BACKGROUND： Excitatory amino acids including glutamic acid and aspartic acid play a neurotrophic role during early development of the central nervous system but go on to promote toxic effects. Inhibitory amino acids ...BACKGROUND： Excitatory amino acids including glutamic acid and aspartic acid play a neurotrophic role during early development of the central nervous system but go on to promote toxic effects. Inhibitory amino acids include γ-aminobutyric acid and glycine. Changes in their concentration can reflect the degree of injury to brain tissue after cerebral infarction. OBJECTIVE： To investigate the effects of propofol on amino acid neurotransmitter levels and neuronal apoptosis in the hippocampus in a rat model of ischemia/reperfusion injury. DESIGN： Randomized controlled animal study. MATERIALS： Sixty male Wistar rats were randomly divided into a sham operation group, model group and propofol （50, 100 and 150 mg/kg） groups （n = 12）. METHODS： Global brain models of ischemia/reperfusion injury were established in the model group and the propofol groups. The vertebral artery and common carotid artery were merely isolated in the sham operation group. Ten minutes before ischemia, rats in the propofol groups were induced with an intraperitoneal injection of propofol （50, 100 or 150 mg/kg）; rats in the model and sham operation groups were induced with an intraperitoneal injection of saline （5 mL）. MAIN OUTCOME MEASURES： Content of amino acids, neuronal apoptotic index and density of apoptotic neurons in the hippocampal CA1 region. RESULTS： After a 10-minute ischemia / 60-minute reperfusion, the content of glutamic acid and aspartic acid was significantly decreased in the propofol （50, 100 and 150 mg/kg） groups compared with the model group （P 〈 0.05 or P 〈 0.01）; but the content of γ-aminobutyric acid was significantly increased in the propofol （100 and 150 mg/kg） groups （P 〈 0.05）. After a 72-hour reperfusion, the neuronal apoptotic index was significantly decreased in the propofol （50, 100 and 150 mg/kg） groups compared with the model group （P 〈 0.05 or P 〈 0.01 ）, and the decrease was remarkable in the propofol （100 and 150 mg/kg） groups. After a 72-hour reperfusion, neuronal apoptosis was not observed in the hippocampal CA1 region in the sham operation group, and the density of apoptotic neurons in the propofol （50, 100 and 150 mg/kg） groups showed a significantly dose-dependent decrease in the hippocampal CA1 region compared with the model group （P 〈 0.01）. CONCLUSION： Propofol can protect from brain ischemia/reperfusion injury. This is possibly related to inhibition of excitatory amino acid release, reduction in inhibitory amino acid consumption and decreasing neuronal apoptosis.展开更多
Background：As a major complication after orthotopic liver transplantation （OLT）,the occurrence of acute kidney injury （AKI） is frequently defined by serum creatinine （Cr）;however,the accuracy of commonly used b...Background：As a major complication after orthotopic liver transplantation （OLT）,the occurrence of acute kidney injury （AKI） is frequently defined by serum creatinine （Cr）;however,the accuracy of commonly used blood urea nitrogen （BUN）,uric acid （UA）,and β2-microglobulin （β2-MG） remains to be explored.This retrospective study compared the accuracy of these parameters for post-OLT AKI evaluation.Methods：Patients who underwent OLT in three centers between July 2003 and December 2013 were enrolled.The postoperative AKI group was diagnosed by the Kidney Disease Improving Global Outcomes （KDIGO） criteria and classified by stage.Measurement data were analyzed using the t-test or Wilcoxon rank-sum test;enumerated data were analyzed using the Chi-square test or Fisher＇s exact test.Diagnostic reliability and predictive accuracy were evaluated using receiver operating characteristic （ROC） curve analysis.Results：This study excluded 976 cases and analyzed 697 patients （578 men and 1 1 9 women）;the post-OLT AKI incidence was 0.409.Compared with the no-AKI group,the AKI group showed very significant differences in Model for End-stage Liver Disease score （14.74 ± 9.91 vs.11.07 ± 9.54,Z =5.404;P ＜ 0.001）,hepatic encephalopathy （45 [15.8％] vs.30 [7.3％],x2 =12.699;P ＜ 0.001）,hemofiltration （28 [9.8％] vs.0 [0.0％],x2 =42.171;P ＜ 0.001）,and 28-day mortality （23 [8.1％] vs.9 [2.2％],x2 13.323;P ＜0.001）.Moreover,mean values of Cr,BUN,UA,and β2-MG in the AKI group differed significantly at postoperative days 1,3,and 7 （all P ＜0.001）.ROC curve area was 0.847 of Cr for the detection of AKI Stage 1 （sensitivity 80.1％,specificity 75.7％,cutoffvalue 88.23 μmol/L）,0.916 for Stage 2 （sensitivity 87.6％,specificity 82.6％,cutoff value 99.9 μmol/L）,and 0.972 for Stage 3 （sensitivity 94.1％,specificity 88.2％,cutoff value 122.90 μmol/L）.Conclusion：The sensitivity and specificity of serum Cr might be a high-value indicator for the diagnosis and grading of post-OLT AKI.展开更多
