Large Magnetic Field Research Articles

Penatalaksanaan Pemeriksaan MRI Cervical Pada Kasus Syringomyelia Pada Medulla Spinalis Di Rumah Sakit Primaya Tangerang

Management of Cervical MRI Examination in Cases of Syringomyelia in the Spinal Medulla at Primaya Hospital Tangerang. Magnetic Resonance Imaging (MRI) is a state-of-the-art diagnostic tool for examining and detecting the body using a large magnetic field and radio frequency waves, without the use of X-rays or radioactive materials, which produces cross-sectional images of the human body/organs using a magnetic field. strength between 0.064 – 1.5 tesla (1 tesla = 1000 Gauss) and vibrational resonance of the hydrogen atom nucleus. MRI can produce images of the vertebral column, spinal cord, and also the CSF. The MRI screening procedure is ideal for the differential diagnosis of structural disorders that can affect the spinal roots and spinal cord. This examination is used in carrying out a vertebral examination at once, namely scanning starting directly from the cervical vertebrae and also up to the sacrum. So this examination can directly diagnose the cervical, thoracic, lumbar, sacral vertebrae and also includes the coccyx. The purpose of this study was to determine the management of cervical MRI examination with clinical syringomyelia. This research is descriptive qualitative with a case study approach. The subject is a patient with clinical syringomyelia. All subjects underwent Cervical MRI examination at 1.5 tesla to find out the sequence and procedure and sequence information used. From the research results obtained according to the theory using T1-weighted imaging with administration of contrast agent. While in the field using the cervical MRI protocol without contrast, it is sufficient to establish a diagnosis using an examination procedure with a localizer sequence design, sagittal T1, Axial T1 FSE, Axial T2, Axial 2D marge, sagittal T2 fat sat, Axial T2 thoracic 2-3, myelo 2D. The T2 fat sat sagittal sequence section makes it possible to see the anatomy, namely syringomyelia.

Calculation of dipole matrix elements for the modeling of H-[formula omitted] Stark broadening in the presence of large magnetic field

B-spline basis sets are applied to the calculation of dipole matrix elements for the hydrogen atom placed in an intense magnetic field, in view of applications to the spectroscopic analysis of white dwarf atmospheres. A focus is put on the H-α line and magnetic field values in the kilotesla range are considered. The dipole matrix elements are shown to be significantly sensitive to the magnetic field. In the framework of plasma diagnostic, this means that the Stark broadening of the line, which is involved in density measurements, can be misinterpreted if the atomic structure is not well accounted for in numerical codes. As an illustration, we consider the H-ασ− component and apply a computer simulation method to the modeling of the Stark broadening of this line. The calculated dipole matrix elements are used therein as input.

Highly Anisotropic Even-Denominator Fractional Quantum Hall State in an Orbitally Coupled Half-Filled Landau Level.

The even-denominator fractional quantum Hall states (FQHSs) in half-filled Landau levels are generally believed to host non-Abelian quasiparticles and be of potential use in topological quantum computing. Of particular interest is the competition and interplay between the even-denominator FQHSs and other ground states, such as anisotropic phases and composite fermion Fermi seas. Here, we report the observation of an even-denominator fractional quantum Hall state with highly anisotropic in-plane transport coefficients at Landau level filling factor ν=3/2. We observe this state in an ultra-high-quality GaAs two-dimensional hole system when a large in-plane magnetic field is applied. By increasing the in-plane field, we observe a sharp transition from an isotropic composite fermion Fermi sea to an anisotropic even-denominator FQHS. Our data and calculations suggest that a unique feature of two-dimensional holes, namely the coupling between heavy-hole and light-hole states, combines different orbital components in the wave function of one Landau level, and leads to the emergence of a highly anisotropic even-denominator fractional quantum Hall state. Our results demonstrate that the GaAs two-dimensional hole system is a unique platform for the exploration of exotic, many-body ground states.

A High Performance Insulated REBCO Pancake With Conductive Cooling Capability

REBCO Coated Conductors have high tensile strength along their length. They are however sensitive to delamination when traction force is applied on the tape surface, which in a pancake winding corresponds to radial tensile stress. For this reason, most REBCO magnets are dry-wound (not impregnated). One of the drawbacks of dry winding is that conduction cooling to low temperature (below 20 K) would be inefficient. Edge impregnation structures were developed to mitigate this problem but retaining a soft non-stick insulating layer in between the turn. In this paper, we propose an improved pancake structure with the benefits of edge-impregnation but using Hastelloy tape with thin insulation coating to reinforce the winding. The mechanical behavior of such structure is first estimated then validated with high current tests under large background magnetic field. The insulation performance is then tested by rapid ramping and fast discharge.

