To demonstrate the feasibility and improve the implementation of laser weeding, a prototype robot was built and equipped with machine vision and gimbal mounted laser pointers. The robot consisted of a mobile platform modified from a small commercial quad bike, a camera to detect the crop and weeds and two steerable gimbals controlling the laser pointers. Visible class one laser pointers were used to simulate the power laser trajectories. A colour segmentation algorithm was utilised to extract plants from the soil background, size estimation was used to differentiate crop from weeds and an eroding and dilating algorithm was developed for objects that were touching. Conversely, another algorithm, which relied on shape descriptors, was able to distinguish plant species in non-touching status regardless of area difference. To reduce route length and run time, a new path-planning algorithm for static weeding was proposed and tested. It was demonstrated to be more temporally efficient especially when addressing higher density of weeds. A model to determine the optimal segmentation size based on time taken for treatment was established. It was found that the segmentation algorithm has the potential to be widely used in fast path-planning for the travelling-salesman problem. Finally, performance tests showed that the weeding mean error was 1.97 mm, with a 0.88 mm standard deviation. Another test indicated that with a laser traversal speed of 30 mm/s and a dwell time of 0.64 s per weed, it had a hit rate of 97%.

Background: Critical thinking (CT) is an essential competence for medical students. Family socioeconomic status (family SES) and general self-efficacy (GSE) play crucial roles in the development of CT. However, the association among family SES, GSE, and CT in Chinese medical students has yet to be fully investigated.Objectives: To investigate the role of family SES and GSE in the development of CT in Chinese medical students.Methods: 1,338 medical students were recruited using multistage stratified cluster sampling from three institutions in China. The Chinese critical thinking disposition inventory (CTDI-CV), General Self-Efficacy Scale (GSES), and a self-made inventory assessing family SES were administered to collect data. The relationship between CT and family SES as well as GSE was evaluated by structural equation modeling.Results: Students of higher family SES obtained higher CTDI-CV and GSES scores. A positive correlation was found between family SES and CT (r = 0.101–0.141, p < 0.05 or p < 0.01), as well as between family SES and GSE (r = 0.111–0.129, p < 0.01). Moreover, GSE was moderately correlated with CT (r = 0.418, p < 0.01). The model of partial mediate effect of GSE showed the best fit index with X2 = 29.698, df = 9 and X2/df = 3.300, NFI = 0.990, IFI = 0.993, TLI = 0.984, CFI = 0.993, RMSEA = 0.041.Conclusion: Family SES has a positive albeit limited influence on GSE and CT in Chinese medical students. GSE mediates the effect of family SES on CT and plays a larger role. Enhancing medical student’ GSE maybe an efficacious way to improve medical students’ CT.