scholarly journals HOLOGRAPHIC EXPERIMENTS ON DEFECTS

2010 ◽  
Vol 25 (23) ◽  
pp. 4397-4473 ◽  
Author(s):  
MATTHIAS C. WAPLER
Keyword(s):  
Magnetic Field ◽  
Heat Bath ◽  
Hydrodynamic Behavior ◽  
Unusual Behavior ◽  
Net Charge ◽  
High Frequencies ◽  
Background Magnetic Field ◽  
Collisionless Regime ◽  
The Magnetic Field ◽  
Matter Fields

Using the AdS/CFT correspondence, we study the anisotropic charge transport properties of both supersymmetric and nonsupersymmetric matter fields on (2+1)-dimensional defects coupled to a (3+1)-dimensional [Formula: see text] "heat bath." We focus on the cases of a finite external background magnetic field, finite net charge density and finite mass and their combinations. In this context, we also discuss the limitations due to operator mixing that appears in a few situations and that we ignore in our analysis. At high frequencies, we discover a spectrum of quasiparticle resonances due to the magnetic field and finite density and at small frequencies, we perform a Drude-like expansion around the DC limit. Both of these regimes display many generic features and some features that we attribute to strong coupling, such as a minimum DC conductivity and an unusual behavior of the "cyclotron" and plasmon frequencies, which become related to the resonances found in the conformal case in an earlier paper. We further study the hydrodynamic regime and the relaxation properties, from which the system displays a set of different possible transitions to the collisionless regime. The mass dependence can be cast in two regimes: a generic relativistic behavior dominated by the UV and a nonlinear hydrodynamic behavior dominated by the IR. In the massless case, we furthermore extend earlier results from the literature to find an interesting selfduality under a transformation of the conductivity and the exchange of density and magnetic field.

On the existence of compressional MHD oscillations in an inhomogeneous magnetoplasma

1990 ◽  
Vol 44 (2) ◽  
pp. 361-375 ◽  
Author(s):  
Andrew N. Wright
Keyword(s):  
Magnetic Field ◽  
Wave Equation ◽  
Density Distribution ◽  
Cold Plasma ◽  
Wave Equations ◽  
Perturbation Field ◽  
Plasma Density Distribution ◽  
Background Magnetic Field ◽  
Transverse Fields ◽  
The Magnetic Field

In a cold plasma the wave equation for solely compressional magnetic field perturbations appears to decouple in any surface orthogonal to the background magnetic field. However, the compressional fields in any two of these surfaces are related to each other by the condition that the perturbation field b be divergence-free. Hence the wave equations in these surfaces are not truly decoupled from one another. If the two solutions happen to be ‘matched’ (i.e. V.b = 0) then the medium may execute a solely compressional oscillation. If the two solutions are unmatched then transverse fields must evolve. We consider two classes of compressional solutions and derive a set of criteria for when the medium will be able to support pure compressional field oscillations. These criteria relate to the geometry of the magnetic field and the plasma density distribution. We present the conditions in such a manner that it is easy to see if a given magnetoplasma is able to executive either of the compressional solutions we investigate.

scholarly journals ANALYSIS OF HIGH-FREQUENCY C-CORE MAGNETIC FLUX LEAKAGES FOR BONE TUMOR WITH INDUCTION HEATING BY USING MULTI-COIL

2019 ◽  
Author(s):  
Metharak Jokpudsa ◽  
Supawat Kotchapradit ◽  
Chanchai Thongsopa ◽  
Thanaset Thosdeekoraphat
Keyword(s):  
Magnetic Field ◽  
High Frequency ◽  
Tumor Tissue ◽  
Low Frequency ◽  
Heat Energy ◽  
High Frequencies ◽  
Frequency Magnetic Field ◽  
High Frequency Magnetic Field ◽  
The Magnetic Field ◽  
Flux Leakage

High-frequency magnetic field has been developed pervasively. The induction of heat from the magnetic field can help to treat tumor tissue to a certain extent. Normally, treatment by the low-frequency magnetic field needed to be combined with magnetic substances. To assist in the induction of magnetic fields and reduce flux leakage. However, there are studies that have found that high frequencies can cause heat to tumor tissue. In this paper present, a new magnetic application will focus on the analysis of the high-frequency magnetic nickel core with multi-coil. In order to focus the heat energy using a high-frequency magnetic field into the tumor tissue. The magnetic coil was excited by 915 MHz signal and the combination of tissues used are muscle, bone, and tumor. The magnetic power on the heating predicted by the analytical model, the power loss density (2.98e-6 w/m3) was analyzed using the CST microwave studio.

