Production of docosahexaenoic acid by marine bacteria isolated from deep sea fish

Five bacterial strains isolated from the intestine of deep sea fish were shown to produce docosahexaenoic acid (22∶6n−3; DHA) at a level of 6.4 to 11.6% of total fatty acids when incubated in DHA-free medium. In all of the strains examined, other polyunsaturated fatty acids were barely detectable, except for eicosapentaenoic acid (20∶5n−3). A typical strain, such as T3615, produced DHA at a concentration of about 0.8 mg/L within six days of aerobic incubation at 5°C and under atmospheric pressure. The T3615 strain, belonging to the genusVibrio, is rod-shaped, Gram-negative, motile and facultatively anaerobic.     

Essence of generalized partial computation

Generalized partial computation (GPC) is a program optimization principle based on partial computation and theorem proving. Conventional partial computation methods (or partial evaluators) explicitly make use of only given parameter values to partially evaluate programs. However, GPC explicitly utilizes not only given values but also the following information: (1) logical structure of a program to be partially evaluated; (2) abstract data type of a programming language. The main purpose of this paper is to present comprehensible examples of GPC. Graphical notations, called GPC trees, are introduced to visibly describe GPC processes.     

Angina pectoris caused by coronary microvascular spasm

BACKGROUND: Microvascular angina can occur during exercise and at rest. Reduced vasodilator capacity of the coronary microvessels is implicated as a cause of angina during exercise, but the mechanism of angina at rest is not known. Our aim was to test the hypothesis that primary hyperconstriction (spasm) of coronary microvessels causes myocardial ischaemia at rest. METHODS: Acetylcholine induces coronary artery spasm in patients with variant angina. We tested the effects of intracoronary acetylcholine at graded doses in 117 consecutive patients with chest pain (at rest, during exertion, or both) and no flow-limiting (>50%) organic stenosis in the large epicardial coronary arteries. We also assessed the metabolism of myocardial lactate during acetylcholine administration in 36 of the patients by measurement of lactate in paired blood samples from the coronary artery and coronary sinus vein. FINDINGS: Of the 117 patients, 63 (54%) had large-artery spasm, 29 (25%) had microvascular spasm, and 25 (21%) had atypical chest pain. The 29 patients with microvascular spasm developed angina-like chest pain, ischaemic electrocardiogram (ECG) changes, or both spontaneously (two patients) or after administration of acetylcholine (27 patients) without spasm of the large epicardial coronary arteries. Testing of paired samples of arterial and coronary sinus venous blood showed that lactate was produced during angina attack in nine of 11 patients with microvascular spasm. There was more women (p<0.01) and fewer coronary risk factors (p<0.01) in patients with microvascular spasm than in those with large-artery spasm. INTERPRETATION: Coronary microvascular spasm and resultant myocardial ischaemia may be the cause of chest pain in a subgroup of patients with microvascular angina.     

Synchronous generator control using neural network-based nonlinear adaptive regulator

Control equipment of synchronous generators such as automatic voltage regulators, speed governors and power system stabilizers have been developed to maintain stability and to improve damping of power systems. When an operating condition changes greatly, however, such controllers may become less effective because of nonlinearity of the power system. In this paper, a nonlinear adaptive generator control system using neural networks is proposed. The proposed neurocontrol system consists of two neural networks which work as an identifier and a controller, respectively, and generates supplementary control signals to the conventional controllers. An essential feature of the proposed system is that the internal connection weights of both neural networks are adjusted adaptively so as to generate appropriate control signals for transient stability and damping enhancement in response to changes of the operating conditions and the network configuration. To investigate the control performance of the proposed neurocontrol system, digital time simulations are carried out for a one-machine infinite bus model system. As a result, it is clarified that the proposed adaptive neurocontrol system effectively improves the system damping and shows adaptability against the wide changes of the operating conditions.     

