European Minor Constituent Radiometer: A New Millimeter Wave Receiver for Atmospheric Research

EMCOR is a heterodyne receiver for the frequency range of 201 to 210 GHz. It has been designed for ground-based measurements of various minor constituents of the stratosphere involved in ozone chemistry. Since the aim was the detection of faint spectral lines, a superconducting tunnel junction has been chosen as mixer element and special care has been taken in developing the calibration unit of the system. The front-end is completed by a quasi-optical system, a solid state local oscillator with electronic tuning and a HEMT pre-amplifier. In the back-end an acousto-optical spectrometer is employed to analyse the signal. A PC controls the whole system. The instrument has been installed at a high mountain site in the Swiss Alps.     

Release of proinflammatory cytokines during pediatric cardiopulmonary bypass: heparin-bonded versus nonbonded oxygenators

BACKGROUND: Heparin bonding of the cardiopulmonary bypass (CPB) circuit may be associated with a reduced inflammatory response and improved clinical outcome. The relative contribution of a heparin-bonded oxygenator (ie, >80% of circuit surface area) to these effects was assessed in a group of pediatric patients. METHODS: Twenty-one pediatric patients undergoing CPB operations were assigned randomly to receive either a heparin-bonded oxygenator (group H, n = 11) or a nonbonded oxygenator (group C, n = 10) in otherwise nonbonded circuits. The two groups were similar in pathology, age, weight, CPB time, and cross-clamp time. Plasma levels of the cytokines tumor necrosis factor-alpha, interleukin-6, and interleukin-8, as well as terminal complement complex, neutrophils, and elastase, were analyzed before, during, and after CPB. RESULTS: Significant levels of tumor necrosis factor-alpha were not detected in either group. Plasma levels of all other markers increased during and after CPB compared with baseline. Plasma levels of interleukin-6 peaked in both groups 2 hours after the administration of protamine but remained significantly higher in group C 24 hours after operation. Plasma concentrations of interleukin-8 peaked at similar levels in both groups 30 minutes after protamine administration and returned to baseline thereafter. Levels of terminal complement complex and elastase peaked in both groups 30 minutes after protamine administration. Plasma levels of terminal complement complex were significantly higher at the end of CPB and after protamine administration in group C. Elastase levels were significantly higher 2 and 24 hours after CPB in group C. The ventilation time of patients in group H was significantly lower than that of patients in group C: 10 (range, 3 to 24) versus 22 (range, 7 to 24) hours, respectively (p < 0.01). CONCLUSIONS: The present study confirms the proinflammatory nature of pediatric operations and demonstrates a lessened systemic inflammatory response with the use of heparin-bonded oxygenators. This is achieved without bonding of the entire circuit, which could have significant cost-benefit implications by negating the need for custom-built heparin-bonded circuitry.     

Secondary structure mapping of an RNA ligand that has high affinity for the MetJ repressor protein and interference modification analysis of the protein-RNA complex

The secondary structure of an RNA aptamer, which has a high affinity for the Escherichia coli MetJ repressor protein, has been mapped using ribonucleases and with diethyl pyrocarbonate. The RNA ligand is composed of a stem-loop with a highly structured internal loop. Interference modification showed that the bases within the internal loop, and those directly adjacent to it, are important in the binding of the RNA ligand to MetJ. Most of the terminal stem-loop could be removed with little effect on the binding. Ethylation interference suggests that none of the phosphate groups are absolutely essential for tight binding. The data suggest that the MetJ binding site on the aptamer is distinct from that of the natural DNA target, the 8-base pair Met box.     

ARTIFICIAL NEURAL NETWORKS: PRINCIPLE AND APPLICATION TO MODEL BASED CONTROL OF DRYING SYSTEMS - A REVIEW

Abstract

This paper reviews the developments in the model based control of drying systems using Artificial Neural Networks (ANNs). Survey of current research works reveals the growing interest in the application of ANN in modeling and control of non-linear, dynamic and time-variant systems. Over 115 articles published in this area are reviewed. All landmark papers are systematically classified in chronological order, in three distinct categories; namely, conventional feedback controllers, model based controllers using conventional methods and model based controllers using ANN for drying process. The principles of ANN are presented in detail. The problems and issues of the drying system and the features of various ANN models are dealt with upto-date. ANN based controllers lead to smoother controller outputs, which would increase actuator life. The paper concludes with suggestions for improving the existing modeling techniques as applied to predicting the performance characteristics of dryers. The hybridization techniques, namely, neural with fuzzy logic and genetic algorithms, presented, provide, directions for pursuing further research for the implementation of appropriate control strategies. The authors opine that the information presented here would be highly beneficial for pursuing research in modeling and control of drying process using ANN     

Hearing aid outcome measures for children

The provision of appropriate amplification for a young hearing-impaired child is critical as the aided speech signal will be used for the development of speech and language. The purpose of this paper is to provide an overview of the complex issues surrounding the documentation of hearing aid outcomes in the pediatric population. In the first two sections of the paper, the unique characteristics and needs of the pediatric population and factors complicating the measurement of outcome are described in detail. The third section provides a review of literature on existing outcome measures for children and the fourth section is devoted to a discussion of alternative approaches. The final section is an overview of clinical and research needs in the area of hearing aid outcome measures for children.     

Subjective effects of peak clipping and compression limiting in normal and hearing-impaired children and adults

Despite many advances in hearing-aid signal processing, compression limiting and peak clipping are still used. To date, perceptual studies have been conducted only with adults. The current study was designed to investigate the clarity of peak-clipped and compressed speech for both adults and children. Subjects were 30 normal-hearing and 30 hearing-impaired individuals in three age ranges (7-9, 10-12, and 16-50 years). Stimuli were processed at 60, 70, 75, and 80 dB SPL using peak clipping and at 80 dB SPL using compression limiting. Paired-comparison measures were used to assess the clarity of sentences, and a signal-to-distortion ratio (SDR) based on a measure of coherence between input and output was computed for each condition. For the peak-clipping conditions, there was a decrease in perceived clarity as the input increased from 60 to 80 dB SPL. This perceptual continuum was most apparent for the normal-hearing adults. The normal-hearing 10-12 year olds and the hearing-impaired adults showed a similar, but less pronounced, pattern. In contrast, the remaining three subject groups showed minimal differences in perceived clarity across conditions. Surprisingly, only the two oldest normal-hearing groups showed a clear preference for compression limiting over peak clipping at the highest input level, and only their results were consistent with the pattern of coherence across stimuli. Judgments of clarity by the normal-hearing subjects correlated best with the SDR in the 500-2000-Hz range, while clarity judgments of the hearing-impaired subjects correlated best with the SDR below 1000 Hz.     

Characterisation of a chromatographically produced anti-D immunoglobulin product

A chromatographic fractionation method has been developed for the production of a liquid-stable anti-D immunoglobulin product for intravenous and intramuscular use. An immunoglobulin fraction, highly enriched with anti-D immunoglobulins, was isolated by cation-exchange column chromatography and further polished, first by anion-exchange chromatography, followed by an aluminium hydroxide gel treatment. The process includes two specific steps for virus inactivation and removal, namely S/D treatment and nanofiltration. The overall anti-D process yield is about 56%. The final product is stabilised with human albumin and glycine and placed in ready-to-use syringes. The anti-D product was shown to be stable in liquid state for at least 30 months at 4 degrees C.