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Sample records for electromagnetic fields enhance

  1. Giant field enhancement in electromagnetic Helmholtz nanoantenna

    NASA Astrophysics Data System (ADS)

    Chevalier, Paul; Bouchon, Patrick; Greffet, Jean-Jacques; Pelouard, Jean-Luc; Haïdar, Riad; Pardo, Fabrice

    2014-11-01

    Inspired by the acoustic Helmholtz resonator, we propose a slit-box electromagnetic nanoantenna able to concentrate the energy of an incident beam into surfaces a thousand times smaller than with a classical lens. This design produces a giant electric field enhancement throughout the slit. The intensity enhancement reaches 104 in the visible range up to 108 in the THz range even with focused beams, thanks to an omnidirectional reception. These properties could target applications requiring extreme light concentration, such as surface-enhanced infrared absorption, nonlinear optics, and biophotonics.

  2. Phenomenological local field enhancement factor distributions around electromagnetic hot spots

    NASA Astrophysics Data System (ADS)

    Le Ru, E. C.; Etchegoin, P. G.

    2009-05-01

    We propose a general phenomenological description of the enhancement factor distribution for surface-enhanced Raman scattering (SERS) and other related phenomena exploiting large local field enhancements at hot spots. This description extends naturally the particular case of a single (fixed) hot spot, and it is expected to be "universal" for many classes of common SERS substrates containing a collection of electromagnetic hot spots with varying geometrical parameters. We further justify it from calculations with generalized Mie theory. The description studied here provides a useful starting point for a qualitative (and semiquantitative) understanding of experimental data and, in particular, the analysis of the statistics of single-molecule SERS events.

  3. Could Radiotherapy Effectiveness Be Enhanced by Electromagnetic Field Treatment?

    PubMed Central

    Francisco, Artacho-Cordón; del Mar, Salinas-Asensio María; Irene, Calvente; Sandra, Ríos-Arrabal; Josefa, León; Elisa, Román-Marinetto; Nicolás, Olea; Isabel, Núñez María

    2013-01-01

    One of the main goals in radiobiology research is to enhance radiotherapy effectiveness without provoking any increase in toxicity. In this context, it has been proposed that electromagnetic fields (EMFs), known to be modulators of proliferation rate, enhancers of apoptosis and inductors of genotoxicity, might control tumor recruitment and, thus, provide therapeutic benefits. Scientific evidence shows that the effects of ionizing radiation on cellular compartments and functions are strengthened by EMF. Although little is known about the potential role of EMFs in radiotherapy (RT), the radiosensitizing effect of EMFs described in the literature could support their use to improve radiation effectiveness. Thus, we hypothesized that EMF exposure might enhance the ionizing radiation effect on tumor cells, improving the effects of RT. The aim of this paper is to review reports of the effects of EMFs in biological systems and their potential therapeutic benefits in radiotherapy. PMID:23867611

  4. Coupled V-structured nano-antenna for electromagnetic field enhancement

    NASA Astrophysics Data System (ADS)

    Chen, Wanli; Zhang, Wanwan; Feng, Yuanming; Lin, Wang

    2017-05-01

    Nano-antennas play an important role in many areas of science and technology. It is desirable to achieve strong electric field enhancement by nano-antenna. In this paper, we simulate a symmetrical V-structured nano-antenna that is used to regulate the electromagnetic fields in the central gap region. We study the effects of structural parameters on the charge distribution and analyze the electric field enhancement factor in the central region of the nano-antenna. Then we use structural coupling methods to strengthen electromagnetic field intensity in the central region. Our results demonstrate that the charge distribution of the nano-antenna can be controlled by regulating the structural parameters, leading to the change of electromagnetic field intensity. In addition, electric field enhancement is achieved by coupling of multiple V structures. The multiple V structure could be used in surface-enhanced Raman scattering due to the electric field enhancement in its central region.

  5. Electromagnetic field enhancement and light localization in deterministic aperiodic nanostructures

    NASA Astrophysics Data System (ADS)

    Gopinath, Ashwin

    The control of light matter interaction in periodic and random media has been investigated in depth during the last few decades, yet structures with controlled degree of disorder such as Deterministic Aperiodic Nano Structures (DANS) have been relatively unexplored. DANS are characterized by non-periodic yet long-range correlated (deterministic) morphologies and can be generated by the mathematical rules of symbolic dynamics and number theory. In this thesis, I have experimentally investigated the unique light transport and localization properties in planar dielectric and metal (plasmonics) DANS. In particular, I have focused on the design, nanofabrication and optical characterization of DANS, formed by arranging metal/dielectric nanoparticles in an aperiodic lattice. This effort is directed towards development of on-chip nanophotonic applications with emphasis on label-free bio-sensing and enhanced light emission. The DANS designed as Surface Enhanced Raman Scattering (SERS) substrate is composed of multi-scale aperiodic nanoparticle arrays fabricated by e-beam lithography and are capable of reproducibly demonstrating enhancement factors as high as ˜107. Further improvement of SERS efficiency is achieved by combining DANS formed by top-down approach with bottom-up reduction of gold nanoparticles, to fabricate novel nanostructures called plasmonic "nano-galaxies" which increases the SERS enhancement factors by 2--3 orders of magnitude while preserving the reproducibility. In this thesis, along with presenting details of fabrication and SERS characterization of these "rationally designed" SERS substrates, I will also present results on using these substrates for detection of DNA nucleobases, as well as reproducible label-free detection of pathogenic bacteria with species specificity. In addition to biochemical detection, the combination of broadband light scattering behavior and the ability for the generation of reproducible high fields in DANS make these

  6. Broadband field enhancement of THz electromagnetic wave by surface-textured micron PVDF cylinders

    NASA Astrophysics Data System (ADS)

    Li, Xinxin; Liu, Xuan; Zhang, Luoning; Zhou, Jing; Liu, Dahe

    2015-07-01

    A cylindrical dimmer system is proposed to realize broadband field enhancement for terahertz (THz) electromagnetic wave. A surface-textured crescent-shaped cylinder is proposed to red-shift the absorption spectrum comparing to the traditional crescent-shaped cylinder based on the concept of spoof surface plasmons. Such cylinders made of ferroelectric polyvinylidene fluoride can realize the electromagnetic wave harvesting at terahertz frequencies with a broadband and huge absorption cross section. Two such cylinders in close proximity could achieve considerable electromagnetic field enhancement and field confinement in the gap, which could be applied in THz molecules detection, toxic chemical sensing, and safety screening and could break the detection binding that limits the molecules <100 nm.

  7. Enhancement of local electromagnetic fields in plasmonic crystals of coaxial metallic nanostructures

    NASA Astrophysics Data System (ADS)

    Iwanaga, Masanobu; Ikeda, Naoki; Sugimoto, Yoshimasa

    2012-01-01

    We have experimentally and numerically examined resonant modes in plasmonic crystals (PlCs) of coaxial metallic nanostructures. Resonance enhancements of local electromagnetic (EM) fields were evaluated quantitatively. We clarified that a local mode induced in the coaxial metallic structure shows the most significant field enhancement. The enhancement factors are comprehensively discussed by comparison with other PlCs, indicating that the coaxial PlC provides a locally intense electric field and EM power flux in the annular slit of 50-nm metallic gaps.

  8. What Are Electromagnetic Fields?

    MedlinePlus

    ... sources of electromagnetic fields Besides natural sources the electromagnetic spectrum also includes fields generated by human-made sources: ... ability to break bonds between molecules. In the electromagnetic spectrum, gamma rays given off by radioactive materials, cosmic ...

  9. Enhancement of Optical Nonlinearities in Composite Media and Structures via Local Fields and Electromagnetic Coupling Effects

    NASA Technical Reports Server (NTRS)

    Smith, David D.

    2002-01-01

    This talk will review the linear and nonlinear optical properties of metal nanoparticles and dielectric microparticles, with an emphasis on local field effects, and whispering gallery modes (WGMs), as well as the conjunction of these two effects for enhanced Raman. In particular, enhanced optical properties that result from electromagnetic coupling effects will be discussed in the context of Mie scattering from concentric spheres and bispheres. Predictions of mode splitting and photonic bandgaps in micro-spheres will be presented and will be shown to be analogous to effects that occur in coupled resonator optical waveguides (CROW). Slow and fast light in SCISSOR / CROW configurations will also be discussed.

  10. Enhancement of Optical Nonlinearities in Composite Media and Structures via Local Fields and Electromagnetic Coupling Effects

    NASA Technical Reports Server (NTRS)

    Smith, David D.

    2002-01-01

    This talk will review the linear and nonlinear optical properties of metal nanoparticles and dielectric microparticles, with an emphasis on local field effects, and whispering gallery modes (WGMs), as well as the conjunction of these two effects for enhanced Raman. In particular, enhanced optical properties that result from electromagnetic coupling effects will be discussed in the context of Mie scattering from concentric spheres and bispheres. Predictions of mode splitting and photonic bandgaps in micro-spheres will be presented and will be shown to be analogous to effects that occur in coupled resonator optical waveguides (CROW). Slow and fast light in SCISSOR / CROW configurations will also be discussed.

  11. Finite Size Effects on the Electromagnetic Field Enhancement from Low-dimensional Silver Nanoshell Dimer Arrays

    NASA Astrophysics Data System (ADS)

    Song, Youlin; Zhao, Ke; Jia, Yu; Hu, Xing; Zhang, Zhenyu

    2009-03-01

    Finite size effects on the optical properties of one-dimensional (1D) and 2D nanoshell dimer arrays are investigated using generalized Mie theory and coupled dipole approximation within the context of surface-enhanced Raman spectroscopy (SERS). It is shown that the huge enhancement in the electromagnetic (EM) field at the center of a given dimer oscillates with the length of the 1D array. For an array of fixed length, the EM enhancement also oscillates along the array, but with a different period. Both types of oscillations can be attributed to the interference of the dynamic dipole fields from different dimers in the array. When generalized to 2D arrays, EM enhancement higher than that of the 1D arrays can be gained with a constant magnitude, a salient feature advantageous to experimental realization of single-molecule SERS. [K. Zhao et al, J. Chem. Phys. 125, 081102 (2005); Y. L. Song et al, accepted by J. Chem. Phys.

  12. Finite size effects on the electromagnetic field enhancement from low-dimensional silver nanoshell dimer arrays

    NASA Astrophysics Data System (ADS)

    Song, Youlin; Zhao, Ke; Jia, Yu; Hu, Xing; Zhang, Zhenyu

    2008-11-01

    Finite size effects on the optical properties of one-dimensional (1D) and two-dimensional (2D) nanoshell dimer arrays are investigated using generalized Mie theory and coupled dipole approximation within the context of surface-enhanced Raman spectroscopy (SERS). It is shown that the huge enhancement in the electromagnetic (EM) field at the center of a given dimer oscillates with the length of the 1D array. For an array of fixed length, the EM enhancement also oscillates along the array, but with a different period. Both types of oscillations can be attributed to the interference of the dynamic dipole fields from different dimers in the array. When generalized to 2D arrays, EM enhancement higher than that of the 1D arrays can be gained with a constant magnitude, a salient feature advantageous to experimental realization of single-molecule SERS.

  13. Electromagnetic field enhancement and spectrum shaping through plasmonically integrated optical vortices.

    PubMed

    Ahn, Wonmi; Boriskina, Svetlana V; Hong, Yan; Reinhard, Björn M

    2012-01-11

    We introduce a new design approach for surface-enhanced Raman spectroscopy (SERS) substrates that is based on molding the optical powerflow through a sequence of coupled nanoscale optical vortices "pinned" to rationally designed plasmonic nanostructures, referred to as Vortex Nanogear Transmissions (VNTs). We fabricated VNTs composed of Au nanodiscs by electron beam lithography on quartz substrates and characterized their near- and far-field responses through combination of computational electromagnetism, and elastic and inelastic scattering spectroscopy. Pronounced dips in the far-field scattering spectra of VNTs provide experimental evidence for an efficient light trapping and circulation within the nanostructures. Furthermore, we demonstrate that VNT integration into periodic arrays of Au nanoparticles facilitates the generation of high E-field enhancements in the VNTs at multiple defined wavelengths. We show that spectrum shaping in nested VNT structures is achieved through an electromagnetic feed-mechanism driven by the coherent multiple scattering in the plasmonic arrays and that this process can be rationally controlled by tuning the array period. The ability to generate high E-field enhancements at predefined locations and frequencies makes nested VNTs interesting substrates for challenging SERS applications.

  14. Enhanced responsiveness to parathyroid hormone and induction of functional differentiation of cultured rabbit costal chondrocytes by a pulsed electromagnetic field.

    PubMed

    Hiraki, Y; Endo, N; Takigawa, M; Asada, A; Takahashi, H; Suzuki, F

    1987-10-22

    Pulsed electromagnetic fields promote healing of delayed united and ununited fractures by triggering a series of events in fibrocartilage. We examined the effects of a pulsed electromagnetic field (recurrent bursts, 15.4 Hz, of shorter pulses of an average of 2 gauss) on rabbit costal chondrocytes in culture. A pulsed electromagnetic field slightly reduced the intracellular cyclic adenosine 3',5'-monophosphate (cAMP) level in the culture. However, it significantly enhanced cAMP accumulation in response to parathyroid hormone (PTH) to 140% of that induced by PTH in its absence, while it did not affect cAMP accumulation in response to prostaglandin E1 or prostaglandin I2. The effect on cAMP accumulation in response to PTH became evident after exposure of the cultures to the pulsed electromagnetic field for 48 h, and was dependent upon the field strength. cAMP accumulation in response to PTH is followed by induction of ornithine decarboxylase, a good marker of differentiated chondrocytes, after PTH treatment for 4 h. Consistent with the enhanced cAMP accumulation, ornithine decarboxylase activity induced by PTH was also increased by the pulsed electromagnetic field to 170% of that in cells not exposed to a pulsed electromagnetic field. Furthermore, stimulation of glycosaminoglycan synthesis, a differentiated phenotype, in response to PTH was significantly enhanced by a pulsed electromagnetic field. Thus, a pulsed electromagnetic field enhanced a series of events in rabbit costal chondrocytes in response to PTH. These findings show that exposure of chondrocytes to a pulsed electromagnetic field resulted in functional differentiation of the cells.

  15. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

  16. Introducing Electromagnetic Field Momentum

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe an elementary way of introducing electromagnetic field momentum. By considering a system of a long solenoid and line charge, the dependence of the field momentum on the electric and magnetic fields can be deduced. I obtain the electromagnetic angular momentum for a point charge and magnetic monopole pair partially through dimensional…

  17. Electromagnetic Field Effects in Explosives

    NASA Astrophysics Data System (ADS)

    Tasker, D. G.; Whitley, V. H.; Lee, R. J.

    2009-12-01

    Present and previous research on the effects of electromagnetic fields on the initiation and detonation of explosives and the electromagnetic properties of explosives are reviewed. Among the topics related to detonating explosives are: enhancement of performance; and control of initiation and growth of reaction. Two series of experiments were performed to determine the effects of 1-T magnetic fields on explosive initiation and growth in the modified gap test and on the propagation of explosively generated plasma into air. The results have implications for the control of reactions in explosives and for the use of electromagnetic particle velocity gauges.

  18. Enhanced skin permeation of naltrexone by pulsed electromagnetic fields in human skin in vitro.

    PubMed

    Krishnan, Gayathri; Edwards, Jeffrey; Chen, Yan; Benson, Heather A E

    2010-06-01

    The aim of the present study was to evaluate the skin permeation of naltrexone (NTX) under the influence of a pulsed electromagnetic field (PEMF). The permeation of NTX across human epidermis and a silicone membrane in vitro was monitored during and after application of the PEMF and compared to passive application. Enhancement ratios of NTX human epidermis permeation by PEMF over passive diffusion, calculated based on the AUC of cumulative NTX permeation to the receptor compartment verses time for 0-4 h, 4-8 h, and over the entire experiment (0-8 h) were 6.52, 5.25, and 5.66, respectively. Observation of the curve indicated an initial enhancement of NTX permeation compared to passive delivery whilst the PEMF was active (0-4 h). This was followed by a secondary phase after termination of PEMF energy (4-8 h) in which there was a steady increase in NTX permeation. No significant enhancement of NTX penetration across silicone membrane occurred with PEMF application in comparison to passively applied NTX. In a preliminary experiment PEMF enhanced the penetration of 10 nm gold nanoparticles through the stratum corneum as visualized by multiphoton microscopy. This suggests that the channels through which the nanoparticles move must be larger than the 10 nm diameter of these rigid particles.

  19. Covariant electromagnetic field lines

    NASA Astrophysics Data System (ADS)

    Hadad, Y.; Cohen, E.; Kaminer, I.; Elitzur, A. C.

    2017-08-01

    Faraday introduced electric field lines as a powerful tool for understanding the electric force, and these field lines are still used today in classrooms and textbooks teaching the basics of electromagnetism within the electrostatic limit. However, despite attempts at generalizing this concept beyond the electrostatic limit, such a fully relativistic field line theory still appears to be missing. In this work, we propose such a theory and define covariant electromagnetic field lines that naturally extend electric field lines to relativistic systems and general electromagnetic fields. We derive a closed-form formula for the field lines curvature in the vicinity of a charge, and show that it is related to the world line of the charge. This demonstrates how the kinematics of a charge can be derived from the geometry of the electromagnetic field lines. Such a theory may also provide new tools in modeling and analyzing electromagnetic phenomena, and may entail new insights regarding long-standing problems such as radiation-reaction and self-force. In particular, the electromagnetic field lines curvature has the attractive property of being non-singular everywhere, thus eliminating all self-field singularities without using renormalization techniques.

  20. Electromagnetic field therapy delays cellular senescence and death by enhancement of the heat shock response.

    PubMed

    Perez, Felipe P; Zhou, Ximing; Morisaki, Jorge; Jurivich, Donald

    2008-04-01

    Hormesis may result when mild repetitive stress increases cellular defense against diverse injuries. This process may also extend in vitro cellular proliferative life span as well as delay and reverse some of the age-dependent changes in both replicative and non-replicative cells. This study evaluated the potential hormetic effect of non-thermal repetitive electromagnetic field shock (REMFS) and its impact on cellular aging and mortality in primary human T lymphocytes and fibroblast cell lines. Unlike previous reports employing electromagnetic radiation, this study used a long wave length, low energy, and non-thermal REMFS (50MHz/0.5W) for various therapeutic regimens. The primary outcomes examined were age-dependent morphological changes in cells over time, cellular death prevention, and stimulation of the heat shock response. REMFS achieved several biological effects that modified the aging process. REMFS extended the total number of population doublings of mouse fibroblasts and contributed to youthful morphology of cells near their replicative lifespan. REMFS also enhanced cellular defenses of human T cells as reflected in lower cell mortality when compared to non-treated T cells. To determine the mechanism of REMFS-induced effects, analysis of the cellular heat shock response revealed Hsp90 release from the heat shock transcription factor (HSF1). Furthermore, REMFS increased HSF1 phosphorylation, enhanced HSF1-DNA binding, and improved Hsp70 expression relative to non-REMFS-treated cells. These results show that non-thermal REMFS activates an anti-aging hormetic effect as well as reduces cell mortality during lethal stress. Because the REMFS configuration employed in this study can potentially be applied to whole body therapy, prospects for translating these data into clinical interventions for Alzheimer's disease and other degenerative conditions with aging are discussed.

  1. Extremely low-frequency electromagnetic fields enhance the survival of newborn neurons in the mouse hippocampus.

    PubMed

    Podda, Maria V; Leone, Lucia; Barbati, Saviana A; Mastrodonato, Alessia; Li Puma, Domenica D; Piacentini, Roberto; Grassi, Claudio

    2014-03-01

    In recent years, much effort has been devoted to identifying stimuli capable of enhancing adult neurogenesis, a process that generates new neurons throughout life, and that appears to be dysfunctional in the senescent brain and in several neuropsychiatric and neurodegenerative diseases. We previously reported that in vivo exposure to extremely low-frequency electromagnetic fields (ELFEFs) promotes the proliferation and neuronal differentiation of hippocampal neural stem cells (NSCs) that functionally integrate in the dentate gyrus. Here, we extended our studies to specifically assess the influence of ELFEFs on hippocampal newborn cell survival, which is a very critical issue in adult neurogenesis regulation. Mice were injected with 5-bromo-2'-deoxyuridine (BrdU) to label newborn cells, and were exposed to ELFEFs 9 days later, when the most dramatic decrease in the number of newly generated neurons occurs. The results showed that ELFEF exposure (3.5 h/day for 6 days) enhanced newborn neuron survival as documented by double staining for BrdU and doublecortin, to identify immature neurons, or NeuN labeling of mature neurons. The effects of ELFEFs were associated with enhanced spatial learning and memory. In an in vitro model of hippocampal NSCs, ELFEFs exerted their pro-survival action by rescuing differentiating neurons from apoptotic cell death. Western immunoblot assay revealed reduced expression of the pro-apoptotic protein Bax, and increased levels of the anti-apoptotic protein Bcl-2, in the hippocampi of ELFEF-exposed mice as well as in ELFEF-exposed NSC cultures, as compared with their sham-exposed counterparts. Our results may have clinical implications for the treatment of impaired neurogenesis associated with brain aging and neurodegenerative diseases.

  2. BEMER Electromagnetic Field Therapy Reduces Cancer Cell Radioresistance by Enhanced ROS Formation and Induced DNA Damage

    PubMed Central

    Artati, Anna; Adamski, Jerzy

    2016-01-01

    Each year more than 450,000 Germans are expected to be diagnosed with cancer subsequently receiving standard multimodal therapies including surgery, chemotherapy and radiotherapy. On top, molecular-targeted agents are increasingly administered. Owing to intrinsic and acquired resistance to these therapeutic approaches, both the better molecular understanding of tumor biology and the consideration of alternative and complementary therapeutic support are warranted and open up broader and novel possibilities for therapy personalization. Particularly the latter is underpinned by the increasing utilization of non-invasive complementary and alternative medicine by the population. One investigated approach is the application of low-dose electromagnetic fields (EMF) to modulate cellular processes. A particular system is the BEMER therapy as a Physical Vascular Therapy for which a normalization of the microcirculation has been demonstrated by a low-frequency, pulsed EMF pattern. Open remains whether this EMF pattern impacts on cancer cell survival upon treatment with radiotherapy, chemotherapy and the molecular-targeted agent Cetuximab inhibiting the epidermal growth factor receptor. Using more physiological, three-dimensional, matrix-based cell culture models and cancer cell lines originating from lung, head and neck, colorectal and pancreas, we show significant changes in distinct intermediates of the glycolysis and tricarboxylic acid cycle pathways and enhanced cancer cell radiosensitization associated with increased DNA double strand break numbers and higher levels of reactive oxygen species upon BEMER treatment relative to controls. Intriguingly, exposure of cells to the BEMER EMF pattern failed to result in sensitization to chemotherapy and Cetuximab. Further studies are necessary to better understand the mechanisms underlying the cellular alterations induced by the BEMER EMF pattern and to clarify the application areas for human disease. PMID:27959944

  3. BEMER Electromagnetic Field Therapy Reduces Cancer Cell Radioresistance by Enhanced ROS Formation and Induced DNA Damage.

    PubMed

    Storch, Katja; Dickreuter, Ellen; Artati, Anna; Adamski, Jerzy; Cordes, Nils

    2016-01-01

    Each year more than 450,000 Germans are expected to be diagnosed with cancer subsequently receiving standard multimodal therapies including surgery, chemotherapy and radiotherapy. On top, molecular-targeted agents are increasingly administered. Owing to intrinsic and acquired resistance to these therapeutic approaches, both the better molecular understanding of tumor biology and the consideration of alternative and complementary therapeutic support are warranted and open up broader and novel possibilities for therapy personalization. Particularly the latter is underpinned by the increasing utilization of non-invasive complementary and alternative medicine by the population. One investigated approach is the application of low-dose electromagnetic fields (EMF) to modulate cellular processes. A particular system is the BEMER therapy as a Physical Vascular Therapy for which a normalization of the microcirculation has been demonstrated by a low-frequency, pulsed EMF pattern. Open remains whether this EMF pattern impacts on cancer cell survival upon treatment with radiotherapy, chemotherapy and the molecular-targeted agent Cetuximab inhibiting the epidermal growth factor receptor. Using more physiological, three-dimensional, matrix-based cell culture models and cancer cell lines originating from lung, head and neck, colorectal and pancreas, we show significant changes in distinct intermediates of the glycolysis and tricarboxylic acid cycle pathways and enhanced cancer cell radiosensitization associated with increased DNA double strand break numbers and higher levels of reactive oxygen species upon BEMER treatment relative to controls. Intriguingly, exposure of cells to the BEMER EMF pattern failed to result in sensitization to chemotherapy and Cetuximab. Further studies are necessary to better understand the mechanisms underlying the cellular alterations induced by the BEMER EMF pattern and to clarify the application areas for human disease.

  4. [Electromagnetic fields hypersensitivity].

    PubMed

    Sobiczewska, Elzbieta; Szmigielski, Stanisław

    2009-01-01

    The development of industry, particularly of new technologies in communication systems, gives rise to the number and diversty of electromagnetic field (EMF) sources in the environment. These sources, including power-frequent, radiofrequent and microwaves, make human life richer, safer and easier. But at the same time, there is growing concern about possible health risks connected with EMF exposure. An increasing number of persons have recently reported on a variety of health problems induced, in their opinion, by exposure to EMF. It is important to note that EMF levels to which these individuals are exposed are generally well below the recommended exposure limits and are certainly far below those known to produce any adverse effects. These persons call themselves "electromagnetic hypersensitivity individuals" And complain about experiencing various types of non-specific symptoms, including dermatological, neurological and vegetative. In the present paper, the problem of electromagnetic hypersensitivity phenomenon is discussed based on the recently published literature.

  5. Tailored Fano resonance and localized electromagnetic field enhancement in Ag gratings

    NASA Astrophysics Data System (ADS)

    Li, Zhaozhu; Klopf, J. Michael; Wang, Lei; Yang, Kaida; Lukaszew, Rosa A.

    2017-03-01

    Metallic gratings can support Fano resonances when illuminated with EM radiation, and their characteristic reflectivity versus incident angle lineshape can be greatly affected by the surrounding dielectric environment and the grating geometry. By using conformal oblique incidence thin film deposition onto an optical grating substrate, it is possible to increase the grating amplitude due to shadowing effects, thereby enabling tailoring of the damping processes and electromagnetic field couplings of the Fano resonances, hence optimizing the associated localized electric field intensity. To investigate these effects we compare the optical reflectivity under resonance excitation in samples prepared by oblique angle deposition (OAD) and under normal deposition (ND) onto the same patterned surfaces. We observe that by applying OAD method, the sample exhibits a deeper and narrower reflectivity dip at resonance than that obtained under ND. This can be explained in terms of a lower damping of Fano resonance on obliquely deposited sample and leads to a stronger localized electric field. This approach opens a fabrication path for applications where tailoring the electromagnetic field induced by Fano resonance can improve the figure of merit of specific device characteristics, e.g. quantum efficiency (QE) in grating-based metallic photocathodes.

  6. Tailored Fano resonance and localized electromagnetic field enhancement in Ag gratings

    PubMed Central

    Li, Zhaozhu; Klopf, J. Michael; Wang, Lei; Yang, Kaida; Lukaszew, Rosa A.

    2017-01-01

    Metallic gratings can support Fano resonances when illuminated with EM radiation, and their characteristic reflectivity versus incident angle lineshape can be greatly affected by the surrounding dielectric environment and the grating geometry. By using conformal oblique incidence thin film deposition onto an optical grating substrate, it is possible to increase the grating amplitude due to shadowing effects, thereby enabling tailoring of the damping processes and electromagnetic field couplings of the Fano resonances, hence optimizing the associated localized electric field intensity. To investigate these effects we compare the optical reflectivity under resonance excitation in samples prepared by oblique angle deposition (OAD) and under normal deposition (ND) onto the same patterned surfaces. We observe that by applying OAD method, the sample exhibits a deeper and narrower reflectivity dip at resonance than that obtained under ND. This can be explained in terms of a lower damping of Fano resonance on obliquely deposited sample and leads to a stronger localized electric field. This approach opens a fabrication path for applications where tailoring the electromagnetic field induced by Fano resonance can improve the figure of merit of specific device characteristics, e.g. quantum efficiency (QE) in grating-based metallic photocathodes. PMID:28290545

  7. Electromagnetic fields enhance chondrogenesis of human adipose-derived stem cells in a chondrogenic microenvironment in vitro.

    PubMed

    Chen, Chung-Hwan; Lin, Yi-Shan; Fu, Yin-Chih; Wang, Chih-Kuang; Wu, Shun-Cheng; Wang, Gwo-Jaw; Eswaramoorthy, Rajalakshmanan; Wang, Yan-Hsiung; Wang, Chau-Zen; Wang, Yao-Hsien; Lin, Sung-Yen; Chang, Je-Ken; Ho, Mei-Ling

    2013-03-01

    We tested the hypothesis that electromagnetic field (EMF) stimulation enhances chondrogenesis in human adipose-derived stem cells (ADSCs) in a chondrogenic microenvironment. A two-dimensional hyaluronan (HA)-coated well (2D-HA) and a three-dimensional pellet culture system (3D-pellet) were used as chondrogenic microenvironments. The ADSCs were cultured in 2D-HA or 3D-pellet, and then treated with clinical-use pulse electromagnetic field (PEMF) or the innovative single-pulse electromagnetic field (SPEMF) stimulation. The cytotoxicity, cell viability, and chondrogenic and osteogenic differentiations were analyzed after PEMF or SPEMF treatment. The modules of PEMF and SPEMF stimulations used in this study did not cause cytotoxicity or alter cell viability in ADSCs. Both PEMF and SPEMF enhanced the chondrogenic gene expression (SOX-9, collagen type II, and aggrecan) of ADSCs cultured in 2D-HA and 3D-pellet. The expressions of bone matrix genes (osteocalcin and collagen type I) of ADSCs were not changed after SPEMF treatment in 2D-HA and 3D-pellet; however, they were enhanced by PEMF treatment. Both PEMF and SPEMF increased the cartilaginous matrix (sulfated glycosaminoglycan) deposition of ADSCs. However, PEMF treatment also increased mineralization of ADSCs, but SPEMF treatment did not. Both PEMF and SPEMF enhanced chondrogenic differentiation of ADSCs cultured in a chondrogenic microenvironment. SPEMF treatment enhanced ADSC chondrogenesis, but not osteogenesis, when the cells were cultured in a chondrogenic microenvironment. However, PEMF enhanced both osteogenesis and chondrogenesis under the same conditions. Thus the combination of a chondrogenic microenvironment with SPEMF stimulation can promote chondrogenic differentiation of ADSCs and may be applicable to articular cartilage tissue engineering.

  8. Electromagnetic Field Penetration Studies

    NASA Technical Reports Server (NTRS)

    Deshpande, M.D.

    2000-01-01

    A numerical method is presented to determine electromagnetic shielding effectiveness of rectangular enclosure with apertures on its wall used for input and output connections, control panels, visual-access windows, ventilation panels, etc. Expressing EM fields in terms of cavity Green's function inside the enclosure and the free space Green's function outside the enclosure, integral equations with aperture tangential electric fields as unknown variables are obtained by enforcing the continuity of tangential electric and magnetic fields across the apertures. Using the Method of Moments, the integral equations are solved for unknown aperture fields. From these aperture fields, the EM field inside a rectangular enclosure due to external electromagnetic sources are determined. Numerical results on electric field shielding of a rectangular cavity with a thin rectangular slot obtained using the present method are compared with the results obtained using simple transmission line technique for code validation. The present technique is applied to determine field penetration inside a Boeing-757 by approximating its passenger cabin as a rectangular cavity filled with a homogeneous medium and its passenger windows by rectangular apertures. Preliminary results for, two windows, one on each side of fuselage were considered. Numerical results for Boeing-757 at frequencies 26 MHz, 171-175 MHz, and 428-432 MHz are presented.

  9. Elucidating the sole contribution from electromagnetic near-fields in plasmon-enhanced Cu2O photocathodes

    DOE PAGES

    DuChene, Joseph S.; Williams, Benjamin P.; Johnston-Peck, Aaron C.; ...

    2015-11-05

    Despite many promising reports of plasmon-enhanced photocatalysis, the inability to identify the individual contributions from multiple enhancement mechanisms has delayed the development of general design rules for engineering efficient plasmonic photocatalysts. Herein, we construct a plasmonic photocathode comprised of Au@SiO2 (core@shell) nanoparticles embedded within a Cu2O nanowire network to exclusively examine the contribution from one such mechanism: electromagnetic near-field enhancement. The influence of the local electromagnetic field intensity is correlated with the overall light-harvesting efficiency of the device through variation of the SiO2 shell thickness (5—22 nm) to systematically tailor the distance between the plasmonic Au nanoparticles and the Cu2Omore » nanowires. A three-fold increase in device photocurrent is achieved upon integrating the Au@SiO2 nanoparticles into the Cu2O nanowire network, further enabling a ~40% reduction in semiconductor film thickness while maintaining photocathode performance. Photoelectrochemical results are further correlated with photoluminescence studies and optical simulations to confirm that the near-field enhancement is the sole mechanism responsible for increased light absorption in the plasmonic photocathode.« less

  10. Proca and electromagnetic fields

    SciTech Connect

    Hillion, P.; Quinnerz, S.

    1986-07-01

    In the framework of the proper orthochronous Lorentz group, the old connection is revived between the electromagnetic field characterized by a self-dual tensor and a traceless second-rank spinor obeying the Proca equation. The relationship between this spinor and the Hertz potential also considered as a self-dual tensor is emphasized. The extension of this formalism to meet the covariance under the full Lorentz group is also discussed.

  11. Carter separable electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Lynden-Bell, D.

    2000-02-01

    The purely electromagnetic analogue in flat space of Kerr's metric in general relativity is only rarely considered. Here we carry out in flat space a programme similar to Carter's investigation of metrics in general relativity in which the motion of a charged particle is separable. We concentrate on the separability of the motion (be it classical, relativistic or quantum) of a charged particle in electromagnetic fields that lie in planes through an axis of symmetry. In cylindrical polar coordinates (t,R,φ,z) the four-vector potential takes the form [formmu2] is the unit toroidal vector. The forms of the functions Φ(R,z) and A(R,z) are sought that allow separable motion. This occurs for relativistic motion only when AR,Φ and A2-Φ2 are all of the separable form ζ(λ)-η(μ)]/(λ-μ), where ζ and η are arbitrary functions, and λ and μ are spheroidal coordinates or degenerations thereof. The special forms of A and Φ that allow this are deduced. They include the Kerr metric analogue, with E+iB=-∇{q[(r-ia).(r-ia)]-1/2}. Rather more general electromagnetic fields allow separation when the motion is non-relativistic. The investigation is extended to fields that lie in parallel planes. Connections to Larmor's theorem are remarked upon.

  12. Geometry-dependent plasmon resonances of metallic nanostructures for enhancement of localized electromagnetic fields around the nanostructures

    NASA Astrophysics Data System (ADS)

    Gerhold, Michael; Dhawan, Anuj; Vo-Dinh, Tuan

    2008-02-01

    This paper describes theoretical and experimental evaluations of electromagnetic fields around metallic nanostructures, such as nanorods, nano-pillars, and a collection of nanorods separated by nano-scale distances. Nanostructures having different sizes and shapes were evaluated. The spacing between nanorods and elliptical nanopillars was varied such that the effect of nanoparticle spacing on the electromagnetic fields in the regions between the nanostructures could be studied. Gold was the metal employed in our work as it demonstrates substantial plasmon excitation and is chemically stable. Calculations of the electromagnetic fields in the vicinity of the different metallic nanostructures were made by employing Finite Difference Time Domain (FDTD). Refractive index of the media surrounding the nanostructures was varied for these calculations. These calculations were carried out at different wavelengths in the visible and near-infrared spectral regimes. In order to fabricate these nanostructures on silica substrates, focused ion beam (FIB) milling was employed. These structures were fabricated on gold-coated planar silica and mica substrates and tips of four mode and multimode optical fibers. In our experimental evaluations of the different metallic nanostructures, surface enhanced Raman scattering (SERS) signals from the different metallic nanostructures were obtained and were correlated to the spacing distance between the different metallic nanostructures.

  13. Electromagnetic Fields and Cancer

    MedlinePlus

    ... are in the ionizing radiation part of the electromagnetic spectrum and can damage DNA or cells directly. Low- ... in the non-ionizing radiation part of the electromagnetic spectrum and are not known to damage DNA or ...

  14. Interactions between electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Schwan, H. P.

    1985-02-01

    We applied for this grant to support a workshop at Erice, Italy. This workshop has been commonly called Erice School and the main subject of this workshop is the interaction of electromagnetic fields with biological cells and molecules. The grant from ONR enabled us to invite American scientists to participants in this workshop and deliver scientific papers. The duration of the Erice School was ten days. Therefore, we had sufficient time to discuss the problems of electromagnetic radiations. Vigorous discussions took place during official sessions and during private conversations. The participants of this workshop are mostly those who have been active in the research on bioelectromagnetics, but there are some numbers of speakers who discussed the basic electrical and magnetic properties of polyelectrolytes, biological membranes and tissue. The workshop was unique in that there were participants with a variety of training backgrounds. This enabled us to exchange the information between applied scientists and basic scientists. Also, active exchanges of opinions took place between biological scientists and physical scientists.

  15. Extremely low frequency electromagnetic field enhances human keratinocyte cell growth and decreases proinflammatory chemokine production.

    PubMed

    Vianale, G; Reale, M; Amerio, P; Stefanachi, M; Di Luzio, S; Muraro, R

    2008-06-01

    Proliferation and differentiation of keratinocytes are central processes in tissue regeneration after injury. Chemokines, produced by a wide range of cell types including keratinocytes, play a regulatory role in inflammatory skin diseases. Several studies have shown that an electromagnetic field (EMF) can influence both inflammatory processes and repair mechanisms including wound healing on different tissue models. To elucidate the effect of extremely low frequency EMF (ELF-EMF) on keratinocyte proliferation and production of chemokines [RANTES, monocyte chemoattractant protein (MCP)-1, macrophage inflammatory protein (MIP)-1 alpha and interleukin (IL)-8] in order to evaluate a potential therapeutic use of magnetic fields. The human keratinocyte cell line HaCaT was exposed at 1 mT, 50 Hz for different lengths of time and compared with unexposed control cells. Cell growth and viability were evaluated at different exposure times by cell count and trypan blue exclusion. Chemokine production and expression were analysed by enzyme-linked immunosorbent assay (ELISA) and by real-time polymerase chain reaction. Total NF-kappaB p65 was quantified by ELISA. Significantly increased growth rates were observed after 48 h of EMF exposure as compared with control cells, while no difference in cell viabilities were detected. Gene expression and release of RANTES, MCP-1, MIP-1 alpha and IL-8 were significantly reduced after 72 h of exposure. NF-kappaB levels became almost undetectable after only 1 h of EMF exposure, and were inversely correlated with cell density. Our results show that ELF-EMF modulates chemokine production and keratinocyte growth through inhibition of the NF-kappaB signalling pathway and thus may inhibit inflammatory processes. ELF-EMF could represent an additional therapeutic approach in the treatment of skin injury.

  16. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, R.D.; Deis, G.A.

    1992-03-24

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles. 14 figs.

  17. Tunability enhanced electromagnetic wiggler

    DOEpatents

    Schlueter, Ross D.; Deis, Gary A.

    1992-01-01

    The invention discloses a wiggler used in synchrotron radiation sources and free electron lasers, where each pole is surrounded by at least two electromagnetic coils. The electromagnetic coils are energized with different amounts of current to provide a wide tunable range of the on-axis magnetic flux density, while preventing magnetic saturation of the poles.

  18. Pulsed Electromagnetic Fields Enhance Bone Morphogenetic Protein-2 Dependent-Bone Regeneration.

    PubMed

    Yang, Hoon Joo; Kim, Ri Youn; Hwang, Soon Jung

    2015-10-01

    The use of recombinant human bone morphogenetic protein-2 (rhBMP-2) for the purpose of promoting bone regeneration is emerging; however, the high dose of rhBMP-2 required in humans is accompanied by several limitations, including bone resorption and swelling. To reduce the dose of rhBMP-2 required, the applicability of pulsed electromagnetic fields (PEMF) was evaluated using a rat calvarial defect model. After creating an 8-mm-diameter calvarial bone defect, a collagen sponge soaked in different concentrations (0, 2.5, 5, 10 μg) of rhBMP-2 was implanted at the defect area. One week after surgery, PEMF was applied for 8 h/day over 5 days in an experimental group of animals (n = 28) using a width of 12 μs, a pulse frequency of 60 Hz, and a magnetic intensity of 10 G. Animals were sacrificed 4 weeks after surgery and assessed by microcomputed tomography and histological and immunohistochemical analyses. In the absence of application of PEMF, bone volume, bone mineral density, trabecular thickness, trabecular number, and trabecular separation, all showed statistically significant differences, depending on the concentration of rhBMP-2 utilized (p < 0.001). PEMF accelerated bone regeneration in the groups that received 0, 2.5, and 5 μg rhBMP-2 (p < 0.05). In contrast, administration of 10 μg rhBMP-2 resulted in no additive effect on bone regeneration in combination with PEMF. Groups receiving no rhBMP-2 showed distinct bone regeneration in the central zone of the bone defect when treated with PEMF, whereas they failed to bridge the defect space without PEMF. Among the groups without PEMF, soft tissue infiltrations from the outer surface on the skin side were common. Among groups with PEMF, the groups receiving 5 and 10 μg rhBMP-2 displayed denser bone with significantly reduced dead spaces. The application of PEMF did not result in an accelerated effect on bone regeneration in groups treated with 10 μg rhBMP-2. Therefore, our data

  19. Manipulation of electromagnetic fields with plasmonic nanostructures: Nonlinear frequency mixing, optical manipulation, enhancement and suppression of photocurrent in a silicon photodiode, and surface-enhanced spectroscopy

    NASA Astrophysics Data System (ADS)

    Grady, Nathaniel K.

    Metallic nanostructures are one of the most versatile tools available for manipulating light at the nanoscale. These nanostructures support surface plasmons, which are collective excitations of the conduction electrons that can exist as propagating waves at a metallic interface or as localized excitations of a nanoparticle or nanostructure. Plasmonic structures can efficiently couple energy from freely propagating electromagnetic waves to localized electromagnetic fields and vice-versa, essentially acting as an optical antenna. As a result, the intensity of the local fields around and inside the nanostructure are strongly enhanced compared to the incident radiation. In this thesis, this ability to manipulate electromagnetic fields on the nanoscale is employed to control a wide range of optical phenomena. These studies are performed using structures based on metallic nanoshells, which consist of a thin Au shell coating a silica nanosphere. To investigate the parameters controlling the plasmonic response of metallic nanoshells, two changes to the nanoshell composition are studied: (1) the Au shell is replaced with Cu which has interband transitions that strongly influence the plasmon resonance, and (2) the silica core is replaced by a semiconducting Cu 2O core which has a significantly higher dielectric constant and non-trivial absorbance. The focusing of electromagnetic energy into intense local fields by plasmonic nanostructures is then directly investigated by profiling the nanoshell near field using a Raman-based molecular ruler. Next, plasmons supported by Au nanoshells are used to control the fluorescence of near-infrared fluorophores placed at controlled distances from the nanoshell surface. In this context, the analogy of an optical antenna is very relevant: the enhanced field at the surface of the nanoshell increases the absorption of light by the fluorophore, or equivalently couples propagating electromagnetic waves into a localized receiver, while the

  20. Coherent hybrid electromagnetic field imaging

    DOEpatents

    Cooke, Bradly J.; Guenther, David C.

    2008-08-26

    An apparatus and corresponding method for coherent hybrid electromagnetic field imaging of a target, where an energy source is used to generate a propagating electromagnetic beam, an electromagnetic beam splitting means to split the beam into two or more coherently matched beams of about equal amplitude, and where the spatial and temporal self-coherence between each two or more coherently matched beams is preserved. Two or more differential modulation means are employed to modulate each two or more coherently matched beams with a time-varying polarization, frequency, phase, and amplitude signal. An electromagnetic beam combining means is used to coherently combine said two or more coherently matched beams into a coherent electromagnetic beam. One or more electromagnetic beam controlling means are used for collimating, guiding, or focusing the coherent electromagnetic beam. One or more apertures are used for transmitting and receiving the coherent electromagnetic beam to and from the target. A receiver is used that is capable of square-law detection of the coherent electromagnetic beam. A waveform generator is used that is capable of generation and control of time-varying polarization, frequency, phase, or amplitude modulation waveforms and sequences. A means of synchronizing time varying waveform is used between the energy source and the receiver. Finally, a means of displaying the images created by the interaction of the coherent electromagnetic beam with target is employed.

  1. Nonlinear electromagnetic fields and symmetries

    NASA Astrophysics Data System (ADS)

    Barjašić, Irena; Gulin, Luka; Smolić, Ivica

    2017-06-01

    We extend the classical results on the symmetry inheritance of the canonical electromagnetic fields, described by the Maxwell's Lagrangian, to a much wider class of models, which include those of the Born-Infeld, power Maxwell and the Euler-Heisenberg type. Symmetry inheriting fields allow the introduction of electromagnetic scalar potentials and these are proven to be constant on the Killing horizons. Finally, using the relations obtained along the analysis, we generalize and simplify the recent proof for the symmetry inheritance of the 3-dimensional case, as well as give the first constraint for the higher dimensional electromagnetic fields.

  2. Understanding possible electromagnetic counterparts to loud gravitational wave events: Binary black hole effects on electromagnetic fields

    SciTech Connect

    Palenzuela, Carlos; Lehner, Luis; Yoshida, Shin

    2010-04-15

    In addition to producing loud gravitational waves, the dynamics of a binary black hole system could induce emission of electromagnetic radiation by affecting the behavior of plasmas and electromagnetic fields in their vicinity. We study how the electromagnetic fields are affected by a pair of orbiting black holes through the merger. In particular, we show how the binary's dynamics induce a variability in possible electromagnetically induced emissions as well as an enhancement of electromagnetic fields during the late-merge and merger epochs. These time dependent features will likely leave their imprint in processes generating detectable emissions and can be exploited in the detection of electromagnetic counterparts of gravitational waves.

  3. Extremely low-frequency electromagnetic fields enhance the proliferation and differentiation of neural progenitor cells cultured from ischemic brains.

    PubMed

    Cheng, Yannan; Dai, Yiqin; Zhu, Ximin; Xu, Haochen; Cai, Ping; Xia, Ruohong; Mao, Lizhen; Zhao, Bing-Qiao; Fan, Wenying

    2015-10-21

    In the mammalian brain, neurogenesis persists throughout the embryonic period and adulthood in the subventricular zone of the lateral ventricle and the granular zone (dentate gyrus) of the hippocampus. Newborn neural progenitor cells (NPCs) in the two regions play a critical role in structural and functional plasticity and neural regeneration after brain injury. Previous studies have reported that extremely low-frequency electromagnetic fields (ELF-EMF) could promote osteogenesis, angiogenesis, and cardiac stem cells' differentiation, which indicates that ELF-EMF might be an effective tool for regenerative therapy. The present studies were carried out to examine the effects of ELF-EMF on hippocampal NPCs cultured from embryonic and adult ischemic brains. We found that exposure to ELF-EMF (50 Hz, 0.4 mT) significantly enhanced the proliferation capability both in embryonic NPCs and in ischemic NPCs. Neuronal differentiation was also enhanced after 7 days of cumulative ELF-EMF exposure, whereas glial differentiation was not influenced markedly. The expression of phosphorylated Akt increased during the proliferation process when ischemic NPCs were exposed to ELF-EMF. However, blockage of the Akt pathway abolished the ELF-EMF-induced proliferation of ischemic NPCs. These data show that ELF-EMF promotes neurogenesis of ischemic NPCs and suggest that this effect may occur through the Akt pathway.Video abstract, Supplemental Digital Content 1, http://links.lww.com/WNR/A347.

  4. Electromagnetic fields and public health.

    PubMed Central

    Aldrich, T E; Easterly, C E

    1987-01-01

    A review of the literature is provided for the topic of health-related research and power frequency electromagnetic fields. Minimal evidence for concern is present on the basis of animal and plant research. General observation would accord with the implication that there is no single and manifest health effect as the result of exposure to these fields. There are persistent indications, however, that these fields have biologic activity, and consequently, there may be a deleterious component to their action, possibly in the presence of other factors. Power frequency electromagnetic field exposures are essentially ubiquitous in modern society, and their implications in the larger perspective of public health are unclear at this time. Electromagnetic fields represent a methodological obstacle for epidemiologic studies and a quandary for risk assessment; there is need for more data. PMID:3319560

  5. X-ray-induced apoptosis of BEL-7402 cell line enhanced by extremely low frequency electromagnetic field in vitro.

    PubMed

    Jian, Wen; Wei, Zhao; Zhiqiang, Cheng; Zheng, Fang

    2009-02-01

    This study was designed to test whether extremely low frequency electromagnetic field (ELF-EMF) could enhance the apoptosis-induction effect of X-ray radiotherapy on liver cancer cell line BEL-7402 in vitro. EMF exposure was performed inside an energized solenoid coil. X-ray irradiation was performed using a linear accelerator. Apoptosis rates of BEL-7402 cells were analyzed using Annexin V-Fit Apoptosis Detection kit. Apoptosis rates of EMF group and sham EMF group were compared when combined with X-ray irradiation. Our results suggested that the apoptosis rate of BEL-7402 cells exposed to low doses of X-ray irradiation could be significantly increased by EMF. More EMF exposures obtain significantly higher apoptosis rates than fewer EMF exposures when combined with 2 Gy X-ray irradiation. These findings suggested that ELF-EMF could augment the cell apoptosis effects of low doses of X-ray irradiation on BEL-7402 cells in a synergistic and cumulative way.

  6. Enhanced Microfluidic Electromagnetic Measurements

    NASA Technical Reports Server (NTRS)

    Giovangrandi, Laurent (Inventor); Ricco, Antonio J. (Inventor); Kovacs, Gregory (Inventor)

    2015-01-01

    Techniques for enhanced microfluidic impedance spectroscopy include causing a core fluid to flow into a channel between two sheath flows of one or more sheath fluids different from the core fluid. Flow in the channel is laminar. A dielectric constant of a fluid constituting either sheath flow is much less than a dielectric constant of the core fluid. Electrical impedance is measured in the channel between at least a first pair of electrodes. In some embodiments, enhanced optical measurements include causing a core fluid to flow into a channel between two sheath flows of one or more sheath fluids different from the core fluid. An optical index of refraction of a fluid constituting either sheath flow is much less than an optical index of refraction of the core fluid. An optical property is measured in the channel.

  7. Medical applications of electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Lai, Henry C.; Singh, Narendra P.

    2010-04-01

    In this article, we describe two possible applications of low-intensity non-ionizing electromagnetic fields (EMF) for the treatment of malaria and cancer, respectively. In malaria treatment, a low-intensity extremely-low frequency magnetic field can be used to induce vibration of hemozoin, a super-paramagnetic polymer particle, inside malaria parasites. This disturbance could cause free radical and mechanical damages leading to the death of the parasite. This concept has been tested in vitro on malaria parasites and found to be effective. This may provide a low cost effective treatment for malaria infection in humans. The rationale for cancer treatment using low-intensity EMF is based on two concepts that have been well established in the literature: (1) low-intensity non-thermal EMF enhances cytotoxic free radicals via the iron-mediated Fenton reaction; and (2) cancer cells have higher amounts of free iron, thus are more susceptible to the cytotoxic effects of EMF. Since normal cells contain minimal amount of free iron, the effect would be selectively targeting cancer cells. Thus, no adverse side effect would be expected as in traditional chemotherapy and radiation therapy. This concept has also been tested on human cancer cell and normal cells in vitro and proved to be feasible.

  8. Near-field electromagnetic wave scattering from random self-affine fractal metal surfaces: Spectral dependence of local field enhancements and their statistics in connection with surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Sánchez-Gil, José A.; García-Ramos, José V.; Méndez, Eugenio R.

    2000-10-01

    By means of rigorous numerical simulation calculations based on the Green's theorem integral equation formulation, we study the near electromagnetic field in the vicinity of very rough, one-dimensional self-affine fractal surfaces of Ag, Au, and Cu (for both vacuum and water propagating media) illuminated by a p-polarized field. Strongly localized enhanced optical excitations (hot spots) are found, with electric field intensity enhancements of close to 4 orders of magnitude and widths below a tenth of the incoming wavelength. These effects are produced by the roughness-induced surface-plasmon polariton excitation. We study the characteristics of these optical excitations as well as other properties of the surface electromagnetic field, such as its statistics (probability density function, average, and fluctuations), and their dependence on the excitation spectrum (in the visible and near-infrared regions). Our study is relevant to the use of self-affine fractals as surface-enhanced Raman scattering substrates, where large local and average field enhancements are desired.

  9. String theory in electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Ambjørn, Jan; Makeenko, Yuri M.; Semenoff, Gordon W.; Szabo, Richard J.

    2003-02-01

    A review of various aspects of superstrings in background electromagnetic fields is presented. Topics covered include the Born-Infeld action, spectrum of open strings in background gauge fields, the Schwinger mechanism, finite-temperature formalism and Hagedorn behaviour in external fields, Debye screening, D-brane scattering, thermodynamics of D-branes, and noncommutative field and string theories on D-branes. The electric field instabilities are emphasized throughout and contrasted with the case of magnetic fields. A new derivation of the velocity-dependent potential between moving D-branes is presented, as is a new result for the velocity corrections to the one-loop thermal effective potential.

  10. Explanations, Education, and Electromagnetic Fields.

    ERIC Educational Resources Information Center

    Friedman, Sharon M.

    Explaining complex scientific and environmental subjects in the mass media is difficult to do, particularly under such constraints as short deadlines and lack of space or time. When a scientific controversy and human health risk are involved, this becomes an even harder task to accomplish. The subject of electromagnetic fields (EMF) involves…

  11. Health hazards and electromagnetic fields.

    PubMed

    Saunders, T

    2003-11-01

    Biological rhythms, physical wellbeing and mental states are dependent on our electrical brainwave system interacting with the extremely weak electromagnetic fields generated by the Earth's telluric and Cosmic radiations. In a single generation, since the evolution of humankind over millions of years, we are exposed to a wide range of powerful, artificially generated electromagnetic radiation which adversely affects the subtle balance in nature's energy fields and has become the source of so-called 'diseases of civilization'. This also includes electromagnetic sensitivity. Generally, there is a lack of awareness and understanding of the impact electromagnetic fields can have upon health and wellbeing.Our ancestors were acutely aware that certain locations, were perceived to have a positive energy field which was beneficial to health and vitality. Over time, these areas are now referred to as sacred sites for spiritual ceremony and as healing centres. In contrast, there are other geographical locations that can have a negative effect upon health and these are known as geopathic stress zones. It is believed that such zones can interfere with the brain's normal function that inhibits the release of melatonin and other endocrine secretions needed to replenish the immune system. Geopathic stress can affect animals and plant life as well as human beings and significantly contributes to sick building syndrome (SBS). Whilst there is an increasing body of opinion amongst eminent researchers and scientists who are addressing these issues, the establishment professions are slow to change. However, very gradually, modern allopathic medicine and attitudes are beginning to recognise the extraordinary wisdom and efficacy of ancient traditions such as acupuncture, light, colour and other therapies based on the understanding and treatment of the interaction of a person's electromagnetic subtle body and the immediate environment. These and many other 'complementary' therapies may

  12. Surpassingly competitive electromagnetic field enhancement at the silica/silver interface for selective intracellular surface enhanced Raman scattering detection.

    PubMed

    Radziuk, Darya; Möhwald, Helmuth

    2015-03-24

    A thin plasmonic nanofilm is formed by preformed silver nanoparticles (30 nm) in the matrix of poly(vinyl alcohol) adsorbed on silica microparticles (1.5 μm) (SiO2@Ag-PVA). By applying finite element method (FEM) analysis the surface enhanced Raman spectroscopy (SERS) enhancement factors (EFs) can reach 10(5) with higher values from 10(9) to 10(11) in the silver layer of 5 nm thickness. Nanoparticles in the SiO2@Ag-PVA nanofilm need at least 15 nm radius to exhibit SERS EFs greater than 10(7). High values of this enhancement at the silver/silica interface of spherical geometry can be reached faster by using a 532 nm compared to 785 nm excitation wavelength. By this approach different SERS spectral features can be distinguished between live fibroblasts with spread ("healthy" state) or round ("unhealthy" state) shapes. Characteristic features of secondary protein structures, detection of different acidic conditions and cholesterol with at least a 3-fold higher sensitivity are examined. Moreover, a greater amount of glucose (glucogen) and also tyrosine can be monitored in real time. This is important in identification of higher risk of diabetes as well as in several genetic metabolic disorders (e.g., phenylketonuria, tyrosinaemia type II and tyrosinosis).

  13. Elucidating the sole contribution from electromagnetic near-fields in plasmon-enhanced Cu2O photocathodes

    SciTech Connect

    DuChene, Joseph S.; Williams, Benjamin P.; Johnston-Peck, Aaron C.; Qiu, Jingjing; Gomes, Mathieu; Amilhau, Maxime; Bejleri, Donald; Weng, Jiena; Su, Dong; Huo, Fengwei; Stach, Eric A.; Wei, Wei David

    2015-11-05

    Despite many promising reports of plasmon-enhanced photocatalysis, the inability to identify the individual contributions from multiple enhancement mechanisms has delayed the development of general design rules for engineering efficient plasmonic photocatalysts. Herein, we construct a plasmonic photocathode comprised of Au@SiO2 (core@shell) nanoparticles embedded within a Cu2O nanowire network to exclusively examine the contribution from one such mechanism: electromagnetic near-field enhancement. The influence of the local electromagnetic field intensity is correlated with the overall light-harvesting efficiency of the device through variation of the SiO2 shell thickness (5—22 nm) to systematically tailor the distance between the plasmonic Au nanoparticles and the Cu2O nanowires. A three-fold increase in device photocurrent is achieved upon integrating the Au@SiO2 nanoparticles into the Cu2O nanowire network, further enabling a ~40% reduction in semiconductor film thickness while maintaining photocathode performance. Photoelectrochemical results are further correlated with photoluminescence studies and optical simulations to confirm that the near-field enhancement is the sole mechanism responsible for increased light absorption in the plasmonic photocathode.

  14. The enhanced effects of antibiotics irradiated of extremely high frequency electromagnetic field on Escherichia coli growth properties.

