Optimization of thin-film resistive-gate and capacitive-gate GaAs charge-coupled devices

The aim of the paper is to determine the speed of the neurological response to cerebral artery occlusion by monitoring transient changes in somatosensory evoked potentials (SEPs). SEPs, continuously monitored during temporary clipping of the middle cerebral artery (MCA) in anaesthetised cats, are analysed. The SEP signals are modelled by a quasi-periodic Fourier series, the coefficients of which are estimated with the aid of two adaptive least squares estimation algorithms. The energy levels at various harmonics throughout the protocol are obtained directly from the filter weights. Noise covariance is estimated from pre-stimulus recording, and the adaptation rate of the algorithm is adjusted sweep-by-sweep to accommodate transient changes in the pre-stimulus noise level. After the occlusion, a significant decrease (p < 0.05) in SEP amplitude is observed. The change in latency is not statistically significant (p approximately equal to 0.5). The spectral trends show a sudden decline in energy at all harmonics immediately following occlusion, although when the amplifier bandwidth is changed to 5-1500 Hz (from an initial setting of 30-1500 Hz), the fundamental frequency component of the SEP signal shows the greatest responsiveness to injury. The average time constant of the decline in amplitude resulting from MCA occlusion is only 10.6 +/- 4.0 s. It is concluded that rapid detection of cerebral artery occlusion and ischaemia may be feasible by continuously monitoring SEP signals and analysing transient changes in time and frequency domains.

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Detection of brainstem auditory evoked potential by adaptive filtering

Chan

Lam

Poon

et al. 1995

Med. Biol. Eng. Comput.

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A method of detecting brainstem auditory evoked potential (BAEP) using adaptive signal enhancement (ASE) is proposed and tested in humans and cats. The ASE in this system estimates the signal component of the primary input, which is correlated with the reference input to the adaptive filter. The reference input is carefully designed to make an optimal and rapid estimation of the signal corrupted with noise, such as ongoing EEG. With a good choice of reference input, it is possible to track the variability of BAEP efficiently and rapidly. Moreover, the number of repetitions required could be markedly reduced and the result of the system is superior to that of ensemble averaging (EA). To detect BAEP in cats, only 30 ensemble averages are needed to obtain a reasonable reference input to the adaptive filter, and, for humans, 350-750 ensemble averages are sufficient for a satisfactory result. Using the LMS adaptive algorithm, individual BAEP can be obtained in real-time.

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Optimization of thin-film resistive-gate and capacitive-gate GaAs charge-coupled devices

Cited by 9 publications

References 34 publications

Two-Dimensional Transient Simulation of Charge-Coupled Devices Using MINIMOS NT

Two-Dimensional Transient Simulation of Charge-Coupled Devices Using MINIMOS NT

Rapid measurement of somatosensory evoked potential response to cerebral artery occlusion

Detection of brainstem auditory evoked potential by adaptive filtering

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