Aim: We identified four cases of infection with hepatitis B virus genotype G and A2 recombinant (HBV/G/A2) strains, which were initially overlooked by enzyme immunoassay-based genotyping. The patients were all men who have sex with men (MSM) and inhabited several metropolitan areas of Japan, suggesting that the recombinant strains may be circulating among high-risk groups such as MSM. Here, we investigated the genomic structure and virological properties of the HBV/G/A2 strains.Methods: Complete genome sequences of the isolates were determined and phylogenetically analyzed. Replication efficiency of HBV/G/A2 was investigated by transfecting plasmids containing 1.24-fold viral genome. The in vivo viral kinetics of HBV/G/A2 were investigated using chimeric mice with humanized livers.Results: Phylogenetic analysis revealed that the four strains were almost identical (> 99.7% homologous). The preS2/S region of these strains was highly homologous to that of genotype A2 and the remaining region was almost identical to that of genotype G, reflecting inter-genotypic recombination. Interestingly, in all four cases, genotype A was co-infected as a minor population. In vitro analysis revealed that HBV/G/A2 had a low replication rate. Although detectable viremia was not measurable following the inoculation of HBV/G/A2 into chimericmice, subsequent superinfection of HBV genotype A greatly enhanced HBV/G/A2 replication and viral spread.Conclusion: We found that four cases of HBV/G/A2 recombinant among MSM patients in the metropolitan areas of Japan, and HBV/A co-infections are required for its efficient replication. High-risk groups such as MSM should be carefully tested for infection of genotype G-derived variants.

We have been conducting research on ways to contribute to reducing the workload of caregivers. We developed a wheelchair capable of following a single accompanying caregiver in a parallel position. However, observations in actual care facilities revealed that people often move as a group: for instance, two caregivers each pushed a wheelchair together. Therefore, we now aim to develop a robotic wheelchair system that allows multiple wheelchairs and accompanying caregivers to coordinate their movement together. However, such a situation necessitates a complex system. Making such a system practical represents an enormous challenge. Therefore, as a first step we decided to break down this complex “multiple-multiple” situation by isolating particular instances with multiple wheelchairs and/or multiple caregivers. In this paper, we focus on the “single-multiple” situation; i.e., a situation where a single wheelchair user is accompanied by multiple accompanies. We propose a robotic wheelchair system that facilitates coordinated movement between the wheelchair and the caregivers. In other words, the wheelchair system will track multiple people in the vicinity using GPGPU, and distinguish the accompanying caregivers from among other passersby based on the trajectory of the individuals' movement.

In recent years, there has been an increasing demand for elderly care in Japan due to the problems posed by a declining birthrate and an aging population. To deal with the problem, we aim to develop a multiple wheelchair robot system that moves with multiple companions collaboratively. In actual care, we noticed that for a group of four people, which included wheelchair users and their companions they tended to break up into two sets of two (1 wheelchair user and 1 caregiver) to move around or communicate with each other. Based on this observation, we propose a robotic wheelchair system that facilitates coordinated movement between the wheelchairs and the companions while maintaining suitable formations for communication among the group.

In order to reduce the burden of caregivers facing an increased demand for care, particularly for the elderly, we developed a system whereby multiple robotic wheelchairs can automatically move alongside a companion. This enables a small number of people to assist a substantially larger number of wheelchair users effectively. This system utilizes an environmental map and an estimation of position to accurately identify the positional relations among the caregiver (or a companion) and each wheelchair. The wheelchairs are consequently able to follow along even if the caregiver cannot be directly recognized. Moreover, the system is able to establish and maintain appropriate positional relations.

We introduce a robotic wheelchair that can move with a companion collaboratively to facilitate easy communication between them. The system uses the Laser Range Sensor attached horizontally on the companion’s shoulder level for observing the companion’s position to follow him/her. The system tracks the companion’s position and orientation to move with the companion and to avoid collision with him/her. Keywords— Robotic wheelchair, human tracking, laser range

Although it is desirable for wheelchair users to go out alone by operating wheelchairs on their own, they are often accompanied by caregivers or companions. In designing robotic wheelchairs, therefore, it is important to consider not only how to assist the wheelchair user but also how to reduce companions' load and support their activities. We specially focus on the communications among wheelchair users and companions because the face-to-face communication is known to be effective to ameliorate elderly mental health. Hence, we proposed a robotic wheelchair able to move alongside a companion. We demonstrate our robotic wheelchair. All attendees can try to ride and control our robotic wheelchair.

The electro-mechanical simulator is developed. The simulator includes variable speed synchronous generator model and hydro-power plant water column model. The both models are developed using well established method. The synchronous generator model is formulated on d-q axis as an induction generator with rotor windings. The parameters are set according to typical hydro-power generators. The water hammer model is formulated by the method of characteristics, because of the simulation easiness. The hydro-turbine is modeled as an orifice whose resistance is inverse proportional to the turbine rotation speed. The pump characteristics are modeled as a centrifugal pump. The coupling phenomena of the generator and mechanical effects can be analyzed by the simulator. It will help us the control strategy design of variable speed hydro-turbine for power system stabilization.

Although it is desirable for wheelchair users to move alone by operating wheelchairs themselves, they are often pushed or accompanied by caregivers, especially in elderly care facilities. In designing robotic wheelchairs, therefore, it is important to consider how to reduce the caregiver's load and support their activities. We particularly focus on communication among wheelchair users and caregivers because face-to-face communication is known to be effective in ameliorating elderly mental health issues. Hence, we propose a maneuverable robotic wheelchair that can move autonomously towards a goal while considering the situation of the accompanying caregiver. Our robotic wheelchair starts to move autonomously towards the goal as soon as the caregiver sets the goal position, such as a bathroom, by utilizing its touch panel interface. While moving towards the goal, the robotic wheelchair autonomously controls its speed and direction of movement to facilitate natural communication between the wheelchair user and the caregiver, by observing the situation of the accompanying caregiver.

The Stipsicz conjecture on the fiber-sum decomposability of Lefschetz fibrations states that nonminimal Lefschetz fibrations over S-2 are irreducible with respect to fiber-sum decompositions. We can conclude that such Lefschetz fibrations are prime and fundamental. In this paper, we determine the canonical classes of nonminimal Lefschetz fibrations admitting spheres of square - 1 whose total intersection number with generic fiber is big. As a consequence, we consider the Kodaira dimension and the geography problem of such Lefschetz fibrations.

The purpose of this research is to clarify the requirements for the length of the SMA belt for a SMA engine. In order to put the SMA engine in practical use, maximizing the output power density is most important from the viewpoint of economic efficiency. In the former paper we showed that the output power of the SMA engine highly depends on the diameter of the SMA belt , the radius of the high-temperature wheel and the radius of the low-temperature wheel. In this study we will change the diameter of the SMA belt and theoretically explain whether there is a relational expression between the diameter and the length. If the length of the SMA belt is determined, the height of the SMA engine is also determined. Since the output of the SMA engine can be calculated by the already derived theoretical formula, we can divide it by the volume of the SMA engine and thus, calculate the output power density of the SMA engine. As the result, changing the diameter of the SMA belt, we can calculate the most appropriate value, at which the output power density of the SMA engine is maximal.