MPP: A Novel Algorithm for Estimating Vehicle Space Headways from a Single Image

Vehicle space headway, also called spacing, is an important and basic traffic parameter. Traditional space headway calculation methods are facing the problems of large errors and high costs. This paper presents a novel algorithm based on measurement point pairs (MPPs) to estimate the real-time microcosmic vehicle space headway from single images in existing traffic surveillance videos and images without any additional equipment. First, the camera is calibrated with road markings to obtain the relationship between the image coordinates and the world coordinates. Second, vehicle pairs of two successive vehicles in the image are established, measurement points on each vehicle are selected by video intelligence analysis technologies, and their world coordinates are calculated by camera calibration results. Finally, the measurement points of the preceding and following vehicles are matched to obtain the MPPs, followed by the calculation of the weighted space headway. By using the measurement point information, one of the most difficult problems in image distance measurement, the lack of height information, is solved. The main factors causing estimation errors are fully addressed and the range and trend of errors under certain conditions are given by virtual simulation. Two real-world experiments are used to prove the accuracy and usability of the MPP in common video scenes: the simulation experiment indicates that the MPP algorithm achieves a high accuracy with estimation error less than ±0.1 m and the relative error within 1.1%; the application experiment shows that the MPP-based calculation is more accurate and stable than the state-of-the-art distance measurement algorithm and that the convenience of the proposed MPP algorithm is higher than that of traditional methods of space headway estimation. Document type: Articl

Effect of CYP2C9 and VKORC1 genetic polymorphisms on warfarin dose requirement in Central China Han populations

Purpose: To investigate the frequency of CYP2C9 and vitamin K epoxide reductase complex subunit 1 (VKORC1) and determine the effect of these genetic factors on weekly warfarin dose requirement in Central China Han populations.Methods: A total of 333 hospitalized patients with deep venous thrombosis after minimally invasive surgery were enrolled in this study. Genotypes of VKORC1 and CYP2C9 were analyzed by polymerase chain reaction (PCR)-DNA Chip method. Multiple linear regression analysis was used to explore the impact on weekly warfarin dose requirement.Results: The allele frequencies of VKORC1 -1639 G and VKORC1 -1639 A were 0.105 and 0.895, respectively, whereas no genotype of CYP2C9*1*2, CYP2C9*2*2 and CYP2C9*3*3 were found, and the allele frequencies of CYP2C9*1, CYP2C9*2 and CYP2C9*3 were 0.943, 0.015 and 0.042, respectively. Multiple linear regression analysis indicated that several factors including VKORC1 -1639 G>A, CYP2C9*2, CYP2C9*3, age, body mass index (BMI) and amiodarone use may explain the 47.2 % of individual variations in the weekly warfarin doses requirement.Conclusion: There is no significant difference in the frequency of VKORC1 (-1639 G>A), CYP2C9*2 and CYP2C9*3 compared to those of Asian populations, but there is significant difference when compared with those of Europeans and Caucasians. Considering VKORC1 -1639 G>A, CYP2C9*2, and CYP2C9*3 genetic polymorphisms as well as age, BMI and amiodarone use may explain the 47.2% of individual variations in the weekly warfarin doses requirement..Keywords: Warfarin, CYP2C9, VKORC1, Polymorphism, Body mass index, International normalized rati