro passengers in the real-world dataset.
基金supported by the National Natural Science Foundation of China(No.52372332)the Fundamental Research Funds for the Central Universities of China(No.2022-5-YB-04)the Shanghai Shentong Metro Group Co.,Ltd.(Nos.JSKY21R005-1-WT-21064,and JS-KY22R033-2).
文摘Periodic pattern mining is of great significance for understanding passenger travel behav-ior,but the previous works mainly focused on the trajectory data and the dimension of the spot/point.Besides,many uncertain factors(severe weather,traffic accident,etc.)may interfere with discovering original and accurate periodic travel patterns.This paper pro-poses a novel type of travel pattern called motif periodic frequent pattern(MPFP),which captures the periodicity of network temporal motifs of individual metro passengers with higher-order spatio-temporal characteristics considering,uncertain disturbances.We also propose a new complete mining algorithm MPFP-growth to extract MPFP from smart card data(SCD),and apply the real long-time-span experimental data from a large-scale metro system is applied.Results show that frequent-travel metro passengers usually have some typical MPFPs with the temporal periodic characteristic of“week”.Only the top 10 types of all 4624 types account for about 95%of all motifs and the top 5 types constitute about 90%,and the MPFP of the top 3 types of motifs account for nearly 80%of all periodic patterns,in which Mono-MPFP and 2-MPFP are the main ones.The relatively stable time range of MPFP is three months,and the threshold for the optimal uncertain disturbance factor should be set at 5%.Additionally,several interesting typical MPFPs of individual metro commuting passengers and their proportions are introduced to further understand the multifarious variants of MPFP.
基金the National Social Science Fund of China(Grant No.21BGL296).
文摘This paper investigates the scale and expression of passengers’anger arising from disputes between drivers and passengers,and between passengers,by surveying a sample of 757 undergraduate students.The bus passengers’anger scale and expression inventory(BPASX),a newly-designed questionnaire battery,is used to analyse the anger levels and resulting behaviour expression of passengers in 6-item anger-provoking situations.The analysis shows that a positive correlation exists between the frequency or duration of bus rides and anger levels/external anger expression,while self-adaptive expression is only correlated with frequency.Gender differs only in the violent external expression,where males display a greater preference.Meanwhile,the correlations of anger levels between anger-provoking situations are significantly positive.Moreover,anger expression patterns gradually shift from self-adaptation to external expression as anger levels grow in general,but the variation rules of expression frequency are different.Overall,this study provides a newly effective tool to explore characteristics of the anger expression of bus passengers in different anger-provoking scenarios and demonstrates its variation features when anger levels change.
文摘This study uses multiple regression to investigate the effects of Land and building use on popuLation, Land price, and passengers. Initialty, we abstract annuat data on Land and buildings usage within a radius of 0 m-400 m for railway stations and 400 m-800 m for subway stations in Fukuoka, Japan by using the GIS. We then analyze the relationships between 13 factors of rand use and 8 factors of building usage, as well as the related poputation, Land price, and passengers using the quantitative expression method. Using several categories of land use and building usage as explanatory variables, we anatyze the degree to which the selected categories affect population, Land price, and passengers by using the muttiple regression method. This research can aid the further development of land and buitding usage in the future.
基金support through Manipal University Jaipur for the Enhanced Seed Grant under the Endowment Fund(Grant No.E3/2023-24/QE-04-05).
文摘Dear Editor,Lung cancer is a major global health concern,with 2.2 million patients diagnosed in 2020.Non-small cell lung cancer(NSCLC)accounts for 80%of these cases,primarily comprising two subtypes:lung adenocarcinoma(LUAD)and squamous cell carcinoma(LUSC)[1].Researchers use immunohisto-chemistry,next-generation sequencing,and single-cell RNA sequencing to study genetic alterations,tumor heterogeneity,and tumor microenvironments,aiming to identify potential therapeutic options for specific NSCLC subtypes[2].
文摘When you go somewhere,do you like to be the driver or a passenger?When you are the driver,you are in control.You can go fast or slow.You can pick the route.When and where do you stop?You decide.You enjoy the feeling of driving.Ifs fun!
文摘1 There was a taxi driver who was angry and wanted to finish his shift as soon as possible.When he arrived to pick up his last passenger of the day,he honked the horn(按喇叭),but no one came out of the apartment.Minutes later,he honked again,but still there was no reaction.