a-Synuclein is a soluble monomer abundant in the central nervous system. Aggregates of a-synuclein,consisting of higher-level oligomers and insoluble fibrils,have been observed in many chronic neurological diseases an...a-Synuclein is a soluble monomer abundant in the central nervous system. Aggregates of a-synuclein,consisting of higher-level oligomers and insoluble fibrils,have been observed in many chronic neurological diseases and are implicated in neurotoxicity and neurodegeneration.a-Synuclein has recently been shown to aggregate following acute ischemic stroke, exacerbating neuronal damage.Propofol is an intravenous anesthetic that is commonly used during intravascular embolectomy following acute ischemic stroke. While propofol has demonstrated neuroprotective properties following brain injury, the mechanism of protection in the setting of ischemic stroke is unclear. In this study, propofol administration significantly reduced the neurotoxic aggregation of a-synuclein, decreased the infarct area, and attenuated the neurological deficits after ischemic stroke in a mouse model. We then demonstrated that the propofol-induced reduction of a-synuclein aggregation was associated with increased mammalian target of rapamycin/ribosomal protein S6 kinase beta-1 signaling pathway activity and reduction of the excessive autophagy occurring after acute ischemic stroke.展开更多
Background：In this prospective randomized study,we compared the predicted blood and effect-site C50 for propofol and remifentanil target-controlled infusion （TCI） and the bispectral index （BIS） values at loss of ...Background：In this prospective randomized study,we compared the predicted blood and effect-site C50 for propofol and remifentanil target-controlled infusion （TCI） and the bispectral index （BIS） values at loss of consciousness （LOC） and response to a standard noxious painful stimulus （LOS） in elderly and young patients,respectively.We hypothesized that the elderly patients will require lower target concentration of both propofol and remifentanil at above two clinical end-points.Methods：There were 80 American Society of Anesthesiologists （ASA） physical status Ⅰ Ⅱ unpremedicated patients enrolled in this study,they were divided into elderly group （age ≥65 years,n =40） and young group （aged 18-54 years,n =40）.Propofol was initially given to a predicted blood concentration of 1.2 μg/ml and thereafter increased by 0.3 μg/ml every 30 s until Observer＇s Assessment of Alertness and Sedation score was 1.The propofol level was kept constant,and remifentanil was given to provide a predict blood concentration of 2.0 ng/ml,and then increased by 0.3 ng/ml every 30 s until loss of response to a tetanic stimulus.BIS （version 3.22,BIS Quattro sensor） was also recorded.Results：In elderly group,the propofol effect-site C50 at LOC of was 1.5 （1.4-1.6） μg/ml,was significantly lower than that of young group,which was 2.2 （2.1-2.3） μg/ml,the remifentanil effect-site C50 at LOS was 3.5 （3.3-3.7） ng/ml in elderly patients,was similar with 3.7 （3.6-3.8） ng/ml in young patients.Fifty percent of patients lost consciousness at a BIS value of 57.3 （56.4-58.1）,was similar with that of young group,which was 55.2 （54.0-56.3）.Conclusion：In elderly patients,the predicted blood and effect-site concentrations of propofol at LOC were lower than that of young patients.At same sedation status,predicted blood and effect-site concentrations of remifentanil required at LOS were similar in elderly and young patients.BIS were not affected by age.Low-propofol/high-opioid may be optional TCI strategy for elderly patients.展开更多
Background： Bispectral index （BIS） is considered very useful to guide anesthesia care in elderly patients, but its use is controversial for the evaluation of the adequacy of analgesia.This study compared the BIS ch...Background： Bispectral index （BIS） is considered very useful to guide anesthesia care in elderly patients, but its use is controversial for the evaluation of the adequacy of analgesia.This study compared the BIS changes in response to loss of consciousness （LOC） and loss of somatic response （LOS） to nociceptive stimuli between elderly and young patients receiving intravenous target-controlled infusion （TCI） of propofol and remifentanil.Methods： This study was performed on 52 elderly patients （aged 65-78 years） and 52 young patients （aged 25-58 years）, American Society of Anesthesiologists physical status Ⅰ or Ⅱ.Anesthesia was induced with propofol administered by TCI.A standardized noxious