Effect of interplanetary magnetic field B_(x)on the polar electrojets as observed by CHAMP and Swarm satellites

Based on 16 years of magnetic field observations from CHAMP and Swarm satellites,this study investigates the influence of the Interplanetary Magnetic Field(IMF)Bx component on the location and peak current density of the polar electrojets(PEJs).We find that the IMF Bx displays obvious local time,seasonal,and hemispherical effects on the PEJs,as follows:(1)Compared to other local times,its influence is weakest at dawn and dusk.(2)In the midnight sectors of both hemispheres,the IMF Bx tends to amplify the westward PEJ when it is<0 in the Northern Hemisphere and when it is>0 in the Southern Hemisphere;this effect is relatively stronger in the local winter hemisphere.(3)At noontime,the IMF Bx intensifies the eastward current when it is<0 in the Northern Hemisphere;in the Southern Hemisphere when it is>0,it reduces the westward current;this effect is notably more prominent in the local summer hemisphere.(4)Moreover,the noontime eastward current shifts towards higher latitudes,while the midnight westward current migrates towards lower latitudes when IMF Bx is<0 in the Northern Hemisphere and when it is>0 in the Southern Hemisphere.

Integrated multi-scale approach combining global homogenization and local refinement for multi-field analysis of high-temperature superconducting composite magnets

Second-generation high-temperature superconducting(HTS)conductors,specifically rare earth-barium-copper-oxide(REBCO)coated conductor(CC)tapes,are promising candidates for high-energy and high-field superconducting applications.With respect to epoxy-impregnated REBCO composite magnets that comprise multilayer components,the thermomechanical characteristics of each component differ considerably under extremely low temperatures and strong electromagnetic fields.Traditional numerical models include homogenized orthotropic models,which simplify overall field calculation but miss detailed multi-physics aspects,and full refinement(FR)ones that are thorough but computationally demanding.Herein,we propose an extended multi-scale approach for analyzing the multi-field characteristics of an epoxy-impregnated composite magnet assembled by HTS pancake coils.This approach combines a global homogenization(GH)scheme based on the homogenized electromagnetic T-A model,a method for solving Maxwell's equations for superconducting materials based on the current vector potential T and the magnetic field vector potential A,and a homogenized orthotropic thermoelastic model to assess the electromagnetic and thermoelastic properties at the macroscopic scale.We then identify“dangerous regions”at the macroscopic scale and obtain finer details using a local refinement(LR)scheme to capture the responses of each component material in the HTS composite tapes at the mesoscopic scale.The results of the present GH-LR multi-scale approach agree well with those of the FR scheme and the experimental data in the literature,indicating that the present approach is accurate and efficient.The proposed GH-LR multi-scale approach can serve as a valuable tool for evaluating the risk of failure in large-scale HTS composite magnets.

Effects of low-frequency repetitive transcranial magnetic stimulation on electroencephalogram and seizure frequency in 15 patients with temporal lobe epilepsy following dipole source localization

