A Model of the Relationship Between Psychosocial Variables and Diurnal Cortisol Rhythm Under Chronic Stress by Using Structural Equations

By using structural equations, we investigated the effect of chronic stress on salivary cortisol rhythm and proposed a causal model of chronic stress by using psychosocial and physiological data. First, 111 healthy workers (48 males, 63 females) completed questionnaires on chronic stress and lifestyle habits. Then, they provided saliva samples and answered questionnaires that were prepared to assess their psychological states 5 times (on waking up and at 10:00, 11:40, 14:00, and 16:00) on workdays. Structural equation modeling (SEM) revealed that chronic stress and longer commuting time resulted in sleep irregularities and this disrupted the cortisol circadian rhythm. This suggests that chronic stress disrupts the cortisol circadian rhythm even in healthy individuals, and sleep regularity mediates the effect of chronic stress on the cortisol rhythm.

     

Specific changes in human brain following reperfusion after cardiac arrest

BACKGROUND AND PURPOSE: Very few reports are available on serial changes in human brain after cardiac arrest. The primary objective of this study is to investigate sequential neuroradiological changes in patients remaining in a persistent vegetative state following resuscitation after cardiac arrest. METHODS: We repeatedly studied eight vegetative patients resuscitated from unexpected out-of-hospital cardiac arrest using computed tomographic (CT) scanning and high-field magnetic resonance (MR) imaging at 1.5 T. RESULTS: In seven of the eight patients, CT scans obtained between days 2 and 6 features symmetrical low-density lesions in the bilateral caudate, lenticular, and/or thalamic nuclei. These ischemic lesions were persistently of low density on serial CT scans. In these seven patients, MR images demonstrated what were thought to be hemoglobin degradation products derived from minor hemorrhages localized in the bilateral basal ganglia, thalami, and/or substantia nigra. Diffuse brain edema in the acute stage and diffuse brain atrophy in the chronic stage were consistent neuroradiological findings. No abnormal enhanced lesions were demonstrated by CT scans. CONCLUSIONS: The most characteristic findings on high-field MR images were symmetrical lesions in the bilateral basal ganglia, thalami, and/or substantia nigra with specific changes suggestive of minor hemorrhages that were not evident on CT scans. We speculate that these minor hemorrhages result from diapedesis of red blood cells in these regions during the reperfusion period through the endothelium disrupted by ischemia-reperfusion insult.     

Air vent in water chamber and surface coating on liner slides concerning auxiliary cooling system for the high temperature engineering test reactor

Experimental study was made to confirm the validity of new designs of the auxiliary cooling system for the high temperature engineering test reactor (HTTR). First, it is necessary to vent residence air in outlet side of water chamber of the auxiliary heat exchanger for the HTTR. Accordingly, we have proposed to mount a proper bend duct in the outlet side of the water chamber. Air vent is done by difference between pressures at both ends of the bend duct caused by the forced water circulation using the water pumps. From flow tests, it was confirmed that it is capable of venting the air through the bend duct by circulating the water in maximum capacity of the water pumps. Second, it is essential to prevent seizure and excessive wear of the liner slides of the auxiliary concentric hot gas duct for the HTTR at a service temperature of 950°C. Therefore, we have put forward to coat titanium nitride (TiN) on the surface of the liner slides made of nickel-based superalloy Hastelloy XR using the thermochemical vapor deposition method. As a result of seizure and wear tests, it was confirmed that the TiN coating film of 3 μm on the surface of Hastelloy XR is sufficient.     

Extensions of polyacrylic acid ammonium salts in the adsorption layer to fluidize alumina slurries

An average shell volume occupied in the adsorption layer on alumina by a polyacrylic acid ammonium salts molecule (PAA) defined as the average area occupied by an adsorbed PAA on alumina multiplied by the average thickness of the water layer at the limit of thickening, has been calculated from the adsorbed amount of PAA and from the flow points of alumina in the presence of PAA of different molecular weights. A steric effect of the PAA dispersant on the dispersion of alumina resulted in a flow with no yield stress. This was due to the change of the extension of PAA in the adsorption shell from a sphere to an ellipsoid with a long axis which exceeded the effective distance that the van der Waals attraction force reaches at a molecular weight for the PAA of between 10 000–20 000.     

