Two-Path All-pass Based Half-Band Infinite Impulse Response Decimation Filters and the Effects of Their Non-Linear Phase Response on ECG Signal Acquisition

This paper is based on the novel use of a very high fidelity decimation filter chain for Electrocardiogram (ECG) signal acquisition and data conversion. The multiplier-free and multi-stage structure of the proposed filters lower the power dissipation while minimizing the circuit area which are crucial design constraints to the wireless noninvasive wearable health monitoring products due to the scarce operational resources in their electronic implementation. The decimation ratio of the presented filter is 128, working in tandem with a 1-bit 3rd order Sigma Delta (ΣΔ) modulator which achieves 0.04 dB passband ripples and -74 dB stopband attenuation. The work reported here investigates the non-linear phase effects of the proposed decimation filters on the ECG signal by carrying out a comparative study after phase correction. It concludes that the enhanced phase linearity is not crucial for ECG acquisition and data conversion applications since the signal distortion of the acquired signal, due to phase non-linearity, is insignificant for both original and phase compensated filters. To the best of the authors’ knowledge, being free of signal distortion is essential as this might lead to misdiagnosis as stated in the state of the art. This article demonstrates that with their minimal power consumption and minimal signal distortion features, the proposed decimation filters can effectively be employed in biosignal data processing units.

An analysis of beginning mentors’ critical incidents in English post-compulsory education: navigating stormy waters

This qualitative study explores the barriers and dilemmas faced by beginning and novice mentors in post-compulsory education in the southeast of England. It analyses critical incidents (Tripp, 2012) taken from the everyday practice of mentors who were supporting new teachers and lecturers in the southeast of England. It categorises different types of critical incidents that mentors encountered and describes the strategies and rationales mentors used to support mentees and (indirectly) their learners and colleagues. The study explores ways in which mentors' own values, beliefs and life experiences affected their mentoring practice.  Methodology As part of a specialist master’s-level professional development module, 21 mentors wrote about two critical incidents (Tripp, 2012) taken from their own professional experiences, which aimed to demonstrate their support for their mentee’s range of complex needs. These critical incidents were written up as short case studies, which justified the rationale for their interventions and demonstrated the mentors' own professional development in mentoring. Critical incidents were used as units of analysis and categorised thematically by topic, sector and mentoring strategies used. Findings The research demonstrated the complex nature of decision-making and the potential for professional learning within a mentoring dyad. The study of these critical incidents found that mentors most frequently cited the controversial nature of teaching observations, the mentor’s role in mediating professional relationships, the importance of inculcating professional dispositions in education, and the need to support new teachers so that they can use effective behaviour management strategies. This study contributes to our understanding of the central importance of mentoring for professional growth within teacher education. It identifies common dilemmas that novice mentors face in post-compulsory education, justifies the rationale for their interventions and mentoring strategies, and helps to identify ways in which mentors' professional development needs can be met. It demonstrates that mentoring is complex, non-linear and mediated by mentors’ motivation and values.