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Earphones (EP) are a worldwide, massively adopted product, assumed to be innocuous provided the recommendations on sound doses limits are followed. Nevertheless, sound is not the only physical stimulus that derives from EP use, si...
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Earphones (EP) are a worldwide, massively adopted product, assumed to be innocuous provided the recommendations on sound doses limits are followed. Nevertheless, sound is not the only physical stimulus that derives from EP use, since they include a built-in permanent magnet from which a static magnetic field (SMF) originates. We performed 2D maps of the SMF at several distances from 6 models of in-ear EP, showing that they produce an exposure that spans from ca. 20 mT on their surface down to tens of μT in the inner ear. The numerous reports of bioeffects elicited by SMF in that range of intensities (applied both acutely and chronically), together with the fact that there is no scientific consensus over the possible mechanisms of interaction with living tissues, suggest that caution could be recommendable. In addition, more research is warranted on the possible effects of the combination of SMF with extremely low frequency and radiofrequency fields, which has so far been scarcely studied. Overall, while several open questions about bioeffects of SMF remain to be addressed by the scientific community, we find sensible to suggest that the use of air-tube earphones is probably the more conservative, cautious choice.
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Magnetic resonance (MR) imaging relies on a strong static magnetic field in conjunction with careful orchestration of pulsed linear gradient magnetic fields and radiofrequency magnetic fields in order to generate images. The inter...
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Magnetic resonance (MR) imaging relies on a strong static magnetic field in conjunction with careful orchestration of pulsed linear gradient magnetic fields and radiofrequency magnetic fields in order to generate images. The interaction of these fields with patients as well as materials with magnetic or conducting properties can be a source of risk in the MR environment. This article provides a basic review of the physical underpinnings of the primary risks in MR imaging to foster development of intuition with respect to both patient and risk management in the MR environment.
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In this work, the effects of induced field generated by the magnetized wall on the static normal force of magnetorheological fluids have been studied both theoretically and experimentally. Firstly, the magnetic field distributions...
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In this work, the effects of induced field generated by the magnetized wall on the static normal force of magnetorheological fluids have been studied both theoretically and experimentally. Firstly, the magnetic field distributions between two parallel ferromagnetic sheets in a uniform field have been investigated. The magnitude and direction of normal force created by the field gradient in different field regions are calculated based on the Biot-Savart theorem. In an attempt to obtain the correspondences between the magnetization of the magnetized sheets and the magnetic flux density of the field, we designed a uniform magnetic field generator for measuring the induced field of the magnetized sheets. The static normal forces of 30% volume fraction magnetorheological fluids with or without magnetized wall condition have been measured by a commercial plate-plate rheometer, and the field fluctuation at the edge of the magnetized sheet has been validated by controlling the radius of test area. The experimental results indicated that the magnetized sheets with a thickness of 0.2 mm can increase the static normal force by up to 20% when the thickness of suspensions is 0.5 mm. But the increment is limited by the saturation magnetization of material itself, in addition, the non-uniform magnetic field of the magnetized sheets will adversely affect the increase of the static normal force. The experimental results are basically consistent with the theoretical analysis when the radius of test area is 8 mm, but underestimate the field increment for the 10 mm-radius case which may caused by the uneven distribution of particles.
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Magnetic resonance imaging (MRI) is a powerful, non-invasive diagnostic medical imaging technique widely used to acquire detailed information about anatomy and function of different organs in the body, in both health and disease. ...
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Magnetic resonance imaging (MRI) is a powerful, non-invasive diagnostic medical imaging technique widely used to acquire detailed information about anatomy and function of different organs in the body, in both health and disease. It utilizes electromagnetic fields of three different frequency bands: static magnetic field (SMF), time-varying gradient magnetic fields (GMF) in the kHz range and pulsed radiofrequency fields (RF) in the MHz range. There have been some investigations examining the extent of genetic damage following exposure of bacterial and human cells to all three frequency bands of electromagnetic fields, as used during MRI: the rationale for these studies is the well documented evidence of positive correlation between significantly increased genetic damage and carcinogenesis. Overall, the published data were not sufficiently informative and useful because of the small sample size, inappropriate comparison of experimental groups, etc. Besides, when an increased damage was observed in MRI-exposed cells, the fate of such lesions was not further explored from multiple 'down-stream' events. This review provides: (i) information on the basic principles used in MRI technology, (ii) detailed experimental protocols, results and critical comments on the genetic damage investigations thus far conducted using MRI equipment and, (iii) a discussion on several gaps in knowledge in the current scientific literature on MRI. Comprehensive, international, multi-centered collaborative studies, using a common and widely used MRI exposure protocol (cardiac or brain scan) incorporating several genetic/epigenetic damage end-points as well as epidemiological investigations, in large number of individuals/patients are warranted to reduce and perhaps, eliminate uncertainties raised in genetic damage investigations in cells exposed in vitro and in vivo to MRI. (C) 2015 Elsevier B.V. All rights reserved.
