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Electromagnetic field

Xinning Yu, Qian Ye, Huajin Chen, Shiyang Liu, Zhifang Lin
Based on an expansion formula for unit dyadic in terms of the vector spherical wave functions, we derive explicit partial wave coefficients for a complex wave vector field that is characterized by a single wave vector with three Cartesian components being arbitrarily constant complex except subject to lossless background constraint and thus includes evanescent waves and simple plasmonic fields as its two special cases. A recurrence method is then proposed to evaluate the partial wave expansion coefficients numerically up to arbitrary order of expansion, offering an efficient tool for the scattering of generic electromagnetic fields that can be modelled by a superposition of the complex wave vector fields such as the evanescent and plasmonic waves...
February 20, 2017: Optics Express
Duncan McArthur, Benjamin Hourahine, Francesco Papoff
We determine how to alter the properties of the quantum vacuum at ultraviolet wavelengths to simultaneously enhance the spontaneous transition rates and the far field detection rate of quantum emitters. We find the response of several complex nanostructures in the 200 - 400 nm range, where many organic molecules have fluorescent responses, using an analytic decomposition of the electromagnetic response in terms of continuous spectra of plane waves and discrete sets of modes. Coupling a nanorod with an aluminum substrate gives decay rates up to 2...
February 20, 2017: Optics Express
Zhaomin Tong, Wenjiang Shen, Shaohua Song, Wenzhi Cheng, Zhuo Cai, Yifei Ma, Lei Wei, Weiguang Ma, Liantuan Xiao, Suotang Jia, Xuyuan Chen
In high lumen laser projectors, it is required to use laser diodes coupled to multi-mode fibers (MMFs) to obtain a high power illumination module. In this paper, we have fabricated an electromagnetic micro-scanning mirror (EM-MSM), and we have firstly demonstrated a speckle reduction method by the combination of the EM-MSM and the MMF. With the help of a condenser lens, laser beams modulated and reflected from the EM-MSM are coupled into the MMF within its acceptance angle. Because the fast scanning behavior of the EM-MSM results in the phase modulation and mode coupling among the MMF guided modes, the light intensity field distributions at the exit aperture of the MMF are changing...
February 20, 2017: Optics Express
Wendy S L Lee, Korbinian Kaltenecker, Shruti Nirantar, Withawat Withayachumnankul, Markus Walther, Madhu Bhaskaran, Bernd M Fischer, Sharath Sriram, Christophe Fumeaux
As an alternative to metallic resonators, dielectric resonators can increase radiation efficiencies of metasurfaces at terahertz frequencies. Such subwavelength resonators made from low-loss dielectric materials operate on the basis of oscillating displacement currents. For full control of electromagnetic waves, it is essential that dielectric resonators operate around their resonant modes. Thus, understanding the nature of these resonances is crucial towards design implementation. To this end, an array of silicon resonators on a quartz substrate is designed to operate in transmission at terahertz frequencies...
February 20, 2017: Optics Express
Jacob Greene, Julien Louis, Olga Korostynska, Alex Mason
Muscle glycogen levels have a profound impact on an athlete's sporting performance, thus measurement is vital. Carbohydrate manipulation is a fundamental component in an athlete's lifestyle and is a critical part of elite performance, since it can provide necessary training adaptations. This paper provides a critical review of the current invasive and non-invasive methods for measuring skeletal muscle glycogen levels. These include the gold standard muscle biopsy, histochemical analysis, magnetic resonance spectroscopy, and musculoskeletal high frequency ultrasound, as well as pursuing future application of electromagnetic sensors in the pursuit of portable non-invasive quantification of muscle glycogen...
February 23, 2017: Biosensors
Xueguang Qiao, Zhihua Shao, Weijia Bao, Qiangzhou Rong
With the oil and gas industry growing rapidly, increasing the yield and profit require advances in technology for cost-effective production in key areas of reservoir exploration and in oil-well production-management. In this paper we review our group's research into fiber Bragg gratings (FBGs) and their applications in the oil industry, especially in the well-logging field. FBG sensors used for seismic exploration in the oil and gas industry need to be capable of measuring multiple physical parameters such as temperature, pressure, and acoustic waves in a hostile environment...
February 23, 2017: Sensors
Arno Thielens, Günter Vermeeren, Olivier Caytan, Guy Torfs, Piet Demeester, Johan Bauwelinck, Hendrik Rogier, Luc Martens, Wout Joseph
In the future, wireless radiofrequency (RF) telecommunications networks will provide users with gigabit-per-second data rates. Therefore, these networks are evolving toward hybrid networks, which will include commonly used macro- and microcells in combination with local ultra-high density access networks consisting of so-called attocells. The use of attocells requires a proper compliance assessment of exposure to RF electromagnetic radiation. This paper presents, for the first time, such a compliance assessment of an attocell operating at 3...
