Real time signal processing in the clinical setting

We routinely use a variety of real time signal acquisition, enhancement, and display techniques in the operating room to provide the surgeon with functional information. This enables reduction of surgical morbidity in cases which present a significant risk to the nervous system. Here we present regression based signal processing algorithms which produce considerable signal-to-noise-ratio enhancement with corresponding reduction in the time required to obtain an interpretable neurophysiological signal. We also present the approach we have applied to fault tolerance and distributed data display for our workstation cluster environment.     

Nocturnal evolution of respiratory effort in obstructive sleep apnoea syndrome: influence on arousal threshold

It has been recently described that the overnight increase in maximal end-apnoeic oesophageal pressure (P(oes,max)), considered as an index of the arousal threshold to occlusion, mostly contributes to apnoea lengthening during the night. However, the rise in apnoea duration could also be caused by changes in hypoxaemia, chemosensitivity and upper airway resistance. To better define the relative contributions of each of these factors, we examined the recordings of nine patients. Before apnoea, the mean pulmonary resistance at peak inspiratory flow (RPIF) was computed. During apnoea, all swings in oesophageal pressure (P(oes)) were measured to define the P(oes,max), the increase from the minimum to the maximum (deltaP(oes)), the rate of increase in P(oes) (RP(oes)) and the P(oes) at the first occluded breath (P(oes,1)). A gradual and significant increase in apnoea duration (p=0.02), P(oes,max) (p=0.02) and deltaP(oes) (p=0.006) was present across the night without any changes in oxygen saturation, RPIF, and P(oes,1). The slope of increase in P(oes,max), apnoea duration and deltaP(oes) was correlated with the apnoea/hypopnoea index. We conclude that in obstructive sleep apnoea, the nocturnal rise in apnoea duration is attributable more to an increase in the arousal threshold related to apnoea recurrence than to changes in chemosensitivity and upper airway resistance.     

The other side of scavenger receptors: pattern recognition for host defense

Scavenger receptors bind modified lipoproteins and may play an important role both in normal and in pathological lipid metabolism. A number of different classes of scavenger receptors have been identified and several of these are multiligand receptors. Studies, both in vitro and in vivo, have indicated that at least some of these scavenger receptors may serve as pattern recognition receptors because they are able to bind a wide variety of pathogens. As a consequence, they may play key roles in innate immunity and host defense.     

Automated tuning of an electronic circuit board using the artificial neural network approach

Manufacturing of electronic circuits for microwave communication boards often requires tuning of different circuit characteristics by manual adjustment of several trimmer components, including the trimmer's resistance and capacitance. This manual tuning process was automated by applying the artificial neural network modeling approach. In the considered tuning process, which required manual adjustment of a set of trimmers, multiple specification criteria had to be satisfied by several trimmer rotations. The tuning process was described in terms of three independent steps: the circuit output measurement, trimmer selection, and trimmer rotation. The trimmer selection was performed by a semi-supervised neural network, which learned the patterns of circuit characteristics and the deviations between the ideal and practical outputs. Another network was developed for determination of trimmer rotation rate. The results, based on computer simulation of the tuning process, showed that the developed system improved performance of the tuning process, allowing for automation of the microwave circuit board tuning task in a real manufacturing environment.     

NeuroNet: collaborative intraoperative guidance and control

Neurophysiological monitoring assesses CNS structure function relationships during surgery. NeuroNet supports remote performance of this task through real time multimodal data processing and multimedia network communication. The system is fully integrated, transparently combining the collection, processing, and presentation of real time data sources, including all physiological monitoring functions, with non real time functions and extensive online database information. Workstations are mounted in instrumentation racks and configured with appropriate electronics to support various data acquisition tasks including electroencephalograms (EEGs), electromyograms (EMGs), and multimodality evoked potentials. Multiple racks can be used in parallel on the same case if the number of variables to be monitored exceeds the capacity of a single tack. The data acquired on these systems is transparently accessible, in real time, across the network for both review and analysis     

Determination ofp-cymene-2,3-diol, thymol, and carvacrol in different foodstuffs

p-Cymene-2,3-diol, carvacrol and thymol are components of thyme that exhibit antioxidant activities. The concentration of each substance was determined in different foodstuffs containing thyme extract. The stabilities ofp-cymene-2,3-diol, carvacrol and thymol were examined by heating lard containing thyme extract at temperatures from 80 °C to 160 °C.     

Moderately doped NMOS (M-LDD)-hot electron and current driveoptimization

Short-channel NMOS transistors with moderately doped drain (10¹⁴ cm^-2), and variable sidewall oxide spacer thickness were fabricated and studied. The sensitivities of hot carrier degradation, current drive capability, and other device parameters to the sidewall spacer thickness were measured and evaluated. The results clearly indicate that a moderately doped drain (M-LDD) provides a stable and well-optimized device, compared to a conventional LDD transistor with substantially lower implant dose. A simple model, explaining the observations, is proposed and discussed