BACKGROUND： Low-frequency repetitive transcranial magnetic stimulation （rTMS） has been shown to significantly reduce epileptiform discharges and control clinical seizures in intractable epilepsy patients. The location of epileptic foci and magnetic stimulation sites remain uncertain. The effects of rTMS on electroencephalogram and seizure remain unclear in epileptic patients following dipole source localization. OBJECTIVE： To investigate the effects of low-frequency rTMS on electroencephalogram and seizure in temporal lobe epilepsy patients after dipole source localization. DESIGN, TIME AND SETTING： The randomized, controlled study was performed at the outpatient clinic Department of Neurology, Hospital Affiliated to North Sichuan Medical College from December 2003 to February 2007. PARTICIPANTS： A total of 30 temporal lobe epilepsy patients, comprising 19 males and 11 females, aged 1749 years, presented with epileptiform discharges and were enrolled for this study. Disease course ranged between 1-6 years, with 1-5 seizures per month. Imaging examinations revealed 11 patients with structural changes in the brain. The patients were randomly and equally assigned into drug treatment and transcranial magnetic stimulation （TMS） groups. METHODS： Patients in the drug treatment group were orally treated with carbamazepine. Patients in the TMS group received oral carbamazepine treatment of and TMS. A Maglite-r25 magnetic stimulator （Dantec Dynamics, Denmark） was used to stimulate epileptic foci in the temporal lobe following electroencephalogram dipole localization （1 Hz, 90% threshold intensity, at a stimulation frequency of 500 times, once a day, for 7 days）. MAIN OUTCOME MEASURES： At 30 days after TMS, seizure frequency and rate of epileptiform discharges were observed in patients from both groups. Therapeutic safety was investigated during treatment. RESULTS： Within 30 days of treatment, there were no significant differences in seizure frequency between the TMS group （1.5 ± 0.3） seizures and the drug treatment group [（1.9± 0.4） seizures] （P 〉 0.05）. The rate of epileptiform discharges [27% （4/15）] was significantly less in the TMS group than in the drug treatment group [73% （11/15）] （P 〈 0.05）. During TMS, five patients suffered from transient mild headache, but were completely relieved within 2 hours. CONCLUSION： Low-frequency rTMS exhibited inhibitory effects on epileptiform discharges over a short period of time, and decreased seizure frequency to some degree. Results from the present study suggested that low-frequency rTMS is safe.

Ensembling Neural Networks for User’s Indoor Localization Using Magnetic Field Data from Smartphones

Predominantly the localization accuracy of the magnetic field-based localization approaches is severed by two limiting factors:Smartphone heterogeneity and smaller data lengths.The use of multifarioussmartphones cripples the performance of such approaches owing to the variability of the magnetic field data.In the same vein,smaller lengths of magnetic field data decrease the localization accuracy substantially.The current study proposes the use of multiple neural networks like deep neural network(DNN),long short term memory network(LSTM),and gated recurrent unit network(GRN)to perform indoor localization based on the embedded magnetic sensor of the smartphone.A voting scheme is introduced that takes predictions from neural networks into consideration to estimate the current location of the user.Contrary to conventional magnetic field-based localization approaches that rely on the magnetic field data intensity,this study utilizes the normalized magnetic field data for this purpose.Training of neural networks is carried out using Galaxy S8 data while the testing is performed with three devices,i.e.,LG G7,Galaxy S8,and LG Q6.Experiments are performed during different times of the day to analyze the impact of time variability.Results indicate that the proposed approach minimizes the impact of smartphone variability and elevates the localization accuracy.Performance comparison with three approaches reveals that the proposed approach outperforms them in mean,50%,and 75%error even using a lesser amount of magnetic field data than those of other approaches.

Researches on Magnetic Localization for Detecting Capsule in Gastrointestinal Tract

Recently, the capsule detection for examination of gastrointestinal (GI) tract became a novel noninvasive system, but it was still a problem for capsule’s location. This paper examined various technologies used for measuring position based on magnetic method of the capsule in GI tract, while some new methods were investigated and their efficiency and complexity were analyzed. The results show that the radio frequency location is only practicable, but the tri-coil stimulating magnetic method and magnetic marker method can help to acquire a high precise, simplified, efficient and localized device.

Robust Local Weighted Regression for Magnetic Map-Based Localization on Smartphone Platform

The magnetic information measured on the smartphone platform has a large fluctuation and the research of indoor localization algorithm based on smart-phone platform is less. Indoor localization algorithm on smartphone platform based on particle filter is studied. Robust local weighted regression is used to smooth the original magnetic data in the process of constructing magnetic map. Use moving average filtering model to filter the online magnetic observation data in positioning process. Compare processed online magnetic data with processed magnetic map collected by smartphone platform and the average matching error is 0.3941uT. Average positioning error is 0.229 meter when using processed online and map data.

