Proof-testing and probabilistic lifetime estimation of glass fibers for sensor applications

The mechanical reliability of sensing glass fiber is one of the important problems in the practical use of fiber-optic sensors. To ensure long-term reliability on a mass-production level, a method of proof-testing is applied to a sensing glass fiber that will be subjected to mechanical deformation in its service situation. We propose to employ a higher strain level (screening level) in the proof-testing with a fiber-recoating technique that can suppress excessive damage during the testing. We consider a standard lifetime of 15 years of automotive applications and ensure a practical level of failure probability by a model calculation by using the strength data of a prototype fiber with the method of fracture-mechanics theory.     

Familial hypoparathyroidism: identification of a novel gain of function mutation in transmembrane domain 5 of the calcium-sensing receptor

Activating mutations of the extracellular calcium (Ca2+e)-sensing receptor (CaR) gene, mostly in its extracellular domain, can cause both familial and sporadic hypoparathyroidism. We report a Japanese family with severe hypoparathyroidism with pretreatment serum calcium (Ca) levels of 4.9-5.9 mg/dL. The proband presented with a seizure at 6 days of age. Her older brother and mother, who had also experienced seizures and tetany, respectively, likewise had hypoparathyroidism. A heterozygous missense mutation substituting a cysteine for the phenylalanine normally present at codon 788 (F788C) was identified in the CaR's fifth transmembrane domain and was shown to cosegregate with the disease. The mutation was absent in DNA from 50 control subjects. Analysis of the functional properties of the mutant receptor was carried out in transiently transfected HEK293 cells loaded with fura-2 by assessing Ca2+e-evoked increases in the cytosolic calcium concentration (Ca2+i). There was a leftward shift in the concentration-response curve for the mutant receptor [EC50 (effective concentration of Ca2+e producing half of the maximal Ca2+i response, 2.7 +/- 0.1 vs. 4.1 +/- 0.1 mmol/L for the wild-type receptor]. HEK293 cells cotransfected with both the wild-type and mutant CaRs (to mimic the heterozygous state in affected family members) showed an EC50 (3.0 +/- 0.1 mmol/L) similar to that of the mutant CaR alone. Thus, we confirm that 1) a gain of function mutation in the fifth transmembrane domain of the CaR causes severe familial hypoparathyroidism by rendering the receptor more sensitive than normal to activation by Ca2+e; 2) some patients in the family do not experience seizures despite their severe hypocalcemia; and 3) this condition needs to be differentiated from other causes of hypoparathyroidism.     

Liquid film dryout in a boiling channel under flow oscillation conditions

A simple theory was developed to elucidate the influence of sinusoidal oscillation of the inlet flow rate on the occurrence of liquid film dryout in an annular two-phase flow regime in a boiling channel. The theory assumes that the critical heat flux (CHF) under an oscillatory condition can be calculated from values in steady states provided that the effect of axial mixing of the liquid film is appropriately considered. The trends of CHFs calculated using a one-dimensional three-fluid model and those experimentally measured under atmospheric pressure were in reasonable agreement with the proposed theory. However, the CHF values measured under oscillatory conditions were usually higher in the experiment than in the numerical simulation, which indicated that axial liquid transport induced by disturbance waves might enhance axial mixing of the liquid film.     

Nanosecond High Voltage Pulse Generator Using Water Gap Switch for Compact High Power Pulsed Microwave Generator

Nanosecond and sub-nanosecond high voltage pulses can provide new applications. A cancer treatment by an ultra-short pulse high electric field is one of them. High power pulsed microwave has been proposed to apply the high electric field for that treatment. This work focuses on the design of a compact high power pulsed microwave generator using a nanosecond pulse power generator for the cancer treatment. To obtain fast rise time of voltage and current for nanosecond pulses, a switch has to have low inductance. Water gap switches have this property. Since water has a dielectric strength exceeding 1 MV/cm, gap distances for switching can be reduced to several hundreds of micrometers, and still allow switching of tens of kV. The narrow gaps allow us to reduce the switch inductance. In this study, the water gap switch was built in a Blumlein pulse forming line. The Blumlein line was designed to provide a pulse of 1 ns and to match an impedance to 16 Omega of an antenna. By using the water gap switch in the Blumlein line, the voltage rise time obtained approximately 750 ps at 13 kV of a peak pulse voltage. An electromagnetic wave was radiated underwater by the loop antenna. A measuring antenna at 0.15 m and 0.4 m from the radiating antenna caught electric field intensities of 116 kV/m and 32 kV/m, respectively. A frequency element of 250 MHz had higher intensity.     

High incidence of breakthrough varicella observed in healthy Japanese children immunized with live attenuated varicella vaccine (Oka strain)

In order to know the rate of occurrence of varicella among vaccinees (breakthrough varicella: BV), questionnaire postcards were sent to 593 healthy children who had received varicella vaccine (Oka strain) from March 1987 to December 1989. The questionnaire survey was repeated once a year until January 1996. The annual attack rate from the 1st to 3rd questionnaire was approximately 12%: however, from the 5th to 8th one it was 1-4%. To February 1996, the cumulative attack rate was 157/459 (34.2%). This rate was comparable to that among vaccinees who had confirmed seroconversion; namely, 51/132 (38.6%). These rates are much higher than those reported by other authors. All BV cases were clinically mild; even subjects who had received the vaccine 7 years prior to the disease showed mild symptoms. The high incidence may be partly explained by the regional epidemiology of varicella. The decrease in annual incidence with time after vaccination may be due to the following reasons: some vaccinees remained free from BV owing to reinforcement of their immunity from subclinical infection of varicella-zoster virus (VZV) and others from diminution of opportunity for exposure to VZV with increasing age. Varicella vaccine seems to be effective in modifying the symptoms of varicella, but not potent enough in protecting from VZV infection.     

