54 research outputs found
Ethical blindness, EGMs and public policy : a tentative essay comparing the EGM and tobacco industries
No full textArguing a case by way of analogy can be perilous. Each problem has its own particulars that analogy and examples from other domains often obscure. Therefore it is with some trepidation that this paper discusses similarities and differences between the poker-machine (EGM) and the tobacco industries. The author has no special knowledge of the tobacco industry beyond that of the reasonably informed citizen. Rather it is out of concern about ethics and product safety for EGMs that the paper addresses the following question: what, if any, are the substantive ethical differences between the EGM industry and the tobacco industry
A novel diagnostic tool to identify atrial endo-epicardial asynchrony using signal fingerprinting
No full textObjective: Patients with persistent atrial fibrillation (AF) have more electrical endo-epicardial asynchrony (EEA) during sinus rhythm (SR) than patients without AF. Prior mapping studies indicated that particularly unipolar, endo- and/or epicardial electrogram (EGM) morphology may be indicators of EEA. This study aim to develop a novel method for estimating the degree of EEA by using unipolar EGM characteristics recorded from either the endo- and/or epicardium. Methods: Simultaneous endo-epicardial mapping during sinus rhythm was performed in 86 patients. EGM characteristics, including unipolar voltages, low-voltage areas (LVAs), potential types (single, short/long double and fractionated potentials: SP, SDP, LDP and FP) and fractionation duration (FD) of double potentials (DP) and FP were compared between EEA and non-EEA areas. Asynchrony Fingerprinting Scores (AFS) containing quantified EGM characteristics were constructed to estimate the degree of EEA. Results: Endo- and epicardial sites of EEA areas are characterized by lower unipolar voltages, a higher number of LDPs and FPs and longer DP and FP durations. Patients with AF have lower potential voltages in EEA areas, along with alterations in the potential types. The EE-AFS, containing the proportion of endocardial LVAs and FD of epicardial DPs, had the highest predictive value for determining the degree of EEA (AUC: 0.913). Endo- and epi-AFS separately also showed good predictive values (AUC: 0.901 and 0.830 respectively). Conclusions: EGM characteristics can be used to identify EEA areas. AFS can be utilized as a novel diagnostic tool for accurately estimating the degree of EEA. These characteristics potentially indicate AF related arrhythmogenic substrates.Signal Processing System
Critical appraisal of technologies to assess electrical activity during atrial fibrillation: a position paper from the European Heart Rhythm Association and European Society of Cardiology Working Group on eCardiology in collaboration with the Heart Rhythm Society, Asia Pacific Heart Rhythm Society, Latin American Heart Rhythm Society and Computing in Cardiology
No full textWe aim to provide a critical appraisal of basic concepts underlying signal recording and processing technologies applied for (i) atrial fibrillation (AF) mapping to unravel AF mechanisms and/or identifying target sites for AF therapy and (ii) AF detection, to optimize usage of technologies, stimulate research aimed at closing knowledge gaps, and developing ideal AF recording and processing technologies. Recording and processing techniques for assessment of electrical activity during AF essential for diagnosis and guiding ablative therapy including body surface electrocardiograms (ECG) and endo- or epicardial electrograms (EGM) are evaluated. Discussion of (i) differences in uni-, bi-, and multi-polar (omnipolar/Laplacian) recording modes, (ii) impact of recording technologies on EGM morphology, (iii) global or local mapping using various types of EGM involving signal processing techniques including isochronal-, voltage- fractionation-, dipole density-, and rotor mapping, enabling derivation of parameters like atrial rate, entropy, conduction velocity/direction, (iv) value of epicardial and optical mapping, (v) AF detection by cardiac implantable electronic devices containing various detection algorithms applicable to stored EGMs, (vi) contribution of machine learning (ML) to further improvement of signals processing technologies. Recording and processing of EGM (or ECG) are the cornerstones of (body surface) mapping of AF. Currently available AF recording and processing technologies are mainly restricted to specific applications or have technological limitations. Improvements in AF mapping by obtaining highest fidelity source signals (e.g. catheter-electrode combinations) for signal processing (e.g. filtering, digitization, and noise elimination) is of utmost importance. Novel acquisition instruments (multi-polar catheters combined with improved physical modelling and ML techniques) will enable enhanced and automated interpretation of EGM recordings in the near future.Signal Processing SystemsBiomechanical Engineerin