scholarly journals Ephemeral states in protein folding under force captured with a magnetic tweezers design

2019 ◽  
Vol 116 (16) ◽  
pp. 7873-7878 ◽  
Author(s):  
Rafael Tapia-Rojo ◽  
Edward C. Eckels ◽  
Julio M. Fernández
Keyword(s):  
Magnetic Field ◽  
Molten Globule ◽  
Magnetic Tweezers ◽  
Protein L ◽  
High Frequencies ◽  
Electric Signals ◽  
Very High Frequencies ◽  
The Magnetic Field ◽  
Very High ◽  
Unique Capability

Magnetic tape heads are ubiquitously used to read and record on magnetic tapes in technologies as diverse as old VHS tapes, modern hard-drive disks, or magnetic bands on credit cards. Their design highlights the ability to convert electric signals into fluctuations of the magnetic field at very high frequencies, which is essential for the high-density storage demanded nowadays. Here, we twist this conventional use of tape heads to implement one in a magnetic tweezers design, which offers the unique capability of changing the force with a bandwidth of ∼10 kHz. We calibrate our instrument by developing an analytical expression that predicts the magnetic force acting on a superparamagnetic bead based on the Karlqvist approximation of the magnetic field created by a tape head. This theory is validated by measuring the force dependence of protein L unfolding/folding step sizes and the folding properties of the R3 talin domain. We demonstrate the potential of our instrument by carrying out millisecond-long quenches to capture the formation of the ephemeral molten globule state in protein L, which has never been observed before. Our instrument provides the capability of interrogating individual molecules under fast-changing forces with a control and resolution below a fraction of a piconewton, opening a range of force spectroscopy protocols to study protein dynamics under force.

scholarly journals Photospheric magnetic structure of coronal holes

2019 ◽  
Vol 629 ◽  
pp. A22 ◽  
Author(s):  
Stefan J. Hofmeister ◽  
Dominik Utz ◽  
Stephan G. Heinemann ◽  
Astrid Veronig ◽  
Manuela Temmer
Keyword(s):  
Magnetic Field ◽  
Magnetic Flux ◽  
Coronal Hole ◽  
Magnetic Structure ◽  
Coronal Holes ◽  
Line Of Sight ◽  
Magnetic Elements ◽  
Background Magnetic Field ◽  
The Individual ◽  
The Magnetic Field

In this study, we investigate in detail the photospheric magnetic structure of 98 coronal holes using line-of-sight magnetograms of SDO/HMI, and for a subset of 42 coronal holes using HINODE/SOT G-band filtergrams. We divided the magnetic field maps into magnetic elements and quiet coronal hole regions by applying a threshold at ±25 G. We find that the number of magnetic bright points in magnetic elements is well correlated with the area of the magnetic elements (cc = 0.83 ± 0.01). Further, the magnetic flux of the individual magnetic elements inside coronal holes is related to their area by a power law with an exponent of 1.261 ± 0.004 (cc = 0.984 ± 0.001). Relating the magnetic elements to the overall structure of coronal holes, we find that on average (69 ± 8)% of the overall unbalanced magnetic flux of the coronal holes arises from long-lived magnetic elements with lifetimes > 40 h. About (22 ± 4)% of the unbalanced magnetic flux arises from a very weak background magnetic field in the quiet coronal hole regions with a mean magnetic field density of about 0.2−1.2 G. This background magnetic field is correlated to the flux of the magnetic elements with lifetimes of > 40 h (cc = 0.88 ± 0.02). The remaining flux arises from magnetic elements with lifetimes < 40 h. By relating the properties of the magnetic elements to the overall properties of the coronal holes, we find that the unbalanced magnetic flux of the coronal holes is completely determined by the total area that the long-lived magnetic elements cover (cc = 0.994 ± 0.001).

Magnetosonic solitons in space plasmas: dark or bright solitons?