    PubMed

    Torgomyan, Heghine; Trchounian, Armen

    2015-01-01

    The effects of extremely high frequency electromagnetic irradiation and antibiotics on Escherichia coli can create new opportunities for applications in different areas—medicine, agriculture, and food industry. Previously was shown that irradiated bacterial sensitivity against antibiotics was changed. In this work, it was presented the results that irradiation of antibiotics and then adding into growth medium was more effective compared with non-irradiated antibiotics bactericidal action. The selected antibiotics (tetracycline, kanamycin, chloramphenicol, and ceftriaxone) were from different groups. Antibiotics irradiation was performed with low intensity 53 GHz frequency during 1 h. The E. coli growth properties—lag-phase duration and specific growth rate—were markedly changed. Enhanced bacterial sensitivity to irradiated antibiotics is similar to the effects of antibiotics of higher concentrations.

  15. Extremely low frequency electromagnetic fields

    SciTech Connect

    Wilson, B.W. . Chemical Sciences Dept.); Stevens, R.G. ); Anderson, L.E. . Life Sciences Center)

    1990-01-01

    The authors focus on that which seems to be the central scientific issue emerging from current ELF research in epidemiology and in the laboratory; namely, can ELF electromagnetic fields interact with biological systems in such a way as to increase cancer risk The authors examine how cancer risk might be related to two reproducible biological effects of ELF exposure: effects on the pineal gland and circadian biology, and effects on calcium homeostasis in cells. Because they are concerned with the possible biological mechanisms of carcinogenesis, epidemiological studies are only briefly reviewed.

  16. 78 FR 33633 - Human Exposure to Radiofrequency Electromagnetic Fields

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-04

    ... to Radiofrequency Electromagnetic Fields; Reassessment of Exposure to Radiofrequency Electromagnetic..., and 95 Human Exposure to Radiofrequency Electromagnetic Fields AGENCY: Federal Communications... electromagnetic fields. More specifically, the Commission clarifies evaluation procedures and references...

  17. Quantization of Electromagnetic Fields in Cavities

    NASA Technical Reports Server (NTRS)

    Kakazu, Kiyotaka; Oshiro, Kazunori

    1996-01-01

    A quantization procedure for the electromagnetic field in a rectangular cavity with perfect conductor walls is presented, where a decomposition formula of the field plays an essential role. All vector mode functions are obtained by using the decomposition. After expanding the field in terms of the vector mode functions, we get the quantized electromagnetic Hamiltonian.

  18. Electromagnetic fields in cased borehole

    SciTech Connect

    Lee, Ki Ha; Kim, Hee Joon; Uchida, Toshihiro

    2001-07-20

    Borehole electromagnetic (EM) measurements, using fiberglass-cased boreholes, have proven useful in oil field reservoir characterization and process monitoring (Wilt et al., 1995). It has been presumed that these measurements would be impossible in steel-cased wells due to the very large EM attenuation and phase shifts. Recent laboratory and field studies have indicated that detection of EM signals through steel casing should be possible at low frequencies, and that these data provide a reasonable conductivity image at a useful scale. Thus, we see an increased application of this technique to mature oilfields, and an immediate extension to geothermal industry as well. Along with the field experiments numerical model studies have been carried out for analyzing the effect of steel casing to the EM fields. The model used to be an infinitely long uniform casing embedded in a homogeneous whole space. Nevertheless, the results indicated that the formation signal could be accurately recovered if the casing characteristics were independently known (Becker et al., 1998; Lee el al., 1998). Real steel-cased wells are much more complex than the simple laboratory models used in work to date. The purpose of this study is to develop efficient numerical methods for analyzing EM fields in realistic settings, and to evaluate the potential application of EM technologies to cross-borehole and single-hole environment for reservoir characterization and monitoring.

  19. 50-Hz extremely low frequency electromagnetic fields enhance cell proliferation and DNA damage: possible involvement of a redox mechanism.

    PubMed

    Wolf, Federica I; Torsello, Angela; Tedesco, Beatrice; Fasanella, Silvia; Boninsegna, Alma; D'Ascenzo, Marcello; Grassi, Claudio; Azzena, Gian Battista; Cittadini, Achille

    2005-03-22

    HL-60 leukemia cells, Rat-1 fibroblasts and WI-38 diploid fibroblasts were exposed for 24-72 h to 0.5-1.0-mT 50-Hz extremely low frequency electromagnetic field (ELF-EMF). This treatment induced a dose-dependent increase in the proliferation rate of all cell types, namely about 30% increase of cell proliferation after 72-h exposure to 1.0 mT. This was accompanied by increased percentage of cells in the S-phase after 12- and 48-h exposure. The ability of ELF-EMF to induce DNA damage was also investigated by measuring DNA strand breaks. A dose-dependent increase in DNA damage was observed in all cell lines, with two peaks occurring at 24 and 72 h. A similar pattern of DNA damage was observed by measuring formation of 8-OHdG adducts. The effects of ELF-EMF on cell proliferation and DNA damage were prevented by pretreatment of cells with an antioxidant like alpha-tocopherol, suggesting that redox reactions were involved. Accordingly, Rat-1 fibroblasts that had been exposed to ELF-EMF for 3 or 24 h exhibited a significant increase in dichlorofluorescein-detectable reactive oxygen species, which was blunted by alpha-tocopherol pretreatment. Cells exposed to ELF-EMF and examined as early as 6 h after treatment initiation also exhibited modifications of NF kappa B-related proteins (p65-p50 and I kappa B alpha), which were suggestive of increased formation of p65-p50 or p65-p65 active forms, a process usually attributed to redox reactions. These results suggest that ELF-EMF influence proliferation and DNA damage in both normal and tumor cells through the action of free radical species. This information may be of value for appraising the pathophysiologic consequences of an exposure to ELF-EMF.

  20. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

    Eissenberg, David M.; Haynes, Howard D.; Casada, Donald A.

    1993-01-01

    One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

  1. Noninvasive valve monitor using alternating electromagnetic field

    DOEpatents

    Eissenberg, D.M.; Haynes, H.D.; Casada, D.A.

    1993-03-16

    One or more electrical coils are carefully located on the outside of a valve body. An alternating current passing through the coil(s) results in an alternating electromagnetic field being transmitted into the valve body and valve internals. The electromagnetic field varies in intensity and polarity in the valve. As the position of a valve internal part is changed, the electromagnetic field throughout the valve body and its internals is altered. A passive receiver coil carefully located on the outside of the valve body detects the intensity of the electromagnetic field at that location as an induced electrical voltage in the coil. With the change in position of the valve internal part, there is a corresponding change in the induced voltage as a result of the alteration in the alternating electromagnetic field at that location. Changes in the voltage provide an indication of the position and motion of valve internals.

  2. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1997-06-24

    An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 26 figs.

  3. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1998-02-10

    An apparatus and method for generating homogeneous electromagnetic fields within a volume is disclosed. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 39 figs.

  4. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James T.

    1998-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  5. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, J.T.

    1998-05-05

    An apparatus and method are disclosed for generating homogeneous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set. 55 figs.

  6. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James Terry

    1998-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially canceling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  7. Generating highly uniform electromagnetic field characteristics

    DOEpatents

    Crow, James T.

    1997-01-01

    An apparatus and method for generating homogenous electromagnetic fields within a volume. The homogeneity provided may be for magnetic and/or electric fields, and for field magnitude, radial gradient, or higher order radial derivative. The invention comprises conductive pathways oriented mirror symmetrically about a desired region of homogeneity. A corresponding apparatus and method is provided for substantially cancelling the electromagnetic field outside of the apparatus, comprising a second set of conductive pathways placed outside the first set.

  8. Biomarkers of induced electromagnetic field and cancer.

    PubMed

    Behari, J; Paulraj, R

    2007-01-01

    The present article delineates the epidemiological and experimental studies of electromagnetic field which affects various tissues of human body. These affects lead to cell proliferation, which may lead to cancer formation. Certain biomarkers have been identified which are one way or the other responsible for tumor promotion or co-promotion. These are (i) melatonin, a hormone secreted by pineal gland, (ii) Ca2+, which is essential in the regulation of the resting membrane potential and in the sequence of events in synaptic excitation and neurotransmitter, release are affected by electromagnetic field, (iii) ornithine decarboxylase (ODC), a rate-limiting enzyme in the biosynthesis of polyamines, considered as a useful biological marker; over expression of ODC can cause cell transformation and enhancement of tumor promotion. (iv) protein kinase is an enzyme, which transfers phosphate groups from ATP to hydroxyl groups in the amino acid chains of acceptor proteins, and (v) Na+-K+ ATPase, which transports sodium and potassium ions across the membrane has a critical role in living cells. The various possible mechanisms depending upon non equilibrium thermodynamics, co-operativism, stochastic and resonance are discussed as possible models of signal transduction in cytosol, thereby controlling the transcription phenomena. Finally a mechanism comprising the extremely low frequency and radio frequency (RF)/microwave (MW) modulated field is compared.

  9. Nanomechanical electric and electromagnetic field sensor

    DOEpatents

    Datskos, Panagiotis George; Lavrik, Nickolay

    2015-03-24

    The present invention provides a system for detecting and analyzing at least one of an electric field and an electromagnetic field. The system includes a micro/nanomechanical oscillator which oscillates in the presence of at least one of the electric field and the electromagnetic field. The micro/nanomechanical oscillator includes a dense array of cantilevers mounted to a substrate. A charge localized on a tip of each cantilever interacts with and oscillates in the presence of the electric and/or electromagnetic field. The system further includes a subsystem for recording the movement of the cantilever to extract information from the electric and/or electromagnetic field. The system further includes a means of adjusting a stiffness of the cantilever to heterodyne tune an operating frequency of the system over a frequency range.

  10. Enhanced electro-magnetic energy transfer between a hot and cold body at close spacing due to evanescent fields

    SciTech Connect

    Raynolds, J.E.

    1998-10-01

    Theoretical studies have demonstrated that the energy transfer between a hot and cold body at close spacing (on the order of the radiation wavelength) can greatly exceed the limit for black body radiation (ie, Power = {sigma}T{sup 4}). This effect, due to the coupling of evanescent fields, presents an attractive option for thermo-photovoltaic (TPV) applications (assuming the considerable technical challenges can be overcome). The magnitude of the enhanced energy transfer depends on the optical properties of the hot and cold bodies as characterized by the dielectric functions of the respective materials. The present study considers five different situations as specified by the materials choices for the hot/cold sides: metal/metal, metal/insulator, metal/semiconductor, insulator/insulator, and semiconductor/semiconductor. For each situation, the dielectric functions are specified by typical models. An increase in energy transfer (relative to the black body law) is found for all situations considered, for separations less than one micron, assuming a temperature difference of 1,000 C. The metal/metal situation has the highest increase vs. separation while the semiconductor/semiconductor has the lowest. Factor-of-ten increases are obtained at roughly 0.1 microns for the metal/metal and roughly 0.02 microns for the metal/semiconductor. These studies are helping to increase the understanding of the close-spaced effect in the context of a radiator/TPV context.

  11. Interaction of electromagnetic fields and biological tissues

    NASA Astrophysics Data System (ADS)

    Darshan Shrivastava, Bhakt; Barde, Ravindra; Mishra, Ashutosh; Phadke, S.

    2014-09-01

    This paper deals with the electromagnetic field interact in biological tissues. It is actually one of the important challenges for the electromagnetic field for the recent years. The experimental techniques are use in Broad-band Dielectric Measurement (BDM) with LCR meters. The authors used Bones and scales of Fish taken from Narmada River (Rajghat Dist. Barwani) as biological tissues. Experimental work carried out done in inter-university consortium (IUC) Indore. The major difficulties that appear are related to the material properties, to the effect of the electromagnetic problem and to the thermal model of the biological tissues.

  12. Narrow field electromagnetic sensor system and method

    DOEpatents

    McEwan, Thomas E.

    1996-01-01

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments.

  13. Narrow field electromagnetic sensor system and method

    DOEpatents

    McEwan, T.E.

    1996-11-19

    A narrow field electromagnetic sensor system and method of sensing a characteristic of an object provide the capability to realize a characteristic of an object such as density, thickness, or presence, for any desired coordinate position on the object. One application is imaging. The sensor can also be used as an obstruction detector or an electronic trip wire with a narrow field without the disadvantages of impaired performance when exposed to dirt, snow, rain, or sunlight. The sensor employs a transmitter for transmitting a sequence of electromagnetic signals in response to a transmit timing signal, a receiver for sampling only the initial direct RF path of the electromagnetic signal while excluding all other electromagnetic signals in response to a receive timing signal, and a signal processor for processing the sampled direct RF path electromagnetic signal and providing an indication of the characteristic of an object. Usually, the electromagnetic signal is a short RF burst and the obstruction must provide a substantially complete eclipse of the direct RF path. By employing time-of-flight techniques, a timing circuit controls the receiver to sample only the initial direct RF path of the electromagnetic signal while not sampling indirect path electromagnetic signals. The sensor system also incorporates circuitry for ultra-wideband spread spectrum operation that reduces interference to and from other RF services while allowing co-location of multiple electronic sensors without the need for frequency assignments. 12 figs.

  14. Electromagnetic field enhancement in the gap between two Au nanoparticles: the size of hot site probed by surface-enhanced Raman scattering.

    PubMed

    Kim, Kwan; Shin, Dongha; Kim, Kyung Lock; Shin, Kuan Soo

    2010-04-21

    We have estimated the apparent size of the 'hot' site for surface-enhanced Raman scattering (SERS) located within the gap between two spherical Au nanoparticles. Initially, 55-nm sized Au nanoparticles are laid on a thiol-group terminated silane film, and then 1,4-phenylenediisocyanide (1,4-PDI) molecules are self-assembled onto the Au nanoparticles. 1,4-PDI is bonded to Au by forming one Au-CN bond, with another isocyanide group being pendent with respect to the Au surface. Up to this point, no Raman scattering is detected at all for 1,4-PDI. Upon attaching new Au nanoparticles onto the pendent isocyanide groups of 1,4-PDI, a Raman signal is distinctly observed. In agreement with the finite-difference time-domain (FDTD) calculation, this is understood in terms of the electromagnetic hot sites formed at the gaps between two Au nanoparticles. The Raman signal does not increase further, however, even after the adsorption of additional 1,4-PDI onto the vacant surfaces of the second Au nanoparticles. To a rough estimate, about 400 molecules residing only within a 10-nm diameter area of the center of the gap, adsorbed in the first stage, are then conjectured to have contributed most of the measured Raman signal of 1,4-PDI. This apparently indicates that the size of 'hot' site is very limited.

  15. Cytotoxicity of temozolomide on human glioblastoma cells is enhanced by the concomitant exposure to an extremely low-frequency electromagnetic field (100Hz, 100G).

    PubMed

    Akbarnejad, Zeinab; Eskandary, Hossein; Dini, Luciana; Vergallo, Cristian; Nematollahi-Mahani, Seyed Noureddin; Farsinejad, Alireza; Abadi, Maryam Fekri Soofi; Ahmadi, Meysam

    2017-08-01

    Glioblastoma multiforme (GBM) is the most malignant brain cancer that causes high mortality in humans. It responds poorly to the most common cancer treatments, such as surgery, chemo- and radiation therapy. Temozolomide (TMZ) is an alkylating agent that has been widely used to treat GBM; resistance to this drug is often found. One unexplored possibility for overcoming this resistance is a treatment based on concomitant exposure to electromagnetic fields (EMF) and TMZ. Indeed, many evidences show that EMF affects cancer cells and drug performance. In this study, we evaluated the potential synergistic effect of 100μM TMZ and EMF (100Hz, 100G) on two human glioma cells line, i.e., U87 and T98G above single treatments, TMZ or EMF. Co-treatment synergistically enhanced apoptosis in U87 and T98G cells, by increasing the expression of P53, Bax, and Caspase-3 and decreasing that of Bcl-2 and Cyclin-D1. We also observed an increase in reactive oxygen species (ROS) production and the overexpression of the heme oxygenase-1 (HO-1) gene in comparison to controls. In conclusion, since EMF enhanced the apoptotic effect of TMZ, possibly through a redox regulation mechanism, the TMZ/EMF combination may be effective for glioma cancer treating. Further studies are needed to reveal the action mechanism of this possible novel therapeutic approach. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  16. Program For Displaying Computed Electromagnetic Fields

    NASA Technical Reports Server (NTRS)

    Hom, Kam W.

    1995-01-01

    EM-ANIMATE computer program specialized visualization displays and animates output data on near fields and surface currents computed by electromagnetic-field program - in particular MOM3D (LAR-15074). Program based on windows and contains user-friendly, graphical interface for setting viewing options, selecting cases, manipulating files, and like. Written in FORTRAN 77. EM-ANIMATE also available as part of package, COS-10048, includes MOM3D, IRIS program computing near-field and surface-current solutions of electromagnetic-field equations.

  17. Controlling the Electromagnetic Field Confinement with Metamaterials

    PubMed Central

    Bonache, Jordi; Zamora, Gerard; Paredes, Ferran; Zuffanelli, Simone; Aguilà, Pau; Martín, Ferran

    2016-01-01

    The definition of a precise illumination region is essential in many applications where the electromagnetic field should be confined in some specific volume. By using conventional structures, it is difficult to achieve an adequate confinement distance (or volume) with negligible levels of radiation leakage beyond it. Although metamaterial structures and metasurfaces are well-known to provide high controllability of their electromagnetic properties, this feature has not yet been applied to solve this problem. We present a method of electromagnetic field confinement based on the generation of evanescent waves by means of metamaterial structures. With this method, the confinement volume can be controlled, namely, it is possible to define a large area with an intense field without radiation leakage. A prototype working in the microwave region has been implemented, and very good agreement between the measurements and the theoretical prediction of field distribution has been obtained. PMID:27886230

  18. Controlling the Electromagnetic Field Confinement with Metamaterials

    NASA Astrophysics Data System (ADS)

    Bonache, Jordi; Zamora, Gerard; Paredes, Ferran; Zuffanelli, Simone; Aguilà, Pau; Martín, Ferran

    2016-11-01

    The definition of a precise illumination region is essential in many applications where the electromagnetic field should be confined in some specific volume. By using conventional structures, it is difficult to achieve an adequate confinement distance (or volume) with negligible levels of radiation leakage beyond it. Although metamaterial structures and metasurfaces are well-known to provide high controllability of their electromagnetic properties, this feature has not yet been applied to solve this problem. We present a method of electromagnetic field confinement based on the generation of evanescent waves by means of metamaterial structures. With this method, the confinement volume can be controlled, namely, it is possible to define a large area with an intense field without radiation leakage. A prototype working in the microwave region has been implemented, and very good agreement between the measurements and the theoretical prediction of field distribution has been obtained.

  19. Characterizing and Designing Localized Electromagnetic Fields

    NASA Astrophysics Data System (ADS)

    Borzdov, Georgy N.

    2004-11-01

    An approach to characterizing and designing localized electromagnetic fields in complex media and free space, based on the use of differentiable manifolds, differentiable mappings, and the rotation group, is discussed. Families of exact time-harmonic solutions to Maxwell's equations -- standing waves defined by spherical harmonics, and localized fields defined by the rotation group -- are presented.

  20. Differential form representation of stochastic electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Haider, Michael; Russer, Johannes A.

    2017-09-01

    In this work, we revisit the theory of stochastic electromagnetic fields using exterior differential forms. We present a short overview as well as a brief introduction to the application of differential forms in electromagnetic theory. Within the framework of exterior calculus we derive equations for the second order moments, describing stochastic electromagnetic fields. Since the resulting objects are continuous quantities in space, a discretization scheme based on the Method of Moments (MoM) is introduced for numerical treatment. The MoM is applied in such a way, that the notation of exterior calculus is maintained while we still arrive at the same set of algebraic equations as obtained for the case of formulating the theory using the traditional notation of vector calculus. We conclude with an analytic calculation of the radiated electric field of two Hertzian dipole, excited by uncorrelated random currents.

  1. Electromagnetically induced transparency in modulated laser fields

    NASA Astrophysics Data System (ADS)

    Jiao, Yuechun; Yang, Zhiwei; Zhang, Hao; Zhang, Linjie; Raithel, Georg; Zhao, Jianming; Jia, Suotang

    2017-02-01

    We study electromagnetically induced transparency (EIT) in a room-temperature cesium vapor cell using wavelength-modulated probe laser light. In the utilized cascade level scheme, the probe laser drives the lower transition 6S {}1/2(F = 4) → 6P {}3/2 (F’ = 5), while the coupling laser drives the Rydberg transition 6P {}3/2 → 57S {}1/2. The probe laser has a fixed average frequency and is modulated at a frequency of a few kHz, with a variable modulation amplitude in the range of tens of MHz. The probe transmission is measured as a function of the detuning of the coupling laser from the Rydberg resonance. The first-harmonic demodulated EIT signal has two peaks that are, in the case of large modulation amplitude, separated by the peak-to-peak modulation amplitude of the probe laser times a scaling factor {λ }{{p}}/{λ }{{c}}, where {λ }{{p}} and {λ }{{c}} are the probe- and coupling-laser wavelengths. The scaling factor is due to Doppler shifts in the EIT geometry. Second-harmonic demodulated EIT signals, obtained with small modulation amplitudes, yield spectral lines that are much narrower than corresponding lines in the modulation-free EIT spectra. The resultant spectroscopic resolution enhancement is conducive to improved measurements of radio-frequency (RF) fields based on Rydberg-atom EIT, an approach in which the response of Rydberg atoms to RF fields is exploited to characterize RF fields. Here, we employ wavelength modulation spectroscopy to reduce the uncertainty of atom-based frequency and field measurement of an RF field in the VHF radio band.

  2. Electromagnetic fields in bone repair and adaptation

    NASA Astrophysics Data System (ADS)

    McLeod, Kenneth J.; Rubin, Clinton T.; Donahue, Henry J.

    1995-01-01

    The treatment of delayed union of bone fractures has served for the past 20 years as the principal testing ground for determining whether nonionizing electromagnetic fields can have any substantial, long-term effects in clinical medicine. Recent double-blinded clinical trials have confirmed the significance of the reported effects on bone healing and have led to the suggestion that electromagnetic fields may also be useful in the treatment of other orthopedic problems such as fresh fractures, stabilization of prosthetic implants, or even the prevention or treatment of osteoporosis. However, the design of appropriate treatment regimens for these new applications would be greatly facilitated if it were understood how the biological cells within bone tissue sense these low-frequency, and remarkably low level, electromagnetic fields. Here we address the engineering and physical science aspects of this problem. We review the characteristics of clinically used electromagnetic fields and discuss which components of these fields may actually be responsible for altering the activity of the bone cells. We then consider several physical mechanisms which have been proposed to explain how the cells within the bone or fracture tissue detect this field component.

  3. Electromagnetic field interactions with biological systems

    SciTech Connect

    Frey, A.H. )

    1993-02-01

    This is a report on Symposia organized by the International Society for Bioelectricity and presented at the 1992 FASEB Meeting. The presentations summarized here were intended to provide a sampling of new and fruitful lines of research. The theme topics for the Symposia were cancer, neural function, cell signaling, pineal gland function, and immune system interactions. Living organisms are complex electrochemical systems that evolved over billions of years in a world with a relatively simple weak magnetic field and with few electromagnetic energy emitters. As is characteristic of living organisms, they interacted with and adapted to this environment of electric and magnetic fields. In recent years there has been a massive introduction of equipment that emits electromagnetic fields in an enormous range of new frequencies, modulations, and intensities. As living organisms have only recently found themselves immersed in this new and virtually ubiquitous environment, they have not had the opportunity to adapt to it. This gives biologists the opportunity to use these electromagnetic fields as probes to study the functioning of living systems. This is a significant opportunity, as new approaches to studying living systems so often provide the means to make great leaps in science. In recent years, a diversity of biologists have carried out experiments using electromagnetic fields to study the function of living cells and systems. This approach is now becoming quite fruitful and is yielding data that are advancing our knowledge in diverse areas of biology. 25 refs., 6 figs., 3 tabs.

  4. Photon Propagation in Slowly Varying Electromagnetic Fields

    NASA Astrophysics Data System (ADS)

    Karbstein, F.

    2017-03-01

    Effective theory of soft photons in slowly varying electromagnetic background fields is studied at one-loop order in QED. This is of relevance for the study of all-optical signatures of quantum vacuum nonlinearity in realistic electromagnetic background fields as provided by high-intensity lasers. The central result derived in this article is a new analytical expression for the photon polarization tensor in two linearly polarized counterpropagating pulsed Gaussian laser beams. Treating the peak field strengths of both laser beams as free parameters, this field configuration can be considered as interpolating between the limiting cases of a purely right- or left-moving laser beam (if one of the peak field strengths is set equal to zero) and the standing-wave type scenario with two counter-propagating beams of equal strength.

  5. Radiated fields from an electromagnetic pulse simulator

    NASA Astrophysics Data System (ADS)

    Pelletier, M.; Delisle, G. Y.; Kashyap, S.

    Simulators of electromagnetic pulses allow generation within a limited time of very high-intensity fields such as those produced in a nuclear explosion. These fields can be radiated out of the test zone at a lower but nevertheless significant level; if the intensity of these fields is sufficiently high, damage to humans and electronic equipment can result. An evaluation of the potential danger of these simulator emissions requires knowledge of the amplitude, duration, and the energy of the radiated impulses. A technique is presented for calculating the fields radiated by a parallel-plane electromagnetic pulse simulator. The same method can also be applied to a rhombic type simulator. Sample numerical results are presented along with the calculations of the energy and power density and a discussion of the formation of the field in the frequency domain.

  6. Electromagnetic fields and infant incubators.

    PubMed

    Bearer, C F

    1994-01-01

    Two models of infant incubators were studied to determine the strength of the magnetic field generated by the heater and fan motors. Measurements were taken at intervals along the center line of the incubator. The results show that fields greater than 100 milligauss and 25 milligauss were measured in the C-86 and C-100 model Isolettes, respectively.

  7. Electromagnetic field parameters and instrumentation

    NASA Astrophysics Data System (ADS)

    Sheppard, A. R.; Jones, R. A.; Stell, M. E.; Adey, W. R.; Bawin, S.

    1986-07-01

    We studied the effects of the electric and magnetic components of a Loran-C type waveform on three biological systems. Neurochemical assays of brain neurotransmitter substances indicate field-related changes in the levels of norepinephrine in the hippocampus and in the number and affinities of the opiate receptors in the cortex. Behavioral data showed that rats trained in an operant conditioning task did not reliably detect any electric field strength used. Biochemical data demonstrated that the Loran-C field did not modify basal ornithine decarboxylase activity in primary bone cells.

  8. LEM—electromagnetic fields measurement laboratory

    NASA Astrophysics Data System (ADS)

    Annino, A.; Falciglia, F.; Musumeci, F.; Oliveri, M.; Privitera, G.; Triglia, A.

    2000-04-01

    The widespread presence of electromagnetic waves and the relative problems regarding them have favored the constitution of the LEM at the DMFCI in Catania University, where competence has been developing in this sector for about 10 years. Full operativeness has been reached as far as the electromagnetic field measurements in anthropized environments are concerned. Other research will be undertaken as soon as further funds are available. Some problems connected with the perfecting of measurements instruments and the results of emission measurements of cellular telephones are presented.

  9. Gene transcription and electromagnetic fields

    SciTech Connect

    Henderson, A.S.

    1992-01-01

    Our overall aim is to obtain sufficient information to allow us to ultimately determine whether ELF EM field exposure is an initiating factor in neoplastic transformation and/or if exposure can mimic characteristics of the second-step counterpart in neoplastic disease. This aim is based on our previous findings that levels of some transcripts are increased in cells exposed to EM fields. While the research is basic in nature, the ramifications have bearing on the general safety of exposure to EM fields in industrial and everyday life. A large array of diverse biological effects are reported to occur as the result of exposure to elf EM fields, suggesting that the cell response to EM fields is at a basic level, presumably initiated by molecular and/or biophysical events at the cell membrane. The hypothesized route is a signal transduction pathway involving membrane calcium fluxes. Information flow resulting from signal transduction can mediate the induction of regulatory factors in the cell, and directly affect how transcription is regulated.

  10. Electromagnetic Fields, 2nd Edition

    NASA Astrophysics Data System (ADS)

    Wangsness, Roald K.

    1986-07-01

    This revised edition provides patient guidance in its clear and organized presentation of problems. It is rich in variety, large in number and provides very careful treatment of relativity. One outstanding feature is the inclusion of simple, standard examples demonstrated in different methods that will allow students to enhance and understand their calculating abilities. There are over 145 worked examples; virtually all of the standard problems are included.

  11. Coherent polarization driven by external electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Apostol, M.; Ganciu, M.

    2010-11-01

    The coherent interaction of the electromagnetic radiation with an ensemble of polarizable, identical particles with two energy levels is investigated in the presence of external electromagnetic fields. The coupled non-linear equations of motion are solved in the stationary regime and in the limit of small coupling constants. It is shown that an external electromagnetic field may induce a macroscopic occupation of both the energy levels of the particles and the corresponding photon states, governed by a long-range order of the quantum phases of the internal motion (polarization) of the particles. A lasing effect is thereby obtained, controlled by the external field. Its main characteristics are estimated for typical atomic matter and atomic nuclei. For atomic matter the effect may be considerable (for usual external fields), while for atomic nuclei the effect is extremely small (practically insignificant), due to the great disparity in the coupling constants. In the absence of the external field, the solution, which is non-analytic in the coupling constant, corresponds to a second-order phase transition (super-radiance), which was previously investigated.

  12. Electromagnetic field of a linear antenna

    NASA Astrophysics Data System (ADS)

    Derby, Norman; Olbert, Stanislaw

    2008-11-01

    Animated computer simulations of the electric field of a radiating antenna can capture the attention of students in introductory electromagnetism courses and stimulate active discussions. The simulations raise questions not usually addressed in textbooks. In certain cases, some of the field lines appear to move toward the antenna, the speed of the field lines can change as they move, and the field lines exhibit strange behavior (circling or splitting) at certain points. Because their fields can be expressed in terms of elementary functions, animations of point dipole antennas are common, but animations showing the fields of antennas with more realistic lengths are not as common because analytical expressions for these fields are not as well known. We show that it is possible to derive analytical expressions in terms of elementary functions for the electromagnetic field of linear antennas of finite length. We draw attention to an open-source method for displaying the fine details within the field patterns and then give a general discussion of singular points and their motions, derive expressions for their location and phase velocity, and apply these results to some of the phenomena that are visible in visualizations of the fields of various antennas.

  13. Electromagnetic field induced biological effects in humans.

    PubMed

    Kaszuba-Zwoińska, Jolanta; Gremba, Jerzy; Gałdzińska-Calik, Barbara; Wójcik-Piotrowicz, Karolina; Thor, Piotr J

    2015-01-01

    Exposure to artificial radio frequency electromagnetic fields (EMFs) has increased significantly in recent decades. Therefore, there is a growing scientific and social interest in its influence on health, even upon exposure significantly below the applicable standards. The intensity of electromagnetic radiation in human environment is increasing and currently reaches astronomical levels that had never before experienced on our planet. The most influential process of EMF impact on living organisms, is its direct tissue penetration. The current established standards of exposure to EMFs in Poland and in the rest of the world are based on the thermal effect. It is well known that weak EMF could cause all sorts of dramatic non-thermal effects in body cells, tissues and organs. The observed symptoms are hardly to assign to other environmental factors occurring simultaneously in the human environment. Although, there are still ongoing discussions on non-thermal effects of EMF influence, on May 31, 2011--International Agency for Research on Cancer (IARC)--Agenda of World Health Organization (WHO) has classified radio electromagnetic fields, to a category 2B as potentially carcinogenic. Electromagnetic fields can be dangerous not only because of the risk of cancer, but also other health problems, including electromagnetic hypersensitivity (EHS). Electromagnetic hypersensitivity (EHS) is a phenomenon characterized by the appearance of symptoms after exposure of people to electromagnetic fields, generated by EHS is characterized as a syndrome with a broad spectrum of non-specific multiple organ symptoms including both acute and chronic inflammatory processes located mainly in the skin and nervous systems, as well as in respiratory, cardiovascular systems, and musculoskeletal system. WHO does not consider the EHS as a disease-- defined on the basis of medical diagnosis and symptoms associated with any known syndrome. The symptoms may be associated with a single source of EMF

  14. Basic Discoveries in Electromagnetic Field Visualization

    NASA Astrophysics Data System (ADS)

    Shindo, Daisuke

    2014-01-01

    Basic discoveries in the electromagnetic field visualization are presented, mentioning the late Dr. A. Tonomura's significant achievements in this field. First, the discovery of the electron biprism interferences by G. Möllenstedt and his colleagues was noted. Having studied Möllenstedt's interference experiments, A. Tonomura and his colleagues have extended the electron holography system to clearly prove the physical reality of vector potentials, the so-called Aharonov-Bohm effect. They also succeeded in observing the dynamic motions of magnetic flux quanta (fluxons) in a superconducting Nb film. In a joint research with A. Tonomura, we succeeded in visualizing a fluxon pinned by an insulating particle in a high-Tc Y-Ba-Cu-O superconductor by combining electron holography and scanning ion microscopy. As the study of a scalar potential, the visualization of the orbits of electron-induced secondary electrons around positively charged biological specimens was noted. Finally, although the electromagnetic field analysis using electron holography on the basis of Maxwell's equations seems to be promising, it is pointed out that there have been some controversies on the interpretation and treatment of electromagnetic field.

  15. Subwavelength resonant antennas enhancing electromagnetic energy harvesting

    NASA Astrophysics Data System (ADS)

    Oumbe Tekam, Gabin; Ginis, Vincent; Seetharamdoo, Divitha; Danckaert, Jan

    2016-04-01

    In this work, an electromagnetic energy harvester operating at microwave frequencies is designed based on a cut- wire metasurface. This metamaterial is known to contain a quasistatic electric dipole resonator leading to a strong resonant electric response when illuminated by electromagnetic fields.1 Starting from an equivalent electrical circuit, we analytically design the parameters of the system to tune the resonance frequency of the harvester at the desired frequency band. Subsequently, we compare these results with numerical simulations, which have been obtained using finite elements numerical simulations. Finally, we optimize the design by investigating the best arrangement for energy harvesting by coupling in parallel and in series many single layers of cut-wire metasurfaces. We also discuss the implementation of different geometries and sizes of the cut-wire metasurface for achieving different center frequencies and bandwidths.

  16. Electromagnetic field radiation model for lightning strokes to tall structures

    SciTech Connect

    Motoyama, H.; Janischewskyj, W.; Hussein, A.M.; Chisholm, W.A.; Chang, J.S.; Rusan, R.

    1996-07-01

    This paper describes observation and analysis of electromagnetic field radiation from lightning strokes to tall structures. Electromagnetic field waveforms and current waveforms of lightning strokes to the CN Tower have been simultaneously measured since 1991. A new calculation model of electromagnetic field radiation is proposed. The proposed model consists of the lightning current propagation and distribution model and the electromagnetic field radiation model. Electromagnetic fields calculated by the proposed model, based on the observed lightning current at the CN Tower, agree well with the observed fields at 2km north of the tower.

  17. Systemic Effects of Electromagnetic Fields in Patients with Myocardial Infarction

    NASA Astrophysics Data System (ADS)

    Cañedo-Dorantes, L.; Valle, L.; Uruchurtu, E.; Medel, A.; García-Mayen, F.; Serrano-Luna, G.

    2003-09-01

    Healing of acute myocardial infarction (AMI) is associated with inflammatory response, which promotes healing and scar formation. Activation of a local inflammatory response in patients with sequel of AMI could have an important role to enhance angiogenesis and regeneration of hibernating myocardial tissue. Chronic arterial leg ulcers have a similar etiology, and healing has been promoted by exposure to extremely low frequency electromagnetic fields (ELF). We report the evolution of three AMI patients with sequel of AMI that were exposed to ELF.

  18. [Safety and electromagnetic compatibility in sanitary field].

    PubMed

    Bini, M; Feroldi, P; Ferri, C; Ignesti, A; Olmi, R; Priori, S; Riminesi, C; Tobia, L

    2012-01-01

    In sanitary field and especially in a hospital, multiple sources of non ionizing radiation are used for diagnostic and therapeutic aims. In sanitary sector both workers and users are present at the same time, and in some cases general population could need higher protection than workers in relationship to the exposition to electromagnetic fields. In order to protect health and safety of patients, general population and workers of hospitals and with the aim to identify, analyze, evaluate and study its level of significance, electrical, magnetic and electromagnetic sources Research Italian project Si.C.E.O. (Safety And Electromagnetic Compatibility In Sanitary Field) was instituted. Target of our research project was to deepen risk of exposition elements with analysis of outdoor (e.g. power lines, transmission cabinets) and indoor (e.g. equipment for physical therapy) sources, located in sanitary structures and to verify the level exposition of workers and common population end the respect of specific regulation, and finally to define technical and organizational measures really useful for protection and reduction of risk.

  19. On electromagnetic field problems in inhomogeneous media

    NASA Technical Reports Server (NTRS)

    Mohsen, A.

    1973-01-01

    Analysis of electromagnetic fields in inhomogeneous media is of practical interest in general scattering and propagation problems and in the study of lenses. For certain types of inhomogeneities, the fields may be represented in terms of two scalars. In a general orthogonal coordinate system, these potentials satisfy second order differential equations. Exact solutions of these equations are known only for a few particular cases and in general, an approximate or numerical technique must be employed. The present work reviews and generalizes some of the main methods of attack of the problem. The results are presented in a form appropriate for numerical computation.

  20. A New Theory of the Electromagnetic Field

    NASA Astrophysics Data System (ADS)

    Kriske, Richard

    2017-01-01

    This author has previously introduced a new theory of the Electromagnetic Field and its interaction with matter. There was from the start a problem with Einstein's formulation of Invariants and its use in describing The EM field. The photon produced by first varying a stationary Electric field in one observer's reference frame is not the same as a photon produced from varying the a stationary Magnetic Field. The Magnetic field photon is thought of as being ``off the mass shell''. The Quantum information seems to carry with it an ordering of these events. You see this ordering in Wick's theory and in Feynman diagrams. This author is proposing that other fields can vary first in another Observers reference frame, not just the ``Scalar Field'' or the ``Fermion Field'', but many other forms of Energy. If the ``Nuclear Field'' varies first, it results in Quantum information that produces a photon that has the Nuclear Field in it and also the Magnetic Field, this is the strange effect seen in Nuclear Magnetic Resonance. This author proposed that there is a large number of photons with different properties, because of this ordering of events that occurs in Quantum Information. One of these photons is the Neutrino which appears to be a three field photon. This is Kriske's Field Theory.

  1. Optimization methods in control of electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Angell, Thomas S.; Kleinman, Ralph E.

    1991-05-01

    This program is developing constructive methods for certain constrained optimization problems arising in the design and control of electromagnetic fields and in the identification of scattering objects. The problems addressed fall into three categories: (1) the design of antennas with optimal radiation characteristics measured in terms of directivity; (2) the control of the electromagnetic scattering characteristics of an object, in particular the minimization of its radar cross section, by the choice of material properties; and (3) the determination of the shape of scattering objects with various electromagnetic properties from scattered field data. The main thrust of the program is toward the development of constructive methods based on the use of complete families of solutions of the time-harmonic Maxwell equations in the infinite domain exterior to the radiating or scattering body. During the course of the work an increasing amount of attention has been devoted to the use of iterative methods for the solution of various direct and inverse problems. The continued investigation and development of these methods and their application in parameter identification has become a significant part of the program.

  2. Self field electromagnetism and quantum phenomena

    NASA Astrophysics Data System (ADS)

    Schatten, Kenneth H.

    1994-07-01

    Quantum Electrodynamics (QED) has been extremely successful inits predictive capability for atomic phenomena. Thus the greatest hope for any alternative view is solely to mimic the predictive capability of quantum mechanics (QM), and perhaps its usefulness will lie in gaining a better understanding of microscopic phenomena. Many ?paradoxes? and problematic situations emerge in QED. To combat the QED problems, the field of Stochastics Electrodynamics (SE) emerged, wherein a random ?zero point radiation? is assumed to fill all of space in an attmept to explain quantum phenomena, without some of the paradoxical concerns. SE, however, has greater failings. One is that the electromagnetic field energy must be infinit eto work. We have examined a deterministic side branch of SE, ?self field? electrodynamics, which may overcome the probelms of SE. Self field electrodynamics (SFE) utilizes the chaotic nature of electromagnetic emissions, as charges lose energy near atomic dimensions, to try to understand and mimic quantum phenomena. These fields and charges can ?interact with themselves? in a non-linear fashion, and may thereby explain many quantum phenomena from a semi-classical viewpoint. Referred to as self fields, they have gone by other names in the literature: ?evanesccent radiation?, ?virtual photons?, and ?vacuum fluctuations?. Using self fields, we discuss the uncertainty principles, the Casimir effects, and the black-body radiation spectrum, diffraction and interference effects, Schrodinger's equation, Planck's constant, and the nature of the electron and how they might be understood in the present framework. No new theory could ever replace QED. The self field view (if correct) would, at best, only serve to provide some understanding of the processes by which strange quantum phenomena occur at the atomic level. We discuss possible areas where experiments might be employed to test SFE, and areas where future work may lie.

  3. [Combined biological effect of electromagnetic fields and chemical substances (toxic)].

    PubMed

    Kamedula, M; Kamedula, T

    1996-01-01

    The authors present results of own measurements and examinations as well as the literature data on the occurrence and effect of direct, low and high frequency electromagnetic fields and chemicals. In real working conditions and in experimental conditions, the following relations can be observed: 1) concomitant occurrence of electromagnetic fields and chemicals, e.g. processes of electrolysis, inductive and dielectric heating; 2) experimental studies of combined effect of electromagnetic fields and chemicals on e.g. cancer development: 3) drug effect modified by electromagnetic fields; 4) effect of chemicals produced in materials under the influence of electromagnetic fields. There are only a few publications on medical examinations of workers exposed simultaneously to electromagnetic fields and chemicals. However, even in those reported studies, an attempt to distinguish changes in the health state due to electromagnetic fields, and due to chemicals has field. The studies of the effect of electromagnetic fields which modify the effect of carcinogenic substances have not yielded unequivocal results. Electromagnetic fields may modify significantly the effect of some psychotropic and hormonal drugs. Under the influence of pyrolisis, induced by thermal effect of electromagnetic fields, toxic substances or substances with harmful biological effect may occur in some materials.

  4. Electromagnetic field redistribution in hybridized plasmonic particle-film system

    NASA Astrophysics Data System (ADS)

    Fang, Yurui; Huang, Yingzhou

    2013-04-01

    Combining simulation and experiment, we demonstrate that a metal nanoparticle dimer on a gold film substrate can confine more energy in the particle/film gap because of the hybridization of the dimer resonant lever and the continuous state of the film. The hybridization may even make the electric field enhancement in the dimer/film gap stronger than in the gap between particles. The resonant peak can be tuned by varying the size of the particles and the film thickness. This electromagnetic field redistribution has tremendous applications in sensor, photocatalysis and solar cell, etc., especially considering ultrasensitive detection of tracing molecule on substrates.

  5. Geometrization conditions for perfect fluids, scalar fields, and electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Torre, Charles; Krongos, Dionisios

    2016-03-01

    The classical Rainich conditions are a system of geometric conditions, expressed purely in terms of the spacetime metric, which are necessary and sufficient for the metric to define a solution to the Einstein-Maxwell equations with a non-null electromagnetic field. We obtain analogous ``geometrization'' conditions for other matter sources. Specifically, we find geometric conditions which are necessary and sufficient for a metric to define a solution to the Einstein equations with a perfect fluid source, and to define a solution to the Einstein-scalar field equations. These conditions work in any dimension, allow for a cosmological constant, and allow for an arbitrary self-interaction potential in the scalar field case. We also generalize the classical Rainich conditions to include a cosmological constant and we obtain geometrization conditions which are applicable to the case of null electromagnetic fields. This work was supported in part by Grant No. OCI-1148331 from the National Science Foundation.

  6. Transient electromagnetic fields near large earthing systems

    SciTech Connect

    Grcev, L.D.; Menter, F.E.

    1996-05-01

    Electromagnetic compatibility studies require knowledge of transient voltages that may be developed near earthing systems during lightning discharge, since such voltages may be coupled to sensitive electronic circuits. For such purpose accurate evaluation of transient electric field near to and/or at the surface of the grounding conductors is necessary. In this paper, a procedure for computation of transient fields near large earthing systems, as a response to a typical lightning current impulse, based on computational methodology developed in the field of antennas, is presented. Computed results are favorably compared with published measurement results. The model is applied to check the common assumption that the soil ionization can be neglected in case of large earthing systems. Presented results show that the soil ionization threshold is met and exceeded during typical lightning discharge in a large earthing system.

  7. Near-field radiofrequency electromagnetic exposure assessment.

    PubMed

    Rubtsova, Nina; Perov, Sergey; Belaya, Olga; Kuster, Niels; Balzano, Quirino

    2015-09-01

    Personal wireless telecommunication devices, such as radiofrequency (RF) electromagnetic field (EMF) sources operated in vicinity of human body, have possible adverse health effects. Therefore, the correct EMF assessment is necessary in their near field. According to international near-field measurement criteria, the specific absorption rate (SAR) is used for absorbed energy distribution assessment in tissue simulating liquid phantoms. The aim of this investigation is to validate the relationship between the H-field of incident EMF and absorbed energy in phantoms. Three typical wireless telecommunication system frequencies are considered (900, 1800 and 2450 MHz). The EMF source at each frequency is an appropriate half-wave dipole antenna and the absorbing medium is a flat phantom filled with the suitable tissue simulating liquid. Two methods for SAR estimation have been used: standard procedure based on E-field measured in tissue simulating medium and a proposed evaluation by measuring the incident H-field. Compared SAR estimations were performed for various distances between sources and phantom. Also, these research data were compared with simulation results, obtained by using finite-difference time-domain method. The acquired data help to determine the source near-field space characterized by the smallest deviation between SAR estimation methods. So, this region near the RF source is suitable for correct RF energy absorption assessment using the magnetic component of the RF fields.

  8. Electromagnetic field interacting with a semi-infinite plasma.

    PubMed

    Apostol, M; Vaman, G

    2009-07-01

    Plasmon and polariton modes are derived for an ideal semi-infinite (half-space) plasma by using a general, unifying procedure based on the equation of motion of the polarization and the electromagnetic potentials. Known results are reproduced in a much more direct manner, and new ones are derived. The approach consists of representing the charge disturbances by a displacement field in the positions of the moving particles (electrons). The propagation of an electromagnetic wave in this plasma is treated by using the retarded electromagnetic potentials. The resulting integral equations are solved, and the reflected and refracted fields are computed, as well as the reflection coefficient. Generalized Fresnel relations are thereby obtained for any incidence angle and polarization. Bulk and surface plasmon-polariton modes are identified. As is well known, the field inside the plasma is either damped (evanescent) or propagating (transparency regime), and the reflection coefficient exhibits an abrupt enhancement on passing from the propagating regime to the damped one (total reflection).

  9. Super strong electromagnetic fields and their applications

    SciTech Connect

    Bulanov, Sergei V.

    2007-07-11

    The progress in the ultra-intense laser technologies continues to open up new fields of physics. The laser accelerator development enters a new matured stage at which it becomes possible to manipulate in a controllable way the parameters of accelerated charged particle beams. In the electron acceleration the particle injection by breaking wake waves left by the laser pulse in underdense plasmas or by interacting two laser pulses results in the quasi-mono-energetic beam production. When the ions are accelerated during the laser-matter interaction the tailored multi-layer foil targets provide conditions for the high quality proton beam generation. When the laser pulse radiation pressure is dominant, the laser energy is transformed efficiently into the energy of fast ions. Ultrahigh intense electromagnetic fields can be generated due to the laser pulse compression, carrier frequency upshifting, and focusing by a counterpropagating breaking plasma wave, relativistic flying mirrors.

  10. Electromagnetic fields with vanishing scalar invariants

    NASA Astrophysics Data System (ADS)

    Ortaggio, Marcello; Pravda, Vojtěch

    2016-06-01

    We determine the class of p-forms {\\boldsymbol{F}} that possess vanishing scalar invariants (VSIs) at arbitrary order in an n-dimensional spacetime. Namely, we prove that {\\boldsymbol{F}} is a VSI if and only if if it is of type N, its multiple null direction {\\boldsymbol{\\ell }} is ‘degenerate Kundt’, and {\\pounds }{\\boldsymbol{\\ell }}{\\boldsymbol{F}}=0. The result is theory-independent. Next, we discuss the special case of Maxwell fields, both at the level of test fields and of the full Einstein-Maxwell equations. These describe electromagnetic non-expanding waves propagating in various Kundt spacetimes. We further point out that a subset of these solutions possesses a universal property, i.e. they also solve (virtually) any generalized (non-linear and with higher derivatives) electrodynamics, possibly also coupled to Einstein’s gravity.

  11. Electromagnetic field patterning or crystal light

    NASA Astrophysics Data System (ADS)

    Słupski, Piotr; Wymysłowski, Artur; Czarczyński, Wojciech

    2016-12-01

    Using the orbital angular momentum of light for the development of a vortex interferometer, the underlying physics requires microwave/RF models,1 as well as quantum mechanics for light1, 2 and fluid flow for semiconductor devices.3, 4 The combination of the aforementioned physical models yields simulations and results such as optical lattices,1 or an Inverse Farday effect.5 The latter is explained as the absorption of optical angular momentum, generating extremely high instantenous magnetic fields due to radiation friction. An algorithmic reduction across the computational methods used in microwaves, lasers, quantum optics and holography is performed in order to explain electromagnetic field interactions in a single computational framework. This work presents a computational model for photon-electron interactions, being a simplified gauge theory described using differentials or disturbances (photons) instead of integrals or fields. The model is based on treating the Z-axis variables as a Laplace fluid with spatial harmonics, and the XY plane as Maxwell's equations on boundaries. The result is a unified, coherent, graphical computational method of describing the photon qualitatively, quantitatively and with proportion. The model relies on five variables and is described using two equations, which use emitted power, cavity wavelength, input frequency, phase and time. Phase is treated as a rotated physical dimension under gauge theory of Feynmann's QED. In essence, this model allows the electromagnetic field to be treated with it's specific crystallography. The model itself is described in Python programming language. PACS 42.50.Pq, 31.30.J-, 03.70.+k, 11.10.-z, 67.10.Hk

  12. Enhancement of Cortical Network Activity in vitro and Promotion of GABAergic Neurogenesis by Stimulation with an Electromagnetic Field with a 150 MHz Carrier Wave Pulsed with an Alternating 10 and 16 Hz Modulation.

    PubMed

    Gramowski-Voß, Alexandra; Schwertle, Hans-Joachim; Pielka, Anna-Maria; Schultz, Luise; Steder, Anne; Jügelt, Konstantin; Axmann, Jürgen; Pries, Wolfgang

    2015-01-01

    In recent years, various stimuli were identified capable of enhancing neurogenesis, a process which is dysfunctional in the senescent brain and in neurodegenerative and certain neuropsychiatric diseases. Applications of electromagnetic fields to brain tissue have been shown to affect cellular properties and their importance for therapies in medicine is recognized. In this study, differentiating murine cortical networks on multiwell microelectrode arrays were repeatedly exposed to an extremely low-electromagnetic field (ELEMF) with alternating 10 and 16 Hz frequencies piggy backed onto a 150 MHz carrier frequency. The ELEMF exposure stimulated the electrical network activity and intensified the structure of bursts. Further, the exposure to electromagnetic fields within the first 28 days in vitro of the differentiation of the network activity induced also reorganization within the burst structure. This effect was already most pronounced at 14 days in vitro after 10 days of exposure. Overall, the development of cortical activity under these conditions was accelerated. These functional electrophysiological changes were accompanied by morphological ones. The percentage of neurons in the neuron glia co-culture was increased without affecting the total number of cells, indicating an enhancement of neurogenesis. The ELEMF exposure selectively promoted the proliferation of a particular population of neurons, evidenced by the increased proportion of GABAergic neurons. The results support the initial hypothesis that this kind of ELEMF stimulation could be a treatment option for specific indications with promising potential for CNS applications, especially for degenerative diseases, such as Alzheimer's disease and other dementias.

  13. On Acceptable Exposures to Short Pulses of Electromagnetic Fields

    DTIC Science & Technology

    2015-09-01

    NAWCWD TP 8791 On Acceptable Exposures to Short Pulses of Electromagnetic Fields by Francis X. Canning, PhD Physics...prepared in response to a request to study the effects of exposure to short pulses of electromagnetic fields. The author is a physicist at the Naval... Exposures to Short Pulses of Electromagnetic Fields (U) 5a. CONTRACT NUMBER N/A 5b. GRANT NUMBER N/A 5c. PROGRAM ELEMENT NUMBER N/A 6. AUTHOR(S

  14. Evaluation of uncertainty in the measurement of environmental electromagnetic fields.

    PubMed

    Vulević, B; Osmokrović, P

    2010-09-01

    With regard to Non-ionising radiation protection, the relationship between human exposure to electromagnetic fields and health is controversial. Electromagnetic fields have become omnipresent in the daily environment. This paper assesses the problem of how to compare a measurement result with a limit fixed by the standard for human exposure to electric, magnetic and electromagnetic fields (0 Hz-300 GHz). The purpose of the paper is an appropriate representation of the basic information about evaluation of measurement uncertainty.

  15. Note on Inverse Bremsstrahlung in a Strong Electromagnetic Field

    DOE R&D Accomplishments Database

    Bethe, H. A.

    1972-09-01

    The collisional energy loss of an electron undergoing forced oscillation in an electromagnetic field behaves quite differently in the low and high intensity limits. ... It is shown that in the case of an electromagnetic field v {sub o} >> v {sub t} the rate of transfer is much slower, and actually decreases with the strength of the field.

  16. Plant Responses to High Frequency Electromagnetic Fields

    PubMed Central

    Vian, Alain; Davies, Eric; Gendraud, Michel; Bonnet, Pierre

    2016-01-01

    High frequency nonionizing electromagnetic fields (HF-EMF) that are increasingly present in the environment constitute a genuine environmental stimulus able to evoke specific responses in plants that share many similarities with those observed after a stressful treatment. Plants constitute an outstanding model to study such interactions since their architecture (high surface area to volume ratio) optimizes their interaction with the environment. In the present review, after identifying the main exposure devices (transverse and gigahertz electromagnetic cells, wave guide, and mode stirred reverberating chamber) and general physics laws that govern EMF interactions with plants, we illustrate some of the observed responses after exposure to HF-EMF at the cellular, molecular, and whole plant scale. Indeed, numerous metabolic activities (reactive oxygen species metabolism, α- and β-amylase, Krebs cycle, pentose phosphate pathway, chlorophyll content, terpene emission, etc.) are modified, gene expression altered (calmodulin, calcium-dependent protein kinase, and proteinase inhibitor), and growth reduced (stem elongation and dry weight) after low power (i.e., nonthermal) HF-EMF exposure. These changes occur not only in the tissues directly exposed but also systemically in distant tissues. While the long-term impact of these metabolic changes remains largely unknown, we propose to consider nonionizing HF-EMF radiation as a noninjurious, genuine environmental factor that readily evokes changes in plant metabolism. PMID:26981524

  17. Properties of electromagnetic field focusing probe.

    PubMed

    Yamanashi, W S; Yassa, N A; Hill, D L; Patil, A A; Lester, P D

    1988-11-01

    The electromagnetic field focusing (EFF) apparatus consists of a radio frequency generator, solenoidal coil, and a hand-held or catheter probe. Applications such as aneurysm treatment, angioplasty, and neurosurgery in various models have been reported. The probe is operated in the near field (within one wavelength of an electromagnetic field source) of a coil inducing eddy currents in biological tissues, producing maximal convergence of the induced current at the probe tip. The probe produces very high temperatures depending on the wattage selected for the given radio frequency of output power. The high temperature can be used in cutting, cauterizing, or vaporizing. The EFF probe is comparable to different types of lasers and to bipolar and monopolar cautery. The EFF probe can be used with catheters or endoscopes. Objectives of this study were to determine what the thermal properties of the EFF probe are and how instrument parameters can be varied to obtain different temperatures in the tissue near the probe tip. In this study an F2 catheter was used as an insulated sheath and the tip of the guide wire was used as the probe tip. Different powers, wave forms, coil-to-probe distances, and probe-tip lengths were tested on a phantom that simulates tissue electrical properties. Some of the experiments were conducted under normal saline to simulate treatment of tissue with body fluids such as blood vessels or brain tissue under normal physiologic conditions. It is concluded that the EFF probe has the advantages of easy manipulation, relative safety, cost effectiveness, and a high degree of spatial control.(ABSTRACT TRUNCATED AT 250 WORDS)

  18. Synergistic health effects between chemical pollutants and electromagnetic fields.

    PubMed

    Ledoigt, Gérard; Sta, Chaima; Goujon, Eric; Souguir, Dalila; El Ferjani, Ezzeddine

    2015-01-01

    Humans and ecosystems are exposed to highly variable and unknown cocktail of chemicals and radiations. Although individual chemicals are typically present at low concentrations, they can interact with each other resulting in additive or potentially synergistic mixture effects. This was also observed with products obtained by radiation actions such as sunlight or electromagnetic fields that can change the effects of chemicals, such as pesticides, and metal trace elements on health. Concomitant presence of various pesticides and their transformation products adds further complexity to chemical risk assessment since chronic inflammation is a key step for cancer promotion. Degradation of a parent molecule can produce several by-products which can trigger various toxic effects with different impacts on health and environment. For instance, the cocktail of sunlight irradiated sulcotrione pesticide has a greater cytotoxicity and genotoxicity than parent molecule, sulcotrione, and questions about the impact of photochemical process on environment. Adjuvants were shown to modify the biological features of pesticides. Addition of other elements, metals or biological products, can differently enhance cell toxicity of pesticides or electromagnetic radiations suggesting a synergy in living organisms. Electromagnetic fields spreading, pesticide by-products and mixtures monitoring become greater for environmental contamination evaluations.

  19. The electromagnetic field equations for moving media

    NASA Astrophysics Data System (ADS)

    Ivezić, T.