Parametric optimisation of heat treated recycling aluminium (AA6061) by response surface methodology
No full textAlternating typical primary aluminium production with recycling route should benefit various parties, including the environment since the need of high cost and massive energy consumption will be ruled out. At present, hot extrusion is preferred as the effective solid-state recycling process compared to the typical method of melting the swarf at high temperature. However, the ideal properties of extruded product can only be achieved through a controlled process used to alter the microstructure to impart properties which benefit the working life of a component, which also known as heat treatment process. To that extent, this work ought to investigate the effect of extrusion temperature and ageing time on the hardness of the recycled aluminium chips. By employing Analysis of Variance (ANOVA) for full factorial design with centre point, a total of 11 runs were carried out randomly. Three dissimilar extrusion temperatures were used to obtain gear-shape billet. Extruded billets were cut and ground before entering the treatment phase at three different ageing times. Ageing time was found as the influential factor to affect the material hardness, rather than the extrusion temperature. Sufficient ageing time allows the impurity atoms to interfere the dislocation phenomena and yield great hardness. Yet, the extrusion temperatures still act to assist the bonding activities via interparticle diffusion transport matter.Published versio
Sensor-to-Cell Height Estimation for Conductivity Estimation in Cardiac Cells
No full textThe heart is one of our vital organs. It functions by periodically contracting in a rhythmic way. Sometimes, this rhythmic behaviour is affected by abnormalities in the tissue. These conditions are referred to as cardiac arrhythmias. One kind is of specific interest, called atrial fibrillation (AF). To further study AF, methods have been developed to estimate the conductivity of cardiac cells based on the measured electrical signals. In addition, other parameters of interest besides the conductivity are involved. The goal of this project was to consider one of the parameters in the electrogram (EGM) model: the sensor-to-cell height.First, we studied the effect of the height as a parameter in the model when used for conductivity estimation. To that end, a detector was built with which we can explain the effect of all involved parameters on the ability to accurately estimate any parameters of interest.In addition, we considered the case where the height is unknown and is estimated, thus possibly including estimation errors. The focus was on the consequences of making errors in the estimation of the height with respect to conduction block detection and conductivity estimation.Lastly, the effort was made to estimate the height. Here, the optimisation problem of height estimation was formalised and derived as its implementable form. At first, a simplified EGM model was assumed in order to mimic and estimate cell-specific effects, i.e. the cell conductivities. Then, the height was estimated in various situations to study its behaviour and performance under different conditions. Then, also the standard EGM model was used in the same way, after which we also tested the performance of the designed algorithm in combination with existing conductivity estimation methods.Electrical Engineering | Signals and System
Residues of ochratoxin A in different biological matrices of laying hens orally administrated ochratoxin A, esterified glucomannan and Saccharomyces cerevisiae
No full textRESIDUES OF OCHRATOXIN A IN DIFFERENT BIOLOGICAL MATRICES OF LAYING HENS ORALLY ADMINISTERED OCHRATOXIN A, ESTERIFIED GLUCOMANNAN AND SACCHAROMYCES CEREVISIAE
L. Rizzi1, A. Zaghini2, A. Altafini2, M. Simioli1, P. Roncada2
1Dipartimento di Morfofisiologia Veterinaria e Produzioni Animali
2Dipartimento di Sanità Pubblica Veterinaria e Patologia Animale
Alma Mater Studiorum - Università degli Studi di Bologna - Italy
[email protected] (e-mail of the corresponding author)
The purpose of this study was to evaluate the in vivo ability of an esterified glucomannan (EGM), and of a Saccharomyces cerevisiae (SC) strain (inactivated by autoclave) to reduce the oral absorption of ochratoxin A (OTA) added to a basal diet for laying hens.
