Search

The BBC is often said to have made a crucial contribution to the unity and morale of the British people during the Second World War. As Sian Nicholas shows in [...]

This article discusses the history of the political career of Winston Churchill beginning in 1900. It examines his role as a liberal political figure, both as a politician in shaping the government policy of Great Britain as well as during his time as the Prime Minister of Great Britain during the Second World War. it traces the history of his political thinking and actions beginning with his defection from the more conservative Tory party, continuing through his defection to the Liberal Party and then his return later on to the Tories again.

The article presents a study on the aspects of continuous wavelet transform (CWT) and discrete wavelet transform (DWT) as well as their application in the biomedical signal processing. It notes that CWT is fitted for high-resolution interrogation while DWT provides powerful methodologies where potent compression strategies are based. It concludes that wavelet transform is a flexible time-frequency decomposition tool which serves as groundwork of useful signal analysis and coding system.

Ventricular tachyarrhythmias are potentially lethal cardiac pathologies and the commonest cause of sudden cardiac death. Efforts to predict the onset of such events are based on feature extraction from the surface ECG. T-wave alternans (TWAs) are considered a marker of abnormal ventricular function that may be associated with ventricular tachycardia (VT) and ventricular fibrillation. A novel TWA detection algorithm utilizing the continuous wavelet transform is described in this paper. Simulated ECGs containing artificial TWA were used to test the algorithm that achieved a sensitivity of 91.40% and a specificity of 94.00%. The algorithm was subsequently used to analyze the ECGs of eight patients prior to the onset of VT. Of these, the algorithm indicated that five patients exhibited TWA prior to the onset of the tachyarrhythmic events, while the remaining three patients did not exhibit identifiable TWA. Healthy individuals were also studied in which one short TWA episode was detected by the algorithm. How- ever, closer visual inspection of the data revealed this to be a likely false positive result. [ABSTRACT FROM AUTHOR]

Background: We have developed an automated algorithm to allow the measurement of respiratory rate directly from the photoplethysmogram (pulse oximeter waveform). Aim: To test the algorithm's ability to determine respiratory rate in children. Methods: A convenience sample of patients attending a paediatric Accident and Emergency Department was monitored using a purpose-built pulse oximeter and the photoplethysmogram (PPG) recorded. Respiration was also recorded by an observer activating a push-button switch in synchronization with the child's breathing. The switch marker signals were processed to derive a manual respiratory rate that was compared with the wavelet-based oximeter respiratory rate derived from the PPG signal. Results: Photoplethysmograms were obtained from 18 children aged 18 mo to 12 y, breathing spontaneously at rates of 17 to 27 breaths per minute. There was close correspondence between the wavelet-based oximeter respiration rate and the manual respiratory rate, with the difference between them being less than one breath per minute in all children. Conclusion: Our automated algorithm allows the accurate determination of respiratory rate from photoplethysmograms of a heterogeneous group of children. We believe that our automated wavelet-based signal-processing techniques could soon be easily incorporated into current pulse oximetry technology. [ABSTRACT FROM AUTHOR]

Background: Wavelet-based methods of analyzing ECG signals have been used to identify specific features in cardiac arrhythmias. Since some of these features are rate dependent, it is a requirement that they are examined across a range of physiological heart rates. The wavelet transform is a signal analysis tool that can elucidate spectral and temporal information simultaneously from complex signals, including the ECG. The aim of this study was to identify the local frequency characteristics of the ECG using a real-time wavelet scalogram and to study the rate dependence of these features.Methods: We examined the spectral temporal behavior of the local characteristics of the electrocardiogram (ECG) of 10 patients, in whom precise control of heart rate was achieved using right atrial pacing. Temporary reprogramming was used to adjust the paced atrial rate to predetermined values so that a rate-controlled rhythm was produced that closely resembled sinus rhythm.Results: Rate-dependent features are seen on time-frequency scalograms. As the rate increases, the temporal spacing of features decrease and the frequency bands shift upward on the plot. Two patients with abnormal atrioventricular conduction demonstrate features of Wenckebach conduction and fusion.Conclusions: Characterization of the rate-dependent features of the ECG in a paced atrial rhythm by wavelet transform techniques has revealed some additional information not readily seen on single lead ECG analysis. This model provides a surrogate for changes that might be expected during rate changes in physiological sinus rhythm. It is envisaged that this method will offer advantages in detecting features of clinical significance that may not be readily seen by existing methods. [ABSTRACT FROM AUTHOR]

Focuses on finding coordinated atrial activity during ventricular fibrillation using wavelet decomposition. Analysis of surface electrocardiogram with a novel signal analysis technique; Unreported structure within the ECG tracing; Evidence linking the structure to unexpected phenomena occurring in the heart.

An integrated method for the prediction of the spatial pollution distribution within a street canyon directly from a microscopic traffic simulation model is outlined. The traffic simulation package Paramics is used to model the flow of vehicles in realistic traffic conditions on a real road network. This produces details of the amount of pollutant produced by each vehicle at any given time. The authors calculate the dispersion of the pollutant using a particle tracking diffusion method which is superimposed on a known velocity and turbulence field. This paper shows how these individual components may be integrated to provide a practical street canyon pollution model. The resulting street canyon pollution model provides isoconcentrations of pollutant within the road topography. [ABSTRACT FROM AUTHOR]

Although teachers today recognize the importance of integrating technology into their curricula, successful implementation often is hampered by both external (first-order) and internal (second-order) barriers. This study was designed to examine the relationship between first- and second-order barriers to technology implementation by observing and interviewing several teachers within a single school who had achieved varying levels of integration. Although first-order barriers constrained all teachers' efforts in this school, teachers responded differently to these constraints based at least in part on their beliefs about what constitutes effective classroom practice. Strategies for technology staff development are discussed. (Keywords: educational change, teachers' beliefs, technology integration.) [ABSTRACT FROM AUTHOR]