February 27, 2017: Bioelectromagnetics
Ying Xu, Heping Ying, Ya Jia, Jun Ma, Tasawar Hayat
Realistic neurons may hold complex anatomical structure, for example, autapse connection to some internuncial neurons, which this specific synapse can connect to its body via a close loop. Continuous exchanges of charged ions across the membrane can induce complex distribution fluctuation of intracellular and extracellular charged ions of cell, and a time-varying electromagnetic field is set to modulate the membrane potential of neuron. In this paper, an autapse-modulated neuron model is presented and the effect of electromagnetic induction is considered by using magnetic flux...
February 27, 2017: Scientific Reports
Hongxia Peng, Qin Huang, Tengyan Wu, Jin Wen, Hengping He
We constructed a novel mesoporous WO3 shell layered γ-Fe2O3@mWO3 (m was short for mesoporous) core-shell structured drug nano-carrier to investigate loading and controllable release properties of ibuprofen (IBU). This nanocomposite composed of mesoporous WO3 shell with magnetic γ-Fe2O3 core. They possesses high surface area of 100.09 m2/g, provides large accessible pore diameter of 6.0 nm for adsorption of drug molecules, high magnetization saturation value of 43.6 emu/g for drug targeting under foreign magnetic fields, quickly convert electromagnetic energy into thermal energy for controlled release by microwave-triggered which was caused by mWO3 shell...
February 24, 2017: Current Drug Delivery
Diego M Solís, José M Taboada, Fernando Obelleiro, Luis M Liz-Marzán, F Javier García de Abajo
Surface-enhanced Raman scattering (SERS) has become a widely used spectroscopic technique for chemical identification, providing unbeaten sensitivity down to the single-molecule level. The amplification of the optical near field produced by collective electron excitations -plasmons- in nanostructured metal surfaces gives rise to a dramatic increase by many orders of magnitude in the Raman scattering intensities from neighboring molecules. This effect strongly depends on the detailed geometry and composition of the plasmon-supporting metallic structures...
February 15, 2017: ACS Photonics
Vitalij Novickij, Eglė Lastauskienė, Jurgita Švedienė, Audrius Grainys, Gediminas Staigvila, Algimantas Paškevičius, Irutė Girkontaitė, Auksė Zinkevičienė, Svetlana Markovskaja, Jurij Novickij
Recently, a novel contactless treatment method based on high-power pulsed electromagnetic fields (PEMF) was proposed, which results in cell membrane permeabilization effects similar to electroporation. In this work, a new PEMF generator based on multi-stage Marx circuit topology, which is capable of delivering 3.3 T, 0.19 kV/cm sub-microsecond pulses was used to permeabilize pathogenic yeast Candida albicans separately and in combination with conventional square wave electroporation (8-17 kV/cm, 100 μs)...
February 25, 2017: Journal of Membrane Biology
Xinqiang Yan, John C Gore, William A Grissom
RF arrays with a large number of independent coil elements are advantageous for parallel transmission (pTx) and reception at high fields. One of the main challenges in designing RF arrays is to minimize the electromagnetic (EM) coupling between the coil elements. The induced current elimination (ICE) method, which uses additional resonator elements to cancel coils' mutual EM coupling, has proven to be a simple and efficient solution for decoupling microstrip, L/C loop, monopole and dipole arrays. However, in previous embodiments of conventional ICE decoupling, the decoupling elements acted as "magnetic-walls" with low transmit fields and consequently low MR signal near them...
February 16, 2017: Journal of Magnetic Resonance
Wilfredo González, Cécile Peucelle, Yolanda Prezado
PURPOSE: Charged particles have several advantages over x-rays radiations, both in terms of physics and radiobiology. The combination of these advantages with those of minibeam radiation therapy (MBRT) could help enhancing the therapeutic index for some cancers with poor prognosis. Among the different ions explored for therapy, carbon ions are considered to provide the optimum physical and biological characteristics. Oxygen could be advantageous due to a reduced oxygen enhancement ratio along with a still moderate biological entrance dose...
February 25, 2017: Medical Physics
Marta Parazzini, Serena Fiocchi, Emma Chiaramello, Yiftach Roth, Abraham Zangen, Paolo Ravazzani
Literature studies showed the ability to treat neuropsychiatric disorders using H1 coil, developed for the deep Transcranial Magnetic Stimulation (dTMS). Despite the positive results of the clinical studies, the electric field (E) distributions inside the brain induced by this coil when it is positioned on the scalp according to the clinical studies themselves are not yet precisely estimated. This study aims to characterize the E distributions due to the H1 coil in the brain of two realistic human models by computational electromagnetic techniques and to compare them with the ones due to the figure-of-8 coil, traditionally used in TMS and positioned as such to simulate the clinical experiments...