2007 ◽  
Vol 73 (6) ◽  
pp. 981-992 ◽  
Author(s):  
O. A. POKHOTELOV ◽  
O.G. ONISHCHENKO ◽  
M. A. BALIKHIN ◽  
L. STENFLO ◽  
P. K. SHUKLA
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Velocity Distribution Function ◽  
Mhd Equations ◽  
Space Plasmas ◽  
Ion Distribution ◽  
Loss Cone ◽  
Solitary Solution ◽  
Background Magnetic Field ◽  
The Magnetic Field

AbstractThe nonlinear theory of large-amplitude magnetosonic (MS) waves in highβ space plasmas is revisited. It is shown that solitary waves can exist in the form of ‘bright’ or ‘dark’ solitons in which the magnetic field is increased or decreased relative to the background magnetic field. This depends on the shape of the equilibrium ion distribution function. The basic parameter that controls the nonlinear structure is the wave dispersion, which can be either positive or negative. A general dispersion relation for MS waves propagating perpendicularly to the external magnetic field in a plasma with an arbitrary velocity distribution function is derived.It takes into account general plasma equilibria, such as the Dory–Guest–Harris (DGH) or Kennel–Ashour-Abdalla (KA) loss-cone equilibria, as well as distributions with a power-law velocity dependence that can be modelled by κdistributions. It is shown that in a bi-Maxwellian plasma the dispersion is negative, i.e. the phase velocity decreases with an increase of the wavenumber. This means that the solitary solution in this case has the form of a ‘bright’ soliton with the magnetic field increased. On the contrary, in some non-Maxwellian plasmas, such as those with ring-type ion distributions or DGH plasmas, the solitary solution may have the form of a magnetic hole. The results of similar investigations based on nonlinear Hall–MHD equations are reviewed. The relevance of our theoretical results to existing satellite wave observations is outlined.

Cassini observations of magnetic holes in the solar wind and Saturn magnetosheath

2020 ◽  
Author(s):  
Tomas Karlsson ◽  
Lina Hadid ◽  
Michiko Morooka ◽  
Jan-Erik Wahlund
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
High Time Resolution ◽  
Magnetic Field Direction ◽  
Scale Size ◽  
Background Magnetic Field ◽  
Cycle Dependence ◽  
The Magnetic Field

&lt;p&gt;We present the first Cassini observations of magnetic holes on the near-Saturn solar wind and magnetosheath, based on data from the MAG magnetometer. We conclude that magnetic holes (defined as isolated decreases of at least 50% compared to the background magnetic field strength) are common in both regions. We present statistical properties of the magnetic holes, including scale size, depth of the magnetic field reduction, orientation, change in magnetic field direction over the holes, and solar cycle dependence. For magnetosheath magnetic holes, also high-time resolution density measurements from the LP Langmuir probe are available, allowing us to study the anti-correlation of density and magnetic field strength in the magnetic holes. We compare to recent results from MESSENGER observations from Mercury orbit, and finally discuss the possible importance of magnetic holes in solar wind-magnetosphere interaction at Saturn.&lt;/p&gt;

scholarly journals The Solar Orbiter magnetometer

2020 ◽  
Vol 642 ◽  
pp. A9 ◽  
Author(s):  
T. S. Horbury ◽  
H. O’Brien ◽  
I. Carrasco Blazquez ◽  
M. Bendyk ◽  
P. Brown ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Thermal Environment ◽  
Instrument Design ◽  
Performance Data ◽  
Significant Development ◽  
Mission Duration ◽  
Background Magnetic Field ◽  
Mechanical Sensor ◽  
The Magnetic Field ◽  
Orbiter Mission

The magnetometer instrument on the Solar Orbiter mission is designed to measure the magnetic field local to the spacecraft continuously for the entire mission duration. The need to characterise not only the background magnetic field but also its variations on scales from far above to well below the proton gyroscale result in challenging requirements on stability, precision, and noise, as well as magnetic and operational limitations on both the spacecraft and other instruments. The challenging vibration and thermal environment has led to significant development of the mechanical sensor design. The overall instrument design, performance, data products, and operational strategy are described.

scholarly journals HALL EFFECT STUDIES OF THE SUPERCONDUCTING FERROMAGNET UCoGe

2017 ◽  
Vol 35 (2) ◽  
Author(s):  
Danica Krstovska ◽  
Eden Steven ◽  
Andhika Kiswandhi ◽  
James S. Brooks
Keyword(s):  
Magnetic Field ◽  
Hall Effect ◽  
Anomalous Hall Effect ◽  
Simple Relation ◽  
Hall Resistance ◽  
Unusual Behavior ◽  
Perpendicular Component ◽  
Induced Changes ◽  
The Magnetic Field ◽  
Characteristic Field

