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In this paper, we propose a method to realize traffic information sharing among cars using inter-vehicle communication. When traffic information on a target area is retained by ordinary cars near the area, the information may be lost when the density of cars becomes low. In our method, we use the message ferrying technique together with the neighboring broadcast to mitigate this problem. We use buses which travel through regular routes as ferries. We let buses maintain the traffic information statistics in each area received from its neighboring cars. We implemented the proposed system, and conducted performance evaluation using traffic simulator NETSTREAM. As a result, we have confirmed that the proposed method can achieve better performance than using only neighboring broadcast., MDM'06 : 7th International Conference on Mobile Data Management , May 9-12, 2006 , Nara, Japan

In this paper, we propose a simulator for facilitating reliable and inexpensive development of ubiquitous applications where each application software controls a lot of information appliances based on the state of external environment, user’s contexts and preferences. The proposed simulator realistically reproduces behavior of application software on virtual devices in a virtual 3D space. For this purpose, the simulator provides functions to facilitate deployment of virtual devices in a 3D space, simulates communication among the devices from MAC level to application level, and reproduces the change of physical quantities (e.g., temperature) caused by devices (e.g., air conditioners). Also, we keep software portability between virtual devices and real devices. As the most prominent function of the simulator, we provide a systematic and visual testing method for testing whether a given application software satisfies specified requirements., UbiComp 2006 : 8th International Conference on Ubiquitous Computing , Sep 17-21, 2006 , Orange County, CA, USA

Aiming at fast establishment of a wireless network around a multi-level building in a disaster area, we propose an efficient method to determine the locations of network nodes in the air. Nodes are attached to balloons outside a building and deployed in the air so that the network can be accessed from anywhere in the building. In this paper, we introduce an original radio propagation model for predicting path loss from an outdoor position to a position inside a building. In order to address the three-dimensional deployment problem, the proposed method optimizes an objective function for satisfying two goals: (1) guarantee the coverage: the target space needs to be covered by over a certain percentage by wireless network nodes, (2) minimize the number of network nodes. For solving this problem, we propose an algorithm based on a genetic algorithm. To evaluate the proposed method, we compared our method with three benchmark methods, and the results show that the proposed method requires fewer nodes than other methods., BWCCA2013 : 8th International Conference on Broadband and Wireless Computing, Communication and Applications , Oct 28-30, 2013 , Compiegne, France

For accident prevention at intersections, it is useful for drivers to grasp the position of vehicles in blind spots. This can be achieved without infrastructure if some vehicles passing near the intersection capture and share live video of the intersection through inter-vehicle communications. However, such video streaming requires a congestion control mechanism. In this paper, aiming to let a driver grasp the situation at an intersection, we propose a method to select vehicles that send a video in order to generate a live bird's-eye-view video of the intersection. In our method, each vehicle at an intersection exchanges information with others, such as the sub-areas of the intersection it captures, the quality of its video, and its position and speed. Based on the exchanged information, each vehicle autonomously judges whether it should send its video or not. Through simulation with a QualNet simulator, we confirm that our method achieves a good video arrival rate and video quality sufficient for practical use., IVCS 2010 : 2nd IEEE International Intelligent Vehicular Communications System Workshop , Jan 9-12, 2010 , Las Vegas , NV, USA

In this paper, we propose a method for cars to autonomously and cooperatively collect traffic jam statistics to estimate arrival time to destination for each car using inter-vehicle communication. In the method, the target geographical region is divided into areas, and each car measures time to pass through each area. Traffic information is collected by exchanging information between cars using inter-vehicle communication. In order to improve accuracy of estimation, we introduce several mechanisms to avoid same data to be repeatedly counted. Since wireless bandwidth usable for exchanging statistics information is limited, the proposed method includes a mechanism to categorize data, and send important data prior to other data. In order to evaluate effectiveness of the proposed method, we implemented the method on a traffic simulator NETSTREAM developed by Toyota Central R&D Labs, conducted some experiments and confirmed that the method achieves practical performance in sharing traffic jam information using inter-vehicle communication., V2VCOM2006 : Vehicle-to-Vehicle Communications , Jul 17-21, 2006 , San Jose, CA, USA