Characteristics of visual feedback in postural control during standing.

In the present study, the visual feedback system in postural control was investigated. To suppress the vestibular and proprioceptive feedback paths, a subject stood on a force-measuring plate with a fixed back support. Because the subject's body was immovable under these conditions, the subject controlled a computer model which simulated body dynamics. Information on the sway angle of the model was fed visually. Under this condition, frequency response functions for the ankle moment in response to the sway angle were calculated. The experimental results suggest that the visual feedback system contains a large time delay and, consequently, the visual system does not by itself allow a subject to maintain an upright posture. Index Terms- Feedback control, frequency characteristics, identification, posture, visual sensory feedback.     

Industrial Applications of Pulsed Power Technology

A review of mainly the past two years is undertaken of the industrial applications of pulsed power. Repetitively operated pulsed power generators with a moderate peak power have been developed for industrial applications. These generators are reliable and have low maintenance. Development of the pulsed power generators helps promote industrial applications of pulsed power for such things as food processing, medical treatment, water treatment, exhaust gas treatment, ozone generation, engine ignition, ion implantation and others. Here, industrial applications of pulsed power are classified by application for biological effects, for pulsed streamer discharges in gases, for pulsed discharges in liquid or liquid- mixture, and for material processing.     

A field life prediction model of electronic modules corroded by S8 gas released from rubber ducts in-vehicle engine rooms

A model which predict the field life of electronic modules corroded by S₈ gas in vehicle engine rooms is constructed. The in-vehicle module field life is predicted from the accelerated test results of module alone and the measured results of in-vehicle module field environment conditions. In the modules, a circuit substrate with Ag wiring is placed on a baseplate within a housing and sealed with silicone. The S₈ gas is produced by the release of the free sulphur of rubber ducts in engine room at the maximum temperature holding time after engine stop. This S₈ gas permeates the silicone seal and corrodes the Ag wiring. The ratio of the corroded part thickness to the initial thickness of the Ag wiring increases with the increase of the number of engine start/stop cycles. The calculated results coincide well with the observed results of the corrosion thickness in an actual vehicle.     

Spinal and femoral bone mass accumulation during normal adolescence: comparison with female patients with sexual precocity and with hypogonadism

Since the attainment of higher bone mineral density (BMD) is a crucial strategy in preventing age-related bone loss and consequent fracture, we determined when bone mass of the lumbar spine (L2-L4) (g/cm2) and femoral neck (g/cm2) reaches its peak in healthy Japanese subjects and examined the influence of early exposure to estrogen and estrogen deficiency on BMD. We also determined the volumetric BMD, termed bone mineral apparent density (BMAD), of the lumbar spine and femoral neck. Using dual-energy x-ray absorptiometry (DXA) (Hologic QDR-1000), we measured BMD of both the lumbar spine and the femoral neck in 31 healthy children aged 2-11 yr, 269 children (138 males and 131 females) aged 13-19 yr, 12 men and 12 women aged 20-34 yr as adult controls, 11 patients with female central sexual precocity, and 3 patients with female primary hypogonadism. Because the densitometric data obtained from DXA are strongly influenced by the size of the bone in growing subjects, the volumetric BMAD (g/cm3) of the vertebral cube (L2-L4) and femoral neck were determined: BMAD (g/cm3) = BMD (g/cm2)/square root of scanned area (cm2) for the lumbar spine and by BMAD = BMD/width for the femoral neck. The BMD, both lumbar spine and femoral neck, nearly reached its peak at age 14.5-15 yr in girls and 16.5-17 yr in boys when compared with adult normal values. The difference in this age between sexes is identical to the difference in age at sexual maturation. BMD in patients with sexual precocity was high compared to age-matched controls, whereas patients with primary hypogonadism showed lower lumbar apparent BMD, and the increase in lumbar BMAD (g/cm3) was noted after the progression of puberty in healthy children, probably suggesting the importance of sex steroids in the increase of BMD and lumbar BMAD in both sexes. The girls with earlier menarche showed higher lumbar BMD at age 18 and 19 yr. For the femoral BMAD, there was no significant relationship between this value and age in girls. We conclude that peak bone mass is mainly achieved by late adolescence in Japanese as in Caucasians and that pubertal progression and probably estrogen itself play a crucial role in accumulation of bone mass in females.     

Characteristics of somatosensory feedback in postural controlduring standing

In the present study, the function of the somatosensory feedback system in postural control was investigated. For the sake of simplicity the present study considered only balancing in the anteroposterior direction using the ankle strategy, in which the ankle moment is mainly used to maintain balance. To suppress the vestibular and visual feedback paths, a subject stood on a force-measuring platform with a fixed back support. Because the subject's body was immovable under these conditions, the subject controlled a computer model that simulated the subject's load at the ankles, Information about the sway angle of the model was fed through the somatosensory feedback path. Frequency response functions of the ankle moment in response to the sway angle were calculated. The experimental results suggest that the human somatosensory feedback system has derivative characteristics and, consequently, can maintain an upright posture by itself. The results were compared with those of previous studies on vestibular and visual feedback systems. The comparison reveals that subject-to-subject variance in the somatosensory system is significantly smaller than that in the other systems. This may indicate that the somatosensory feedback is the most automatic of the systems and plays a dominant role when a subject maintains an upright posture using the ankle strategy