    2017-05-01

    In this paper a formulation of the field equation for moving media is developed by the generalization of an axiomatic geometric formulation of the electromagnetism in vacuum (Ivezić T 2005 Found. Phys. Lett. 18 401). First, the field equations with bivectors F (x) and ℳ(x) are presented and then these equations are written with the 4D vectors E(x), B(x), P (x) and M(x). The latter contain both the 4D velocity vector u of a moving medium and the 4D velocity vector v of the observers who measure E and B fields. They do not appear in previous literature. All these equations are also written in the standard basis and compared with Maxwell’s equations with 3D vectors. In this approach the Ampère-Maxwell law and Gauss’s law are inseparably connected in one law and the same happens with Faraday’s law and the law that expresses the absence of magnetic charge. It is shown that Maxwell’s equations with 3D vectors and the field equations with 4D geometric quantities are not equivalent in 4D spacetime

  20. Visualizing electromagnetic fields in metals by MRI

    NASA Astrophysics Data System (ADS)

    Chandrashekar, Chandrika Sefcikova; Shellikeri, Annadanesh; Chandrashekar, S.; Taylor, Erika A.; Taylor, Deanne M.

    2017-02-01

    Based upon Maxwell's equations, it has long been established that oscillating electromagnetic (EM) fields incident upon a metal surface, decay exponentially inside the conductor, leading to a virtual absence of EM fields at sufficient depths. Magnetic resonance imaging (MRI) utilizes radiofrequency (r.f.) EM fields to produce images. Here we present a visualization of a virtual EM vacuum inside a bulk metal strip by MRI, amongst several findings. At its simplest, an MRI image is an intensity map of density variations across voxels (pixels) of identical size (=Δ x Δ y Δ z ). By contrast in bulk metal MRI, we uncover that despite uniform density, intensity variations arise from differing effective elemental volumes (voxels) from different parts of the bulk metal. Further, we furnish chemical shift imaging (CSI) results that discriminate different faces (surfaces) of a metal block according to their distinct nuclear magnetic resonance (NMR) chemical shifts, which holds much promise for monitoring surface chemical reactions noninvasively. Bulk metals are ubiquitous, and MRI is a premier noninvasive diagnostic tool. Combining the two, the emerging field of bulk metal MRI can be expected to grow in importance. The findings here may impact further development of bulk metal MRI and CSI.

  1. Enhanced nonlinear susceptibility via double-double electromagnetically induced transparency

    NASA Astrophysics Data System (ADS)

    Alotaibi, Hessa M. M.; Sanders, Barry C.

    2016-11-01

    We investigate the nonlinear optical susceptibility of an alkali-metal atom with tripod electronic configuration responsible for generating cross-phase modulation and self-phase modulation under the condition of double-double electromagnetically induced transparency. Our investigation demonstrates an enhancement in the nonlinear optical susceptibility of an alkali-metal atom by a factor of 1000 in the region of the second transparency window. This enhancement is in comparison with the atom's susceptibility in the first transparency window for the same parameters under the same conditions. Nonlinear-absorption enhancement arises by canceling Raman-gain generation, which arises when the probe and signal fields have equal intensities. At the center of the second transparency window, we obtain the condition required to attain a nonvanishing nonlinear optical susceptibility. In the bare-state picture, the coupling field must be off resonant from a bare-to-bare-state transition, while working in the semiclassical dressed picture required the signal field to be tuned off resonantly with a bare-to-dressed-state transition. The relation that governs the values of coupling- and signal-field detuning are also obtained. Our scheme exhibits the fact that the second transparency window has advantages over the first transparency window with respect to obtaining an enhanced Kerr effect, and our calculation includes simulation of both low-temperature and Doppler-broadened regimes.

  2. Pulsed Electromagnetic Field Regulates MicroRNA 21 Expression to Activate TGF-β Signaling in Human Bone Marrow Stromal Cells to Enhance Osteoblast Differentiation

    PubMed Central

    Rifkin, Daniel; Dabovic, Branka

    2017-01-01

    Pulsed electromagnetic fields (PEMFs) have been documented to promote bone fracture healing in nonunions and increase lumbar spinal fusion rates. However, the molecular mechanisms by which PEMF stimulates differentiation of human bone marrow stromal cells (hBMSCs) into osteoblasts are not well understood. In this study the PEMF effects on hBMSCs were studied by microarray analysis. PEMF stimulation of hBMSCs' cell numbers mainly affected genes of cell cycle regulation, cell structure, and growth receptors or kinase pathways. In the differentiation and mineralization stages, PEMF regulated preosteoblast gene expression and notably, the transforming growth factor-beta (TGF-β) signaling pathway and microRNA 21 (miR21) were most highly regulated. PEMF stimulated activation of Smad2 and miR21-5p expression in differentiated osteoblasts, and TGF-β signaling was essential for PEMF stimulation of alkaline phosphatase mRNA expression. Smad7, an antagonist of the TGF-β signaling pathway, was found to be miR21-5p's putative target gene and PEMF caused a decrease in Smad7 expression. Expression of Runx2 was increased by PEMF treatment and the miR21-5p inhibitor prevented the PEMF stimulation of Runx2 expression in differentiating cells. Thus, PEMF could mediate its effects on bone metabolism by activation of the TGF-β signaling pathway and stimulation of expression of miR21-5p in hBMSCs. PMID:28512472

  3. Pulsed Electromagnetic Field Regulates MicroRNA 21 Expression to Activate TGF-β Signaling in Human Bone Marrow Stromal Cells to Enhance Osteoblast Differentiation.

    PubMed

    Selvamurugan, Nagarajan; He, Zhiming; Rifkin, Daniel; Dabovic, Branka; Partridge, Nicola C

    2017-01-01

    Pulsed electromagnetic fields (PEMFs) have been documented to promote bone fracture healing in nonunions and increase lumbar spinal fusion rates. However, the molecular mechanisms by which PEMF stimulates differentiation of human bone marrow stromal cells (hBMSCs) into osteoblasts are not well understood. In this study the PEMF effects on hBMSCs were studied by microarray analysis. PEMF stimulation of hBMSCs' cell numbers mainly affected genes of cell cycle regulation, cell structure, and growth receptors or kinase pathways. In the differentiation and mineralization stages, PEMF regulated preosteoblast gene expression and notably, the transforming growth factor-beta (TGF-β) signaling pathway and microRNA 21 (miR21) were most highly regulated. PEMF stimulated activation of Smad2 and miR21-5p expression in differentiated osteoblasts, and TGF-β signaling was essential for PEMF stimulation of alkaline phosphatase mRNA expression. Smad7, an antagonist of the TGF-β signaling pathway, was found to be miR21-5p's putative target gene and PEMF caused a decrease in Smad7 expression. Expression of Runx2 was increased by PEMF treatment and the miR21-5p inhibitor prevented the PEMF stimulation of Runx2 expression in differentiating cells. Thus, PEMF could mediate its effects on bone metabolism by activation of the TGF-β signaling pathway and stimulation of expression of miR21-5p in hBMSCs.

  4. Inelastic deformation of conductive bodies in electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Altenbach, Holm; Morachkovsky, Oleg; Naumenko, Konstantin; Lavinsky, Denis

    2016-09-01

    Inelastic deformation of conductive bodies under the action of electromagnetic fields is analyzed. Governing equations for non-stationary electromagnetic field propagation and elastic-plastic deformation are presented. The variational principle of minimum of the total energy is applied to formulate the numerical solution procedure by the finite element method. With the proposed method, distributions of vector characteristics of the electromagnetic field and tensor characteristics of the deformation process are illustrated for the inductor-workpiece system within a realistic electromagnetic forming process.

  5. Mortality in workers exposed to electromagnetic fields.

    PubMed Central

    Milham, S

    1985-01-01

    In an occupational mortality analysis of 486,000 adult male death records filed in Washington State in the years 1950-1982, leukemia and the non-Hodgkin's lymphomas show increased proportionate mortality ratios (PMRs) in workers employed in occupations with intuitive exposures to electromagnetic fields. Nine occupations of 219 were considered to have electric or magnetic field exposures. These were: electrical and electronic technicians, radio and telegraph operators, radio and television repairmen, telephone and power linemen, power station operators, welders, aluminum reduction workers, motion picture projectionists and electricians. There were 12,714 total deaths in these occupations. Eight of the nine occupations had PMR increases for leukemia [International Classification of Diseases (ICD), seventh revision 204] and seven of the nine occupations had PMR increases for the other lymphoma category (7th ICD 200.2, 202). The highest PMRs were seen for acute leukemia: (67 deaths observed, 41 deaths expected; PMR 162), and in the other lymphomas (51 deaths observed, 31 deaths expected; PMR 164). No increase in mortality was seen for Hodgkin's disease or multiple myeloma. These findings offer some support for the hypothesis that electric and magnetic fields may be carcinogenic. PMID:4085433

  6. Mortality in workers exposed to electromagnetic fields

    SciTech Connect

    Milham, S. Jr.

    1985-10-01

    In an occupational mortality analysis of 486,000 adult male death records filed in Washington State in the years 1950-1982, leukemia and the non-Hodgkin's lymphomas show increased proportionate mortality ratios (PMRs) in workers employed in occupations with intuitive exposures to electromagnetic fields. Nine occupations of 219 were considered to have electric or magnetic field exposures. These were: electrical and electronic technicians, radio and telegraph operators, radio and television repairmen, telephone and power linemen, power station operators, welders, aluminum reduction workers, motion picture projectionists and electricians. There were 12,714 total deaths in these occupations. Eight of the nine occupations had PMR increases for leukemia (International Classification of Diseases (ICD), seventh revision 204) and seven of the nine occupations had PMR increases for the other lymphoma category (7th ICD 200.2, 202). The highest PMRs were seen for acute leukemia: (67 deaths observed, 41 deaths expected; PMR 162), and in the other lymphomas (51 deaths observed, 31 deaths expected; PMR 164). No increase in mortality was seen for Hodgkin's disease or multiple myeloma. These findings offer some support for the hypothesis that electric and magnetic fields may be carcinogenic.

  7. Electromagnetic polarizabilities: Lattice QCD in background fields

    SciTech Connect

    W. Detmold, B.C. Tiburzi, A. Walker-Loud

    2012-04-01

    Chiral perturbation theory makes definitive predictions for the extrinsic behavior of hadrons in external electric and magnetic fields. Near the chiral limit, the electric and magnetic polarizabilities of pions, kaons, and nucleons are determined in terms of a few well-known parameters. In this limit, hadrons become quantum mechanically diffuse as polarizabilities scale with the inverse square-root of the quark mass. In some cases, however, such predictions from chiral perturbation theory have not compared well with experimental data. Ultimately we must turn to first principles numerical simulations of QCD to determine properties of hadrons, and confront the predictions of chiral perturbation theory. To address the electromagnetic polarizabilities, we utilize the background field technique. Restricting our attention to calculations in background electric fields, we demonstrate new techniques to determine electric polarizabilities and baryon magnetic moments for both charged and neutral states. As we can study the quark mass dependence of observables with lattice QCD, the lattice will provide a crucial test of our understanding of low-energy QCD, which will be timely in light of ongoing experiments, such as at COMPASS and HI gamma S.

  8. Electromagnetic fields and male breast cancer.

    PubMed

    Tynes, T

    1993-01-01

    The aetiology of male breast cancer is still considered to be rather unclear. Epidemiological studies have recently shown an excess risk of male breast cancer in "electrical workers" with potential exposure to electromagnetic (EM) fields. Interest on the possible association between pineal function and breast cancer has come into focus. The pineal hormone melatonin has been shown to reduce the incidence of experimentally-induced breast cancer in rats, the hormone is oncostatic and cytotoxic to breast, ovarian, and bladder cancer cell lines in vitro. Treatment of cancer patients with orally administered melatonin has been tried. Pineal function in humans is suppressed by light-at-night (LAN). Animal studies have shown that exposure to 60-Hz electric fields may also suppress the nocturnal rise in pineal melatonin production in adult rats. Breast cancer is the leading cause of cancer death among women in industrialised world. No good explanation has so far been provided for the increased incidence of this site during the last decades, although changes in fertility factors have had some effect. If new epidemiological and experimental data give support to the hypothesis that exposure to LAN and EM fields may increase breast cancer risk, this may have regulatory and political consequences for future use of electric power.

  9. Electromagnetic field at finite temperature: A first order approach

    NASA Astrophysics Data System (ADS)

    Casana, R.; Pimentel, B. M.; Valverde, J. S.

    2006-10-01

    In this work we study the electromagnetic field at finite temperature via the massless DKP formalism. The constraint analysis is performed and the partition function for the theory is constructed and computed. When it is specialized to the spin 1 sector we obtain the well-known result for the thermodynamic equilibrium of the electromagnetic field.

  10. Sensing network for electromagnetic fields generated by seismic activities

    NASA Astrophysics Data System (ADS)

    Gershenzon, Naum I.; Bambakidis, Gust; Ternovskiy, Igor V.

    2014-06-01

    The sensors network is becoming prolific and play now increasingly more important role in acquiring and processing information. Cyber-Physical Systems are focusing on investigation of integrated systems that includes sensing, networking, and computations. The physics of the seismic measurement and electromagnetic field measurement requires special consideration how to design electromagnetic field measurement networks for both research and detection earthquakes and explosions along with the seismic measurement networks. In addition, the electromagnetic sensor network itself could be designed and deployed, as a research tool with great deal of flexibility, the placement of the measuring nodes must be design based on systematic analysis of the seismic-electromagnetic interaction. In this article, we review the observations of the co-seismic electromagnetic field generated by earthquakes and man-made sources such as vibrations and explosions. The theoretical investigation allows the distribution of sensor nodes to be optimized and could be used to support existing geological networks. The placement of sensor nodes have to be determined based on physics of electromagnetic field distribution above the ground level. The results of theoretical investigations of seismo-electromagnetic phenomena are considered in Section I. First, we compare the relative contribution of various types of mechano-electromagnetic mechanisms and then analyze in detail the calculation of electromagnetic fields generated by piezomagnetic and electrokinetic effects.

  11. Assessment of Electromagnetic Fields at NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Ficklen, Carter B.

    1995-01-01

    This report presents the results of an assessment of ElectroMagnetic Fields (EMF) completed at NASA Langley Research Center as part of the Langley Aerospace Research Summer Scholars Program. This project was performed to determine levels of electromagnetic fields, determine the significance of the levels present, and determine a plan to reduce electromagnetic field exposure, if necessary. This report also describes the properties of electromagnetic fields and their interaction with humans. The results of three major occupational epidemiological studies is presented to determine risks posed to humans by EMF exposure. The data for this report came from peer-reviewed journal articles and government publications pertaining to the health effects of electromagnetic fields.

  12. Fluxes of electromagnetic field energy in HTSC transformers

    NASA Astrophysics Data System (ADS)

    Volkov, E. P.; Dzhafarov, E. A.

    2016-12-01

    The transfer of electric power in an HTSC electromagnetic system is considered using the Poynting vector. An analysis of the process of transfer of electromagnetic field energy in HTSC transformers with and without an iron core is given. It is shown that the power of an HTSC transformer increases when its magnetic core is made from amorphous electrical steel. Schemes of HTSC transformers with a localized magnetic field are given with cylindrical and disk symmetrical interleaved windings providing the cost-saving process of transfer of large electromagnetic energy at a high degree of its uniformity and improve the factor of nonuniformity of electromagnetic flux density.

  13. Electromagnetic Fields, Oxidative Stress, and Neurodegeneration

    PubMed Central

    Consales, Claudia; Merla, Caterina; Marino, Carmela; Benassi, Barbara

    2012-01-01

    Electromagnetic fields (EMFs) originating both from both natural and manmade sources permeate our environment. As people are continuously exposed to EMFs in everyday life, it is a matter of great debate whether they can be harmful to human health. On the basis of two decades of epidemiological studies, an increased risk for childhood leukemia associated with Extremely Low Frequency fields has been consistently assessed, inducing the International Agency for Research on Cancer to insert them in the 2B section of carcinogens in 2001. EMFs interaction with biological systems may cause oxidative stress under certain circumstances. Since free radicals are essential for brain physiological processes and pathological degeneration, research focusing on the possible influence of the EMFs-driven oxidative stress is still in progress, especially in the light of recent studies suggesting that EMFs may contribute to the etiology of neurodegenerative disorders. This review synthesizes the emerging evidences about this topic, highlighting the wide data uncertainty that still characterizes the EMFs effect on oxidative stress modulation, as both pro-oxidant and neuroprotective effects have been documented. Care should be taken to avoid methodological limitations and to determine the patho-physiological relevance of any alteration found in EMFs-exposed biological system. PMID:22991514

  14. Influence of electromagnetic field on soliton-mediated charge transport in biological systems.

    PubMed

    Brizhik, Larissa

    2015-01-01

    It is shown that electromagnetic fields affect dynamics of Davydov's solitons which provide charge transport processes in macromolecules during metabolism of the system. There is a resonant frequency of the field at which it can cause the transition of electrons from bound soliton states into delocalised states. Such decay of solitons reduces the effectiveness of charge transport, and, therefore, inhibits redox processes. Solitons radiate their own electromagnetic field of characteristic frequency determined by their average velocity. This self-radiated field leads to synchronization of soliton dynamics and charge transport processes, and is the source of the coherence in the system. Exposition of the system to the oscillating electromagnetic field of the frequency, which coincides with the eigen-frequency of solitons can enhance eigen-radiation of solitons, and, therefore, will enhance synchronization of charge transpor, stimulate the redox processes and increase coherence in the system. Electromagnetic oscillating field causes also ratchet phenomenon of solitons, i.e., drift of solitons in macromolecules in the presence of unbiased periodic field. Such additional drift enhances the charge transport processes. It is shown that temperature facilitates the ratchet drift. In particular, temperature fluctuations lead to the lowering of the critical value of the intensity and period of the field, above which the drift of solitons takes place. Moreover, there is a stochastic resonance in the soliton dynamics in external electromagnetic fields. This means, that there is some optimal temperature at which the drift of solitons is maximal.

  15. Acute neuroprotective effects of extremely low-frequency electromagnetic fields after traumatic brain injury in rats.

    PubMed

    Yang, Yang; Li, Ling; Wang, Yan-Gang; Fei, Zhou; Zhong, Jun; Wei, Li-Zhou; Long, Qian-Fa; Liu, Wei-Ping

    2012-05-10

    Traumatic brain injury commonly has a result of a short window of opportunity between the period of initial brain injury and secondary brain injury, which provides protective strategies and can reduce damages of brain due to secondary brain injury. Previous studies have reported neuroprotective effects of extremely low-frequency electromagnetic fields. However, the effects of extremely low-frequency electromagnetic fields on neural damage after traumatic brain injury have not been reported yet. The present study aims to investigate effects of extremely low-frequency electromagnetic fields on neuroprotection after traumatic brain injury. Male Sprague-Dawley rats were used for the model of lateral fluid percussion injury, which were placed in non-electromagnetic fields and 15 Hz (Hertz) electromagnetic fields with intensities of 1 G (Gauss), 3 G and 5 G. At various time points (ranging from 0.5 to 30 h) after lateral fluid percussion injury, rats were treated with kainic acid (administered by intraperitoneal injection) to induce apoptosis in hippocampal cells. The results were as follows: (1) the expression of hypoxia-inducible factor-1α was dramatically decreased during the neuroprotective time window. (2) The kainic acid-induced apoptosis in the hippocampus was significantly decreased in rats exposed to electromagnetic fields. (3) Electromagnetic fields exposure shortened the escape time in water maze test. (4) Electromagnetic fields exposure accelerated the recovery of the blood-brain barrier after brain injury. These findings revealed that extremely low-frequency electromagnetic fields significantly prolong the window of opportunity for brain protection and enhance the intensity of neuroprotection after traumatic brain injury. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

  16. 78 FR 33654 - Reassessment of Exposure to Radiofrequency Electromagnetic Fields Limits and Policies

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-06-04

    ... Electromagnetic Fields Limits and Policies AGENCY: Federal Communications Commission. ACTION: Proposed rule... electromagnetic fields. The Commission's further proposals reflect an effort to provide more efficient, practical... RF electromagnetic fields. The Commission underscores that in conducting this review it will...

  17. Surface-enhanced Raman spectroscopy of double-shell hollow nanoparticles: electromagnetic and chemical enhancements.

    PubMed

    Mahmoud, Mahmoud A

    2013-05-28

    Enhancements of the Raman signal by the newly prepared gold-palladium and gold-platinum double-shell hollow nanoparticles were examined and compared with those using gold nanocages (AuNCs). The surface-enhanced Raman spectra (SERS) of thiophenol adsorbed on the surface of AuNCs assembled into a Langmuir-Blodgett monolayer were 10-fold stronger than AuNCs with an inner Pt or Pd shell. The chemical and electromagnetic enhancement mechanisms for these hollow nanoparticles were further proved by comparing the Raman enhancement of nitrothiophenol and nitrotoulene. Nitrothiophenol binds to the surface of the nanoparticles by covalent interaction, and Raman enhancement by both the two mechanisms is possible, while nitrotoulene does not form any chemical bond with the surface of the nanoparticles and hence no chemical enhancement is expected. Based on discrete dipole approximation (DDA) calculations and the experimental SERS results, AuNCs introduced a high electromagnetic enhancement, while the nanocages with inner Pt or Pd shell have a strong chemical enhancement. The optical measurements of the localized surface plasmon resonance (LSPR) of the nanocages with an outer Au shell and an inner Pt or Pd shell were found, experimentally and theoretically, to be broad compared with AuNCs. The possible reason could be due to the decrease of the coherence time of Au oscillated free electrons and fast damping of the plasmon energy. This agreed well with the fact that a Pt or Pd inner nanoshell decreases the electromagnetic field of the outer Au nanoshell while increasing the SERS chemical enhancement.

  18. Interpreting marine controlled source electromagnetic field behaviour with streamlines

    NASA Astrophysics Data System (ADS)

    Pethick, A. M.; Harris, B. D.

    2013-10-01

    Streamlines represent particle motion within a vector field as a single line structure and have been used in many areas of geophysics. We extend the concept of streamlines to interactive three dimensional representations of the coupled vector fields generated during marine controlled source electromagnetic surveys. These vector fields have measurable amplitudes throughout many hundreds of cubic kilometres. Electromagnetic streamline representation makes electromagnetic interactions within complex geo-electrical setting comprehensible. We develop an interface to rapidly compute and interactively visualise the electric and magnetic fields as streamlines for 3D marine controlled source electromagnetic surveys. Several examples highlighting how interactive use has value in marine controlled source electromagnetic survey design, interpretation and teaching are provided. The first videos of electric, magnetic and Poynting vector field streamlines are provided along with the first published example of the airwave represented as streamlines. We demonstrate that the electric field airwave is a circulating vortex moving down and out from the air-water interface towards the ocean floor. The use of interactive streamlines is not limited to marine controlled source electromagnetic methods. Streamlines provides a high level visualisation tool for interpreting the electric and magnetic field behaviour generated by a wide range of electromagnetic survey configurations for complex 3D geo-electrical settings.

  19. [Dynamics of biomacromolecules in coherent electromagnetic radiation field].

    PubMed

    Leshcheniuk, N S; Apanasevich, E E; Tereshenkov, V I

    2014-01-01

    It is shown that induced oscillations and periodic displacements of the equilibrium positions occur in biomacromolecules in the absence of electromagnetic radiation absorption, due to modulation of interaction potential between atoms and groups of atoms forming the non-valence bonds in macromolecules by the external electromagnetic field. Such "hyperoscillation" state causes inevitably the changes in biochemical properties of macromolecules and conformational transformation times.

  20. An experiment to study strong electromagnetic fields at RHIC

    SciTech Connect

    Fatyga, M. ); Norbury, J.W. . Dept. of Physics)

    1990-01-01

    We present a description of an experiment which can be used to search for effects of strong electromagnetic fields on the production of e{sup +}e{sup {minus}} pairs in the elastic scattering of two heavy ions at RHIC. A very brief discussion of other possible studies of electromagnetic phenomena at RHIC is also presented.

  1. The van Cittert-Zernike theorem for electromagnetic fields.

    PubMed

    Ostrovsky, Andrey S; Martínez-Niconoff, Gabriel; Martínez-Vara, Patricia; Olvera-Santamaría, Miguel A

    2009-02-02

    The van Cittert-Zernike theorem, well known for the scalar optical fields, is generalized for the case of vector electromagnetic fields. The deduced theorem shows that the degree of coherence of the electromagnetic field produced by the completely incoherent vector source increases on propagation whereas the degree of polarization remains unchanged. The possible application of the deduced theorem is illustrated by an example of optical simulation of partially coherent and partially polarized secondary source with the controlled statistical properties.

  2. Electromagnetic theories of surface-enhanced Raman spectroscopy.

    PubMed

    Ding, Song-Yuan; You, En-Ming; Tian, Zhong-Qun; Moskovits, Martin

    2017-07-07

    Surface-enhanced Raman spectroscopy (SERS) and related spectroscopies are powered primarily by the concentration of the electromagnetic (EM) fields associated with light in or near appropriately nanostructured electrically-conducting materials, most prominently, but not exclusively high-conductivity metals such as silver and gold. This field concentration takes place on account of the excitation of surface-plasmon (SP) resonances in the nanostructured conductor. Optimizing nanostructures for SERS, therefore, implies optimizing the ability of plasmonic nanostructures to concentrate EM optical fields at locations where molecules of interest reside, and to enhance the radiation efficiency of the oscillating dipoles associated with these molecules and nanostructures. This review summarizes the development of theories over the past four decades pertinent to SERS, especially those contributing to our current understanding of SP-related SERS. Special emphasis is given to the salient strategies and theoretical approaches for optimizing nanostructures with hotspots as efficient EM near-field concentrating and far-field radiating substrates for SERS. A simple model is described in terms of which the upper limit of the SERS enhancement can be estimated. Several experimental strategies that may allow one to approach, or possibly exceed this limit, such as cascading the enhancement of the local and radiated EM field by the multiscale EM coupling of hierarchical structures, and generating hotspots by hybridizing an antenna mode with a plasmonic waveguide cavity mode, which would result in an increased local field enhancement, are discussed. Aiming to significantly broaden the application of SERS to other fields, and especially to material science, we consider hybrid structures of plasmonic nanostructures and other material phases and strategies for producing strong local EM fields at desired locations in such hybrid structures. In this vein, we consider some of the numerical

  3. Algebraic structure of general electromagnetic fields and energy flow

    SciTech Connect

    Hacyan, Shahen

    2011-08-15

    Highlights: > Algebraic structure of general electromagnetic fields in stationary spacetime. > Eigenvalues and eigenvectors of the electomagnetic field tensor. > Energy-momentum in terms of eigenvectors and Killing vector. > Explicit form of reference frame with vanishing Poynting vector. > Application of formalism to Bessel beams. - Abstract: The algebraic structures of a general electromagnetic field and its energy-momentum tensor in a stationary space-time are analyzed. The explicit form of the reference frame in which the energy of the field appears at rest is obtained in terms of the eigenvectors of the electromagnetic tensor and the existing Killing vector. The case of a stationary electromagnetic field is also studied and a comparison is made with the standard short-wave approximation. The results can be applied to the general case of a structured light beams, in flat or curved spaces. Bessel beams are worked out as example.

  4. Reflection and refraction of the electromagnetic field in a semi-infinite plasma

    NASA Astrophysics Data System (ADS)

    Apostol, M.; Vaman, G.

    2009-11-01

    We compute the reflected and refracted electromagnetic fields for an ideal semi-infinite (half-space) plasma, as well as the reflection coefficient, by using a general procedure based on equations of motion and electromagnetic potentials. The approach consists of representing the charge disturbances by a displacement field in the positions of the moving particles (electrons). The propagation of an electromagnetic wave in plasma is treated by means of the retarded electromagnetic potentials, and the resulting integral equations are solved. Generalized Fresnel's relations are thereby obtained for any incidence angle and polarization and the angles of total polarization and total reflection are derived. Bulk and surface plasmon-polariton modes are identified. As it is well known, the field inside the plasma is either damped (evanescent) or propagating (transparency regime), and the reflection coefficient exhibits an abrupt enhancement on passing from the propagating regime to the damped one (total reflection).

  5. [Electromagnetic fields in melting divisions of nickel production].

    PubMed

    Nikitina, V N; Liashko, G G; Nikanov, A N; Nikitina, N Iu

    2004-01-01

    The authors evaluated electromagnetic situation in melting divisions, on transformer substation. Studies covered alternating electric and magnetic fields of industrial frequencies and direct magnetic fields in fire mode of nickel production on workplaces during working shifts. Results proved that induction of the magnetic fields varies widely. Magnetic fields influence is accidental and remains additional factor affecting human body.

  6. [Computational radiofrequency electromagnetic field dosimetry in evaluation of biological effects].

    PubMed

    Perov, S Iu; Kudryashov, Iu B; Rubtsova, N B

    2012-01-01

    Given growing computational resources, radiofrequency electromagnetic field dosimetry is becoming more vital in the study of biological effects of non-ionizing electromagnetic radiation. The study analyzes numerical methods which are used in theoretical dosimetry to assess the exposure level and specific absorption rate distribution. The advances of theoretical dosimetry are shown. Advantages and disadvantages of different methods are analyzed in respect to electromagnetic field biological effects. The finite-difference time-domain method was implemented in detail; also evaluated were possible uncertainties of complex biological structure simulation for bioelectromagnetic investigations.

  7. Effects of Electromagnetic Fields on Fish and Invertebrates

    SciTech Connect

    Schultz, Irvin R.; Woodruff, Dana L.; Marshall, Kathryn E.; Pratt, William J.; Roesijadi, Guritno

    2010-10-13

    In this progress report, we describe the preliminary experiments conducted with three fish and one invertebrate species to determine the effects of exposure to electromagnetic fields. During fiscal year 2010, experiments were conducted with coho salmon (Onchrohychus kisutch), California halibut (Paralicthys californicus), Atlantic halibut (Hippoglossus hippoglossus), and Dungeness crab (Cancer magister). The work described supports Task 2.1.3: Effects on Aquatic Organisms, Subtask 2.1.3.1: Electromagnetic Fields.

  8. [Pulsed electromagnetic fields (PEMF)--results in evidence based medicine].

    PubMed

    Pieber, Karin; Schuhfried, Othmar; Fialka-Moser, Veronika

    2007-01-01

    Therapy with electromagnetic fields has a very old tradition in medicine. The indications are widespread, whereas little is known about the effects. Controlled randomizied studies with positive results for pulsed electromagnetic fields (PEMF) are available for osteotomies, the healing of skin wounds, and osteoarthritis. Comparison of the studies is difficult because of the different doses applied and intervals of therapy. Therefore recommendations regarding an optimal dosis and interval are, depending on the disease, quite variable.

  9. Electromagnetic field-induced stimulation of Bruton's tyrosine kinase.

    PubMed

    Kristupaitis, D; Dibirdik, I; Vassilev, A; Mahajan, S; Kurosaki, T; Chu, A; Tuel-Ahlgren, L; Tuong, D; Pond, D; Luben, R; Uckun, F M

    1998-05-15

    Here we present evidence that exposure of DT40 lymphoma B-cells to low energy electromagnetic fields (EMF) results in activation of phospholipase C-gamma 2 (PLC-gamma2), leading to increased inositol phospholipid turnover. PLC-gamma2 activation in EMF-stimulated cells is mediated by stimulation of the Bruton's tyrosine kinase (BTK), a member of the Src-related TEC family of protein tyrosine kinases, which acts downstream of LYN kinase and upstream of PLC-gamma2. B-cells rendered BTK-deficient by targeted disruption of the btk gene did not show enhanced PLC-gamma2 activation in response to EMF exposure. Introduction of the wild-type (but not a kinase domain mutant) human btk gene into BTK-deficient B-cells restored their EMF responsiveness. Thus, BTK exerts a pivotal and mandatory function in initiation of EMF-induced signaling cascades in B-cells.

  10. Electromagnetic fields and potentials generated by massless charged particles

    SciTech Connect

    Azzurli, Francesco; Lechner, Kurt

    2014-10-15

    We provide for the first time the exact solution of Maxwell’s equations for a massless charged particle moving on a generic trajectory at the speed of light. In particular we furnish explicit expressions for the vector potential and the electromagnetic field, which were both previously unknown, finding that they entail different physical features for bounded and unbounded trajectories. With respect to the standard Liénard–Wiechert field the electromagnetic field acquires singular δ-like contributions whose support and dimensionality depend crucially on whether the motion is (a) linear, (b) accelerated unbounded, (c) accelerated bounded. In the first two cases the particle generates a planar shock-wave-like electromagnetic field traveling along a straight line. In the second and third cases the field acquires, in addition, a δ-like contribution supported on a physical singularity-string attached to the particle. For generic accelerated motions a genuine radiation field is also present, represented by a regular principal-part type distribution diverging on the same singularity-string. - Highlights: • First exact solution of Maxwell’s equations for massless charges in arbitrary motion. • Explicit expressions of electromagnetic fields and potentials. • Derivations are rigorous and based on distribution theory. • The form of the field depends heavily on whether the motion is bounded or unbounded. • The electromagnetic field contains unexpected Dirac-delta-function contributions.

  11. Biological effects of prolonged exposure to ELF electromagnetic fields in rats: III. 50 Hz electromagnetic fields.

    PubMed

    Zecca, L; Mantegazza, C; Margonato, V; Cerretelli, P; Caniatti, M; Piva, F; Dondi, D; Hagino, N

    1998-01-01

    Groups of adult male Sprague Dawley rats (64 rats each) were exposed for 8 months to electromagnetic fields (EMF) of two different field strength combinations: 5microT - 1kV/m and 100microT - 5kV/m. A third group was sham exposed. Field exposure was 8 hrs/day for 5 days/week. Blood samples were collected for hematology determinations before the onset of exposure and at 12 week intervals. At sacrifice, liver, heart, mesenteric lymph nodes, bone marrow, and testes were collected for morphology and histology assessments, while the pineal gland and brain were collected for biochemical determinations. At both field strength combinations, no pathological changes were observed in animal growth rate, in morphology and histology of the collected tissue specimens (liver, heart, mesenteric lymph nodes, testes, bone marrow), and in serum chemistry. An increase in norepinephrine levels occurred in the pineal gland of rats exposed to the higher field strength. The major changes in the brain involved the opioid system in frontal cortex, parietal cortex, and hippocampus. From the present findings it may be hypothesized that EMF may cause alteration of some brain functions.

  12. [The influence of electromagnetic fields on flora and fauna].

    PubMed

    Rochalska, Małgorzata

    2009-01-01

    This paper presents the influence of natural and artificial electromagnetic fields (EMF) on fauna and flora. The mechanisms of Earth's magnetic field detection and the use of this skill by migratory animals to faultlessly reach the destination of their travel are discussed, as well as the positive effects of electric and magnetic fields on plants relative to their physiology, yielding and health. EMF influence on social insects and animal organisms, including possible DNA damages and DNA repair systems, is presented. The influence of high frequency electromagnetic fields on birds nesting is also discussed.

  13. Nonlinear electromagnetic fields as a source of universe acceleration

    NASA Astrophysics Data System (ADS)

    Kruglov, S. I.

    2016-04-01

    A model of nonlinear electromagnetic fields with a dimensional parameter β is proposed. From PVLAS experiment the bound on the parameter β was obtained. Electromagnetic fields are coupled with the gravitation field and we show that the universe accelerates due to nonlinear electromagnetic fields. The magnetic universe is considered and the stochastic magnetic field is a background. After inflation the universe decelerates and approaches to the radiation era. The range of the scale factor, when the causality of the model and a classical stability take place, was obtained. The spectral index, the tensor-to-scalar ratio, and the running of the spectral index were estimated which are in approximate agreement with the Planck, WMAP, and BICEP2 data.

  14. Basic Materials for Electromagnetic Field Standards

    DTIC Science & Technology

    2003-03-04

    choliner- gic processes // Labor Hygiene and Biological Effects of electromagnetic waves of ra- diofrequencies. Proceedings of 3rd All-Union Symposium...Microwave on Blood asparthate Amine transferase Enzymatic System. J. Radiation biology and ecol - ogy (Russian academy of sciences) 2001. Vol. 41. No.1...under Increased Temperature. J. Radiation biology and ecol - ogy (Russian academy of sciences) 2002. Vol. 42. No.1, pp. 191–193. 13. T.P. Semenova

  15. Electromagnetic fluid drift turbulence in static ergodic magnetic fields

    SciTech Connect

    Reiser, D.; Scott, B.

    2005-12-15

    Numerical simulations of three-dimensional nonlinear electromagnetic fluid drift turbulence in a tokamak plasma with externally applied stochastic magnetic-field perturbations are presented. The contributions to the radial particle transport due to nonlinearities arising from ExB advection and magnetic flutter are investigated for perturbation fields of varying strengths in the cases of low and high collisionalities. The perturbation strength is varied to study the physics for Chirikov parameters above 1. In all the cases considered a significant increase of ExB transport is found. A static contribution in the density and velocity perturbations contributes significantly to the total radial ExB transport. For low collisionality, the external perturbation leads to enhanced density and velocity fluctuations over a broad range in the toroidal wave-number spectrum, resulting in an enhanced turbulent flux. For high collisionality, the density fluctuations stay roughly the same and the velocity fluctuations are increased in an intermediate range of the toroidal wave number spectrum, separated from the maximum of the density fluctuations, thus leaving the turbulent flux almost unchanged.

  16. Electromagnetic fluid drift turbulence in static ergodic magnetic fields

    NASA Astrophysics Data System (ADS)

    Reiser, D.; Scott, B.

    2005-12-01

    Numerical simulations of three-dimensional nonlinear electromagnetic fluid drift turbulence in a tokamak plasma with externally applied stochastic magnetic-field perturbations are presented. The contributions to the radial particle transport due to nonlinearities arising from E ×B advection and magnetic flutter are investigated for perturbation fields of varying strengths in the cases of low and high collisionalities. The perturbation strength is varied to study the physics for Chirikov parameters above 1. In all the cases considered a significant increase of E ×B transport is found. A static contribution in the density and velocity perturbations contributes significantly to the total radial E ×B transport. For low collisionality, the external perturbation leads to enhanced density and velocity fluctuations over a broad range in the toroidal wave-number spectrum, resulting in an enhanced turbulent flux. For high collisionality, the density fluctuations stay roughly the same and the velocity fluctuations are increased in an intermediate range of the toroidal wave number spectrum, separated from the maximum of the density fluctuations, thus leaving the turbulent flux almost unchanged.

  17. MESA: a new configuration for measuring electromagnetic field fluctuations.

    PubMed

    Harte, T M; Black, D L; Hollinshead, M T

    1999-11-01

    This paper describes how the multi-energy sensor array has been refitted to meet the needs of measuring geomagnetic and other types of electromagnetic phenomena in an environment. This portable laptop computer system was designed to measure the interaction of multiple frequencies with the psychological and physiological processes that underlie human exposure to electromagnetic fields across the spectra. New sensors and analytical software have been implemented in the new configuration.

  18. Resolving the electromagnetic mechanism of surface-enhanced light scattering at single hot spots

    PubMed Central

    Alonso-González, P.; Albella, P.; Schnell, M.; Chen, J.; Huth, F.; García-Etxarri, A.; Casanova, F.; Golmar, F.; Arzubiaga, L.; Hueso, L.E.; Aizpurua, J.; Hillenbrand, R.

    2012-01-01

    Light scattering at nanoparticles and molecules can be dramatically enhanced in the 'hot spots' of optical antennas, where the incident light is highly concentrated. Although this effect is widely applied in surface-enhanced optical sensing, spectroscopy and microscopy, the underlying electromagnetic mechanism of the signal enhancement is challenging to trace experimentally. Here we study elastically scattered light from an individual object located in the well-defined hot spot of single antennas, as a new approach to resolve the role of the antenna in the scattering process. We provide experimental evidence that the intensity elastically scattered off the object scales with the fourth power of the local field enhancement provided by the antenna, and that the underlying electromagnetic mechanism is identical to the one commonly accepted in surface-enhanced Raman scattering. We also measure the phase shift of the scattered light, which provides a novel and unambiguous fingerprint of surface-enhanced light scattering. PMID:22353715

  19. Suppression and control of leakage field in electromagnetic helical microwiggler

    SciTech Connect

    Ohigashi, N.; Tsunawaki, Y.; Imasaki, K.

    1995-12-31

    Shortening the period of electromagnetic wiggler introduces both the radical increase of the leakage field and the decrease of the field in the gap region. The leakage field is severer problem in planar electromagnetic wiggler than in helical wiggler. Hence, in order to develop a short period electromagnetic wiggler, we have adopted {open_quotes}three poles per period{close_quotes} type electromagnetic helical microwiggler. In this work, we inserted the permanent magnet (PM) blocks with specific magnetized directions in the space between magnetic poles, for suppressing the leakage field flowing out from a pole face to the neighboring pole face. These PM-blocks must have higher intrinsic coersive force than saturation field of pole material. The gap field due to each pole is adjustable by controlling the leakage fields, that is, controlling the position of each iron screw set in each retainer fixing the PM-blocks. At present time, a test wiggler with period 7.8mm, periodical number 10 and gap length 4.6mm has been manufactured. Because the ratio of PM-block aperture to gap length is important parameter to suppress the leakage field, the parameter has been surveyed experimentally for PM-blocks with several dimensions of aperture. The field strength of 3-5kG (K=0.2-0.4) would be expected in the wiggler.

  20. Analytical model for electromagnetic cascades in rotating electric field

    SciTech Connect

    Nerush, E. N.; Bashmakov, V. F.; Kostyukov, I. Yu.

    2011-08-15

    Electromagnetic cascades attract a lot of attention as an important quantum electrodynamics effect that will reveal itself in various electromagnetic field configurations at ultrahigh intensities. We study cascade dynamics in rotating electric field analytically and numerically. The kinetic equations for the electron-positron plasma and gamma-quanta are formulated. The scaling laws are derived and analyzed. For the cascades arising far above the threshold the dependence of the cascade parameters on the field frequency is derived. The spectra of high-energy cascade particles are calculated. The analytical results are verified by numerical simulations.

  1. Electromagnetic Fields Produced by Inclined Return Stroke Channel

    NASA Astrophysics Data System (ADS)

    Nemamcha, Abdelmalek; Houabes, Mourad

    2014-05-01

    In this paper further theoretical investigations to understand and elucidate recently raised questions on the characteristics of lightning return-strokes curried out. Using Antenna Theory (AT) model, which is extended to take into account the channel inclination, the electromagnetic fields expressions for vertical dipole are completed, and an inclined channel is properly modeled, vertical electric and azimuthally magnetic fields are computed at different distances (close, intermediate and far distance ranges). The computations show that amplitudes and wave forms of the electromagnetic fields at close and intermediate lightning environment are considerably affected by the channel inclination.

  2. Electromagnetic homeostasis and the role of low-amplitude electromagnetic fields on life organization.

    PubMed

    De Ninno, Antonella; Pregnolato, Massimo

    2017-01-01

    The appearance of endogenous electromagnetic fields in biological systems is a widely debated issue in modern science. The electrophysiological fields have very tiny intensities and it can be inferred that they are rapidly decreasing with the distance from the generating structure, vanishing at very short distances. This makes very hard their detection using standard experimental methods. However, the existence of fast-moving charged particles in the macromolecules inside both intracellular and extracellular fluids may envisage the generation of localized electric currents as well as the presence of closed loops, which implies the existence of magnetic fields. Moreover, the whole set of oscillatory frequencies of various substances, enzymes, cell membranes, nucleic acids, bioelectrical phenomena generated by the electrical rhythm of coherent groups of cells, cell-to-cell communication among population of host bacteria, forms the increasingly complex hierarchies of electromagnetic signals of different frequencies which cover the living being and represent a fundamental information network controlling the cell metabolism. From this approach emerges the concept of electromagnetic homeostasis: that is, the capability of the human body to maintain the balance of highly complex electromagnetic interactions within, in spite of the external electromagnetic noisy environment. This concept may have an important impact on the actual definitions of heal and disease.

  3. [Development of innovative methods of electromagnetic field evaluation for portable radio-station].

    PubMed

    Rubtsova, N B; Perov, S Iu; Bogacheva, E V; Kuster, N

    2013-01-01

    The results of portable radio-station "Radiy-301" electromagnetic fields (EMF) emission measurement and specific absorption rate data evaluation has shown that workers' exposure EMF levels may elevate hygienic norms and hereupon can be health risk factor. Possible way of portable radio-station EMF dosimetry enhancement by means of domestic and international approaches harmonization is considered.

  4. Health Effects of Electromagnetic Fields: A Review of Literature.

    ERIC Educational Resources Information Center

    White, George L.; And Others

    1995-01-01

    Current evidence suggests that the effects of electromagnetic fields (EMF) disturb cell homeostasis at very low intensities by influencing discrete intracellular magnetic fields. The article reviews current research about the health effects of EMF, examining historical implications, childhood studies, adult studies, and popular press reports, and…

  5. Health Effects of Electromagnetic Fields: A Review of Literature.

    ERIC Educational Resources Information Center

    White, George L.; And Others

    1995-01-01

    Current evidence suggests that the effects of electromagnetic fields (EMF) disturb cell homeostasis at very low intensities by influencing discrete intracellular magnetic fields. The article reviews current research about the health effects of EMF, examining historical implications, childhood studies, adult studies, and popular press reports, and…

  6. External Field QED on Cauchy Surfaces for Varying Electromagnetic Fields

    NASA Astrophysics Data System (ADS)

    Deckert, D.-A.; Merkl, F.

    2016-08-01

    The Shale-Stinespring Theorem (J Math Mech 14:315-322, 1965) together with Ruijsenaar's criterion (J Math Phys 18(4):720-737, 1977) provide a necessary and sufficient condition for the implementability of the evolution of external field quantum electrodynamics between constant-time hyperplanes on standard Fock space. The assertion states that an implementation is possible if and only if the spatial components of the external electromagnetic four-vector potential {A_μ} are zero. We generalize this result to smooth, space-like Cauchy surfaces and, for general {A_μ}, show how the second-quantized Dirac evolution can always be implemented as a map between varying Fock spaces. Furthermore, we give equivalence classes of polarizations, including an explicit representative, that give rise to those admissible Fock spaces. We prove that the polarization classes only depend on the tangential components of {A_μ} w.r.t. the particular Cauchy surface, and show that they behave naturally under Lorentz and gauge transformations.

  7. Enhancing photocurrent transient spectroscopy by electromagnetic modeling.

    PubMed

    Diesinger, H; Panahandeh-Fard, M; Wang, Z; Baillargeat, D; Soci, C

    2012-05-01

    The shape and duration of photocurrent transients generated by a photoconductive switch depend on both the intrinsic response of the active material and the geometry of the transmission line structure. The present electromagnetic model decouples both shape forming contributions. In contrast to previously published work, it accounts for the particular operating mode of transient spectroscopy. The objective is to increase the time resolution by two approaches, by optimizing structural response and by deconvolving it from experimental data. The switch structure is represented by an effective transimpedance onto which the active material acts as current generator. As proof of concept, the response of a standard microstrip switch is modeled and deconvolved from experimental data acquired in GaAs, yielding a single exponential material response and hence supporting the validity of the approach. Beyond compensating for the response deterioration by the structure, switch architectures can be a priori optimized with respect to frequency response. As an example, it is shown that a microstrip gap that can be deposited on materials incompatible with standard lithography reduces pulse broadening by an order of magnitude if it is provided with transitions to coplanar access lines.

  8. Biological effects of electromagnetic fields and recently updated safety guidelines for strong static magnetic fields.

    PubMed

    Yamaguchi-Sekino, Sachiko; Sekino, Masaki; Ueno, Shoogo

    2011-01-01

    Humans are exposed daily to artificial and naturally occurring magnetic fields that originate from many different sources. We review recent studies that examine the biological effects of and medical applications involving electromagnetic fields, review the properties of static and pulsed electromagnetic fields that affect biological systems, describe the use of a pulsed electromagnetic field in combination with an anticancer agent as an example of a medical application that incorporates an electromagnetic field, and discuss the recently updated safety guidelines for static electromagnetic fields. The most notable modifications to the 2009 International Commission on Non-Ionizing Radiation Protection guidelines are the increased exposure limits, especially for those who work with or near electromagnetic fields (occupational exposure limits). The recommended increases in exposure were determined using recent scientific evidence obtained from animal and human studies. Several studies since the 1994 publication of the guidelines have examined the effects on humans after exposure to high static electromagnetic fields (up to 9.4 tesla), but additional research is needed to ascertain further the safety of strong electromagnetic fields.

  9. The effect of pulsed electromagnetic field therapy on food sensitivity.

    PubMed

    Monro, Jean A; Puri, Basant K

    2015-01-01

    Owing to the involvement of the immune system in the etiology of food sensitivity, and because pulsed electromagnetic field therapy is associated with beneficial immunologic changes, it was hypothesized that pulsed electromagnetic fields may have a beneficial effect on food sensitivity. A small pilot study was carried out in patients suffering from food sensitivity, with the antigen leukocyte antibody test being employed to index the degree of food sensitivity in terms of the number of foods to which each patient reacted. It was found that a 1-week course of pulsed electromagnetic field therapy, consisting of one hour's treatment per day, resulted in a reduction in the mean number of reactive foods of 10.75 (p < 0.05). On the basis of these results, a larger study is warranted.

  10. Quantum processes in short and intensive electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Titov, A. I.; Kämpfer, Burkhard; Hosaka, Atsushi; Takabe, Hideaki

    2016-05-01

    This work provides an overview of our recent results in studying two most important and widely discussed quantum processes: electron-positron pairs production off a probe photon propagating through a polarized short-pulsed electromagnetic (e.g. laser) wave field or generalized Breit-Wheeler process, and a single a photon emission off an electron interacting with the laser pules, so-called non-linear Compton scattering. We show that the probabilities of particle production in both processes are determined by interplay of two dynamical effects, where the first one is related to the shape and duration of the pulse and the second one is non-linear dynamics of the interaction of charged fermions with a strong electromagnetic field. We elaborate suitable expressions for the production probabilities and cross sections, convenient for studying evolution of the plasma in presence of strong electromagnetic fields.

  11. Electromagnetic Propulsion System for Spacecraft using Geomagnetic fields and Superconductors

    NASA Astrophysics Data System (ADS)

    Dadhich, Anang

    This thesis concentrates on developing an innovative method to generate thrust force for spacecraft in localized geomagnetic fields by various electromagnetic systems. The proposed electromagnetic propulsion system is an electromagnet, like normal or superconducting solenoid, having its own magnetic field which interacts with the planet's magnetic field to produce a reaction thrust force. The practicality of the system is checked by performing simulations in order the find the varying radius, velocity, and acceleration changes. The advantages, challenges, various optimization techniques, and viability of such a propulsion system in present day and future are discussed. The propulsion system such developed is comparable to modern MPD Thrusters and electric engines, and has various applications like spacecraft propulsion, orbit transfer and stationkeeping.

  12. The electromagnetic bio-field: clinical experiments and interferences

    PubMed Central

    Burnei, G; Hodorogea, D; Georgescu, I; Gavriliu, Ş; Drăghici, I; Dan, D; Vlad, C; Drăghici, L

    2012-01-01

    Introduction: One of the most important factors is the technical and scientifically rapid development that is continually modifying the world we live in and polluting it with electromagnetic radiations. A functional and structural influence of magnetic and electromagnetic field on living organisms is presented in the literature by many performed experiments. Material and methods: The notion of bio-field represents the electromagnetic field generated by the bio-structures, not only in their normal physiological activities but also in their pathological states. There is a tight interdependency between the bio-field and the bio-structure, which respects the primary notion of an electromagnetic field given by the Maxwell-Faraday laws, in which, the electromagnetic phenomena are simplified to the field variations. These variations can be expressed in a coherent differential equation system that bounds the field vectors to different space points at different time moments. Results: The living organisms cannot contain electrostatic and magneto-static fields due to the intense activity of the bio-structures. The biochemical reactions that have high rhythms and speeds always impose the electrodynamics character of the biologic field that also corresponds to the stability of the protein molecule that can be explained only through a dynamic way. The existent energy is not considered an exciting agent, and it does not lead to any effects. Conclusions: The parameters of these elementary bio-fields cannot yet be fully known due to technical reasons. The biological structures are very complex ones and undergo continuous dynamical activity. That is why the calculus model should be related to the constant dynamics, nowadays being very difficult to express. PMID:22802878

  13. The electromagnetic bio-field: clinical experiments and interferences.

    PubMed

    Burnei, G; Hodorogea, D; Georgescu, I; Gavriliu, Ş; Drăghici, I; Dan, D; Vlad, C; Drăghici, L

    2012-06-12

    One of the most important factors is the technical and scientifically rapid development that is continually modifying the world we live in and polluting it with electromagnetic radiations. A functional and structural influence of magnetic and electromagnetic field on living organisms is presented in the literature by many performed experiments. The notion of bio-field represents the electromagnetic field generated by the bio-structures, not only in their normal physiological activities but also in their pathological states. There is a tight interdependency between the bio-field and the bio-structure, which respects the primary notion of an electromagnetic field given by the Maxwell-Faraday laws, in which, the electromagnetic phenomena are simplified to the field variations. These variations can be expressed in a coherent differential equation system that bounds the field vectors to different space points at different time moments. The living organisms cannot contain electrostatic and magneto-static fields due to the intense activity of the bio-structures. The biochemical reactions that have high rhythms and speeds always impose the electrodynamics character of the biologic field that also corresponds to the stability of the protein molecule that can be explained only through a dynamic way. The existent energy is not considered an exciting agent, and it does not lead to any effects. The parameters of these elementary bio-fields cannot yet be fully known due to technical reasons. The biological structures are very complex ones and undergo continuous dynamical activity. That is why the calculus model should be related to the constant dynamics, nowadays being very difficult to express.

  14. On electromagnetic fields and their applications in the early universe

    NASA Astrophysics Data System (ADS)

    Ahonen, Jarkko Tapani

    1998-07-01

    The field equations of the electromagnetic field, combined with models of the early universe, make it possible to study electromagnetic phenomena at the early stages of the universe. Electromagnetic fields provide us with a tool to estimate electrical conductivity and transport coefficients (heat conductivity and viscosity) in the primordial plasma of the hot early universe. Electrical conductivity plays an important role, for example, in the dissipation of the axion field (a weakly interacting dark matter candidate) and in the creation and dissipation of the primordial magnetic field. On the other hand, heat conductivity and shear viscosity are important, for example, in connection with primordial density perturbations, i.e., galaxy formation, early phase transitions, and primordial magnetic fields. First, in paper I, we derived the equations of motion for the axion field coupled with an electromagnetic field. It was found that energy from the axion field can be transferred to the electromagnetic field. Therefore the damping of the axion field depends on electrical conductivity but that the electromagnetic dissipation cannot, however, significantly damp the axion field. In paper II we developed the tools with which to estimate electrical conductivity in the primordial plasma. We used the Boltzmann collision equation to study how a beam of charged particles will be scattered in the early hot universe. We integrated the collision integral numerically by a simple Monte Carlo integration routine. We discovered that the charged leptons give the largest contribution to the electrical conductivity; the quark contribution was found to be negligible. In Paper III, we estimated with an Abelian Higgs model what kind of a primordial magnetic field can be created in first order phase transition bubble collisions. Assuming that the Abelian model reflects the properties of the full electroweak case, we found that the seed field created is of the right order of magnitude in order

  15. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    SciTech Connect

    Timofeev, I. V.; Annenkov, V. V.; Arzhannikov, A. V.

    2015-11-15

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.

  16. Regimes of enhanced electromagnetic emission in beam-plasma interactions

    NASA Astrophysics Data System (ADS)

    Timofeev, I. V.; Annenkov, V. V.; Arzhannikov, A. V.

    2015-11-01

    The ways to improve the efficiency of electromagnetic waves generation in laboratory experiments with high-current relativistic electron beams injected into a magnetized plasma are discussed. It is known that such a beam can lose, in a plasma, a significant part of its energy by exciting a high level of turbulence and heating plasma electrons. Beam-excited plasma oscillations may simultaneously participate in nonlinear processes resulting in a fundamental and second harmonic emissions. It is obvious, however, that in the developed plasma turbulence the role of these emissions in the total energy balance is always negligible. In this paper, we investigate whether electromagnetic radiation generated in the beam-plasma system can be sufficiently enhanced by the direct linear conversion of resonant beam-driven modes into electromagnetic ones on preformed regular inhomogeneities of plasma density. Due to the high power of relativistic electron beams, the mechanism discussed may become the basis for the generator of powerful sub-terahertz radiation.

  17. Kinetic theory of plasma equilibrium in an electromagnetic field

    NASA Astrophysics Data System (ADS)

    Gorbunov, L. M.; Gradov, O. M.; Ziunder, D.; Ramazashvili, R. R.

    1981-04-01

    The present study examines the equilibrium of a direct-current-carrying plasma in an electromagnetic field under the assumption that the particles escaping from the plasma have a Maxwellian distribution. It is shown that an equilibrium state is possible only in the case of a definite relationship between the amplitude of the incident wave and the concentration of escaping particles. Attention is given to spatial variations of the electromagnetic field, and of the plasma density and flow velocity. The application of these effects in microwave devices is discussed.

  18. Near-field thermal electromagnetic transport: An overview

    NASA Astrophysics Data System (ADS)

    Edalatpour, Sheila; DeSutter, John; Francoeur, Mathieu

    2016-07-01

    A general near-field thermal electromagnetic transport formalism that is independent of the size, shape and number of heat sources is derived. The formalism is based on fluctuational electrodynamics, where fluctuating currents due to thermal agitation are added to Maxwell's curl equations, and is thus valid for heat sources in local thermodynamic equilibrium. Using a volume integral formulation, it is shown that the proposed formalism is a generalization of the classical electromagnetic scattering framework in which thermal emission is implicitly assumed to be negligible. The near-field thermal electromagnetic transport formalism is afterwards applied to a problem involving three spheres with size comparable to the wavelength, where all multipolar interactions are taken into account. Using the thermal discrete dipole approximation, it is shown that depending on the dielectric function, the presence of a third sphere slightly affects the spatial distribution of power absorbed compared to the two-sphere case. A transient analysis shows that despite a non-uniform spatial distribution of power absorbed, the sphere temperature remains spatially uniform at any instant due to the fact that the thermal resistance by conduction is much smaller than the resistance by radiation. The formalism proposed in this paper is general, and could be used as a starting point for adapting solution methods employed in traditional electromagnetic scattering problems to near-field thermal electromagnetic transport.

