Experimental rat model representing both acute and chronic heart failure related to autoimmune myocarditis

The most important clinical manifestation of myocarditis is congestive heart failure. The precise mechanisms of heart failure during myocarditis have not been elucidated because no animal model that would permit in vivo study of hemodynamics in severe active myocarditis has been available. We monitored hemodynamics and left ventricular function in a rat model of experimental autoimmune myocarditis to determine if this model could be useful for the study of in vivo hemodynamics in severe active myocarditis. Lewis rats were immunized with human cardiac myosin suspended in complete Freund's adjuvant. Baseline hemodynamics were measured using an ultraminiature catheter pressure transducer via the right internal carotid artery, 4 weeks after immunization in one group of rats (acute phase) and 3 months after immunization in another group (chronic phase). Untreated rats served as the control group. Hemodynamic measurements were also obtained after infusion of dobutamine in the acute-phase and chronic-phase groups. The heart weight-to-body weight ratios were significantly higher in both the acute-phase group and the chronic-phase group compared with normal control rats. The baseline left ventricular systolic pressure was significantly lower in the chronic phase group than in the control group. Peak dP/dt and peak -dP/dt were significantly lower in both the acute-phase group and the chronic-phase group compared with the control group. Dobutamine significantly increased left ventricular systolic pressure, peak dP/dt, and peak -dP/dt in the chronic-phase group but caused only minor changes in hemodynamic variables in the acute-phase group. In vivo measurements of hemodynamic variables indicated the presence of left ventricular dysfunction in rats with experimental autoimmune myocarditis. This animal model may be useful for the study of both acute heart failure related to acute myocarditis and chronic heart failure due to diffuse myocardial fibrosis.     

HIMADES-1: a hierarchical machine design system based on the structure model for a machine

A structure model is presented which can represent not only the simplified geometry of an individual part but also the whole structure of a machine. The model is derived from observation of the general features of a machine, ie the hierarchy and the topology (connectivity) among parts. The model plays an important role in developing a CAD system to aid designers in the primary design stage, because a general method for representing the whole structure of a machine is needed at that stage. An interactive machine design system named HIMADES-1 has been developed. The data structure of the system is based on the above structure model. The system has some original features, the most distinctive of which is the unified algorithm for dimension matching and motion analysis which reduces design labour in the primary stages of machine design.     

Anodic oxidation of diphenyldiselenide in acetonitrile

The electrochemical behaviour of diphenyldiselenide in acetonitrile solution was studied by several electrochemical techniques. Controlled potential electrolysis in the presence of cyclohexene was also studied. The cyclic sweep voltammogram exhibited two irreversible anodic peaks at 1.35 and 1.65 V and one cathodic peak at ?1.25 V. It was concluded that the primary step is one-electron removal from the substrate, and the SeSe bond cleavage follows to generate phenylselenium cation and phenylselenium radical, of which the former species can react with cyclohexene to give mainly 2-acetamido-1-phenylseleno-cyclohexane. The possibility of utilizing phenylselenenic acid as the current mediator in the allylic hydroxylation reaction seems very limited. The cathodic reaction of diphenyldiselenide was also discussed briefly.     

Coordinated transportation of a single object by two nonholonomic mobile robots

We propose a decentralized control algorithm for transporting a single object by two nonholonomic mobile robots. One of the robots acts as a leader, whose trajectory is planned by itself or defined previously, whereas the other robot, referred to as a follower, follows the leader by keeping a constant distance from the leader. The follower can also avoid obstacles while following the leader without any absolute information about their position. Furthermore, the two mobile robots can realize an omnidirectional motion of the object when the leader broadcasts some simple information to the follower. Some simulation results show a good performance by the proposed decentralized control algorithm. This work was presented, in part, at the Seventh International Symposium on Artificial Life and Robotics, Oita, Japan, January 16–18, 2002.     

