Magnetic interference from a tramway in electrocardiogram signals

ECG is a method used in diagnostics and monitoring of the heart. The ECG measures the electrical activity between two or more predetermined positions on the body surface. These ECG signals might be disturbed by surrounding magnetic _elds, which might induce an interference into the signals. A tram passing by an ECG equipment has the possibility to induce interference into the ECG signals, due to changing currents on the tram line. In this study experimental and real life measurements have been made to analyse whether or not a tram track passing by Sk_ane University Hospital, Lund, would interfere destructively with ECG signals Experiments were made to simulate an accelerating/decelerating tram, contact loss between pantograph and overhead caternary and AC ripple of the DC current powering the tram network. Experimental simulations were made representing the magnetic _eld of these interfering sources at distances 10 meters and 25 meters, respectively. The real life measurements were made in Goteborg at Slottsparken, where the equipment was placed at an approximate distance of 10meters and 25meters from the tram track, respectively. All measurements were made with both a monitor and an oscilloscope since the monitor has a filter that removes some of the signals which were to be investigated. Measurement showed that AC Ripple of the DC current interfere with ECG signals. In the case of ripple the interference is larger measured with an oscilloscope than the monitor. The ripple due to a 6 pulse recti_cation showed quite large interference. For a 12 pulse recti_cation the interference was reduced considerably. At a distance of 10 meters the ripple interference was large, though the interference was greatly reduced at a distance of 25 meters. In Göteborg a 6 pulse recti_cation of the current is used and quite large interference could be seen correlate with passing trams at a distance of 10 meters, though not all passing trams showed any disturbance in the ECG signals. For measurements at 25 meters no noticeable interference could be seen correlate with passing trams. Acceleration and deceleration showed no interference for any measurements. Contact loss between pantograph and overhead caternary showed only an interference in the experimental simulations without _lter. No cases of contact loss could be seen when measuring in Goteborg and therefore no measurements for this in a real life setup could be recorded. A passing tram will induce interfering disturbances into ECG signals. Whether if the interference will be of a problem in interpretation of ECG signals is a question that experienced physicians has to answe

Effect of Apex Locator and Electronic Pulp Tester on Pacemaker Function: An In Vitro study

This study evaluated the potential for interference of electronic pulp tester, electronic apex locators and diathermy with pacemaker function. Dental Instruments used. Apex locators: 1. Root ZX (J Morita Corp., Japan), 2. Propex (Dentsply Maillefer, Ballaigues, Switzerland), 3. Mini Apex locator (SybronEndo, Anaheim, CA, USA). Pulp tester: 1. Parkell pulp vitality tester (Farmingdale, NY, USA). Diathermy: 1. Neomed 250 B Pacing system used: 1. Medtronic (KVDD901. The study design consisted of directly connecting the pacemaker lead, EAL, and oscilloscope across a 150-ohm resistor. With the electronic apex locator/ electronic pulp tester/diathermy operating on a flat bench top, the telemetry wand was held directly over the pacemaker to monitor the pacing pattern for a period of 30 s. A negative control was conducted with the pacemaker alone. Pacemaker activity was continuously recorded on the EGM printout of the telemetric programmer. These recordings were then examined for pacer inhibition, noise reversion or inappropriate pacemaker pulses. CONCLUSION: From the results of the present study, it may be concluded, 1. The tested Electronic Apex Locators Root ZX (J Morita Corp., Japan), Propex (Dentsply Maillefer, Ballaigues, Switzerland), Sybron Endo mini (SybronEndo, Anaheim, CA, USA) do not interfere with cardiac pacemaker function. 2. The tested Electric pulp tester, Parkell pulp vitality tester (Farmingdale, NY, USA) does not interfere with cardiac pacemaker function. 3. The results show that the use of Diathermy (Neomed 250 B) interfered with the normal pacing, leading to complete inhibition of the pacing system. Manufacturers of EALs continue to warn against the use of their devices in patients with cardiac pacemakers despite the absence of evidence to support such claims. Although they may possess bench test data similar to those shown above, the lack of clinical data would make it difficult to obtain FDA approval for the devices without such warnings. Human trials are needed to clarify this issue

Near field shielding of a wireless power transfer (WPT) current coil

The configuration of an infinite planar conductive shield is examined when it is excited by an electromagnetic near field generated by a coil current source as that of a wireless power transfer (WPT) system. The analytical expressions of the electromagnetic field based on the transmission theory of shielding are given for different frequencies and different incidence angles of the near field generated by the coil current, assuming the conductive planar shield placed in the close proximity of the coil. The obtained results are discussed and compared with other traditional analytical and numerical solutions

