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electromagnetic fields body

Can Hu, Jie Feng, Sherman Xuegang Xin
Numerical electromagnetic models that can mimic the dielectric properties of human tissues have been widely used for dosimetry-related studies in bio-electromagnetics, particularly for the calculation of electromagnetic field distribution inside the human body, which is subject specific. Reports indicated that considerable electromagnetic field variations may occur inside different human subjects even when existing differences in the geometrical dimensions of these subjects are minimal. Therefore, a subject-specific three-dimensional (3D) electromagnetic model is crucially required to calculate the electromagnetic field distribution accurately...
July 31, 2018: Computers in Biology and Medicine
Prashanth S Venkataram, Jan Hermann, Alexandre Tkatchenko, Alejandro W Rodriguez
Thermal radiative phenomena can be strongly influenced by the coupling of phonons and long-range electromagnetic fields at infrared frequencies. Typically employed macroscopic descriptions of thermal fluctuations often ignore atomistic effects that become relevant at nanometric scales, whereas purely microscopic treatments ignore long-range, geometry-dependent electromagnetic effects. We describe a mesoscopic framework for modeling thermal fluctuation phenomena among molecules near macroscopic bodies, conjoining atomistic treatments of electronic and vibrational fluctuations obtained from density functional theory in the former with continuum descriptions of electromagnetic scattering in the latter...
July 27, 2018: Physical Review Letters
Mathias Davids, Bastien Guérin, Axel Vom Endt, Lothar R Schad, Lawrence L Wald
PURPOSE: As gradient performance increases, peripheral nerve stimulation (PNS) is becoming a significant constraint for fast MRI. Despite its impact, PNS is not directly included in the coil design process. Instead, the PNS characteristics of a gradient are assessed on healthy subjects after prototype construction. We attempt to develop a tool to inform coil design by predicting the PNS thresholds and activation locations in the human body using electromagnetic field simulations coupled to a neurodynamic model...
August 9, 2018: Magnetic Resonance in Medicine: Official Journal of the Society of Magnetic Resonance in Medicine
Federica Facchin, Eva Bianconi, Silvia Canaider, Valentina Basoli, Pier Mario Biava, Carlo Ventura
The human body constantly regenerates after damage due to the self-renewing and differentiating properties of its resident stem cells. To recover the damaged tissues and regenerate functional organs, scientific research in the field of regenerative medicine is firmly trying to understand the molecular mechanisms through which the regenerative potential of stem cells may be unfolded into a clinical application. The finding that some organisms are capable of regenerative processes and the study of conserved evolutionary patterns in tissue regeneration may lead to the identification of natural molecules of ancestral species capable to extend their regenerative potential to human tissues...
2018: Stem Cells International
Valentina Hartwig, Giorgio Virgili, Luca Fabiano Ferrante Vero, Daniele De Marchi, Luigi Landini, Giulio Giovannetti
Magnetic resonance imaging (MRI) is one of the most common sources of electromagnetic (EM) fields as a diagnostic technique widely used in medicine. MRI staff during the working day is constantly exposed to static and spatially heterogeneous magnetic field. Also, moving around the MRI room to perform their functions, workers are exposed to slowly time-varying magnetic fields that induce electrical currents and fields in the body. The development of new exposure assessment methodologies to collect exposure data at a personal level using simple everyday equipment is hence necessary, also in view of future epidemiological studies...
July 20, 2018: Radiation Protection Dosimetry
Atsushi Saito, Tatsuya Terai, Kei Makino, Masayuki Takahashi, Sachiko Yoshie, Masateru Ikehata, Yasuhiko Jimbo, Keiji Wada, Yukihisa Suzuki, Satoshi Nakasono
Threshold values of neuronal stimulation and modulation associated with exposure to time-varying electromagnetic fields contribute to establishing human protection guidelines and standards. However, biological evidence of threshold values in the intermediate-frequency range is limited. Additionally, although it is known that dendrites, a type of unmyelinated neuronal fibre, play an important role in information processing in the central nervous system, the stimulus threshold in dendrites has not been sufficiently investigated...
August 1, 2018: Integrative Biology: Quantitative Biosciences From Nano to Macro
Birşen Bilgici, Seda Gun, Bahattin Avci, Ayşegül Akar, Begüm K Engiz
PURPOSE: To investigate the inflammatory effect and testicular damage on rats exposed to low level of electromagnetic fields (EMF) at 2.45 GHz microwave radiation. METHODS: Twenty two Wistar rats were divided into two groups. Group 1 was the control group and not exposed to EMF. Group 2 was exposed to low level EMF (average E-field 3.68± 0.36 V/m, whole body average SAR, 0.0233W/kg, in 10g tissue) at 2.45 GHz for 1 hour/day for 30 consecutive days. At the end of the study, interleukin-6 (IL-6), interleukin-10 (IL-10), interleukin-32 (IL-32), C-reactive protein (CRP) were measured in rat serum and IL-6, IL-10, IL-32 were measured in rat testis tissue...
