scholarly journals Effect of orthodontic brackets and different wires on radiofrequency heating and magnetic field interactions during 3-T MRI

2014 ◽  
Vol 43 (2) ◽  
pp. 20130356 ◽  
Author(s):  
S Görgülü ◽  
S Ayyıldız ◽  
K Kamburoğlu ◽  
S Gökçe ◽  
T Ozen
Keyword(s):  
Magnetic Field ◽  
Orthodontic Brackets ◽  
Radiofrequency Heating

scholarly journals Effect of orthodontic brackets and different wires on radiofrequency heating and magnetic field interactions during 3.0-T MRI: Author response

2016 ◽  
Vol 45 (1) ◽  
pp. 20150314
Author(s):  
Serkan Görgülü ◽  
Simel Ayyıldız ◽  
Kıvanç Kamburoğlu ◽  
Sıla Gökçe ◽  
Tuncer Ozen
Keyword(s):  
Magnetic Field ◽  
Orthodontic Brackets ◽  
Author Response ◽  
Radiofrequency Heating ◽  
3.0 T ◽  
3.0 T Mri

Evaluating the efficiency of radiofrequency heating in tokamaks: the impact of orbital topology and poloidal inhomogeneity

2001 ◽  
Vol 65 (5) ◽  
pp. 407-452 ◽  
Author(s):  
DIRK VAN EESTER
Keyword(s):  
Magnetic Field ◽  
Coarse Graining ◽  
Destructive Interference ◽  
Simplified Models ◽  
Poloidal Magnetic Field ◽  
Diffusion Operator ◽  
Mode Spectrum ◽  
Radiofrequency Heating ◽  
Order Of Magnitude ◽  
The Impact

Radiofrequency heating in toroidal geometry is described. Starting from a general theory, expressions for the dielectric response and the radiofrequency diffusion operator are obtained. The computationally most efficient simplified expressions bear a close resemblance to the results of uniform plasma theory, but differ from them in their interpretation. In cases where the simplified expressions do not describe the physics faithfully, more general but computationally slower ones are available. Rigorously accounting for the geometry and the wave field yields fine structure that is commonly overlooked. Aside from causing the well-known k∥-upshift or downshift impacting on the Doppler shift, the non-zero poloidal magnetic field modifies the orbital topology and forces one to account for the poloidal inhomogeneity of the static magnetic field. The expressions obtained restore intuition on how an electric field interacts with a charged particle, but, in so doing, cast doubt on the degree of realism of predictions of simplified models that do not account for the constructive or destructive interference phenomena introduced by the orbital topology non-uniformity. The expressions represent a numerical challenge, but show the necessity for the detailed description: the ‘coarse-graining’ underlying simplified models yields a result that has the right order of magnitude for interference related to crosstalk between resonances or multiple encounters with a given resonance, but may be an order of magnitude wrong for predictions on the combined effect of a poloidal mode spectrum. A Fokker–Planck code BATCH (Bounce-Averaged Tool for Cyclotron Heating), relying on the expressions obtained, is presented and some results are discussed.

Radiofrequency heating and magnetic field interactions of fixed partial dentures during 3-tesla magnetic resonance imaging

2013 ◽  
Vol 116 (5) ◽  
pp. 640-647 ◽  
Author(s):  
Simel Ayyıldız ◽  
Kıvanç Kamburoğlu ◽  
Cumhur Sipahi ◽  
Sema Murat ◽  
Serkan Görgülü ◽  
...  
Keyword(s):  
Magnetic Resonance Imaging ◽  
Magnetic Field ◽  
Magnetic Resonance ◽  
3 Tesla ◽  
Resonance Imaging ◽  
Radiofrequency Heating

Magnetic-field strengths from optical polarization data

1967 ◽  
Vol 31 ◽  
pp. 381-383
Author(s):  
J. M. Greenberg
Keyword(s):  
Magnetic Field ◽  
Optical Polarization ◽  
Polarization Data ◽  
Term Model ◽  
Source Of Information ◽  
Field Strengths

Van de Hulst (Paper 64, Table 1) has marked optical polarization as a questionable or marginal source of information concerning magnetic field strengths. Rather than arguing about this–I should rate this method asq+-, or quarrelling about the term ‘model-sensitive results’, I wish to stress the historical point that as recently as two years ago there were still some who questioned that optical polarization was definitely due to magnetically-oriented interstellar particles.