Exotic quantum states in multilayer phosphorene nanoribbons in electric and magnetic fields

Using the tight-binding method, we modeled the energy spectra of multilayer phosphorene nanoribbons in a perpendicular electric field and in-plane magnetic field. Phosphorene nanosheets have a highly anisotropic honeycomb-like lattice. Their band gap is wider than that of their bulk counterparts, and armchair and zigzag edges of either skewed or regular type terminate the nanowire edges. Zigzag and various skewed edges support states whose wave functions decay exponentially from an edge. These states are virtually dispersionless and split the band gap. In principle, regular armchair edges do not host edge states. Thus, the energy spectrum in this case has a wide band gap. Here, we consider nanoribbons composed of multilayer phosphorene with regular armchair edges. A wide direct energy band gap exists when external fields are absent, but its width decreases when a perpendicular electric field is applied. The Dirac-like cones cross-section emerges at the zone center for a particular field value, named the lowest critical field. Although spin–orbit coupling was not included in the model, there is a small gap at the anticrossing site. The local density of states shows that the conduction- and valence-band states near the anticrossing are localized on the top and bottom surfaces of the nanoribbon. A thorough analysis of the interlayer coupling integrals indicates that for sufficiently thin phosphorene slabs, the electron and hole states at the opposite sides of the slab couple mutually strongly, despite the tendency of an external electric field to separate them. A further increase in the electric field induces an inversion between the conduction and valence band states in the zone center, which is inherent to topological insulators. However, sharp anticrossings at the zone center emerged for certain higher field values, named higher critical fields. Furthermore, when an in-plane magnetic field is applied, the conduction and valence band states shift, causing the dispersion to twist around the center of the k-space. Therefore, the band gap is indirect and closes for a sufficiently large magnetic field. A similar effect is observed in quantum spin Hall insulators, in which an in-plane magnetic field induces a semiconductor-to-semimetal transition. We conclude that the band inversion and topological-like features induced by external fields can be attributed to the strong interlayer coupling inherent to multilayered materials with anisotropic honeycomb lattices.

Study of Crystal Structure and Magnetics Properties in the Normal State of Electron-Doped Eu<sub>2-</sub><i><sub>x</sub></i>Ce<i><sub>x</sub></i>Cu<sub>0.97</sub>Zn<sub>0.03</sub>O<sub>4+</sub><i><sub>α-δ</sub></i> in Overdoped Regime

The normal state of high-Tc superconducting cuprates is crucial to understanding of the mechanism in superconductivity. There are two main ways to remove superconductivity so that the sample is in a normal state, that is by applying a large magnetic field or adding impurities such as Zn to the sample. To investigate the crystal structure and magnetic properties in the normal state of electron-doped high-Tc cuprates in overdoped regime, Eu2-xCexCu0.97Zn0.03O4+α-δ (ECCZO) with x = 0.16, 0.17, 0.18, and 0.19 has been synthesized by the solid-state reaction method. The crystal structure and magnetic properties of the samples were characterized by XRD and SQUID measurements. The results of XRD measurements shows all samples have T’-structure and the values of lattice parameters a, CuO bond length, and crystallite size increased with increasing x. On other hand, the value of lattice parameters c decreased with increasing x, causing the expansion of the tetragonal unit cell in the horizontal direction. From susceptibility measurements, in the normal state with 3% of Zn impurity all samples have the paramagnetic behaviour. The magnetic parameters of these samples analysed by the Curie law. With increasing of Ce concentration, the C and the are increased. The increase in the magnetic parameters since the increasing in magnetic ordering.

Deep‐Subwavelength Resonant Meta‐Optics Enabled by Ultra‐High Index Topological Insulators

AbstractIn nanophotonics, small mode volumes, high‐quality factor resonances, and large field enhancements without metals fundamentally scale with the refractive index and are key for many implementations involving light‐matter interactions. Topological insulators (TIs) are a class of insulating materials that host topologically protected surface states, some of which exhibit extraordinarily high permittivity values. Here, the optical properties of TI bismuth telluride (Bi2Te3) single crystals are studied. It is found that both the bulk and surface states contribute to the extremely large optical constants, with the real part of the refractive index peaking at n ≈ 11. Utilizing these ultra‐high index values, it is demonstrated that Bi2Te3 metasurfaces are capable of squeezing light in deep‐subwavelength structures, with the fundamental magnetic dipole (MD) resonance confined in unit cell sizes smaller than λ/10. It is further shown that dense ultrathin metasurface arrays can simultaneously provide large magnetic and electric field enhancements arising from the high index of the bulk and the surface metallic states. These findings demonstrate the potential of chalcogenide TIs as a platform leveraging the unique combination of ultra‐high‐index dielectric response with surface metallic states for metamaterial design and nanophotonic applications in sensing, non‐linear generation, and quantum information.

