Envelope frequency following responses are stronger for high-pass than low-pass filtered vowels

Background: To assess hearing in response to speech, the envelope frequency following response (FFR) can be observed at the fundamental frequency of a vowel stimulus, and its harmonics. FFRs are complex non-linear phenomena, which require better understanding for allowing robust inferences on the assessment of hearing and hearing aid fitting. Objectives: To evaluate the effect of stimulus bandwidth on FFR detection rates using filtered vowel stimuli with equal sound levels. Design: FFRs were collected whilst presenting repeated vowels (in consonant-vowel-consonant format) filtered into different bandwidths. Eighty stimuli per word were presented at 70 dB SPL LAeq through insert earphones with an inter-stimulus interval of 1s. Responses were detected using frequency-domain Hotelling’s T2 (HT2) tests for individual multiples of the fundamental frequency (F0) and for combinations of F0 multiples. Study Sample: Eleven native English-speaking subjects with normal hearing thresholds. Results: Average detection rates are highest (69%) with stimuli high-pass filtered >1000 Hz, and significantly lower for low-pass filtered stimuli (40%). Conclusion: High-pass filtered vowels elicit stronger FFRs than low-pass filtered vowels at the same dB SPL LAeq. For testing hearing using band-limited speech, filtering effects (due to hearing loss, hearing aid setting or stimulus choice) on responses must be considered

Integrated fan cooling of the lower back for wheelchair users

Introduction: A large proportion of a wheelchair user's body is in contact with their wheelchair. Integrated fan cooling systems fitted to a wheelchair's backrest aim to alleviate the build-up of heat at the skin-chair interface. The aim of this pilot study was to evaluate the effectiveness of an integrated fan cooling system at cooling the user during daily pushing activity. Methods: Eight male able-bodied participants completed two conditions, with (FAN) and without (CON) fan cooling, pushing for four 15 min blocks. The fan was turned on (highest setting) at the end of block 1 (FAN), whilst in CON the fan remained off. Skin temperature was measured over the back and chest throughout alongside heart rate and perceptual responses (rating of perceived exertion, thermal sensation, thermal comfort, wetness sensation) at the end of each 15 min block. Results: Wetness sensation and lower back skin temperature were lower in FAN (both p < 0.02), with the difference in lower back skin temperature between the two conditions being 2.20°C at the end of block 4. Conclusion: The integrated fan cooling system provided significant cooling to the lower back without affecting any other physiological or perceptual response, besides wetness sensation

QT analysis of intrauterine growth retarded and normal children at 10 years old

The main objective of the work described in this paper is to develop an algorithm to detect QT, other ECG intervals and to find any correlation between QT, ST, QRS, Heart rate (HR) of normal and IUGR children at 10 yrs. The cohort under study is described in chapter 2 as 41 IUGR and 34 as normal. The ECGs of 24 hour for each child were used to find any differences between the two groups. Normal children have QRS intervals during awake (73.96 ±13.65 ms) and asleep (78.75±14.76 ms), and IUGR has (73.94 ±12.85 ms day, 75.98±14.80 ms night), and IUGR children have a slightly higher corrected QTc (418.25±28.92ms Day, 437.22±20.17 ms night), compared to normal (411.37 ±36.13 ms day, 431.79±20.12 ms night). At 10 years of age the measured ECG intervals of all normal and IUGR children was unable to show any deviation from the normal paediatric limits. IUGR children are relatively more prone to longer QTc intervals

Fetal movement counting using optical fibre sensors

Daily fetal movement counting based on maternal perception is widely deployed to monitor fetal wellbeing. However, the counting performed by the mother is prone to errors for various reasons. There are limited devices on the market that can provide reliable and automatic counting. This paper presents a prototype of a novel fetal movement monitoring device based on fibre Bragg grating sensors. Deformation of the skin caused by a fetal movement can lead to a change of the strain and stress on the optical fibre sensors, therefore can induce distortions to the breathing pattern of the mother. In the study data was gathered by the sensors through strain measurement and was post-processed using Independent Component Analysis and high-pass filtering to show the instances of the fetal movements. Information gathered during user trials with the prototype suggests that the system detects significantly higher numbers of fetus movements than that observed based on the mother's perception. Among the various techniques available for fetal movement monitoring, fibre optic sensing provides many advantages including; multiplex capability, flexibility and minimal size, making the concept an attractive solution for reliable monitoring of antenatal fetal movements

Thriving through trials and tribulations: the impact of the ‘Grand Challenge’ on engineering student resilience skills