  19. Fluorescence Enhancement Under Controlled Electromagnetic Nanoenvironments

    DTIC Science & Technology

    2003-08-31

    Halas, "Fluorinated Nanodiamond as a wet chemistry precursor for diamond coatings covalently bonded to glass surface", Journal of the American Chemical...affinity for the surface of a metallic nanoshell. We have utilized this effect to determine the number of polyethylene glycol (PEG) molecules that can be... metal side of the nanoparticle. This is the only known nanostructure where large enhancements can be engineered in an "open" geometry, in other words

  20. Optimal control of electromagnetic field using metallic nanoclusters

    NASA Astrophysics Data System (ADS)

    Grigorenko, Ilya; Haas, Stephan; Balatsky, Alexander; Levi, A. F. J.

    2008-04-01

    The dielectric properties of metallic nanoclusters in the presence of an applied electromagnetic field are investigated using the non-local linear response theory. In the quantum limit we find a nontrivial dependence of the induced field and charge distributions on the spatial separation between the clusters and on the frequency of the driving field. Using a genetic algorithm, these quantum functionalities are exploited to custom-design sub-wavelength lenses with a frequency-controlled switching capability.

  1. Method for imaging with low frequency electromagnetic fields

    DOEpatents

    Lee, Ki H.; Xie, Gan Q.

    1994-01-01

    A method for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The traveltimes corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter .alpha. for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography.

  2. Method for imaging with low frequency electromagnetic fields

    DOEpatents

    Lee, K.H.; Xie, G.Q.

    1994-12-13

    A method is described for imaging with low frequency electromagnetic fields, and for interpreting the electromagnetic data using ray tomography, in order to determine the earth conductivity with high accuracy and resolution. The imaging method includes the steps of placing one or more transmitters, at various positions in a plurality of transmitter holes, and placing a plurality of receivers in a plurality of receiver holes. The transmitters generate electromagnetic signals which diffuse through a medium, such as earth, toward the receivers. The measured diffusion field data H is then transformed into wavefield data U. The travel times corresponding to the wavefield data U, are then obtained, by charting the wavefield data U, using a different regularization parameter [alpha] for each transform. The desired property of the medium, such as conductivity, is then derived from the velocity, which in turn is constructed from the wavefield data U using ray tomography. 13 figures.

  3. Oxidative and genotoxic effects of 900 MHz electromagnetic fields in the earthworm Eisenia fetida.

    PubMed

    Tkalec, Mirta; Stambuk, Anamaria; Srut, Maja; Malarić, Krešimir; Klobučar, Göran I V

    2013-04-01

    Accumulating evidence suggests that exposure to radiofrequency electromagnetic field (RF-EMF) can have various biological effects. In this study the oxidative and genotoxic effects were investigated in earthworms Eisenia fetida exposed in vivo to RF-EMF at the mobile phone frequency (900 MHz). Earthworms were exposed to the homogeneous RF-EMF at field levels of 10, 23, 41 and 120 V m(-1) for a period of 2h using a Gigahertz Transversal Electromagnetic (GTEM) cell. At the field level of 23 V m(-1) the effect of longer exposure (4h) and field modulation (80% AM 1 kHz sinusoidal) was investigated as well. All exposure treatments induced significant genotoxic effect in earthworms coelomocytes detected by the Comet assay, demonstrating DNA damaging capacity of 900 MHz electromagnetic radiation. Field modulation additionally increased the genotoxic effect. Moreover, our results indicated the induction of antioxidant stress response in terms of enhanced catalase and glutathione reductase activity as a result of the RF-EMF exposure, and demonstrated the generation of lipid and protein oxidative damage. Antioxidant responses and the potential of RF-EMF to induce damage to lipids, proteins and DNA differed depending on the field level applied, modulation of the field and duration of E. fetida exposure to 900 MHz electromagnetic radiation. Nature of detected DNA lesions and oxidative stress as the mechanism of action for the induction of DNA damage are discussed.

  4. Deformation methods in modelling of the inner magnetospheric electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Toivanen, P. K.

    2007-12-01

    Various deformation methods have been widely used in animation image processing. In common terms, they are mathematical presentations of deformations of an image drawn on an elastic material under stretching or compression of the material. Such a method has also been used in modelling of the magnetospheric magnetic fields, and recently been generalized to include also the electric fields. In this presentations, the theory of the deformation method and an application in a form of a new global magnetospheric electromagnetic field model are previewed. The main focus of the presentation is on the inner magnetospheric current systems and associated electromagnetic fields during quiet and disturbed periods. Finally, a short look at the modern deformation methods in image processing is taken. These methods include the Free Form Deformations and Moving Least Squares Deformations, and their future applications in magnetospheric field modelling are discussed.

  5. Ionization of atoms in strong low-frequency electromagnetic field

    SciTech Connect

    Krainov, V. P.

    2010-08-15

    The ionization of atoms in a low-frequency linearly polarized electromagnetic field (the photon energy is much lower than the ionization potential of an atom) is considered under new conditions, in which the Coulomb interaction of an electron with the atomic core in the final state of the continuum cannot be considered in perturbation theory in the interaction of the electron with the electromagnetic field. The field is assumed to be much weaker that the atomic field. In these conditions, the classical motion of the electron in the final state of the continuum becomes chaotic (so-called dynamic chaos). Using the well-known Chirikov method of averaging over chaotic variations of the phase of motion, the problem can be reduced to non-linear diffusion on the energy scale. We calculate the classical electron energy in the final state, which is averaged over fast chaotic oscillations and takes into account both the Coulomb field and the electromagnetic field. This energy is used to calculate the probability of ionization from the ground state of the atom to a lower-lying state in the continuum using the Landau-Dykhne approximation (to exponential accuracy). This ionization probability noticeably depends on the field frequency. Upon a decrease in frequency, a transition to the well-known tunnel ionization limit with a probability independent of the field frequency is considered.

  6. Electromagnetic time reversal focusing of near field waves in metamaterials

    NASA Astrophysics Data System (ADS)

    Chabalko, Matthew J.; Sample, Alanson P.

    2016-12-01

    Precise control of electromagnetic energy on a deeply subwavelength scale in the near field regime is a fundamentally challenging problem. In this letter we demonstrate the selective focusing of electromagnetic energy via the electromagnetic time reversal in the near field of a metamaterial. Our analysis begins with fundamental mathematics, and then is extended to the experimental realm where focusing in space and time of the magnetic fields in the near field of a 1-Dimensional metamaterial is shown. Under time reversal focusing, peak instantaneous fields at receiver locations are at minimum ˜200% greater than other receivers. We then leverage the strong selective focusing capabilities of the system to show individual and selective powering of light emitting diodes connected to coil receivers placed in the near field of the metamaterial. Our results show the possibility of improving display technologies, near field imaging systems, increasing channel capacity of near field communication systems, and obtaining a greater control of energy delivery in wireless power transfer systems.

  7. Relativistic Particle in Electromagnetic Fields with a Generalized Uncertainty Principle

    NASA Astrophysics Data System (ADS)

    Merad, M.; Zeroual, F.; Falek, M.

    2012-05-01

    In this paper, we propose to solve the relativistic Klein-Gordon and Dirac equations subjected to the action of a uniform electromagnetic field with a generalized uncertainty principle in the momentum space. In both cases, the energy eigenvalues and their corresponding eigenfunctions are obtained. The limit case is then deduced for a small parameter of deformation.

  8. Transducer measures temperature differentials in presence of strong electromagnetic fields

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Measurement of temperature rise of cooling water under pressure and in strong electromagnetic fields is accomplished by a transducer using a magnetically shielded thermocouple arrangement. The thermocouple junctions are immersed in oil to isolate them from electric currents in the water.

  9. What Message Should Health Educators Give regarding Electromagnetic Fields?

    ERIC Educational Resources Information Center

    Al-Khamees, Nedaa A.

    2008-01-01

    The possibility of extremely low frequency electromagnetic fields (ELF EMF) causing a number of medical conditions and common symptoms remains a concern and presents somewhat of a quandary to health educators in view of conflicting results. This study investigated the relationship of a number of EMF sources to reported symptoms in an attempt to,…

  10. What Message Should Health Educators Give regarding Electromagnetic Fields?

    ERIC Educational Resources Information Center

    Al-Khamees, Nedaa A.

    2008-01-01

    The possibility of extremely low frequency electromagnetic fields (ELF EMF) causing a number of medical conditions and common symptoms remains a concern and presents somewhat of a quandary to health educators in view of conflicting results. This study investigated the relationship of a number of EMF sources to reported symptoms in an attempt to,…

  11. Electromagnetic Field in Lyra Manifold: A First Order Approach

    NASA Astrophysics Data System (ADS)

    Casana, R.; de Melo, C. A. M.; Pimentel, B. M.

    2005-12-01

    We discuss the coupling of the electromagnetic field with a curved and torsioned Lyra manifold using the Duffin-Kemmer-Petiau theory. We will show how to obtain the equations of motion and energy-momentum and spin density tensors by means of the Schwinger Variational Principle.

  12. Oscillator strength sum rules with an external electromagnetic field

    NASA Astrophysics Data System (ADS)

    Cabrera-Trujillo, R.; Sabin, John R.; Öhrn, Yngve; Oddershede, J.

    1998-04-01

    We demonstrate that the Bethe, and therefore the Thomas-Reiche-Kuhn, sum rule is unaffected by the presence of an applied external electromagnetic field in the exact case. We use the consequence that the first-order perturbation contribution must also vanish to derive a necessary condition for the completeness of computational one-electron basis sets.

  13. Does three-dimensional electromagnetic field inherit the spacetime symmetries?

    NASA Astrophysics Data System (ADS)

    Cvitan, M.; Dominis Prester, P.; Smolić, I.

    2016-04-01

    We prove that the electromagnetic field in a (1+2)-dimensional spacetime necessarily inherits the symmetries of the spacetime metric in a large class of generalized Einstein-Maxwell theories. The Lagrangians of the studied theories have general diff-covariant gravitational part and include both the gravitational and the gauge Chern-Simons terms.

  14. Effects of pulsed electromagnetic fields on benign prostate hyperplasia.

    PubMed

    Giannakopoulos, Xenophon K; Giotis, Christos; Karkabounas, Spyridon Ch; Verginadis, Ioannis I; Simos, Yannis V; Peschos, Dimitrios; Evangelou, Angelos M

    2011-12-01

    Benign prostate hyperplasia (BPH) has been treated with various types of electromagnetic radiation methods such as transurethral needle ablation (TUNA), interstitial laser therapy (ILC), holmium laser resection (HoLRP). In the present study, the effects of a noninvasive method based on the exposure of patients with BPH to a pulsative EM Field at radiofrequencies have been investigated. Twenty patients with BPH, aging 68-78 years old (y.o), were enrolled in the study. Patients were randomly divided into two groups: the treatment group (10 patients, 74.0 ± 5.7 y.o) treated with the α-blocker Alfusosin, 10 mg/24 h for at least 4 weeks, and the electromagnetic group (10 patients, 73.7 ± 6.3 y.o) exposed for 2 weeks in a very short wave duration, pulsed electromagnetic field at radiofrequencies generated by an ion magnetic inductor, for 30 min daily, 5 consecutive days per week. Patients of both groups were evaluated before and after drug and EMF treatment by values of total PSA and prostatic PSA fraction, acid phosphate, U/S estimation of prostate volume and urine residue, urodynamic estimation of urine flow rate, and International Prostate Symptom Score (IPSS). There was a statistically significant decrease before and after treatment of IPSS (P < 0.02), U/S prostate volume (P < 0.05), and urine residue (P < 0.05), as well as of mean urine flow rate (P < 0.05) in patients of the electromagnetic group, in contrast to the treatment group who had only improved IPSS (P < 0.05). There was also a significant improvement in clinical symptoms in patients of the electromagnetic group. Follow-up of the patients of this group for one year revealed that results obtained by EMFs treatment are still remaining. Pulsed electromagnetic field at radiofrequencies may benefit patients with benign prostate hyperplasia treated by a non-invasive method.

  15. Human osteoarthritic chondrocytes exposed to extremely low-frequency electromagnetic fields (ELF) and therapeutic application of musically modulated electromagnetic fields (TAMMEF) systems: a comparative study.

    PubMed

    Corallo, Claudio; Volpi, Nila; Franci, Daniela; Vannoni, Daniela; Leoncini, Roberto; Landi, Giacomo; Guarna, Massimo; Montella, Antonio; Albanese, Antonietta; Battisti, Emilio; Fioravanti, Antonella; Nuti, Ranuccio; Giordano, Nicola

    2013-06-01

    Osteoarthritis (OA) is the most common joint disease, characterized by matrix degradation and changes in chondrocyte morphology and metabolism. Literature reported that electromagnetic fields (EMFs) can produce benefits in OA patients, even if EMFs mechanism of action is debated. Human osteoarthritic chondrocytes isolated from femoral heads were cultured in vitro in bidimensional (2-D) flasks and in three-dimensional (3-D) alginate beads to mimic closely cartilage environment in vivo. Cells were exposed 30 min/day for 2 weeks to extremely low-frequency electromagnetic field (ELF) with fixed frequency (100 Hz) and to therapeutic application of musically modulated electromagnetic field (TAMMEF) with variable frequencies, intensities, and waveforms. Cell viability was measured at days 7 and 14, while healthy-cell density, heavily vacuolized (hv) cell density, and cluster density were measured by light microscopy only for 3-D cultures after treatments. Cell morphology was observed for 2-D and 3-D cultures by transmission electron microscopy (TEM). Chondrocyte exposure to TAMMEF enhances cell viability at days 7 and 14 compared to ELF. Light microscopy analysis showed that TAMMEF enhances healthy-cell density, reduces hv-cell density and clustering, compared to ELF. Furthermore, TEM analysis showed different morphology for 2-D (fibroblast-like) and 3-D (rounded shape) cultures, confirming light microscopy results. In conclusion, EMFs are effective and safe for OA chondrocytes. TAMMEF can positively interfere with OA chondrocytes representing an innovative non-pharmacological approach to treat OA.

  16. QED effective action in magnetic field backgrounds and electromagnetic duality

    NASA Astrophysics Data System (ADS)

    Kim, Sang Pyo

    2011-09-01

    In the in-out formalism we advance a method of the inverse scattering matrix for calculating effective actions in pure magnetic field backgrounds. The one-loop effective actions are found in a localized magnetic field of Sauter type and approximately in a general magnetic field by applying the uniform semiclassical approximation. The effective actions exhibit the electromagnetic duality between a constant electric field and a constant magnetic field and between E(x)=Esech2(x/L) and B(x)=Bsech2(x/L).

  17. Electromagnetic fields from mobile phone base station - variability analysis.

    PubMed

    Bienkowski, Pawel; Zubrzak, Bartlomiej

    2015-09-01

    The article describes the character of electromagnetic field (EMF) in mobile phone base station (BS) surroundings and its variability in time with an emphasis on the measurement difficulties related to its pulse and multi-frequency nature. Work also presents long-term monitoring measurements performed recently in different locations in Poland - small city with dispersed building development and in major polish city - dense urban area. Authors tried to determine the trends in changing of EMF spectrum analyzing daily changes of measured EMF levels in those locations. Research was performed using selective electromagnetic meters and also EMF meter with spectrum analysis.

  18. [Clinical monitoring in areas of exposure to radiofrequency electromagnetic fields].

    PubMed

    Suvorov, I M

    2013-01-01

    Clinical syndromes induced by high intensity radiofrequency electromagnetic field chronic exposure are described. Persons injured by occupational exposure have been observed central nervous system changes in diencephalic syndrome form, cardio-vascular system changes revealed in atherosclerosis, isch(a)emic heart disease and coronary insufficiency rapid progressive expansion. General public living in territory of radar station exposure zone different functional disorders have been identified: vegetative dystonia (asthenovegetative syndrome), thrombocytopenia, decrease of blood coagulation index, and thyroid gland function changes. Observed diseases clinical variability may be determined by electromagnetic exposure characteristics.

  19. Local field enhancement on metallic periodic surface structures produced by femtosecond laser pulses

    SciTech Connect

    Ionin, Andrei A; Kudryashov, Sergei I; Ligachev, A E; Makarov, Sergei V; Mel'nik, N N; Rudenko, A A; Seleznev, L V; Sinitsyn, D V; Khmelnitskii, R A

    2013-04-30

    Periodic surface structures on aluminium are produced by femtosecond laser pulses for efficient excitation of surface electromagnetic waves using a strong objective (NA = 0.5). The local electromagnetic field enhancement on the structures is measured using the technique of surface-enhanced Raman scattering from pyridine molecules. (extreme light fields and their applications)

  20. Effects of pulsed electromagnetic fields on postmenopausal osteoporosis.

    PubMed

    Zhu, Siyi; He, Hongchen; Zhang, Chi; Wang, Haiming; Gao, Chengfei; Yu, Xijie; He, Chengqi

    2017-09-01

    Postmenopausal osteoporosis (PMOP) is considered to be a well-defined subject that has caused high morbidity and mortality. In elderly women diagnosed with PMOP, low bone mass and fragile bone strength have been proven to significantly increase risk of fragility fractures. Currently, various anabolic and anti-resorptive therapies have been employed in an attempt to retain healthy bone mass and strength. Pulsed electromagnetic fields (PEMFs), first applied in treating patients with delayed fracture healing and nonunions, may turn out to be another potential and effective therapy for PMOP. PEMFs can enhance osteoblastogenesis and inhibit osteoclastogenesis, thus contributing to an increase in bone mass and strength. However, accurate mechanisms of the positive effects of PEMFs on PMOP remain to be further elucidated. This review attempts to summarize recent advances of PEMFs in treating PMOP based on clinical trials, and animal and cellular studies. Possible mechanisms are also introduced, and the future possibility of application of PEMFs on PMOP are further explored and discussed. Bioelectromagnetics. 38:406-424, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  1. Numerical Analysis of Electromagnetic Fields in Multiscale Model

    NASA Astrophysics Data System (ADS)

    Ma, Ji; Fang, Guang-You; Ji, Yi-Cai

    2015-04-01

    Modeling technique for electromagnetic fields excited by antennas is an important topic in computational electromagnetics, which is concerned with the numerical solution of Maxwell's equations. In this paper, a novel hybrid technique that combines method of moments (MoM) with finite-difference time-domain (FDTD) method is presented to handle the problem. This approach employed Huygen's principle to realize the hybridization of the two classical numerical algorithms. For wideband electromagnetic data, the interpolation scheme is used in the MoM based on the dyadic Green's function. On the other hand, with the help of equivalence principle, the scattered electric and magnetic fields on the Huygen's surface calculated by MoM are taken as the sources for FDTD. Therefore, the electromagnetic fields in the environment can be obtained by employing finite-difference time-domain method. Finally, numerical results show the validity of the proposed technique by analyzing two canonical samples. Supported in part by China Postdoctoral Science Foundation under Grant No. 201M550839, and in part by the Key Research Program of the Chinese Academy of Sciences under Grant No. KGZD-EW-603

  2. Electromagnetic Field Effects in Semiconductor Crystal Growth

    NASA Technical Reports Server (NTRS)

    Dulikravich, George S.

    1996-01-01

    This proposed two-year research project was to involve development of an analytical model, a numerical algorithm for its integration, and a software for the analysis of a solidification process under the influence of electric and magnetic fields in microgravity. Due to the complexity of the analytical model that was developed and its boundary conditions, only a preliminary version of the numerical algorithm was developed while the development of the software package was not completed.

  3. The electromagnetic force field, fluid flow field and temperature profiles in levitated metal droplets

    NASA Technical Reports Server (NTRS)

    El-Kaddah, N.; Szekely, J.

    1982-01-01

    A mathematical representation was developed for the electromagnetic force field, the flow field, the temperature field (and for transport controlled kinetics), in a levitation melted metal droplet. The technique of mutual inductances was employed for the calculation of the electromagnetic force field, while the turbulent Navier - Stokes equations and the turbulent convective transport equations were used to represent the fluid flow field, the temperature field and the concentration field. The governing differential equations, written in spherical coordinates, were solved numerically. The computed results were in good agreement with measurements, regarding the lifting force, and the average temperature of the specimen and carburization rates, which were transport controlled.

  4. Proton Radiography as an electromagnetic field and density perturbation diagnostic

    SciTech Connect

    Mackinnon, A; Patel, P; Town, R; Edwards, M; Phillips, T; Lerner, S; Price, D; Hicks, D; Key, M; Hatchett, S; Wilks, S; King, J; Snavely, R; Freeman, R; Boehlly, T; Koenig, M; Martinolli, E; Lepape, S; Benuzzi-Mounaix, A; Audebert, P; Gauthier, J; Borghesi, M; Romagnani, L; Toncian, T; Pretzler, G; Willi, O

    2004-04-15

    Laser driven proton beams have been used to diagnose transient fields and density perturbations in laser produced plasmas. Grid deflectometry techniques have been applied to proton radiography to obtain precise measurements of proton beam angles caused by electromagnetic fields in laser produced plasmas. Application of proton radiography to laser driven implosions has demonstrated that density conditions in compressed media can be diagnosed with MeV protons. This data has shown that proton radiography can provide unique insight into transient electromagnetic fields in super critical density plasmas and provide a density perturbation diagnostics in compressed matter . PACS numbers: 52.50.Jm, 52.40.Nk, 52.40.Mj, 52.70.Kz

  5. Momentum of the electromagnetic field in transparent dielectric media

    NASA Astrophysics Data System (ADS)

    Mansuripur, Masud

    2007-09-01

    We present arguments in favor of the proposition that the momentum of light inside a transparent dielectric medium is the arithmetic average of the Minkowski and Abraham momenta. Using the Lorentz transformation of the fields (and of the coordinates) from a stationary to a moving reference frame, we show the consistent transformation of electromagnetic energy and momentum between the two frames. We also examine the momentum of static (i.e., time-independent) electromagnetic fields, and show that the close connection that exists between the Poynting vector and the momentum density extends all the way across the frequency spectrum to this zero-frequency limit. In the specific example presented in this paper, the static field inside a non-absorbing dielectric material turns out to have the Minkowski momentum.

  6. Controlling Electromagnetic Field by Graded Meta-materials

    NASA Astrophysics Data System (ADS)

    Sun, Lei

    Metamaterials , i.e. artificial materials with electromagnetic properties not readily available in nature, have become a major research topic in both scientific and engineering communities. Being different from conventional materials, metamaterials possess peculiar electromagnetic properties, e.g. negative refractive index, depending on their structures. In particular, metamaterials form a basis for achieving cloaking device that makes an object invisible or transparency to the probing electromagnetic wave. This topic has significant impact on various fields ranging from optics, medicine, biology to nanotechnology. Several cloaking techniques have been proposed by different research groups, namely, anomalous localized resonance, transformation optics, and scattering cancellation, etc. Each of them has its own advantages and disadvantages. For instance, the limitation in working frequency is a primary disadvantage of them. This thesis is concentrated on controlling electromagnetic field by graded metamaterials, i.e, metamaterials with graded structures, with the objective to realize the broadband electromagnetic transparency by extending the working frequency. Regarding the limitations of existing cloaking techniques, we propose the graded model based on the scattering cancellation technique, because it does not rely on resonant phenomena, and is fairly robust to relatively high variations of the shape and electromagnetic properties of the cloaked object. We modify the original Mie theory and Rayleigh scattering theory to deal with the graded metamaterial structures, and calculate the scattering cross section of graded isotropic and anisotropic spherical structures, an alytically and numerically. For the graded isotropic spherical structure, we achieve the exact analytic expressions for both full-wave and Rayleigh scattering cross sections, within our modified Mie theory and Rayleigh scattering theory. The numerical studies on the scattering cross sections clearly

  7. Consequences of Coupled Electromagnetic-Gravitational Fields

    NASA Technical Reports Server (NTRS)

    Smalley, Larry

    2002-01-01

    In the late 1980s there was a flurry of activities involving the newly discovered high Tc superconductors in the development of new devices such as more efficient current transmission, transformers, generators, and motors. One such developmental project by Podkletnov in 1992 noted some small, anomalous gravitational behaviors. A following unpublished paper by Podkletnov 1995 provided data with larger effects using a larger (approx. 25 cm) superconducting disk. Unfortunately this disk was extremely fragile and was broken beyond repair. To date, these experiments have not been successfully repeated because of the difficulties of producing stable, durable (and fired) superconducting disks. This problem with firing these disks has been solved by Li. What remains is to install the disk in "motor", at superconducting temperatures in the presence of appropriately tailored magnetic fields.

  8. Designing localized electromagnetic fields in a source-free space.

    PubMed

    Borzdov, George N

    2002-06-01

    An approach to characterizing and designing localized electromagnetic fields, based on the use of differentiable manifolds, differentiable mappings, and the group of rotation, is presented. By way of illustration, novel families of exact time-harmonic solutions to Maxwell's equations in the source-free space--localized fields defined by the rotation group--are obtained. The proposed approach provides a broad spectrum of tools to design localized fields, i.e., to build-in symmetry properties of oscillating electric and magnetic fields, to govern the distributions of their energy densities (both size and form of localization domains), and to set the structure of time-average energy fluxes. It is shown that localized fields can be combined as constructive elements to obtain a complex field structure with desirable properties, such as one-, two-, or three-dimensional field gratings. The proposed approach can be used in designing localized electromagnetic fields to govern motion and state of charged and neutral particles. As an example, motion of relativistic electrons in one-dimensional and three-dimensional field gratings is treated.

  9. Radiotelephone with reduced electromagnetic field in human head

    NASA Astrophysics Data System (ADS)

    King, Ronold W. P.

    1995-01-01

    The quarter-wave monopole base driven over a circular ground plane with a finite radius has applications in over-the-horizon radar and on surveillance aircraft. A new use, for which the analysis is given in this paper, is as an over-the-head-mounted antenna for cellular telephones. With this design, the electromagnetic field in the head and the associated specific absorption rate of electromagnetic energy are greatly reduced when compared with the conventional hand-held transceiver. A complete analysis is carried out of the electromagnetic field on the surface of the head and throughout its interior when the head is modeled as a cylinder with the electrical properties of the brain enclosed in a wall with the thickness and electrical properties of the skull. Graphs and tables are provided that give the field in the air on the surface of the head and in the skull and brain. The far field is also determined. The results are compared with those obtained with the hand-held radiotelephone (King, 1995).

  10. Enhanced Direction of Arrival Estimation through Electromagnetic Modeling

    NASA Astrophysics Data System (ADS)

    Cordill, Brian

    Engineering is a high art that balances modeling the physical world and designing meaningful solutions based on those models. Array signal processing is no exception, and many innovative and creative solutions have come from the field of array processing. However, many of the innovative algorithms that permeate the field are based on a very simple signal model of an array. This simple, although powerful, model is at times a pale reflection of the complexities inherent in the physical world, and this model mismatch opens the door to the performance degradation of any solution for which the model underpins. This dissertation seeks to explore the impact of model mismatch upon common array processing algorithms. To that end, this dissertation brings together the disparate topics of electromagnetics and signal processing. Electromagnetics brings a singular focus on the physical interactions of electromagnetic waves and physical array structures, while signal processing brings modern computational power to solve difficult problems. We delve into model mismatch in two ways; first, by developing a blind array calibration routine that estimates model mismatch and incorporates that knowledge into the reiterative superresoluiton (RISR) direction of arrival estimation algorithm; second, by examining model mismatch between a transmitting and receiving array, and assessing the impact of this mismatch on prolific direction of arrival estimation algorithms. In both of these studies we show that engineers have traded algorithm performance for model simplicity, and that if we are willing to deal with the added complexity we can recapture that lost performance.

  11. Electromagnetic fields in the exterior of an oscillating relativistic star - II. Electromagnetic damping

    NASA Astrophysics Data System (ADS)

    Rezzolla, Luciano; Ahmedov, Bobomurat J.

    2016-07-01

    An important issue in the asteroseismology of compact and magnetized stars is the determination of the dissipation mechanism which is most efficient in damping the oscillations when these are produced. In a linear regime and for low-multipolarity modes, these mechanisms are confined to either gravitational-wave or electromagnetic losses. We here consider the latter and compute the energy losses in the form of Poynting fluxes, Joule heating and Ohmic dissipation in a relativistic oscillating spherical star with a dipolar magnetic field in vacuum. While this approach is not particularly realistic for rapidly rotating stars, it has the advantage that it is fully analytic and that it provides expressions for the electric and magnetic fields produced by the most common modes of oscillation both in the vicinity of the star and far away from it. In this way, we revisit and extend to a relativistic context the classical estimates of McDermott et al. Overall, we find that general-relativistic corrections lead to electromagnetic damping time-scales that are at least one order of magnitude smaller than in Newtonian gravity. Furthermore, with the only exception of g (gravity) modes, we find that f (fundamental), p (pressure), i (interface) and s (shear) modes are suppressed more efficiently by gravitational losses than by electromagnetic ones.

  12. [New mechanisms of biological effects of electromagnetic fields].

    PubMed

    Buchachenko, A L; Kuznetsov, D A; Berdinskiĭ, V L

    2006-01-01

    The production of ATP in mitochondria depends on the magnesium nuclear spin and magnetic moment of a Mg2+ ion in creatine kinase and ATPase. This suggests that enzymatic synthesis of ATP is an ion-radical process and thus depends on the external magnetic field (magnetobiology originates from this fact) and microwave fields, which control the spin states of ion-radical pairs and affect the ATP synthesis. The chemical mechanism of ATP synthesis and the origin of biological effects of electromagnetic (microwave) fields are discussed.

  13. Invariant superoscillatory electromagnetic fields in 3D-space

    NASA Astrophysics Data System (ADS)

    Makris, K. G.; Papazoglou, D. G.; Tzortzakis, S.

    2017-01-01

    We derive exact solutions of Maxwell’s equations based on superoscillatory superpositions of vectorial Bessel beams. These novel beams are diffraction-free and can support subwavelength features in their transverse electromagnetic fields, without the presence of any evanescent waves. These features can be propagated into the far field. Approximate solutions in closed form are also derived based on asymptotic expansions of Bessel functions for simple prescribed subwavelength patterns. The superoscillatory characteristics of both electric, magnetic field components (transverse and longitudinal), and the Poynting vector, as well as, the effect of nonparaxiality are systematically investigated.

  14. Effects of noise and electromagnetic fields on reproductive outcomes.

    PubMed Central

    Meyer, R E; Aldrich, T E; Easterly, C E

    1989-01-01

    Much public health research has been directed to studies of cancer risks due to chemical agents. Recently, increasing attention has been given to adverse reproductive outcomes as another, shorter-term biologic indicator of public health impact. Further, several low-level ubiquitous physical agents have been implicated recently as possibly affecting human health. These physical factors (noise and electromagnetic fields) represent difficult topics for research with epidemiologic study methods. This paper provides a brief review of the published data related to the risk of adverse reproductive outcomes and exposure to noise or electromagnetic fields. The discussion includes ideas for possible biologic mechanisms, considerations for exposure assessment, and suggestions for epidemiologic research. PMID:2667980

  15. Soft hairs on isolated horizon implanted by electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Mao, Pujian; Wu, Xiaoning; Zhang, Hongbao

    2017-03-01

    Inspired by the recent proposal of soft hair on black holes in Hawking et al (2016 Phys. Rev. Lett. 116 231301), we have shown that an isolated horizon carries soft hairs implanted by electromagnetic fields. The solution space and the asymptotic symmetries of Einstein–Maxwell theory have been worked out explicitly near the isolated horizon. The conserved current has been computed and an infinite number of near horizon charges have been introduced from the electromagnetic fields associated with the asymptotic U(1) symmetry near the horizon, which indicates the fact that the isolated horizon carries a large amount of soft electric hairs. The soft electric hairs, i.e. asymptotic U(1) charges, are shown to be equivalent to the electric multipole moments of isolated horizons. It is further argued that the isolated horizon supertranslation is from the ambiguity of its foliation and an analogue of memory effect on horizon can be expected.

  16. Acoustic effect of an electromagnetic pulsed UHF field

    SciTech Connect

    Kapyrin, Yu.V.; Moiseev, V.I.; Petrenko, V.V.

    1988-06-01

    During the course of studies on the Fakel linear accelerator it was found that the metal structures of the electrodynamic components of the accelerator are subjected to ultrasonic vibrations, the intensity and spectral composition of which depend on the operating regimes of its high-frequency system and on the conditions of resonance energy exchange between the electromagnetic field and the particle beam. From the results of calculations and measurements, the authors of this paper propose, without ruling out the contribution of other sources, that the ultrasonic signals observed in the irises and regular square waveguides of an accelerator can be attributed to the A ponderomotive effect of powerful pulses of the high-frequency electromagnetic field.

  17. Asseleration of ions in turbulent electromagnetic field during dipolarization events

    NASA Astrophysics Data System (ADS)

    Zhukova, Elena; Popov, Victor

    2017-04-01

    In spite of the long time interest for the acceleration of hight energetic ions in the Earth's magnetotail, considerable uncertainty remains as to the quantitative influence of different acceleration mechanism and their modifications. Both theoretical and numerical studies predict a hardening of the energy spectra of the particles wandering into the current sheet. Such energetic ion fluxes in the near-Earth tail were usually observed during magnetic dipolarizations or presence of turbulent electromagnetic field in the central region of current sheet that can effectively interact with the charged particles and energize them. The results demonstrate particle acceleration by separate two mechanisms and by their joint action. Both acceleration mechanisms lead to the formation of powered tails in proton distribution functions. Generally acceleration on magnetic dipolarization can be more effective in comparison with turbulent electromagnetic field.

  18. Growth characteristics of mung beans and water convolvuluses exposed to 425-MHz electromagnetic fields.

    PubMed

    Jinapang, Peeraya; Prakob, Panida; Wongwattananard, Pongtorn; Islam, Naz E; Kirawanich, Phumin

    2010-10-01

    Effects of high-frequency, continuous wave (CW) electromagnetic fields on mung beans (Vigna radiata L.) and water convolvuluses (Ipomoea aquatica Forssk.) were studied at different growth stages (pre-sown seed and early seedling). Specifically, the effects of the electromagnetic source's power and duration (defined as power-duration level) on the growth of the two species were studied. Mung beans and water convolvuluses were exposed to electromagnetic fields inside a specially designed chamber for optimum field absorption, and the responses of the seeds to a constant frequency at various power levels and durations of exposure were monitored. The frequency used in the experiments was 425 MHz, the field strengths were 1 mW, 100 mW, and 10 W, and the exposure durations were 1, 2, and 4 h. Results show that germination enhancement is optimum for the mung beans at 100 mW/1 h power-duration level, while for water convolvuluses the optimum germination power-duration level was 1 mW/2 h. When both seed types were exposed at the early sprouting phase with their respective optimum power-duration levels for optimum seed growth, water convolvuluses showed growth enhancement while mung bean sprouts showed no effects. Water content analysis of the seeds suggests thermal effects only at higher field strength.

  19. Immunorehabilitating effect of ultrahigh frequency electromagnetic fields in immunocompromised animals.

    PubMed

    Pershin, S B; Bobkova, A S; Derevnina, N A; Sidorov, V D

    2013-06-01

    We observed immunorehabilitation effects of ultrahigh frequency electromagnetic fields (microwaves) in immunocompromised animals. It was shown that microwave irradiation of the thyroid gland area could abolish actinomycin D- and colchicine-induced immunosuppression and did not affect immunosuppression caused by 5-fluorouracil. These findings suggest that changes in the hormonal profile of the organism during microwave exposure can stimulate the processes of transcription and mitotic activity of lymphoid cells.

  20. Immune Response to Electromagnetic Fields through Cybernetic Modeling

    SciTech Connect

    Godina-Nava, J. J.; Segura, M. A. Rodriguez; Cadena, S. Reyes; Sierra, L. C. Gaitan

    2008-08-11

    We study the optimality of the humoral immune response through a mathematical model, which involves the effect of electromagnetic fields over the large lymphocytes proliferation. Are used the so called cybernetic variables in the context of the matching law of microeconomics or mathematical psychology, to measure the large lymphocytes population and to maximize the instantaneous antibody production rate in time during the immunologic response in order to most efficiently inactivate the antigen.

  1. Immune Response to Electromagnetic Fields through Cybernetic Modeling

    NASA Astrophysics Data System (ADS)

    Godina-Nava, J. J.; Segura, M. A. Rodríguez; Cadena, S. Reyes; Sierra, L. C. Gaitán

    2008-08-01

    We study the optimality of the humoral immune response through a mathematical model, which involves the effect of electromagnetic fields over the large lymphocytes proliferation. Are used the so called cybernetic variables in the context of the matching law of microeconomics or mathematical psychology, to measure the large lymphocytes population and to maximize the instantaneous antibody production rate in time during the immunologic response in order to most efficiently inactivate the antigen.

  2. Low-frequency electromagnetic field in a Wigner crystal

    SciTech Connect

    Stupka, Anton

    2013-03-15

    Long-wave low-frequency oscillations are described in a Wigner crystal by generalization of the reverse continuum model for the case of electronic lattice. The internal self-consistent long-wave electromagnetic field is used to describe the collective motions in the system. The eigenvectors and eigenvalues of the obtained system of equations are derived. The velocities of longitudinal and transversal sound waves are found.

  3. Effects of Pulsed Electromagnetic Fields on Osteoporosis Model

    NASA Astrophysics Data System (ADS)

    Xiaowei, Yang; Liming, Wang; Guan, Z. C.; Yaou, Zhang; Xiangpeng, Wang

    The purpose of this paper was to investigate the preventive effects and long term effects of extremely low frequency pulsed electromagnetic fields (PEMFs), generated by circular coils and pulsed electromagnetic fields stimulators, on osteoporosis in bilaterally ovariectomized rats. In preventive experiment, thirty three-month old female Sprague-Dawley rats were randomly divided into three different groups: sham (SHAM), ovariectomy (OVX), PEMFs stimulation (PEMFs). All rats were subjected to bilaterally ovariectomy except those in SHAM group. The PEMFs group was exposed to pulsed electromagnetic fields with frequency 15 Hz, peak magnetic induction density 2.2mT and exposure time 2 hours per day. The bone mineral density (BMD) of vertebra and left femur were measured by dual energy X-ray absorptiometry at eighth week, twelfth week and sixteenth week after surgery. In long term effects experiment, forty four rats were randomly divided into sham (14 rats, SHAM), ovariectomy group (10 rats, OVX), 15Hz PEMFs group(10 rats, 15Hz) and 30Hz PEMFs group(10 rats, 30Hz) at twenty-sixth week after surgery. Rats in PEMFs groups were stimulated sixteen weeks. In preventive experiment, the Corrected BMD of vertebra and femur was significantly higher than that of OVX group after 16 weeks (P<0.001, P<0.001 respectively). In long term effects experiment, the vertebral BMD of 15Hz PEMFs group and 30Hz PEMFs group was significantly higher than that of OVX groups (P<0.01, P<0.05 respectively). The experimental results demonstrated that extremely low intensity, low frequency, single pulsed electromagnetic fields significantly slowed down the loss of corrected vertebral and femoral BMD in bilaterally ovariectomized rats and suggest that PEMFs may be beneficial in the treatment of osteoporosis.

  4. Challenges and Opportunities For Space Plasma Physics in the Use of Electromagnetic Fields Measurements (Invited)

    NASA Astrophysics Data System (ADS)

    Torbert, R. B.; Angelopoulos, V.

    2013-12-01

    This presentation will review recent progress and future challenges in the use of electromagnetic fields measurements for understanding space plasma phenomena. A summary of the performance of the instrumentation on the recently launched Van Allen Probes and the upcoming NASA MMS mission will describe the state-of-the-art in many of these measurements techniques. There will also be speculation on areas of possible future instrument development that will enhance new space missions.

  5. Surface-enhanced Raman scattering spectra of adsorbates on Cu2O nanospheres: charge-transfer and electromagnetic enhancement

    NASA Astrophysics Data System (ADS)

    Jiang, Li; You, Tingting; Yin, Penggang; Shang, Yang; Zhang, Dongfeng; Guo, Lin; Yang, Shihe

    2013-03-01

    Surface-enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) have been investigated on the surface of Cu2O nanospheres. The SERS signals were believed to originate from the static chemical enhancement, resonant chemical enhancement and electromagnetic enhancement. The coupling between the adsorbates and the semiconductor, evidenced by the shift in absorption spectrum of modified Cu2O and the enhancement of non-totally symmetric modes of the 4-MBA and 4-mercaptopyridine (4-MPY) molecules, were invoked to explain the experimental results. Furthermore, simulations were employed to investigate the nature of the enhancement mechanisms operative between the molecules and the semiconductor. Density functional theory (DFT) calculations suggested a charge transfer (CT) transition process between the molecules and the Cu2O nanospheres. Three-dimensional finite-difference time domain (3D-FDTD) simulations were conducted to map out the electromagnetic field around the Cu2O nanospheres. The experimental and simulation results have revealed the promise of the Cu2O nanospheres as a good SERS substrate and the prospect of using the SERS substrate as a valuable tool for in situ investigation and assay of the adsorption behavior on semiconductor surfaces.Surface-enhanced Raman scattering (SERS) spectra of 4-mercaptobenzoic acid (4-MBA) have been investigated on the surface of Cu2O nanospheres. The SERS signals were believed to originate from the static chemical enhancement, resonant chemical enhancement and electromagnetic enhancement. The coupling between the adsorbates and the semiconductor, evidenced by the shift in absorption spectrum of modified Cu2O and the enhancement of non-totally symmetric modes of the 4-MBA and 4-mercaptopyridine (4-MPY) molecules, were invoked to explain the experimental results. Furthermore, simulations were employed to investigate the nature of the enhancement mechanisms operative between the molecules and the semiconductor

  6. Offshore windmills and the effects of electromagnetic fields on fish.

    PubMed

    Ohman, Marcus C; Sigray, Peter; Westerberg, Håkan

    2007-12-01

    With the large scale developments of offshore windpower the number of underwater electric cables is increasing with various technologies applied. A wind farm is associated with different types of cables used for intraturbine, array-to-transformer, and transformer-to-shore transmissions. As the electric currents in submarine cables induce electromagnetic fields there is a concern of how they may influence fishes. Studies have shown that there are fish species that are magneto-sensitive using geomagnetic field information for the purpose of orientation. This implies that if the geomagnetic field is locally altered it could influence spatial patterns in fish. There are also physiological aspects to consider, especially for species that are less inclined to move as the exposure could be persistent in a particular area. Even though studies have shown that magnetic fields could affect fish, there is at present limited evidence that fish are influenced by the electromagnetic fields that underwater cables from windmills generate. Studies on European eel in the Baltic Sea have indicated some minor effects. In this article we give an overview on the type of submarine cables that are used for electric transmissions in the sea. We also describe the character of the magnetic fields they induce. The effects of magnetic fields on fish are reviewed and how this may relate to the cables used for offshore wind power is discussed.

  7. Electromagnetic fields in medicine - The state of art.

    PubMed

    Pasek, Jarosław; Pasek, Tomasz; Sieroń-Stołtny, Karolina; Cieślar, Grzegorz; Sieroń, Aleksander

    2016-01-01

    Intense development of methods belonging to physical medicine has been noted recently. There are treatment methods, which in many cases lead to reduction treatment time and positively influence on quality of life treatment patients. The present physical medicine systematically extends their therapeutic possibilities. This above applies to illnesses and injuries of locomotor system, diseases affecting of soft tissues, as well as chronic wounds. The evidence on this are the results of basic and clinical examinations relating the practical use of electromagnetic fields in medicine. In this work the authors introduced the procedure using the current knowledge relating to physical characteristic and biological effects of the magnetic fields. In the work the following methods were used: static magnetic fields, spatial magnetic fields, the variable magnetic fields both with laser therapy (magnetolaserotherapy) and variable magnetic fields both with light optical non-laser (magnetoledtherapy) talked.

  8. Reflected and refracted electromagnetic fields in a semi-infinite body

    NASA Astrophysics Data System (ADS)

    Apostol, M.; Vaman, G.

    2009-11-01

    We compute the reflected and refracted electromagnetic fields for an ideal semi-infinite body (either a plasma or a dielectric), as well as the reflection coefficient, by using a general approach based on the polarization equation of motion and electromagnetic potentials. The method consists of representing the charge disturbances by a displacement field in the positions of the moving charges. The propagation of an electromagnetic wave in matter is treated by means of the retarded electromagnetic potentials, and the resulting integral equations are solved. Generalized Fresnel's relations are thereby obtained for any incidence angle and polarization and the angles of total polarization and total reflection are derived (the latter for the plasma). Bulk and surface plasmon-polariton modes are also identified for the plasma. As it is well known, the field inside the plasma is either damped (evanescent) or propagating (transparency regime), and the reflection coefficient exhibits an abrupt enhancement on passing from the propagating regime to the damped one (total reflection).

  9. Reconstruction of velocity fields in electromagnetic flow tomography

    PubMed Central

    Lehtikangas, Ossi; Karhunen, Kimmo

    2016-01-01

    Electromagnetic flow meters (EMFMs) are the gold standard in measuring flow velocity in process industry. The flow meters can measure the mean flow velocity of conductive liquids and slurries. A drawback of this approach is that the velocity field cannot be determined. Asymmetric axial flows, often encountered in multiphase flows, pipe elbows and T-junctions, are problematic and can lead to serious systematic errors. Recently, electromagnetic flow tomography (EMFT) has been proposed for measuring velocity fields using several coils and a set of electrodes attached to the surface of the pipe. In this work, a velocity field reconstruction method for EMFT is proposed. The method uses a previously developed finite-element-based computational forward model for computing boundary voltages and a Bayesian framework for inverse problems. In the approach, the vz-component of the velocity field along the longitudinal axis of the pipe is estimated on the pipe cross section. Different asymmetric velocity fields encountered near pipe elbows, solids-in-water flows in inclined pipes and in stratified or multiphase flows are tested. The results suggest that the proposed reconstruction method could be used to estimate velocity fields in complicated pipe flows in which the conventional EMFMs have limited accuracy. This article is part of the themed issue ‘Supersensing through industrial process tomography’. PMID:27185961

  10. Reconstruction of velocity fields in electromagnetic flow tomography.

    PubMed

    Lehtikangas, Ossi; Karhunen, Kimmo; Vauhkonen, Marko

    2016-06-28

    Electromagnetic flow meters (EMFMs) are the gold standard in measuring flow velocity in process industry. The flow meters can measure the mean flow velocity of conductive liquids and slurries. A drawback of this approach is that the velocity field cannot be determined. Asymmetric axial flows, often encountered in multiphase flows, pipe elbows and T-junctions, are problematic and can lead to serious systematic errors. Recently, electromagnetic flow tomography (EMFT) has been proposed for measuring velocity fields using several coils and a set of electrodes attached to the surface of the pipe. In this work, a velocity field reconstruction method for EMFT is proposed. The method uses a previously developed finite-element-based computational forward model for computing boundary voltages and a Bayesian framework for inverse problems. In the approach, the vz-component of the velocity field along the longitudinal axis of the pipe is estimated on the pipe cross section. Different asymmetric velocity fields encountered near pipe elbows, solids-in-water flows in inclined pipes and in stratified or multiphase flows are tested. The results suggest that the proposed reconstruction method could be used to estimate velocity fields in complicated pipe flows in which the conventional EMFMs have limited accuracy. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  11. Surface enhanced Raman optical activity of molecules on orientationally averaged substrates: theory of electromagnetic effects.

    PubMed

    Janesko, Benjamin G; Scuseria, Gustavo E

    2006-09-28

    We present a model for electromagnetic enhancements in surface enhanced Raman optical activity (SEROA) spectroscopy. The model extends previous treatments of SEROA to substrates, such as metal nanoparticles in solution, that are orientationally averaged with respect to the laboratory frame. Our theoretical treatment combines analytical expressions for unenhanced Raman optical activity with molecular polarizability tensors that are dressed by the substrate's electromagnetic enhancements. We evaluate enhancements from model substrates to determine preliminary scaling laws and selection rules for SEROA. We find that dipolar substrates enhance Raman optical activity (ROA) scattering less than Raman scattering. Evanescent gradient contributions to orientationally averaged ROA scale to first or higher orders in the gradient of the incident plane-wave field. These evanescent gradient contributions may be large for substrates with quadrupolar responses to the plane-wave field gradient. Some substrates may also show a ROA contribution that depends only on the molecular electric dipole-electric dipole polarizability. These conclusions are illustrated via numerical calculations of surface enhanced Raman and ROA spectra from (R)-(-)-bromochlorofluoromethane on various model substrates.

  12. Spectrum of classes of point emitters of electromagnetic wave fields.

    PubMed

    Castañeda, Román

    2016-09-01

    The spectrum of classes of point emitters has been introduced as a numerical tool suitable for the design, analysis, and synthesis of non-paraxial optical fields in arbitrary states of spatial coherence. In this paper, the polarization state of planar electromagnetic wave fields is included in the spectrum of classes, thus increasing its modeling capabilities. In this context, optical processing is realized as a filtering on the spectrum of classes of point emitters, performed by the complex degree of spatial coherence and the two-point correlation of polarization, which could be implemented dynamically by using programmable optical devices.

  13. Electromagnetic field properties in the vicinity of a massive wormhole

    SciTech Connect

    Novikov, I. D.; Shatskiy, A. A.

    2011-12-15

    It is proved that not only massless but also traversable massive wormholes can have electromagnetic 'hair.' An analysis is also presented of the passage from a traversable wormhole to the limit of a Reissner-Nordstroem black hole, with the corresponding disappearance of 'hair.' A general method is developed for solving stationary axisymmetric Maxwell's equations in the field of a massive, spherically symmetric wormhole. As a particular example of application of the method, a solution is found to the axisymmetric magnetostatic problem for a current loop in the field of the Bronnikov-Ellis-Morris-Thorne wormhole.

  14. Electromagnetic Field Quantization in Time-Dependent Linear Media

    SciTech Connect

    Pedrosa, I. A.; Rosas, Alexandre

    2009-07-03

    We present a quantization scheme for the electromagnetic field in time-dependent homogeneous nondispersive conducting and nonconducting linear media without sources. Using the Coulomb gauge, we demonstrate this quantization can be mapped into a damped (attenuated) time-dependent quantum harmonic oscillator. Remarkably, we find that the time dependence of the permittivity, for epsilon>0, gives rise to an attenuation of the radiation field. Afterwards, we obtain the exact wave functions for this problem and consider an exponential time accretion of the permittivity as a particular case.

  15. On a remarkable electromagnetic field in the Einstein Universe

    NASA Astrophysics Data System (ADS)

    Kopiński, Jarosław; Natário, José

    2017-06-01

    We present a time-dependent solution of the Maxwell equations in the Einstein universe, whose electric and magnetic fields, as seen by the stationary observers, are aligned with the Clifford parallels of the 3-sphere S^3. The conformal equivalence between Minkowski's spacetime and (a region of) the Einstein cylinder is then exploited in order to obtain a knotted, finite energy, radiating solution of the Maxwell equations in flat spacetime. We also discuss similar electromagnetic fields in expanding closed Friedmann models, and compute the matter content of such configurations.

  16. Electromagnetic field occupational exposure: non-thermal vs. thermal effects.

    PubMed

    Israel, M; Zaryabova, V; Ivanova, M

    2013-06-01

    There are a variety of definitions for "non-thermal effects" included in different international standards. They start by the simple description that they are "effects of electromagnetic energy on a body that are not heat-related effects", passing through the very general definition related to low-level effects: "biological effects ascribed to exposure to low-level electric, magnetic and electromagnetic fields, i.e. at or below the corresponding dosimetric reference levels in the frequency range covered in this standard (0 Hz-300 GHz)", and going to the concrete definition of "the stimulation of muscles, nerves, or sensory organs, vertigo or phosfenes". Here, we discuss what kind of effect does the non-thermal one has on human body and give data of measurements in different occupations with low-frequency sources of electromagnetic field such as electric power distribution systems, transformers, MRI systems and : video display units (VDUs), whereas thermal effects should not be expected. In some of these workplaces, values above the exposure limits could be found, nevertheless that they are in the term "non-thermal effects" on human body. Examples are workplaces in MRI, also in some power plants. Here, we will not comment on non-thermal effects as a result of RF or microwave exposure because there are not proven evidence about the existance of such effects and mechanisms for them are not clear.

  17. Noise induced calcium oscillations in a cell exposed to electromagnetic fields.

    PubMed

    Zhang, Yuhong; Zhao, Yongli; Chen, Yafei; Yuan, Changqing; Zhan, Yong

    2015-01-01

    The effects of noise on the calcium oscillations in a cell exposed to electromagnetic fields are described by a dynamic model. Noise is a very important factor to be considered in the dynamic research on the calcium oscillations in a cell exposed to electromagnetic fields. Some meaningful results have been obtained here based on the discussion. The results show that the pattern of intracellular calcium oscillations exposure to electromagnetic fields can be influenced by noise. Furthermore, the intracellular calcium oscillations exposure to electromagnetic fields can also be induced by noise. And the work has also studied the relationships between the voltage sensitive calcium channel's open probability and electromagnetic field. The result can provide new insights into constructive roles and potential applications of selecting appropriate electromagnetic field frequency during the research of biological effect of electromagnetic field.

  18. Plasma effects in electromagnetic field interaction with biological tissue

    NASA Astrophysics Data System (ADS)

    Sharma, R. P.; Batra, Karuna; Excell, Peter S.

    2011-02-01

    Theoretical analysis is presented of the nonlinear behavior of charge carriers in biological tissue under the influence of varying low-intensity electromagnetic (EM) field. The interaction occurs because of the nonlinear force arising due to the gradient of the EM field intensity acting on free electrons in the conduction band of proteins in metabolically active biological cell membrane receptors leading to a redistribution of charge carriers. Field dependence of the resulting dielectric constant is investigated by a suitable modification to include an additional electronic contribution term to the three-term Debye model. The exogenous EM field propagating in this nonlinear cellular medium satisfies the nonlinear Schrödinger equation and can be affected significantly. Resulting field effect can be substantially augmented and effective rectification/demodulation can occur. Possible implications of this modification on biological processes in white and grey matter are discussed.

  19. Effects of Bluetooth device electromagnetic field on hearing: pilot study.

    PubMed

    Balachandran, R; Prepageran, N; Prepagaran, N; Rahmat, O; Zulkiflee, A B; Hufaida, K S

    2012-04-01

    The Bluetooth wireless headset has been promoted as a 'hands-free' device with a low emission of electromagnetic radiation. To evaluate potential changes in hearing function as a consequence of using Bluetooth devices, by assessing changes in pure tone audiography and distortion production otoacoustic emissions. Prospective study. Thirty adult volunteers were exposed to a Bluetooth headset device (1) on 'standby' setting for 6 hours and (2) at full power for 10 minutes. Post-exposure hearing was evaluated using pure tone audiography and distortion production otoacoustic emission testing. There were no statistically significant changes in hearing, as measured above, following either exposure type. Exposure to the electromagnetic field emitted by a Bluetooth headset, as described above, did not decrease hearing thresholds or alter distortion product otoacoustic emissions.

  20. Work and energy for particles in electromagnetic field

    NASA Astrophysics Data System (ADS)

    Babajanyan, S. G.

    2017-07-01

    Defining the energy and work for particles interacting with electromagnetic field (EMF) is an open problem, because—due to the gauge-freedom—there exist various non-equivalent possibilities. It is argued that a consistent definition can be provided via the Lorenz gauge. To this end, I work out a system of two electromagnetically coupled classical particles. One of them is much heavier and models the source of work. The definition of energy in the Lorenz gauge is causal and consistent, because it leads to an approximate conservation law due to which the work done by the heavy particle (source of work) can be defined either via the kinetic energy of the heavy particle, or via the full time-dependent energy (kinetic + potential in the Lorenz gauge) of the light particle.

  1. Biological effects from electromagnetic field exposure and public exposure standards.

    PubMed

    Hardell, Lennart; Sage, Cindy

    2008-02-01

    During recent years there has been increasing public concern on potential health risks from power-frequency fields (extremely low frequency electromagnetic fields; ELF) and from radiofrequency/microwave radiation emissions (RF) from wireless communications. Non-thermal (low-intensity) biological effects have not been considered for regulation of microwave exposure, although numerous scientific reports indicate such effects. The BioInitiative Report is based on an international research and public policy initiative to give an overview of what is known of biological effects that occur at low-intensity electromagnetic fields (EMFs) exposure. Health endpoints reported to be associated with ELF and/or RF include childhood leukaemia, brain tumours, genotoxic effects, neurological effects and neurodegenerative diseases, immune system deregulation, allergic and inflammatory responses, breast cancer, miscarriage and some cardiovascular effects. The BioInitiative Report concluded that a reasonable suspicion of risk exists based on clear evidence of bioeffects at environmentally relevant levels, which, with prolonged exposures may reasonably be presumed to result in health impacts. Regarding ELF a new lower public safety limit for habitable space adjacent to all new or upgraded power lines and for all other new constructions should be applied. A new lower limit should also be used for existing habitable space for children and/or women who are pregnant. A precautionary limit should be adopted for outdoor, cumulative RF exposure and for cumulative indoor RF fields with considerably lower limits than existing guidelines, see the BioInitiative Report. The current guidelines for the US and European microwave exposure from mobile phones, for the brain are 1.6 W/Kg and 2 W/Kg, respectively. Since use of mobile phones is associated with an increased risk for brain tumour after 10 years, a new biologically based guideline is warranted. Other health impacts associated with exposure to

  2. The universal C*-algebra of the electromagnetic field II. Topological charges and spacelike linear fields

    NASA Astrophysics Data System (ADS)

    Buchholz, Detlev; Ciolli, Fabio; Ruzzi, Giuseppe; Vasselli, Ezio

    2017-02-01

    Conditions for the appearance of topological charges are studied in the framework of the universal C*-algebra of the electromagnetic field, which is represented in any theory describing electromagnetism. It is shown that non-trivial topological charges, described by pairs of fields localised in certain topologically non-trivial spacelike separated regions, can appear in regular representations of the algebra only if the fields depend non-linearly on the mollifying test functions. On the other hand, examples of regular vacuum representations with non-trivial topological charges are constructed, where the underlying field still satisfies a weakened form of "spacelike linearity". Such representations also appear in the presence of electric currents. The status of topological charges in theories with several types of electromagnetic fields, which appear in the short distance (scaling) limit of asymptotically free non-abelian gauge theories, is also briefly discussed.