Magneto-mechanical stimulation modulates osteocyte fate via the ECM-integrin-CSK axis and wnt pathway

Osteocytes are the mechano-sensors of bones. Large gradient high-static magnetic fields (LG-HMFs) produce stable, high-precision, and non-attenuation mechanical forces. We discovered that magnetic forces opposite to gravity inhibited MLO-Y4 osteocyte proliferation and viability by inducing structural damage and apoptosis. In contrast, magnetic force loading in the same direction as that of gravity promoted the proliferation and inhibited apoptosis of MLO-Y4 osteocytes. Differentially expressed gene (DEG) analysis after magnetic force stimulation indicated that the ECM-integrin-CSK axis responded most significantly to mechanical signals. Wisp2 was the most significant DEG between the 12T upward and downward groups, showing the highest correlation with the Wnt pathway according to the STRING protein interaction database. Explaining the cellular and molecular mechanisms by which mechanical stimuli influence bone remodeling is currently the focus of osteocyte-related research. Our findings provide insights into the effects of LG-HMFs on bone cells, which have further implications in clinical practice.

Magneto-thermopower in MoSe2 monolayer

We study the influence of the external magnetic field, temperature, and electron concentration on the magneto-thermopower due to the phonon-drag effect, Sxxg, in the MoSe2 monolayer. The analytical expression for Sxxg is found from Π-method. Our numerical results show that the density of state and Sxxg show an oscillation as a function of a magnetic field with its amplitude increases in the large magnetic field region. The Sxxg increases with temperatures but decreases with electron concentrations. The numerical calculations for Sxxg are compared with those in the graphene monolayer.

Ground magnetic survey on Mars from the Zhurong rover

AbstractMars’ magnetic field has been measured at large scale by orbiting spacecraft and at very small scale via Martian meteorites. Here we report on a ground magnetic survey on metre to kilometre scales. The Zhurong rover made vector measurements at 16 sites along a 1,089 m track in the Utopia Basin on Mars. It recorded an extremely weak magnetic field, with an order of the average intensity less than that inferred from orbit, in contrast to the large magnetic field in Elysium Planitia measured by InSight. A spacecraft measurement samples an area with radius comparable to its altitude, while a ground measurement samples an area with radius comparable to the depth of the magnetized body. The weak magnetic field measured by Zhurong indicates no magnetization anomalies for a depth of many kilometres around and below the rover’s traverse. We suggest two possible explanations for the weak magnetic field: the entire Utopia Basin may have remained unmagnetized since its formation about 4 billion years ago or that the 5-km-radius ghost crater where Zhurong landed may have been been demagnetized by impact.

Ising superconductivity: A first-principles perspective

The recent discovery of Ising superconductivity has garnered much interest due in part to the resilience of these superconductors to large in-plane magnetic fields. In this Perspective, we explain the basic concepts that define the behavior of Ising superconductors, provide an overview of the electronic structure and magnetic properties with a focus on NbSe2, summarize key experimental observations that have been made in this class of superconductors, highlight the role that defects and proximity-induced effects at interfaces have on Ising superconductivity, and finally discuss the prospects for observing Ising superconductivity in bulk materials.

Thermal properties of the core of magnetar

During very early age of neutron stars, the core cools down faster compared to the crust creating a large thermal gradient in the interior of the star. During 10−100 years, a cooling wave propagates from the core to the crust causing the interior of the star to thermalize. During this duration thermal properties of the core material is of great importance to understand the dynamics of the interior of the star. The heat capacity and thermal conductivity of the core depends on the behaviour of matter inside the core. We investigate these two properties in case of magnetars. Due to presence of large magnetic field, the proton superconductivity is quenched partially inside the magnetars depending upon the comparative values of upper critical field and the strength of the magnetic field present. This produces non-uniformity in the behaviour of matter throughout the star. Moreover, such non-uniformity arises from the variation of nature of the pairing and values of the pairing gap energy. We find that the heat capacity is substantially reduced due to the presence of superfluidity. On the other hand, the thermal conductivity of neutron is enhanced due to proton superconductivity and gets reduced due to neutron superfluidity. Hence, the variation of the thermal properties due to superfluidity in presence of magnetic field is different at different radius inside the star. However, in all the cases the maximum variation is of the order one. This affects the thermal relaxation time of the star and eventually its the thermal evolution.