electrical stimulus （transcutaneous electrical nerve stimulation, [TENS]） was applied （50 Hz, 80 mA, 0.25 ms pulses for 4 s） to the ulnar nerve at increasing remifentanil predicted effective-site concentration （Ce） until patients lost somatic response to TENS.Changes in awake, prestimulus, poststimulus BIS, heart rate, mean arterial pressure, pulse oxygen saturation, predicted plasma concentration, Ce of propofol, and remifentanil at both LOC and LOS clinical points were investigated.Results： BISLOC in elderly group was higher than that in young patient group （65.4 ＆#177; 9.7 vs.57.6 ＆#177; 12.3） （t =21.58, P 〈 0.0001） after TCI propofol, and the propofol Ce at LOC was 1.6 ＆#177; 0.3 μg/ml in elderly patients, which was significantly lower than that in young patients （2.3 ＆#177; 0.5 μg/ml） （t =7.474, P 〈 0.0001）.As nociceptive stimulation induced BIS to increase, the mean of BIS maximum values after TENS was significantly higher than that before TENS in both age groups （t =8.902 and t =8.019, P 〈 0.0001）.With increasing Ce of remifentanil until patients lost somatic response to TENS, BISLOS was the same as the BISLOC in elderly patients （65.6 ＆#177; 10.7 vs.65.4 ＆#177; 9.7）, and there were no marked differences between elderly and young patient groups in BISawake, BISLOS, and Ce of remifentanil required for LOS.Conclusion： In elderly patients, BIS can be used as an indicator for hypnotic-analgesic balance and be helpful to guide the optimal administration of propofol and remifentanil individually.展开更多
Global Positioning System(GPS) trajectory data can be used to infer transportation modes at certain times and locations. Such data have important applications in many transportation research fields, for instance,to de...Global Positioning System(GPS) trajectory data can be used to infer transportation modes at certain times and locations. Such data have important applications in many transportation research fields, for instance,to detect the movement mode of travelers, calculate traffic flow in an area, and predict the traffic flow at a certain time in the future. In this paper, we propose a novel method to infer transportation modes from GPS trajectory data and Geographic Information System(GIS) information. This method is based on feature extraction and machine learning classification algorithms. While using GIS information to improve inference accuracy, we ensure that the algorithm is simple and easy to use on mobile devices. Applied to GeoLife GPS trajectory dataset, our method achieves 91.1% accuracy while inferring transportation modes, such as walking, bike, bus, car, and subway, with random forest classification algorithm. GIS features in our method improved the overall accuracy by 2.5% while raising the recall of the bus and subway transportation mode categories by 3.4% and 18.5%. We believe that many algorithms used in detecting the transportation modes from GPS trajectory data that do not utilize GIS information can improve their inference accuracy by using our GIS features, with a slight increase in the consumption of data storage and computing resources.展开更多
Research into the impact of road accidents on drivers is essential to effective post-crash interventions.However,due to limited data and resources,the current research focus is mainly on those who have suffered severe...Research into the impact of road accidents on drivers is essential to effective post-crash interventions.However,due to limited data and resources,the current research focus is mainly on those who have suffered severe injuries.In this paper,we propose a novel approach to examining the impact that being involved in a crash has on drivers by using traffic surveillance data.In traffic video surveillance systems,the locations of vehicles at different moments in time are captured and their headway,which is an important indicator of driving behavior,can be calculated from this information.It was found that there was a sudden increase in headway when drivers return to the road after being involved in a crash,but that the headway returned to its pre-crash level over time.We further analyzed the duration of the decay using a Cox proportional hazards regression model,which revealed many significant factors(related to the driver,vehicle,and nature of the accident)behind the survival time of the increased headway.Our approach is able to reveal the crash impact on drivers in a convenient and economical way.It can enhance the understanding of the impact of a crash on drivers,and help to devise more effective re-education programs and other interventions to encourage drivers who are involved in crashes to drive more safely in the future.展开更多
