Path tracking control of autonomous agricultural mobile robots

In a tractor automatic navigation system, path planning plays a significant role in improving operation efficiency. This study aims to create a suboptimal reference course for headland turning of a robot tractor and design a path-tracking controller to guide the robot tractor along the reference course. A time-minimum suboptimal control method was used to generate the reference turning course based on the mechanical parameters of the test tractor. A path-tracking controller consisting of both feedforward and feedback component elements was also proposed. The feedforward component was directly determined by the desired steering angle of the current navigation point on the reference course, whereas the feedback component was derived from the designed optimal controller. Computer simulation and field tests were performed to validate the path-tracking performance. Field test results indicated that the robot tractor followed the reference courses precisely on flat meadow, with average and standard lateral devia- tions being 0.031 m and 0.086 m, respectively. However, the tracking error increased while operating on sloping meadow due to the employed vehicle kinematic model.     

Students’ perceptions of a marine education program at a junior high school in Japan with a specific focus on Satoumi

In many coastal areas of Japan, local fishermen manage fish and other marine resources in a sustainable manner. Such areas are referred to as Satoumi. In this study, we focused on Hinase Junior High School in Okayama Prefecture, Japan, which is implementing a proactive marine education program in collaboration with local fishermen to maintain Satoumi. We conducted semi-structured interviews with the students (n = 108; thirty-six students in each grade [seventh-, eighth-, and ninth-graders]) at Hinase Junior High School. Using the grounded theory, we identified students’ perceptions of this program as well as of the sea. The results revealed that the program appears to have changed students’ perceptions, such as recognizing the importance of the sea and eelgrass as well as their behavior such that they no longer throw waste into the sea. The higher the grade level was, the more that students felt close to and were willing to care for the sea. Our study suggests that the program has helped to develop individuals who are knowledgeable about the fishing community of Hinase, fishermen’s roles, and activities that would contribute to biodiversity conservation and who are motivated to conserve Satoumi in the future.     

Microfluidic devices for studying heterotypic cell-cell interactions and tissue specimen cultures under controlled microenvironments

Microfluidic devices allow for precise control of the cellular and noncellular microenvironment at physiologically relevant length- and time-scales. These devices have been shown to mimic the complex in vivo microenvironment better than conventional in vitro assays, and allow real-time monitoring of homotypic or heterotypic cellular interactions. Microfluidic culture platforms enable new assay designs for culturing multiple different cell populations and∕or tissue specimens under controlled user-defined conditions. Applications include fundamental studies of cell population behaviors, high-throughput drug screening, and tissue engineering. In this review, we summarize recent developments in this field along with studies of heterotypic cell-cell interactions and tissue specimen culture in microfluidic devices from our own laboratory.     

Surface plasmon resonance analysis to evaluate the importance of heparin sulfate groups' binding with human aFGF and bFGF

Human acidic and basic fibroblast growth factors (aFGF and bFGF) are classic and well characterized members of the heparin-binding growth factor family. Heparin is generally thought to play an extremely important role in regulating aFGF and bFGF bioactivities through its strong binding with them. In order to unravel the mechanism of the interactions between heparin and FGFs, and evaluate the importance of heparin sulfate groups' binding with FGFs, surface plasmon resonance analyses were performed using IAsys Cuvettes System. Heparin and its regioselectively desulfated derivatives were immobilized on the cuvettes. aFGF and bFGF solutions with different concentrations were pipetted into the cuvettes and the progress of the interaction was monitored in real-time by Windows-based software, yielding kinetic and equilibrium constants for these interactions. In addition, in order to reduce the delicate difference among the cuvettes, inhibition analyses of mixtures of FGFs and immobilized native heparin by modified heparins were also done. The data from these two methods were similar, indicating that all sulfate groups at 2-O, 6-O and N- in heparin were required for the binding to aFGF; and that their contribution to the binding was in the order 2-O, N- and 6-O-sulfate group. In contrast, definite contribution of the 6-O-sulfate group to the binding with bFGF was most apparent, while the other two sulfate groups appeared to be necessary in the order 2-O and N-sulfate group. These methods established here can be used for analysing the effect of sulfate groups in heparin on the binding with other human FGF members or other heparin-binding proteins. The project supported by the Scientific Research Foundation for Returned Overseas Chinese Scholars, State Education Ministry of China and Zhejiang Provincial Natural Science Foundation of China (301306)     

Classification of children with learning problems and the establishment of special classes in Delaware from the 1930s to the mid-1940s

ABSTRACT

This study focuses on J. E. Wallace Wallin, who recognised the rights of children with disabilities to receive an education, and who tackled the scientific classification of children and the provision of special classes in the state of Delaware from the 1930s to the middle of the 1940s. This study intends to clarify how Wallin recognised and classified children who exhibited learning problems, and how he provided an educational environment for them. Wallin advocated the democratic philosophy of providing differentiated education based on the individual differences among children. He classified children with learning problems as “mentally deficient”, “backward”, and “special subject-matter disabilities”. He also recommended special educational treatment in not only special classes but also regular classes. He insisted that regular class teachers and special class teachers share the responsibility of educating children with disabilities. However, in addition to tailoring education based on the diversity exhibited by children with learning problems, it is essential to tailor it for disabled children in public school special classes established in their communities. In terms of both human and material resources, it was difficult to address learning problems suitably in regular classes while improving the quality and quantity of education in special classes.