Six experimental groups of Isa-Brown laying hens (21 birds/group) were daily administered 6 different diets: basal diet (0-0), diet supplemented with 0.2% EGM (EGM-0), with 0.2% SC (SC-0), with OTA 0.2 ppm (0-OTA), with 0.2% EGM+OTA 0.2 ppm (EGM-OTA), and with 0.2% SC+OTA 0.2 ppm (SC-OTA). After 12 weeks, birds were euthanized by cervical dislocation, and liver, muscle, and blood samples were collected for the determination of OTA levels by HPLC. Data were subjected to analysis of variance and means compared using a Student’s t test. The observed OTA concentrations were low (the range was 2.00-0.31 ppb) and decreasing from liver to plasma. They did not change significantly in the 3 experimental groups administered with OTA. This lack of significant differences may be due to the low doses of OTA added to basal diet
Array Processing in Atrial Fibrillation: Application of different signal models and LAT estimation techniques
No full textAtrial fibrillation (AF) is the most commonly occurring arrhythmia in clinical practice and can have a significant impact on the current and future wellbeing of the patient. By placing an unipolar sensor array directly on the epicardium during an open-heart surgery to measure the electrical activity of the atrium, more insight about this disease can be obtained. One method to obtain these insights is by applying common signal processing models to the measured electrogram (EGM). This thesis further investigates this application and argues why the most common array processing signal models are fundamentally incompatible with this application and proposes two different signal models to rectify the identified discrepancies. The proposed signal models are subsequently analyzed and the conclusion is drawn that both novel signal models better fit the EGM signals, but one signal model in particular shows promising results. This potential is exemplified by using this signal model to formulate a novel LAT estimation technique that can compete with state of the art LAT estimation methods in terms of estimation accuracy and execution time. This result shows the potential of the proposed signal model and opens the door to explore more applications in the future.Electrical Engineering | Signals and System
Characterization of unipolar electrogram morphology:a novel tool for quantifying conduction inhomogeneity
No full textAIMS: Areas of conduction inhomogeneity (CI) during sinus rhythm may facilitate the initiation and perpetuation of atrial fibrillation (AF). Currently, no tool is available to quantify the severity of CI. Our aim is to develop and validate a novel tool using unipolar electrograms (EGMs) only to quantify the severity of CI in the atria. METHODS AND RESULTS: Epicardial mapping of the right atrium (RA) and left atrium, including Bachmann's bundle, was performed in 235 patients undergoing coronary artery bypass grafting surgery. Conduction inhomogeneity was defined as the amount of conduction block. Electrograms were classified as single, short, long double (LDP), and fractionated potentials (FPs), and the fractionation duration of non-single potentials was measured. The proportion of low-voltage areas (LVAs, <1 mV) was calculated. Increased CI was associated with decreased potential voltages and increased LVAs, LDPs, and FPs. The Electrical Fingerprint Score consisting of RA EGM features, including LVAs and LDPs, was most accurate in predicting CI severity. The RA Electrical Fingerprint Score demonstrated the highest correlation with the amount of CI in both atria (r = 0.70, P < 0.001). CONCLUSION: The Electrical Fingerprint Score is a novel tool to quantify the severity of CI using only unipolar EGM characteristics recorded. This tool can be used to stage the degree of conduction abnormalities without constructing spatial activation patterns, potentially enabling early identification of patients at high risk of post-operative AF or selection of the appropriate ablation approach in addition to pulmonary vein isolation at the electrophysiology laboratory.</p
Visualization of users\u27 requirements: Introduction of the Evaluation Grid Method
No full textDuring the last decade, a new type of approaches have emerged in Japanese environmental psychology. These approaches have characteristics that they are aiming to clarify users'requirements for the environment as the design questions to be solved, compared with the traditional approaches aiming to clarify the environment-human relationship to provide actual design solutions. As an example of these new approaches, the Evaluation Grid Method (EGM), a semi-structured interview method developed by the author based on Kelly's Personal Construct Theory is introduced. In the EGM, by asking the reasons of why an environment is more preferable to others recurrently, together with leading questions (laddering), each participant's requirements to the environment are elicited structurally as well as phenomenologically. Also by cumulating each participant's requirements, the extensive structure of the requirements to the environment embraced by people is produced. In this paper, a detailed procedure and the outcome of the EGM are presented on the elicitation of workers' requirements for the office environment. Also recent applied examples where the EGM research was applied as an design aid in architectural as well as industrial field will be introduced
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