  3. Effects of electromagnetic fields on fecundity in the chicken.

    PubMed

    Krueger, W F; Giarola, A J; Bradley, J W; Shrekenhamer, A

    1975-02-28

    Egg production was reduced when young laying hens were kept in contact with metal cages while being continuously exposed to the following cw fields: a vhf field at a frequency of 260 MHz, with an incident power that decreased from 100 to 4mW during the experiment; a uhf field at a frequency of 915 MHz, with an incident power of 800 mW during the first 2.5 weeks, zero during the following week, and 200 mW for the remainder of the experiment; a uhf field at 2.435 GHz, with an incident power of 800 mW; an elf electric field at a frequency of 60 Hz, with a calculated value of field strength of 1600 V/m; an elf magnetic field at 60 Hz, with a value of magnetic flux density of 1.4G. With the exception of the hens exposed to the uhf field at 915 MHz, all other treated groups laid significantly less eggs than the controls (p smaller than or equal to 0.01). This reduction (similar 15% less than the controls) began with the first 4-week production period. The egg production curves for the hens exposed to the vhf field at 260 MHz and to the uhf field at 2.435 GHz were approximately the same beginning with the sixth week of production, and they maintained comparable production levels for the remainder of the experiment. An 8% total drop in production also was experienced in the group of birds exposed to the 915-MHz field, which pulsed because of equipment failure. Egg production rate curves for the birds in the elf electric and magnetic fields were substantially different from those exhibited by birds in the other electromagnetic fields. The birds in the E-field regained a production level comparable to the controls after 11 weeks production, whereas those in the B-field dropped to 31% production, which was approximately 40% poorer than the controls by the twelfth week of production. Fertility of cocks and hens was not affected by continuous low-power vhf and uhf near-zone electromagnetic exposure or elf electric or magnetic field treatment. Fertility was exceptionally good

  4. Enhanced Ultra-Wideband (UWB) Circular Monopole Antenna with Electromagnetic Band Gap (EBG) Surface and Director

    DTIC Science & Technology

    2014-08-01

    enhanced UWB monopole antenna 4. Electromagnetic Band Gap Surface (EBG) Design EBG surfaces act as perfect magnetic conductors (PMCs) at a resonance...Enhanced Ultra-Wideband ( UWB ) Circular Monopole Antenna with Electromagnetic Band Gap (EBG) Surface and Director by Amir I Zaghloul, Youn M...DATES COVERED (From - To) 4. TITLE AND SUBTITLE Enhanced Ultra-Wideband ( UWB ) Circular Monopole Antenna with Electromagnetic Band Gap (EBG

  5. Addendum to `numerical modeling of an enhanced very early time electromagnetic (VETEM) prototype system'

    USGS Publications Warehouse

    Cui, T.J.; Chew, W.C.; Aydiner, A.A.; Wright, D.L.; Smith, D.V.; Abraham, J.D.

    2000-01-01

    Two numerical models to simulate an enhanced very early time electromagnetic (VETEM) prototype system that is used for buried-object detection and environmental problems are presented. In the first model, the transmitting and receiving loop antennas accurately analyzed using the method of moments (MoM), and then conjugate gradient (CG) methods with the fast Fourier transform (FFT) are utilized to investigate the scattering from buried conducting plates. In the second model, two magnetic dipoles are used to replace the transmitter and receiver. Both the theory and formulation are correct and the simulation results for the primary magnetic field and the reflected magnetic field are accurate.

  6. Electromagnetic field of a charge traveling into an anisotropic medium.

    PubMed

    Galyamin, Sergey N; Tyukhtin, Andrey V

    2011-11-01

    We analyze the electromagnetic field generated by a point charge intersecting the interface between vacuum and a nonmagnetic anisotropic medium with a plasma-type dispersion of the dielectric permittivity tensor. After penetrating the medium, the charge moves along its main axis. The total field is presented as a sum of a self-field (i.e., a charge field in a corresponding unbounded medium) and a scattered field associated with the boundary influence. We show that the self-field in the considered anisotropic medium is divided into a quasistatic field and a wave field (the so-called "plasma trace" is absent in the case under consideration). Under certain conditions, the Vavilov-Cherenkov radiation generated in the medium is reversed (i.e., the energy flux density vector forms an obtuse angle with the direction of the charge motion). Accordingly, so-called reversed Cherenkov-transition radiation (RCTR) can be generated. We analytically and numerically investigate both the scattered field and the total one, and we show that RCTR exists in the vacuum region if the charge velocity exceeds a certain threshold value associated with total internal reflection. Computations of the Fourier harmonics of the field as well as the total field itself demonstrate that RCTR in vacuum can be a dominant effect. Some properties of RCTR can be useful for diagnostics of particle bunches and determination of medium characteristics.

  7. Electromagnetic field of a charge traveling into an anisotropic medium

    NASA Astrophysics Data System (ADS)

    Galyamin, Sergey N.; Tyukhtin, Andrey V.

    2011-11-01

    We analyze the electromagnetic field generated by a point charge intersecting the interface between vacuum and a nonmagnetic anisotropic medium with a plasma-type dispersion of the dielectric permittivity tensor. After penetrating the medium, the charge moves along its main axis. The total field is presented as a sum of a self-field (i.e., a charge field in a corresponding unbounded medium) and a scattered field associated with the boundary influence. We show that the self-field in the considered anisotropic medium is divided into a quasistatic field and a wave field (the so-called “plasma trace” is absent in the case under consideration). Under certain conditions, the Vavilov-Cherenkov radiation generated in the medium is reversed (i.e., the energy flux density vector forms an obtuse angle with the direction of the charge motion). Accordingly, so-called reversed Cherenkov-transition radiation (RCTR) can be generated. We analytically and numerically investigate both the scattered field and the total one, and we show that RCTR exists in the vacuum region if the charge velocity exceeds a certain threshold value associated with total internal reflection. Computations of the Fourier harmonics of the field as well as the total field itself demonstrate that RCTR in vacuum can be a dominant effect. Some properties of RCTR can be useful for diagnostics of particle bunches and determination of medium characteristics.

  8. Electromagnetic field of a charge traveling into an anisotropic medium

    SciTech Connect

    Galyamin, Sergey N.; Tyukhtin, Andrey V.

    2011-11-15

    We analyze the electromagnetic field generated by a point charge intersecting the interface between vacuum and a nonmagnetic anisotropic medium with a plasma-type dispersion of the dielectric permittivity tensor. After penetrating the medium, the charge moves along its main axis. The total field is presented as a sum of a self-field (i.e., a charge field in a corresponding unbounded medium) and a scattered field associated with the boundary influence. We show that the self-field in the considered anisotropic medium is divided into a quasistatic field and a wave field (the so-called 'plasma trace' is absent in the case under consideration). Under certain conditions, the Vavilov-Cherenkov radiation generated in the medium is reversed (i.e., the energy flux density vector forms an obtuse angle with the direction of the charge motion). Accordingly, so-called reversed Cherenkov-transition radiation (RCTR) can be generated. We analytically and numerically investigate both the scattered field and the total one, and we show that RCTR exists in the vacuum region if the charge velocity exceeds a certain threshold value associated with total internal reflection. Computations of the Fourier harmonics of the field as well as the total field itself demonstrate that RCTR in vacuum can be a dominant effect. Some properties of RCTR can be useful for diagnostics of particle bunches and determination of medium characteristics.

  9. Instability-driven electromagnetic fields in coronal plasmas

    SciTech Connect

    Manuel, M. J.-E.; Li, C. K.; Seguin, F. H.; Sinenian, N.; Frenje, J. A.; Casey, D. T.; Petrasso, R. D.; Hager, J. D.; Betti, R.; Hu, S. X.; Delettrez, J.; Meyerhofer, D. D.

    2013-04-15

    Filamentary electromagnetic fields previously observed in the coronae of laser-driven spherical targets [F. H. S eguin et al., Phys. Plasma. 19, 012701 (2012)] have been further investigated in laser irradiated plastic foils. Face-on proton-radiography provides an axial view of these filaments and shows coherent cellular structure regardless of initial foil-surface conditions. The observed cellular fields are shown to have an approximately constant scale size of 210 lm throughout the plasma evolution. A discussion of possible field-generation mechanisms is provided and it is demonstrated that the likely source of the cellular field structure is the magnetothermal instability. Using predicted temperature and density profiles, the fastest growing modes of this instability were found to be slowly varying in time and consistent with the observed cellular size.

  10. Instability-driven electromagnetic fields in coronal plasmas

    DOE PAGES

    Manuel, M. J.-E.; Li, C. K.; Seguin, F. H.; ...

    2013-04-15

    Filamentary electromagnetic fields previously observed in the coronae of laser-driven spherical targets [F. H. S eguin et al., Phys. Plasma. 19, 012701 (2012)] have been further investigated in laser irradiated plastic foils. Face-on proton-radiography provides an axial view of these filaments and shows coherent cellular structure regardless of initial foil-surface conditions. The observed cellular fields are shown to have an approximately constant scale size of 210 lm throughout the plasma evolution. A discussion of possible field-generation mechanisms is provided and it is demonstrated that the likely source of the cellular field structure is the magnetothermal instability. Using predicted temperature andmore » density profiles, the fastest growing modes of this instability were found to be slowly varying in time and consistent with the observed cellular size.« less

  11. Human disease resulting from exposure to electromagnetic fields.

    PubMed

    Carpenter, David O

    2013-01-01

    Electromagnetic fields (EMFs) include everything from cosmic rays through visible light to the electric and magnetic fields associated with electricity. While the high frequency fields have sufficient energy to cause cancer, the question of whether there are human health hazards associated with communication radiofrequency (RF) EMFs and those associated with use of electricity remains controversial. The issue is more important than ever given the rapid increase in the use of cell phones and other wireless devices. This review summarizes the evidence stating that excessive exposure to magnetic fields from power lines and other sources of electric current increases the risk of development of some cancers and neurodegenerative diseases, and that excessive exposure to RF radiation increases risk of cancer, male infertility, and neurobehavioral abnormalities. The relative impact of various sources of exposure, the great range of standards for EMF exposure, and the costs of doing nothing are also discussed.

  12. ELECTRON HOLOGRAPHY OF ELECTROMAGNETIC FIELDS - RECENT THEORETICAL ADVANCES.

    SciTech Connect

    BELEGGIA,M.; POZZI, G.; TONOMURA, A.

    2007-01-01

    It has been shown in this work that the Fourier space approach can be fruitfully applied to the calculation of the fields and the associated electron optical phase shift of several magnetic and electrostatic structures, like superconducting vortices in conventional and high-T{sub c} superconductors, reverse biased p-n junctions, magnetic domains and nanoparticles. In all these cases, this novel approach has led to unexpected but extremely interesting results, very often expressed in analytical form, which allow the quantitative and reliable interpretation of the experimental data collected by means of electron holography or of more conventional Lorentz microscopy techniques. Moreover, it is worth recalling that whenever long-range electromagnetic fields are involved, a physical model of the object under investigation is necessary in order to take into account correctly the perturbation of the reference wave induced by the tail of the field protruding into the vacuum. For these reasons, we believe that the Fourier space approach for phase computations we have introduced and discussed in this chapter will represent an invaluable tool for the investigation of electromagnetic fields at the meso- and nano-scale.

  13. Cosmological magnetic fields from inflation in extended electromagnetism

    SciTech Connect

    Beltran Jimenez, Jose; Maroto, Antonio L.

    2011-01-15

    In this work we consider an extended electromagnetic theory in which the scalar state which is usually eliminated by means of the Lorenz condition is allowed to propagate. This state has been shown to generate a small cosmological constant in the context of standard inflationary cosmology. Here we show that the usual Lorenz gauge-breaking term now plays the role of an effective electromagnetic current. Such a current is generated during inflation from quantum fluctuations and gives rise to a stochastic effective charge density distribution. Because of the high electric conductivity of the cosmic plasma after inflation, the electric charge density generates currents which give rise to both vorticity and magnetic fields on sub-Hubble scales. Present upper limits on vorticity coming from temperature anisotropies of the CMB are translated into lower limits on the present value of cosmic magnetic fields. We find that, for a nearly scale invariant vorticity spectrum, magnetic fields B{sub {lambda}>}10{sup -12} G are typically generated with coherence lengths ranging from subgalactic scales up to the present Hubble radius. Those fields could act as seeds for a galactic dynamo or even account for observations just by collapse and differential rotation of the protogalactic cloud.

  14. Delineation of electric and magnetic field effects of extremely low frequency electromagnetic radiation on transcription

    SciTech Connect

    Greene, J.J.; Skowronski, W.J.; Mullins, J.M.; Nardone, R.M.; Penafiel, M.; Meister, R. )

    1991-01-31

    The relative effects of the electric and magnetic field components of extremely low frequency electromagnetic radiation (ELF) on transcription were examined in human leukemia HL-60 cells. Delineation of the individual field contributions was achieved by irradiating cells in separate concentric compartments of a culture dish within a solenoid chamber. This exposure system produced a homogeneous magnetic field with a coincident electric field whose strength varied directly with distance from the center of the culture dish. Irradiation of HL-60 cells with sine wave ELF at 60 Hz and a field strength of 10 Gauss produced a transient increase in the transcriptional rates which reached a maximum of 50-60% enhancement at 30-120 minutes of irradiation and declined to near basal levels by 18 hours. Comparison of transcription responses to ELF of cells in different concentric compartments revealed that the transcriptional effects were primarily the result of the electric field component with little or no contribution from the magnetic field.

  15. A review on Electromagnetic fields (EMFs) and the reproductive system

    PubMed Central

    Asghari, Ali; Khaki, Amir Afshin; Rajabzadeh, Asghar; Khaki, Arash

    2016-01-01

    Environmental factors, such as electromagnetic waves, induce biological and genetic effects. One of the most important physiological systems involved with electromagnetic fields (EMFs) is the genital system. This paper reviews the effects of EMFs on human reproductive organs, female animals, fetus development and the importance of two types of natural antioxidants, i.e., vitamin E and fennel. The studies presented in this review referred to the effects of different exposures to EMFs on the reproductive system, and we tried to show the role of natural antioxidants in reducing the effects of the exposures. Many studies have been done on the effects of ionizing and non-ionizing electromagnetic waves on the cell line of spermatogenesis, sexual hormones, and the structure of the testes. Also, about the hormonal cycle, folliculogenesis and female infertility related to EMF have been given more consideration. In particular, attention is directed to pregnant women due to the importance of their fetuses. However, in addition to the studies conducted on animals, further epidemiological research should be conducted. PMID:27648194

  16. A review on Electromagnetic fields (EMFs) and the reproductive system.

    PubMed

    Asghari, Ali; Khaki, Amir Afshin; Rajabzadeh, Asghar; Khaki, Arash

    2016-07-01

    Environmental factors, such as electromagnetic waves, induce biological and genetic effects. One of the most important physiological systems involved with electromagnetic fields (EMFs) is the genital system. This paper reviews the effects of EMFs on human reproductive organs, female animals, fetus development and the importance of two types of natural antioxidants, i.e., vitamin E and fennel. The studies presented in this review referred to the effects of different exposures to EMFs on the reproductive system, and we tried to show the role of natural antioxidants in reducing the effects of the exposures. Many studies have been done on the effects of ionizing and non-ionizing electromagnetic waves on the cell line of spermatogenesis, sexual hormones, and the structure of the testes. Also, about the hormonal cycle, folliculogenesis and female infertility related to EMF have been given more consideration. In particular, attention is directed to pregnant women due to the importance of their fetuses. However, in addition to the studies conducted on animals, further epidemiological research should be conducted.

  17. Dynamics of Cometary Dust Particles in Electromagnetic Radiation Fields

    NASA Astrophysics Data System (ADS)

    Herranen, Joonas; Markkanen, Johannes; Penttilä, Antti; Muinonen, Karri

    2016-10-01

    The formation of cometary dust tails and comae is based on solar radiation pressure. The pressure effects of electromagnetic radiation were originally conceptualized in Kepler's observations of the tails of comets and formulated mathematically by Maxwell in 1873. Today, the dynamics of cometary dust are known to be governed by gravity, electromagnetic forces, drag, solar wind, and solar radiation pressure.Solar radiation pressure has its roots in absorption, emission, and scattering of electromagnetic radiation. Due to modern advances in so-called integral equation methods in electromagnetics, a new approach of studying the effect of radiation pressure on cometary dust dynamics can be constructed. We solve the forces and torques due to radiation pressure for an arbitrarily shaped dust particle using volume integral equation methods.We then present a framework for solving the equations of motion of cometary dust particles due to radiative interactions. The solution is studied in a simplified cometary environment, where the radiative effects are studied at different orbits. The rotational and translational equations of motion are solved directly using a quaternion-based integrator. The rotational and translational equations of motion affect dust particle alignment and concentration. This is seen in the polarization of the coma. Thus, our direct dynamical approach can be used in modelling the observed imaging photo-polarimetry of the coma.In future studies, the integrator can be further extended to an exemplary comet environment, taking into account the drag, and the electric and magnetic fields. This enables us to study the dynamics of a single cometary dust particle based on fundamental physics.Acknowledgments. Research supported, in part, bythe European Research Council (ERC, grant Nr. 320773).

  18. Above-threshold ionization in two electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Bardfield, Rina Shoshana

    1997-11-01

    Above-threshold ionization (ATI) is a process in which a target atom absorbs more than the minimum number of photons from an applied electromagnetic field than are required for ionization, and is characterized by several peaks in the photoelectron spectrum which are separated from each other by the energy of a single photon (Agostini et al. 1979). The experiments of interest in this work involve ATI at microwave frequencies (Gallagher 1988, Gallagher and Scholz 1989), where the frequency of the field is too low to be able to see individual peaks in the spectrum. What is seen is that, in the presence of a weak assisting field, a very large number of microwave photons are absorbed. This problem cannot be treated using standard methods, due both to the intensity of the microwave field and to the large numbers of photons absorbed. The focus of this work is on the development of new analytical techniques to examine the interaction of an atomic system with two simultaneous electromagnetic fields. Specifically, the work focuses on above-threshold ionization in combined microwave and laser fields, where the microwave field is a very strong, very low frequency field, so that standard techniques, such as perturbation theory, do not apply. The work is based on two theoretical methods especially designed for use in intense field problems. These are the Strong Field Approximation (SFA) (Reiss 1980, 1992, 1996), which describes the ionization of an atom by an intense field in which the detached electron remains free in the field after ionization occurs, and the Momentum Translation Approximation (MTA) (Reiss 1970a, 1970b, 1989), which describes the dressing of a bound atomic state by a strong field in which the field can alter the state of the electron without necessarily causing transitions. The laser field, which is much weaker, is treated by traditional techniques. The theory is developed in general terms using S-matrix methods, with particular cases being modeled using

  19. An Optimization of Pulsed ElectroMagnetic Fields Study

    NASA Technical Reports Server (NTRS)

    Goodwin, Thomas J.

    2006-01-01

    To date, in our research we have focused on the use of normal human neuronal progenitor (NHNP) cells because of their importance in human nervous system regeneration, development and maintenance, but we have developed 2-D and 3-D bioreactors that can accommodate any cell line. In this Project, we will include the use of tissues important for physiological regeneration: Human osteoblasts or chondrocytes, and vascular cells. Our initial results with the NHNP cells were quite startling using extremely low-level electromagnetic fields (5 microtesla at 10Hz; 6mA). The low-amplitude, rapidly time-varying electromagnetic fields exert a very potent effect on the proliferation, morphology, and gene expression of the cells in culture, both in standard 2-dimensional culture plates as well as cells organized into 3-dimensional tissue-like assemblies (TLAs) in a 3D bioreactor. We have replicated our preliminary results many, many times, have analyzed the gene expression using gene arrays (followed by Luminex analysis for protein production), and have monitored cell proliferation, orientation, morphology, and glucose metabolism, and we are confident that we have a stable and reliable model to study the control of high-level cellular processes by application of low-amplitude, time varying electromagnetic fields (TVEMF) (1, 2). In additional studies at the University of Michigan, we have been able to generate functional in vitro engineered mammalian skeletal muscle, and have employed nerve-muscle co-culture techniques to promote axonal sprouting. We believe that nearly all tissues, in particular, neural, are susceptible to the influences of low-level TVEMF.

  20. An Optimization of Pulsed ElectroMagnetic Fields Study

    NASA Technical Reports Server (NTRS)

    Goodwin, Thomas J.

    2006-01-01

    To date, in our research we have focused on the use of normal human neuronal progenitor (NHNP) cells because of their importance in human nervous system regeneration, development and maintenance, but we have developed 2-D and 3-D bioreactors that can accommodate any cell line. In this Project, we will include the use of tissues important for physiological regeneration: Human osteoblasts or chondrocytes, and vascular cells. Our initial results with the NHNP cells were quite startling using extremely low-level electromagnetic fields (5 microtesla at 10Hz; 6mA). The low-amplitude, rapidly time-varying electromagnetic fields exert a very potent effect on the proliferation, morphology, and gene expression of the cells in culture, both in standard 2-dimensional culture plates as well as cells organized into 3-dimensional tissue-like assemblies (TLAs) in a 3D bioreactor. We have replicated our preliminary results many, many times, have analyzed the gene expression using gene arrays (followed by Luminex analysis for protein production), and have monitored cell proliferation, orientation, morphology, and glucose metabolism, and we are confident that we have a stable and reliable model to study the control of high-level cellular processes by application of low-amplitude, time varying electromagnetic fields (TVEMF) (1, 2). In additional studies at the University of Michigan, we have been able to generate functional in vitro engineered mammalian skeletal muscle, and have employed nerve-muscle co-culture techniques to promote axonal sprouting. We believe that nearly all tissues, in particular, neural, are susceptible to the influences of low-level TVEMF.

  1. Difficulties in applying numerical simulations to an evaluation of occupational hazards caused by electromagnetic fields.

    PubMed

    Zradziński, Patryk

    2015-01-01

    Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers' exposure to the electromagnetic field have been considered: workers' body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards.

  2. Difficulties in applying numerical simulations to an evaluation of occupational hazards caused by electromagnetic fields

    PubMed Central

    Zradziński, Patryk

    2015-01-01

    Due to the various physical mechanisms of interaction between a worker's body and the electromagnetic field at various frequencies, the principles of numerical simulations have been discussed for three areas of worker exposure: to low frequency magnetic field, to low and intermediate frequency electric field and to radiofrequency electromagnetic field. This paper presents the identified difficulties in applying numerical simulations to evaluate physical estimators of direct and indirect effects of exposure to electromagnetic fields at various frequencies. Exposure of workers operating a plastic sealer have been taken as an example scenario of electromagnetic field exposure at the workplace for discussion of those difficulties in applying numerical simulations. The following difficulties in reliable numerical simulations of workers’ exposure to the electromagnetic field have been considered: workers’ body models (posture, dimensions, shape and grounding conditions), working environment models (objects most influencing electromagnetic field distribution) and an analysis of parameters for which exposure limitations are specified in international guidelines and standards. PMID:26323781

  3. Electromagnetic generation of sound in metals in a magnetic field

    NASA Astrophysics Data System (ADS)

    Aronov, I. E.; Fal'ko, V. L.

    1992-11-01

    A wide range of phenomena of the electromagnetic generation of sound in metals in a magnetic field is reviewed. All phenomena of mutual conversion of waves and of sound generation are due to the interaction of conduction electrons with phonons. A wide variety of resonance effects in a magnetic field determines numerous mechanisms for direct sound generation by an external microwave. The basic equations and boundary conditions for the problem of electron-phonon interaction in metals are presented in the quasiclassical approximation. In the low-temperature region under the conditions of the anomalous skin effect the wave conversion is caused, besides by inductive interaction, also by electron-phonon interaction via the deformation potential. The major conversion mechanism of an electromagnetic wave into sound results in various resonance effects in a magnetic field in conditions of strong spatial dispersion. We present an exact solution of the problem for an alkali metal in a magnetic field normal to the surface. We analyze the asymptotic approximations related with the skin-effect anomaly, the coupling of electromagnetic and acoustic waves in metals, and the role of surface scattering. We study the effect of resonance renormalization of electron-phonon interaction in metals with a complex dispersion law, which results in a partial compensation of resonance singularities and appears in Doppler-shifted cyclotron resonances. The doppleron-phonon resonance and its polarization effects are investigated. The electromagnetic generation of sound in metals in a magnetic field parallel to the surface is due to the additional mechanism of selecting “effective” electrons, where resonance effects are observed. We study geometric and cyclotron resonances, and the resonance coupling of a sound wave with a cyclotron wave. The amplitude and phase of the generated sound depend on the character of electron scattering on the metal boundary because in specular scattering a group of

  4. RF Electromagnetic Field Treatment of Tetragonal Kesterite CZTSSe Light Absorbers.

    PubMed

    Semenenko, Mykola O; Babichuk, Ivan S; Kyriienko, Oleksandr; Bodnar, Ivan V; Caballero, Raquel; Leon, Maximo

    2017-12-01

    In this work, we propose a method to improve electro-optical and structural parameters of light-absorbing kesterite materials. It relies on the application of weak power hydrogen plasma discharges using electromagnetic field of radio frequency range, which improves homogeneity of the samples. The method allows to reduce strain of light absorbers and is suitable for designing solar cells based on multilayered thin film structures. Structural characteristics of tetragonal kesterite Cu2ZnSn(S, Se)4 structures and their optical properties were studied by Raman, infrared, and reflectance spectroscopies. They revealed a reduction of the sample reflectivity after RF treatment and a modification of the energy band structure.

  5. Accuracy Improvement in Magnetic Field Modeling for an Axisymmetric Electromagnet

    NASA Technical Reports Server (NTRS)

    Ilin, Andrew V.; Chang-Diaz, Franklin R.; Gurieva, Yana L.; Il,in, Valery P.

    2000-01-01

    This paper examines the accuracy and calculation speed for the magnetic field computation in an axisymmetric electromagnet. Different numerical techniques, based on an adaptive nonuniform grid, high order finite difference approximations, and semi-analitical calculation of boundary conditions are considered. These techniques are being applied to the modeling of the Variable Specific Impulse Magnetoplasma Rocket. For high-accuracy calculations, a fourth-order scheme offers dramatic advantages over a second order scheme. For complex physical configurations of interest in plasma propulsion, a second-order scheme with nonuniform mesh gives the best results. Also, the relative advantages of various methods are described when the speed of computation is an important consideration.

  6. RF Electromagnetic Field Treatment of Tetragonal Kesterite CZTSSe Light Absorbers

    NASA Astrophysics Data System (ADS)

    Semenenko, Mykola O.; Babichuk, Ivan S.; Kyriienko, Oleksandr; Bodnar, Ivan V.; Caballero, Raquel; Leon, Maximo

    2017-06-01

    In this work, we propose a method to improve electro-optical and structural parameters of light-absorbing kesterite materials. It relies on the application of weak power hydrogen plasma discharges using electromagnetic field of radio frequency range, which improves homogeneity of the samples. The method allows to reduce strain of light absorbers and is suitable for designing solar cells based on multilayered thin film structures. Structural characteristics of tetragonal kesterite Cu2ZnSn(S, Se)4 structures and their optical properties were studied by Raman, infrared, and reflectance spectroscopies. They revealed a reduction of the sample reflectivity after RF treatment and a modification of the energy band structure.

  7. Healing of Chronic Wounds through Systemic Effects of Electromagnetic Fields

    NASA Astrophysics Data System (ADS)

    Cañedo, L.; Trigos, I.; García-Cantú, R.; Godina-Nava, J. J.; Serrano, G.

    2002-08-01

    Extremely low frequency electromagnetic fields (ELF) were configured to interact with peripheral blood mononuclear cells (PBMC). These ELF were applied in the arm to five patients with chronic wounds resistant to medical and surgical treatment. Wound healing began in all patients during the first two weeks after ELF exposure permiting their previously unresponsive chronic wounds to function as internal controls. All lesions were cured or healed >70% in less than four months. Systemic effects were explained by ELF activation of PBMC and their transportation through the blood to the affected site. This therapy is effective in selected patients with chronic wounds.

  8. Finding electromagnetic and chemical enhancement factors of surface-enhanced Raman scattering.

    PubMed

    Dvoynenko, Mykhaylo M; Wang, Juen-Kai

    2007-12-15

    The authors report two methods to determine electromagnetic and chemical enhancement factors in surface-enhanced Raman scattering (SERS), which are based on saturation property and decay dynamics of photoluminescence and concurrent measurements of photoluminescence and resonance Raman scattering intensities. Considerations for experimental implementation are discussed. This study is expected to facilitate the understanding of SERS mechanisms and the advancement of the usage of SERS in chemical and biological sensor applications.

  9. Basics of quantum field theory of electromagnetic interaction processes in single-layer graphene

    NASA Astrophysics Data System (ADS)

    Hieu Nguyen, Van

    2016-09-01

    The content of this work is the study of electromagnetic interaction in single-layer graphene by means of the perturbation theory. The interaction of electromagnetic field with Dirac fermions in single-layer graphene has a peculiarity: Dirac fermions in graphene interact not only with the electromagnetic wave propagating within the graphene sheet, but also with electromagnetic field propagating from a location outside the graphene sheet and illuminating this sheet. The interaction Hamiltonian of the system comprising electromagnetic field and Dirac fermions fields contains the limits at graphene plane of electromagnetic field vector and scalar potentials which can be shortly called boundary electromagnetic field. The study of S-matrix requires knowing the limits at graphene plane of 2-point Green functions of electromagnetic field which also can be shortly called boundary 2-point Green functions of electromagnetic field. As the first example of the application of perturbation theory, the second order terms in the perturbative expansions of boundary 2-point Green functions of electromagnetic field as well as of 2-point Green functions of Dirac fermion fields are explicitly derived. Further extension of the application of perturbation theory is also discussed.

  10. Study on Zeeman-split spoof surface plasmon polaritons by use of spin-sensitive enhanced electromagnetic transmission

    SciTech Connect

    Wu, Li-Ting; Guo, Rui-Peng; Guo, Tian-Jing; Yang, Mu; Cui, Hai-Xu; Cao, Xue-Wei; Chen, Jing

    2014-12-21

    Structured metal surfaces could support spoof surface plasmon polaritons (SPPs), the dispersion of which is determined by the cutoff condition of guided modes in the nanostructures. We show that we can achieve split spoof SPPs by breaking the degeneracy of guided helical modes in concentric nanostructures via the classic analogue of the Zeeman effect. This split effect is shown to be observable from the spectra of enhanced electromagnetic transmission. Spin-sensitive enhanced electromagnetic transmission and the associated characteristics of field are investigated. Transmission branches versus parallel wavevector can be satisfactorily fitted by using the dispersion of spoof SPPs.

  11. Dual-Scattering Near-Field Microscope for Correlative Nanoimaging of SERS and Electromagnetic Hotspots.

    PubMed

    Kusch, Patryk; Mastel, Stefan; Mueller, Niclas S; Morquillas Azpiazu, Nieves; Heeg, Sebastian; Gorbachev, Roman; Schedin, Fredrik; Hübner, Uwe; Pascual, Jose I; Reich, Stephanie; Hillenbrand, Rainer

    2017-04-12

    Surface-enhanced Raman spectroscopy (SERS) enables sensitive chemical studies and materials identification, relying on electromagnetic (EM) and chemical-enhancement mechanisms. Here we introduce a tool for the correlative nanoimaging of EM and SERS hotspots, areas of strongly enhanced EM fields and Raman scattering, respectively. To that end, we implemented a grating spectrometer into a scattering-type scanning near-field optical microscope (s-SNOM) for mapping of both the elastically and inelastically (Raman) scattered light from the near-field probe, that is, a sharp silicon tip. With plasmon-resonant gold dimers (canonical SERS substrates) we demonstrate with nanoscale spatial resolution that the enhanced Raman scattering from the tip is strongly correlated with its enhanced elastic scattering, the latter providing access to the EM-field enhancement at the illumination frequency. Our technique has wide application potential in the correlative nanoimaging of local-field enhancement and SERS efficiency as well as in the investigation and quality control of novel SERS substrates.

  12. Electromagnetic enhancement by a periodic array of nanogrooves in a metallic substrate.

    PubMed

    Zhang, Siwen; Liu, Haitao; Mu, Guoguang

    2011-05-01

    We present comprehensive investigations of the electromagnetic enhancement by a periodic array of rectangular nanogrooves in a metallic substrate. The impacts of array parameters and of illumination conditions on the enhanced electric-field intensity are explored using fully vectorial methods. The calculations are performed mainly for gold and for the visible and infrared wavelengths. The fully vectorial results are reproduced and explained by a simple Fabry-Perot model. Compared with the case of a single groove, the electric-field enhancement of the groove array is found to be much higher by almost 1 order of magnitude, which is shown to be related to the excitation of surface plasmon polaritons with the aid of the model. Practical considerations of a finite groove number and of a finite groove length are also provided.

  13. Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems

    PubMed Central

    Pan, Liang; Huang, Yingzhou; Yang, Yanna; Xiong, Wen; Chen, Guo; Su, Xun; Wei, Hua; Wang, Shuxia; Wen, Weijia

    2015-01-01

    For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p’-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis. PMID:26601698

  14. Electromagnetic field redistribution induced selective plasmon driven surface catalysis in metal nanowire-film systems

    NASA Astrophysics Data System (ADS)

    Pan, Liang; Huang, Yingzhou; Yang, Yanna; Xiong, Wen; Chen, Guo; Su, Xun; Wei, Hua; Wang, Shuxia; Wen, Weijia

    2015-11-01

    For the novel interpretation of Raman spectrum from molecule at metal surface, the plasmon driven surface catalysis (PDSC) reactions have become an interesting topic in the research field of surface enhanced Raman scattering (SERS). In this work, the selective PDSC reactions of p,p’-dimercaptoazobenzene (DMAB) produced from para-aminothiophenol (PATP) or 4-nitrobenzenethiol (4NBT) were demonstrated in the Ag nanowires dimer-Au film systems. The different SERS spectra collected at individual part and adjacent part of the same nanowire-film system pointed out the importance of the electromagnetic field redistribution induced by image charge on film in this selective surface catalysis, which was confirmed by the simulated electromagnetic simulated electro- magnetic field distributions. Our result indicated this electromagnetic field redistribution induced selective surface catalysis was largely affected by the polarization and wavelength of incident light but slightly by the difference in diameters between two nanowires. Our work provides a further understanding of PDSC reaction in metal nanostructure and could be a deep support for the researches on surface catalysis and surface analysis.

  15. Electromagnetic field tapering using all-dielectric gradient index materials

    PubMed Central

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-01-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes. PMID:27464989

  16. Conserved currents for electromagnetic fields in the Kerr spacetime

    NASA Astrophysics Data System (ADS)

    Grant, Alexander; Flanagan, Eanna

    2017-01-01

    For any classical linear Lagrangian field theory, the symplectic product provides a conserved current that is bilinear on the space of solutions. Given a linear mapping from the space of solutions into itself, a ``symmetry operator'', one can therefore generate quadratic conserved currents for any linear classical field theory. We apply this procedure to the case of electromagnetism on a Kerr background, showing that this procedure can generate the conserved currents given by Andersson, Bäckdahl, and Blue, as well as two new conserved currents. These currents reduce to the sum of (positive powers of) the Carter constants of the photons in the geometric optics limit, and generalize the current for scalar fields discovered by Carter. We furthermore show that the fluxes of these new currents through null infinity and the horizon are finite.

  17. Electromagnetic field tapering using all-dielectric gradient index materials.

    PubMed

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-07-28

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

  18. Electromagnetic field tapering using all-dielectric gradient index materials

    NASA Astrophysics Data System (ADS)

    Yi, Jianjia; Piau, Gérard-Pascal; de Lustrac, André; Burokur, Shah Nawaz

    2016-07-01

    The concept of transformation optics (TO) is applied to control the flow of electromagnetic fields between two sections of different dimensions through a tapering device. The broadband performance of the field taper is numerically and experimentally validated. The taper device presents a graded permittivity profile and is fabricated through three-dimensional (3D) polyjet printing technology using low-cost all-dielectric materials. Calculated and measured near-field mappings are presented in order to validate the proposed taper. A good qualitative agreement is obtained between full-wave simulations and experimental tests. Such all-dielectric taper paves the way to novel types of microwave devices that can be easily fabricated through low-cost additive manufacturing processes.

  19. Time dependent electromagnetic fields and 4-dimensional Stokes' theorem

    NASA Astrophysics Data System (ADS)

    Andosca, Ryan; Singleton, Douglas

    2016-11-01

    Stokes' theorem is central to many aspects of physics—electromagnetism, the Aharonov-Bohm effect, and Wilson loops to name a few. However, the pedagogical examples and research work almost exclusively focus on situations where the fields are time-independent so that one need only deal with purely spatial line integrals (e.g., ∮ A . d x ) and purely spatial area integrals (e.g., ∫ ( ∇ × A ) . d a = ∫ B . d a ). Here, we address this gap by giving some explicit examples of how Stokes' theorem plays out with time-dependent fields in a full 4-dimensional spacetime context. We also discuss some unusual features of Stokes' theorem with time-dependent fields related to gauge transformations and non-simply connected topology.

  20. Weak scattering of scalar and electromagnetic random fields

    NASA Astrophysics Data System (ADS)

    Tong, Zhisong

    This dissertation encompasses several studies relating to the theory of weak potential scattering of scalar and electromagnetic random, wide-sense statistically stationary fields from various types of deterministic or random linear media. The proposed theory is largely based on the first Born approximation for potential scattering and on the angular spectrum representation of fields. The main focus of the scalar counterpart of the theory is made on calculation of the second-order statistics of scattered light fields in cases when the scattering medium consists of several types of discrete particles with deterministic or random potentials. It is shown that the knowledge of the correlation properties for the particles of the same and different types, described with the newly introduced pair-scattering matrix, is crucial for determining the spectral and coherence states of the scattered radiation. The approach based on the pair-scattering matrix is then used for solving an inverse problem of determining the location of an "alien" particle within the scattering collection of "normal" particles, from several measurements of the spectral density of scattered light. Weak scalar scattering of light from a particulate medium in the presence of optical turbulence existing between the scattering centers is then approached using the combination of the Born's theory for treating the light interaction with discrete particles and the Rytov's theory for light propagation in extended turbulent medium. It is demonstrated how the statistics of scattered radiation depend on scattering potentials of particles and the power spectra of the refractive index fluctuations of turbulence. This theory is of utmost importance for applications involving atmospheric and oceanic light transmission. The second part of the dissertation includes the theoretical procedure developed for predicting the second-order statistics of the electromagnetic random fields, such as polarization and linear momentum

  1. Computational Electromagnetic Modeling of Optical Responses in Plasmonically Enhanced Nanoscale Devices Fabricated with Nanomasking Technique

    NASA Astrophysics Data System (ADS)

    Novak, Eric; Debu, Desalegn; Saylor, Cameron; Herzog, Joseph

    2015-03-01

    This work computationally explores plasmonic nanoscale devices fabricated with a recently developed nanomasking technique that is based on the self-aligned process. Computational electromagnetic modeling has determined enhancement factors and the plasmonic and optical properties of these structures. The nanomasking technique is a new process that is employed to overcome the resolution limits of traditional electron beam lithography and can also be used to increase resolution in photolithography fabrication as well. This technique can consistently produce accurate features with nanostructures and gaps smaller than 10 nm. These smaller dimensions can allow for increased and more localized plasmonically enhanced electric fields. These unique metal devices encompass tunable, enhanced plasmonic and optical properties that can be useful in a wide range of applications. Finite element methods are used to approximate the electromagnetic responses, giving the ability to alter the designs and dimensions in order to optimize the enhancement. Ultimately, we will fabricate devices and characterize the plasmonic properties with optical techniques, including dark-field spectroscopy, to confirm the properties with the goal of generating more efficient devices.

  2. Robust multiscale field-only formulation of electromagnetic scattering

    NASA Astrophysics Data System (ADS)

    Sun, Qiang; Klaseboer, Evert; Chan, Derek Y. C.

    2017-01-01

    We present a boundary integral formulation of electromagnetic scattering by homogeneous bodies that are characterized by linear constitutive equations in the frequency domain. By working with the Cartesian components of the electric E and magnetic H fields and with the scalar functions (r .E ) and (r .H ) where r is a position vector, the problem can be cast as having to solve a set of scalar Helmholtz equations for the field components that are coupled by the usual electromagnetic boundary conditions at material boundaries. This facilitates a direct solution for the surface values of E and H rather than having to work with surface currents or surface charge densities as intermediate quantities in existing methods. Consequently, our formulation is free of the well-known numerical instability that occurs in the zero-frequency or long-wavelength limit in traditional surface integral solutions of Maxwell's equations and our numerical results converge uniformly to the static results in the long-wavelength limit. Furthermore, we use a formulation of the scalar Helmholtz equation that is expressed as classically convergent integrals and does not require the evaluation of principal value integrals or any knowledge of the solid angle. Therefore, standard quadrature and higher order surface elements can readily be used to improve numerical precision for the same number of degrees of freedom. In addition, near and far field values can be calculated with equal precision, and multiscale problems in which the scatterers possess characteristic length scales that are both large and small relative to the wavelength can be easily accommodated. From this we obtain results for the scattering and transmission of electromagnetic waves at dielectric boundaries that are valid for any ratio of the local surface curvature to the wave number. This is a generalization of the familiar Fresnel formula and Snell's law, valid at planar dielectric boundaries, for the scattering and transmission

  3. Performance enhancement of the NPS Transient Electromagnetic Scattering Laboratory

    NASA Astrophysics Data System (ADS)

    Bresani, Aldo E.

    1991-09-01

    This thesis describes the performance enhancement of the NPS Transient Electromagnetic Scattering Laboratory (TESL) accomplished by replacing the old HP 8349A microwave preamplifier of the dual amplifier configuration with a new Avantek 13533-5-13 GHz amplifier and optimizing the delay line length for the 1-6 GHz amplifier. New Matlab software was developed to process the signals scattered from canonical and complex targets. This software includes a program to calculate the correct delay line length for either amplifier in future modifications. The updated TESL is shown to provide measurements yielding excellent agreement with theoretically predicted responses of canonical targets demonstrating a significant improvement of the signal to noise ratio as compared with the previous configuration. A target library was created to support research in radar target identification based on natural resonances.

  4. MUSIC electromagnetic imaging with enhanced resolution for small inclusions

    NASA Astrophysics Data System (ADS)

    Chen, Xudong; Zhong, Yu

    2009-01-01

    This paper investigates the influence of the test dipole on the resolution of the multiple signal classification (MUSIC) imaging method applied to the electromagnetic inverse scattering problem of determining the locations of a collection of small objects embedded in a known background medium. Based on the analysis of the induced electric dipoles in eigenstates, an algorithm is proposed to determine the test dipole that generates a pseudo-spectrum with enhanced resolution. The amplitudes in three directions of the optimal test dipole are not necessarily in phase, i.e., the optimal test dipole may not correspond to a physical direction in the real three-dimensional space. In addition, the proposed test-dipole-searching algorithm is able to deal with some special scenarios, due to the shapes and materials of objects, to which the standard MUSIC does not apply.

  5. Radio frequency electromagnetic fields: cancer, mutagenesis, and genotoxicity.

    PubMed

    Heynick, Louis N; Johnston, Sheila A; Mason, Patrick A

    2003-01-01

    We present critiques of epidemiologic studies and experimental investigations, published mostly in peer-reviewed journals, on cancer and related effects from exposure to nonionizing electromagnetic fields in the nominal frequency range of 3 kHz to 300 GHz of interest to Subcommittee 4 (SC4) of the International Committee on Electromagnetic Safety (ICES). The major topics discussed are presented under the headings Epidemiologic and Other Findings on Human Exposure, Mammals Exposed In Vivo, Mammalian Live Tissues and Cell Preparations Exposed In Vitro, and Mutagenesis and Genotoxicity in Microorganisms and Fruit Flies. Under each major topic, we present minireviews of papers on various specific endpoints investigated. The section on Epidemiologic and Other Findings on Human Exposure is divided into two subsections, the first on possible carcinogenic effects of exposure from emitters not in physical contact with the populations studied, for example, transmitting antennas and other devices. Discussed in the second subsection are studies of postulated carcinogenic effects from use of mobile phones, with prominence given to brain tumors from use of cellular and cordless telephones in direct physical contact with an ear of each subject. In both subsections, some investigations yielded positive findings, others had negative findings, including papers directed toward experimentally verifying positive findings, and both were reported in a few instances. Further research on various important aspects may resolve such differences. Overall, however, the preponderance of published epidemiologic and experimental findings do not support the supposition that in vivo or in vitro exposures to such fields are carcinogenic.

  6. Quantum Mechanics Action of ELF Electromagnetic Fields on Living Organisms

    NASA Astrophysics Data System (ADS)

    Godina-Nava, J. J.

    2010-10-01

    There is presently an intense discussion if extremely low frequency electromagnetic field (ELF-EMF) exposure has consequences for human health. This include exposure to structures and appliances from this range of frequency in the electromagnetic (EM) spectrum. Biological effects of such exposures have been noted frequently, although the implications for specific health effects is not that clear. The basic interactions mechanisms between such fields and living matter is unknown. Numerous hypotheses have been suggested, although none is convincingly supported by experimental data. Various cellular components, processes, and systems can be affected by EMF exposure. Since it is unlikely that EMF can induce DNA damage directly, most studies have examined EMF effects on the cell membrane level, general and specific gene expression, and signal transduction pathways. Even more, a large number of studies have been performed regarding cell proliferation, cell cycle regulation, cell differentiation, metabolism, and various physiological characteristics of cells. The aim of this letter is present the hypothesis of a possible quantum mechanic effect generated by the exposure of ELF EMF, an event which is compatible with the multitude of effects observed after exposure. Based on an extensive literature review, we suggest that ELF EMF exposure is able to perform such activation restructuring the electronic level of occupancy of free radicals in molecules interacting with DNA structures.

  7. Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

    NASA Astrophysics Data System (ADS)

    Novickij, Vitalij; Grainys, Audrius; Lastauskienė, Eglė; Kananavičiūtė, Rūta; Pamedytytė, Dovilė; Kalėdienė, Lilija; Novickij, Jurij; Miklavčič, Damijan

    2016-09-01

    Electroporation is a phenomenon occurring due to exposure of cells to Pulsed Electric Fields (PEF) which leads to increase of membrane permeability. Electroporation is used in medicine, biotechnology, and food processing. Recently, as an alternative to electroporation by PEF, Pulsed ElectroMagnetic Fields (PEMF) application causing similar biological effects was suggested. Since induced electric field in PEMF however is 2-3 magnitudes lower than in PEF electroporation, the membrane permeabilization mechanism remains hypothetical. We have designed pilot experiments where Saccharomyces cerevisiae and Candida lusitaniae cells were subjected to single 100-250 μs electrical pulse of 800 V with and without concomitant delivery of magnetic pulse (3, 6 and 9 T). As expected, after the PEF pulses only the number of Propidium Iodide (PI) fluorescent cells has increased, indicative of membrane permeabilization. We further show that single sub-millisecond magnetic field pulse did not cause detectable poration of yeast. Concomitant exposure of cells to pulsed electric (PEF) and magnetic field (PMF) however resulted in the increased number PI fluorescent cells and reduced viability. Our results show increased membrane permeability by PEF when combined with magnetic field pulse, which can explain electroporation at considerably lower electric field strengths induced by PEMF compared to classical electroporation.

  8. Electromagnetic dissipation during asymmetric reconnection with a moderate guide field

    NASA Astrophysics Data System (ADS)

    Genestreti, Kevin; Burch, James; Cassak, Paul; Torbert, Roy; Phan, Tai; Ergun, Robert; Giles, Barbara; Russell, Chris; Wang, Shan; Akhavan-Tafti, Mojtaba; Varsani, Ali

    2017-04-01

    We calculate the work done on the plasma by the electromagnetic (EM) field, ⃗Jṡ⃗E', and analyze the related electron currents and electric fields, focusing on a single asymmetric guide field electron diffusion region (EDR) event observed by MMS on 8 December 2015. For this event, each of the four MMS spacecraft observed dissipation of EM energy at the in-plane magnetic null point, though large-scale generation/dissipation was observed inconsistently on the magnetospheric side of the boundary. The current at the null was carried by a beam-like population of magnetosheath electrons traveling anti-parallel to the guide field, whereas the current on the Earthward side of the boundary was carried by crescent-shaped electron distributions. We also analyze the terms in Ohm's law, finding a large residual electric field throughout the EDR, inertial and pressure divergence fields at the null, and pressure divergence fields at the magnetosphere-side EDR. Our analysis of the terms in Ohm's law suggests that the EDR had significant three-dimensional structure.

  9. Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

    PubMed Central

    Novickij, Vitalij; Grainys, Audrius; Lastauskienė, Eglė; Kananavičiūtė, Rūta; Pamedytytė, Dovilė; Kalėdienė, Lilija; Novickij, Jurij; Miklavčič, Damijan

    2016-01-01

    Electroporation is a phenomenon occurring due to exposure of cells to Pulsed Electric Fields (PEF) which leads to increase of membrane permeability. Electroporation is used in medicine, biotechnology, and food processing. Recently, as an alternative to electroporation by PEF, Pulsed ElectroMagnetic Fields (PEMF) application causing similar biological effects was suggested. Since induced electric field in PEMF however is 2–3 magnitudes lower than in PEF electroporation, the membrane permeabilization mechanism remains hypothetical. We have designed pilot experiments where Saccharomyces cerevisiae and Candida lusitaniae cells were subjected to single 100–250 μs electrical pulse of 800 V with and without concomitant delivery of magnetic pulse (3, 6 and 9 T). As expected, after the PEF pulses only the number of Propidium Iodide (PI) fluorescent cells has increased, indicative of membrane permeabilization. We further show that single sub-millisecond magnetic field pulse did not cause detectable poration of yeast. Concomitant exposure of cells to pulsed electric (PEF) and magnetic field (PMF) however resulted in the increased number PI fluorescent cells and reduced viability. Our results show increased membrane permeability by PEF when combined with magnetic field pulse, which can explain electroporation at considerably lower electric field strengths induced by PEMF compared to classical electroporation. PMID:27634482

  10. Electromagnetic field triggered drug and chemical delivery via liposomes

    DOEpatents

    Liburdy, Robert P.

    1993-01-01

    The present invention relates to a system and to a method of delivering a drug to a preselected target body site of a patient, comprising the steps of encapsulating the chemical agent within liposomes, essentially temperature insensitive, i.e. not having a specific predetermined phase transition temperature within the specific temperature range of drug administration; administering the liposomes to the target body site; and subjecting the target body site to nonionizing electromagnetic fields in an area of the preselected target body in order to release said chemical agent from the liposomes at a temperature of between about +10 and 65.degree. C. The invention further relates to the use of said liposomes to bind to the surface of or to enter target tissue or an organ in a living system, and, when subjected to a nonionizing field, to release a drug from the liposomes into the target site.

  11. The dielectric response to the magnetic field of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Mukherjee, Shouvik; Mukhopadhyay, Sourabh; Datta, Prasanta Kumar

    2017-04-01

    Light-matter interaction in transparent dielectrics is revisited, including the magnetic force on bound charges in the Lorentz oscillator model. The parameter ranges of incident radiation and the medium on which the magnetic field of the electromagnetic radiation will have a significant effect are traced using Floquet theory. The analysis reveals that the threshold intensity for a significant response of the magnetic field of the radiation at the second harmonic of the incident radiation can be reduced to {10}12 {{W}}{{cm}}-2 for off resonant and even lower for resonant interaction. This phenomenon has already been observed indirectly in experiments [1, 2]. Induced magnetizing current due to the magnetic force is shown to originate from a modified dielectric response, which may be useful in future magneto-optic devices, solar energy harvesting, and studying the ultrafast dynamics in doped dielectrics.

  12. Acceleration of adiabatic quantum dynamics in electromagnetic fields

    SciTech Connect

    Masuda, Shumpei; Nakamura, Katsuhiro

    2011-10-15

    We show a method to accelerate quantum adiabatic dynamics of wave functions under electromagnetic field (EMF) by developing the preceding theory [Masuda and Nakamura, Proc. R. Soc. London Ser. A 466, 1135 (2010)]. Treating the orbital dynamics of a charged particle in EMF, we derive the driving field which accelerates quantum adiabatic dynamics in order to obtain the final adiabatic states in any desired short time. The scheme is consolidated by describing a way to overcome possible singularities in both the additional phase and driving potential due to nodes proper to wave functions under EMF. As explicit examples, we exhibit the fast forward of adiabatic squeezing and transport of excited Landau states with nonzero angular momentum, obtaining the result consistent with the transitionless quantum driving applied to the orbital dynamics in EMF.

  13. Electromagnetic field limits set by the V-Curve.

    SciTech Connect

    Warne, Larry Kevin; Jorgenson, Roy Eberhardt; Hudson, Howard Gerald

    2014-07-01

    When emitters of electromagnetic energy are operated in the vicinity of sensitive components, the electric field at the component location must be kept below a certain level in order to prevent the component from being damaged, or in the case of electro-explosive devices, initiating. The V-Curve is a convenient way to set the electric field limit because it requires minimal information about the problem configuration. In this report we will discuss the basis for the V-Curve. We also consider deviations from the original V-Curve resulting from inductive versus capacitive antennas, increases in directivity gain for long antennas, decreases in input impedance when operating in a bounded region, and mismatches dictated by transmission line losses. In addition, we consider mitigating effects resulting from limited antenna sizes.

  14. Photon merging and splitting in electromagnetic field inhomogeneities

    NASA Astrophysics Data System (ADS)

    Gies, Holger; Karbstein, Felix; Seegert, Nico

    2016-04-01

    We investigate photon merging and splitting processes in inhomogeneous, slowly varying electromagnetic fields. Our study is based on the three-photon polarization tensor following from the Heisenberg-Euler effective action. We put special emphasis on deviations from the well-known constant field results, also revisiting the selection rules for these processes. In the context of high-intensity laser facilities, we analytically determine compact expressions for the number of merged/split photons as obtained in the focal spots of intense laser beams. For the parameter range of typical petawatt class laser systems as pump and probe, we provide estimates for the numbers of signal photons attainable in an actual experiment. The combination of frequency upshifting, polarization dependence and scattering off the inhomogeneities renders photon merging an ideal signature for the experimental exploration of nonlinear quantum vacuum properties.

  15. Theory of a ring laser. [electromagnetic field and wave equations

    NASA Technical Reports Server (NTRS)

    Menegozzi, L. N.; Lamb, W. E., Jr.

    1973-01-01

    Development of a systematic formulation of the theory of a ring laser which is based on first principles and uses a well-known model for laser operation. A simple physical derivation of the electromagnetic field equations for a noninertial reference frame in uniform rotation is presented, and an attempt is made to clarify the nature of the Fox-Li modes for an open polygonal resonator. The polarization of the active medium is obtained by using a Fourier-series method which permits the formulation of a strong-signal theory, and solutions are given in terms of continued fractions. It is shown that when such a continued fraction is expanded to third order in the fields, the familiar small-signal ring-laser theory is obtained.

  16. Geometric entropy and edge modes of the electromagnetic field

    NASA Astrophysics Data System (ADS)

    Donnelly, William; Wall, Aron C.

    2016-11-01

    We calculate the vacuum entanglement entropy of Maxwell theory in a class of curved spacetimes by Kaluza-Klein reduction of the theory onto a two-dimensional base manifold. Using two-dimensional duality, we express the geometric entropy of the electromagnetic field as the entropy of a tower of scalar fields, constant electric and magnetic fluxes, and a contact term, whose leading-order divergence was discovered by Kabat. The complete contact term takes the form of one negative scalar degree of freedom confined to the entangling surface. We show that the geometric entropy agrees with a statistical definition of entanglement entropy that includes edge modes: classical solutions determined by their boundary values on the entangling surface. This resolves a long-standing puzzle about the statistical interpretation of the contact term in the entanglement entropy. We discuss the implications of this negative term for black hole thermodynamics and the renormalization of Newton's constant.

  17. Near-field electromagnetic theory for thin solar cells.

    PubMed

    Niv, A; Gharghi, M; Gladden, C; Miller, O D; Zhang, X

    2012-09-28

    Current methods for evaluating solar cell efficiencies cannot be applied to low-dimensional structures where phenomena from the realm of near-field optics prevail. We present a theoretical approach to analyze solar cell performance by allowing rigorous electromagnetic calculations of the emission rate using the fluctuation-dissipation theorem. Our approach shows the direct quantification of the voltage, current, and efficiency of low-dimensional solar cells. This approach is demonstrated by calculating the voltage and the efficiency of a GaAs slab solar cell for thicknesses from several microns down to a few nanometers. This example highlights the ability of the proposed approach to capture the role of optical near-field effects in solar cell performance.

  18. Electromagnetic field triggered drug and chemical delivery via liposomes

    DOEpatents

    Liburdy, R.P.

    1993-03-02

    The present invention relates to a system and to a method of delivering a drug to a preselected target body site of a patient, comprising the steps of encapsulating the chemical agent within liposomes, essentially temperature insensitive, i.e. not having a specific predetermined phase transition temperature within the specific temperature range of drug administration; administering the liposomes to the target body site; and subjecting the target body site to nonionizing electromagnetic fields in an area of the preselected target body in order to release the chemical agent from the liposomes at a temperature of between about +10 and 65 C. The invention further relates to the use of the liposomes to bind to the surface of or to enter target tissue or an organ in a living system, and, when subjected to a nonionizing field, to release a drug from the liposomes into the target site.

  19. Interaction of extremely-low-frequency electromagnetic fields with humans

    SciTech Connect

    Tenforde, T.S.

    1991-07-01

    At a macroscopic level, the effects of extremely low frequency (ELF) electromagnetic fields on humans are well understood based on fundamental physical principles, but far less is known about the nature of the interactions at a cellular or molecular level. Current evidence suggests the effects of ELF on cellular biochemistry are due to interactions with the cell membrane. Elucidation of the mechanism that underlies this transmembrane signaling is critical for a molecular-level understanding of ELF field effects. Further research is also required to clarify a possible link between ELF exposure and increased cancer risk, since estimated ELF exposure in occupational or residential settings is much lower that the levels used in laboratory studies. There is a clear need for additional epidemiological research in which qualitative dosimetry is used to characterize ELF exposure and careful attention is given to possible effects of confounding variables. 24 refs.

  20. Relativistic particle acceleration by obliquely propagating electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Villalón, Elena; Burke, William J.

    1987-12-01

    The relativistic equations of motion are analyzed for charged particles in a magnetized plasma and externally imposed electromagnetic fields (ω, k), which have wave vectors k that are at arbitrary angles. The particle energy is obtained from a set of nonlinear differential equations, as a function of time, initial conditions, and cyclotron harmonic numbers. For a given cyclotron resonance, the energy oscillates in time within the limits of a potential well; stochastic acceleration occurs if the widths of different Hamiltonian potentials overlap. The net energy gain for a given harmonic increase with the angle of propagation, and decreases as the magnitude of the wave magnetic field increases. Potential applications of these results to the acceleration of ionsopheric electrons are presented.