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Purpose: A procedure for assessing occupational exposure due to magnetic resonance imaging (MRI) gradient magnetic fields and movement-induced effects in the static magnetic field is proposed and tested. Methods: The procedure was...
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Purpose: A procedure for assessing occupational exposure due to magnetic resonance imaging (MRI) gradient magnetic fields and movement-induced effects in the static magnetic field is proposed and tested. Methods: The procedure was based on the application of the weighted-peak method in time domain. It was tested in two 1.5 T total-body and one 3 T head-only scanner MRI facilities in Rome (Italy). Exposure due to switched gradient fields was evaluated in locations inside the magnet room where operators usually stay during particular medical procedures (e.g., cardiac examinations of anesthetized patients); MRI sequences were selected to approach as far as possible a representative worst case exposure scenario. Movement-induced effects were evaluated considering the actual movements of volunteer operators during work activity, by measuring the perceived time-varying magnetic field by a head-worn probe. The analysis of results was based on ICNIRP 1998 and 2010 guidelines, following a weighted-peak approach and including an ad hoc extension to the latter ones, needed to verify compliance in the frequency range 0-1 Hz. Results: Exposures due to switched gradient fields in 1.5 T MRI scanners mostly resulted noncom-pliant with ICNIRP 1998 occupational reference levels, being, at the same time, always compliant with ICNIRP 2010 ones. Gradient-field levels and ICNIRP indexes were significantly lower for the 3 T unit, due to its small dimensions, as that unit was a head-only scanner. Movement-induced effects resulted potentially noncompliant only in the case the operator moved the head inside the bore of a 1.5 T scanner. Conclusions: The procedure had proven to be a sound approach to exposure assessment in MRI. Its testing allowed to draw some general considerations about exposures to gradient magnetic fields and movement-induced effects.
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Discussed is generation of highly uniform and highly gradient static magnetic fields by magnetic circuits containing permanent magnets. Described are the most frequently used magnetic circuits and formulated their mathematical mod...
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Discussed is generation of highly uniform and highly gradient static magnetic fields by magnetic circuits containing permanent magnets. Described are the most frequently used magnetic circuits and formulated their mathematical models. The crucial point of the paper is represented by solution of several typical examples, discussion of their result and their validation by measurements on a simple experimental stand.
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Previous papers in the literature show no agreement on the effects of static magnetic fields (SMFs) on water supercooling and freezing kinetics. Hypothetical effects of the SMF orientation and the presence of ions in the sample ar...
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Previous papers in the literature show no agreement on the effects of static magnetic fields (SMFs) on water supercooling and freezing kinetics. Hypothetical effects of the SMF orientation and the presence of ions in the sample are also unclear. To shed light on this matter, we froze 10-mL pure water samples and 0.9% NaCl solutions subjected or not to the SMFs generated by two magnets. We found that the relative position of the magnet poles affected the magnetic field orientation, strength, and the spatial magnetic gradients established throughout the sample. Thus, the SMF strength ranged from 107 to 359 mT when unlike magnet poles faced each other whereas it ranged from 0 to 241 mT when like magnet poles were next to each other. At both conditions, we did not detect any effect of the SMFs on the time at which nucleation occurred, the extent of supercooling, and the phase transition and total freezing times in both pure water and 0.9% NaCl solutions. More experiments, under well-characterized SMFs, should be performed to definitively evaluate the ability of SMFs in improving food freezing. (C) 2017 Elsevier Ltd. All rights reserved.
