FIR Filter Design using Raised Semi-ellipse Window Function

In this paper, a new two-parameter window function - Raised semi-ellipse (RSE) is proposed. The window is obtained from a fixed elliptical window known as Semi-ellipse window by raising the radius of the minor axis by the parameter (β), and applied for the design of finite impulse response (FIR) digital filters. The spectral parameters of the proposed window are determined first and compared with the Kaiser window – a 2-parameter adjustable window. Subsequently, in its application in filter design with an established design algorithm, the newly proposed adjustable window is compared to the Semi-ellipse window to examine its improvement and also the Kaiser window to compare its performance with a commonly used adjustable window. The filter simulation results show that the filters designed with the proposed window can provide more reduced ripples than the Kaiser window for prescribed spectral characteristics

Stroke prevalence amongst sickle cell disease patients in Nigeria: a multi-centre study

Background: Stroke is a life-changing, debilitating complication of sickle cell disease (SCD). Previous studies had recorded high stroke prevalence amongst this group of patients. Nigeria has a large population of people affected by this condition and this study aims to assess the stroke prevalence in this large population.Methodology: Stroke prevalence data from 14 physicians working in 11 tertiary health centres across the country was collated by doctors using the sickle cell registers and patient case notes. This data was then collated and used to obtain the overall stroke prevalence in adult and children.Results: The stroke prevalence in sickle cell disease patients in Nigeria was observed to be 12.4 per 1000 patients. Prevalence in the adult patients was 17.7 per 1000 patients and 7.4 per 1000 patients in children. Twenty three percent of the affected patients had more than stroke episode.Conclusion: The stroke prevalence in Nigeria is lower than previously recorded rates and further studies will be required to investigate other factors which may play a role.Keywords: sickle cell, stroke, Nigeria, prevalenc