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Venus is among the most enigmatic and interesting places to explore in the solar system. However, the surface of Venus is a very hostile, rocky environment with extreme temperatures, pressures, and chemical corrosivity. A planetary rover to explore the surface would be scientifically valuable, but must use unconventional methods in place of traditional robotic control and mobility. This study proposes that a tensegrity structure can provide adaptivity and control in place of a traditional mechanism and electronic controls for mobility on the surface of Venus and in other extreme environments. Tensegrity structures are light and compliant, being constructed from simple repeating rigid and flexible members and stabilized only by tension, drawing inspiration from biology and geometry, and are suitable for folding, deployment, and adaptability to terrain. They can also utilize properties of smart materials and geometry to achieve prescribed movements. Based on the needs of scientific exploration, a simple tensegrity rover can provide mobility and robustness to terrain and environmental conditions, and can be powered by environmental sources such as wind. A wide variety of tensegrity structures are possible, and some initial concepts suitable for volatile and complex environments are proposed here.

Atherosclerosis is a chronic inflammatory disease inflicting the arterial wall, and endothelial activation and dysfunction play an important role in its pathogenesis. The RNA-binding protein HuR has been associated with events of inflammation and activation in endothelial cells, however, its connection with atherosclerosis remains unclear. Here, we show that the expression and RNA-binding activity of HuR are upregulated in human and mouse atherosclerotic lesions. In addition, proatherogenic stimuli, such as inflammatory lipids (Ox-PAPC) and cytokines (TNF-α and IL-1β), induce HuR in human aortic endothelial cells (HAECs) in vitro. Moreover, HuR is also induced in mouse aorta ECs fed a high-fat diet, and the inducible degree is correlated with proatherogenic hyperlipidemia. We further show that the MAPK/ErK pathway in ECs is activated by proatherogenic stimuli in vitro and by high-fat diet in vivo. Finally, we demonstrate that the MAPK/ErK pathway is required for HuR induction by proatherogenic stimuli. Altogether, our study uncovers the inducible effect of proatherogenic stimuli on HuR in ECs, and connects this effect to the activated MAPK/ErK pathway.

Venus is a planet that we would very much like to further explore and understand. However, the surface of Venus is very hostile environment with a surface temperature averaging 452 degrees centigrade at an atmospheric pressure of 93 bar, with the atmosphere composed mainly of carbon dioxide with clouds of sulfuric acid. Missions to the surface of Venus have succeeded, but mission lifetime is extremely short, on the order of minutes to hours, until materials melt and electronic components fail due to the extreme conditions. A small rover that would be capable of exploring the surface would be scientifically valuable, but requires unconventional thinking to be able to survive the environment. We present a study of means by which to design a small planetary rover that uses a bio-inspired flexible tensegrity structure and operates mechanically to utilize the conditions of the Venusian surface in its operation. Tensegrity robots make use of geometrically-inspired and bio-inspired structures that allow multiple degree of freedom movement. These structures are sparse, composed of linked tension and compression members in a similar manner to a truss, and are very lightweight compared to traditional mobile robots and retainin the ability to flexibly adapt to terrain and fold for transport. The use of a tensegrity structure also has benefits in terms of simplicity of structure, in the sense that structural elements are simple and repeatable, held in place only by the tension of materials. This allows tensegrity rovers to utilize smart materials and structural properties in operation, without the use of complex joints and bearings to allow full-body movements. The use of flexible structures allows the rover to transform and re-configure itself to a limited extent in the field in response to environmental factors. In this paper, a concept and feasibility study of a small tensegrity rover that utilizes mechanical operation will be examined for Venus exploration, with consideration of previous missions and their lessons. The use of the rover for scientific exploration will also be justified. The results of this study will also benefit terrestrial applications that require robotic operation in the presence of extremes of temperature and pressure. The work will be used for the development of space technology for very harsh and hot planetary exploration.