Assessment of Electromagnetic Fields at NASA Langley Research Center

This report presents the results of an assessment of ElectroMagnetic Fields (EMF) completed at NASA Langley Research Center as part of the Langley Aerospace Research Summer Scholars Program. This project was performed to determine levels of electromagnetic fields, determine the significance of the levels present, and determine a plan to reduce electromagnetic field exposure, if necessary. This report also describes the properties of electromagnetic fields and their interaction with humans. The results of three major occupational epidemiological studies is presented to determine risks posed to humans by EMF exposure. The data for this report came from peer-reviewed journal articles and government publications pertaining to the health effects of electromagnetic fields

Possible Exposure of Persons with Cardiac Pacemakers to Extremely Low Frequency (ELF) Electric and Magnetic Fields

The number of persons with implanted cardiac pacemakers (PM) has increased in Western countries. The aim of this paper is to investigate the possible situations where persons with a PM may be exposed to extremely low frequency (ELF) electric (EF) and magnetic fields (MF) that may disturb their PM. Based on our earlier studies, it is possible to find such high public exposure to EFs only in some places near 400 kV power lines, where an EF may disturb a PM in unipolar mode. Such EFs cannot be found near 110 kV power lines. Disturbing MFs can be found near welding machines. However, we do not have measurement data from welding. Based on literature and earlier studies at Tampere University of Technology, it is difficult to find public EF or MF exposure that is high enough to interfere with PMs

Planar immersion lens with metasurfaces

The solid immersion lens is a powerful optical tool that allows light entering material from air or vacuum to focus to a spot much smaller than the free-space wavelength. Conventionally, however, they rely on semispherical topographies and are non-planar and bulky, which limits their integration in many applications. Recently, there has been considerable interest in using planar structures, referred to as metasurfaces, to construct flat optical components for manipulating light in unusual ways. Here, we propose and demonstrate the concept of a planar immersion lens based on metasurfaces. The resulting planar device, when placed near an interface between air and dielectric material, can focus electromagnetic radiation incident from air to a spot in material smaller than the free-space wavelength. As an experimental demonstration, we fabricate an ultrathin and flexible microwave lens and further show that it achieves wireless energy transfer in material mimicking biological tissue

Electromagnetic interference of GSM mobile phones with the implantable deep brain stimulator, ITREL-III

BACKGROUND: The purpose was to investigate mobile phone interference with implantable deep brain stimulators by means of 10 different 900 Mega Hertz (MHz) and 10 different 1800 MHz GSM (Global System for Mobile Communications) mobile phones. METHODS: All tests were performed in vitro using a phantom especially developed for testing with deep brain stimulators. The phantom was filled with liquid phantom materials simulating brain and muscle tissue. All examinations were carried out inside an anechoic chamber on two implants of the same type of deep brain stimulator: ITREL-III from Medtronic Inc., USA. RESULTS: Despite a maximum transmitted peak power of mobile phones of 1 Watt (W) at 1800 MHz and 2 W at 900 MHz respectively, no influence on the ITREL-III was found. Neither the shape of the pulse form changed nor did single pulses fail. Tests with increased transmitted power using CW signals and broadband dipoles have shown that inhibition of the ITREL-III occurs at frequency dependent power levels which are below the emissions of GSM mobile phones. The ITREL-III is essentially more sensitive at 1800 MHz than at 900 MHz. Particularly the frequency range around 1500 MHz shows a very low interference threshold. CONCLUSION: These investigations do not indicate a direct risk for ITREL-III patients using the tested GSM phones. Based on the interference levels found with CW signals, which are below the mobile phone emissions, we recommend similar precautions as for patients with cardiac pacemakers: 1. The phone should be used at the ear at the opposite side of the implant and 2. The patient should avoid carrying the phone close to the implant

Creating and probing long-range order in atomic clouds

Ultracold atoms interacting with the optical modes of a high-Q optical ring cavity can synchronize their motion. The collective behavior makes the system interesting for quantum computing applications. This paper is devoted to the study of the collective coupling. We report on the first observation of a collective dynamics and on the realization of a laser, the gain mechanism of which is based on collective atomic recoil. We show that, if the atoms are subject to a friction force, starting from an unordered distribution they spontaneously form a moving density grating. Furthermore, we demonstrate that a 1D atomic density grating can be probed via Bragg scattering. By heterodyning the Bragg-reflected light with a reference beam, we obtain detailed information on phase shifts induced by the Bragg scattering process

Modeling EMI Resulting from a Signal Via Transition Through Power/Ground Layers

Signal transitioning through layers on vias are very common in multi-layer printed circuit board (PCB) design. For a signal via transitioning through the internal power and ground planes, the return current must switch from one reference plane to another reference plane. The discontinuity of the return current at the via excites the power and ground planes, and results in noise on the power bus that can lead to signal integrity, as well as EMI problems. Numerical methods, such as the finite-difference time-domain (FDTD), Moment of Methods (MoM), and partial element equivalent circuit (PEEC) method, were employed herein to study this problem. The modeled results are supported by measurements. In addition, a common EMI mitigation approach of adding a decoupling capacitor was investigated with the FDTD method