基金supported by the National Natural Science Foundation of China(Nos.U1804146,51905153,52111530068)the Science and Technology Innovation Team of Henan University of Science and Technology,China(No.2015XTD006)Major Science and Technology Project of Henan Province,China(No.221100230200)。
文摘BACKGROUND： Excitatory amino acids including glutamic acid and aspartic acid play a neurotrophic role during early development of the central nervous system but go on to promote toxic effects. Inhibitory amino acids include γ-aminobutyric acid and glycine. Changes in their concentration can reflect the degree of injury to brain tissue after cerebral infarction. OBJECTIVE： To investigate the effects of propofol on amino acid neurotransmitter levels and neuronal apoptosis in the hippocampus in a rat model of ischemia/reperfusion injury. DESIGN： Randomized controlled animal study. MATERIALS： Sixty male Wistar rats were randomly divided into a sham operation group, model group and propofol （50, 100 and 150 mg/kg） groups （n = 12）. METHODS： Global brain models of ischemia/reperfusion injury were established in the model group and the propofol groups. The vertebral artery and common carotid artery were merely isolated in the sham operation group. Ten minutes before ischemia, rats in the propofol groups were induced with an intraperitoneal injection of propofol （50, 100 or 150 mg/kg）; rats in the model and sham operation groups were induced with an intraperitoneal injection of saline （5 mL）. MAIN OUTCOME MEASURES： Content of amino acids, neuronal apoptotic index and density of apoptotic neurons in the hippocampal CA1 region. RESULTS： After a 10-minute ischemia / 60-minute reperfusion, the content of glutamic acid and aspartic acid was significantly decreased in the propofol （50, 100 and 150 mg/kg） groups compared with the model group （P 〈 0.05 or P 〈 0.01）; but the content of γ-aminobutyric acid was significantly increased in the propofol （100 and 150 mg/kg） groups （P 〈 0.05）. After a 72-hour reperfusion, the neuronal apoptotic index was significantly decreased in the propofol （50, 100 and 150 mg/kg） groups compared with the model group （P 〈 0.05 or P 〈 0.01 ）, and the decrease was remarkable in the propofol （100 and 150 mg/kg） groups. After a 72-hour reperfusion, neuronal apoptosis was not observed in the hippocampal CA1 region in the sham operation group, and the density of apoptotic neurons in the propofol （50, 100 and 150 mg/kg） groups showed a significantly dose-dependent decrease in the hippocampal CA1 region compared with the model group （P 〈 0.01）. CONCLUSION： Propofol can protect from brain ischemia/reperfusion injury. This is possibly related to inhibition of excitatory amino acid release, reduction in inhibitory amino acid consumption and decreasing neuronal apoptosis.
文摘Background：As a major complication after orthotopic liver transplantation （OLT）,the occurrence of acute kidney injury （AKI） is frequently defined by serum creatinine （Cr）;however,the accuracy of commonly used blood urea nitrogen （BUN）,uric acid （UA）,and β2-microglobulin （β2-MG） remains to be explored.This retrospective study compared the accuracy of these parameters for post-OLT AKI evaluation.Methods：Patients who underwent OLT in three centers between July 2003 and December 2013 were enrolled.The postoperative AKI group was diagnosed by the Kidney Disease Improving Global Outcomes （KDIGO） criteria and classified by stage.Measurement data were analyzed using the t-test or Wilcoxon rank-sum test;enumerated data were analyzed using the Chi-square test or Fisher＇s exact test.Diagnostic reliability and predictive accuracy were evaluated using receiver operating characteristic （ROC） curve analysis.Results：This study excluded 976 cases and analyzed 697 patients （578 men and 1 1 9 women）;the post-OLT AKI incidence was 0.409.Compared with the no-AKI group,the AKI group showed very significant differences in Model for End-stage Liver Disease score （14.74 ± 9.91 vs.11.07 ± 9.54,Z =5.404;P ＜ 0.001）,hepatic encephalopathy （45 [15.8％] vs.30 [7.3％],x2 =12.699;P ＜ 0.001）,hemofiltration （28 [9.8％] vs.0 [0.0％],x2 =42.171;P ＜ 0.001）,and 28-day mortality （23 [8.1％] vs.9 [2.2％],x2 13.323;P ＜0.001）.Moreover,mean values of Cr,BUN,UA,and β2-MG in the AKI group differed significantly at postoperative days 1,3,and 7 （all P ＜0.001）.ROC curve area was 0.847 of Cr for the detection of AKI Stage 1 （sensitivity 80.1％,specificity 75.7％,cutoffvalue 88.23 μmol/L）,0.916 for Stage 2 （sensitivity 87.6％,specificity 82.6％,cutoff value 99.9 μmol/L）,and 0.972 for Stage 3 （sensitivity 94.1％,specificity 88.2％,cutoff value 122.90 μmol/L）.Conclusion：The sensitivity and specificity of serum Cr might be a high-value indicator for the diagnosis and grading of post-OLT AKI.