Magnetic resonance imaging for diagnosis and neoadjuvant treatment evaluation in locally advanced rectal cancer:A pictorial review

High-resolution pelvic magnetic resonance imaging(MRI) is the primary method for staging rectal cancer.MRI is highly accurate in the primary staging of rectal cancer;however,it has not proven to be effective in restaging,especially in complete response evaluation after neoadjuvant therapy.Neoadjuvant chemoradiotherapy produces many changes in rectal tumors and on adjacent area,as a result,local tumor extent may not be accurately determined.However,adding diffusion-weighted sequences to the standard approach can improve diagnostic accuracy.In this pictorial review,an overview of the situation of MRI in the staging and re-staging of rectal cancer is exhibited as a pictorial assay.An experience-and literature-based discussion of limitations and difficulties in interpretation are also presented.

Quantitative Detection of Corrosion State of Concrete Internal Reinforcement Based on Metal Magnetic Memory

Corrosion can be very harmful to the service life and several properties of reinforced concrete structures.The metal magnetic memory(MMM)method,as a newly developed spontaneous magnetic flux leakage(SMFL)non-destructive testing(NDT)technique,is considered a potentially viable method for detecting corrosion damage in reinforced concrete members.To this end,in this paper,the indoor electrochemical method was employed to accelerate the corrosion of outsourced concrete specimens with different steel bar diameters,and the normal components Bz and its gradient of the SMFL fields on the specimen surfaces were investigated based on the metal magnetic memory(MMM)method.The experimental results showed that the SMFL experimental Bz curves are consistent with the analytical results of the theoretical model.Furthermore,the crest-to-trough behavior on the Bz signal curve and its zero-point gradient spacing can more accurately indicate the corroded area’s extent.Then,a magnetic characteristic parameter W based on a large amount of experimental data was established to characterize the degree of corrosion of the steel bars.The magnetic characteristic parameter W is linearly related to the maximum cross-sectional area loss rate
of the corroded reinforcement.This paper will lay the foundation for future research on corrosion detection of reinforced concrete structures based on the MMM method and provide a feasible way for non-destructive detection of corrosion independent of the influence of reinforcement diameter and magnetization history.

Fast local wavenumber （FLW） method for the inversion of magnetic source parameters

The current local wavenumber methods for the interpretation of magnetic anomalies compute the locations of geological bodies by solving complex matrices. Presently, such methods require to know the structural index, which is a parameter that represents the source type. The structural index is hard to know in real data; consequently, the precision of current methods is low. We present the fast local wavenumber （FLW） method, and define the squared sum of the horizontal and vertical local wavenumbers as the cumulative local wavenumber. The FLW method is the linear combination of the umulative local wavenumberand other wavenumbers, and is used to compute the locations and structural index of the source without a priori information and matrix solution. We apply the FLW method to synthetic magnetic anomalies, and the results suggest that the FLW method is insensitive to background and oblique magnetization. Next, we apply the FLW method to real magnetic data to obtain the location and structural index of the source.

A wireless magnetic sensor for localizing in-vivo medical micro-devices

In order to measure the position and orientation of in-vivo medical micro-devices without the line-of- sight constraints, a wireless magnetic sensor is developed for an electromagnetic localization method. In the electromagnetic localization system, the wireless magnetic sensor is embedded in the micro-devices to measure alternating magnetic signals. The wireless magnetic sensor is composed of an induction coil, a signal processor, a radio frequency （R.F） transmitter, a power manager and batteries. Based on the principle of electromagnetic induction, the induction coil converts the alternating magnetic signals into electrical signals. Via the RF transmitter, the useful data am wirelessly sent outside the body. According to the relation between the magnetic signals and the location, the position and orientation of the micro-devices can be calculated. The experiments demonstrate the feasibility of localizing in-vivo medical micro-devices with the wireless magnetic sensor. The novel localization system is accurate and robust.

Accelerations in the Local Magnetic Field on the Adriatic Tectonic Microplate

The high level of noise is a special feature of the geomagnetic field on the territory of Slovenia. The tension of the Adriatic tectonic microplate, on which Slovenia entirely lies, was recognized as one of its sources. The interior of the Earth is also the source of geomagnetic jerks. They are impulses in the secular variation calculated on the basis of monthly or annual mean values of variation of the geomagnetic field. The paper presents an analysis of accelerations in a local magnetic field calculated on the bases of daily mean values of the magnetic field measured at PIA geomagnetic Observatory (Piran, Slovenia) in 2020. These accelerations indicate geomagnetic impulses at the regional level over days or weeks. Then these results are compared with the registered seismic activity in the West Balkans.

