Decreasing the number of test specimens by utilizing both fracture stress and fracture location for the estimation of Weibull parameter

In a bending load test for brittle materials, such as ceramics for spacecraft and aircraft, decreasing the number of test specimens required is a crucial problem. This paper discusses the effectiveness of using the information of both fracture stress and fracture location to decrease the number of specimens required to obtain the same precision as the Weibull estimator. The following results were obtained: It was found that by adding the fracture location information, the precision of the Weibull parameter estimation under the optimal design became 1.5–1.9 times better compared with the case of using only the fracture stresses. This means the number of samples necessary to attain the same precision becomes 1/1.5–1/1.9. Tables and figures which give information on the number of samples necessary to attain the required precision are given.     

Volumetric properties of mixtures of 1,4-dioxane and water at high pressures

Densities of aqueous of 1,4-dioxane have been measured at temperatures from 298 to 348 K and at pressures up to 40 MPa by a vibrating-tube method. Molar volumes obtained with an estimated uncertainty of ±0.2°,% are correlated with pressure by the Tait equation within the experimental uncertainty. Pressure and composition dependences of the excess molar volume, partial molar volume, and isothermal compressibility are determined and they are compared with those of other aqueous solutions.     

Acute myocardial infarction during pregnancy caused by coronary artery spasm

A 33-year-old pregnant woman suffered from acute anteroseptal myocardial infarction at the 19th gestational week. Despite periodic attacks of myocardial ischaemia after admission, the coronary arteriograms under the use of nitroglycerin were normal. Thereafter, she remained free from the ischaemic events with diltiazem hydrochloride and delivered a healthy baby. The coronary arteriography at puerperium also showed no organic narrowing. However, the provocative test with acetylcholine chloride caused severe spasm of the left anterior descending coronary artery. These findings strongly suggest that acute myocardial infarction in this pregnant woman was caused by coronary artery spasm.     

Is it possible to differentiate between choledochal cyst and congenital biliary atresia (type I cyst) by antenatal ultrasonography?

Both choledochal cyst and congenital biliary atresia (type I cyst) may share the same ultrasonographic pattern. We report 2 cases which were shown to have cystic structures on the upper abdomen by antenatal ultrasonography. The size of the choledochal cyst found at 24 weeks' gestation increased steadily as gestational age advanced. But the size of the cyst in congenital biliary atresia found at 29 weeks' gestation remained unchanged throughout the remaining pregnancy. Cyst enlargement, therefore, may suggest the possibility of a choledochal cyst.     

Forming mental models in learning operating procedures for terminalequipment

People faced with an unfamiliar product or service tend to fall back on mental models based on analogical relationships with familiar products or services. Two experiments on the analogical relationships or metaphors that people might use when operating a communications terminal are described. In the first experiment, the role previously acquired operating knowledge has in determining the mental models people use when directory dialing with novel equipment is examined. In a second experiment, it is shown that an explicit appeal to an analogy between conventional mail and electronic mail can help users learn to use an electronic mail system, and make it easier for them to remember how to use the system as long as 90 days after initial exposure. It is concluded that the mental model is constructed only from the user's operating knowledge acquired as a result of past experiences, and the metaphor method is effective when the instructions are metaphorically taught     

A 64-Mb DRAM with meshed power line

A 64-Mb dynamic RAM (DRAM) has been developed with a meshed power line (MPL) and a quasi-distributed sense-amplifier driver (qDSAD) scheme. It realizes high speed, t_RAS=50 ns (typical) at V_cc=3.3 V, and 16-b input/output (I/O). This MPL+qDSAD scheme can reduce sensing delay caused by the metal layer resistance. Furthermore, to suppress crosstalk noise, a V_SS shield peripheral layout scheme has been introduced, which also widens power line widths. This 64-Mb DRAM was fabricated with 0.4-μm CMOS technology using KrF excimer laser lithography. A newly developed memory cell structure, the tunnel-shaped stacked-capacitor cell (TSSC), was adapted to this 64-Mb DRAM     