July 20, 2018: International Journal of Radiation Biology
Dominique Belpomme, Lennart Hardell, Igor Belyaev, Ernesto Burgio, David O Carpenter
Exposure to low frequency and radiofrequency electromagnetic fields at low intensities poses a significant health hazard that has not been adequately addressed by national and international organizations such as the World Health Organization. There is strong evidence that excessive exposure to mobile phone-frequencies over long periods of time increases the risk of brain cancer both in humans and animals. The mechanism(s) responsible include induction of reactive oxygen species, gene expression alteration and DNA damage through both epigenetic and genetic processes...
July 6, 2018: Environmental Pollution
Elfide Gizem Kıvrak, Kıymet Kübra Yurt, Arife Ahsen Kaplan, Işınsu Alkan, Gamze Altun
Technological devices have become essential components of daily life. However, their deleterious effects on the body, particularly on the nervous system, are well known. Electromagnetic fields (EMF) have various chemical effects, including causing deterioration in large molecules in cells and imbalance in ionic equilibrium. Despite being essential for life, oxygen molecules can lead to the generation of hazardous by-products, known as reactive oxygen species (ROS), during biological reactions. These reactive oxygen species can damage cellular components such as proteins, lipids and DNA...
October 2017: Journal of microscopy and ultrastructure
Reijer L Leijsen, Wyger M Brink, Cornelis A T van den Berg, Andrew G Webb, Rob F Remis
Contrast source inversion - electrical properties tomography (CSI-EPT) is an iterative reconstruction method to retrieve the electrical properties (EPs) of tissues from MR data. The method is based on integral representations of the electromagnetic (EM) field and has been shown to allow EP reconstructions of small structures as well as tissue boundaries with compelling accuracy. However, to date CSI-EPT has been implemented for two-dimensional (2D) configurations only which limits its applicability. In this paper, a full three-dimensional (3D) extension of the CSI-EPT method is presented, to enable CSI-EPT to be applied to realistic 3D scenarios...
May 18, 2018: IEEE Transactions on Medical Imaging
Mikhail Zubkov, Anna A Hurshkainen, Ekaterina A Brui, Stanislav B Glybovski, Mikhail V Gulyaev, Nikolai V Anisimov, Dmitry V Volkov, Yury A Pirogov, Irina V Melchakova
Particular applications in preclinical magnetic resonance imaging require the entire body of an animal to be imaged with sufficient quality. This is usually performed by combining regions scanned with small coils with high sensitivity or long scans using large coils with low sensitivity. Here, a metamaterial-inspired design employing a parallel array of wires operating on the principle of eigenmode hybridization was used to produce a small-animal imaging coil. The coil field distribution responsible for the coil field of view and sensitivity was simulated in an electromagnetic simulation package and the coil geometrical parameters were optimized for whole-body imaging...
June 26, 2018: NMR in Biomedicine
Saber Nankali, Esben S Worm, Rune Hansen, Britta Weber, Morten Høyer, Alireza Zirak, Per Rugaard Poulsen
The accuracy of stereotactic body radiotherapy (SBRT) in the liver is limited by tumor motion. Selection of the most suitable motion mitigation strategy requires good understanding of the geometric and dosimetric consequences. This study compares the geometric and dosimetric accuracy of actually delivered respiratory gated SBRT treatments for 15 patients with liver tumors with three simulated alternative motion adaptation strategies. The simulated alternatives are MLC tracking, baseline shift adaptation by inter-field couch corrections and no intrafraction motion adaptation...
July 16, 2018: Physics in Medicine and Biology
Qi Zeng, Qinyan Wang, Jianfeng Zheng, Wolfgang Kainz, Ji Chen
A typical cochlear implant system under magnetic resonance imaging (MRI) procedures may couple with the radio frequency (RF) electromagnetic field (EMF) and results in an intensified electric field at the lead tip. As a result, the RF energy deposited in human tissues around the lead tip may induce heating and cause tissue damage concerns. The purpose of this work is to evaluate the RF-EMF-induced heating for cochlear implant system in 1.5 T MRI coil and highlight the factors that have significant effects on the heating...
July 6, 2018: Physics in Medicine and Biology
Marcy C Purnell, Matthew B A Butawan, Risa D Ramsey
Erythrocytes must maintain a biconcave discoid shape in order to efficiently deliver oxygen (O2 ) molecules and to recycle carbon dioxide (CO2 ) molecules. The erythrocyte is a small toroidal dielectrophoretic (DEP) electromagnetic field (EMF) driven cell that maintains its zeta potential (ζ) with a dielectric constant (ԑ) between a negatively charged plasma membrane surface and the positively charged adjacent Stern layer. Here, we propose that zeta potential is also driven by both ferroelectric influences (chloride ion) and ferromagnetic influences (serum iron driven)...