Interaction and local magnetic moments of metal phthalocyanine and tetraphenylporphyrin molecules on noble metal surfaces

In order to understand the Kondo effect observed in molecular systems, first-principles calculations have been widely used to predict the ground state properties of molecules on metal substrates. In this work, the interaction and the local magnetic moments of magnetic molecules （3d-metal phthalocyanine and tetraphenylporphyrin molecules） on noble metal surfaces are investigated based on the density functional theory. The calculation results show that the dz2 orbital of the transition metal atom of the molecule plays a dominant role in the molecule-surface interaction and the adsorption energy exhibits a simple declining trend as the adsorption distance increases. In addition, the Au（111） surface generally has a weak interaction with the adsorbed molecule compared with the Cu（ll 1） surface and thus serves as a better candidate substrate for studying the Kondo effect. The relation between the local magnetic moment and the Coulomb interaction U is examined by carrying out the GGA＋U calculation according to Dudarev＇s scheme. We find that the Coulomb interaction is essential for estimating the local magnetic moment in molecule-surface systems, and we suggest that the reference values of parameter U are 2 eV for Fe and 2-3 eV for Co.

Local structure distortion and spin Hamiltonian parameters of oxide-diluted magnetic semiconductor Mn-doped ZnO

The local structure distortion, the spin Hamiltonian （SH） parameters, and the electric fine structure of the ground state for Mn^2＋ （3d^5） ion in ZnO crystals are systematically investigated, where spin-spin （SS）, spin-other-orbit （SOO） and orbit-orbit （OO） magnetic interactions, besides the well-known spin-orbit （SO） coupling, are taken into account for the first time, by using the complete diagonalization method. The theoretical results of the second-order zerofield splitting （ZFS） parameter D, the fourth-order ZFS parameter （a-F）, the Zeeman g-factors： g// and g⊥, and the energy differences of the ground state： δ1 and δ2 for Mn^2＋ in Mn^2＋： ZnO are in good agreement with experimental measurements when the three O^2- ions below the Mn^2＋ ion rotate by 1.085° away from the [111]-axis. Hence, the local structure distortion effect plays an important role in explaining the spectroscopic properties of Mn^2＋ ions in Mn^2＋： ZnO crystals. It is found for Mn^2＋ ions in Mn^2＋： ZnO crystals that although the SO mechanism is the most important one, the contributions to the SH parameters, made by other four mechanisms, i.e. SS, SOO, OO, and SO-SS-SOO-OO mechanisms, are significant and should not be omitted, especially for calculating ZFS parameter D.

Controlled Local Hyperthermia and Magnetic Hyperthermia of Surface (Skin) Cancer Diseases

Average size of hematite and magnetite micro and nanopowders and polydispersity index, zeta potential and distribution of particles were studied. Analysis showed that average size of the obtained particles for magnetite is 740.9 nm, for hematite particles 30 - 35 nm. Alternate current feed source was created for hyperthermia. Proceeding from the requirements of the objectives, the U type MnZn material magneto conductors were selected, in which 10.0 and 8.0 mm width gaps were cut and glass test tubes with magnetite or hematite suspensions were placed in them. Series of experiments at various field intensity and frequencies showed that for efficient magnetic hyperthermia therapy more powerful device was needed with frequency of up to 10 Mega Hertz to achieve the temperature 43°C - 45°C necessary for full activation of Neel and Brown mechanisms in particles. At the next stage, on the basis of experimental material the anticancer mono-therapeutic effect of hyperthermia and its adjuvant action in poly chemotherapeutic treatment was presented by the use of a device created by us “Lezi”. As a result of the experiment it was shown that in all animals (outbred albino mice, 3 months old) inhibition of cancer growth was fixed and intratumoral necrosis was developed, while after 7 and 10 sessions tumors were ulcerated, which refers to positive effect of the experiment (Conclusion of Pathologicanatomical Laboratory “PATGEO”, Tbilisi, Georgia ).