  1. Electromagnetic fields and the induction of DNA strand breaks.

    PubMed

    Ruiz-Gómez, Miguel J; Martínez-Morillo, Manuel

    2009-01-01

    The International Agency for Research on Cancer (IARC) has classified the extremely low-frequency (ELF) electromagnetic fields (EMF) as "possible carcinogenic" based on the reported effects. The purpose of this work is to review and compare the recent findings related to the induction of DNA strand breaks (DNA-SB) by magnetic field (MF) exposure. We found 29 studies (genotoxic and epigenetic) about the induction of DNA-SB by MF. 50% showed effect of MF and 50% showed no DNA-SB. Nevertheless, considering only genotoxic or only epigenetic studies, 37.5% and 69.2% found induction of DNA-SB by MF, respectively. In relation to these data it seems that MF could act as a co-inductor of DNA damage rather than as a genotoxic agent per se. Nevertheless, the published results, in some cases conflicting with negative findings, do not facilitate to obtain a common consensus about MF effects and biophysical interaction mechanisms.

  2. Electromagnetic plasma wave emissions from the auroral field lines

    NASA Technical Reports Server (NTRS)

    Gurnett, D. A.

    1977-01-01

    The most important types of auroral radio emissions are reviewed, both from a historical perspective as well as considering the latest results. Particular emphasis is placed on four types of electromagnetic emissions which are directly associated with the plasma on the auroral field lines. These emissions are (1) auroral hiss, (2) saucers, (3) ELF noise bands, and (4) auroral kilometric radiation. Ray tracing and radio direction finding measurements indicate that both the auroral hiss and auroral kilometric radiation are generated along the auroral field lines relatively close to the earth, at radial distances from about 2.5 to 5 R sub e. For the auroral hiss the favored mechanism appears to be amplified Cerenkov radiation. For the auroral kilometric radiation several mechanisms have been proposed, usually involving the intermediate generation of electrostatic waves by the precipitating electrons.

  3. Theory of a ring laser. [electromagnetic field and wave equations

    NASA Technical Reports Server (NTRS)

    Menegozzi, L. N.; Lamb, W. E., Jr.

    1973-01-01

    Development of a systematic formulation of the theory of a ring laser which is based on first principles and uses a well-known model for laser operation. A simple physical derivation of the electromagnetic field equations for a noninertial reference frame in uniform rotation is presented, and an attempt is made to clarify the nature of the Fox-Li modes for an open polygonal resonator. The polarization of the active medium is obtained by using a Fourier-series method which permits the formulation of a strong-signal theory, and solutions are given in terms of continued fractions. It is shown that when such a continued fraction is expanded to third order in the fields, the familiar small-signal ring-laser theory is obtained.

  4. Design of a mobile, homogeneous, and efficient electromagnet with a large field of view for neonatal low-field MRI.

    PubMed

    Lother, Steffen; Schiff, Steven J; Neuberger, Thomas; Jakob, Peter M; Fidler, Florian

    2016-08-01

    In this work, a prototype of an effective electromagnet with a field-of-view (FoV) of 140 mm for neonatal head imaging is presented. The efficient implementation succeeded by exploiting the use of steel plates as a housing system. We achieved a compromise between large sample volumes, high homogeneity, high B0 field, low power consumption, light weight, simple fabrication, and conserved mobility without the necessity of a dedicated water cooling system. The entire magnetic resonance imaging (MRI) system (electromagnet, gradient system, transmit/receive coil, control system) is introduced and its unique features discussed. Furthermore, simulations using a numerical optimization algorithm for magnet and gradient system are presented. Functionality and quality of this low-field scanner operating at 23 mT (generated with 500 W) is illustrated using spin-echo imaging (in-plane resolution 1.6 mm × 1.6 mm, slice thickness 5 mm, and signal-to-noise ratio (SNR) of 23 with a acquisition time of 29 min). B0 field-mapping measurements are presented to characterize the homogeneity of the magnet, and the B0 field limitations of 80 mT of the system are fully discussed. The cryogen-free system presented here demonstrates that this electromagnet with a ferromagnetic housing can be optimized for MRI with an enhanced and homogeneous magnetic field. It offers an alternative to prepolarized MRI designs in both readout field strength and power use. There are multiple indications for the clinical medical application of such low-field devices.

  5. Assessment of the Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields

    DTIC Science & Technology

    2003-06-01

    the Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields 5c. PROGRAM ELEMENT NUMBER 5d. PROJECT NUMBER 5d. TASK NUMBER 6. AUTHOR(S) Dr... Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields (EMFs) (From 1 June 2002 to 31 May 2003 for 12 months) Nikolai Konstantinovich Chemeris...International Science and Technology Center (ISTC), Moscow. 2 ISTC 2350 Assessment of the Genotoxic Effects of High Peak-Power Pulsed Electromagnetic Fields

  6. A. A. Ukhtomskii's dominance principle of brain activity in the perception of electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Kholodov, Yu. A.

    1994-01-01

    Preliminary instruction of the subject plays an important role in the perception of weak electromagnetic fields acting on the hand. Active attention to a potential effect amplifies a brain state that can be called caution dominance and arises spontaneously with a “placebo” or an electromagnetic field. The radar principle of brain operation is discussed among the physiological mechanisms through which electromagnetic fields act on an organism.

  7. A. A. Ukhtomskii`s dominance principle of brain activity in the perception of electromagnetic fields

    SciTech Connect

    Kholodov, Yu.A.

    1994-07-01

    Preliminary instruction of the subject plays an important role in the perception of weak electromagnetic fields acting on the hand. Active attention to a potential effect amplifies a brain state that can be called caution dominance and arises spontaneously with a {open_quotes}placebo{close_quotes} or an electromagnetic field. The radar principle of brain operation is discussed among the physiological mechanisms through which electromagnetic fields act on an organism.

  8. Cell membrane thermal gradients induced by electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Garner, Allen L.; Deminsky, Maxim; Bogdan Neculaes, V.; Chashihin, V.; Knizhnik, Andrey; Potapkin, Boris

    2013-06-01

    While electromagnetic fields induce structural changes in cell membranes, particularly electroporation, much remains to be understood about membrane level temperature gradients. For instance, microwaves induce cell membrane temperature gradients (∇T) and bioeffects with little bulk temperature change. Recent calculations suggest that nanosecond pulsed electric fields (nsPEFs) may also induce such gradients that may additionally impact the electroporation threshold. Here, we analytically and numerically calculate the induced ∇T as a function of pulse duration and pulse repetition rate. We relate ∇T to the thermally induced cell membrane electric field (Em) by assuming the membrane behaves as a thermoelectric such that Em ˜ ∇T. Focusing initially on applying nsPEFs to a uniform membrane, we show that reducing pulse duration and increasing pulse repetition rate (or using higher frequency for alternating current (AC) fields) maximizes the magnitude and duration of ∇T and, concomitantly, Em. The maximum ∇T initially occurs at the interface between the cell membrane and extracellular fluid before becoming uniform across the membrane, potentially enabling initial molecular penetration and subsequent transport across the membrane. These results, which are equally applicable to AC fields, motivate further studies to elucidate thermoelectric behavior in a model membrane system and the coupling of the Em induced by ∇T with that created directly by the applied field.

  9. Simultaneous Electromagnetic Tracking and Calibration for Dynamic Field Distortion Compensation.

    PubMed

    Sadjadi, Hossein; Hashtrudi-Zaad, Keyvan; Fichtinger, Gabor

    2016-08-01

    Electromagnetic (EM) tracking systems are highly susceptible to field distortion. The interference can cause measurement errors up to a few centimeters in clinical environments, which limits the reliability of these systems. Unless corrected for, this measurement error imperils the success of clinical procedures. It is therefore fundamental to dynamically calibrate EM tracking systems and compensate for measurement error caused by field distorting objects commonly present in clinical environments. We propose to combine a motion model with observations of redundant EM sensors and compensate for field distortions in real time. We employ a simultaneous localization and mapping technique to accurately estimate the pose of the tracked instrument while creating the field distortion map. We conducted experiments with six degrees-of-freedom motions in the presence of field distorting objects in research and clinical environments. We applied our approach to improve the EM tracking accuracy and compared our results to a conventional sensor fusion technique. Using our approach, the maximum tracking error was reduced by 67% for position measurements and by 64% for orientation measurements. Currently, clinical applications of EM trackers are hampered by the adverse distortion effects. Our approach introduces a novel method for dynamic field distortion compensation, independent from preoperative calibrations or external tracking devices, and enables reliable EM navigation for potential applications.

  10. Extremely Low Frequency Electromagnetic Field in Mesenchymal Stem Cells Gene Regulation: Chondrogenic Markers Evaluation.

    PubMed

    Kavand, Hanie; Haghighipour, Nooshin; Zeynali, Bahman; Seyedjafari, Ehsan; Abdemami, Baharak

    2016-10-01

    There is little evidence demonstrating the effects of electromagnetic fields (EMFs) generated within the biological entity and the effect of extrinsic fields on cellular programing. Taking the path of the more studied stimuli into attention, mechanical forces, it could be understood that nonchemical factors play a consequential role in transcriptional regulatory networks. Cartilaginous tissue consists of collagen protein that is considered as a piezoelectric substrate and is influenced by electric fields making chondrogenic specific genes an exciting candidate for bioelectromagnetic studies. As electromagnetic properties highly depend on the frequencies applied, this study delves into the ability of two EMFs with the frequency of 25 Hz and 50 Hz in inducing SOX9 and COL2 gene expressions in a three-dimensional (3D) mesenchymal stem cell (MSC)-alginate construct. Cell-alginate beads were divided into six groups and treated for a time period of 21 days. To determine the results, qualitative and quantitative data were both reviewed. On observation of real-time polymerase chain reaction (PCR) data, it was apparent that TGF-β1 treatment had a greater COL2 and SOX9 gene expression impact on MSCs compared to pulsed electromagnetic field (PEMF) treatments alone. COL2 was shown to have a greater transcriptional tendency to PEMF, whereas under defined electromagnetic parameters applied in this study, no significant difference was detected in SOX9 gene expressions compared to the control group. PEMF co-treatments enhanced the deposition of extracellular matrix molecules, as the matrix-rich beads were positively stained by Alcian blue. This genre of study is the venue for the control and healing of connective tissue defects.

  11. Nonresonant 104 Terahertz Field Enhancement with 5-nm Slits

    PubMed Central

    Suwal, Om Krishna; Rhie, Jiyeah; Kim, Nayeon; Kim, Dai-Sik

    2017-01-01

    Transmission of Terahertz (THz) electromagnetic wave through a substrate is encumbered because of scattering, multiple reflections, absorption, and Fabry–Perot effects when the wave interacts with the substrate. We present the experimental realization of nonresonant electromagnetic field enhancement by a factor of almost 104 in substrate-free 5-nm gold nanoslits. Our nanoslits yielded greater than 90% normalized electric field transmission in the low-frequency THz region; the slit width was 5 nm, and the gap coverage ratio was 10−4 of the entire membrane, 0.42 mm2. This large field enhancement was attributed to gap plasmons generated by the THz wave, which squeezes the charge cross-section, thus enabling very highly dense oscillating charges and strong THz field transmission from the nanoslits. PMID:28368048

  12. Effects of Pulse Electromagnetic Field on Corrosion Resistance of Al-5 % Cu Alloy

    NASA Astrophysics Data System (ADS)

    Wang, B.; Tang, L. D.; Qi, J. G.; Wang, J. Z.

    2013-03-01

    It was investigated that corrosion resistance of Al-5 % Cu alloy was influenced by pulse electromagnetic field (PEMF). The morphologies were observed by scanning election microscopy (SEM). The corrosion behaviors were investigated by potentiodynamic polarization tests and immersion tests. The results indicated that corrosion resistance of samples could be increased by using pulse electromagnetic field, moreover, the optimum parameter of pulse electromagnetic field in this experiment was showed as follows: 500 V, 3 Hz, 30 s. Decreasing the quantity of eutectic in grain boundaries and refining the grains were main causations for increasing corrosion resistance of Al-5 % Cu alloy with pulse electromagnetic field.

  13. Impact of the strong electromagnetic field on the QCD effective potential for homogeneous Abelian gluon field configurations

    SciTech Connect

    Galilo, Bogdan V.; Nedelko, Sergei N.

    2011-11-01

    The one-loop quark contribution to the QCD effective potential for the homogeneous Abelian gluon field in the presence of an external strong electromagnetic field is evaluated. The structure of extrema of the potential as a function of the angles between chromoelectric, chromomagnetic, and electromagnetic fields is analyzed. In this setup, the electromagnetic field is considered as an external one while the gluon field represents domain structured nonperturbative gluon configurations related to the QCD vacuum in the confinement phase. Two particularly interesting gluon configurations, (anti-)self-dual and crossed orthogonal chromomagnetic and chromoelectric fields, are discussed specifically. Within this simplified framework it is shown that the strong electromagnetic fields can play a catalyzing role for a deconfinement transition. At the qualitative level, the present consideration can be seen as a highly simplified study of an impact of the electromagnetic fields generated in relativistic heavy ion collisions on the strongly interacting hadronic matter.

  14. Quantum diffusion of electromagnetic fields of ultrarelativistic spin-half particles

    NASA Astrophysics Data System (ADS)

    Peroutka, Balthazar; Tuchin, Kirill

    2017-10-01

    We compute electromagnetic fields created by a relativistic charged spin-half particle in empty space at distances comparable to the particle Compton wavelength. The particle is described as a wave packet evolving according to the Dirac equation. It produces the electromagnetic field that is essentially different from the Coulomb field due to the quantum diffusion effect.

  15. Probing intergalactic magnetic fields with simulations of electromagnetic cascades

    NASA Astrophysics Data System (ADS)

    Alves Batista, Rafael; Saveliev, Andrey; Sigl, Günter; Vachaspati, Tanmay

    2016-10-01

    We determine the effect of intergalactic magnetic fields on the distribution of high-energy gamma rays by performing three-dimensional Monte Carlo simulations of the development of gamma-ray-induced electromagnetic cascades in the magnetized intergalactic medium. We employ the so-called "Large Sphere Observer" method to efficiently simulate blazar gamma ray halos. We study magnetic fields with a Batchelor spectrum and with maximal left- and right-handed helicities. We also consider the case of sources whose jets are tilted with respect to the line of sight. We verify the formation of extended gamma ray halos around the source direction, and observe spiral-like patterns if the magnetic field is helical. We apply the Q -statistics to the simulated halos to extract their spiral nature and also propose an alternative method, the S -statistics. Both methods provide a quantitative way to infer the helicity of the intervening magnetic fields from the morphology of individual blazar halos for magnetic field strengths B ≳10-15 G and magnetic coherence lengths Lc≳100 Mpc . We show that the S -statistics has a better performance than the Q -statistics when assessing magnetic helicity from the simulated halos.

  16. Setting prudent public health policy for electromagnetic field exposures.

    PubMed

    Carpenter, David O; Sage, Cindy

    2008-01-01

    Electromagnetic fields (EMF) permeate our environment, coming both from such natural sources as the sun and from manmade sources like electricity, communication technologies and medical devices. Although life on earth would not be possible without sunlight, increasing evidence indicates that exposures to the magnetic fields associated with electricity and to communication frequencies associated with radio, television, WiFi technology, and mobile cellular phones pose significant hazards to human health. The evidence is strongest for leukemia from electricity-frequency fields and for brain tumors from communication-frequency fields, yet evidence is emerging for an association with other diseases as well, including neurodegenerative diseases. Some uncertainty remains as to the mechanism(s) responsible for these biological effects, and as to which components of the fields are of greatest importance. Nevertheless, regardless of whether the associations are causal, the strengths of the associations are sufficiently strong that in the opinion of the authors, taking action to reduce exposures is imperative, especially for the fetus and children. Inaction is not compatible with the Precautionary Principle, as enunciated by the Rio Declaration. Because of ubiquitous exposure, the rapidly expanding development of new EMF technologies and the long latency for the development of such serious diseases as brain cancers, the failure to take immediate action risks epidemics of potentially fatal diseases in the future.

  17. Electromagnetic Form Factors of Hadrons in Quantum Field Theories

    SciTech Connect

    Dominguez, C. A.

    2008-10-13

    In this talk, recent results are presented of calculations of electromagnetic form factors of hadrons in the framework of two quantum field theories (QFT), (a) Dual-Large N{sub c} QCD (Dual-QCD{sub {infinity}}) for the pion, proton, and {delta}(1236), and (b) the Kroll-Lee-Zumino (KLZ) fully renormalizable Abelian QFT for the pion form factor. Both theories provide a QFT platform to improve on naive (tree-level) Vector Meson Dominance (VMD). Dual-QCD{sub {infinity}} provides a tree-level improvement by incorporating an infinite number of zero-width resonances, which can be subsequently shifted from the real axis to account for the time-like behaviour of the form factors. The renormalizable KLZ model provides a QFT improvement of VMD in the framework of perturbation theory. Due to the relative mildness of the {rho}{pi}{pi} coupling, and the size of loop suppression factors, the perturbative expansion is well defined in spite of this being a strong coupling theory. Both approaches lead to considerable improvements of VMD predictions for electromagnetic form factors, in excellent agreement with data.

  18. [Methods of dosimetry in evaluation of electromagnetic fields' biological action].

    PubMed

    Rubtsova, N B; Perov, S Iu

    2012-01-01

    Theoretical and experimental dosimetry can be used for adequate evaluation of the effects of radiofrequency electromagnetic fields. In view of the tough electromagnetic environment in aircraft, pilots' safety is of particular topicality. The dosimetric evaluation is made from the quantitative characteristics of the EMF interaction with bio-objects depending on EM energy absorption in a unit of tissue volume or mass calculated as a specific absorbed rate (SAR) and measured in W/kg. Theoretical dosimetry employs a number of computational methods to determine EM energy, as well as the augmented method of boundary conditions, iterative augmented method of boundary conditions, moments method, generalized multipolar method, finite-element method, time domain finite-difference method, and hybrid methods combining several decision plans modeling the design philosophy of navigation, radiolocation and human systems. Because of difficulties with the experimental SAR estimate, theoretical dosimetry is regarded as the first step in analysis of the in-aircraft conditions of exposure and possible bio-effects.

  19. Electromagnetic field strength levels surrounding electronic article surveillance (EAS) systems.

    PubMed

    Harris, C; Boivin, W; Boyd, S; Coletta, J; Kerr, L; Kempa, K; Aronow, S

    2000-01-01

    Electronic article surveillance (EAS) is used in many applications throughout the world to prevent theft. EAS systems produce electromagnetic (EM) energy around exits to create an EM interrogation zone through which protected items must pass before leaving the establishment. Specially designed EAS tags are attached to these items and must either be deactivated or removed prior to passing through the EAS EM interrogation zone to prevent the alarm from sounding. Recent reports in the scientific literature have noted the possibility that EM energy transmitted by EAS systems may interfere with the proper operation of sensitive electronic medical devices. The Food and Drug Administration has the regulatory responsibility to ensure the safety and effectiveness of medical devices. Because of the possibility of electromagnetic interference (EMI) between EAS systems and electronic medical devices, in situ measurements of the electric and magnetic fields were made around various types of EAS systems. Field strength levels were measured around four types of EAS systems: audio frequency magnetic, pulsed magnetic resonant, radio frequency, and microwave. Field strengths from these EAS systems varied with magnetic fields as high as 1073.6 Am(-1) (in close proximity to the audio frequency magnetic EAS system towers), and electric fields up to 23.8 Vm(-1) (in close proximity to the microwave EAS system towers). Medical devices are only required to withstand 3 Vm(-1) by the International Electrotechnical Commission's current medical device standards. The modulation scheme of the signal transmitted by some types of EAS systems (especially the pulsed magnetic resonant) has been shown to be more likely to cause EMI with electronic medical devices. This study complements other work in the field by attaching specific characteristics to EAS transmitted EM energy. The quantitative data could be used to relate medical device EMI with specific field strength levels and signal waveforms

  20. Simultaneous observations of subauroral electron temperature enhancements and electromagnetic ion cyclotron waves

    NASA Technical Reports Server (NTRS)

    Erlandson, R. E.; Aggson, T. L.; Hogey, W. R.; Slavin, J. A.

    1993-01-01

    Observational results from an investigation of LF (0.5-4.0 Hz) electromagnetic ion cyclotron waves and subauroral electron temperature enhancements recorded from the DE-2 satellite are presented. Four different wave events were analyzed, all recorded at magnetic latitudes from 57-60 deg, magnetic local times from 8-14 hr, and altitudes from 600-900 km. The peak wave amplitudes during the events ranged from 8-70 nT and 5-30 mV/m in the magnetic and electric field, respectively. Te enhancements at the time of the waves were observed in three of four events. A linear relationship between the wave magnetic field spectral density and Te enhancements was found for these events. The Te enhancements were also correlated with an enhanced flux of low energy electrons. During one event (82104) an enhanced flux of electrons were observed at energies up to 50 eV and at nearly all pitch angles, although the flux was largest in the precipitating and upflowing directions. It is suggested that the waves are responsible for heating the low energy electrons which precipitate to the ionosphere and produce the observed Te enhancements. The upflowing electron population appears to be heated at ionospheric altitudes, below the DE-2 satellite.

  1. Field Enhancement using Noble Metal Structures

    NASA Astrophysics Data System (ADS)

    Liu, Benliang

    Resonance may be one of the most fundamental rules of nature. Electromagnetic resonance at nanometer scale could produce a giant field enhancement at optical frequency, providing a way to measure and control the process of atoms and molecules at single molecule scale. For example, the giant field enhancement would provide single molecule sensitivity for Raman scattering, which provides unique tools in measuring the quantity in extremely low concentration. In addition, light-emitting diodes could have high brightness but low input power that would be revolutionary in the optoelectronic industry. Although light enhancement is promising in several key technology areas, there are several challenges remain to be tackled. In particular, since the field enhancement is so strongly geometry dependent that slight modification of the geometry can lead to large variations in the outcome, a thorough understanding in how the geometry of the structure affects the field enhancement and creating proper methods to fabricate these structures reproducibly is of most importance. This thesis is devoted to design, fabrication and characterization of field enhancement generated on the surface of noble metals such as silver or gold with 1D structure. The s-polarized field enhancement arising from one-dimensional metal gratings is designed and optimized by using Rigorous Coupling Wave Analysis (RCWA). After optimization, the strongest enhancement factor is found to be 9.7 for 514nm wavelength light. The theoretical results arc confirmed by angle-dependent reflectivity measurements and the experimental results are found to support the theory. A novel single slit structure employing surface plasmon polaritons (SPPs) for enhancing the electric field is studied. SPPs are first generated on a 50 nm thick metal film using attenuated total reflection coupling, and they are subsequently coupled to the cavity mode induced by the single slit. As a result, the field enhancement is found at least 3

  2. Full scale modeling of an antenna in offshore environment for electromagnetic enhanced oil recovery

    NASA Astrophysics Data System (ADS)

    Kashif, Muhammad; Yahya, Noorhana; Nasir, Nadeem; Akhtar, Majid Niaz; Zaid, Hasnah Mohd; Shafie, Afza

    2012-09-01

    In enhanced oil recovery, high frequency electromagnetic waves are used to heat the oil reservoir and for this purpose an antenna is inserted in a borehole close to the production well. It requires a large numbers of boreholes for the antenna to get uniform heating. In case of offshore these problem can be avoided if a horizontal antenna is towed close to the seabed which maximize the electromagnetic energy transferred from the overburden to reservoir. For this purpose new twin collinear dipole antenna with a total length equal to one wavelength is designed and full scale modeling in offshore environment was done by using computer simulation technology (CST) software. Electromagnetic response of oil reservoir by using new antenna is studied for a model consisting of a 100 m thick oil reservoir having resistivity of 100 ohm-m, buried at a depth of 1000m in overburden with 1000m seawater. It was observed that new antenna gave 365% higher electric field than half wavelength dipole antenna at the far source receiver offset. At the target depth of 2500m new antenna gave 336% more electric field magnitude as compared to half wavelength antenna. In the response of different frequencies of new antenna, electric field value 8.18E-07 V/m at low frequency (0.125Hz) is more than 5.79E-42 V/m at frequency (10KHz). Magnetic field value 5.81E-05 A/m at low frequency (0.125Hz) is more than 1.74E-39 A/m at frequency (10KHz). It was investigated twin collinear dipole antenna produced stronger electric and magnetic fields as compared to half wavelength dipole antenna in offshore environment.

  3. Evaluation of three-dimensional anisotropic head model for mapping realistic electromagnetic fields of brain tissues

    NASA Astrophysics Data System (ADS)

    Jeong, Woo Chul; Wi, Hun; Sajib, Saurav Z. K.; Oh, Tong In; Kim, Hyung Joong; Kwon, Oh In; Woo, Eung Je

    2015-08-01

    Electromagnetic fields provide fundamental data for the imaging of electrical tissue properties, such as conductivity and permittivity, in recent magnetic resonance (MR)-based tissue property mapping. The induced voltage, current density, and magnetic flux density caused by externally injected current are critical factors for determining the image quality of electrical tissue conductivity. As a useful tool to identify bio-electromagnetic phenomena, precise approaches are required to understand the exact responses inside the human body subject to an injected currents. In this study, we provide the numerical simulation results of electromagnetic field mapping of brain tissues using a MR-based conductivity imaging method. First, we implemented a realistic three-dimensional human anisotropic head model using high-resolution anatomical and diffusion tensor MR images. The voltage, current density, and magnetic flux density of brain tissues were imaged by injecting 1 mA of current through pairs of electrodes on the surface of our head model. The current density map of anisotropic brain tissues was calculated from the measured magnetic flux density based on the linear relationship between the water diffusion tensor and the electrical conductivity tensor. Comparing the current density to the previous isotropic model, the anisotropic model clearly showed the differences between the brain tissues. This originates from the enhanced signals by the inherent conductivity contrast as well as the actual tissue condition resulting from the injected currents.

  4. Using strong electromagnetic fields to control x-ray processes.

    SciTech Connect

    Young, L.; Buth, C.; Dunford, R. W.; Ho, P.; Kanter, E. P.; Kraessig, B.; Peterson, E. R.; Rohringer, N.; Santra, R.; Southworth, S. H.

    2010-06-01

    Exploration of a new ultrafast-ultrasmall frontier in atomic and molecular physics has begun. Not only is is possible to control outer-shell electron dynamics with intense ultrafast optical lasers, but now control of inner-shell processes has become possible by combining intense infrared/optical lasers with tunable sources of X-ray radiation. This marriage of strong-field laser and X-ray physics has led to the discovery of methods to control reversibly resonant X-ray absorption in atoms and molecules on ultrafast timescales. Using a strong optical dressing field, resonant X-ray absorption in atoms can be markedly suppressed, yielding an example of electromagnetically induced transparency for x rays. Resonant X-ray absorption can also be controlled in molecules using strong non-resonant, polarized laser fields to align the framework of a molecule, and therefore its unoccupied molecular orbitals to which resonant absorption occurs. At higher laser intensities, ultrafast field ionization produces an irreversible change in X-ray absorption. Finally, the advent of X-ray free electron lasers enables first exploration of non-linear X-ray processes.

  5. [Effects of radiofrequency electromagnetic fields on mammalian spermatogenesis].

    PubMed

    Susa, Martina; Pavicić, Ivan

    2007-12-01

    This article reviews studies about the effects of radiofrequency electromagnetic (RF EM) fields on male reproductive system and reproductive health in mammals. According to current data, there are almost 4 million active mobile phone lines in Croatia while this number has risen to 2 billion in the world. Increased use of mobile technology raises scientific and public concern about possible hazardous effects of RF fields on human health. The effects of radiofrequencies on reproductive health and consequences for the offspring are still mainly unknown. A number of in vivo and in vitro studies indicated that RF fields could interact with charged intracellular macromolecular structures. Results of several laboratory studies on animal models showed how the RF fields could affect the mammalian reproductive system and sperm cells. Inasmuch as, in normal physiological conditions spermatogenesis is a balanced process of division, maturation and storage of cells, it is particularly vulnerable to the chemical and physical environmental stimuli. Especially sensitive could be the cytoskeleton, composed of charged proteins; actin, intermedial filaments and microtubules. Cytoskeleton is a functional and structural part of the cell that has important role in the sperm motility, and is actively involved in the morphologic changes that occur during mammalian spermiogenesis.

  6. Equations of a moving mirror and the electromagnetic field

    NASA Astrophysics Data System (ADS)

    Octavio Castaños, Luis; Weder, Ricardo

    2015-06-01

    We consider a system composed of a mobile slab and the electromagnetic field. We assume that the slab is made of a material that has the following properties when it is at rest: it is linear, isotropic, non-magnetizable, and ohmic with zero free charge density. Using instantaneous Lorentz transformations, we deduce the set of self-consistent equations governing the dynamics of the system and we obtain approximate equations to first order in the velocity and the acceleration of the slab. As a consequence of the motion of the slab, the field must satisfy a wave equation with damping and slowly varying coefficients plus terms that are small when the time-scale of the evolution of the mirror is much larger than that of the field. Also, the motion of the slab and its interaction with the field introduce two effects in the slab’s equation of motion. The first one is a position- and time-dependent mass related to the effective mass taken in phenomenological treatments of this type of systems. The second one is a velocity-dependent force that can give rise to friction and that is related to the much sought cooling of mechanical objects.

  7. Coherent electromagnetic field imaging through Fourier transform heterodyne

    SciTech Connect

    Cooke, B.J.; Laubscher, B.E.; Olivas, N.L.; Goeller, R.M.; Cafferty, M.; Briles, S.D.; Galbraith, A.E. |; Grubler, A.C. |

    1998-12-31

    The authors present a detection process capable of directly imaging the transverse amplitude, phase, and if desired, Doppler shift of coherent electromagnetic fields. Based on coherent detection principles governing conventional heterodyned RADAR/LIDAR systems, Fourier Transform Heterodyne (FTH) incorporates transverse spatial encoding of the local oscillator for image capture. Appropriate selection of spatial encoding functions, or basis set, allows image retrieval by way of classic Fourier manipulations. Of practical interest: (1) imaging is accomplished on a single element detector requiring no additional scanning or moving components, and (2) a wide variety of appropriate spatial encoding functions exist that may be adaptively configured in real-time for applications requiring optimal detection. In this paper, they introduce the underlying principles governing FTH imaging, followed by demonstration of concept via a simple experimental setup based on a HeNe laser and a 69 element spatial phase modulator.

  8. Finite element modeling of electromagnetic fields and waves using NASTRAN

    NASA Technical Reports Server (NTRS)

    Moyer, E. Thomas, Jr.; Schroeder, Erwin

    1989-01-01

    The various formulations of Maxwell's equations are reviewed with emphasis on those formulations which most readily form analogies with Navier's equations. Analogies involving scalar and vector potentials and electric and magnetic field components are presented. Formulations allowing for media with dielectric and conducting properties are emphasized. It is demonstrated that many problems in electromagnetism can be solved using the NASTRAN finite element code. Several fundamental problems involving time harmonic solutions of Maxwell's equations with known analytic solutions are solved using NASTRAN to demonstrate convergence and mesh requirements. Mesh requirements are studied as a function of frequency, conductivity, and dielectric properties. Applications in both low frequency and high frequency are highlighted. The low frequency problems demonstrate the ability to solve problems involving media inhomogeneity and unbounded domains. The high frequency applications demonstrate the ability to handle problems with large boundary to wavelength ratios.

  9. Electromagnetic field energy density in homogeneous negative index materials.

    PubMed

    Shivanand; Webb, Kevin J

    2012-05-07

    An exact separation of both electric and magnetic energies into stored and lost energies is shown to be possible in the special case when the wave impedance is independent of frequency. A general expression for the electromagnetic energy density in such a dispersive medium having a negative refractive index is shown to be accurate in comparison with numerical results. Using an example metamaterial response that provides a negative refractive index, it is shown that negative time-averaged stored energy can occur. The physical meaning of this negative energy is explained as the energy temporarily borrowed by the field from the material. This observation for negative index materials is of interest when approaching properties for a perfect lens. In the broader context, the observation of negative stored energy is of consequence in the study of dispersive materials.

  10. Electromagnetic pulse (EMP), Part I: Effects on field medical equipment

    SciTech Connect

    Vandre, R.H.; Klebers, J.; Tesche, F.M.; Blanchard, J.P. )

    1993-04-01

    The electromagnetic pulse (EMP) from a high-altitude nuclear detonation has the potential to cover an area as large as the continental United States with damaging levels of EMP radiation. In this study, two of seven items of medical equipment were damaged by an EMP simulator. Computer circuit analysis of 17 different items showed that 11 of the 17 items would be damaged by current surges on the power cords, while two would be damaged by current surges on external leads. This research showed that a field commander can expect approximately 65% of his electronic medical equipment to be damaged by a single nuclear detonation as far as 2,200 km away.

  11. Annals of conflicting results: looking back on electromagnetic field research.

    PubMed

    Schoen, D

    1996-11-15

    Few environmental health issues are as contentious as the question of whether exposure to electromagnetic fields (EMFs) from power lines increases cancer risk. Among the many actors in this controversy, epidemiologists have played the leading role in raising the question and motivating research. Epidemiologic studies of the effects of exposure to power-line EMFs include the investigation by Dr. Gilles Thériault and colleagues into incidence rates of cancer among electric-utility workers in Quebec, Ontario and France. With the development of personal dosimeters to measure exposure to electric, magnetic and pulsed EMFs, occupational studies in the 1990s have made an important methodologic advance. But, as Thériault explains, improvements in assessing exposure have not yet translated into clear and consistent findings.

  12. Human exposure to radiofrequency electromagnetic fields. Final rule.

    PubMed

    2013-06-04

    This document resolves several issues regarding compliance with the Federal Communications Commission's (FCC's) regulations for conducting environmental reviews under the National Environmental Policy Act (NEPA) as they relate to the guidelines for human exposure to RF electromagnetic fields. More specifically, the Commission clarifies evaluation procedures and references to determine compliance with its limits, including specific absorption rate (SAR) as a primary metric for compliance, consideration of the pinna (outer ear) as an extremity, and measurement of medical implant exposure. The Commission also elaborates on mitigation procedures to ensure compliances with its limits, including labeling and other requirements for occupational exposure classification, clarification of compliance responsibility at multiple transmitter sites, and labeling of fixed consumer transmitters.

  13. Surface plasmon field enhancements in deterministic aperiodic structures.

    PubMed

    Shugayev, Roman

    2010-11-22

    In this paper we analyze optical properties and plasmonic field enhancements in large aperiodic nanostructures. We introduce extension of Generalized Ohm's Law approach to estimate electromagnetic properties of Fibonacci, Rudin-Shapiro, cluster-cluster aggregate and random deterministic clusters. Our results suggest that deterministic aperiodic structures produce field enhancements comparable to random morphologies while offering better understanding of field localizations and improved substrate design controllability. Generalized Ohm's law results for deterministic aperiodic structures are in good agreement with simulations obtained using discrete dipole method.

  14. Paternal occupational exposure to electromagnetic fields and neuroblastoma in offspring

    SciTech Connect

    Wilkins, J.R. 3d.; Hundley, V.D. )

    1990-06-01

    Investigators in Texas have reported an association between paternal employment in jobs linked with exposure to electromagnetic fields and risk of neuroblastoma in offspring. In an attempt to replicate this finding, the authors conducted a case-control study in Ohio. A total of 101 incident cases of neuroblastoma were identified through the Columbus (Ohio) Children's Hospital Tumor Registry. All cases were born sometime during the period 1942-1967. From a statewide roster of birth certificates, four controls were selected for each case, with individual matching on the case's year of birth, race, and sex, and the mother's county of residence at the time of the (index) child's birth. Multiple definitions were employed to infer the potential for paternal occupational exposure to electromagnetic fields from the industry/occupation statements on the birth certificates. Case-control comparisons revealed adjusted odds ratios ranging in magnitude from 0.5 to 1.9. For two of the exposure definitions employed--both of which are similar to one used by the Texas investigators--the corresponding odds ratios were modestly elevated (odds ratios = 1.6 and 1.9). Notably, the magnitude of these odds ratios is not inconsistent with the Texas findings, where the exposure definition referred to yielded an odds ratio of 2.1. Because the point estimates in this study are imprecise, and because the biologic plausibility of the association is uncertain, the results reported here must be interpreted cautiously. However, the apparent consistency between two independent studies suggests that future evaluation of the association is warranted.

  15. Electromagnetic interference with cardiac pacemakers and implantable cardioverter-defibrillators from low-frequency electromagnetic fields in vivo.

    PubMed

    Tiikkaja, Maria; Aro, Aapo L; Alanko, Tommi; Lindholm, Harri; Sistonen, Heli; Hartikainen, Juha E K; Toivonen, Lauri; Juutilainen, Jukka; Hietanen, Maila

    2013-03-01

    Electromagnetic interference (EMI) can pose a danger to workers with pacemakers and implantable cardioverter-defibrillators (ICDs). At some workplaces electromagnetic fields are high enough to potentially inflict EMI. The purpose of this in vivo study was to evaluate the susceptibility of pacemakers and ICDs to external electromagnetic fields. Eleven volunteers with a pacemaker and 13 with an ICD were exposed to sine, pulse, ramp, and square waveform magnetic fields with frequencies of 2-200 Hz using Helmholtz coil. The magnetic field flux densities varied to 300 µT. We also tested the occurrence of EMI from an electronic article surveillance (EAS) gate, an induction cooktop, and a metal inert gas (MIG) welding machine. All pacemakers were tested with bipolar settings and three of them also with unipolar sensing configurations. None of the bipolar pacemakers or ICDs tested experienced interference in any of the exposure situations. The three pacemakers with unipolar settings were affected by the highest fields of the Helmholtz coil, and one of them also by the EAS gate and the welding cable. The induction cooktop did not interfere with any of the unipolarly programmed pacemakers. Magnetic fields with intensities as high as those used in this study are rare even in industrial working environments. In most cases, employees can return to work after implantation of a bipolar pacemaker or an ICD, after an appropriate risk assessment. Pacemakers programmed to unipolar configurations can cause danger to their users in environments with high electromagnetic fields, and should be avoided, if possible.

  16. Near-field thermal radiation between homogeneous dual uniaxial electromagnetic metamaterials

    SciTech Connect

    Chang, Jui-Yung; Basu, Soumyadipta; Yang, Yue; Wang, Liping

    2016-06-07

    Recently, near-field thermal radiation has attracted much attention in several fields since it can exceed the Planck blackbody limit through the coupling of evanescent waves. In this work, near-field radiative heat transfer between two semi-infinite dual uniaxial electromagnetic metamaterials with two different material property sets is theoretically analyzed. The near-field radiative heat transfer is calculated using fluctuational electrodynamics incorporated with anisotropic wave optics. The underlying mechanisms, namely, magnetic hyperbolic mode, magnetic surface polariton, electrical hyperbolic mode, and electrical surface polariton, between two homogeneous dual uniaxial electromagnetic metamaterials are investigated by examining the transmission coefficient and the spectral heat flux. The effect of vacuum gap distance is also studied, which shows that the enhancement at smaller vacuum gap is mainly due to hyperbolic mode and surface plasmon polariton modes. In addition, the results show that the contribution of s-polarized waves is significant and should not be excluded due to the strong magnetic response regardless of vacuum gap distances. The fundamental understanding and insights obtained here will facilitate the finding and application of novel materials for near-field thermal radiation.

  17. Do the standard expressions for the electromagnetic field momentum need any modifications?

    NASA Astrophysics Data System (ADS)

    Singal, Ashok K.

    2016-10-01

    We investigate here the question raised in the literature about the correct expression for the electromagnetic field momentum, especially when static or stationary fields are involved. For this, we examine a couple of simple but intriguing cases. First, we consider a system configuration in which electromagnetic field momentum is present even though the system is stationary. We trace the electromagnetic momentum to be present in the form of a continuous transport of electromagnetic energy from one part of the system to another, without causing any net change in the energy of the system. In a second case, we show that the electromagnetic momentum is zero irrespective of whether the charged system is static or in motion, even though the electromagnetic energy is present throughout. We demonstrate that the conventional formulation of electromagnetic field momentum describes the systems consistently without any real contradictions. Here, we also make exposition of a curiosity where electromagnetic energy decreases when the charged system gains velocity. Then we discuss the more general question that has been raised: Are the conventional formulas for energy-momentum of electromagnetic fields valid for all cases? Specifically, in the case of so-called "bound fields," do we need to change to some modified definitions? We show that in all cases it is only the conventional formulas that lead to results consistent with the rest of physics, including the special theory of relativity, and that any proposed modifications are thus superfluous.

  18. Electromagnetic field and cylindrical compact objects in modified gravity

    NASA Astrophysics Data System (ADS)

    Yousaf, Z.; Bhatti, M. Zaeem ul Haq

    2016-05-01

    In this paper, we have investigated the role of different fluid parameters particularly electromagnetic field and f(R) corrections on the evolution of cylindrical compact object. We have explored the modified field equations, kinematical quantities and dynamical equations. An expression for the mass function has been found in comparison with the Misner-Sharp formalism in modified gravity, after which different mass-radius diagrams are drawn. The coupled dynamical transport equation have been formulated to discuss the role of thermoinertial effects on the inertial mass density of the cylindrical relativistic interior. Finally, we have presented a framework, according to which all possible solutions of the metric f(R)-Maxwell field equations coupled with static fluid can be written through set of scalar functions. It is found that modified gravity induced by Lagrangians f(R) = αR2, f(R) = αR2 - βR and f(R)=α R^2-β R/1+γ R are likely to host more massive cylindrical compact objects with smaller radii as compared to general relativity.

  19. Analyzing Exposures to Electromagnetic Fields in an Intensive Care Unit

    PubMed Central

    Gökmen, Necati; Erdem, Sabri; Toker, Kadir Atilla; Öçmen, Elvan; Gökmen, Başak Ilgım; Özkurt, Ahmet

    2016-01-01

    Objective In this study, we conducted a numerical analysis of exposure to electromagnetic fields (EMFs) in a hospital’s intensive care unit that is one of the most crucial one in terms of hazardous areas among all service units. This is a new study for measuring exposure to EMFs in an intensive care unit as well as other healthcare services in Turkey. Methods We measured the EMFs in the intensive care unit with a SRM-3006 (selective radiation metre), which was used for measurement of the absolute and the limit values of high frequency EMFs. The measurement points were chosen to represent the highest levels of exposure to which a person might be subjected. We obtained a dataset that included 5929 observations, with 96 extreme values, through measuring the magnetic field in terms of V/m. Results The measurements show the frequency varies from 47 MHz to 2.5 GHz as 17 frequency ranges at the measurement point as well. According to these findings, the referenced maximum safety limit was not exceeded. However, it was also found that mobile telecommunication was the most critical cause of magnetic fields. Conclusion Further studies need to be performed with different frequency antennas to assess the EMFs in intensive care units. PMID:27909603

  20. Singularities in the Transverse Fields of Electromagnetic Waves. II. Observations on the Electric Field

    NASA Astrophysics Data System (ADS)

    Hajnal, J. V.

    1987-12-01

    Electromagnetic waves propagating in free space contain three kinds of singularities called C lines, S surfaces and disclinations. The paper describes observations of these singularities in two different monochromatic microwave fields. The observations confirm all the theoretically predicted properties of the singularities that could be tested. As expected, the singularities were found to be prominent structural features of the fields and in consequence to provide an economical means of characterizing their structure. A notable result is the observation of both right-hand and left-hand C lines in a field that is nominally uniformly left-hand circularly polarized. This is in agreement with the previous assertion that, in general, electromagnetic wavefields contain both right-hand and left-hand polarized regions.

  1. The use of the rotating electromagnetic field for hardening treatment of details

    NASA Astrophysics Data System (ADS)

    Lebedev, V. A.; Kochubey, A. A.; Kiricheck, A. V.

    2017-02-01

    The article discusses energy aspects of details’ hardening with convective flows of freely moving indenters under the conditions of the rotating electromagnetic field. Results of theoretical studies of the kinetics of the movement of the ferromagnetic indenters are presented and the energy model of the state of the rotating magnetic liquefied layer is proposed, formed under the influence of the rotating electromagnetic field.

  2. Spontaneous topological transitions of electromagnetic fields in spatially inhomogeneous C P -odd domains

    NASA Astrophysics Data System (ADS)

    Tuchin, Kirill

    2016-12-01

    Metastable C P -odd domains of the hot QCD matter are coupled to QED via the chiral anomaly. The topology of electromagnetic field in these domains is characterized by magnetic helicity. It is argued, using the Maxwell-Chern-Simons model, that spatial inhomogeneity of the domains induces spontaneous transitions of electromagnetic field between the opposite magnetic helicity states.

  3. Pulsed electromagnetic field: an organic compatible method to promote plant growth and yield in two corn types.

    PubMed

    Bilalis, Dimitrios J; Katsenios, Nikolaos; Efthimiadou, Aspasia; Karkanis, Anestis

    2012-12-01

    Pre-sowing treatment of pulsed electromagnetic fields was used in corn seeds, in both indoor and outdoor conditions, in order to investigate the effect on plant growth and yield. The results of this research showed that pulsed electromagnetic fields can enhance plant characteristics, both under controlled environmental conditions and uncontrolled field conditions. The two varieties responded differently in the duration of magnetic field. Seeds were treated for 0, 15, 30, and 45 min with pulsed electromagnetic field (MF-0, MF-15, MF-30, and MF-45). Common corn variety performed better results in MF-30 treatment, while sweet corn variety performed better in MF-45 treatment. Magnetic field improved germination percentage, vigor, chlorophyll content, leaf area, plant fresh and dry weight, and finally yields. In the very interesting measurement of yield, seeds that have been exposed to magnetic field for 30 and 45 min have been found to perform the best results with no statistical differences among them. Another interesting finding was in root dry weight measurements, where magnetic field has a negative impact in MF-30 treatment in both hybrids, however without affecting other measurements. Enhancements on plant characteristics with economic impact on producer's income could be the future of a modern, organic, and sustainable agriculture.

  4. Modeling of interactions of electromagnetic fields with human bodies

    NASA Astrophysics Data System (ADS)

    Caputa, Krzysztof

    Interactions of electromagnetic fields with the human body have been a subject of scientific interest and public concern. In recent years, issues in power line field effects and those of wireless telephones have been in the forefront of research. Engineering research compliments biological investigations by quantifying the induced fields in biological bodies due to exposure to external fields. The research presented in this thesis aims at providing reliable tools, and addressing some of the unresolved issues related to interactions with the human body of power line fields and fields produced by handheld wireless telephones. The research comprises two areas, namely development of versatile models of the human body and their visualisation, and verification and application of numerical codes to solve selected problems of interest. The models of the human body, which are based on the magnetic resonance scans of the body, are unique and differ considerably from other models currently available. With the aid of computer software developed, the models can be arranged to different postures, and medical devices can be accurately placed inside them. A previously developed code for modeling interactions of power line fields with biological bodies has been verified by rigorous, quantitative inter-laboratory comparison for two human body models. This code has been employed to model electromagnetic interference (EMI) of the magnetic field with implanted cardiac pacemakers. In this case, the correct placement and representation of the pacemaker leads are critical, as simplified computations have been shown to result in significant errors. In modeling interactions of wireless communication devices, the finite difference time domain technique (FDTD) has become a de facto standard. The previously developed code has been verified by comparison with the analytical solution for a conductive sphere. While previously researchers limited their verifications to principal axes of the sphere

  5. Idiopathic environmental intolerance attributed to electromagnetic fields (formerly 'electromagnetic hypersensitivity'): An updated systematic review of provocation studies.

    PubMed

    Rubin, G James; Nieto-Hernandez, Rosa; Wessely, Simon

    2010-01-01

    Idiopathic Environmental Intolerance attributed to electromagnetic fields (IEI-EMF; formerly 'electromagetic hypersensitivity') is a medically unexplained illness in which subjective symptoms are reported following exposure to electrical devices. In an earlier systematic review, we reported data from 31 blind provocation studies which had exposed IEI-EMF volunteers to active or sham electromagnetic fields and assessed whether volunteers could detect these fields or whether they reported worse symptoms when exposed to them. In this article, we report an update to that review. An extensive literature search identified 15 new experiments. Including studies reported in our earlier review, 46 blind or double-blind provocation studies in all, involving 1175 IEI-EMF volunteers, have tested whether exposure to electromagnetic fields is responsible for triggering symptoms in IEI-EMF. No robust evidence could be found to support this theory. However, the studies included in the review did support the role of the nocebo effect in triggering acute symptoms in IEI-EMF sufferers. Despite the conviction of IEI-EMF sufferers that their symptoms are triggered by exposure to electromagnetic fields, repeated experiments have been unable to replicate this phenomenon under controlled conditions. A narrow focus by clinicians or policy makers on bioelectromagnetic mechanisms is therefore, unlikely to help IEI-EMF patients in the long-term.

  6. Exposure to electromagnetic fields aboard high-speed electric multiple unit trains.

    PubMed

    Niu, D; Zhu, F; Qiu, R; Niu, Q

    2016-01-01

    High-speed electric multiple unit (EMU) trains generate high-frequency electric fields, low-frequency magnetic fields, and high-frequency wideband electromagnetic emissions when running. Potential human health concerns arise because the electromagnetic disturbances are transmitted mainly into the car body from windows, and from there to passengers and train staff. The transmission amount and amplitude distribution characteristics that dominate electromagnetic field emission need to be studied, and the exposure level of electromagnetic field emission to humans should be measured. We conducted a series of tests of the on board electromagnetic field distribution on several high-speed railway lines. While results showed that exposure was within permitted levels, the possibility of long-term health effects should be investigated.

  7. Three-dimensional electromagnetic breathers in carbon nanotubes with the field inhomogeneity along their axes

    NASA Astrophysics Data System (ADS)

    Zhukov, Alexander V.; Bouffanais, Roland; Fedorov, Eduard G.; Belonenko, Mikhail B.

    2013-10-01

    We study the propagation of extremely short electromagnetic three-dimensional bipolar pulses in an array of semiconductor carbon nanotubes. The heterogeneity of the pulse field along the axis of the nanotubes is accounted for the first time. The evolution of the electromagnetic field and the charge density of the sample are described by Maxwell's equations supplemented by the continuity equation. Our analysis reveals for the first time the possibility of propagation of three-dimensional electromagnetic breathers in CNTs arrays. Specifically, we found that the propagation of short electromagnetic pulse induces a redistribution of the electron density in the sample.

  8. Electromagnetically induced transparency resonances inverted in magnetic field

    SciTech Connect

    Sargsyan, A.; Sarkisyan, D. E-mail: david@ipr.sci.am; Pashayan-Leroy, Y.; Leroy, C.; Cartaleva, S.; Wilson-Gordon, A. D.; Auzinsh, M.

    2015-12-15

    The phenomenon of electromagnetically induced transparency (EIT) is investigated in a Λ-system of the {sup 87}Rb D{sub 1} line in an external transverse magnetic field. Two spectroscopic cells having strongly different values of the relaxation rates γ{sub rel} are used: an Rb cell with antirelaxation coating (L ∼ 1 cm) and an Rb nanometric- thin cell (nanocell) with a thickness of the atomic vapor column L = 795 nm. For the EIT in the nanocell, we have the usual EIT resonances characterized by a reduction in the absorption (dark resonance (DR)), whereas for the EIT in the Rb cell with an antirelaxation coating, the resonances demonstrate an increase in the absorption (bright resonances (BR)). We suppose that such an unusual behavior of the EIT resonances (i.e., the reversal of the sign from DR to BR) is caused by the influence of an alignment process. The influence of alignment strongly depends on the configuration of the coupling and probe frequencies as well as on the configuration of the magnetic field.

  9. Adaptive framework for uncertainty analysis in electromagnetic field measurements.

    PubMed

    Prieto, Javier; Alonso, Alonso A; de la Rosa, Ramón; Carrera, Albano

    2015-04-01

    Misinterpretation of uncertainty in the measurement of the electromagnetic field (EMF) strength may lead to an underestimation of exposure risk or an overestimation of required measurements. The Guide to the Expression of Uncertainty in Measurement (GUM) has internationally been adopted as a de facto standard for uncertainty assessment. However, analyses under such an approach commonly assume unrealistic static models or neglect relevant prior information, resulting in non-robust uncertainties. This study proposes a principled and systematic framework for uncertainty analysis that fuses information from current measurements and prior knowledge. Such a framework dynamically adapts to data by exploiting a likelihood function based on kernel mixtures and incorporates flexible choices of prior information by applying importance sampling. The validity of the proposed techniques is assessed from measurements performed with a broadband radiation meter and an isotropic field probe. The developed framework significantly outperforms GUM approach, achieving a reduction of 28% in measurement uncertainty. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  10. Electromagnetic cascades and the depletion of intense fields

    NASA Astrophysics Data System (ADS)

    Bulanov, Stepan; Seipt, Daniel; Heinzl, Thomas; Marklund, Mattias; Ji, Qing; Steinke, Sven; Schroeder, Carl; Esarey, Eric; Leemans, Wim P.

    2016-10-01

    The interaction of electrons, positrons, and photons with intense electromagnetic fields gives rise to multi-photon Compton and Breit-Wheeler processes. It is shown that electrons and/or positrons undergo a cascade-type process involving multiple emissions of photons. These photons can consequently convert into electron-positron pairs. As a result charged particles quickly lose their energy developing an exponentially decaying energy distribution. Moreover the multi-photon nature of Compton and Breit-Wheeler processes implies the absorption of a significant number of photons. As a result, the interaction of a highly charged electron bunch with an intense laser pulse can lead to a significant depletion of the laser pulse energy, thus rendering the external field approximation invalid. The relevance of these results to the proposed BELLA-i beamline at BELLA center at LBNL is discussed. We acknowledge support from the Office of Science of the US DOE under Contract No. DE-AC02-05CH11231.

  11. Error sources affecting thermocouple thermometry in RF electromagnetic fields.

    PubMed

    Chakraborty, D P; Brezovich, I A

    1982-03-01

    Thermocouple thermometry errors in radiofrequency (typically 13, 56 MHZ) electromagnetic fields such as are encountered in hyperthermia are described. RF currents capacitatively or inductively coupled into the thermocouple-detector circuit produce errors which are a combination of interference, i.e., 'pick-up' error, and genuine rf induced temperature changes at the junction of the thermocouple. The former can be eliminated by adequate filtering and shielding; the latter is due to (a) junction current heating in which the generally unequal resistances of the thermocouple wires cause a net current flow from the higher to the lower resistance wire across the junction, (b) heating in the surrounding resistive material (tissue in hyperthermia), and (c) eddy current heating of the thermocouple wires in the oscillating magnetic field. Low frequency theories are used to estimate these errors under given operating conditions and relevant experiments demonstrating these effects and precautions necessary to minimize the errors are described. It is shown that at 13.56 MHz and voltage levels below 100 V rms these errors do not exceed 0.1 degrees C if the precautions are observed and thermocouples with adequate insulation (e.g., Bailey IT-18) are used. Results of this study are being currently used in our clinical work with good success.

  12. Convective heat transfer in engine coolers influenced by electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Karcher, C.; Kühndel, J.

    2017-08-01

    In engine coolers of off-highway vehicles, convective heat transfer at the coolant side limits both efficiency and performance density of the apparatus. Here, due to restrictions in construction and design, backwater areas and stagnation regions cannot be avoided. Those unwanted changes in flow characteristics are mainly triggered by flow deflections and sudden cross-sectional expansions. In application, mixtures of water and glysantine are used as appropriate coolants. Such coolants typically show an electrical conductivity of a few S/m. Coolant flow and convective heat transfer can then be controlled using Lorentz forces. These body forces are generated within the conducting fluid by the interactions of an electrical current density and a localized magnetic field, both of which are externally superimposed. In future application, this could be achieved by inserting electrodes in the cooler wall and a corresponding arrangement of permanent magnets. In this paper we perform numerical simulations of such magnetohydrodynamic flow in three model geometries that frequently appear in engine cooling applications: Carnot-Borda diffusor, 90° bend, and 180° bend. The simulations are carried out using the software package ANSYS Fluent. The present study demonstrates that, depending on the electromagnetic interaction parameter and the specific geometric arrangement of electrodes and magnetic field, Lorentz forces are suitable to break up eddy waters and separation zones and thus significantly increase convective heat transfer in these areas. Furthermore, the results show that hydraulic pressure losses can be reduced due to the pumping action of the Lorentz forces.

  13. Extremely low frequency electromagnetic fields and cancer: the epidemiologic evidence.

    PubMed Central

    Bates, M N

    1991-01-01

    This paper reviews the epidemiologic evidence that low frequency electromagnetic fields generated by alternating current may be a cause of cancer. Studies examining residential exposures of children and adults and studies of electrical and electronics workers are reviewed. Using conventional epidemiologic criteria for inferring causal associations, including strength and consistency of the relationship, biological plausibility, and the possibility of bias as an explanation, it is concluded that the evidence is strongly suggestive that such radiation is carcinogenic. The evidence is strongest for brain and central nervous system cancers in electrical workers and children. Weaker evidence supports an association with leukemia in electrical workers. Some evidence also exists for an association with melanoma in electrical workers. Failure to find consistent evidence of a link between residential exposures and adult cancers may be attributable to exposure misclassification. Studies so far have used imperfect surrogates for any true biologically effective magnetic field exposure. The resulting exposure misclassification has produced relative risk estimates that understate any true risk. PMID:1821368

  14. Enhancement of osteogenic differentiation of rat adipose tissue-derived mesenchymal stem cells by zinc sulphate under electromagnetic field via the PKA, ERK1/2 and Wnt/β-catenin signaling pathways

    PubMed Central

    Fathi, Ezzatollah; Farahzadi, Raheleh

    2017-01-01

    Zinc ion as an essential trace element and electromagnetic fields (EMFs) has been reported to be involved in the regulation of bone metabolism. The aim of this study was to elucidate the effects of zinc sulphate (ZnSO4) on the osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) in the presence of EMF as a strategy in osteoporosis therapy. Alkaline phophatase (ALP) activity measurement, calcium assay and expression of several osteoblastic marker genes were examined to assess the effect of ZnSO4 on the osteogenic differentiation of ADSCs under EMF. The expression of cAMP and PKA was evaluated by ELISA. The expression of β-catenin, Wnt1, Wnt3a, low-density lipoprotein receptor-related protein 5 (LRP5) and reduced dickkopf1 (DKK1) genes were used to detect the Wnt/β-catenin pathway. It was found that ZnSO4, in the presence of EMF, resulted in an increase in the expression of osteogenic genes, ALP activity and calcium levels. EMF, in the presence of ZnSO4, increased the cAMP level and protein kinase A (PKA) activity. Treatment of ADSCs with (MAPK)/ERK kinase 1/2 inhibitor, or PKA inhibitor, significantly inhibited the promotion of osteogenic markers, indicating that the induction of osteogenesis was dependent on the ERK and PKA signaling pathways. Real-time PCR analysis showed that ZnSO4, in the presence of EMF, increased the mRNA expressions of β-catenin, Wnt1, Wnt3a, LRP5 and DKK1. In this study, it was shown that 0.432 μg/ml ZnSO4, in the presence of 50 Hz, 20 mT EMF, induced the osteogenic differentiation of ADSCs via PKA, ERK1/2 and Wnt/β-catenin signaling pathways. PMID:28339498

  15. Enhancement of osteogenic differentiation of rat adipose tissue-derived mesenchymal stem cells by zinc sulphate under electromagnetic field via the PKA, ERK1/2 and Wnt/β-catenin signaling pathways.