In this paper, we propose a method for detecting the positions of pedestrians by cooperation of multiple cars with directional antennas to support drivers for pedestrian safety. In the method, each pedestrian carries a device which periodically transmits a beacon with a unique ID, and each car passing near the pedestrian receives the beacon by a directional antenna and measures the distance and the angle of arrival. We assume the distribution of the measurement errors to be a normal distribution, and the system calculates the existence probabilities of each pedestrian at each point. By exchanging information of the probabilities between cars, the area with high existence probability is narrowed down. In this paper, we first describe the situations where detecting positions of pedestrians greatly contribute to pedestrian safety, and then we describe the probability model used in our method, the method for calculating existence probabilities from information from multiple cars, and the protocol for exchanging the probability information between cars. We evaluated our method on QualNet simulator, and confirmed that the positions can be detected accurately enough for practical uses., GLOBECOM2008 : IEEE Global Communications Conference , Nov 30-Dec 4, 2008 , New Orleans, LA, USA

In vehicular ad hoc networks (VANETs), delivering messages to a specific location is difficult due to the high mobility of vehicles. In this paper, we propose a method for efficient message delivery in VANETs utilizing the route information in car navigation systems. In the proposed method, each car periodically exchanges the information on its current position and scheduled route in the car navigation system with neighboring cars within radio range. By referring to the exchanged information, each car forwards messages to the neighboring car that will most closely approach the destination. Through simulations, we confirm that the proposed method achieves a better delivery rate with low bandwidth usage than a geocast-based method and epidemic routing., IVCS 2010 : 2nd IEEE International Intelligent Vehicular Communications System Workshop , Jan 9-12, 2010 , Las Vegas , NV, USA

P2P networks can achieve high scalability sincethey distribute service contents/resources to multiple nodesin the network. In a P2P network, it is necessary to searchthe resource location on the network when we use somecontents/resources. Space filling curve is known as techniqueto map information of the multi-dimensional space such asthe location information onto the one-dimensional space suchas ID. In this paper, we propose a novel space filling curvefor configuring structured P2P overlay network consideringdelay based on the geographic information of each node.By using the proposed space filling curve, we can convertgeographic information of nodes into their ID (label) of P2Pnetwork. Through the numerical evaluation, we confirmed thatthe proposed curve is more suitable for handling hierarchicalspreadnodes than the conventional curves.

P2P networks can achieve high scalability sincethey distribute service contents/resources to multiple nodesin the network. In a P2P network, it is necessary to searchthe resource location on the network when we use some contents/resources. Space filling curve is known as technique tomap information of a multi-dimensional space such as locationinformation onto a one-dimensional space such as ID.We have proposed a novel space filling curve for P2P overlaynetworks considering the proximity of nodes based on the geographicalinformation of the nodes and reducing the communicationdelay proportional to the geographical distance of thenodes. By using the proposed space filling curve, we can convertgeographic information of nodes into their ID (label) ofP2P network. In this paper, we evaluate the space filling curvefor P2P networks and apply it on a virtual network map. Onthe virtual network map, each node has the coordinated positioninformation which is proportional to the communicationdelay with its neighbor nodes. Through the numerical evaluation,we confirmed that the proposed curve is more suitablefor handling hierarchical-spread nodes than the conventionalcurves on the virtual network map.

Acute myocardial infarction is a leading cause of death among single organ diseases. Despite successful reperfusion therapy, ischaemia reperfusion injury (IRI) can induce oxidative stress (OS), cardiomyocyte apoptosis, autophagy and release of inflammatory cytokines, resulting in increased infarct size. In IRI, mitochondrial dysfunction is a key factor, which involves the production of reactive oxygen species, activation of inflammatory signalling cascades or innate immune responses, and apoptosis. Therefore, intercellular mitochondrial transfer could be considered as a promising treatment strategy for ischaemic heart disease. However, low transfer efficiency is a challenge in clinical settings. We previously reported uptake of isolated exogenous mitochondria into cultured cells through co-incubation, mediated by macropinocytosis. Here, we report the use of transactivator of transcription dextran complexes (TAT-dextran) to enhance cellular uptake of exogenous mitochondria and improve the protective effect of mitochondrial replenishment in neonatal rat cardiomyocytes (NRCMs) against OS. TAT-dextran-modified mitochondria (TAT-Mito) showed a significantly higher level of cellular uptake. Mitochondrial transfer into NRCMs resulted in anti-apoptotic capability and prevented the suppression of oxidative phosphorylation in mitochondria after OS. Furthermore, TAT-Mito significantly reduced the apoptotic rates of cardiomyocytes after OS, compared to simple mitochondrial transfer. These results indicate the potential of mitochondrial replenishment therapy in OS-induced myocardial IRI.

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