Observing the galactic magnetic field

1967 ◽  
Vol 31 ◽  
pp. 375-380
Author(s):  
H. C. van de Hulst
Keyword(s):  
Magnetic Field ◽  
Fair Agreement ◽  
Solar Neighbourhood ◽  
Galactic Magnetic Field ◽  
The Magnetic Field

Various methods of observing the galactic magnetic field are reviewed, and their results summarized. There is fair agreement about the direction of the magnetic field in the solar neighbourhood:l= 50° to 80°; the strength of the field in the disk is of the order of 10-5gauss.

Structure in the radiation of the galactic disk

1967 ◽  
Vol 31 ◽  
pp. 355-356
Author(s):  
R. D. Davies
Keyword(s):  
Magnetic Field ◽  
Galactic Disk ◽  
Galactic Magnetic Field ◽  
Measured Polarization

Observations at various frequencies between 136 and 1400 MHz indicate a considerable amount of structure in the galactic disk. This result appears consistent both with measured polarization percentages and with considerations of the strength of the galactic magnetic field.

Calculated Coronal Magnetic Fields and Their Comparison with the Coronal Structures as Observed during Five Solar Eclipses

1994 ◽  
Vol 144 ◽  
pp. 559-564
Author(s):  
P. Ambrož ◽  
J. Sýkora
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Magnetic Fields ◽  
Solar Corona ◽  
Coronal Magnetic Field ◽  
Coronal Magnetic Fields ◽  
Solar Eclipses ◽  
Coronal Structures

AbstractWe were successful in observing the solar corona during five solar eclipses (1973-1991). For the eclipse days the coronal magnetic field was calculated by extrapolation from the photosphere. Comparison of the observed and calculated coronal structures is carried out and some peculiarities of this comparison, related to the different phases of the solar cycle, are presented.

Faint Hα Emission in the Corona and Its Relation to the Prominences

1994 ◽  
Vol 144 ◽  
pp. 339-342
Author(s):  
V. N. Dermendjiev ◽  
Z. Mouradian ◽  
J.- L. Leroy ◽  
P. Duchlev
Keyword(s):  
Magnetic Field ◽  
Solar Corona ◽  
Essential Role ◽  
Hα Emission

AbstractThe relation between episodically observed in the solar corona faint Hαemission structures and the long lived prominences was studied. Particular consideration was given for cases in which the corresponding prominences had undergone DB process. An MHD interpretation of the phenomenon “emissions froides” (cool emission) is proposed in which an essential role plays the prominence supporting magnetic field.

Evolution of Large-Scale Coronal Structures

1994 ◽  
Vol 144 ◽  
pp. 29-33
Author(s):  
P. Ambrož
Keyword(s):  
Magnetic Field ◽  
Field Line ◽  
Large Scale ◽  
Coronal Magnetic Field ◽  
Source Surface ◽  
Solar Cycles ◽  
Characteristic Relationship ◽  
The Magnetic Field ◽  
Coronal Structures

AbstractThe large-scale coronal structures observed during the sporadically visible solar eclipses were compared with the numerically extrapolated field-line structures of coronal magnetic field. A characteristic relationship between the observed structures of coronal plasma and the magnetic field line configurations was determined. The long-term evolution of large scale coronal structures inferred from photospheric magnetic observations in the course of 11- and 22-year solar cycles is described.Some known parameters, such as the source surface radius, or coronal rotation rate are discussed and actually interpreted. A relation between the large-scale photospheric magnetic field evolution and the coronal structure rearrangement is demonstrated.

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