June 2018: Physiological Reports
Roshen Borkar, James Rizkalla, Youngmin Kwon, Paul Salama, Maher Rizkalla
Diabetic foot ulcers are systemic diseases that affect all blood vessels within the human body. From major blood vessels to microvasculature, hardening, thickening, and narrowing of blood vessels ultimately results to diminished blood flow to end organs. The detrimental effects of peripheral vascular disease are well recognized across medicine, particularly with regards to diabetic foot ulcers. Diabetic foot ulcers (DFU) are common across all fields of medicine, including but not limited to: orthopedics, vascular surgery, podiatry, general internal medicine, and infectious disease...
June 2018: Journal of Orthopaedics
Varshini Karthik, T Rama Rao
Wearable electronics have become the norm over the last few years. Extensive use of wearable wireless devices (WWD) in greater proximity to the body has increased concern about potential biological effects due to the interaction of human tissues with electromagnetic (EM) fields. Human tissues absorb radiofrequency (RF) waves that are capable of affecting energy states at a molecular level, leading to unsafe effects. Remarkably, thermal effect due to the absorption of RF waves is a better biological manifestation than traditional specific absorption rate (SAR) values...
June 5, 2018: Bioelectromagnetics
Jin Yang, Lijun Sun, Xiushan Fan, Bo Yin, Yiting Kang, Shucheng An, Liang Tang
Diabetic muscle atrophy causes a reduction of skeletal muscle size and strength, which affects normal daily activities. However, pulsed electromagnetic fields (PEMFs) can retard the atrophy of type II fibers (ActRIIB) in denervated muscles. Therefore, the purpose of the present study was to determine whether PEMFs can alleviate streptozotocin (STZ)‑induced diabetic muscle atrophy. To do this, 40 Sprague‑Dawley (SD) rats were randomly divided into four groups (n=10 per group): The normal control group (NC; nondiabetic rats without treatment); the diabetic mellitus group (DM; STZ‑induced rats without treatment); the diabetic insulin‑treated group (DT; diabetic rats on insulin treatment, 6‑8 U/d twice a day for 6 weeks) as a positive control; and the diabetic PEMFs therapy group (DP; diabetic rats with PEMFs exposure treatment, 15 Hz, 1...
July 2018: Molecular Medicine Reports
Omeed Mahrouyan, Øivind Tøien, Frank G Shellock
PURPOSE: The Temperature Logger Implant is a newly developed device that is capable of providing data for animal studies on thermoregulatory function, hibernation, hypothermia, and general health. During research, it may be necessary to conduct a magnetic resonance imaging (MRI) examination on an animal with this device implanted to assess anatomical changes or other conditions. Notably, this new device was specially designed to be unaffected by the electromagnetic fields used for MRI...
May 2018: Journal of Thermal Biology
G P Liney, B Dong, E Weber, R Rai, A Destruel, R Garcia-Alvarez, D J Manton, U Jelen, K Zhang, M Barton, P Keall, S Crozier
This work describes the first imaging studies on a 1.0 Tesla inline MRI-Linac using a dedicated transmit/receive RF body coil that has been designed to be completely radio transparent and provide optimum imaging performance over a large patient opening. A series of experiments was performed on the MRI-Linac to investigate the performance and imaging characteristics of a new dedicated volumetric RF coil: (1) numerical electromagnetic simulations were used to measure transmit efficiency in two patient positions; (2) image quality metrics of signal-to-noise ratio (SNR), ghosting and uniformity were assessed in a large diameter phantom with no radiation beam; (3) radiation induced effects were investigated in both the raw data (k-space) and image sequences acquired with simultaneous irradiation; (4) radiation dose was measured with and without image acquisition; (5) RF heating was studied using an MR-compatible fluoroptic thermometer and; (6) the in vivo image quality and versatility of the coil was demonstrated in normal healthy subjects for both supine and standing positions...
June 25, 2018: Physics in Medicine and Biology
Iram Saleem, Samina Masood, Derek Smith, Wei-Kan Chu
This research project has major applications in the healthcare and biomedical industries. Bacteria reside in human bodies and play an integral role in the mechanism of life. However, their excessive growth or the invasion of similar agents can be dangerous and may cause fatal or incurable diseases. On the other hand, increased exposure to electromagnetic radiation and its impact on health and safety is a common concern to medical science. Some nanostructure materials have interesting properties regarding facilitating or impeding cell growth...
May 24, 2018: MicrobiologyOpen
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