基金the National Natural Science Foundation of China(81771139)the Beijing Natural Science Foundation(7194270).
文摘a-Synuclein is a soluble monomer abundant in the central nervous system. Aggregates of a-synuclein,consisting of higher-level oligomers and insoluble fibrils,have been observed in many chronic neurological diseases and are implicated in neurotoxicity and neurodegeneration.a-Synuclein has recently been shown to aggregate following acute ischemic stroke, exacerbating neuronal damage.Propofol is an intravenous anesthetic that is commonly used during intravascular embolectomy following acute ischemic stroke. While propofol has demonstrated neuroprotective properties following brain injury, the mechanism of protection in the setting of ischemic stroke is unclear. In this study, propofol administration significantly reduced the neurotoxic aggregation of a-synuclein, decreased the infarct area, and attenuated the neurological deficits after ischemic stroke in a mouse model. We then demonstrated that the propofol-induced reduction of a-synuclein aggregation was associated with increased mammalian target of rapamycin/ribosomal protein S6 kinase beta-1 signaling pathway activity and reduction of the excessive autophagy occurring after acute ischemic stroke.
文摘Background：In this prospective randomized study,we compared the predicted blood and effect-site C50 for propofol and remifentanil target-controlled infusion （TCI） and the bispectral index （BIS） values at loss of consciousness （LOC） and response to a standard noxious painful stimulus （LOS） in elderly and young patients,respectively.We hypothesized that the elderly patients will require lower target concentration of both propofol and remifentanil at above two clinical end-points.Methods：There were 80 American Society of Anesthesiologists （ASA） physical status Ⅰ Ⅱ unpremedicated patients enrolled in this study,they were divided into elderly group （age ≥65 years,n =40） and young group （aged 18-54 years,n =40）.Propofol was initially given to a predicted blood concentration of 1.2 μg/ml and thereafter increased by 0.3 μg/ml every 30 s until Observer＇s Assessment of Alertness and Sedation score was 1.The propofol level was kept constant,and remifentanil was given to provide a predict blood concentration of 2.0 ng/ml,and then increased by 0.3 ng/ml every 30 s until loss of response to a tetanic stimulus.BIS （version 3.22,BIS Quattro sensor） was also recorded.Results：In elderly group,the propofol effect-site C50 at LOC of was 1.5 （1.4-1.6） μg/ml,was significantly lower than that of young group,which was 2.2 （2.1-2.3） μg/ml,the remifentanil effect-site C50 at LOS was 3.5 （3.3-3.7） ng/ml in elderly patients,was similar with 3.7 （3.6-3.8） ng/ml in young patients.Fifty percent of patients lost consciousness at a BIS value of 57.3 （56.4-58.1）,was similar with that of young group,which was 55.2 （54.0-56.3）.Conclusion：In elderly patients,the predicted blood and effect-site concentrations of propofol at LOC were lower than that of young patients.At same sedation status,predicted blood and effect-site concentrations of remifentanil required at LOS were similar in elderly and young patients.BIS were not affected by age.Low-propofol/high-opioid may be optional TCI strategy for elderly patients.