Localization for the Non-Invasive Detecting Capsule in GI Tract Utilizing Permanent Magnet and Magnetoresistive Sensors

The paper reports the localization principle and method for the capsule in the non-invasive detecting system of gastrointestinal （GI） tract utilizing one permanent and three magnetoresistive sensors. When the capsule is localized in practice, the permanent magnet is fixed inside the capsule, and the four magnetoresistive sensors are installed outside body. The permanent magnet＇s coordinate values can be solved by the magnetic dipole theory and optimum iterated method. The experiment shows the localization distance can reach 300mm by employing the HMC1023 magnetoresistive sensors and the NdFeB45 09 mm × 5 mm permanent magnet, and the errors of single coordinate direction and radius vector are 0 - 58 mm and 0.1-62.9 nun respectively. The localization precision is acceptable basically, and it has some possibilities improving the precision and distance in the future. Moreover, the localization system makes the localization be reality because of decreasing the number of sensors, and it economizes the capsule＇s volume because of decreasing the permanent magnet＇s dimension, too.

Role of magnetic resonance imaging in the diagnostic work up of clinical localized prostate cancer: A review

Imaging plays an increasingly important role in the work up of prostate cancer(PCa) and magnetic resonance imaging(MRI) is generally accepted as the most accurate and promising imaging modality in the local staging of PCa due to its high spatial resolution and excellent soft tissue contrast. The quality and performance of MRI of the prostate has improved dramatically during the last decade. Mainly, the combination of morphological information and functional information on cell density, tissue perfusion or metabolism as provided in multi-parametric prostate MRI(mp MRI) has led to a substantial increase in lesion detection and characterization. The correlation between functional parameters as provided by MRI and the aggressiveness of PCa as determined by the Gleason Score may help in differentiating clinically signifi cant from indolent PCa non-invasively. Besides these pros, radiologists are confronted with an immense amount of information and standardized acquisition, interpretation and reporting of mp MRI is not yet a reality. Furthermore, prostate MRI availability is still limited to high volume centers in many countries; hence, it is not yet a routine tool in common daily practice. Hence, development of guidelines for standardized acquisition, interpretation andreporting of prostate MRI exams is urgently needed in order to provide useful information for treating clinicians. Preferably, multi-centric clinical studies comparing MRI fi ndings to step-section histological specimens are mandatory during the coming years. Furthermore, simplification of the acquisition must be achieved in order to make this imaging modality applicable for daily use in common uro-radiological practice.

A novel localization and orientation method for an objective embedded with a rectangle magnet

To wirelessly obtain the accurate location and orientation of an objective and exert an appropriate guidance for the objective, a feasible approach is to enclose a small rectangular permanent mag- net in the objective. The magnetic field, produced by the rectangular magnet can be detected by magnetic sensors outside the objective. With these sensor data, the 3D localization and 3D orienta- tion parameters can be computed based on the mathematic model of the rectangular magnet magnetic field. In this 6D localization and orientation system, we first obtain 5D parameters of the objective by dipole model, then based on these parameters we can obtain 6D parameters by the model of rectangular magnet magnetic field using the particle swarm optimization （PSO） algorithm. Simulation experiments show that the proposed approach achieves ~ood performance.

Directional Filter, Local Frequency Estimate and Algebraic Inversion of Differential Equation of Psoas Major Magnetic Resonance Elastography

Magnetic resonance elastography (MRE) can visualize the shear wave propagation of in vivo tissues, which can be mapped into viscoelastic properties. No study has measured the biomechanical properties of the PM muscle in vivo using MRE. In this study, we evaluated stiffness values calculated by local frequency estimate (LFE) and algebraic inversion of differential equation (AIDE) in PM-MRE. The PM muscles of 17 healthy male volunteers were scanned in supine position by MRE. The Laplacian-based estimate (LBE) phase wrapped image data were filtered by gaussian-bandpass filter (GBF), and by both directional and GBF. LFE (MREWave) and AIDE wave inversion methods were used to calculate the respective elastograms. The wave interferences were removed by directional filtering, and smooth wave fields were obtained. The stiffness values calculated by LFE of non-DF images were 1.39 ± 0.25 kPa and 1.33 ± 0.22 kPa for right and left PM respectively, whereas for DF images, they were 1.26 ± 0.20 kPa for right PM and 1.18 ± 0.28 kPa for left PM. The stiffness values calculated by AIDE of non-DF images were 0.78 ± 0.10 kPa and 0.78 ± 0.13 kPa for right and left PM respectively, whereas for DF images, they were 0.73 ± 0.12 kPa for right PM and 0.74 ± 0.11 kPa for left PM. There was no statistically significant difference in mean values of stiffness with/without applying directional filter whereas there was a statistically significant difference in mean values of stiffness between LFE and AIDE. Both LFE and AIDE could be used for psoas major MR Elastography.