February 21, 2017: Medical Engineering & Physics
Hakkı Murat Bilgin, Ferhat Çelik, Mehmet Gem, Veysi Akpolat, İsmail Yıldız, Aysun Ekinci, Mehmet Siraç Özerdem, Selçuk Tunik
The effectiveness of various therapeutic methods on bone fracture has been demonstrated in several studies. In the present study, we tried to evaluate the effect of local low-magnitude, high-frequency vibration (LMHFV) on rat tibia fracture in comparison with pulsed electromagnetic fields (PEMF) during the healing process. Mid-diaphysis tibiae fractures were induced in 30 Sprague-Dawley rats. The rats were assigned into groups such as control (CONT), LMHFV (15 min/day, 7 days/week), and PEMF (3.5 h/day, 7 days/week) for a three-week treatment...
February 25, 2017: Bioelectromagnetics
Mikhail Kozlov, Elena Lucano, Leonardo M Angelone, Mikhail Kozlov, Elena Lucano, Leonardo M Angelone, Elena Lucano, Leonardo M Angelone, Mikhail Kozlov
This study investigates how the tuning conditions of a 64 MHz / 1.5 T radio frequency (RF) birdcage coil modeled with an RF circuit and 3D electromagnetic co-simulation affect the electric and magnetic near-field distribution. Four models were implemented with different tuning conditions and difference between numerical results and measurements was evaluated. The results show that the simulated near-field depends significantly on coil tuning conditions, especially in volumes close to the ASTM phantom walls...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Mikhail Kozlov, Gregor Schaefers, Mikhail Kozlov, Gregor Schaefers, Gregor Schaefers, Mikhail Kozlov
Radio frequency (RF) induced power deposition near straight insulated leads excited by different incident electrical field profiles was investigated. 3-D electromagnetic (EM) simulations were used to obtain implant models as well as RF-induced power depositions calculated as the integral of power loss density. For the investigated setups up to 400% discrepancy between the implant model predictions and EM simulation values was observed.
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Cristian A Torres-Valencia, M Claudia Joana Santamaria, Mauricio A Alvarez, Cristian A Torres-Valencia, M Claudia Joana Santamaria, Mauricio A Alvarez, Mauricio A Alvarez, Cristian A Torres-Valencia
Reconstruction of brain sources from magnetoencephalography and electroencephalography (M/EEG) data is a well known problem in the neuroengineering field. A inverse problem should be solved and several methods have been proposed. Low Resolution Electromagnetic Tomography (LORETA) and the different variations proposed as standardized LORETA (sLORETA) and the standardized weighted LORETA (swLORETA) have solved the inverse problem following a non-parametric approach, that is by setting dipoles in the whole brain domain in order to estimate the dipole positions from the M/EEG data and assuming some spatial priors...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
A F Restrepo, V E Tobar, R J Camargo, E Franco, C R Pinedo, O Gutierrez, A F Restrepo, V E Tobar, R J Camargo, E Franco, C R Pinedo, O Gutierrez, C R Pinedo, E Franco, R J Camargo, V E Tobar, O Gutierrez, A F Restrepo
This paper presents the cellular proliferation effects of the exposure to extremely low frequency electromagnetic fields (ELF-EMF) on in-vitro cellular cultures HeLa and CHO. Through the magnetic stimulation system (MSS) the cells were exposed to magnetic fields with sinusoidal waveform at 50 Hz; initially for 40 minutes at intensities of 0.4 mT, 1.4 mT, 2.13 mT, 2.49 mT and 2.53 mT in parallel and perpendicular directions to the culture plates. Subsequently, the repetitive electromagnetic field (rEMF) was applied to 2...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
Kumaradevan Punithakumar, Abhilash R Hareendranathan, Riitta Paakkanen, Nehan Khan, Michelle Noga, Pierre Boulanger, Harald Becher, Kumaradevan Punithakumar, Abhilash R Hareendranathan, Riitta Paakkanen, Nehan Khan, Michelle Noga, Pierre Boulanger, Harald Becher, Harald Becher, Nehan Khan, Riitta Paakkanen, Michelle Noga, Kumaradevan Punithakumar, Abhilash R Hareendranathan, Pierre Boulanger
Three-dimensional ultrasound is an emerging modality for the assessment of complex cardiac anatomy and function. The advantages of this modality include lack of ionizing radiation, portability, low cost, and high temporal resolution. Major limitations include limited field-of-view, reliance on frequently limited acoustic windows, and poor signal to noise ratio. This study proposes a novel approach to combine multiple views into a single image using an electromagnetic tracking system in order to improve the field-of-view...
August 2016: Conference Proceedings: Annual International Conference of the IEEE Engineering in Medicine and Biology Society
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