MR-cholangiopancreatography using three-dimensional Fourier transfer fast asymmetric spin-echo method (3DFT-FASE)--clinical evaluation

MR-cholangiopancreatography (MRCP) is a new and non-invasive method. With the three-dimensional Fourier transform fast asymmetric spin-echo (3DFT-FASE) method that allows data collection as volume and three-dimensional expression, a higher spatial resolution can be obtained in the direction of both slab thickness and in-plane. In this method, analysis by multi planar reconstruction (MPR) and observation from various angle by maximum intensity projection (MIP) are available. Although further studies are required to shorten the imaging time to stop breathing only once, to use the respiratory gating or navigator echo, clinically useful diagnosis are possible utilizing by the advantages of the 3DFT method.     

1.1-μm-Range High-Speed Tunnel Junction Vertical-Cavity Surface-Emitting Lasers

We have developed novel 1.1-mum-range buried type-II tunnel junction vertical-cavity surface-emitting lasers (VCSELs) with a dielectric mirror for high-speed optical interconnections. A relaxation oscillation frequency of 27 GHz was achieved. The maximum 3-dB bandwidth was over 24 GHz. Error-free 30-Gb/s operation using a 2⁷ -1-length pseudorandom bit sequence was demonstrated using directly modulated multimode VCSELs.     

Active vibration control of a motor system by using H∞ control theory

This paper considers the vibration control of a motor system which has a motor and a load connected with a flexible shaft. However, this system often generates a shaft torsional vibration. Traditional methods of treating this problem to adjust the PID controller so that the closed-loop frequency response is slower than that of the vibration mode. On the other hand, one method has already been proposed in which the vibration is suppressed by a disturbance observer. This paper proposes a new approach based on H_∞ control theory. For comparison, a PI control system based on classical control theory also is constructed. The results of several experiments show that compared with the PI control system, the H_∞ control system is effective in suppressing the vibration. Further, the H_∞ controller obtained in the study consists of a PI controller and a series compensator that functions as an active vibration controller.     

Studies on the role of platelet-activating factor in blood pressure regulation

Circulating levels of 1-O-hexadecyl-2-acetyl-sn-glycero-3-phosphocholine (C₁₆PAF) in human subjects were measured by gas chromatography/mass spectrometry using negative ion chemical ionization. The mean (±S.D.) circulating C₁₆PAF levels in patients with essential hypertension (18.1±5.3 pg/mL, n=16) were not significantly different from those in normotensive subjects (17.2±7.2 pg/mL, n=14). During a salt balance study, high salt intake (20 g/day) significantly increased the circulating level of C₁₆PAF, and changes in circulating C₁₆PAF significantly and positively correlated with changes in mean arterial blood pressure (r=0.47, p<0.05). Changes in C₁₆PAF also correlated with changes in creatinine clearance (r=0.55, p<0.05), but did not correlate with changes in plasma sodium concentration, plasma chloride concentration and plasma volume. An intravenous injection of 50 μg of human atrial natriuretic peptide (hANP) decreased circulating C₁₆PAF levels from 20.0±2.7 to 13.9±2.4 pg/mL of blood (n=10, p<0.01) in healthy subjects. The data appear to indicate that C₁₆PAF levels are changed by salt intake-induced mild increase in blood pressure, and that hANP may be an endogenous factor which lowers circulating C₁₆PAF. Based on a paper presented at the Third International Conference on Platelet-Activating Factor and Structurally Related Alkyl Ether Lipids, Tokyo, Japan, May 1989.     

Thermal stability of the interface between discharged non-graphitizable carbon and electrolyte for lithium-ion batteries

The thermal stability of a non-graphitizable carbon electrode was studied quantitatively by differential scanning calorimetry (DSC). Charged non-graphitizable carbon electrode powder gave exothermic peaks at around 300 °C and the heat values varied depending on the ratio of the electrode powder to coexisting electrolyte solution. Based on the similarities in the exothermic behaviors of charged graphite and non-graphitizable carbon electrodes, the exothermic reactions at around 300 °C should be assigned to the reductive decomposition of a surface film by charged non-graphitizable carbon. On the other hand, non-graphitizable carbon electrode powder showed exothermic reactions at around 290 °C even at a discharged state, while almost no exothermic heat was seen for a discharged graphite electrode powder at temperatures above 250 °C. The heat values decreased as Li-ions in the non-graphitizable carbon electrode were extracted. Based on the present results and a consideration of the slow diffusion and irreversible trapping of Li-ions in non-graphitizable carbon, Li-ions remaining in non-graphitizable carbon could induce exothermic reactions at around 290 °C, even at a discharged state.     

