Determination of Test Intervals in Certain Repairable Standby Protective Systems

A System has associated with it a Safeguard such that whenever a failure in the Safeguard is detected, the System is shut down. The System is restarted as soon as the Safeguard is repaired. An example is a standby protective system attached to a nuclear power plant; as soon as failure is detected in the protective system the nuclear plant will be shut down until repair is completed. In order to insure that the Safeguard remains in the utmost state of readiness, the components of the Safeguard are periodically tested, and repaired if the test reveals a failure. In this paper we define a measure of readiness appropriate for the above systems and consider the problem of determining the testing frequency of the components of the Safeguard in such a way that an adequate level of readiness is maintained. As an illustration, the method is applied to a typical reactor-trip system.     

Local dynamics and synchronization in a granular glass

We follow over a long time sequence, the motion of individual particles in an experimental model of “glassy” granular material. In spite of the weak level of vibration applied to the packing, the particles display individual motion in the form of a sub-diffusive random walk followed by a standard diffusive motion. The statistical features of the random walk is examined in detail. Though the motion is tiny at the local granular level, we demonstrate collective synchronizations of the jump dynamics involving several tens of particles. This collective motion is directly related to the caging effect observed in other glassy systems. Through an analysis of the motion kinematics, we relate the granular motion to a collective “solid-like” dynamics keeping its coherence over the whole sub-diffusive domain.     

Workplace justice, citizenship behavior, and turnover intentions in a union context: Examining the mediating role of perceived union support and union instrumentality.

This study examined the relationship between workplace justice afforded by the grievance system and the union outcomes of citizenship behavior and turnover intentions and the mechanisms that underpin these relationships. Respondents (N?=?187) were members of a large public sector union in Singapore. Results revealed that perceived union support and union instrumentality fully mediated the relationship between the dimensions of workplace justice and citizenship behavior directed toward the union (OCBO) and citizenship behavior directed at other union members (OCBI). Union instrumentality partially mediated the procedural justice-turnover intentions relationship. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Efficacy of bronchodilators in the treatment of bronchiolitis

Bronchiolitis is a common respiratory infection affecting young children. Much controversy revolves around the efficacy of bronchodilators in the treatment of bronchiolitis. This study was conducted to address this issue. AIM: To determine the efficacy of bronchodilators in the treatment of bronchiolitis. METHOD: All children less than 2 years old with bronchiolitis were randomly assigned to receive nebulisations of Salbutamol, Ipratropium bromide or normal saline. A fourth group given only humidified oxygen without nebulisation were used as a control. RESULTS: Data were obtained for 120 patients. Fifty-one (42%) had respiratory syncytial virus (RSV) isolated from their nasopharyngeal aspirates. The demographic characteristics of the 4 groups were similar. There was no significant difference between the groups in terms of severity score, number of nebulisations required in the nebulised groups and the outcome as measured by the length of hospitalisation. CONCLUSION: The use of bronchodilators did not alter the course of the disease and is therefore not effective in the treatment of bronchiolitis.     

Propagation of uncertainties in problems of structural reliability

The problem of controlling a variable Y such that the probability of its exceeding a specified design limit L is very small, is treated. This variable is related to a set of random variables X_i by means of a known function Y = ƒ(X_i). The following approximate methods are considered for estimating the propagation of error in the X_i's through the function ƒ(·): linearization; method of moments; Monte Carlo methods; numerical integration. Response surface and associated design of experiments problems as well as statistical inference problems are discussed.     

Biosorption of cadmium ions using <Emphasis Type=Italic>Pleurotus ostreatus</Emphasis>: Growth kinetics,isotherm study and biosorption mechanism

The mycelial growth kinetics, cadmium biosorption capacity and main governing biosorption mechanism of Pleurotus ostreatus (oyster mushroom) have been determined in this study. The fungus mycelium exhibits a sigmoidal (S-shaped) growth curve in which the growth rates for the lag and exponential phases are 0.1 and 0.31 g/L·day, respectively. The grown fungus is subjected to elemental, infra-red and scanning electron microscopy-energy dispersive x-ray spectroscopy analyses, while biosorption data are fitted to established adsorption isotherm models, namely, Langmuir, Freundlich and Dubinin-Radushkevich. It is strongly suggested that the main governing mechanism involved is chemisorption due to good fitting of biosorption data to Langmuir and Dubinin-Radushkevich models with possibility of involvement of both ion exchange and complexation. Data presented in the study are very useful for design of future pilot- or industrial-scale biosorption water purification systems.     

Effects of extracellular calcium on electrical bursting and intracellular and luminal calcium oscillations in insulin secreting pancreatic beta-cells

The extracellular calcium concentration has interesting effects on bursting of pancreatic beta-cells. The mechanism underlying the extracellular Ca2+ effect is not well understood. By incorporating a low-threshold transient inward current to the store-operated bursting model of Chay, this paper elucidates the role of the extracellular Ca2+ concentration in influencing electrical activity, intracellular Ca2+ concentration, and the luminal Ca2+ concentration in the intracellular Ca2+ store. The possibility that this inward current is a carbachol-sensitive and TTX-insensitive Na+ current discovered by others is discussed. In addition, this paper explains how these three variables respond when various pharmacological agents are applied to the store-operated model.