Regional bond strengths of self-etching/self-priming adhesive systems

Within the context of an extensive study of electroconvulsive therapy at the Psychiatric Clinic of the University of Bonn 15 patients suffering from therapy-resistant Major depression (DSM III-R) were examined with a detailed psychometric test battery, containing memory- and nonmemory tests. The test battery had been applied short time before, during and after the treatment with 10 ECT applied unilateral over the nondominant hemisphere. Comparing the test performances before and 1-2 days after the end of the series there were only few remarkable changes: a significant decrease was diagnosed exclusively in 30 min delayed recall of verbal items, while visual short-term memory and visual-constructive performance showed a significant improvement (in spite of unilateral stimulation on the right side). None of the other cognitive functions inclusively speed of performances and reaction time was detracted short time after the end of the ECT-treatment, instead all the measures improved albeit not significantly. Between responders to treatment (50% improvement in HAMD) and non-responders no significant differences neither before nor after the treatment were detected. The non-responders had in nearly all of the tests some better (but not significantly) results despite being older than the group of responders.     

Effects of cysteinyl-leukotriene receptor antagonist, thromboxane A2 receptor antagonist, and thromboxane A2 synthetase inhibitor on antigen-induced bronchoconstriction in patients with asthma

BACKGROUND: Leukotriene (LT) and thromboxane A2 (TXA2) receptor antagonists have been used in the treatment of asthma. OBJECTIVES: We examined the effects of an LT receptor antagonist, TXA2 receptor antagonist, and TXA2 synthetase inhibitor on bronchoprovocation test (BPT) in patients with mild-to-moderate atopic asthma. METHODS: BPT was performed four times in each of six asthmatics. Development of the immediate asthmatic reaction (IAR) and late asthmatic reaction (LAR) was confirmed on the first BPT (BPT1). After a 7-day washout period, an LT receptor antagonist (pranlukast, 450 mg/d), TXA2 receptor antagonist (seratrodast, 80 mg/d), or TXA2 synthetase inhibitor (ozagrel, 800 mg/d) was administered orally over 7 days at random using a cross-over method (BPT2-4). Blood levels of LTB4, LTC4, LTD4, 11-dehydrothromboxane B2, eosinophil cationic protein, and histamine were measured at reaction phases of pre-BPT, IAR, and LAR. RESULTS: Administration of pranlukast suppressed IAR by 80.5% (p < 0.0001) and LAR by 54.6% (p = 0.0391). Ozagrel significantly suppressed IAR by 39.5% (p = 0.0413), but the fall in FEV1 was >20% (21.56+/-4.173%). Seratrodast did not suppress IAR or LAR. Blood levels of chemical mediators did not correlate with the suppressive effects of the tested drugs. CONCLUSIONS: The LT receptor antagonist was considered to be the most effective. LT might play a more important role in the pathogenesis of asthma than TXA2. Our data showed that measurement of blood levels of chemical mediators is not useful in identifying the pathogenic mechanisms of asthma.     

Principle and operation of a new type motor consisting of piezoelectric device and strain wave gearing

The authors have developed a new type of motor consisting of a piezoelectric device and strain wave gearing, and is called a piezoelectric motor. This is a first step in realizing a low-speed, small-size and lightweight motor. The principle of the motor is that the traveling wave is produced by piezoelectric devices and displacement conversion devices without mechanical resonance, and the torque to rotate the motor is generated by a mechanism of strain wave gearing (circular spline and flexspline) without using friction. The motor is operated at variable frequency and its rotational position (angle) is controlled in open-loop because it is basically a synchronous motor. In this paper, the structure and principle of the proposed motor are explained and the driving method and the mechanical characteristics of an experimental motor also are described. The results are as follows:

• 1 The realizability of the proposed piezoelectric motor is verified experimentally. The experimental motor operates at 2920 steps per revolution, and its speed range is 0 to 960 pps [or 0 to 20 (rpms)].
• 2 The torque characteristics are clarified qualitatively.
• 3 The generated torque of the experimental motor is small (less than 0.03 Nm) and therefore the improvement of the torque is an important subject hereafter.
• 4 It is possible to construct the motor with nonmetallic material. This fact is considered to facilitate obtaining a means to lighten the weight of the motor in the future.