Resilience is considered of significant importance for student attainment and work-readiness. This study investigated the impact of Grand Challenge (GC) – an industry-based learning assessment for 1st and 2nd year Engineering students – on student resilience. Resilience scores and psychological distress were measured before and after the GC through questionnaires presented to students. Focus groups were conducted to assess GC’s effect on student resilience qualitatively. Resilience scores in the questionnaires decreased slightly after GC, possibly due to less students completing the post-GC questionnaire. Interestingly, when discussing GC in the focus groups, students did feel GC helped them develop their resilience and understood the impact of resilience on their future career. Overall, the findings help establish GC as a challenge-based learning (CBL) intervention and the extent to which such CBL assessments may affect student resilience skills. The study provides the groundwork for future resilience training and assessment in higher engineering education through CBL events

Visualizing intracardiac atrial fibrillation electrograms using spectral analysis

Atrial fibrillation is the most common cardiac arrhythmia, and it is associated with increased risk of stroke, heart failure, and mortality. This work describes spectral analysis techniques that are being used in conjunction with visualization algorithms to help guide catheter ablation procedures that aim at treating patients with arrhythmia

Patient-specific three-dimensional torso models for analysing cardiac activity

Standard electrocardiogram (ECG) is routinely used for recording cardiac electrical activity but lacks 3D details. Body surface potential mapping techniques have been developed more recently. A major challenge related to this technique is the projection of body signals back to their original sources in the heart. For an accurate projection, one needs to take into account patient-specific electrophysiological data of tissues surrounding the heart. Much information regarding physiological variations, as well as the exact position of organs in the torso, can be obtained from magnetic resonance (MR) images. Here, a patient-specific methodology for building 3D torso models from transverse MR images is proposed. Torso contour detection is based on edge detection using a canny filter and indicating contour points with a polar coordinate system. Organ detection is performed using an interpolation technique with Active Contour modelling. Results show that accurate torso models can be constructed with short processing time

Analysis of spatial variability for the development of reduced lead body surface maps

The spatial frequency of measurement points from standard ECG systems lacks accuracy to diagnose local variability in cardiac activity on the torso. Body Surface Mapping (BSM) improves this accuracy, but lacks the simplicity to be implemented in clinic on a regular basis. Reduced-lead BSM system improves applicability, but currently no standardization of lead reduction has been agreed upon. This research investigates the reduction of BSMs based on Lomb-Scargle Spectral Analysis to determine an appropriate electrode positioning through spatial frequency assessment. Based on the measurement of 13 healthy volunteers, a 128 electrode system could be reduced to a 36 electrode system and an 84 electrode system for ventricular and atrial activity measurements, respectively, with up to 10% loss of the full information provided by the original body surface potential map. Further research will investigate the appropriate positions of these electrodes and the effect of lead reduction for various cardiac abnormalities

A platform to guide catheter ablation of persistent atrial fibrillation using dominant frequency mapping

Dominant frequency (DF) mapping has been widely used to study the pathophysiology of atrial fibrillation (AF). In this study, a DF mapping system was developed to guide catheter ablation on electro-physiology (EP) procedures of persistent AF patients. The proposed platform has an automated graphical user interface (GUI) that processes non-contact unipolar electrograms (EGMs) recorded simultaneously by St. Jude Ensite Velocity System and provides 3D representation of the left atrium with DF behaviours and phase analysis

Spatiotemporal behaviour of high dominant frequency during persistent atrial fibrillation

Atrial electrograms (EGMs) with high dominant frequency (DF) are believed to represent atrial substrates with periodic activation responsible for the maintenance of persistent atrial fibrillation (persAF). This study aimed to assess the DF spatiotemporal behavior using high density noncontact mapping in persAF. For 8 patients undergoing left atrial (LA) persAF ablation, 2048 noncontact virtual unipolar EGMs were simultaneously collected and after the removal of ventricular far-field activity, Fourier based spectral analysis was used to identify DF on each EGM. Atrial areas with the highest DF (HDF, DF ± 0.25 Hz) were delimited in each frame for all EGMs, creating HDF `clouds'. Cumulative HDF clouds found at each frame were counted in the 3-D LA representation. To further assess the temporal stability of the cloud, the number of EGMs not hosting any HDF was determined for each window over time. The results show the number of occurrences of HDF clouds in the LA. The temporal behavior was analyzed by counting the number of positions on the 3-D representation of the LA not visited by HDF along time. Our results show HDF in persAF is not temporally stable and spatial distribution throughout the atria suggests the existence of driver regions with very rapid and regular activity maintaining AF. Therefore mapping the cumulative HDF might be an interesting strategy for ablation