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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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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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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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Recently, the International EMF Project of the World Health Organization (WHO) published an Environmental Health Criteria monograph on static electric and magnetic fields. In the present paper a short overview is given of the biol...
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Recently, the International EMF Project of the World Health Organization (WHO) published an Environmental Health Criteria monograph on static electric and magnetic fields. In the present paper a short overview is given of the biological and health effects discussed in this document. The main conclusions are that no acute effects other than transient phenomena such as vertigo and nausea have been observed with exposure to static magnetic flux densities up to 8 T. There are no reports of long term or chronic adverse effects following prolonged static magnetic field exposure, but few data are available on which to base any judgment. The guidelines on static field exposure recommended by ICNIRP in 1994 are discussed in the light of current scientific knowledge.
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A formulation of the relation between static magnetic induction and Reynolds number in liquid, for vertical Bridgman and LPE growth processes of semiconductors in axial static magnetic field was derived based on a scaling analysis...
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A formulation of the relation between static magnetic induction and Reynolds number in liquid, for vertical Bridgman and LPE growth processes of semiconductors in axial static magnetic field was derived based on a scaling analysis, and the validity of the estimation was experimentally investigated. The calculated values of the effective segregation coefficients for Ga-doped Ge and Pb_(1-x)Sn_xTe crystals grown by the Bridgman method agreed well with the experimentally measured ones from 0 to 6 T of the magnetic induction. In the case of LPE growth on GaP(111)B, nearly diffusion-controlled condition in the liquid was achieved at 6 T. It was shown by in situ observation using a near-infrared (NIR) microscopic interferometer that the static magnetic field reduced the LPE growth rate, and as a result, suppressed appearance of macro-steps and hillocks.
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This paper presents an analytical solution for the magnetic field between two poles of an axially oriented ring magnet. The method involves expanding the scalar potential between the two poles into McLauren series. The magnetic fi...
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This paper presents an analytical solution for the magnetic field between two poles of an axially oriented ring magnet. The method involves expanding the scalar potential between the two poles into McLauren series. The magnetic field is then linked to the field along the axis of the ring. The resulted solution shows the relationship between the geometry of the ring and magnetic field. From this solution, a geometrical relationship can be found to generate near uniform field at the center region of the ring. We also present a geometrical relationship of the ring to generate a peak field at the center. The results are then compared with boundary element analysis (BEA).
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Recently, we have predicted, solely on the basis of symmetry arguments, the existence of strong magnetochiral anisotropy in the displacement current in chiral dielectrics and reported its experimental observation in chiral ferroel...
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Recently, we have predicted, solely on the basis of symmetry arguments, the existence of strong magnetochiral anisotropy in the displacement current in chiral dielectrics and reported its experimental observation in chiral ferroelectrics near their ferroelectric-paraelectric phase transitions [Nat. Commun. 13, 3564 (2022).]. Here, we present a microscopic model that describes both direct and inverse dielectric magnetochiral anisotropy (dMChA) in the chiral ferroelectric triglycine sulfate (TGS), based on the specifics of the charge movement in a time -varying electric field. We predict a strong inverse dMChA in TGS that should be within reach of experimental observation and we find good agreement between our model and the experimental observation of the direct dMChA in TGS.
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The ReA3 reaccelerator facility at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), East Lansing, MI, USA, provides unique access to high-quality beams of a wide variety of isotopes for sc...
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The ReA3 reaccelerator facility at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), East Lansing, MI, USA, provides unique access to high-quality beams of a wide variety of isotopes for scientific research. The high-energy beam transport (HEBT) line from the ReA3 superconducting linear accelerator to the three experimental end stations consists of several iron-dominated normal-conducting quadrupole magnets, dipole magnets, and also combined-function horizontal and vertical corrector magnets. This article focuses on the design and fabrication of a new type of normal-conducting quadrupole magnet with cylindrical split yoke structure and standard quadrupole coils. Electromagnetic simulation results demonstrate that the magnet design fulfills the performance requirements for the ReA3 HEBT beamline. We present the coil fabrication and mechanical assembly details of the magnet. Our analysis results show that the hydraulic requirements for the coils are met.
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Part of the winding near its middle is often omitted when the volume about the centre of a solenoid over which the magnetic field is relatively uniform is to be extended. Field distributions are considered, and optimum gap lengths...
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Part of the winding near its middle is often omitted when the volume about the centre of a solenoid over which the magnetic field is relatively uniform is to be extended. Field distributions are considered, and optimum gap lengths computed. The volume of specified field uniformity is compared with hat of uniform solenoids. The use of solenoids with a gap makes certain precautions essential.
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The article describes a measurement system for magnetic field scanning using a CNC plotter. Comprehensive studies have been conducted on various materials, confirming the effectiveness and precision of the system in analysing the ...
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The article describes a measurement system for magnetic field scanning using a CNC plotter. Comprehensive studies have been conducted on various materials, confirming the effectiveness and precision of the system in analysing the uniformity distribution of the magnetic field.
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