Chris Heneghan

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We used a variety of statistical measures to identify the point process that describes the maintained discharge of retinal ganglion cells (RGC's) and neurons in the lateral geniculate nucleus (LGN) of the cat. These measures are based on both interevent intervals and event counts and include the interevent-interval histogram, rescaled range analysis, the(More)
Stochastic fractal signals can be characterized by the Hurst coefficient H, which is related to the exponents of various power-law statistics characteristic of these processes. Two techniques widely used to estimate H are spectral analysis and detrended fluctuation analysis ~DFA!. This paper examines the analytical link between these two measures and shows(More)
We propose a key generation method for RSA moduli which allows the cost of the public operations (encryption/verifying) and the private operations (decryption/signing) to be balanced according to the application requirements. Our method is a generalisation of using small public exponents and small Chinese remainder (CRT) private exponents. Our results are(More)
Rectification of the electromyographic (EMG) signal is a commonly used pre-processing procedure that allows detection of significant coherence between EMG and measured cortical signals. However, despite its accepted and wide-spread use, no detailed analysis has been presented to offer insight into the precise function of rectification. We begin this paper(More)
To investigate the presence of the postulated shearing motion in the micromechanics of the inner ear during sound stimulations we measured the vibratory response of the tectorial membrane and the reticular lamina in the third cochlear turn in an isolated temporal bone preparation using confocal laser heterodyne interferometry. The mechanical response of the(More)
The methods of active contours (“snakes”) and level sets were applied to images of the retina in order to locate the outer boundary of the optic disk. A gradient-vector-flow based active contour was used as it performed well over a large range of initial conditions. Images were pre-processed to lessen the influence of blood vessels on boundary detection.(More)
Automated detection of sleep apnoea from the surface ECG is a challenge with potentially significant clinical benefit. The objective of this study is to explore a possible relation between P-wave shape changes and the presence of Obstructive Sleep Apnoea (OSA) episodes in ECG records. Our working hypothesis is that apnoea-related phenomena (e.g., hypoxia,(More)
We investigate two signal processing methods, time and frequency-based approaches, for non-contact cardiac detection. A 5.8-GHz Doppler radar sensor was used for non-contact measurement of respiration and heart rate from stationary and semi-stationary subjects at a distance of 0.5 to 1.5 meters. We report on the accuracy of the heart rate measurements(More)
Orthogonal frequency division multiplexed systems are particularly prone to errors due to clipping, since they typically have high peak-to-average power ratios. In this paper, we propose a more efficient clipping mitigation technique based on quasi maximum-likelihood detection which gives approximately 3 dB gain for the SER of 2 /spl times/ 10/sup -3/ and(More)
The study of human cognition, and preoperative functional brain mapping, are facilitated through the use of magnetoencephalography (MEG). However, the noise present in such recordings is significant relative to the signals of interest. To circumvent this issue multiple trials are performed for the same task and an ensemble average is performed to increase(More)