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We investigated the effects of 6- and 10-T static magnetic fields (SMFs) on the expression of protooncogenes using Western blot immunohybridization methods. We used a SMF exposure system, which can expose cells to a spatially inho...
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We investigated the effects of 6- and 10-T static magnetic fields (SMFs) on the expression of protooncogenes using Western blot immunohybridization methods. We used a SMF exposure system, which can expose cells to a spatially inhomogeneous 6 T with a strong magnetic field (MF) gradient (41.7 T/m) and a spatially homogeneous 10 T of the highest magnetic flux density in this experiment. HL-60 cells exposed to either 6- or 10-T SMF for periods of 1 to 48 h did not exhibit remarkable differences in levels of c-Myc and c-Fos protein expression, as compared with sham-exposed cells. In contrast, c-Jun protein expression increased in HL-60 cells after exposure to 6-T SMF for 24, 36, 48, and 72 h. These results suggest that a homogeneous 10-T SMF does not alter the expression of the c-jun, c-fos, and c-myc protooncogenes. However, our observation that exposure to a strong MF gradient induced c-Jun expression suggests that a strong MF gradient may have significant biological effects, particularly regarding processes related to an elevation of c-jun gene expression.
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We assessed postural body sway performance after exposure to movement induced time-varying magnetic fields in the static magnetic stray field in front of a 7 Tesla (T) magnetic resonance imaging scanner. Using a double blind rando...
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We assessed postural body sway performance after exposure to movement induced time-varying magnetic fields in the static magnetic stray field in front of a 7 Tesla (T) magnetic resonance imaging scanner. Using a double blind randomized crossover design, 30 healthy volunteers performed two balance tasks (i.e., standing with eyes closed and feet in parallel and then in tandem position) after standardized head movements in a sham, low exposure (on average 0.24 T static magnetic stray field and 0.49 T·s-1 time-varying magnetic field) and high exposure condition (0.37 T and 0.70 T·s -1). Personal exposure to static magnetic stray fields and time-varying magnetic fields was measured with a personal dosimeter. Postural body sway was expressed in sway path, area, and velocity. Mixed-effects model regression analysis showed that postural body sway in the parallel task was negatively affected (P < 0.05) by exposure on all three measures. The tandem task revealed the same trend, but did not reach statistical significance. Further studies are needed to investigate the possibility of independent or synergetic effects of static magnetic stray field and time-varying magnetic field exposure. In addition, practical safety implications of these findings, e.g., for surgeons and others working near magnetic resonance imaging scanners need to be investigated.
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Recent research demonstrated that exposure of mice to both inhomogeneous (3-477mT) and homogeneous (145mT) static magnetic fields (SMF) generated an analgesic effect toward visceral pain elicited by the intraperitoneal injection o...
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Recent research demonstrated that exposure of mice to both inhomogeneous (3-477mT) and homogeneous (145mT) static magnetic fields (SMF) generated an analgesic effect toward visceral pain elicited by the intraperitoneal injection of 0.6% acetic acid. In the present work, we investigated behavioral responses such as writhing, entry avoidance, and site preference with the help of a specially designed cage that partially protruded into either the homogeneous (ho) or inhomogeneous (inh) SMF. Aversive effects, cognitive recognition of analgesia, and social behavior governed mice in their free locomotion between SMF and sham sides. The inhibition of pain response (I) for the 0-5, 6-20, and 21-30min periods following the challenge was calculated by the formula I=100 (1-x/y) in %, where x and y represent the number of writhings in the SMF and sham sides, respectively. In accordance with previous measurements, an analgesic effect was induced in exposed mice (Iho=64%, P<0.0002 and Iinh=62%, P<0.002). No significant difference was found in the site preference (SMFho, inh vs. sham) indicating that SMF is neither aversive nor favorable. Comparison of writhings observed in the sham versus SMF side of the cage revealed that SMF exposure resulted in significantly fewer writhings than sham (Iho=64%, P<0.004 and Iinh=81%, P<0.03). Deeper statistical analysis clarified that the lateral SMF gradient between SMF and sham sides could be responsible for most of the analgesic effect (Iho=91%, P<0.02 and Iinh=54%, P<0.02).
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