Determination of assimilable organic carbon (aoc) in ozonated water with acinetobacter calcoaceticus

The effect of ozone application in drinking water on the production of assimilable organic carbon (AOC) was evaluated. The typical procedure to determine AOC is suggested by van der Kooij, which is the method of bacterial growth measurement by colony‐forming units using the strain P17 and/or NOX. The bacterial indicator species used for this study is Acinetobacter calcoaceticus which was isolated and identified while ozonating Nakdong river water. This strain could never be isolated from the raw water, but this strain was the predominant isolate in the ozonated water. Within a short incubation time, this organism was found to replicate well on acetate and oxalate as the sole carbon sources. The yield coefficients of this organism for acetate and oxalate are the same order of magnitude as the value of P17 and NOX. With full‐scale experiments, A. calcoaceticus concentration was found to increase after ozonation, but did not decrease upon chlorination. In laboratory‐scale experiments with Yongsan river water, aldehyes were found to be produced in proportion to the ozone dose. The raw water contains low concentrations of aldehydes, but has a high AOC concentration. A correlation between aldehyde production and AOC production was observed in the tested water with ozonation.     

Infrared sensing properties of positive temperature coefficient thermistors with large temperature coefficients of resistivity

Infrared (IR) detecting elements were prepared using positive temperature coefficient (PTC) thermistors with large temperature coefficients of resistivity (α). Their compositions were denoted as Ba_1−x Sr _x Nb_0.003Ti_0.997O₃ + 1 mol % TiO₂ + 0.07 mol %MnO (x=0, 0.2), and their temperature coefficients of resistivity were 78 and 50% K⁻¹, respectively. Their IR sensing properties were measured under the self-regulating heating conditions, and were compared with those of a detector with small α (18 % K⁻¹). It was shown that large α was effective for controlling the element temperature by self-regulating heating and for improving sensitivity. The responsivity,R _v of the element withx=0.2 was 980 VW⁻¹, and was as large as those of pyroelectric detectors. Expressions which normalize the sensitivity and the thermal time constant were derived. From these expressions, criteria for improving some IR sensing properties were obtained.     

Osteoclastic features of multinucleated giant cells responding to synthetic hydroxyapatite implanted in rat jaw bone.

Multinucleated giant cells (MGCs) that responded to synthetic hydroxyapatite (HAP) implanted in rat mandibles were studied with electron microscopy. HAP used in this study sintered at 200 degrees C (HAP200) and at 125 degrees C (HAP1250) after the synthesis by a wet method. One to three weeks after the intraosseous implantation of HAP, MGCs responding to HAP200 had not only well-developed ruffled border and the clear zone but well-developed perinuclear Golgi complex, many mitochondria and vesicles in their cytoplasms. MGCs responding to HAP1250 had the clear zone, but not the ruffled border although they showed similar cytoplasmic features to those of MGCs responding to HAP200. They merely extended short slender cytoplasmic processes to HAP1250. These results suggest that although osteoclast-like MGCs respond to HAP implanted in the bone, the development of the ruffled border-clear zone system depends on physicochemical properties of HAP.     

Surface Hardening of Carbon Steel Using High Powered YAG Laser

A high powered YAG laser with kaleidoscope for surface modification was applied to the surface hardening of carbon steels containing 0. 18-0.54 wt% C without the absorbents, and the relationships between laser processing and surface hardening were investigated by hardness and microstructure. The structure of the hardened zone underwent complete martensitic transformation in all of the carbon steels tested, and its hardness increased with greater carbon content. Under identical irradiated conditions, the hardened zone expanded with increasing carbon content. A hardened zone extending from the surface to a depth of 1.0 mm was obtained at a laser power of 1.0 kW and a scanning speed of 1 mm/sec. It was found that in the surface hardening of carbon steels, a high powered YAG laser can be used to control the hardened zone by selecting the appropriate irradiation conditions, however, the hardened zone was affected by the assistant gas and the flow rate.     

Training techniques for neural network applications in ATM

The main problems of adaptive ATM quality of service (QoS) control methods using neural networks were the exponentially wide range of the output target and the real-time training data sampling. But new practical techniques to overcome these problems may open new neural network applications. In this article, the framework of connection admission control (CAC) is described as a typical example of neural-network-based QoS estimation and two practical techniques, called relative target method and virtual output buffer method, are presented to enhance the neural network performance in CAC