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Compliance with the established exposure limits for the electric field (E-field) induced in the human brain due to low-frequency magnetic field (B-field) induction is demonstrated by numerical dosimetry. The objective of this study is to investigate the dependency of dosimetric compliance assessments on the applied methodology and segmentations. The dependency of the discretization uncertainty (i.e., staircasing and field singularity) on the spatially averaged peak E-field values is first determined using canonical and anatomical models. Because spatial averaging with a grid size of 0.5 mm or smaller sufficiently reduces the impact of artifacts regardless of tissue size, it is a superior approach to other proposed methods such as the 99th percentile or smearing of conductivity contrast. Through a canonical model, it is demonstrated that under the same uniform B-field exposure condition, the peak spatially averaged E-fields in a heterogeneous model can be significantly underestimated by a homogeneous model. The frequency scaling technique is found to introduce substantial error if the relative change in tissue conductivity is significant in the investigated frequency range. Lastly, the peak induced E-fields in the brain tissues of five high-resolution anatomically realistic models exposed to a uniform B-field at ICNIRP and IEEE reference levels in the frequency range of 10 Hz to 100 kHz show that the reference levels are not always compliant with the basic restrictions. Based on the results of this study, a revision is recommended for the guidelines/standards to achieve technically sound exposure limits that can be applied without ambiguity.

In this paper, open issues pertaining to the modeling of skin, i.e., a potential target tissue for peripheral nerve stimulation due to low-frequency magnetic field exposure, are addressed. First, an equivalent conductivity for a single-layer skin model is derived using a multi-layer skin structure. Unlike previous works, where the conductivity of the stratum corneum or of a weighted average between several skin layers were employed, the conductivity value of the dermis is found to conservatively estimate the peak electric field induced in the stratum basale (i.e., where Merkel nerve endings start to emerge). Then, the induced fields inside a high-resolution anatomical model using the proposed skin conductivity are compared with the basic restrictions provided by the existing guidelines and safety standards. The analysis of the obtained results shows that the relationship between the basic restrictions and the reference or maximum permissible exposure levels recommended by these safety standards is not always consistent.

A Wireless Power Transfer (WPT) system based on magnetic resonant coupling is applied to a small electrical Unmanned Aerial Vehicle (UAV) to recharge its battery. The transmitting coil is assumed to be on a terrestrial base station, while the receiving coil is onboard. The operation frequency is fixed to 150 kHz. Key aspects for this kind of application are the reduction of the weight of the onboard WPT system while maintaining high WPT efficiency and avoiding EMC/EMI problems on the drone electronic system. In this study, the feasibility of the WPT charging system applied to a demonstrative drone has been proved

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Background: Atrial fibrillation (AF) ablation outcome is still operator dependent. Ablation Index (AI) is a new lesion quality marker that has been demonstrated to allow acute durable pulmonary vein (PV) isolation followed by a high single-procedure arrhythmia-free survival.This prospective, multicenter study was designed to evaluate the reproducibility of acute PV isolation guided by the AI.Methods: A total of 490 consecutive patients with paroxysmal (80.4%) and persistent AF underwent first time PV encircling and were divided in four study groups according to operator preference in choosing the ablation catheter (a contact force [ST] or contact force surround flow [STSF] catheter) and the AI setting (330 at posterior and 450 at anterior wall or 380 at posterior and 500 at anterior wall). Radiofrequency was delivered targeting interlesion distance ≤6 mm. Results:The rate of first-pass PV isolation (ST330 90 ± 16%, ST380 87 ± 19%, STSF330 90 ± 17%, STSF380 91 ± 15%, P = .585) was similar among the four study groups, whereas procedure (ST330 129 ± 44 minutes, ST380 144 ± 44 minutes, STSF330 120 ± 72 minutes, STSF380 125 ± 73 minutes, P < .001) and fluoroscopy time (ST330 542 ± 285 seconds, ST380 540 ± 416 seconds, STSF330 257 ± 356 seconds, STSF380 379 ± 454 seconds, P < 0.001) significantly differed. The difference in the rate of first-pass isolation was not statistical different (P = .06) among the 12 operators that performed at least 15 procedures. Conclusions:An ablation protocol respecting strict criteria for contiguity and quality lesion results in high and comparable rate of acute PV isolation among operator performing ablation with different catheters, AI settings, procedure, and fluoroscopy times. K E Y W O R D S ablation index, atrial fibrillation, catheter ablation, reproducibility 874

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