Autonomous Robotic vehicles represent a key and fast-moving technology area in space exploration and exploitation. We aim to to make future operations on other planets more affordable, reliable, and responsive by developing better and more useful mobile robots that can be deployed on other planets, and expediting this process by applying similar technologies to robotic applications on Earth. These robots must be responsive, energy efficient, lightweight for transport, and mechanically robust. To accomplish these goals, we have developed the Aria micro-rover platform based on micro-rover concepts for low-cost Mars surface and subsurface exploration and inspired by the recent resurgence of interest in planetary exploration. The Aria is designed using a novel methodology for probabilistic autonomy programming that makes use of Bayesian networks for highly reliable sensor fusion, planning, and behaviour control. Autonomy and AI are accomplished by inference-based reasoning into stored probabilistic data, and includes probabiliistic learning and self-programming. A fully distributed electronic component architecture with fault tolerance increases modularity and adaptability. Reliability is maximized and cost of deployment is minimized by modularly re-using common hardware and components. Also, the mechanical structure uses a lightweight and flexible actuated space frame to increase resiliency and allow full-body movements. The use of flexible structures allows the rover to transform and re-configure itself to a limited extent in the field. The physical design is driven by the need for light weight, simplicity and reconfigurability, with a minimalist mechanical structure and a flexible software design model to facilitate additions and multiple use cases. To lower cost of construction and transport, mass is minimized through the use of thin structural members and wire members in tension to create resilience without adding additional material. The Aria platform is unique in its aim to be constructed using as much automation as possible during manufacture. The chassis makes use of a jointed frame that can be assembled using additive manufacturing methods. The electronics are common modules that are attached and connected during the manufacturing process using a common bus architecture and later programmed for component-specific duties. The mission responsiveness of the platform is very high due to the ability to re-use and re-configure modules as needed for mission changes. This also opens the possibility for rovers to be mass-produced and deployed autonomously, or even assembled on another planet by using local materials to save transport of mass. In addition to the ability to be deployed as a planetary rover for scientific or resource management use, the Aria rover is targeted at terrestrial applications by using similar but non space qualified electronics to lower cost and increase availability. The primary applications targeted are 1) agricultural field monitoring and intervention, 2) environmental sensing and research uses, and 3) surveillance and disaster response. The Aria rover platform represents a new paradigm in deploying mobile robots to perform remote missions on Earth and other planets. Prototypes are currently being tested, and the technologies refined to produce more reliable, responsive, and flexible configurations for the applications of the future.

Objective To determine whether long-term survival (>10 years) after heart transplantation is possible and identify complications influencing long-term survival. Methods We analyzed clinical outcomes in the group of 21 patients who had undergone heart transplantation at the Second Affiliated Hospital of Harbin Medical University since 1992 and 4 of them survived more than 10 years. Results Nine patients are still alive with normal left ventricular function, and 4 of them have survived more than 10 years. The longest survival patient has lived more than 18 years after transplantation, whose survival is the longest in China and in Asia. We have also found that there has been a high incidence of complications, such as rejection episodes during the first 6 months, and transplant vasculopathy in the long-term survival patients. Conclusion Long-term survivors maintain normal hemodynamic function of their allografts, and long-term survival following cardiac transplantation is possible. Aggressive preventive and therapeutic measures are essential to limit the risk factors for development of complications such as rejection episodes and transplant vasculopathy, and enable long-term survival after cardiac transplantation.

大阪大學中國文化論壇 討論文件, 概要:中国語, 訳:滝本, 理博

This paper presents a deep space formation flying mission using microsatellites with pulsed plasma thrusters and solar sails as propulsion systems. The circular restricted three body problem with consideration of solar gravitation was used as the equation of motion. Formation flying near Earth Moon triangular libration points uses short period trajectories as relative references. Simulation results using a nonaffine control strategy are provided to demonstrate the effectiveness of the proposed propulsion systems for formation flying near triangular libration points.