We find that the Hall effect in a single crystal of UCoGe varies as a function of the angle  between the applied magnetic field and the easy magnetic axis up to fields of 18 T at 0.2 K, i.e. in the region where both superconductivity and ferromagnetic order coexist. Instead of following the conventional cos dependence the two components that com-prise the total Hall resistance, the anomalous and ordinary Hall effect, exhibit quite an unusual behavior with the field direction. The anomalous Hall effect is found to be determined by the parallel component of the magnetization. We sug-gest that the field induced changes in magnetization due to the field rotation play an important role in the observed unu-sual behavior. The ordinary Hall effect cannot be described by the simple relation to the perpendicular component of the magnetic field implying that this component of the Hall effect may be also affected by the variations in magnetization at the characteristic field (kink field). A field induced moment polarization is also observed in Hall effect as in magnetore-sistance, which advances previous findings in UCoGe. The Hall effect slope reverses sign at the kink field indicative of small but possible Fermi surface reconstruction around this field. Our findings show that in UCoGe multiple mecha-nisms contribute to the observed field induced moment polarization at the kink field.

Hydrodynamic Behavior of Magnetic Nanocomposite Spheres Under Magnetic Fields

2011 ◽  
Author(s):  
H. L. Wamocha ◽  
R. Asmatulu ◽  
T. S. Ravigururajan
Keyword(s):  
Magnetic Field ◽  
Study Drug ◽  
Magnetic Nanocomposite ◽  
Test Results ◽  
Hydrodynamic Behavior ◽  
Oil Emulsion ◽  
Pump Speed ◽  
In Vivo Tests ◽  
The Magnetic Field

In the present study, drug carrying magnetic nanocomposite spheres were fabricated using oil-in-oil emulsion/solvent evaporation method and characterized via different techniques. The spheres with a diameter of 200 nm and 3 μm consist of poly (lactic-co-glycolic acid) (PLGA), a drug and magnetic nanoparticles (e.g., Fe3O4 or Co0.5Zn0.5Fe2O4). The spheres were initially dispersed in both deionized (DI) water and viscous glycerol solutions, and pumped in a magnetic field at different tube diameters, pump speeds and concentrations to study the hydrodynamic behavior of drug-carrying magnetic nanocomposite spheres. The test results showed that the magnetic field, tube diameter, pump speed and magnetic nanoparticle concentrations in the spheres drastically changed the capturing efficiency of the spheres. In the in vivo tests of the spheres, these parameters should be considered in order to increase the efficiency of the drug delivery systems.

scholarly journals Unusual magnetoelectric effect in paramagnetic rare-earth langasite

2020 ◽  
Vol 5 (1) ◽  
Author(s):  
Lukas Weymann ◽  
Lorenz Bergen ◽  
Thomas Kain ◽  
Anna Pimenov ◽  
Alexey Shuvaev ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Rare Earth ◽  
Electric Field ◽  
Field Vector ◽  
Electric Polarization ◽  
Rare Earth Ions ◽  
Spontaneous Breaking ◽  
Unusual Behavior ◽  
Propagation Of Light ◽  
The Magnetic Field

Abstract Violation of time reversal and spatial inversion symmetries has profound consequences for elementary particles and cosmology. Spontaneous breaking of these symmetries at phase transitions gives rise to unconventional physical phenomena in condensed matter systems, such as ferroelectricity induced by magnetic spirals, electromagnons, non-reciprocal propagation of light and spin waves, and the linear magnetoelectric (ME) effect—the electric polarization proportional to the applied magnetic field and the magnetization induced by the electric field. Here, we report the experimental study of the holmium-doped langasite, HoxLa3−xGa5SiO14, showing a puzzling combination of linear and highly non-linear ME responses in the disordered paramagnetic state: its electric polarization grows linearly with the magnetic field but oscillates many times upon rotation of the magnetic field vector. We propose a simple phenomenological Hamiltonian describing this unusual behavior and derive it microscopically using the coupling of magnetic multipoles of the rare-earth ions to the electric field.

Sign in / Sign up

Export Citation Format

Share Document