3D finite element electrical model of larval zebrafish ECG signals

Assessment of heart function in zebrafish larvae using electrocardiography (ECG) is a potentially useful tool in developing cardiac treatments and the assessment of drug therapies. In order to better understand how a measured ECG waveform is related to the structure of the heart, its position within the larva and the position of the electrodes, a 3D model of a 3 days post fertilisation (dpf) larval zebrafish was developed to simulate cardiac electrical activity and investigate the voltage distribution throughout the body. The geometry consisted of two main components; the zebrafish body was modelled as a homogeneous volume, while the heart was split into five distinct regions (sinoatrial region, atrial wall, atrioventricular band, ventricular wall and heart chambers). Similarly, the electrical model consisted of two parts with the body described by Laplace’s equation and the heart using a bidomain ionic model based upon the Fitzhugh-Nagumo equations. Each region of the heart was differentiated by action potential (AP) parameters and activation wave conduction velocities, which were fitted and scaled based on previously published experimental results. ECG measurements in vivo at different electrode recording positions were then compared to the model results. The model was able to simulate action potentials, wave propagation and all the major features (P wave, R wave, T wave) of the ECG, as well as polarity of the peaks observed at each position. This model was based upon our current understanding of the structure of the normal zebrafish larval heart. Further development would enable us to incorporate features associated with the diseased heart and hence assist in the interpretation of larval zebrafish ECGs in these conditions

Heart Closed-Loop Model for the Assessment of Cardiac Pacing

We developed a closed-loop model of cardiac stimulation using a finite element model of the whole-heart embedded in the torso that is proposed as an useful tool for pacemaker design and testing. The electrical activity of the cardiac tissue is reproduced with a bidomain model incorporated with the FitzHugh-Nagumo equations. The finite element model is developed in Comsol Multiphysics, both in two and in three dimensions and then exported in Simulink environment where the pacemaker algorithm is implemented. To validate the model, we chose a demand inhibited pacemaker, which stimulates the myocardium only if the intrinsic activity of the heart is not revealed, but every type of pacemaker can be simulated. The model generates a controlled spontaneous activation in the sinoatrial node and it is also able to reproduce realistic electrocardiographic signals and the effects that the stimulation has on them

Collaborative filtering with behavioral models

10.1145/3209219.3209235UMAP 2018 - Proceedings of the 26th Conference on User Modeling, Adaptation and Personalization91-9

Comparative electrochemical study of some cobalt(III) and cobalt(II) complexes with azamacrocycles and b-diketonato ligands

The electrochemical properties of eight mixed-ligand cobalt(III) and cobalt(II) complexes of the general formulas [CoIII(Rac)cyclam](ClO4)2 (1)(4) and [Co2II(Rac)tpmc](ClO4)3 (5)(8) were studied. The substances were investigated in aqueous NaClO4 solution and non-aqueous LiClO4/CH3CN solution by cyclic voltammetry at a glassy carbon electrode. In aqueous solution, cyclam and Rac ligands being soluble in water undergo anodic oxidation. Coordination to Co(III) in complexes 14, stabilizes these ligands but reversible peaks in catohodic region indicate the redox reaction CoIII/CoII ion. In the case of the binuclear Co(II) complexes 58, peaks recorded on the CVs represent oxidation of the bridged Rac ligand. The complexes examined influence the cathodic reaction of hydrogen evolution in aqueous solutions by shifting its potential to more negative values and its current is increased. In non-aqueous solution the CVs of the ligands show irreversible anodic peaks for cyclam, tpmc and for the Rac ligands soluble in acetonitrile. The absence of any peaks in the case of the investigated complexes 14 indicates that coordination to Co(III) stabilizes both the cyclam and Rac ligands. Cyclic voltammograms of the complexes 58 show oxidation processes of the Rac ligand and Co(II) ions but the absence of a highly anodic peak of the coordinated macrocycle tpmc shows its stabilization. Contrary to in aqueous solution, the redox reaction Co(III)/Co(II) does not occur in acetonitrate indicating a higher stability of the complexes 14 in this media in comparison with the binuclear cobalt(II)-tpmc complexes 58