Reliability behaviour of electronic components as a function of time

Considerable attention has been paid recently to the behaviour of the hazard rate function h(t) as a function of time. This discussion has led to a lot of speculation as to the shape of the traditional ‘bathtub’ curve showing failure or hazard rate as a function of time. Studies at the International Electronics Reliability Institute (IERI) at Loughborough University of Technology, in the United Kingdom, have recently been examining in detail the database created from field failure returns on a wide spectrum of electronic components. These components are in equipment subject to a spread of environmental conditions. The database created has been exercised with particular reference to the behaviour of MOS Ics, rectangular connectors, bipolar transistors and pn-junction diodes. Data has been analysed using pooled information from a wide variety of sources and also from two specific environmental conditions, ground benign and ground mobile. The results of this analysis are presented and the failure intensities as a function of time are given at 1000 hour intervals up to a total time of 21,000 hours. Confidence limits at the 95 per cent X² level are also given. The results show a rapidly falling failure intensity for the first few thousand hours and after this time the failure intensity appears to be relatively constant given the accuracy obtainable with the data available.     

Allergic fungal sinusitis in the southeastern USA: involvement of a new agent Epicoccum nigrum Ehrenb. ex Schlecht. 1824

The purpose of this study is to find the correlation between middle latency auditory evoked potentials (MLAEP) and sound activated single photon emission computed tomography (SPECT) studies. This study was performed on six normal right-handed volunteers with a mean age of 35.2 +/- 7.6 years, using the split-dose technique. First, a SPECT study was performed on subjects in blinded, awake and silent states. After bilateral ears were stimulated with a click sound, MLAEP and a second SPECT study were performed. Subtraction of the first SPECT from the second SPECT revealed a statistically significant increase of cerebral blood flow (CBF) in the bilateral superior temporal region. Bilateral Na amplitudes of MLAEP had a statistically significant and good correlation with the percentages of CBF changes in the bilateral superior temporal region. The superior temporal cerebral blood flow activation can be expressed by electrophysiological activation. Moreover, correlation during the left Na components and left frontal and occipital lobe are discussed.     

Predicting slag viscosities in metallurgical systems

Slag viscosity is a major process variable for most pyrometallurgical smelting and refining process operations. While extensive measurements have been made of slag viscosities, it is not practicable to provide data on all the possible combinations of compositions and process conditions encountered in metallurgical practice. This article reviews the mathematical models that have been developed to predict slag viscosities and provides some advice on the factors to be considered in their selection and use.     

Increased neural activity in transgenic mice with brain IGF-I overexpression: a [3H]2DG study

To evaluate whether insulin-like growth factor-I (IGF-I) modulates neural activity in vivo, relative levels of brain [3H]2-deoxyglucose (2DG) uptake were compared in adult behaving and anesthetized wild type (wt) mice, and transgenic (Tg) mice with either brain IGF-I overexpression or ectopic brain expression of IGF binding protein-1 (IGFBP-1). Overall, awake behaving IGF-I Tg mice showed significant increases in brain 2DG uptake compared with wt and IGFBP-1 Tg mice. These differences were eliminated after anesthesia. 2DG uptake was similar in awake behaving, and anesthetized wt and IGFBP-1 Tg mice. Our observations thus suggest that IGF-I increases neural activity levels in vivo, and that it is not involved in regulating glucose consumption in the adult brain.     

Neurological and psychiatric predictors of mortality in patients with Alzheimer disease in California

OBJECTIVE: To determine whether neurological and psychiatric symptoms predict survival time among patients with Alzheimer disease (AD) after adjusting for the influence of sociodemographic variables, health conditions, and dementia severity separately for men and women. DESIGN: The sample consisted of 936 men and women diagnosed as having probable or possible AD at 1 of 7 Alzheimer's Disease Diagnostic and Treatment Centers throughout California from 1986 through 1990. Data on dementia severity, comorbid conditions, and demographic characteristics were collected at the time of AD diagnosis. Data on vital status and dates of death were obtained by linking the patient file to several administrative databases maintained by the California State and federal governments. The mean length of follow-up was 31 months. Data were analyzed with Kaplan-Meier survival curves and Cox proportional hazards models. RESULTS: Men had shorter survival times than did women (log-rank test, 30.93, P < .001). Among men, but not women, survival times were negatively associated with selected neurological and psychiatric symptoms. Among women, but not men, a history of cardiovascular conditions was associated with poorer survival. CONCLUSIONS: Patterns of survival and predictors of survival time among patients with AD differ by sex. Future studies of survival and progression of AD need to examine men and women separately.     

Laryngeal sarcomatoid carcinoma: clinical, histological and immunohistochemical study of four cases

A 1488-bp fragment of bovine retina guanylate cyclase B gene encoding the catalytic and dimerizing domains as well as part of the protein kinase domain was expressed in Escherichia coli cells. The expression product was obtained as inclusion bodies and solubilized in 6 M guanidine hydrochloride. The fragment of guanylate cyclase B is a dimer close in catalytic activity to the native enzyme.     

Eigenface-domain super-resolution for face recognition

Face images that are captured by surveillance cameras usually have a very low resolution, which significantly limits the performance of face recognition systems. In the past, super-resolution techniques have been proposed to increase the resolution by combining information from multiple images. These techniques use super-resolution as a preprocessing step to obtain a high-resolution image that is later passed to a face recognition system. Considering that most state-of-the-art face recognition systems use an initial dimensionality reduction method, we propose to transfer the super-resolution reconstruction from pixel domain to a lower dimensional face space. Such an approach has the advantage of a significant decrease in the computational complexity of the super-resolution reconstruction. The reconstruction algorithm no longer tries to obtain a visually improved high-quality image, but instead constructs the information required by the recognition system directly in the low dimensional domain without any unnecessary overhead. In addition, we show that face-space super-resolution is more robust to registration errors and noise than pixel-domain super-resolution because of the addition of model-based constraints.