The Importance of the Pressure Anisotropy Induced by Strong Magnetic Fields on Neutron Star Physics

In this paper we discuss in some detail how the pressures determined from semi-classical statistical averaging of the energy momentum tensor in the presence of a uniform background magnetic field are anisotropic with different pressures arising along and perpendicular to the magnetic field direction. Hence, we analyze how this result can affect two important characteristics of dense magnetized systems: (i) The hadron-quark phase transition in the presence of a magnetic field, (ii) The behavior of the speed of sound in dense magnetized systems. Taking into account that large magnetic fields are expected to be present in the interior of neutron stars, we will stress the role the pressure anisotropy plays in the physics of these compact astronomical objects.

Particle-in-cell simulations of collisionless perpendicular shocks driven at a laser-plasma device

Experiments of generation of quasi-perpendicular collisionless shocks driven by laser plasma were performed at the Shenguang-II laser facility with intense lasers. Here, using a 1D particle-in-cell simulation code including protons, carbon ions, and electrons, we investigate the experimental shock formation via the interaction between the laser-ablated piston and ambient plasma magnetized by a large pre-existing magnetic field and the associated ion dynamics in more detail. Simulation results show that, given enough time and space, ambient protons and carbon ions can be reflected at the piston–ambient interface successively, which leads to the formation of corresponding shocks before the piston and interface. Electric fields associated with the initial interaction known as Larmor coupling and the shocks may accelerate ambient protons, carbon ions reflected at the interface or shocks, and piston ones transmitted to the ambient region before shock formation.

Interhemispheric Asymmetry Due To IMF By Within the Cusp Spherical Elementary Currents

AbstractObservations of interhemispheric asymmetry in the cusp region due to the interplanetary magnetic field (IMF) By component have been performed for years, but those observations typically are not simultaneous in both hemispheres and represent an average picture. Simultaneous instantaneous observations in both hemispheres are rare. We have combined four sets of magnetometers in Antarctica to produce equivalent ionospheric currents and current amplitudes at 10 s resolution using the spherical elementary current systems technique. These Antarctica spherical elementary currents are roughly conjugate to the northern hemisphere spherical elementary currents derived over Greenland and North America. We examined five intervals with large interplanetary magnetic field By positive and negative and demonstrate that the equivalent current pattern in opposite hemispheres are asymmetric with respect to one another during IMF By positive with the cusp throat opening towards the dusk in the northern hemisphere and towards the dawn in the southern hemisphere. This configuration reverses for interplanetary magnetic field By negative. In one of these events we examine the rotation of the equivalent currents in real time in the northern hemisphere. We also compare these results with virtual magnetometer predictions from the Space Weather Modeling Framework. Simultaneous spherical elementary currents observations in both hemispheres are important because they allow us to observe the evolution of the cusp throat during changing solar wind and interplanetary magnetic field conditions.

Effects of strong fringing magnetic fields on turbulent thermal convection

We study the influence of fringing magnetic fields on turbulent thermal convection in a horizontally extended rectangular domain. The magnetic field is created in the gap between two semi-infinite planar magnetic poles, with the convection layer located near the edge of the gap. We employ direct numerical simulations in this set-up for fixed Rayleigh and small Prandtl numbers, but vary the fringe width by controlling the gap between the magnetic poles and the convection cell. The magnetic field generated by the magnets is strong enough to cease the flow in the high magnetic flux region of the convection cell. We observe that as the local vertical magnetic field strength increases, the large-scale structures become thinner and align themselves perpendicular to the longitudinal sidewalls. We determine the local Nusselt and Reynolds numbers as functions of the local Hartmann number (based on the vertical component of the magnetic field), and estimate the global heat and momentum transport. We show that the global heat transport decreases with increasing fringe width for strong magnetic fields but increases with increasing fringe width for weak magnetic fields. In the regions of large vertical magnetic fields, the convective motion becomes confined to the vicinity of the sidewalls. The amplitudes of these wall modes show a non-monotonic dependence on the fringe width.