    PubMed

    Fathi, Ezzatollah; Farahzadi, Raheleh

    2017-01-01

    Zinc ion as an essential trace element and electromagnetic fields (EMFs) has been reported to be involved in the regulation of bone metabolism. The aim of this study was to elucidate the effects of zinc sulphate (ZnSO4) on the osteogenic differentiation of adipose tissue-derived mesenchymal stem cells (ADSCs) in the presence of EMF as a strategy in osteoporosis therapy. Alkaline phophatase (ALP) activity measurement, calcium assay and expression of several osteoblastic marker genes were examined to assess the effect of ZnSO4 on the osteogenic differentiation of ADSCs under EMF. The expression of cAMP and PKA was evaluated by ELISA. The expression of β-catenin, Wnt1, Wnt3a, low-density lipoprotein receptor-related protein 5 (LRP5) and reduced dickkopf1 (DKK1) genes were used to detect the Wnt/β-catenin pathway. It was found that ZnSO4, in the presence of EMF, resulted in an increase in the expression of osteogenic genes, ALP activity and calcium levels. EMF, in the presence of ZnSO4, increased the cAMP level and protein kinase A (PKA) activity. Treatment of ADSCs with (MAPK)/ERK kinase 1/2 inhibitor, or PKA inhibitor, significantly inhibited the promotion of osteogenic markers, indicating that the induction of osteogenesis was dependent on the ERK and PKA signaling pathways. Real-time PCR analysis showed that ZnSO4, in the presence of EMF, increased the mRNA expressions of β-catenin, Wnt1, Wnt3a, LRP5 and DKK1. In this study, it was shown that 0.432 μg/ml ZnSO4, in the presence of 50 Hz, 20 mT EMF, induced the osteogenic differentiation of ADSCs via PKA, ERK1/2 and Wnt/β-catenin signaling pathways.

  16. Growth inhibition of Staphylococcus aureus induced by low-frequency electric and electromagnetic fields.

    PubMed

    Obermeier, Andreas; Matl, Florian Dominik; Friess, Wolfgang; Stemberger, Axel

    2009-05-01

    Magnetic field therapy is an established technique in the treatment of pseudarthrosis. In cases of osteomylitis, palliation is also observed. This study focuses on the impact of different electric and electromagnetic fields on the growth of Staphylococcus aureus by in vitro technologies. Cultures of Staphylococcus aureus in fluid and gel-like medium were exposed to a low-frequency electromagnetic field, an electromagnetic field combined with an additional electric field, a sinusoidal electric field and a static electric field. In gel-like medium no significant difference between colony-forming units of exposed samples and non-exposed references was detected. In contrast, Staphylococcus aureus concentrations in fluid medium could clearly be reduced under the influence of the four different applied fields within 24 h of experiment. The strongest effects were observed for the direct current electric field which could decrease CFU/ml of 37%, and the low-frequency electromagnetic field with additional induced electric alternating field with a decrease of Staphylococci concentration by 36%. The effects of the electromagnetic treatment on Staphylococci within fluid medium are significantly higher than in gel-like medium. The application of low-frequency electromagnetic fields corroborates clinical situations of bone infections during magnetic field therapy. Copyright 2009 Wiley-Liss, Inc.

  17. Influence of strong field vacuum polarization on gravitational-electromagnetic wave interaction

    SciTech Connect

    Forsberg, M.; Brodin, G.; Papadopoulos, D.

    2010-07-15

    The interaction between gravitational and electromagnetic waves in the presence of a static magnetic field is studied. The field strength of the static field is allowed to surpass the Schwinger critical field, such that the QED effects of vacuum polarization and magnetization are significant. Equations governing the interaction are derived and analyzed. It turns out that the energy conversion from gravitational to electromagnetic waves can be significantly altered due to the QED effects. The consequences of our results are discussed.

  18. Electromagnetic Near-Field Computations for a Broadcast Monopole Using Numerical Electromagnetics Code (NEC).

    DTIC Science & Technology

    1983-09-01

    Electromagnetic Near-FEjeid Computazions for a Broadcast Mono~ole using ’Vimerical El.ectromagnetics Code (NEC) by David Duerr T-homson Li’~enntCommander... Poggio of Lawrence Livermore Laboratory, January 1981. 3. Schelkuncff, S.A. and Friis, H.T., Antennas Theory -and ?ractice, Wiley, 1952. 4. Jordan...Virginia 22314 2. Library, Code 0142 2 Naval Postgraduate School Monterey, California 93943 3. LCDR David D. Thomson (Code 33n9)2Naval Weapons Center

  19. Electromagnetic Radiation System (EMRS) for Susceptibility Testing.

    DTIC Science & Technology

    ELECTROMAGNETIC COMPATIBILITY, *ELECTROMAGNETIC SUSCEPTIBILITY, COMMUNICATION EQUIPMENT, ELECTRONIC EQUIPMENT, ELECTROMAGNETIC RADIATION , ANTENNAS, ELECTROMAGNETIC INTERFERENCE, RADAR SIGNALS, RADIO SIGNALS, FIELD INTENSITY.

  20. Possibility of sounding Earth by using electromagnetic field of sea current

    NASA Astrophysics Data System (ADS)

    Smagin, V. P.; Fonarev, G. A.; Savchenko, V. N.

    1985-06-01

    The possibilities of determining the conductivity of bottom rocks by measuring different combinations of components of the electromagnetic field of a current on the ocean floor are analyzed. It is shown that the sea current induces an electromagnetic field in the geomagnetic field. Then a formula is derived for the magnetic component B. After determining B it is possible to find the electric field in sea water and in rocks beneath the ocean layer. The parameter epsilon is introduced which makes it possible to ascertain the vertical gradient of the magnetic field in bottom rocks; a function is derived which characterizes the magnetic field in the bottom rocks. Formulas are derived which can be used in estimating the width of a current by an electromagnetic method. It is shown, therefore, that with electromagnetic sounding in the fields of sea currents it is possible to make a simple interpretation of the experimental data within the framework of an exponential model of ocean floor conductivity.

  1. [ASSESSMENT OF OCCUPATIONAL EXPOSURE TO RADIO FREQUENCY ELECTROMAGNETIC FIELDS].

    PubMed

    Aniołczyk, Halina; Mariańska, Magda; Mamrot, Paweł

    2015-01-01

    European Union Directive 2013/35/UE provides for the implementation of EU regulations into national legislation. Our aim is to assess actual health hazards from radiofrequency eldctromagnetic field (RF EMF) (range: 100 kHz - 300 GHz) and indicate workplaces with the highest risk to employee health. Data from measurements of RF EMF performed by the Laboratory of Electromagnetic Hazards in Nofer Institute of Occupational Medicine (Łódź, Poland) were analyzed. The analysis covered the results of electric field intensity (E) for over 450 selected items. The ranges of protection zones and the extent to which maximum admissible intensity (MAI) values were also analyzed. The determinations and'measurements of EMF in the work environment met the requirements of Polish Standard, while Polish regulations on the MAI values were used as the criterion for the assessment of the exposure. The highest values of E field intensity at workplaces were measured for: electrosurgery, to 400 V/m, and short-wave diathermy units, to 220 V/m, dielectric welders to 240 V/m, within the FM radio antenna systems, to 180 V/m. The widest protection zones were noted for prototype research instruments, short-wave diathermy units, and dielectric welders. The most excessive (up to 12-fold MAI) values were recorded for dielectric welders, short-wave diathermy units (up to 11-fold) and microwave diathermy units (up to 8-fold). Our results have confirmed the high RF EMF values for physiotherapists, operators of dielectric welders, and mast maintenance workers in radio com munication facilities (especially radio and TV broadcasting stations).

  2. Consequences of rotating off-centred dipolar electromagnetic field in vacuum around Pulsars

    NASA Astrophysics Data System (ADS)

    Kundu, A.; Pétri, J.

    2016-12-01

    Studying the electromagnetic field of pulsars is one of the key themes in neutron star physics. While most of the works assume a standard central dipolar electromagnetic field model, recently some efforts had been made in explaining how inclusion of higher field components produces drastic consequences in our understanding of these objects. We put forward the effects of a unique recently presented approach in which the magnetic axis is shifted off from the centre. It is found that the rotating off-centred dipolar electromagnetic field itself reveals the presence of the higher components within. The consequences of this approach on the shape of the polar caps and the emission diagrams are discussed.

  3. Effects of pulsed electromagnetic field frequencies on the osteogenic differentiation of human mesenchymal stem cells.

    PubMed

    Luo, Fei; Hou, Tianyong; Zhang, Zehua; Xie, Zhao; Wu, Xuehui; Xu, Jianzhong

    2012-04-01

    The purpose of this study was to evaluate the effect of different frequencies of pulsed electromagnetic fields on the osteogenic differentiation of human mesenchymal stem cells. Third-generation human mesenchymal stem cells were irradiated with different frequencies of pulsed electromagnetic fields, including 5, 25, 50, 75, 100, and 150 Hz, with a field intensity of 1.1 mT, for 30 minutes per day for 21 days. Changes in human mesenchymal stem cell morphology were observed using phase contrast microscopy. Alkaline phosphatase activity and osteocalcin expression were also determined to evaluate human mesenchymal stem cell osteogenic differentiation.Different effects were observed on human mesenchymal stem cell osteoblast induction following exposure to different pulsed electromagnetic field frequencies. Levels of human mesenchymal stem cell differentiation increased when the pulsed electromagnetic field frequency was increased from 5 hz to 50 hz, but the effect was weaker when the pulsed electromagnetic field frequency was increased from 50 Hz to 150 hz. The most significant effect on human mesenchymal stem cell differentiation was observed at of 50 hz.The results of the current study show that pulsed electromagnetic field frequency is an important factor with regard to the induction of human mesenchymal stem cell differentiation. Furthermore, a pulsed electromagnetic field frequency of 50 Hz was the most effective at inducing human mesenchymal stem cell osteoblast differentiation in vitro.

  4. Estimation of the Lithospheric Component Share in the Earth Natural Pulsed Electromagnetic Field Structure

    NASA Astrophysics Data System (ADS)

    Malyshkov, S. Y.; Gordeev, V. F.; Polyvach, V. I.; Shtalin, S. G.; Pustovalov, K. N.

    2017-04-01

    Article describes the results of the atmosphere and Earth’s crust climatic and ecological parameters integrated monitoring. The estimation is made for lithospheric component share in the Earth natural pulsed electromagnetic field structure. To estimate lithospheric component we performed a round-the-clock monitoring of the Earth natural pulsed electromagnetic field background variations at the experiment location and measured the Earth natural pulsed electromagnetic field under electric shields. Natural materials in a natural environment were used for shielding, specifically lakes with varying parameters of water conductivity. Skin effect was used in the experiment - it is the tendency of electromagnetic waves amplitude to decrease with greater depths in the conductor. Atmospheric and lithospheric component the Earth natural pulsed electromagnetic field data recorded on terrain was compared against the recorded data with atmosphere component decayed by an electric shield. In summary we have demonstrated in the experiment that thunderstorm discharge originating electromagnetic field decay corresponds to the decay calculated using Maxwell equations. In the absence of close lightning strikes the ratio of field intensity recorded on terrain to shielded field intensity is inconsistent with the ratio calculated for atmospheric sources, that confirms there is a lithospheric component present to the Earth natural pulsed electromagnetic field.

  5. Stimulation of experimental endochondral ossification by low-energy pulsing electromagnetic fields

    SciTech Connect

    Aaron, R.K.; Ciombor, D.M.; Jolly, G.

    1989-04-01

    Pulsed electromagnetic fields (PEMFs) of certain configuration have been shown to be effective clinically in promoting the healing of fracture nonunions and are believed to enhance calcification of extracellular matrix. In vitro studies have suggested that PEMFs may also have the effect of modifying the extracellular matrix by promoting the synthesis of matrix molecules. This study examines the effect of one PEMF upon the extracellular matrix and calcification of endochondral ossification in vivo. The synthesis of cartilage molecules is enhanced by PEMF, and subsequent endochondral calcification is stimulated. Histomorphometric studies indicate that the maturation of bone trabeculae is also promoted by PEMF stimulation. These results indicate that a specific PEMF can change the composition of cartilage extracellular matrix in vivo and raises the possibility that the effects on other processes of endochondral ossification (e.g., fracture healing and growth plates) may occur through a similar mechanism.

  6. Electromagnetic fields in neonatal incubators: the reasons for an alert.

    PubMed

    Bellieni, Carlo Valerio; Nardi, Valentina; Buonocore, Giuseppe; Di Fabio, Sandra; Pinto, Iole; Verrotti, Alberto

    2017-10-08

    Neonatal incubators are important tools for sick newborns in the first few days of life. Nevertheless, their electric engine, often very close to the newborn's body, emits electromagnetic fields (EMF) to which newborns are exposed. Aim of this paper is to review the available literature on EMF exposure in incubators, and the effects of such exposures on newborns that have been investigated. We carried out a systematic review of studies about EMF emissions produced by incubators, using Medline and Embase databases from 1993 to 2017. We retrieved 15 papers that described the EMF exposure in incubators and their biological effects on babies. EMF levels in incubators appear to be between 2 and 100 mG, depending on the distance of the mattress from the electric engine. In some cases they exceed this range. These values interfere with melatonin production or with vagal tone. Even caregivers are exposed to high EMF, above 200 mG, when working at close contact with the incubators. EMF have been described as potentially hazardous for human health, and values reported in this review are an alert to prevent babies' and caregivers' exposure when close to the incubators. A precautionary approach should be adopted in future incubator design, to prevent high exposures of newborns in incubators and of caregivers as well.

  7. The role of electromagnetic fields in neurological disorders.

    PubMed

    Terzi, Murat; Ozberk, Berra; Deniz, Omur Gulsum; Kaplan, Suleyman

    2016-09-01

    In the modern world, people are exposed to electromagnetic fields (EMFs) as part of their daily lives; the important question is "What is the effect of EMFs on human health?" Most previous studies are epidemiological, and we still do not have concrete evidence of EMF pathophysiology. Several factors may lead to chemical, morphological, and electrical alterations in the nervous system in a direct or indirect way. It is reported that non-ionizing EMFs have effects on animals and cells. The changes they bring about in organic systems may cause oxidative stress, which is essential for the neurophysiological process; it is associated with increased oxidization in species, or a reduction in antioxidant defense systems. Severe oxidative stress can cause imbalances in reactive oxygen species, which may trigger neurodegeneration. This review aims to detail these changes. Special attention is paid to the current data regarding EMFs' effects on neurological disease and associated symptoms, such as headache, sleep disturbances, and fatigue. Copyright © 2016 Elsevier B.V. All rights reserved.

  8. Effect of cyclophosphamide and electromagnetic fields on mouse bone marrow

    SciTech Connect

    Cadossi, R.; Zucchini, P.; Emilia, G.; Torelli, G. )

    1990-02-26

    The authors have previously shown that the exposure to low frequency pulsing electromagnetic fields (PEMF) of mice X-ray irradiated resulted in an increased damage to the bone marrow. The series of experiments here reported were designed to investigate the effect of PEMF exposure after intraperitoneum injection of 200mg/kg of cyclophosphamide (CY). Control mice were CY injected only; experimental mice were CY injected and then exposed to PEMF. Exposure to PEMF (24 hours/day) increased the rate of decline of white blood cells in peripheral blood. Spleen weight was statistically higher among control mice than among mice exposed to PEMF at day 6, 8 and 10 after CY injection. Spleen autoradiography proved to be higher among PEMF exposed mice than among controls at day 8 and 9 after CY injection. The grafting efficiency of the bone marrow obtained from control mice was higher than the grafting efficiency of the bone marrow recovered from mice exposed to PEMF. All these data indicate that the exposure to PEMF increases the cytotoxic effect of CY.

  9. Effect of electromagnetic field exposure on the reproductive system

    PubMed Central

    Park, Chan Jin

    2012-01-01

    The safety of human exposure to an ever-increasing number and diversity of electromagnetic field (EMF) sources both at work and at home has become a public health issue. To date, many in vivo and in vitro studies have revealed that EMF exposure can alter cellular homeostasis, endocrine function, reproductive function, and fetal development in animal systems. Reproductive parameters reported to be altered by EMF exposure include male germ cell death, the estrous cycle, reproductive endocrine hormones, reproductive organ weights, sperm motility, early embryonic development, and pregnancy success. At the cellular level, an increase in free radicals and [Ca2+]i may mediate the effect of EMFs and lead to cell growth inhibition, protein misfolding, and DNA breaks. The effect of EMF exposure on reproductive function differs according to frequency and wave, strength (energy), and duration of exposure. In the present review, the effects of EMFs on reproductive function are summarized according to the types of EMF, wave type, strength, and duration of exposure at cellular and organism levels. PMID:22563544

  10. Effect of extremely low frequency electromagnetic fields on bacterial membrane.

    PubMed

    Oncul, Sule; Cuce, Esra M; Aksu, Burak; Inhan Garip, Ayse

    2016-01-01

    The effect of extremely low frequency electromagnetic fields (ELF-EMF) on bacteria has attracted attention due to its potential for beneficial uses. This research aimed to determine the effect of ELF-EMF on bacterial membrane namely the membrane potential, surface potential, hydrophobicity, respiratory activity and growth. Gram-positive Staphylococcus aureus and Gram-negative Escherichia coli were subjected to ELF-EMF, 50 Hz, 1 mT for 2 h. Membrane potential was determined by fluorescence spectroscopy with or without EDTA (Ethylenediaminetetraacetic acid) with DisC3(5) (3,3-dipropylthiacarbocyanine iodide), zeta potential measurements were performed by electrophoretic mobility, hydrophobicity of the membrane was measured with MATH (Microbial Adhesion to Hydrocarbons) test, respiratory activity was determined with CTC (5-Cyano-2,3-ditolyl tetrazolium chloride), colony forming unit (CFU) and DAPI (4',6-diamidino-2-phenylindole, dihydrochloride) was used for growth determinations. ELF-EMF caused changes in physicochemical properties of both Gram-positive and Gram-negative bacteria. Hyperpolarization was seen in S. aureus and EDTA-treated E. coli. Surface potential showed a positive shift in S. aureus contrariwise to the negative shift seen in EDTA-untreated E. coli. Respiratory activity increased in both bacteria. A slight decrease in growth was observed. These results show that ELF-EMF affects the crucial physicochemical processes in both Gram-positive and Gram-negative bacteria which need further research.

  11. Effects of Electromagnetic Fields on Automated Blood Cell Measurements.

    PubMed

    Vagdatli, Eleni; Konstandinidou, Vasiliki; Adrianakis, Nikolaos; Tsikopoulos, Ioannis; Tsikopoulos, Alexios; Mitsopoulou, Kyriaki

    2014-08-01

    The aim of this study is to investigate whether the electromagnetic fields associated with mobile phones and/or laptops interfere with blood cell counts of hematology analyzers. Random blood samples were analyzed on an Aperture Impedance hematology analyzer. The analysis was performed in four ways: (A) without the presence of any mobile phone or portable computer in use, (B) with mobile phones in use (B1: one mobile, B4: four mobiles), (C) with portable computers (laptops) in use (C1: one laptop, C3: three laptops), and (D) with four mobile phones and three laptops in use simultaneously. The results obtained demonstrated a statistically significant decrease in neutrophil, erythrocyte, and platelet count and an increase in lymphocyte count, mean corpuscular volume, and red blood cell distribution width, notably in the B4 group. Despite this statistical significance, in clinical practice, only the red blood cell reduction could be taken into account, as the mean difference between the A and B4 group was 60,000 cells/µL. In group D, the analyzer gave odd results after 11 measurements and finally stopped working. The combined and multiple use of mobile phones and computers affects the function of hematology analyzers, leading to false results. Consequently, the use of such electronic devices must be avoided.

  12. Influence of different types of electromagnetic fields on skin reparatory processes in experimental animals.

    PubMed

    Matic, Milan; Lazetic, Bogosav; Poljacki, Mirjana; Djuran, Verica; Matic, Aleksandra; Gajinov, Zorica

    2009-05-01

    Wound healing is a very complex process, some phases of which have only recently been explained. Magnetic and electromagnetic fields can modulate this process in a non-thermal way. The aim of this research was to compare the influence of constant and pulsed electromagnetic fields and low-level laser therapy (LLLT) on wound healing in experimental animals. The experiment was conducted on 120 laboratory rats divided into four groups of 30 animals each (constant electromagnetic field, pulsed electromagnetic field, LLLT and control group). It lasted for 21 days. Under the influence of the constant electromagnetic field the healing of the skin defect was accelerated in comparison with the control group. The difference was statistically significant in all the weeks of the experiment at the P < 0.01 level. Accelerated healing was also observed under the influence of the pulsed electromagnetic field (P < 0.05). In the group of animals exposed to LLLT, the healing of the skin defect was faster than in the control group. The statistical significance was at the P < 0.05 level. Different types of electromagnetic fields have a promoting effect on the wound healing process.

  13. Pulsed electromagnetic field with or without exercise therapy in the treatment of benign prostatic hyperplasia.

    PubMed

    Elgohary, Hany M; Tantawy, Sayed A

    2017-08-01

    [Purpose] To investigate the effect of pulsed electromagnetic field with or without exercise therapy in the treatment of benign prostatic hyperplasia. [Subjects and Methods] Sixty male patients aged 55-65 years with benign prostatic hyperplasia were invited to participate in this study. Patients were randomly assigned to Group A (n=20; patients who received pulsed electromagnetic field in addition to pelvic floor and aerobic exercises), Group B (n=20; patients who received pulsed electromagnetic field), and Group C (n=20; patients who received placebo electromagnetic field). The assessments included post-void residual urine, urine flow rate, prostate specific antigen, white blood cells count, and International Prostate Symptom Score were weighed, before and after a 4-week intervention. [Results] There were significant differences in Group A and B in all parameters. Group C showed non-significant differences in all measured variables except for International Prostate Symptom Score. Among groups, all parameters showed highly significant differences in favor of Group A. There were non-significant differences between Group A and B and significant difference between Groups A and C and between Groups B and C. [Conclusion] The present study demonstrated that electromagnetic field had a significant impact on the treatment of benign prostatic hyperplasia. Accordingly, electromagnetic field can be utilized alone or in combination with other physiotherapy modalities. Moreover, clinicians should have the capacity to perceive the advantages accomplished using extra treatment alternatives. Electromagnetic field is a safe, noninvasive method and can be used for the treatment of benign prostatic hyperplasia.

  14. Occupational exposure to electromagnetic fields and acute leukaemia: analysis of a case-control study

    PubMed Central

    Willett, E; McKinney, P; Fear, N; Cartwright, R; Roman, E

    2003-01-01

    Aims: To investigate whether the risk of acute leukaemia among adults is associated with occupational exposure to electromagnetic fields. Methods: Probable occupational exposure to electromagnetic fields at higher than typical residential levels was investigated among 764 patients diagnosed with acute leukaemia during 1991–96 and 1510 sex and age matched controls. A job exposure matrix was applied to the self reported employment histories to determine whether or not a subject was exposed to electromagnetic fields. Risks were assessed using conditional logistic regression for a matched analysis. Results: Study subjects considered probably ever exposed to electromagnetic fields at work were not at increased risk of acute leukaemia compared to those considered never exposed. Generally, no associations were observed on stratification by sex, leukaemia subtype, number of years since exposure stopped, or occupation; there was no evidence of a dose-response effect using increasing number of years exposed. However, relative to women considered never exposed, a significant excess of acute lymphoblastic leukaemia was observed among women probably exposed to electromagnetic fields at work that remained increased irrespective of time prior to diagnosis or job ever held. Conclusion: This large population based case-control study found little evidence to support an association between occupational exposure to electromagnetic fields and acute leukaemia. While an excess of acute lymphoblastic leukaemia among women was observed, it is unlikely that occupational exposure to electromagnetic fields was responsible, given that increased risks remained during periods when exposure above background levels was improbable. PMID:12883018

  15. New model for high-power electromagnetic field instability in transparent media

    NASA Astrophysics Data System (ADS)

    Gruzdev, Vitali E.

    1997-05-01

    A model of high-power field instability is developed to describe local abrupt increasing of electromagnetic field intensity in transparent dielectric. Small local enhancement of the field amplitude is initiated by low-absorbing spherical inclusion which size is less than radiation wavelength. Exceeding threshold of optical bistability results in abrupt increasing of field amplitude in the defect that also leads to local increasing of field amplitude in the host material in the vicinity of the inclusion. Bearing in mind nonlinear dependence of refractive index of the host material on light intensity we develop a model to describe 'spreading' of initial defect up to size appropriate for the first resonant field mode to be formed. Increasing of refraction index due to nonlinear light-matter interaction and existence of high-Q eigenmodes of dielectric sphere can both cause positive feedback's and result in field instability in the medium. Estimates are obtained of the threshold value of incident-field amplitude. This model is applied to analysis of some experimental data on optical breakdown of transparent dielectrics and thin films, both impurity-induced and intrinsic. The model can also be used to consider bulk optical breakdown by tightly focused light beams.

  16. Exposure to electromagnetic fields from laptop use of "laptop" computers.

    PubMed

    Bellieni, C V; Pinto, I; Bogi, A; Zoppetti, N; Andreuccetti, D; Buonocore, G

    2012-01-01

    Portable computers are often used at tight contact with the body and therefore are called "laptop." The authors measured electromagnetic fields (EMFs) laptop computers produce and estimated the induced currents in the body, to assess the safety of laptop computers. The authors evaluated 5 commonly used laptop of different brands. They measured EMF exposure produced and, using validated computerized models, the authors exploited the data of one of the laptop computers (LTCs) to estimate the magnetic flux exposure of the user and of the fetus in the womb, when the laptop is used at close contact with the woman's womb. In the LTCs analyzed, EMF values (range 1.8-6 μT) are within International Commission on Non-Ionizing Radiation (NIR) Protection (ICNIRP) guidelines, but are considerably higher than the values recommended by 2 recent guidelines for computer monitors magnetic field emissions, MPR II (Swedish Board for Technical Accreditation) and TCO (Swedish Confederation of Professional Employees), and those considered risky for tumor development. When close to the body, the laptop induces currents that are within 34.2% to 49.8% ICNIRP recommendations, but not negligible, to the adult's body and to the fetus (in pregnant women). On the contrary, the power supply induces strong intracorporal electric current densities in the fetus and in the adult subject, which are respectively 182-263% and 71-483% higher than ICNIRP 98 basic restriction recommended to prevent adverse health effects. Laptop is paradoxically an improper site for the use of a LTC, which consequently should be renamed to not induce customers towards an improper use.

  17. The regenerative effects of electromagnetic field on spinal cord injury.

    PubMed

    Ross, Christina L; Syed, Ishaq; Smith, Thomas L; Harrison, Benjamin S

    2017-01-01

    Traumatic spinal cord injury (SCI) is typically the result of direct mechanical impact to the spine, leading to fracture and/or dislocation of the vertebrae along with damage to the surrounding soft tissues. Injury to the spinal cord results in disruption of axonal transmission of signals. This primary trauma causes secondary injuries that produce immunological responses such as neuroinflammation, which perpetuates neurodegeneration and cytotoxicity within the injured spinal cord. To date there is no FDA-approved pharmacological agent to prevent the development of secondary SCI and induce regenerative processes aimed at healing the spinal cord and restoring neurological function. An alternative method to electrically activate spinal circuits is the application of a noninvasive electromagnetic field (EMF) over intact vertebrae. The EMF method of modulating molecular signaling of inflammatory cells emitted in the extra-low frequency range of <100 Hz, and field strengths of <5 mT, has been reported to decrease inflammatory markers in macrophages, and increase endogenous mesenchymal stem cell (MSC) proliferation and differentiation rates. EMF has been reported to promote osteogenesis by improving the effects of osteogenic media, and increasing the proliferation of osteoblasts, while inhibiting osteoclast formation and increasing bone matrix in vitro. EMF has also been shown to increase chondrogenic markers and collagen and induce neural differentiation, while increasing cell viability by over 50%. As advances are made in stem cell technologies, stabilizing the cell line after differentiation is crucial to SCI repair. Once cell-seeded scaffolds are implanted, EMF may be applied outside the wound for potential continued adjunct treatment during recovery.

  18. Photon drag enhancement by a slow-light moving medium via electromagnetically-induced transparency amplification

    NASA Astrophysics Data System (ADS)

    Iqbal, Azmat; Khan, Naveed; Bacha, Bakht Amin; Rahman, Amin Ur; Ahmad, Afaq

    2017-09-01

    Recently, a considerable enhancement has been observed in the celebrated Fresnel-Fizeau light drag by innovative experimental and theoretical approaches because of its fundamental and practical interest in the emerging technology of quantum optics and photonics. We present a semiclassical density matrix approach on the demonstration of light drag in a slow-light moving medium comprising five-level single tripod atomic configuration. To accomplish this, we introduce Kerr-type nonlinearity that leads to electromagnetically-induced transparency amplification under resonance conditions. By switching ON Kerr-type nonlinearity effect, we observe a prominent transparency window in probe field's absorption spectrum whose width and amplitude can be controlled further by the intensity of Kerr field and control field. The incorporation of Kerr field also switches light propagation from superluminal to subluminal domain. We predict a significant enhancement both in the lateral and the rotary photon drag owing to drag of light linear polarization state subjected to translation and rotation of the host medium, respectively. Consistent with earlier results, light drag considerably depends on both transverse and angular velocity of the host medium. In regime of subluminal propagation, light polarization state drags along the medium motion while in the superluminal propagation region it drags opposite to the medium motion.

  19. Effects of Extremely Low Frequency Electromagnetic Fields on Growth and Differentiation of ’Physarum polycephalum’

    DTIC Science & Technology

    1975-04-01

    AD-AO10 187 EFFECTS OF EXTREMELY LOW FREQUENCY ELECTRO- MAGNETIC FIELDS ON GROWTH AND DIFFERENTIATION OF ’ PHYSARUM POLYCEPHALUM ’ E. M. Guodman, et al...LExtremely Low Prequency Electromagnetic Fields on Growth and Differentiation of Physarum polycephalum Technical Report Phase I (Continuous Wave) by...that weak, alternating electromagnetic fields (60 or 75 Hz, 2.0 G, 0.7 V/n) affect the cell cycle of Physarum polycephalum by increasing the interval

  20. Spatial dependence of electromagnetic ion cyclotron waves triggered by solar wind dynamic pressure enhancements

    NASA Astrophysics Data System (ADS)

    Cho, J.-H.; Lee, D.-Y.; Noh, S.-J.; Kim, H.; Choi, C. R.; Lee, J.; Hwang, J.

    2017-05-01

    In this paper, using the multisatellite (the Van Allen Probes and two GOES satellites) observations in the inner magnetosphere, we examine two electromagnetic ion cyclotron (EMIC) wave events that are triggered by Pdyn enhancements under prolonged northward interplanetary magnetic field quiet time preconditions. For both events, the impact of enhanced Pdyn causes EMIC waves at multiple points. However, we find a strong spatial dependence that EMIC waves due to enhanced Pdyn impact can occur at multiple points (likely globally but not necessarily everywhere) but with different wave properties. For Event 1, three satellites situated at a nearly same dawnside zone but at slightly different L shells see occurrence of EMIC waves but in different frequencies relative to local ion gyrofrequencies and with different polarizations. These waves are found inside or at the outer edge of the plasmasphere. Another satellite near noon observes no dramatic EMIC wave despite the strongest magnetic compression there. For Event 2, the four satellites are situated at widely separated magnetic local time zones when they see occurrence of EMIC waves. They are again found at different frequencies relative to local ion gyrofrequencies with different polarizations and all outside the plasmasphere. We propose two possible explanations that (i) if triggered by enhanced Pdyn impact, details of ion cyclotron instability growth can be sensitive to local plasma conditions related to background proton distributions, and (ii) there can be preexisting waves with a specific spatial distribution, which determines occurrence and specific properties of EMIC waves depending on satellite's relative position after an enhanced Pdyn arrives.

  1. Idiopathic Environmental Intolerance Attributed to Electromagnetic Fields: A Content Analysis of British Newspaper Reports

    PubMed Central

    Eldridge-Thomas, Buffy; Rubin, G James

    2013-01-01

    Idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) is a controversial condition in which people describe symptoms following exposure to electromagnetic fields from everyday electrical devices. However, double-blind experiments have found no convincing evidence that electromagnetic fields cause these symptoms. In this study, we assessed whether recent newspaper reporting in the UK reflected this scientific evidence. We searched a database of newspaper articles to identify all those that contained IEI-EMF related keywords and selected a random sample of 60 for content analysis. For our primary outcomes, we assessed how many articles mainly or wholly presented an electromagnetic cause for IEI-EMF and how many discussed unproven treatments for the condition such as strategies intended to reduce exposure to electromagnetic fields or the use of complementary and alternative therapies. We also assessed whether the type of information source used by a newspaper article (e.g. scientist, person with IEI-EMF, politician) or the type of newspaper (broadsheet, tabloid, local or regional) was associated with either outcome. Of the 60 articles, 43 (71.7%) presented a mainly electromagnetic cause, compared to 13 (21.7%) which presented mainly non-electromagnetic causes and 4 (6.7%) which did not discuss a cause. 29 (48.3%) did not mention any potential treatment, while 24 (40.0%) mentioned eletromagnetic field related strategies and 12 (20.0%) mentioned complementary or alternative therapies. Articles which quoted someone with IEI-EMF were significantly more likely to report an electromagnetic cause and to present unproven treatments. Those which used a scientist as a source were more likely to present a non-electromagnetic cause for the condition. The widespread poor reporting we identified is disappointing and has the potential for to encourage more people to misattribute their symptoms to electromagnetic fields. Scientists should remain engaged

  2. Idiopathic environmental intolerance attributed to electromagnetic fields: a content analysis of British newspaper reports.

    PubMed

    Eldridge-Thomas, Buffy; Rubin, G James

    2013-01-01

    Idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) is a controversial condition in which people describe symptoms following exposure to electromagnetic fields from everyday electrical devices. However, double-blind experiments have found no convincing evidence that electromagnetic fields cause these symptoms. In this study, we assessed whether recent newspaper reporting in the UK reflected this scientific evidence. We searched a database of newspaper articles to identify all those that contained IEI-EMF related keywords and selected a random sample of 60 for content analysis. For our primary outcomes, we assessed how many articles mainly or wholly presented an electromagnetic cause for IEI-EMF and how many discussed unproven treatments for the condition such as strategies intended to reduce exposure to electromagnetic fields or the use of complementary and alternative therapies. We also assessed whether the type of information source used by a newspaper article (e.g. scientist, person with IEI-EMF, politician) or the type of newspaper (broadsheet, tabloid, local or regional) was associated with either outcome. Of the 60 articles, 43 (71.7%) presented a mainly electromagnetic cause, compared to 13 (21.7%) which presented mainly non-electromagnetic causes and 4 (6.7%) which did not discuss a cause. 29 (48.3%) did not mention any potential treatment, while 24 (40.0%) mentioned eletromagnetic field related strategies and 12 (20.0%) mentioned complementary or alternative therapies. Articles which quoted someone with IEI-EMF were significantly more likely to report an electromagnetic cause and to present unproven treatments. Those which used a scientist as a source were more likely to present a non-electromagnetic cause for the condition. The widespread poor reporting we identified is disappointing and has the potential for to encourage more people to misattribute their symptoms to electromagnetic fields. Scientists should remain engaged

  3. Electromagnetically induced 2D grating via refractive index enhancement in a far-off resonant system

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Yuan; Liu, Zhuan-Zhuan; Wan, Ren-Gang

    2017-07-01

    We propose a scheme for electromagnetically induced 2D grating in a mixture of two three-level Λ systems driven by two pairs of far-detuned coherent standing-wave fields. The key idea, which has been used to achieve the refractive index enhancement with vanishing absorption, is to induce two Raman resonances for the probe field, and their strength can be tuned via the two-photon detunings and the intensity of coupling field. By manipulating the absorption and gain properties of these two Raman resonances, absorption-phase grating, phase grating and gain-phase grating which effectively diffract a probe field into high-order directions can be formed in the atoms with the help of standing-wave pattern coherent fields. The diffracting power of the presented gratings strongly depends on the two-photon resonance condition and amplitude of coherent fields, hence the gratings can be used as all-optical multi-channel splitters or all-optical router in optical networking and communication.

  4. Entanglement control in a superconducting qubit system by an electromagnetic field

    NASA Astrophysics Data System (ADS)

    Zhang, Y. Q.; Xu, J. B.

    2011-08-01

    By making use of the dynamical algebraic method we investigate a quantum system consisting of superconducting qubits interacting with data buses, where the qubits are driven by time-dependent electromagnetic field and obtain an explicit expression of time evolution operator. Furthermore, we explore the entanglement dynamics and the influence of the time-dependent electromagnetic field and the initial state on the entanglement sudden death and birth for the system. It is shown that the entanglement between the qubit and bus as well as the entanglement sudden death and birth can be controlled by the time-dependent electromagnetic field.

  5. More on the covariant retarded Green's function for the electromagnetic field in de Sitter spacetime

    SciTech Connect

    Higuchi, Atsushi; Lee, Yen Cheong; Nicholas, Jack R.

    2009-11-15

    In a recent paper 2 it was shown in examples that the covariant retarded Green's functions in certain gauges for electromagnetism and linearized gravity can be used to reproduce field configurations correctly in spite of the spacelike nature of past infinity in de Sitter spacetime. In this paper we extend the work of Ref. 2 concerning the electromagnetic field and show that the covariant retarded Green's function with an arbitrary value of the gauge parameter reproduces the electromagnetic field from two opposite charges at antipodal points of de Sitter spacetime.

  6. Ultrastructural Study on Ultra-Low Frequency Electromagnetic Fields and Transfer Factor Effects on Skin Ulcers

    SciTech Connect

    Cadena, M. S. Reyes; Chapul, L. Sanchez; Perez, Javier; Garcia, M. N. Jimenez; Lopez, M. A. Jimenez; Espindola, M. E. Sanchez; Perez, R. Paniagua; Hernandez, N. A.; Paniagua, G.; Uribe, F.; Nava, J. J. Godina; Segura, M. A. Rodriguez

    2008-08-11

    We determined the effect of 120Hz ultra low frequency electromagnetic field (ELF) on the healing process of skin in 20 Wistar rats distributed in four groups in which chronic dermal ulcers had been produced. The first two groups received a dose of the transfer factor and interferon-beta (IFN-{beta}) every 24 h during 12 days. The third group (positive control) received only electromagnetic field (ELF) sessions, and in the fourth group (negative control), no treatment was applied. The electromagnetic field was applied through a Helmholtz coils; 30 Gauss of intensity. Results shown histological changes that improve the healing process in animals subjected to ELF together with the transfer factor.

  7. Dynamic model for electromagnetic field and heating patterns in loaded cylindrical cavities

    SciTech Connect

    Tian, Y.L.; Black, W.M.; Sa`adaldin, H.S.; Ahmad, I.; Silberglitt, R.

    1995-07-01

    An analytical solution for the electromagnetic fields in a cylindrical cavity, partially filled with a cylindrical dielectric has been recently reported. A program based on this solution has been developed and combined with the authors` previous program for heat transfer analysis. The new software has been used to simulate the dynamic temperature profiles of microwave heating and to investigate the role of electromagnetic field in heating uniformity and stability. The effects of cavity mode, cavity dimension, the dielectric properties of loads on electromagnetic field and heating patterns can be predicted using this software.

  8. Investigation of brain potentials in sleeping humans exposed to the electromagnetic field of mobile phones.

    PubMed

    Lebedeva, N N; Sulimov, A V; Sulimova, O P; Korotkovskaya, T I; Gailus, T

    2001-01-01

    An investigation was made of 8-hour EEG tracings of sleeping humans exposed to the electromagnetic field of a GSM-standard mobile phone. To analyze the EEG-patterns, manual scoring, nonlinear dynamics, and spectral analysis were employed. It was found that, when human beings were exposed to the electromagnetic field of a cellular phone, their cerebral cortex biopotentials revealed an increase in the alpha-range power density as compared to the placebo experiment. It was also found that the dimension of EEG correlation dynamics and the relation of sleep stages changed under the influence of the electromagnetic field of a mobile phone.

  9. Operator of pair electron-ion collisions in alternating electromagnetic fields

    SciTech Connect

    Balakin, A. A.

    2008-12-15

    Collisions of electrons with ions in the presence of an alternating electromagnetic field are considered. Based on the first principles (the Liouville equations for N particles), a general expression for the collisional operator in the approximation of pair collisions at an arbitrary scattering potential, including that depending periodically on time, is derived. The problem of collisions in plasma in the presence of an electromagnetic field can be reduced to this case by introducing drift coordinates. It is shown that the method of test particles can be applied to the problem of particle collisions in an alternating electromagnetic field.

  10. Impact of Low Frequency Electromagnetic Field Exposure on the Candida Albicans

    NASA Astrophysics Data System (ADS)

    Malíková, Ivona; Janoušek, Ladislav; Fantova, Vladyslava; Jíra, Jaroslav; Kříha, Vítĕzslav

    2015-03-01

    Effect of low frequency electromagnetic field on growth of selected microorganism is studied in the article. The diploid fungus that grows both as yeast and filamentous cell was chosen for this research. The theory of ion parametric resonance was taken as the base for studying the influence of electromagnetic field on biological structures. We tested the hypothesis, whether it is possible to observe the change in growth properties of Candida albicans with an AC electromagnetic field tuned to resonance with calcium ions cyclotron frequency.

  11. Ultrastructural Study on Ultra-Low Frequency Electromagnetic Fields and Transfer Factor Effects on Skin Ulcers

    NASA Astrophysics Data System (ADS)

    Cadena, M. S. Reyes; Chapul, L. Sánchez; Pérez, Javiér; García, M. N. Jiménez; López, M. A. Jiménez; Espíndola, M. E. Sánchez; Perez, R. Paniagua; Hernández, N. A.; Paniagua, G.; Uribe, F.; Nava, J. J. Godina; Segura, M. A. Rodríguez

    2008-08-01

    We determined the effect of 120Hz ultra low frequency electromagnetic field (ELF) on the healing process of skin in 20 Wistar rats distributed in four groups in which chronic dermal ulcers had been produced. The first two groups received a dose of the transfer factor and interferon-beta (IFN-β) every 24 h during 12 days. The third group (positive control) received only electromagnetic field (ELF) sessions, and in the fourth group (negative control), no treatment was applied. The electromagnetic field was applied through a Helmholtz coils; 30 Gauss of intensity. Results shown histological changes that improve the healing process in animals subjected to ELF together with the transfer factor.

  12. Genetic analysis of circadian responses to low frequency electromagnetic fields in Drosophila melanogaster.

    PubMed

    Fedele, Giorgio; Edwards, Mathew D; Bhutani, Supriya; Hares, John M; Murbach, Manuel; Green, Edward W; Dissel, Stephane; Hastings, Michael H; Rosato, Ezio; Kyriacou, Charalambos P

    2014-12-01

    The blue-light sensitive photoreceptor cryptochrome (CRY) may act as a magneto-receptor through formation of radical pairs involving a triad of tryptophans. Previous genetic analyses of behavioral responses of Drosophila to electromagnetic fields using conditioning, circadian and geotaxis assays have lent some support to the radical pair model (RPM). Here, we describe a new method that generates consistent and reliable circadian responses to electromagnetic fields that differ substantially from those already reported. We used the Schuderer apparatus to isolate Drosophila from local environmental variables, and observe extremely low frequency (3 to 50 Hz) field-induced changes in two locomotor phenotypes, circadian period and activity levels. These field-induced phenotypes are CRY- and blue-light dependent, and are correlated with enhanced CRY stability. Mutational analysis of the terminal tryptophan of the triad hypothesised to be indispensable to the electron transfer required by the RPM reveals that this residue is not necessary for field responses. We observe that deletion of the CRY C-terminus dramatically attenuates the EMF-induced period changes, whereas the N-terminus underlies the hyperactivity. Most strikingly, an isolated CRY C-terminus that does not encode the Tryptophan triad nor the FAD binding domain is nevertheless able to mediate a modest EMF-induced period change. Finally, we observe that hCRY2, but not hCRY1, transformants can detect EMFs, suggesting that hCRY2 is blue light-responsive. In contrast, when we examined circadian molecular cycles in wild-type mouse suprachiasmatic nuclei slices under blue light, there was no field effect. Our results are therefore not consistent with the classical Trp triad-mediated RPM and suggest that CRYs act as blue-light/EMF sensors depending on trans-acting factors that are present in particular cellular environments.

  13. Induction of tamoxifen resistance in breast cancer cells by ELF electromagnetic fields

    SciTech Connect

    Girgert, Rainer . E-mail: rainer.girgert@med.uni-goettingen.de; Schimming, Hartmut; Koerner, Wolfgang; Gruendker, Carsten; Hanf, Volker

    2005-11-04

    The incidence of breast cancer in western societies has been rising ever since the Second World War. Besides the exposure to a multitude of new chemical compounds, electromagnetic field exposure has been linked to breast cancer through a radiation-mediated anti-melatonin pathway. We investigated, whether low-frequency electromagnetic field exposure interferes with the anti-estrogenic activity of tamoxifen. Two different clones of the breast cancer cell line MCF-7 were exposed to highly homogeneous 50 Hz electromagnetic fields and IC{sub 50} values were calculated from dose-response curves of tamoxifen at various field intensities. An intensity-dependent shift of tamoxifen dose-response curves to higher concentrations with a maximal response at 1.2 {mu}T was observed. Hypothetically, electromagnetic field exposure could contribute to tamoxifen resistance observed in breast cancer after long-term treatment.

  14. Induction of tamoxifen resistance in breast cancer cells by ELF electromagnetic fields.

    PubMed

    Girgert, Rainer; Schimming, Hartmut; Körner, Wolfgang; Gründker, Carsten; Hanf, Volker

    2005-11-04

    The incidence of breast cancer in western societies has been rising ever since the Second World War. Besides the exposure to a multitude of new chemical compounds, electromagnetic field exposure has been linked to breast cancer through a radiation-mediated anti-melatonin pathway. We investigated, whether low-frequency electromagnetic field exposure interferes with the anti-estrogenic activity of tamoxifen. Two different clones of the breast cancer cell line MCF-7 were exposed to highly homogeneous 50Hz electromagnetic fields and IC(50) values were calculated from dose-response curves of tamoxifen at various field intensities. An intensity-dependent shift of tamoxifen dose-response curves to higher concentrations with a maximal response at 1.2muT was observed. Hypothetically, electromagnetic field exposure could contribute to tamoxifen resistance observed in breast cancer after long-term treatment.

  15. Optimizing electromagnetic levitation design to enhance thermodynamic measurement

    NASA Astrophysics Data System (ADS)

    Royer, Zachary L.

    Here we consider two studies which show how computer modeling and simulation can be used to study aspects of material science for which experimental methods would be time consuming or difficult. In the first we examined the optimization of electromagnetic levitation coils, for reduced sample temperature, through the development of a genetic algorithm and a rigorous analytical model. In the development of the analytical model for levitation, we propose a new model for the heating effect from a design consisting of a series of co-axial circular loops. With the new model we are better able to predict sample temperatures as compared with existing models. The new model is incorporated into a robust genetic algorithm to produce a powerful and generic design tool for the creation of levitation coils. Using this new design tool we seek to expand the range of temperatures (specifically to lower temperatures) and materials that are able to be studied using EML. In the second study, we examine the growth of a grain structure in the presence of second phase particles that act as pinning agents. The existing models of grain growth with pinning agents have thus far focused on particle distributions at the extremes of grain boundary correlation. When experimental measurements at the limits of correlation are compared to the appropriate models, they have shown good agreement but seem to suggest that there is a transition in behavior between the limits but the nature and mechanisms are not well known. As such we look to study pinning agent distributions centered around the initial grain boundaries and varied in such a way as to examine the transition from high to low boundary correlation. The results show that the average grain size varies smoothly during the transition. However, the results also show that there is an anomalous increase in grain size, when the boundary region containing pinning agents is slightly larger than the diffuse boundary width from the phase-field model and

  16. Statistical analysis of personal radiofrequency electromagnetic field measurements with nondetects.

    PubMed

    Röösli, Martin; Frei, Patrizia; Mohler, Evelyn; Braun-Fahrländer, Charlotte; Bürgi, Alfred; Fröhlich, Jürg; Neubauer, Georg; Theis, Gaston; Egger, Matthias

    2008-09-01

    Exposimeters are increasingly applied in bioelectromagnetic research to determine personal radiofrequency electromagnetic field (RF-EMF) exposure. The main advantages of exposimeter measurements are their convenient handling for study participants and the large amount of personal exposure data, which can be obtained for several RF-EMF sources. However, the large proportion of measurements below the detection limit is a challenge for data analysis. With the robust ROS (regression on order statistics) method, summary statistics can be calculated by fitting an assumed distribution to the observed data. We used a preliminary sample of 109 weekly exposimeter measurements from the QUALIFEX study to compare summary statistics computed by robust ROS with a naïve approach, where values below the detection limit were replaced by the value of the detection limit. For the total RF-EMF exposure, differences between the naïve approach and the robust ROS were moderate for the 90th percentile and the arithmetic mean. However, exposure contributions from minor RF-EMF sources were considerably overestimated with the naïve approach. This results in an underestimation of the exposure range in the population, which may bias the evaluation of potential exposure-response associations. We conclude from our analyses that summary statistics of exposimeter data calculated by robust ROS are more reliable and more informative than estimates based on a naïve approach. Nevertheless, estimates of source-specific medians or even lower percentiles depend on the assumed data distribution and should be considered with caution.

  17. Influence of exposure to electromagnetic field on the cardiovascular system.

    PubMed

    Jeong, J H; Kim, J S; Lee, B C; Min, Y S; Kim, D S; Ryu, J S; Soh, K S; Seo, K M; Sohn, U D

    2005-01-01

    1 We examined whether extremely low frequency electromagnetic fields (ELF-EMF) affect the basal level of cardiovascular parameters and influence of drugs acting on the sympathetic nervous system. 2 Male rats were exposed to sham control and EMF (60 Hz, 20 G) for 1 (MF-1) or 5 days (MF-5). We evaluated the alterations of blood pressure (BP), pulse pressure (PP), heart rate (HR), and the PR interval, QRS interval and QT interval on the electrocardiogram and dysrhythmic ratio in basal level and dysrhythmia induced by beta-adrenoceptor agonists. 3 In terms of the basal levels, there were no statistically significant differences among control, MF-1 and MF-5 in PR interval, QRS interval, mean BP, HR and PP. However, the QT interval, representing ventricular repolarization, was significantly reduced by MF-1 (P < 0.05). 4 (-)-Dobutamine (beta1-adrenoceptor-selective agonist)-induced tachycardia was significantly suppressed by ELF-EMF exposure in MF-1 for the increase in HR (DeltaHR), the decrease in QRS interval (DeltaQRS) and the decrease in QT (DeltaQT) interval. Adrenaline (nonselective beta-receptor agonist)-induced dysrhythmia was also significantly suppressed by ELF-EMF in MF-1 for the number of missing beats, the dysrhythmic ratio, and the increase in BP and PP. 5 These results indicated that 1-day exposure to ELF-EMF (60 Hz, 20 G) could suppress the increase in HR by affecting ventricular repolarization and may have a down-regulatory effect on responses of the cardiovascular system induced by sympathetic agonists.

  18. The effects of exposure to electromagnetic field on rat myocardium.

    PubMed

    Kiray, Amac; Tayefi, Hamid; Kiray, Muge; Bagriyanik, Husnu Alper; Pekcetin, Cetin; Ergur, Bekir Ugur; Ozogul, Candan

    2013-06-01

    Exposure to electromagnetic fields (EMFs) causes increased adverse effects on biological systems. The aim of this study was to investigate the effects of EMF on heart tissue by biochemical and histomorphological evaluations in EMF-exposed adult rats. In this study, 28 male Wistar rats weighing 200-250 g were used. The rats were divided into two groups: sham group (n = 14) and EMF group (n = 14). Rats in sham group were exposed to same conditions as the EMF group except the exposure to EMF. Rats in EMF group were exposed to a 50-Hz EMF of 3 mT for 4 h/day and 7 days/week for 2 months. After 2 months of exposure, rats were killed; the hearts were excised and evaluated. Determination of oxidative stress parameters was performed spectrophotometrically. To detect apoptotic cells, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) staining and caspase-3 immunohistochemistry were performed. In EMF-exposed group, levels of lipid peroxidation significantly increased and activities of superoxide dismutase and glutathione peroxidase decreased compared with sham group. The number of TUNEL-positive cells and caspase-3 immunoreactivity increased in EMF-exposed rats compared with sham. Under electron microscopy, there were mitochondrial degeneration, reduction in myofibrils, dilated sarcoplasmic reticulum and perinuclear vacuolization in EMF-exposed rats. In conclusion, the results show that the exposure to EMF causes oxidative stress, apoptosis and morphologic damage in myocardium of adult rats. The results of our study indicate that EMF-related changes in rat myocardium could be the result of increased oxidative stress. Further studies are needed to demonstrate whether the exposure to EMF can induce adverse effects on myocardium.

  19. Household electromagnetic fields and breast cancer in elderly women.

    PubMed

    Beniashvili, Djemal; Avinoach, Ilana; Baazov, David; Zusman, Itshak

    2005-01-01

    The relationship between the rate of household low-frequency electromagnetic fields (EMF) and incidences of mammary tumors was studied in 1290 clinical case-records of female patients aged 60 and more over a period of 26 years, based on the materials of the Edith Wolfson Medical Center, Israel. The studied material was divided into two groups, each corresponding to a period of 13 years. Group I included patients with mammary tumors under observation from 1978 to 1990, who rarely used EMF-generating appliances. Group II consisted of patients being under observation in the period between 1991 and 2003, characterized by much more extensive use of personal computers (more than 3 hours a day), mobile telephones, television sets, air conditioners and other household electrical appliances generating EMF. 200,527 biopsy and surgery samples were analyzed. Mammary tumors were found in 2824 women (1.4%), of which 1290 cases (45.6%) were observed in elderly women. Most of the observed tumors--1254 (97.2%)--were epithelial neoplasms. Mammary tumors were found in 585 elderly women in Group I and 705 women in Group II. The case records of these patients showed that 114 elderly women (19.5%) in Group I and 360 (51.1%) in Group II were regularly exposed to EMF (mostly from personal computers) for at least 3 hours a day (chi2=57.2, p<0.001). There was a statistically significant influence of EMF on the formation of all observed epithelial mammary tumors in Group II. This influence is most evident for invasive ductal carcinomas, which was the commonest form of cancer in elderly women.

  20. Radiofrequency-electromagnetic field exposures in kindergarten children.

    PubMed

    Bhatt, Chhavi Raj; Redmayne, Mary; Billah, Baki; Abramson, Michael J; Benke, Geza

    2017-09-01

    The aim of this study was to assess environmental and personal radiofrequency-electromagnetic field (RF-EMF) exposures in kindergarten children. Ten children and 20 kindergartens in Melbourne, Australia participated in personal and environmental exposure measurements, respectively. Order statistics of RF-EMF exposures were computed for 16 frequency bands between 88 MHz and 5.8 GHz. Of the 16 bands, the three highest sources of environmental RF-EMF exposures were: Global System for Mobile Communications (GSM) 900 MHz downlink (82 mV/m); Universal Mobile Telecommunications System (UMTS) 2100MHz downlink (51 mV/m); and GSM 900 MHz uplink (45 mV/m). Similarly, the three highest personal exposure sources were: GSM 900 MHz downlink (50 mV/m); UMTS 2100 MHz downlink, GSM 900 MHz uplink and GSM 1800 MHz downlink (20 mV/m); and Frequency Modulation radio, Wi-Fi 2.4 GHz and Digital Video Broadcasting-Terrestrial (10 mV/m). The median environmental exposures were: 179 mV/m (total all bands), 123 mV/m (total mobile phone base station downlinks), 46 mV/m (total mobile phone base station uplinks), and 16 mV/m (Wi-Fi 2.4 GHz). Similarly, the median personal exposures were: 81 mV/m (total all bands), 62 mV/m (total mobile phone base station downlinks), 21 mV/m (total mobile phone base station uplinks), and 9 mV/m (Wi-Fi 2.4 GHz). The measurements showed that environmental RF-EMF exposure levels exceeded the personal RF-EMF exposure levels at kindergartens.

  1. Personal radiofrequency electromagnetic field exposure measurements in Swiss adolescents.

    PubMed

    Roser, Katharina; Schoeni, Anna; Struchen, Benjamin; Zahner, Marco; Eeftens, Marloes; Fröhlich, Jürg; Röösli, Martin

    2017-02-01

    Adolescents belong to the heaviest users of wireless communication devices, but little is known about their personal exposure to radiofrequency electromagnetic fields (RF-EMF). The aim of this paper is to describe personal RF-EMF exposure of Swiss adolescents and evaluate exposure relevant factors. Furthermore, personal measurements were used to estimate average contributions of various sources to the total absorbed RF-EMF dose of the brain and the whole body. Personal exposure was measured using a portable RF-EMF measurement device (ExpoM-RF) measuring 13 frequency bands ranging from 470 to 3600MHz. The participants carried the device for three consecutive days and kept a time-activity diary. In total, 90 adolescents aged 13 to 17years participated in the study conducted between May 2013 and April 2014. In addition, personal measurement values were combined with dose calculations for the use of wireless communication devices to quantify the contribution of various RF-EMF sources to the daily RF-EMF dose of adolescents. Main contributors to the total personal RF-EMF measurements of 63.2μW/m(2) (0.15V/m) were exposures from mobile phones (67.2%) and from mobile phone base stations (19.8%). WLAN at school and at home had little impact on the personal measurements (WLAN accounted for 3.5% of total personal measurements). According to the dose calculations, exposure from environmental sources (broadcast transmitters, mobile phone base stations, cordless phone base stations, WLAN access points, and mobile phones in the surroundings) contributed on average 6.0% to the brain dose and 9.0% to the whole-body dose. RF-EMF exposure of adolescents is dominated by their own mobile phone use. Environmental sources such as mobile phone base stations play a minor role. Copyright © 2016 Elsevier Ltd. All rights reserved.