Inelastic behaviour of steel under plasticity-creep interaction condition: An interim report of the Bench Mark project by the subcommittee on inelastic analysis and life prediction of high temperature materials, JSMS

Some of the interim results of the Bench Mark Project by the Subcommittee on the Inelastic Analysis and Life Prediction of High Temperature Materials, JSMS, is presented. The purpose of the present bench mark study is to review and evaluate the inelastic constitutive models relevant to material response under the plasticity-creep interaction.By specifying normalized and tempered steel at 600°C, sixteen bench mark problems of four categories are first established: (I) tensile stress-strain relations and creep curves, (II) material response under mixed modes of plastic and creep loading, (III) ratcheting and deformation under program loads, and (IV) cyclic deformation behaviour under the combination of different strain rates. Then, the outline of seventeen inelastic constitutive models of nine types discussed in this project is presented. Finally, the interim results of these bench mark tests are compared with the corresponding predictions of the constitutive models to evaluate their accuracy in simulating the actual behaviour of the material.     

Significance of residual stress on fatigue properties of welded pipes

The mean stress effect on the fatigue properties of two kinds of welded pipes was investigated in cantilever bending. The fatigue strength changed with the mean stress on fillet welded pipes, but did not change on butt welded pipes. The fatigue crack initiated from the toe of weld on the outer surface of fillet welded pipes and from the undercut on the inner surface of butt welded pipes. The measurement of the fatigue crack propagation rate and the residual stress distribution through the thickness of pipe revealed that the difference in the fatigue properties between fillet and butt welded pipes arose from the weld-induced residual stress, tension on the inner surface and compression on the outer surface. It is suggested that the production of compressive residual stress along the inner surface would be an effective means for improving the fatigue strength of butt welded pipes.     

High pressure differential thermal analysis (HPDTA) of fatty acid methyl esters and triglycerides

When using high pressure differential thermal analysis to study the stability of a fatty methyl ester or triglyceride in an atmosphere of air, a departure from the base line in the exothermic curve is observed. The point where an extension line from the base line intersects a tangent line to the departure curve was selected as the transition point in the exothermic curve. For each sample studied, temperature at this transition point showed good reproducibility. The influence of sample container and air pressure upon the temperature of the transition point in the exothermic curve (TTE) was examined. A linear correlation between the number of double bonds in the sample and TTE was observed.     

Power law of molecular weight dependence of lateral growth rate of isotactic polypropylene

Molecular weight (M) dependence of the lateral growth rate (V) of α form crystal of isotactic polypropylene (iPP) was studied. Reliable equilibrium melting temperature determined in our previous study was used for the analysis of supercooling dependence of V. A power law of M of V, , was obtained, where H is a small constant (H = 0.7). The small H, which is similar to that of the hexagonal phase of polyethylene (H = 0.7) in comparison with the value of H = 1.7 for the orthorhombic phase of polyethylene, confirmed our prediction of smaller H for “rod like” chain polymers because of easier chain sliding within the interface between the crystalline phase and the melt. Thus, the universality of the important role of topological nature in polymer crystallization was confirmed. Lateral surface free energy (σ) of the α form of iPP was obtained as σ ≅ 1.59 × 10⁻⁶ J/cm².     

Note: Unshielded bilateral magnetoencephalography system using two-dimensional gradiometers

Magnetoencephalography (MEG) noninvasively measures neuronal activity with high temporal resolution. The aim of this study was to develop a new type of MEG system that can measure bilateral MEG waveforms without a magnetically shielded room, which is an obstacle to reducing both the cost and size of an MEG system. An unshielded bilateral MEG system was developed using four two-dimensional (2D) gradiometers and two symmetric cryostats. The 2D gradiometer, which is based on a low-T(c) superconducting quantum interference device and wire-wound pickup coil detects a magnetic-field gradient in two orthogonal directions, or ?/?x(?(2)B(z)/?z(2)), and reduces environmental magnetic-field noise by more than 50 dB. The cryostats can be symmetrically positioned in three directions: vertical, horizontal, and rotational. This makes it possible to detect bilateral neuronal activity in the cerebral cortex simultaneously. Bilateral auditory-evoked fields (AEF) of 18 elderly subjects were measured in an unshielded hospital environment using the MEG system. As a result, both the ipsilateral and the contralateral AEF component N100m, which is the magnetic counterpart of electric N100 in electroencephalography and appears about 100 ms after the onset of an auditory stimulus, were successfully detected for all the subjects. Moreover, the ipsilateral P50m and the contralateral P50m were also detected for 12 (67%) and 16 (89%) subjects, respectively. Experimental results demonstrate that the unshielded bilateral MEG system can detect MEG waveforms, which are associated with brain dysfunction such as epilepsy, Alzheimer's disease, and Down syndrome.