Understanding user commands by evaluating fuzzy linguistic information based on visual attention

This article proposes a method for understanding user commands based on visual attention. Normally, fuzzy linguistic terms such as “very little” are commonly included in voice commands. Therefore, a robot’s capacity to understand such information is vital for effective human-robot interaction. However, the quantitative meaning of such information strongly depends on the spatial arrangement of the surrounding environment. Therefore, a visual attention system (VAS) is introduced to evaluate fuzzy linguistic information based on the environmental conditions. It is assumed that the corresponding distance value for a particular fuzzy linguistic command depends on the spatial arrangement of the surrounding objects. Therefore, a fuzzy-logic-based voice command evaluation system (VCES) is proposed to assess the uncertain information in user commands based on the average distance to the surrounding objects. A situation of object manipulation to rearrange the user’s working space is simulated to illustrate the system. This is demonstrated with a PA-10 robot manipulator.     

Central pattern generators based on Matsuoka oscillators for the locomotion of biped robots

Biologically inspired control approaches based on central pattern generators (CPGs) with neural oscillators have been drawing much attention for the purpose of generating rhythmic motion for biped robots with human-like locomotion. This article describes the design of a neural-oscillator-based gait-rhythm generator using a network of Matsuoka oscillators to generate a walking pattern for biped robots. This includes the proper consideration of the oscillator’s parameters, such as a time constant for the adaptation rate, coupling factors for mutual inhibitory connections, etc., to obtain a stable and desirable response from the network. The article examines the characteristics of a CPG network with six oscillators, and the effect of assigning symmetrical and asymmetrical coupling coefficients among oscillators within the network structure under different possible inhibitions and excitations. The kinematics and dynamics of a five-link biped robot have been modeled, and its joints are actuated through simulation by the torques output from the neural rhythm generator to generate the trajectories for hip, knee, and ankle joints. The parameters of the neural oscillators are tuned to achieve flexible trajectories. The CPG-based control strategy is implemented and tested through a simulation. This work was presented in part at the 12th International Symposium on Artificial Life and Robotics, Oita, Japan, January 25–27, 2007     

A fuzzy logic based approach to the SLAM problem using pseudolinear models with multiframe data association

This paper presents an alternative solution to simultaneous localization and mapping (SLAM) problem by applying a fuzzy Kalman filter using pseudolinear process and measurement models. Nonlinear process model and observation model are formulated as pseudo-linear models and rewritten with a composite model whose local models are linear according to Takagi-Sugeno (T-S) fuzzy model. Using the Kalman filter theory, each local T-S model is filtered to find the local estimates. The linear combination of these local estimates gives the global estimate for the complete system. Data association to correspond features to the observed measurement is proposed with two sensor frames obtained from two sensors. The above system is implemented and simulated with Matlab to claim that the proposed method yet finds a better solution to the SLAM problem, though nonlinearity is directly involved in the Kalman filter equations, compared to the conventional approach. This work was presented in part at the 13th International Symposium on Artificial Life and Robotics, Oita, Japan, January 31–February 2, 2008     

Deformation behaviour of recrystallized Ni3Al

Deformation behaviour of the recrystallized Ni₃AI with non-stoichiometric and stoichiometric compositions have been investigated. Recrystallization microstructures in non-stoichiometric Ni₃AI are composed of the Ll₂ ordered and a small amount of the f c c disordered . It is shown that the large elongation of non-stoichiometric Ni₃AI is due to -phase existing at recrystallized t'- grain boundaries. Recrystallization microstructures in stoichiometric Ni₃AI are confirmed to be a single phase of . Coarse-grained stoichiometric Ni₃AI shows considerable ductility, although the fine-grained compound is brittle. The ductility may be related to the low yield strength in the coarse-grained samples.     

Plastic deformation mode of retainedβ phase inβ-eutectoid Ti-Fe alloys

Plastic deformation mode of-eutectoid Ti-Fe alloys has been investigated at 300 and 77 K in a retained single phase (containing athermal phase). Surface analysis and transmission electron microscopy show that {332}1 1 3 twinning and 1 1 1 slip appear to be dependent on orientation, composition and deformation temperature. The {3 3 2} 1 1 3 twinning appears only in metastable regions adjacent to the M_s curve in good agreement with previous work in-isomorphous alloys. Orientation dependence for occurrence of the preferential {332} 1 1 3 twinning among the twelve equivalent twinning systems can be explained in terms of the Schmid factor and the polarization of twinning shear. It is concluded that the {332} <1 1 3 twinning is common for-titanium alloys and related to the instability of the phase.