Sleep onset estimator: evaluation of parameters

The electroencephalographic (EEG) alterations during the human sleep onset (falling asleep period) has been evaluated by several studies in the past. However, the analysis part has been limited due to standard signal processing methods. This paper has attempted to evaluate a number of advanced parameters for improved sleep onset estimation, such as EEG non-parametric coherence, power frequency and spectral band power. These parameters can be utilised in an on-line algorithm design for neurofeedback applications

Influence of sinusoidally modulated visual stimuli at extremely low frequency range on the human EEG Activity

The purpose of this study was to investigate whether sinusoidally modulated visual stimuli at extremely low frequencies (ELF) of 50, 16.66, 13, 10, 8.33 and 4Hz could influence the changes in EEG activity in 33 human subjects. An improved design of visual stimulator system has addressed an issue of electrical interference from electrical signals driven by LED arrays onto simultaneously recorded EEG. A comparison between 1 and 3-Way ANOVA was performed in order to evaluate whether visual stimuli at ELFs could influence the EEG in humans to compliment the currently active medical research in seasonal affective disorder (SAD) and photic driving. The results revealed that under evaluation of 1 and 3-Way repeated-measures ANOVA tests, the Theta, Alpha2 and Gamma EEG bands exhibited a common significant difference between ELF visual stimuli

Decomposition of evoked potentials using peak detection and the discrete wavelet transform

A new method of viewing evoked potential data is described. This method, called the peak detection method, is based on singularity detection using the discrete wavelet transform. The peaks and troughs of raw visual evoked potential data are identified and characterized using the algorithms of this method, resulting in a linear decomposition of the recording into sets of individual peaks. The individual peaks are then added together, averaged and compared to the ensemble average signal. The peak detection method correlates strongly to the ensemble average showing that this method retains the same evoked potential signal profil

Alterations in human EEG activity caused by extremely low frequency electromagnetic fields

This study has investigated whether extremely low frequency (ELF) electromagnetic fields (EMFs) can alter human brain activity. Linearly polarised magnetic flux density of 20Â-T (rms) was generated using a standard double Helmholtz coils and applied to the human head over a sequence of 1 minute stimulations followed by one minute without stimulation in the following order of frequencies 50, 16.66, 13, 10, 8.33 and 4Hz. We collected recordings on 33 human volunteers under double-blind counter-balanced conditions. Each stimulation lasted for two minutes followed by one minute post-stimulation EEG recording. The same procedure was repeated for the EMF control sessions, where the order of control and exposure sessions was determined randomly according to the subject's ID number. The rest period between two conditions (exposure and control) was 30 minutes. The results indicate that there was a significant increase in Alpha1, Alpha2, and Beta1 at the frontal brain region, and a significant decrease in Alpha2 band in parietal and occipital region due to EMF exposure

The effect of GSM-like ELF radiation on the alpha band of the human resting EEG

Mobile phone handsets such as those operating in the GSM network emit extremely low frequency electromagnetic fields ranging from DC to at least 40 kHz. As a subpart of an extended protocol, the influence of these fields on the human resting EEG has been investigated in a fully counter balanced, double blind, cross-over design study that recruited 72 healthy volunteers. A decrease in the alpha frequency band was observed during the 20 minutes of ELF exposure in the exposed hemisphere only. This result suggests that ELF fields as emitted from GSM handsets during the DTX mode may have an effect on the resting alpha band of the human EEG

Power changes of EEG signals associated with muscle fatigue: The root mean square analysis of EEG bands

The paper reports a research conducted to determine changes in the electrical activity of the contralateral motor cortex of the brain that drives the maximum voluntary contraction (MVC) of the right adductor pollicis muscle (APM) after fatigue. The power changes of EEG signals after muscle fatigue were computed. In twenty-five subjects, EEG signals from the left motor cortical area (C3, FC3) were recorded simultaneously with EMG signals from the right APM, before and after exercise-induced fatigue. The root mean square (RMS) of the EEG bands (alpha, beta, and gamma) was calculated to determine the power changes of the EEG signals after right APM fatigue. The mean RMS of the EEG bands were increased during MVC of the fatigued right APM compared to the RMS value during relaxation before fatigue (p<0.05). The RMS value was seen to be greatest in the beta band, and lowest in the gamma band. The observed increase in the RMS of EEG bands during MVC of the fatigued right APM suggest an increase in the EEG signal power, which could reflect an increase in energy needed by the motor cortex to perform MVC in fatigued muscles, which might give an indication of neural fatigue in the motor cortex

Polychromatic angle resolved IBIC analysis of silicon power diodes

This paper describes both an experimental methodology based on the Ion Beam Induced Charge (IBIC) technique and the relevant interpretative model, which were adopted to characterize the electronic features of power diodes. IBIC spectra were acquired using different proton energies (from 1.2 to 2.0 MeV), angles of incidence, and applied bias voltages. The modulation of the ion probe range, combined with the modulation of the extensions of the depletion layer, allowed the charge collection efficiency scale to be accurately calibrated, the dead layer beneath the thick (6 micrometer) Al electrode and the minority carrier lifetime to be measured. The analysis was performed by using a simplified model extracted from the basic IBIC theory, which proved to be suitable to interpret the behaviour of the IBIC spectra as a function of all the experimental conditions and to characterize the devices, both for what concerns the electrostatics and the recombination processes.Comment: 24 pagese,10 figure

Hybrid approach to analysis of beta-sheet structures based on signal processing and statistical consideration

A number of biotechnology applications are based on protein design. For this design, the relationship between a proteins primary structure and its conformation is of vital importance. A beta-sheet is a common feature of a proteins two-dimensional structure; therefore, elucidating the principles governing beta-sheet structure and its stability is critical for understanding the protein-folding process. In the three-dimensional representation of protein molecules, C(alpha) carbon coordinates (carbon atom immediately adjacent to the carboxylate group) have often been employed instead of the complete set of coordinates for the corresponding residues. Using the C(alpha) carbon coordinates, we showed that particular amino acids are not randomly distributed within a beta-sheet structure. On the basis of a new statistical approach for the analysis of a spatial distribution of amino acids in a protein, presented by their physico-chemical parameters, the electron-ion interaction potential (EIIP) and hydrophobicity, are described here. The relationship between amino acid positions inside the beta-sheet and the EIIP and hydrophobicity parameters was established. The correlation between amino acid propensities related to the beta-sheet was examined using multiple cross-spectra analysis. We also applied the continuous wavelet transform for the analysis of selected beta-sheet structures using the EIIP and hydrophobicity parameters. The findings provide new insight into conformational propensities of amino acids for the adaption of beta-sheet structures

‘The International Teacher Leadership project,’ a case of international action research.

Copyright CARNThe paper arises from the International Teacher Leadership project, a research and development project involving researchers and practitioners in 14 European countries. The paper provides a conceptual exploration of the idea of teacher leadership and its role in educational reform, central to which is the idea that teachers, regardless of their level of power and organisational position, can engage in the leadership of enquiry-based development activity aimed at influencing their colleagues and embedding improved practices in their schools. The paper provides an outline of the project’s methodology which builds on that used in the Carpe Vitam Leadership for Learning project (Frost, 2008a). It is a form of collaborative action research which is highly developmental and discursive. It seeks to identify principles, strategies and tools that can be applied in a range of cultural settings. The paper includes a thematic analysis of the cultural contexts and policy environments of the participating countries in order to identify the obstacles to teacher leadership and to inform the nature of the support strategies employed