Zhu Y

Insight into the dicrotic notch in photoplethysmographic pulses from the finger tip of young adults

This study aims to investigate arterial stiffness in selected young adults by non-invasively determining the characteristics of the photoplethysmographic dicrotic notch. A total of 15 volunteers participated in this study, divided into four groups by age and gender. Contour analysis was applied to analyse the photoplethysmographic dicrotic notch, including time-related and height-related parameters. The height of reflected wave, mirrored by the notch relative amplitude (NRA), was found to be significantly larger in the older group compared to the younger group (pu2009=u20090.016). The timing of the reflected wave, measured by three parameters, i.e. notch index (NI), notch latency (NL) and peak-to-notch latency (PTNL), significantly increased in the female group compared to the male group (all pu2009<u20090.02). The results confirm that arterial stiffness occurs in young adults, and demonstrate that a difference of arterial stiffness exists between young male and female. This study indicates that examining the characteristic notch of the PPG pulse could help in identifying differences of vascular activities.

Use of ANN and Complexity Measures in Cognitive EEG Discrimination

The purpose of this paper is to apply BP ANN to the discrimination of three kinds of subjects (clinical diagnosed 62 schizophrenic patients, 48 depressive patients and 26 normal controls) respectively in resting state with eyes closed and three cognitive tasks, with EEG complexity measures used as feature vectors. EEG activity is recorded from 16 scalp electrodes and recordings are digitized for off-line processing. Features vectors based on Lep-Ziv complexity and classification with ANN are implemented in Matlab6.5. The comparison between the results of classifying in four states is illustrated and discussed. The classification accuracies achieved are 60% and over. The results show that ANN is an effective approach for discrimination of these three kinds of objects both in baseline and some cognitive states

Spatial-Temporal Analysis of Face Processing Using an ERP Study of the Thatcher Illusion

A face with the inversion of eyes and mouth relative to the rest parts of the face looks grotesque when viewed upright but not when viewed upside down, which is called the Thatcher illusion. Brain studies indicate that this is caused by the disruption of facial information processing. However, the neural mechanism of the face processing is still ambiguous. In the current study, we investigated neural correlates of featural and configural processing in faces using a spatial-temporal analysis of event-related potentials (ERP). The results showed that the PI component was affected by face inversion but not by Thatcherization. For the N170 component, the inversion effect was salient while the Thatcherization effect interacted with orientation and hemisphere. A bilaterally distributed effect of Thatcherization was observed in inverted faces and a contrary difference was showed in upright faces. This indicated that the perceptual effect of Thatcher illusion does not parallel N170 component. Combining with the scalp topographies we come to a conclusion that the left occipito-temporal area of the brain is sensitive to featural information of visual face stimuli while the right area is sensitive to configural information.

Poincar&#233; plot analysis for pulse interval extracted from non-contact photoplethysmography

An analysis of pulse-to-pulse interval (PPI) derived from non-contact photoplethysmography (PPG) is performed using the Poincare plot technique. Eleven healthy volunteers participated in a protocol utilising both spontaneous and paced breathing methodologies with a customised non-contact PPG system to obtain adequate quality signals for a distance of 80 mm between source and detector. An adaptive trough-searching algorithm (ATSA) is developed to extract the PPI which is effective in the presence of artefact during non-contact PPG measurement. A Poincare plot for each 5 minute period of the protocol shows significant pattern differences between spontaneous and paced breathing measurements. Geometric parameters extracted from the Poincare plot are shown to be sensitive to breathing interval changes and are a useful indicator for the variation of pulse rate variability measured using non-contact PPG

Modeling the relation between muscle thickness and wrist angle based on bone-muscle lever model

Muscle modeling is a powerful tool to study the skeletal muscle, and can give a better perception of the mechanisms of muscular functions. In this study, a mathematical model was proposed based on the bone-muscle lever model to illuminate the non-linear relation between the thickness of extensor carpi radialis muscle and wrist angle. The ultrasound image, SEMG signals were synchronously sampled from the extensor carpi radialis muscle together with the wrist angle during the whole process of wrist extension and flexion to validate the model. The wrist angle was then calculated using the measured muscle thickness by this model. The overall mean correlation coefficient value was 0.96 ± 0.02, and the overall mean standard root mean square error was 5.82 ± 1.95, which were much better than the results of other regression methods. The results show that the wrist angle is well predicted by our model, and it suggests that this model is helpful to study the relationship between internal muscle structural changes and external limb behaviors.

Detecting the Determinism of EEG Time Series Using a Nonlinear Forecasting Method

The determinism of time series is investigated using a nonlinear non-parametric forecasting method. The goodness of prediction was estimated in terms of the prediction error of the predicted time series. A new definition of the prediction effect was made in the present study. Three typical kinds of time series were detected using our new method. In deterministic chaotic time series, good prediction was obtained in the new definition. However, for Gaussian random noise and schizophrenia EEG signal, the predictability could not found. We concluded that EEGs in schizophrenic patients were not deterministic