Occurrence and Evolution of Switchbacks in the Inner Heliosphere: Parker Solar Probe Observations

Since its launch in 2018, the Parker Solar Probe (PSP) mission revealed the presence of numerous fascinating phenomena occurring closer to the Sun, such as the presence of ubiquitous switchbacks (SBs). The SBs are large magnetic field deflections of the local magnetic field relative to a background field. We investigated the statistical properties of the SBs during the first 10 encounters between 13.28 and 58 solar radii (R ⊙) using data from the SWEAP and FIELDS suites on board PSP. We find that the occurrence percentage of small deflections with respect to the Parker spiral decreases with radial distance (R). In contrast, the occurrence percentage of the large deflections (SBs) increases with R, as does the SB patches. We also find that the occurrence of SBs correlates with the bulk velocity of the solar wind, i.e., the higher the solar wind velocity, the higher the SB occurrence. For V sw ≤ 400 km s−1, the SB occurrence percentage shows a constantly increasing trend between 13 and 58 R ⊙. However, for V sw > 400 km s−1, the occurrence percentage saturates beyond 35 R ⊙. The occurrence percentage of mini SB patches (<60 s) shows a decreasing trend with R, while the occurrence percentage of long-duration SB patches (>200 s) increases with R. Sub-Alfvénic regions that we analyzed during Encounters 8–10 have not shown any SBs. This analysis of the PSP data hints that some of the SBs are decaying and some are being created in situ.

Primordial magnetic field generation via primordial black hole disks

Large scale primordial magnetic fields (PMFs) threading the intergalactic medium are observed ubiquitously in the Universe playing a key role in the cosmic evolution. Their origin is still debated constituting a very active field of research. In the present article, we propose a novel natural ab initio mechanism for the origin of such PMFs through the portal of supermassive primordial black holes (PBHs) forming between the Big Bang Nucleosynthesis and the recombination era. In particular, by considering PBHs furnished with a locally isothermal disk we study the generation of a Biermann battery induced seed magnetic field (MF) due to the vortexlike motion of the primordial plasma around the black hole. Finally, by considering monochromatic PBH mass distributions and deriving the relevant MF power spectrum we make a conservative estimate for the seed PMF in intergalactic scales and at redshift $z=30$, when typical galaxies are considered to form, which reads as $B\simeq 10^{-30}\mathrm{G}\left(\frac{\ell_\mathrm{R}}{10^6}\right)^2\left(\frac{M_\mathrm{PBH}}{10^{14}M_\odot}\right)^{5/2}$, where $M_\mathrm{PBH}$ is the PBH mass and $\ell_\mathrm{R}\equiv R_\mathrm{d}/R_\mathrm{ISCO}$, is the ratio of the radius of the disk, $R_\mathrm{d}$ over the radius of the innermost stable circular orbit, $R_\mathrm{ISCO}$. Interestingly enough, by requiring to seed a PMF of the order of $10^{-30}\mathrm{G}$ necessary to give rise to a present day $10^{-18}\mathrm{G}$ in intergalactic scales, we find a lower bound on the PBH mass within the range $[10^{10}- 10^{16}]M_\odot$ depending on the radius of the PBH disk.

Magnetic field enhanced thermal conductivity and origin of large thermopower in layered cobaltates

Cobalt oxide, as one of the most fascinating examples of correlated electronic system, exhibits several exotic transport characteristics, such as superconductivity, charge ordering, and topological frustration. In this study, we are reporting the observation of another intriguing transport phenomenon in calcium cobaltates. Specifically, under a large magnetic field of 7 T, we observed an anomalously enhanced thermal conductivity that was accompanied with a largely suppressed thermopower. This observation reveals a hitherto undiscovered correlation between the two transport factors. Within the premise of Heisenberg model, we have shown that the observed experimental results can be explained consistently only if the magnon excitation is taken into account. Our study offers an insight into the puzzling origin of large thermopower observed in layered cobaltates and provides a specific strategy for further optimization of thermopower.

A simple derivation of the Gertsenshtein effect

As shown by Gertsenshtein in 1961, an external magnetic field can catalyze the mixing of graviton and photon states in a manner analogous to neutrino-flavor oscillations. We first present a straightforward derivation of the mechanism by a method based on unpublished notes of Freeman Dyson. We next extend his method to include boundary conditions and retrieve the results of Boccaletti et al. from 1970. We point out that, although the coupling between the graviton and photon states is extremely weak, the large magnetic fields around neutron stars $\sim 10^{14}$ G make the Gertsenshtein effect a plausible source of gravitons. We also point out that axion-photon mixing, a subject of active current research, is essentially the same process as the Gertsenshtein effect, and so the general mechanism may be of broad astrophysical and cosmological interest.