文摘Background： Bispectral index （BIS） is considered very useful to guide anesthesia care in elderly patients, but its use is controversial for the evaluation of the adequacy of analgesia.This study compared the BIS changes in response to loss of consciousness （LOC） and loss of somatic response （LOS） to nociceptive stimuli between elderly and young patients receiving intravenous target-controlled infusion （TCI） of propofol and remifentanil.Methods： This study was performed on 52 elderly patients （aged 65-78 years） and 52 young patients （aged 25-58 years）, American Society of Anesthesiologists physical status Ⅰ or Ⅱ.Anesthesia was induced with propofol administered by TCI.A standardized noxious electrical stimulus （transcutaneous electrical nerve stimulation, [TENS]） was applied （50 Hz, 80 mA, 0.25 ms pulses for 4 s） to the ulnar nerve at increasing remifentanil predicted effective-site concentration （Ce） until patients lost somatic response to TENS.Changes in awake, prestimulus, poststimulus BIS, heart rate, mean arterial pressure, pulse oxygen saturation, predicted plasma concentration, Ce of propofol, and remifentanil at both LOC and LOS clinical points were investigated.Results： BISLOC in elderly group was higher than that in young patient group （65.4 ＆#177; 9.7 vs.57.6 ＆#177; 12.3） （t =21.58, P 〈 0.0001） after TCI propofol, and the propofol Ce at LOC was 1.6 ＆#177; 0.3 μg/ml in elderly patients, which was significantly lower than that in young patients （2.3 ＆#177; 0.5 μg/ml） （t =7.474, P 〈 0.0001）.As nociceptive stimulation induced BIS to increase, the mean of BIS maximum values after TENS was significantly higher than that before TENS in both age groups （t =8.902 and t =8.019, P 〈 0.0001）.With increasing Ce of remifentanil until patients lost somatic response to TENS, BISLOS was the same as the BISLOC in elderly patients （65.6 ＆#177; 10.7 vs.65.4 ＆#177; 9.7）, and there were no marked differences between elderly and young patient groups in BISawake, BISLOS, and Ce of remifentanil required for LOS.Conclusion： In elderly patients, BIS can be used as an indicator for hypnotic-analgesic balance and be helpful to guide the optimal administration of propofol and remifentanil individually.
基金supported in part by the National Key Basic Research and Development Program of China(No. 2017YFC0820502)the Directorof National Engineering Laboratory for Public Safety Risk Perception and Control by Big Data (PSRPC)the National Natural Science Foundation of China (No.61673233)。
文摘Global Positioning System(GPS) trajectory data can be used to infer transportation modes at certain times and locations. Such data have important applications in many transportation research fields, for instance,to detect the movement mode of travelers, calculate traffic flow in an area, and predict the traffic flow at a certain time in the future. In this paper, we propose a novel method to infer transportation modes from GPS trajectory data and Geographic Information System(GIS) information. This method is based on feature extraction and machine learning classification algorithms. While using GIS information to improve inference accuracy, we ensure that the algorithm is simple and easy to use on mobile devices. Applied to GeoLife GPS trajectory dataset, our method achieves 91.1% accuracy while inferring transportation modes, such as walking, bike, bus, car, and subway, with random forest classification algorithm. GIS features in our method improved the overall accuracy by 2.5% while raising the recall of the bus and subway transportation mode categories by 3.4% and 18.5%. We believe that many algorithms used in detecting the transportation modes from GPS trajectory data that do not utilize GIS information can improve their inference accuracy by using our GIS features, with a slight increase in the consumption of data storage and computing resources.
基金supported by the National Natural Science Foundation of China(No.71671100)the Joint Research Scheme of the National Natural Science Foundation of China/Research Grants Council of Hong Kong(Nos.71561167001 and N HKU707)+1 种基金the Director Foundation Project of National Engineering Laboratory for Public Safety Risk Perception and Control by Big Data(PSRPC)the Research Funds of Tsinghua University(No.20151080412).
文摘Research into the impact of road accidents on drivers is essential to effective post-crash interventions.However,due to limited data and resources,the current research focus is mainly on those who have suffered severe injuries.In this paper,we propose a novel approach to examining the impact that being involved in a crash has on drivers by using traffic surveillance data.In traffic video surveillance systems,the locations of vehicles at different moments in time are captured and their headway,which is an important indicator of driving behavior,can be calculated from this information.It was found that there was a sudden increase in headway when drivers return to the road after being involved in a crash,but that the headway returned to its pre-crash level over time.We further analyzed the duration of the decay using a Cox proportional hazards regression model,which revealed many significant factors(related to the driver,vehicle,and nature of the accident)behind the survival time of the increased headway.Our approach is able to reveal the crash impact on drivers in a convenient and economical way.It can enhance the understanding of the impact of a crash on drivers,and help to devise more effective re-education programs and other interventions to encourage drivers who are involved in crashes to drive more safely in the future.