In this work, a tracker spacecraft equipped with a short-range vision system is tasked with visually identifying a target spacecraft and determining its relative angular velocity and relative linear velocity using only visual information from onboard cameras. Focusing on methods that are feasible for implementation on relatively simple spacecraft hardware, we locate and track objects in three-dimensional space using conventional high-resolution cameras, saving cost and power compared to laser or infrared ranging systems. Identification of the target is done by means of visual feature detection and tracking across rapid, successive frames, taking the perspective matrix of the camera system into account, and building feature maps in three dimensions over time. Features detected in two-dimensional images are matched and triangulated to provide three-dimensional feature maps using structure-from-motion techniques. This methodology allows one, two, or more cameras with known baselines to be used for triangulation, with more images resulting in higher accuracy. Triangulated points are organized by means of orientation histogram descriptors and used to identify and track parts of the target spacecraft over time. This allows some estimation of the target spacecraft's motion even if parts of the spacecraft are obscured or in shadow. The state variables with respect to the camera system are extracted as a relative rotation quaternion and relative translation vector for the target. Robust tracking of the state variables for the target spacecraft is accomplished by an embedded adaptive unscented Kalman filter. In addition to estimation of the target quaternion from visual Information, the adaptive filter can also identify when tracking errors have occurred by measurement of the residual. Significant variations in lighting can be tolerated as long as the movement of the satellite is consistent with the system model, and illumination changes slowly enough for state variables to be estimated periodically. Inertial measurements over short periods of time can then be used to determine the movement of both the tracker and target spacecraft. In addition, with a sufficient number of features tracked, the center of mass of the target can be located. This method is tested using laboratory images of spacecraft movement with a simulated spacecraft movement model. Varying conditions are applied to demonstrate the effectiveness and limitations of the system for online estimation of the movement of a target spacecraft at close range.

The successful miniaturization of spacecraft subsystems makes nanosatellites suitable candidates for many scientific missions, and several miniaturized electric propulsion systems on CubeSats have been studied. A Cubesat employing a Pulsed Plasma Thruster module is currently under development by Clyde Space Ltd, Mars Space Ltd and the University of Southampton under contract to ESA and is now entering final qualification testing. Pulsed Plasma Thrusters have been used in satellite attitude control studies of nadir pointing, and satellite rendezvous, docking and formation flying. This paper considers the use of the PPTCUP Pulsed Plasma Thruster in a range of different operational cases that are considered key to the success of many future nanosatellite missions, including moderate low thrust orbit inclination and altitude changes, deorbiting a satellite at the end of life, maintaining "a string of pearls" constellation, on-orbit servicing and inspection of a mother satellite, and life extension of an ISS-deployed nanosatellite. PPTCUP uses a very fast electric discharge to ablate a tiny amount of a solid propellant bar, which is then ionized and expelled at high velocity to generate thrust. To generate such a discharge, the thruster charges a high performance capacitor bank for up to a second before discharging it in few microseconds. Based on a current generation system with a mean power input of 2 W, a 40 uN thrust pulse (with a 20 N peak force) can be achieved 1 million times in succession. In order to evaluate the PPTCUP thruster performance, a simulation model has been developed and applied to the identified scenarios, leading to suggestions for baseline control laws suited for the mission. Where necessary, refinement of the design point has been performed to provide a roadmap for future PPTCUP development. We assume a nanosatellite that has a maximum mass of 4 kg at 320-380 km. Drag force and yearly velocity increments are estimated as functions of altitude, drag cross-section and solar activity. Assuming an analysis of a 3U Cubesat frame with PPTCUP, a control approach based on advanced control methods will be used to handle different operational cases. This work finds immediate application for the PPTCUP for challenges such as drag compensation, de-orbiting, and rendezvous and docking manoeuvres, and makes recommendations for future targeting of performance to further improve the capability of PPTCUP equipped satellites. In particular it is noted that advanced control design would improve the coverage of this class of thruster.

A novel adaptive unscented Kalman filter (AUKF) based estimation algorithm is proposed for a 3U Cubsat. This small satellite employs a three axis magnetometer and three MEMS gyroscopes as well as three magnetic torque rods and one reaction wheel on the pitch axis. Unlike the existing UKF, in this paper, an n+1 sigma set is used to estimate the nanosatellite attitude instead of 2n + 1 sigma points as in a conventional UKF. Numerical Simulation results validate the performance of the proposed adaptive Kalman filter. There is no need for linearization of the nonlinear dynamics of the system. The estimated result tracks satellite attitude during the damping and stable control stages. Euler angles, gyro bias, and angular velocity of the satellite are estimated using this proposed AUKF with good convergence time and estimation accuracy.