Decomposition characteristics of Al-Mn-Zr alloys rapidly-quenched from the melt

The rapidly-quenched structures of liquid Al-Mn-Zr ternary alloys and Al-Mn binary alloys and their decomposition behaviors were investigated by hardness tests, X-ray diffraction analyses, and TEM observations. The solid solubility of Mn can be extended to about 10 wt pct irrespective of whether the alloys contain 1 wt pct Zr or not. The solidification structures are composed of fine dendritic cells and with increasing Mn content, interdendritic precipitates gather volume and branch out into the cell grains. The decomposition of rapidly-quenched alloys takes place during aging for 1 hour at temperatures of 300 to 350 °C, and the dependence of the decomposition temperatures on the Mn content varies in this range. Precipitation hardening of the ternary alloys is intensified by the addition of Mn up to about 7 wt pct and proceeds in a two-step manner during aging in the temperature range examined (350 to 450 °C). It is suggested that the precipitates contributing to the maximum hardening are pseudomorphous to the Al₆Mn equilibrium phase.     

Comparison of magnetoencephalography, functional MRI, and motor evoked potentials in the localization of the sensory-motor cortex

To clarify the topographical relationship between peri-Rolandic lesions and the central sulcus, we carried out presurgical functional mapping by using magnetoencephalography (MEG), functional magnetic resonance imaging (f-MRI), and motor evoked potentials (MEPs) on 5 patients. The sensory cortex was identified by somatosensory evoked magnetic fields using MEG (magnetic source imaging (MSI)). The motor area of the hand region was identified using f-MRI, during a hand squeezing task. In addition, transcranial magnetic stimulation localized the hand motor area on the scalp, which was mapped onto the MRI. In all cases, the sensory cortex was easily identified by MSI and the results of MSI correlated well with the findings obtained by the intraoperative recording of somatosensory evoked potentials. In contrast, the motor cortex could not be localized by f-MRI due to either the activated signal of the large cortical vein or the lack of any functional activation in the area of peri-lesional edema. MEPs were also unable to localize the entire motor strip. Therefore, at present, MSI is considered to be the most reliable method to localize peri-Rolandic lesions [corrected].     

The manipulator language with the characteristic of a functional programming language

This article describes the motion-oriented robot language IML (interactive manipulator language) with the characteristic of a functional programming language. The main functions of IML are (1) It is possible to describe the iterative motions without using a loop. (2) The user-defined procedures (commands) can be called by specifying the command name. (3) It is possible to describe robot motion (a sequence of the position and orientation of a robot hand) and force magnitude in the task-oriented Cartesian coordinate system (task coordinate system) suitable for robot tasks. Furthermore, it is possible to describe the translation and rotation of the coordinate system without syntactic distinction. (4) As the teaching data can be easily embedded in the language and can be played back in the force control mode, complex task programming becomes easy. In IML, as the user-defined command and the teaching data can be used just as the builtin system command; the system can be extended easily and naturally. In this article these features are described, and it is shown that these functions can be realized with the unified representation by introducing the concept of a functional programming language. The effectiveness of IML was confirmed by actually making a robot perform some tasks programmed in IML.     

Effect of carbonaceous materials on electrochemical properties of nano-sized Fe2O3-loaded carbon as a lithium battery negative electrode

Nano-sized Fe₂O₃-loaded carbon material was prepared by loading Fe₂O₃ on carbon using various carbonaceous materials. Carbonaceous materials strongly affected the electrochemical behavior of nano-sized Fe₂O₃-loaded carbon. Among the carbons used, nano-carbons such as acetylene black (AB), tubular carbon nanofibers (CNF), and platelet CNF provided larger capacities than other carbons. This may be due to the greater surface area of nano-carbon, which gives a greater distribution of nano-sized Fe₂O₃ particles than other carbons and delivers a greater capacity than other carbons. Investigation of the first-cycle materials by X-ray photoelectron spectroscopy (XPS) revealed that Fe₂O₃ was reduced to Fe metal in the charge process (reduction of Fe₂O₃), and, conversely, Fe metal was not completely oxidized to Fe₂O₃ during discharge (oxidation of Fe). This result may be due to the covering of non-conductive Li₂O formed during charging.