Diffusion-weighted magnetic resonance imaging for predicting the response of rectal cancer to neoadjuvant concurrent chemoradiation

AIM:To evaluate the clinical value of diffusion-weighted magnetic resonance imaging(DW-MRI)in predicting the response of rectal cancer to neoadjuvant chemoradiation.METHODS:This prospective study was approved by our institutional review board,and informed consent was obtained from each patient.Fifteen patients(median age 56 years)with locally advanced rectal cancer were treated in our hospital from June 2006 to December 2007.All patients were stageⅢB-C according to the results of MRI and endorectal ultrasound examinations.All patients underwent pelvic irradiation with 45 Gy/25 fx per 35 days.The concurrent chemotherapy regimen consisted of capecitabine 625mg/m2,bid(Monday-Friday),and oxaliplatin 50 mg/m2,weekly.The patients underwent surgery 5-8 wk after the completion of neoadjuvant therapy.T downstaging was defined as the downstaging of the tumor from cT3to ypT0-2 or from cT4 to ypT0-3.Good regression was defined as TRG 3-4,and poor regression was defined as TRG 0-2.Diffusion-weighted magnetic resonance images were obtained prior to and weekly during the course of neoadjuvant chemoradiation,and the apparent diffusion coefficient(ADC)values were calculated from the acquired tumor images.RESULTS:Comparison with the mean pretreatment tumor ADC revealed an increase in the mean tumor ADC during the course of neoadjuvant chemoradiation,especially at the 2ndweek(P=0.004).We found a strong negative correlation between the mean pretreatment tumor ADC and tumor regression after neoadjuvant chemoradiation(P=0.021).In the T downstage and tumor regression groups,we found a significant increase in the mean ADC at the 2ndweek of neoadjuvant therapy(P=0.011;0.004).CONCLUSION:DW-MRI might be a valuable clinical tool to help predict or assess the response of rectal cancer to neoadjuvant chemoradiation at an early timepoint.

Metal magnetic memory field characterization at early fatigue damage based on modified Jiles-Atherton model

In order to propel the development of metal magnetic memory （MMM） technique in fatigue damage detection, the Jiles-Atherton model （J-A model） was modified to describe MMM mechanism in elastic stress stage. A series of rotating bending fatigue experiments were conducted to study the stress-magnetization relationship and verify the correctness of modified J-A model. In MMM detection, the magnetization of material irreversibly approaches to the local equilibrium state Mo instead of global equilibrium state M^n under cyclic stress, and the M0-a curves are loops around the Mar,-a curve. The modified J-A model is constructed by replacing M~ in J-A model with M0, and it can describe the magnetomechanical effect well at low external magnetic field. In the rotating bending fatigue experiments, the MMM field distribution in normal direction around cylinder specimen is similar to the stress distribution, and the calculation result of model coincides with experiment result after some necessary modifications. The MMM field variation with time at a certain point in fatigue process is divided into three stages with the variation of stable stress-stain hysteresis loop, and the calculation results of model can explain not only the three stages of MMM field changes, but also the different change laws when the applied magnetic field and initial magnetic field are different. The MMM field distribution in normal direction along specimen axis reflects stress concentration effect at artificial defect, and the magnetic signal fluctuates around the defect at late fatigue stage. The calculation results coincide with the initial MMM principle and can explain signal fluctuates around the defect. The modified J-A model can explain experiment results well, and it is fit for MMM field characterization.