  2. A prediction model for personal radio frequency electromagnetic field exposure.

    PubMed

    Frei, Patrizia; Mohler, Evelyn; Bürgi, Alfred; Fröhlich, Jürg; Neubauer, Georg; Braun-Fahrländer, Charlotte; Röösli, Martin

    2009-12-15

    Radio frequency electromagnetic fields (RF-EMF) in our daily life are caused by numerous sources such as fixed site transmitters (e.g. mobile phone base stations) or indoor devices (e.g. cordless phones). The objective of this study was to develop a prediction model which can be used to predict mean RF-EMF exposure from different sources for a large study population in epidemiological research. We collected personal RF-EMF exposure measurements of 166 volunteers from Basel, Switzerland, by means of portable exposure meters, which were carried during one week. For a validation study we repeated exposure measurements of 31 study participants 21 weeks after the measurements of the first week on average. These second measurements were not used for the model development. We used two data sources as exposure predictors: 1) a questionnaire on potentially exposure relevant characteristics and behaviors and 2) modeled RF-EMF from fixed site transmitters (mobile phone base stations, broadcast transmitters) at the participants' place of residence using a geospatial propagation model. Relevant exposure predictors, which were identified by means of multiple regression analysis, were the modeled RF-EMF at the participants' home from the propagation model, housing characteristics, ownership of communication devices (wireless LAN, mobile and cordless phones) and behavioral aspects such as amount of time spent in public transports. The proportion of variance explained (R2) by the final model was 0.52. The analysis of the agreement between calculated and measured RF-EMF showed a sensitivity of 0.56 and a specificity of 0.95 (cut-off: 90th percentile). In the validation study, the sensitivity and specificity of the model were 0.67 and 0.96, respectively. We could demonstrate that it is feasible to model personal RF-EMF exposure. Most importantly, our validation study suggests that the model can be used to assess average exposure over several months.

  3. Effect of pulsed electromagnetic fields on endoplasmic reticulum stress.

    PubMed

    Keczan, E; Keri, G; Banhegyi, G; Stiller, I

    2016-10-01

    The maintenance of protein homeostasis in the endoplasmic reticulum (ER) is crucial in cell life. Disruption of proteostasis results in ER stress that activates the unfolded protein response (UPR); a signalling network assigned to manage the accumulated misfolded or unfolded proteins. Prolonged or unresolved ER stress leads to apoptotic cell death that can be the basis of many serious diseases. Our aim was to study the effect of pulsed electromagnetic fields (PEMF), an alternative, non-invasive therapeutic method on ER stressed cell lines. First, the effect of PEMF treatment on the expression of ER stress markers was tested in three different cell lines. PEMF had no remarkable effect on ER stress protein levels in human embryonic kidney (HEK293T) and human liver carcinoma (HepG2) cell lines. However, the expression of BiP, Grp94 and CHOP were increased in HeLa cells upon PEMF exposure. Therefore, HepG2 cell line was selected for further experiments. Cells were stressed by tunicamycin and exposed to PEMF. Grp94, PDI, CHOP and PARP expression as markers of stress were monitored by Western blot and cell viability was also investigated. Tunicamycin treatment, as expected, increased the expression of Grp94, PDI, CHOP and inactivated PARP. Analysis of protein expression showed that PEMF was able to decrease the elevated level of ER chaperons Grp94, PDI and the apoptosis marker CHOP. The truncated, inactive form of PARP was also decreased. Accordingly, cell viability was also improved by PEMF exposure. These results indicate that PEMF is able to moderate ER stress induced by tunicamycin in HepG2 cells. However, our results clearly draw attention to that different cell lines may vary in the response to PEMF treatment.

  4. Impact of high electromagnetic field levels on childhood leukemia incidence.

    PubMed

    Teepen, Jop C; van Dijck, Jos A A M

    2012-08-15

    The increasing exposure to electromagnetic fields (EMFs) has raised concern, as increased exposure may result in an increased risk of childhood leukemia (CL). Besides a short introduction of CL and EMF, our article gives an evaluation of the evidence of a causal relation between EMF and CL by critically appraising the epidemiological and biological evidence. The potential impact is also estimated by the population attributable risk. The etiology of CL is largely unknown, but is probably multifactorial. EMF may be one of the environmental exposures involved. Three pooled analyses of case-control studies showed a 1.4- to 1.7-fold increased CL risk for extremely low-frequency EMF (ELF-EMF) exposure levels above 0.3 μT. Several biases may have played a role in these studies, but are unlikely to fully explain the increased risk. For effects of radiofrequency ELF evidence is lacking. None of the proposed biological mechanisms by which ELF-EMF might cause CL have been confirmed. The estimated overall population attributable risk was 1.9%, with the highest estimates in Northern America and Brazil (4.2% and 4.1%, respectively). The potential impact of EMF exposure on public health is probably limited, although in some countries exposure might be relatively high and thus might have a more substantial impact. We recommend nationwide surveys to gain more insight into the contemporary exposure levels among children. Reducing exposure from power lines near densely populated areas and schools is advised. Future epidemiological studies should focus on limiting bias. Copyright © 2012 UICC.

  5. Induction of cell activation processes by low frequency electromagnetic fields.

    PubMed

    Simkó, Myrtill

    2004-10-20

    Electromagnetic fields (EMF) such as those from electric power transmission and distribution lines (50/60 Hz) have been associated with increased risk of childhood leukemia, cancer of the nervous system, and lymphomas. Several in vitro studies on EMF effects were performed to clarify the existing controversies, define the risks, and determine the possible mechanisms of adverse effects. In some of these reports, the effects were related to other mechanisms of carcinogenesis. Modification in cell proliferation was observed after EMF exposure and a few reports on cytotoxic effects have also been published. This limited review gives an overview of the current results of scientific research regarding in vitro studies on the effects of power line frequency EMF, but also cell biological mechanisms and their potential involvement in genotoxicity and cytotoxicity are discussed. Cell cycle control and signal transduction processes are included to elucidate the biochemical background of possible interactions. Exposure to EMF has been also linked to the incidence of leukemia and other tumors in some epidemiological studies and is considered as "possibly carcinogenic to humans", but there is no well-established biological mechanism that explains such a relation. Furthermore, EMF is also shown as a stimulus for immune relevant cells (e.g., macrophages) to release free radicals. It is known that chronic activation of macrophages is associated with the onset of phagocytosis and leads to increased formation of reactive oxygen species, which themselves may cause DNA damage and are suggested to lead to carcinogenesis. To demonstrate a possible interaction between EMF and cellular systems, we present a mechanistic model describing cell activation as a major importance for cellular response.

  6. Optical field enhancement by strong plasmon interaction in graphene nanostructures.

    PubMed

    Thongrattanasiri, Sukosin; García de Abajo, F Javier

    2013-05-03

    The ability of plasmons to enhance the electromagnetic field intensity in the gap between metallic nanoparticles derives from their strong optical confinement relative to the light wavelength. The spatial extension of plasmons in doped graphene has recently been shown to be boldly reduced with respect to conventional plasmonic metals. Here, we show that graphene nanostructures are capable of capitalizing such strong confinement to yield unprecedented levels of field enhancement, well beyond what is found in noble metals of similar dimensions (~ tens of nanometers). We perform realistic, quantum-mechanical calculations of the optical response of graphene dimers formed by nanodisks and nanotriangles, showing a strong sensitivity of the level of enhancement to the type of carbon edges near the gap region, with armchair edges favoring stronger interactions than zigzag edges. Our quantum-mechanical description automatically incorporates nonlocal effects that are absent in classical electromagnetic theory, leading to over an order of magnitude higher enhancement in armchair structures. The classical limit is recovered for large structures. We predict giant levels of light concentration for dimers ~200 nm, leading to infrared-absorption enhancement factors ~10(8). This extreme light enhancement and confinement in nanostructured graphene has great potential for optical sensing and nonlinear devices.

  7. Subwavelength confinement of electromagnetic field by guided modes of dielectric micro- and nanowaveguides

    NASA Astrophysics Data System (ADS)

    Zheltikov, A. M.

    2010-04-01

    Regimes enabling the strongest confinement of electromagnetic field by guided modes of dielectric micro- and nanowaveguides are identified. Waveguides of this class are shown to allow a guidance of subwavelength optical beams.

  8. Effect of radio frequency waves of electromagnetic field on the tubulin.

    PubMed

    Taghi, Mousavi; Gholamhosein, Riazi; Saeed, Rezayi-Zarchi

    2013-09-01

    Microtubules (MTs) are macromolecular structures consisting of tubulin heterodimers and present in almost every eukaryotic cell. MTs fulfill all conditions for generation of electromagnetic field and are electrically polar due to the electrical polarity of a tubulin heterodimer. The calculated static electric dipole moment of about 1000 Debye makes them capable of being aligned parallel to the applied electromagnetic field direction. In the present study, the tubulin heterodimers were extracted and purified from the rat brains. MTs were obtained by polymerization in vitro. Samples of microtubules were adsorbed in the absence and in the presence of electromagnetic fields with radio frequency of 900 Hz. Our results demonstrate the effect of electromagnetic field with 900 Hz frequency to change the structure of MTs. In this paper, a related patent was used that will help to better understand the studied subject.

  9. Characteristics of the electromagnetic wave field far away from the radiation source

    NASA Astrophysics Data System (ADS)

    Balkhanov, V. K.; Bashkuev, Yu. B.

    2017-04-01

    A solution to the Sommerfeld problem of the far (in terms of wavelengths) field of a vertical electrical dipole placed at the interface between two media has been found. The characteristics of a surface electromagnetic wave that propagates over a medium with highly inductive surface impedance δ have been determined. The spatial characteristics of the wave are expressed through the real and imaginary parts of impedance δ. It has been proved that the surface electromagnetic wave is the major contributor to the electromagnetic field of the ground wave in the case of highly inductive radio paths.

  10. Design and fabrication of helmholtz coils to study the effects of pulsed electromagnetic fields on the healing process in periodontitis: preliminary animal results.

    PubMed

    Haghnegahdar, A; Khosrovpanah, H; Andisheh-Tadbir, A; Mortazavi, Gh; Saeedi Moghadam, M; Mortazavi, Smj; Zamani, A; Haghani, M; Shojaei Fard, M; Parsaei, H; Koohi, O

    2014-09-01

    Effects of electromagnetic fields on healing have been investigated for centuries. Substantial data indicate that exposure to electromagnetic field can lead to enhanced healing in both soft and hard tissues. Helmholtz coils are devices that generate pulsed electromagnetic fields (PEMF). Objective : In this work, a pair of Helmholtz coils for enhancing the healing process in periodontitis was designed and fabricated. An identical pair of square Helmholtz coils generated the 50 Hz magnetic field.  This device was made up of two parallel coaxial circular coils (100 turns in each loop, wound in series) which were separated from each other by a distance equal to the radius of one coil (12.5 cm). The windings of our Helmholtz coil was made of standard 0.95mm wire to provide the maximum possible current. The coil was powered by a function generator.  The Helmholtz Coils generated a uniform magnetic field between its coils. The magnetic field strength at the center of the space between two coils was 97.6 μT. Preliminary biological studies performed on rats show that exposure of laboratory animals to pulsed electromagnetic fields enhanced the healing of periodontitis. Exposure to PEMFs can lead to stimulatory physiological effects on cells and tissues such as enhanced healing of periodontitis.

  11. Design and Fabrication of Helmholtz Coils to Study the Effects of Pulsed Electromagnetic Fields on the Healing Process in Periodontitis: Preliminary Animal Results

    PubMed Central

    Haghnegahdar, A; Khosrovpanah, H; Andisheh-Tadbir, A; Mortazavi, Gh; Saeedi Moghadam, M; Mortazavi, SMJ; Zamani, A; Haghani, M; Shojaei Fard, M; Parsaei, H; Koohi, O

    2014-01-01

    Background: Effects of electromagnetic fields on healing have been investigated for centuries. Substantial data indicate that exposure to electromagnetic field can lead to enhanced healing in both soft and hard tissues. Helmholtz coils are devices that generate pulsed electromagnetic fields (PEMF). Objective: In this work, a pair of Helmholtz coils for enhancing the healing process in periodontitis was designed and fabricated. Method: An identical pair of square Helmholtz coils generated the 50 Hz magnetic field.  This device was made up of two parallel coaxial circular coils (100 turns in each loop, wound in series) which were separated from each other by a distance equal to the radius of one coil (12.5 cm). The windings of our Helmholtz coil was made of standard 0.95mm wire to provide the maximum possible current. The coil was powered by a function generator.  Results: The Helmholtz Coils generated a uniform magnetic field between its coils. The magnetic field strength at the center of the space between two coils was 97.6 μT. Preliminary biological studies performed on rats show that exposure of laboratory animals to pulsed electromagnetic fields enhanced the healing of periodontitis. Conclusion: Exposure to PEMFs can lead to stimulatory physiological effects on cells and tissues such as enhanced healing of periodontitis. PMID:25505775

  12. Measurement of electromagnetic fields generated by air traffic control radar systems with spectrum analysers.

    PubMed

    Barellini, A; Bogi, L; Licitra, G; Silvi, A M; Zari, A

    2009-12-01

    Air traffic control (ATC) primary radars are 'classical' radars that use echoes of radiofrequency (RF) pulses from aircraft to determine their position. High-power RF pulses radiated from radar antennas may produce high electromagnetic field levels in the surrounding area. Measurement of electromagnetic fields produced by RF-pulsed radar by means of a swept-tuned spectrum analyser are investigated here. Measurements have been carried out both in the laboratory and in situ on signals generated by an ATC primary radar.

  13. [Mutagenic, carcinogenic and teratogenic effects induced by radiofrequency electromagnetic field of mobile phone].

    PubMed

    Chen, Zhi-jian; He, Ji-liang

    2008-01-01

    The extensive use of mobile phones causes increasing public concern on health effects of exposure to radiofrequency (RF) electromagnetic fields. Conflicting results are found in publications on the mutagenic, carcinogenic and teratogenic effects of RF electromagnetic fields. The overwhelming findings do not support the assumption that RF exposure may induce mutagenic, carcinogenic or teratogenic effects. However, health effects from low level RF exposure need to be further studied.

  14. Deuteron electromagnetic form factors in a renormalizable formulation of chiral effective field theory

    NASA Astrophysics Data System (ADS)

    Epelbaum, E.; Gasparyan, A. M.; Gegelia, J.; Schindler, M. R.

    2014-03-01

    We calculate the deuteron electromagnetic form factors in a modified version of Weinberg's chiral effective field theory approach to the two-nucleon system. We derive renormalizable integral equations for the deuteron without partial wave decomposition. Deuteron form factors are extracted by applying the Lehmann-Symanzik-Zimmermann reduction formalism to the three-point correlation function of deuteron interpolating fields and the electromagnetic current operator. Numerical results of a leading-order calculation with removed cutoff regularization agree well with experimental data.

  15. [Ecological significance of electromagnetic fields: the 20th century--century of electricity, the 21st--century of magnetism].

    PubMed

    Lazetić, Bogosav

    2003-01-01

    The biosphere consists of all ecosystems of earth and is characterized by electromagnetic fields of different frequencies. Physics and natural sciences and disciplines are focused on their origin and characteristics. NATURAL ELECTROMAGNETIC FIELDS: There is a well defined idea that natural electromagnetic activity of the Earth's atmosphere throughout evolution led to appearance of electromagnetic homeostasis, i.e. maintenance of inner electromagnetic mileu. It can be supposed that during the evolution of living organisms natural electromagnetic fields were associated with biochemical processes and as a result of natural selection became an important information system and obligatory component of life. The results presented here show that there is no reason to doubt that natural electromagnetic fields are an important ecologic factor. On the contrary, we have to emphasize that natural electromagnetic environment is necessary for life on the Earth. Today intensity of artificial electromagnetic fields is ten to hundred times higher than of natural electromagnetic fields. Danger from electromagnetic fields is an acute and actual problem which increases knowing that there won't be a spot without artificial electromagnetic field on our planet.

  16. Novel electromagnetic field probes with ultrasonic transmission lines for field measurements with minimum interaction

    NASA Astrophysics Data System (ADS)

    Dürr, W.; Oppelt, R.

    1990-02-01

    Electromagnetic field probes are described which use ultrasonic transmission lines for signal transmission from a small electric or magnetic measuring dipole to the data processing unit. These transmission lines are made of nonmetallic material with low permittivity and permeability so that its interaction with the field to be measured is minimum. In particular, there is no evidence of energy leakage via surface or sheath waves, which normally cause problems when usual metallic connecting cables are used. This is especially important when measuring near fields of antennas or fields in resonators with high Q factors. Wide-band operation was achieved by amplitude modulating the field to be measured at a low frequency. The purpose of this modulation is to create a low-frequency (kHz) signal which can be transmitted via an ultrasonic line, designed to resonate at this low frequency. The radio frequency (rf) itself can extend over a broad range since the ultrasonic line does not transmit this frequency directly. Since the ultrasonic line is operated at a low frequency, its design and manufacture including ultrasonic transducers are essentially simple, even for field probes working in the gigahertz range. The design of the transmission line and of the measuring dipoles with demodulation circuitry are described. The probe performance is discussed for a magnetic field probe used for field measurements in resonant antennas for magnetic resonance imaging in the frequency range up to about 200 MHz. A typical field measurement result is presented for this application.

  17. Calculation of electromagnetic fields in the near-field region of a moving scattering object

    NASA Astrophysics Data System (ADS)

    Vogel, M. H.

    1990-07-01

    The problem of scattering of electromagnetic fields by perfectly conducting, moving objects is solved with the Lorentz transformation and the plane wave formulation. Apart from the physical optics approximation, the solution is exact. The result is subsequently applied to the special case of monostatic reflection by an object that moves slowly with respect to the velocity of light. The result can be used to predict the time dependent reflection from an aircraft that passes the antenna of a proximity fuze, and the optimum fuze algorithm can be selected.

  18. Ultrafocused Electromagnetic Field Pulses with a Hollow Cylindrical Waveguide

    NASA Astrophysics Data System (ADS)

    Maurer, P.; Prat-Camps, J.; Cirac, J. I.; Hänsch, T. W.; Romero-Isart, O.

    2017-07-01

    We theoretically show that a dipole externally driven by a pulse with a lower-bounded temporal width, and placed inside a cylindrical hollow waveguide, can generate a train of arbitrarily short and focused electromagnetic pulses. The waveguide encloses vacuum with perfect electric conducting walls. A dipole driven by a single short pulse, which is properly engineered to exploit the linear spectral filtering of the cylindrical hollow waveguide, excites longitudinal waveguide modes that are coherently refocused at some particular instances of time, thereby producing arbitrarily short and focused electromagnetic pulses. We numerically show that such ultrafocused pulses persist outside the cylindrical waveguide at distances comparable to its radius.

  19. Grounding system analysis in transients programs applying electromagnetic field approach

    SciTech Connect

    Heimbach, M.; Grcev, L.D.

    1997-01-01

    Lightning protection studies of substations and power systems require knowledge of the dynamic behavior of large grounding grids during electromagnetic transients. This paper presents strategies which allow to incorporate complex grounding structures computed using a rigorous electromagnetic model in transients programs. A novel technique for rational function representation of frequency-dependent grounding system impedances in the EMTP is described. An arbitrary number of feeding points can be modeled as mutual coupling is taken into account. Overvoltages throughout electrical power systems and the transient ground potential rise in the surroundings of grounding structures can be computed.

  20. Hearing aids' electromagnetic immunity to environmental RF fields.

    PubMed

    Facta, S; Benedetto, A; Anglesio, L; d'Amore, G

    2004-01-01

    In this work, the electromagnetic interference on hearing aids was evaluated. Electromagnetic (EM) immunity tests on different types of hearing aids were carried out, using signals of intensity and modulation comparable to those present in the environment. The purpose of this work is to characterise the interference, establishing the immunity threshold for different frequencies and finding out which types of hearing aids are more susceptible, and in which frequency range. The tests were carried out in a GTEM cell on seven hearing aids, using AM and GSM signals in the radiofrequency (RF) range.

  1. Regulation of osteogenic differentiation of human adipose-derived stem cells by controlling electromagnetic field conditions

    PubMed Central

    Kang, Kyung Shin; Hong, Jung Min; Kang, Jo A; Rhie, Jong-Won; Jeong, Young Hun; Cho, Dong-Woo

    2013-01-01

    Many studies have reported that an electromagnetic field can promote osteogenic differentiation of mesenchymal stem cells. However, experimental results have differed depending on the experimental and environmental conditions. Optimization of electromagnetic field conditions in a single, identified system can compensate for these differences. Here we demonstrated that specific electromagnetic field conditions (that is, frequency and magnetic flux density) significantly regulate osteogenic differentiation of adipose-derived stem cells (ASCs) in vitro. Before inducing osteogenic differentiation, we determined ASC stemness and confirmed that the electromagnetic field was uniform at the solenoid coil center. Then, we selected positive (30/45 Hz, 1 mT) and negative (7.5 Hz, 1 mT) osteogenic differentiation conditions by quantifying alkaline phosphate (ALP) mRNA expression. Osteogenic marker (for example, runt-related transcription factor 2) expression was higher in the 30/45 Hz condition and lower in the 7.5 Hz condition as compared with the nonstimulated group. Both positive and negative regulation of ALP activity and mineralized nodule formation supported these responses. Our data indicate that the effects of the electromagnetic fields on osteogenic differentiation differ depending on the electromagnetic field conditions. This study provides a framework for future work on controlling stem cell differentiation. PMID:23306704

  2. Coupling of translational and rotational motion in chiral liquids in electromagnetic and circularly polarised electric fields.

    PubMed

    English, Niall J; Kusalik, Peter G; Woods, Sarah A

    2012-03-07

    Non-equilibrium molecular dynamics simulations of R and S enantiomers of 1,1-chlorofluoroethane, both for pure liquids and racemic mixtures, have been performed at 298 K in the absence and presence of both electromagnetic (e/m) and circularly polarised electric (CP) fields of varying frequency (100-2200 GHz) and intensity (0.025-0.2 V Å(-1) (rms)). Significant non-thermal field effects were noted in the coupling of rotational and translational motion; for instance, in microwave and far-infrared (MW/IR) e/m fields, marked increases in rotational and translational diffusion vis-à-vis the zero-field case took place at 0.025-0.1 V Å(-1) (rms), with a reduction in translational diffusion vis-à-vis the zero-field case above 0.1 V Å(-1) (rms) above 100 GHz. This was due to enhanced direct coupling of rotational motion with the more intense e/m field at the ideal intrinsic rotational coupling frequency (approximately 700 GHz) leading to such rapidly oscillating rotational motion that extent of translational motion was effectively reduced. In the case of CP fields, rotational and translational diffusion was also enhanced for all intensities, particularly at approximately 700 GHz. For both MW/IR and CP fields, non-linear field effects were evident above around 0.1 V Å(-1) (rms) intensity, in terms of enhancements in translational and rotational motion. Simulation of 90-10 mol. % liquid mixtures of a Lennard-Jones solvent with R and S enantiomer-solutes in MW/IR and CP fields led to more limited promotion of rotational and translational diffusion, due primarily to increased frictional effects. For both e/m and CP fields, examination of the laboratory- and inertial-frame auto- and cross-correlation functions of velocity and angular velocity demonstrated the development of explicit coupling with the external fields at the applied frequencies, especially so in the more intense fields where nonlinear effects come into play. For racemic mixtures, elements of the laboratory

  3. Effect of hydrostatic pressure and magnetic field on electromagnetically induced transparency based nonlinear frequency conversion in quantum ring

    NASA Astrophysics Data System (ADS)

    Gumber, Sukirti; Gambhir, Monica; Jha, Pradip Kumar; Mohan, Man

    2016-10-01

    We study the combined effect of hydrostatic pressure and magnetic field on electromagnetically induced transparency in quantum ring. The high flexibility in size and shape of ring makes it possible to fabricate a nearly perfect two-dimensional quantum structure. We also explore the dependence of frequency conversion, measured in terms of third order nonlinear susceptibility χ(3) , on coupling field, hydrostatic pressure and magnetic field. Although, a dip in χ(3) is observed with the introduction of strong coupling field, it renders the ring structure transparent to generated wave thus effectively enhancing the output of nonlinear frequency conversion process. At a fixed coupling strength, the output can be further enhanced by increasing the magnetic field while it shows an inverse relationship with pressure. These parameters, being externally controlled, provide an easy handle to control the output of quantum ring which can be used as frequency converter in communication networks.

  4. Superresolution of buried objects in layered media by near-field electromagnetic imaging

    NASA Astrophysics Data System (ADS)

    Lehman, Sean Kenneth

    In non-invasive wave† probing of layered media in near field conditions, few researchers outside of optical microscopists have taken advantage of the evanescent part of the scattered field to enhance resolution. In this dissertation, we propose and develop an imaging technique to be used in near-field environments which achieves resolution beyond the diffraction limit, or equivalently ``superresolution,'' by including the evanescent part of the field backscattered from objects buried in the medium. In Chapter 1, we discuss the nature of non-invasive wave probing of objects and introduce the concept of tomography. Tomographic imaging is a collection of techniques to reconstruct images of the unknown internal structure of an object from fields transmitted through, and/or reflected from it. We develop two widely used tomographic techniques: projection tomography and plane to plane backpropagation. In Chapter 2, we introduce and develop the concept of inhomogeneous diffraction tomography, the area with which this dissertation is concerned. We show the most widely used diffraction tomography technique is resolution limited to approximately a half wavelength. In Chapter 3, we study the forward scattering process in order to develop a new diffraction tomography imaging technique which achieves resolution beyond the classical limit. We propose and prove a new theorem which explains why the diffraction tomography method of Chapter 2 is resolution limited. We then derive a total field scattering relation which includes both propagating and evanescent field components. In Chapter 4, we develop a new reconstruction algorithm which is based upon the total field scattering relation. This full field tomographic reconstruction algorithm includes both propagating and evanescent field components. In Chapter 5, we present reconstruction results from both simulated and real wide-band radar data which demonstrate our new algorithm surpasses the resolution of most current techniques

  5. Electromagnetic model and calculations of the surface-enhanced Raman-shifted emission from Langmuir-Blodgett films on metal nanostructures

    NASA Astrophysics Data System (ADS)

    Giannini, V.; Sánchez-Gil, J. A.; García-Ramos, J. V.; Méndez, E. R.

    2007-07-01

    We present a theoretical study of the electromagnetic contribution to surface-enhanced Raman scattering (SERS) from a Langmuir-Blodgett film close to a metal surface. This macroscopic dipolar model fully accounts for the Raman-shifted emission so that meaningful SERS (electromagnetic) enhancement factors that do not depend only on the local electromagnetic field enhancement at the pump frequency are defined. For a plane metal surface, analytical SERS enhancement factors that are consistent for all pump beam polarization and molecular orientation are obtained. In order to investigate SERS on complex nanostructured metal surfaces, we introduce this model into the formally exact, Green's theorem surface integral equation formulation of the scattered electromagnetic field. This formulation is thus employed to calculate numerically the near-field and far-field emissions at the Raman-shifted frequency for very rough, random nanostructured surfaces, with emphasis on the impact of collective processes for varying pump frequency and Raman shift. Our results reveal that the widely used ∣E∣4 approximation tends to overestimate average SERS enhancement factors.

  6. Electromagnetically Driven Plasma-Field Dynamics in Modified Ionosphere

    NASA Astrophysics Data System (ADS)

    Kochetov, Andrey; Terina, Galina

    Under sounding of an artificial ionospheric turbulence by short probing radio pulses of ordinary polarization the two types of scattered signals were observed: a "caviton" signal (CS) and a "plasma" signal (PS), which appeared with the heating transmitter switching on and disap-peared after its switching off (G.I. Terina J. Atm. Terr. Phys, 57, 1995, 273, Izv. VUZov, Radiofizika, 39, 1998, 203). The scattered signal of PS type was revealed also after the heating switching off. It was called an "aftereffect plasma signal" (AEPS) (G.I. Terina Izv .VUZov, Radiofizika, 43, 2000, 958). This signal had large time and spatial delays and appeared mostly when corresponding PS had envelope fluctuations. The aftereffect phenomenon was expressed at time on CS by amplitude increasing at once after the heating transmitter turning off. The theoretical model of this phenomenon is proposed in and some peculiarities of the aftereffect phenomena of the scattered signals in modified ionospheric plasma are considered and discussed. For theoretical interpretation of the characteristics of CS and AEPS the numerical solution of nonlinear Shrüdinger equation (NSE) with driven extension were carried out in inhomogeneous plasma layer with linear electron density profile (A.V. Kochetov, V.A. Mironov, G.I. Terina, Adv. Space Reseacrh, 29, 2002, 1369) and for the one with prescribed density depletion (and A.V. Kochetov, G.I. Terina, Adv. Space Reseacrh, 38, 2006, 2490). The simulation results obtained for linear inhomogeneous plasma layer and for plasma one with density depletion al-low us to interpret the aftereffect of CS and PS qualitatively. The field amplitude increase at relaxation stage displayed at calculations allows us to interpret of CS aftereffect. The large time delays of AEPS can be explained as a result of powerful radio waves trapping in the forming at the plasma resonance regions density depletions (E. Mjøhus, J. Geophys. Res. 103, 1998, 14711; B. Eliasson and L. Stenflo, J

  7. Amyotrophic lateral sclerosis and occupational exposure to electromagnetic fields

    SciTech Connect

    Davanipour, Z.; Sobel, E.; Bowman, J.D.; Qian, Z.; Will, A.D.

    1997-03-01

    In an hypothesis-generating case-control study of amyotrophic lateral sclerosis, lifetime occupational histories were obtained. The patients (n = 28) were clinic based. The occupational exposure of interest in this report is electromagnetic fields (EMFs). This is the first and so far the only exposure analyzed in this study. Occupational exposure up to 2 years prior to estimated disease symptom onset was used for construction of exposure indices for cases. Controls (n = 32) were blood and nonblood relatives of cases. Occupational exposure for controls was through the same age as exposure for the corresponding cases. Twenty (71%) cases and 28 (88%) controls had at least 20 years of work experience covering the exposure period. The occupational history and task data were used to classify blindly each occupation for each subject as having high, medium/high, medium, medium/low, or low EMF exposure, based primarily on data from an earlier and unrelated study designed to obtain occupational EMF exposure information on workers in ``electrical`` and ``nonelectrical`` jobs. By using the length of time each subject spent in each occupation through the exposure period, two indices of exposure were constructed: total occupational exposure (E{sub 1}) and average occupational exposure (E{sub 2}). For cases and controls with at least 20 years of work experience, the odds ratio (OR) for exposure at the 75th percentile of the E{sub 1} case exposure data relative to minimum exposure was 7.5 (P < 0.02; 95% CI, 1.4--38.1) and the corresponding OR for E{sub 2} was 5.5 (P < 0.02; 95% CI, 1.3--22.5). For all cases and controls, the ORs were 2.5 (P < 0.1; 95% CI, 0.9--8.1) for E{sub 1} and 2.3 (P = 0.12; 95% CI, 0.8--6.6) for E{sub 2}. This study should be considered an hypothesis-generating study. Larger studies, using incident cases and improved exposure assessment, should be undertaken.

  8. 1800 MHz electromagnetic field effects on melatonin release from isolated pineal glands.

    PubMed

    Sukhotina, Irina; Streckert, Joachim R; Bitz, Andreas K; Hansen, Volkert W; Lerchl, Alexander

    2006-01-01

    Isolated pineal glands of Djungarian hamsters (Phodopus sungorus) were continuously perifused by Krebs-Ringer buffer, stimulated with the beta-adrenergic receptor agonist isoproterenol to induce melatonin synthesis, and exposed for 7 hr to a 1800 MHz continuous wave (CW) or pulsed GSM (Global System for Mobile Communications)-modulated electromagnetic signal at specific absorption rate (SAR) rates of 8, 80, 800, and 2700 mW/kg. Experiments were performed in a blind fashion. Perifusate samples were collected every hour, and melatonin concentrations were measured by a specific radioimmunoassay. Both types of signal significantly enhanced melatonin release at 800 mW/kg SAR, while at 2700 mW/kg SAR, melatonin levels were elevated in the CW, but suppressed in the GSM-exposed pineal glands. As a temperature rise of approximately 1.2 degrees C was measured at 2700 mW/kg SAR, effects at this level are thermal. With regard to radiofrequency electromagnetic fields, the data do not support the 'melatonin hypothesis,' according to which nonthermal exposure suppresses melatonin synthesis.

  9. A Note on Feynman Path Integral for Electromagnetic External Fields

    NASA Astrophysics Data System (ADS)

    Botelho, Luiz C. L.

    2017-08-01

    We propose a Fresnel stochastic white noise framework to analyze the nature of the Feynman paths entering on the Feynman Path Integral expression for the Feynman Propagator of a particle quantum mechanically moving under an external electromagnetic time-independent potential.

  10. Localized Electromagnetic Fields in Complex Media and Free Space

    DTIC Science & Technology

    2000-09-29

    subsets-termed "storms", "whirls", and " tornadoes " for the sake of brevity-for which time average energy flux is identically zero at all points...speed V <C. The solutions which describe finite-energy evolving electromagnetic storms, whirls, tornadoes are also presented.

  11. Coupling Mechanism of Electromagnetic Field and Thermal Stress on Drosophila melanogaster.

    PubMed

    Zhang, Zi-Yan; Zhang, Jing; Yang, Chuan-Jun; Lian, Hui-Yong; Yu, Hui; Huang, Xiao-Mei; Cai, Peng

    2016-01-01

    Temperature is an important factor in research on the biological effects of extremely low-frequency electromagnetic field (ELF-EMF), but interactions between ELF-EMF and temperature remain unknown. The effects of ELF-EMF (50 Hz, 3 mT) on the lifespan, locomotion, heat shock response (HSR), and oxidative stress (OS) of Canton-Special (CS) and mutant w1118 flies were investigated at 25°C and 35°C (thermal stress). Results showed that thermal stress accelerated the death rates of CS and w1118 flies, shortened their lifespan, and influenced their locomotion rhythm and activity. The upregulated expression levels of heat shock protein (HSP) 22, HSP26, and HSP70 indicated that HSR was enhanced. Thermal stress-induced OS response increased malondialdehyde content, enhanced superoxide dismutase activity, and decreased reactive oxygen species level. The effects of thermal stress on the death rates, lifespan, locomotion, and HSP gene expression of flies, especially w1118 line, were also enhanced by ELF-EMF. In conclusion, thermal stress weakened the physiological function and promoted the HSR and OS of flies. ELF-EMF aggravated damages and enhanced thermal stress-induced HSP and OS response. Therefore, thermal stress and ELF-EMF elicited a synergistic effect.

  12. Coupling Mechanism of Electromagnetic Field and Thermal Stress on Drosophila melanogaster

    PubMed Central

    Yang, Chuan-Jun; Lian, Hui-Yong; Yu, Hui; Huang, Xiao-Mei; Cai, Peng

    2016-01-01

    Temperature is an important factor in research on the biological effects of extremely low-frequency electromagnetic field (ELF-EMF), but interactions between ELF-EMF and temperature remain unknown. The effects of ELF-EMF (50 Hz, 3 mT) on the lifespan, locomotion, heat shock response (HSR), and oxidative stress (OS) of Canton-Special (CS) and mutant w1118 flies were investigated at 25°C and 35°C (thermal stress). Results showed that thermal stress accelerated the death rates of CS and w1118 flies, shortened their lifespan, and influenced their locomotion rhythm and activity. The upregulated expression levels of heat shock protein (HSP) 22, HSP26, and HSP70 indicated that HSR was enhanced. Thermal stress-induced OS response increased malondialdehyde content, enhanced superoxide dismutase activity, and decreased reactive oxygen species level. The effects of thermal stress on the death rates, lifespan, locomotion, and HSP gene expression of flies, especially w1118 line, were also enhanced by ELF-EMF. In conclusion, thermal stress weakened the physiological function and promoted the HSR and OS of flies. ELF-EMF aggravated damages and enhanced thermal stress-induced HSP and OS response. Therefore, thermal stress and ELF-EMF elicited a synergistic effect. PMID:27611438

  13. Enhanced nonlinear interaction of powerful electromagnetic waves with ionospheric plasma near the second electron gyroharmonic

    SciTech Connect

    Istomin, Ya. N.; Leyser, T. B.

    2013-05-15

    Plasma experiments in which a powerful electromagnetic pump wave is transmitted into the ionosphere from the ground give access to a rich range of phenomena, including gyroharmonic effects when the pump frequency is near an harmonic of the ionospheric electron gyrofrequency. For pump frequencies close to the second gyroharmonic, experiments show a strong enhancement, as observed in radar scatter from pump-induced geomagnetic field-aligned density striations and optical emissions. This is in contrast to the case at the third harmonic and higher at which most of the effects are instead suppressed. We show theoretically that electrostatic oscillations can be localized in density inhomogeneities associated with small scale striations. The localized field is a mixture of the electron Bernstein and upper hybrid modes when the pump frequency is near the second gyroharmonic. The coupling of the modes is enabled by a symmetry feature of the linear electron Bernstein and upper hybrid dispersion properties that occur only near the second gyroharmonic. Electron acceleration inside the density inhomogeneities by localized azimuthal electrostatic oscillations is more efficient near the second gyroharmonic than at higher frequencies, consistent with the observed enhancements.

  14. Transient effect of weak electromagnetic fields on calcium ion concentration in Arabidopsis thaliana.

    PubMed

    Pazur, Alexander; Rassadina, Valentina

    2009-04-30

    Weak magnetic and electromagnetic fields can influence physiological processes in animals, plants and microorganisms, but the underlying way of perception is poorly understood. The ion cyclotron resonance is one of the discussed mechanisms, predicting biological effects for definite frequencies and intensities of electromagnetic fields possibly by affecting the physiological availability of small ions. Above all an influence on Calcium, which is crucial for many life processes, is in the focus of interest. We show that in Arabidopsis thaliana, changes in Ca2+-concentrations can be induced by combinations of magnetic and electromagnetic fields that match Ca2+-ion cyclotron resonance conditions. An aequorin expressing Arabidopsis thaliana mutant (Col0-1 Aeq Cy+) was subjected to a magnetic field around 65 microtesla (0.65 Gauss) and an electromagnetic field with the corresponding Ca2+ cyclotron frequency of 50 Hz. The resulting changes in free Ca2+ were monitored by aequorin bioluminescence, using a high sensitive photomultiplier unit. The experiments were referenced by the additional use of wild type plants. Transient increases of cytosolic Ca2+ were observed both after switching the electromagnetic field on and off, with the latter effect decreasing with increasing duration of the electromagnetic impact. Compared with this the uninfluenced long-term loss of bioluminescence activity without any exogenic impact was negligible. The magnetic field effect rapidly decreased if ion cyclotron resonance conditions were mismatched by varying the magnetic fieldstrength, also a dependence on the amplitude of the electromagnetic component was seen. Considering the various functions of Ca2+ as a second messenger in plants, this mechanism may be relevant for perception of these combined fields. The applicability of recently hypothesized mechanisms for the ion cyclotron resonance effect in biological systems is discussed considering it's operating at magnetic field strengths weak

  15. Transient effect of weak electromagnetic fields on calcium ion concentration in Arabidopsis thaliana

    PubMed Central

    Pazur, Alexander; Rassadina, Valentina

    2009-01-01

    Background Weak magnetic and electromagnetic fields can influence physiological processes in animals, plants and microorganisms, but the underlying way of perception is poorly understood. The ion cyclotron resonance is one of the discussed mechanisms, predicting biological effects for definite frequencies and intensities of electromagnetic fields possibly by affecting the physiological availability of small ions. Above all an influence on Calcium, which is crucial for many life processes, is in the focus of interest. We show that in Arabidopsis thaliana, changes in Ca2+-concentrations can be induced by combinations of magnetic and electromagnetic fields that match Ca2+-ion cyclotron resonance conditions. Results An aequorin expressing Arabidopsis thaliana mutant (Col0-1 Aeq Cy+) was subjected to a magnetic field around 65 microtesla (0.65 Gauss) and an electromagnetic field with the corresponding Ca2+ cyclotron frequency of 50 Hz. The resulting changes in free Ca2+ were monitored by aequorin bioluminescence, using a high sensitive photomultiplier unit. The experiments were referenced by the additional use of wild type plants. Transient increases of cytosolic Ca2+ were observed both after switching the electromagnetic field on and off, with the latter effect decreasing with increasing duration of the electromagnetic impact. Compared with this the uninfluenced long-term loss of bioluminescence activity without any exogenic impact was negligible. The magnetic field effect rapidly decreased if ion cyclotron resonance conditions were mismatched by varying the magnetic fieldstrength, also a dependence on the amplitude of the electromagnetic component was seen. Conclusion Considering the various functions of Ca2+ as a second messenger in plants, this mechanism may be relevant for perception of these combined fields. The applicability of recently hypothesized mechanisms for the ion cyclotron resonance effect in biological systems is discussed considering it's operating at

  16. The Effect of Direct Lightning Shielding Rod on Lightning Electromagnetic Fields Aboveground

    NASA Astrophysics Data System (ADS)

    Fu, Ya-Peng; Gao, Cheng; Yang, Bo

    2017-09-01

    A practical new type direct lightning shielding rod is designed to reduce the electromagnetic radiation produced by lightning stroking to Franklin lightning rod in the paper. The Finite-Difference Time-Domain (FDTD) method is adopted for analyzing. It is the shielding layer that affects the electromagnetic fields and the insulating medium make no difference. All the electromagnetic fields amplitude obtained decrease for the shielding layer existing, regardless of any condition, but the extent is different. That is, the effect on the horizontal electric field is most noticeable, the vertical electric field comes second, minimum the azimuthal magnetic field. All the field components are affected by shielding layer height and the distance between shielding layer and lightning channel, but not significantly by the shielding layer grounding depth. The shielding effect is more obvious with lower ground conductivity, but the ground relative permittivity makes no difference.

  17. Influence of Electric, Magnetic, and Electromagnetic Fields on the Circadian System: Current Stage of Knowledge

    PubMed Central

    Żak, Arkadiusz

    2014-01-01

    One of the side effects of each electrical device work is the electromagnetic field generated near its workplace. All organisms, including humans, are exposed daily to the influence of different types of this field, characterized by various physical parameters. Therefore, it is important to accurately determine the effects of an electromagnetic field on the physiological and pathological processes occurring in cells, tissues, and organs. Numerous epidemiological and experimental data suggest that the extremely low frequency magnetic field generated by electrical transmission lines and electrically powered devices and the high frequencies electromagnetic radiation emitted by electronic devices have a potentially negative impact on the circadian system. On the other hand, several studies have found no influence of these fields on chronobiological parameters. According to the current state of knowledge, some previously proposed hypotheses, including one concerning the key role of melatonin secretion disruption in pathogenesis of electromagnetic field induced diseases, need to be revised. This paper reviews the data on the effect of electric, magnetic, and electromagnetic fields on melatonin and cortisol rhythms—two major markers of the circadian system as well as on sleep. It also provides the basic information about the nature, classification, parameters, and sources of these fields. PMID:25136557

  18. Influence of electric, magnetic, and electromagnetic fields on the circadian system: current stage of knowledge.

    PubMed

    Lewczuk, Bogdan; Redlarski, Grzegorz; Zak, Arkadiusz; Ziółkowska, Natalia; Przybylska-Gornowicz, Barbara; Krawczuk, Marek

    2014-01-01

    One of the side effects of each electrical device work is the electromagnetic field generated near its workplace. All organisms, including humans, are exposed daily to the influence of different types of this field, characterized by various physical parameters. Therefore, it is important to accurately determine the effects of an electromagnetic field on the physiological and pathological processes occurring in cells, tissues, and organs. Numerous epidemiological and experimental data suggest that the extremely low frequency magnetic field generated by electrical transmission lines and electrically powered devices and the high frequencies electromagnetic radiation emitted by electronic devices have a potentially negative impact on the circadian system. On the other hand, several studies have found no influence of these fields on chronobiological parameters. According to the current state of knowledge, some previously proposed hypotheses, including one concerning the key role of melatonin secretion disruption in pathogenesis of electromagnetic field induced diseases, need to be revised. This paper reviews the data on the effect of electric, magnetic, and electromagnetic fields on melatonin and cortisol rhythms-two major markers of the circadian system as well as on sleep. It also provides the basic information about the nature, classification, parameters, and sources of these fields.

  19. Exposure of biological preparations to radiofrequency electromagnetic fields under low gravity.

    PubMed

    Jacquot, Jean Francois; le Bail, Jean-Luc; Bardet, Michel; Tabony, James

    2010-11-01

    There is interest as to whether the electromagnetic fields used in mobile radiotelephony might affect biological processes. Other weak fields such as gravity intervene in a number of physical and biological processes. Under appropriate in vitro conditions, the macroscopic self-organization of microtubules, a major cellular component, is triggered by gravity. We wished to investigate whether self-organization might also be affected by radiotelephone electromagnetic fields. Detecting a possible effect requires removing the obscuring effects triggered by gravity. A simple manner of doing this is by rotating the sample about the horizontal. However, if the external field does not also rotate with the sample, its possible effect might also be averaged down by rotation. Here, we describe an apparatus in which both the sample and an applied radiofrequency electromagnetic field (1.8 GHz) are stationary with respect to one another while undergoing horizontal rotation. The electromagnetic field profile within the apparatus has been measured and the apparatus tested by reproducing the in vitro behavior of microtubule preparations under conditions of weightlessness. Specific adsorption rates of electromagnetic energy within a sample are measured from the initial temperature rise the incident field causes. The apparatus can be readily adapted to expose samples to various other external fields and factors under conditions of weightlessness.

  20. Exposure to an extremely low-frequency electromagnetic field only slightly modifies the proteome of Chromobacterium violaceumATCC 12472.

    PubMed

    Baraúna, Rafael A; Santos, Agenor V; Graças, Diego A; Santos, Daniel M; Ghilardi, Rubens; Pimenta, Adriano M C; Carepo, Marta S P; Schneider, Maria P C; Silva, Artur

    2015-05-01

    Several studies of the physiological responses of different organisms exposed to extremely low-frequency electromagnetic fields (ELF-EMF) have been described. In this work, we report the minimal effects of in situ exposure to ELF-EMF on the global protein expression of Chromobacterium violaceum using a gel-based proteomic approach. The protein expression profile was only slightly altered, with five differentially expressed proteins detected in the exposed cultures; two of these proteins (DNA-binding stress protein, Dps, and alcohol dehydrogenase) were identified by MS/MS. The enhanced expression of Dps possibly helped to prevent physical damage to DNA. Although small, the changes in protein expression observed here were probably beneficial in helping the bacteria to adapt to the stress generated by the electromagnetic field.

  1. Exposure to an extremely low-frequency electromagnetic field only slightly modifies the proteome of Chromobacterium violaceumATCC 12472

    PubMed Central

    Baraúna, Rafael A.; Santos, Agenor V.; Graças, Diego A.; Santos, Daniel M.; Ghilardi, Rubens; Pimenta, Adriano M. C.; Carepo, Marta S. P.; Schneider, Maria P.C.; Silva, Artur

    2015-01-01

    Several studies of the physiological responses of different organisms exposed to extremely low-frequency electromagnetic fields (ELF-EMF) have been described. In this work, we report the minimal effects of in situ exposure to ELF-EMF on the global protein expression of Chromobacterium violaceum using a gel-based proteomic approach. The protein expression profile was only slightly altered, with five differentially expressed proteins detected in the exposed cultures; two of these proteins (DNA-binding stress protein, Dps, and alcohol dehydrogenase) were identified by MS/MS. The enhanced expression of Dps possibly helped to prevent physical damage to DNA. Although small, the changes in protein expression observed here were probably beneficial in helping the bacteria to adapt to the stress generated by the electromagnetic field. PMID:26273227

  2. Electromagnetics

    DTIC Science & Technology

    2013-03-05

    research provides optimism regarding a class of composite magnetic materials displaying significantly reduced losses • Antenna Design/Operation...Vitebskiy (AFRL/RY) “Metamaterials for the Enhancement of Light-Matter Interaction” Performance enhancement of various transceivers Dr...NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Air Force Office of Scientific Research ,AFOSR/RTB,875 N. Randolph

  3. Finite Element Method Simulations of the Near-Field Enhancement at the Vicinity of Fractal Rough Metallic Surfaces

    SciTech Connect

    Micic, Miodrag; Klymyshyn, Nicholas A.; Lu, H PETER.

    2004-03-04

    Near-field optical enhancement at metal surfaces and methods such as surface plasmon resonance (SPR), surface-enhanced Raman scattering (SERS), fluorescent quenching and enhancement, and various near-field scanning microscopies (NSOM) all depend on a metals surface properties, mainly on its morphology and SPR resonant frequency. We report on simulations of the influence of different surface morphologies on electromagnetic field enhancements at the rough surfaces of noble metals and also evaluate the optimal conditions for the generation of a surface-enhanced Raman signal of absorbed species on a metallic substrate. All simulations were performed with a classical electrodynamics approach using the full set of Maxwells equations, which were solved with the three-dimensional finite element method (FEM). Two different classes of surfaces where modeled using fractals, representing diffusion limited aggregation growth dendritic structures, such as one on the surface of electrodes, and second one representing the sponge-like structure used to model surfaces of particles with high porosity, such as metal coated catalyst supports. The simulations depict the high inhomogeneity of an enhanced electromagnetic field as both a field enhancement and field attenuation near the surface. While the diffusion limited aggregation dendritical fractals enhanced the near-field electromagnetic field, the sponge fractals significantly reduced the local electromagnetic field intensity. Moreover, the fractal orders of the fractal objects did not significantly alter the total enhancement, and the distribution of a near-field enhancement was essentially invariant to the changes in the angle of an incoming laser beam.

  4. The superluminal velocities as the consequence of non-classical states of electromagnetic field

    NASA Astrophysics Data System (ADS)

    Veklenko, B. A.

    2017-06-01

    It was shown within the framework of conventional quantum electrodynamics, and without using perturbation theory, the presence of superluminal signals, transferring the information, while investigating the scattering of quantum electromagnetic field by excited atom. The superluminal signals are impossible in the theory of free fields, but their existence is predicted by the theory of interacting fields.

  5. [The effect of electromagnetic fields on living organisms: plants, birds and animals].

    PubMed

    Rochalska, Małgorzata

    2007-01-01

    Electromagnetic fields, constant and alternating, are a static element of the environment. They originate from both natural and man-made sources. Depending on the type of the field, its intensity and time of activity, they exert different effects on the natural world (plants and animals). Some animals utilize magnetic field of the earth for their own purposes.

  6. Effects of Extremely Low Frequency Electromagnetic Fields on ’Physarum polycephalum’.

    DTIC Science & Technology

    When the myxomycete Physarum polycephalum is exposed to sinusoidal (45, 60, 75 Hz) or modulated (76 Hz) electromagnetic fields, the mitotic cycle is...fields is deleterious for Physarum (or other organisms); it can be concluded, however, that these fields do significantly affect biological processes.

  7. Terahertz diffraction enhanced transparency probed in the near field

    NASA Astrophysics Data System (ADS)

    Halpin, Alexei; van Hoof, Niels; Bhattacharya, Arkabrata; Mennes, Christiaan; Gomez Rivas, Jaime

    2017-08-01

    Electromagnetically induced transparency in metamaterials allows to engineer structures which transmit narrow spectral ranges of radiation while exhibiting a large group index. Implementation of this phenomenon frequently calls for strong near-field coupling of bright (dipolar) resonances to dark (multipolar) resonances in the metamolecules comprising the metamaterials. The sharpness and contrast of the resulting transparency windows thus depends strongly on how closely these metamolecules can be placed to one another, placing constraints on fabrication capabilities. In this manuscript, we demonstrate that the reliance on near-field interaction strength can be relaxed, and the magnitude of the electromagnetic-induced transparency enhanced, by exploiting the long-range coupling between metamolecules in periodic lattices. By placing dolmen structures resonant at THz frequencies in a periodic lattice, we show a significant increase of the transparency window when the in-plane diffraction is tuned to the resonant frequency of the metamolecules, as confirmed by direct mapping of the THz near-field amplitude across a lattice of dolmens. Through the direct interrogation of the dark resonance in the near field, we show the interplay of near- and far-field couplings in optimizing the response of planar dolmen arrays via diffraction-enhanced transparency.

  8. Controlling electromagnetic fields using periodic structures: Gratings, metamaterials, and photonic crystals

    NASA Astrophysics Data System (ADS)

    Memarian, Mohammad

    This thesis presents novel devices and techniques that enable new methods for enhancement, concentration, refraction, shaping, collimation, and directive beaming of electromagnetic fields. These unprecedented methods to control electromagnetic fields are achieved by exploring and harnessing the unique wave-interactions in periodic gratings, metamaterials, and photonic crystals, with emphasis on Epsilon-Near-Zero (ENZ) metamaterials and zero-index media. The presented solutions impact a wide variety of applications ranging from microwave to optical frequencies. A discovery of dramatic radiation enhancement of an invisible array of sources next to a sub-wavelength periodic metal strip grating is reported, both theoretically and experimentally. The phenomenon is first systematically theorized by introducing the 'spectral impulse response' approach for the aperiodic excitation problem, followed by the 'spectral array factor' approach for designing the near-field of array of sources. Such radiation enhancement has applications in sensing, detection, and accurate measurement of distance. The shaping and collimation of radiation of a simple dipole source near or buried inside a general anisotropic ENZ half-space is then systematically studied using the Lorentz reciprocity method. Various elliptic and hyperbolic anisotropic ENZ media are considered, showing how the air-side radiation can be enhanced and shaped using certain ENZs. A novel device and technique is proposed for collecting, refracting and concentrating incident waves into an area of high power concentration, at extremely short distances. This flat low-profile light-concentrator comprises a hetero-junction of anisotropic ENZ metamaterials (hyperbolic or elliptic), and is realized with plasmonic layered media at optical frequencies. By harnessing an extremely oblique refraction process in ENZs, the light-concentrator significantly outperforms the size requirements of existing thick high curvature lenses, useful

  9. Electromagnetic contributions to single-molecule sensitivity in surface-enhanced Raman scattering

    NASA Astrophysics Data System (ADS)

    Xu, Hongxing; Aizpurua, Javier; Käll, Mikael; Apell, Peter

    2000-09-01

    We examine whether single molecule sensitivity in surface-enhanced Raman scattering (SERS) can be explained in the framework of classical electromagnetic theory. The influence of colloid particle shape and size, composition (Ag or Au) and interparticle separation distance on the wavelength-dependent SERS enhancement factor is reported. Our calculations indicate that the maximum enhancement factor achievable through electromagnetics is of the order 1011. This is obtained only under special circumstances, namely at interstitial sites between particles and at locations outside sharp surface protrusions. The comparative rarity of such sites, together with the extreme spatial localization of the enhancement they provide, can qualitatively explain why only very few surface sites seem to contribute to the measured signal in single-molecule SERS experiments. Enhancement factors of the order 1014-1015, which have been reported in recent experiments, are likely to involve additional enhancement mechanisms such as chemisorption induced resonance Raman effects.

  10. Simple and effective monitoring of the electromagnetic field in the smart cities arena

    NASA Astrophysics Data System (ADS)

    Ares-Pena, Francisco J.; Franceschetti, Giorgio; Iodice, Antonio; Salas-Sánchez, Aarón A.

    2016-08-01

    A simple and economical method for monitoring the electromagnetic field intensity in built-up areas is presented. The method is based on the measurement of the field level over a limited number of points at street level in the city and their transmission to an operative control center, where the field values all over the city are correctly interpolated in real time. Citizens might obtain these values at their sites, via Internet, or by connecting with a dedicated call center. Numerical evaluations of the electromagnetic field intensity via the new developed model and confirming experimental results are finally presented.

  11. Theory of weak scattering of stochastic electromagnetic fields from deterministic and random media

    SciTech Connect

    Tong Zhisong; Korotkova, Olga

    2010-09-15

    The theory of scattering of scalar stochastic fields from deterministic and random media is generalized to the electromagnetic domain under the first-order Born approximation. The analysis allows for determining the changes in spectrum, coherence, and polarization of electromagnetic fields produced on their propagation from the source to the scattering volume, interaction with the scatterer, and propagation from the scatterer to the far field. An example of scattering of a field produced by a {delta}-correlated partially polarized source and scattered from a {delta}-correlated medium is provided.

  12. Terahertz Electromagnetic Fields (0.106 THz) Do Not Induce Manifest Genomic Damage In Vitro

    PubMed Central

    Hintzsche, Henning; Jastrow, Christian; Kleine-Ostmann, Thomas; Kärst, Uwe; Schrader, Thorsten; Stopper, Helga

    2012-01-01

    Terahertz electromagnetic fields are non-ionizing electromagnetic fields in the frequency range from 0.1 to 10 THz. Potential applications of these electromagnetic fields include the whole body scanners, which currently apply millimeter waves just below the terahertz range, but future scanners will use higher frequencies in the terahertz range. These and other applications will bring along human exposure to these fields. Up to now, only a limited number of investigations on biological effects of terahertz electromagnetic fields have been performed. Therefore, research is strongly needed to enable reliable risk assessment. Cells were exposed for 2 h, 8 h, and 24 h with different power intensities ranging from 0.04 mW/cm2 to 2 mW/cm2, representing levels below, at, and above current safety limits. Genomic damage on the chromosomal level was measured as micronucleus formation. DNA strand breaks and alkali-labile sites were quantified with the comet assay. No DNA strand breaks or alkali-labile sites were observed as a consequence of exposure to terahertz electromagnetic fields in the comet assay. The fields did not cause chromosomal damage in the form of micronucleus induction. PMID:23029508

  13. Terahertz electromagnetic fields (0.106 THz) do not induce manifest genomic damage in vitro.

    PubMed

    Hintzsche, Henning; Jastrow, Christian; Kleine-Ostmann, Thomas; Kärst, Uwe; Schrader, Thorsten; Stopper, Helga

    2012-01-01

    Terahertz electromagnetic fields are non-ionizing electromagnetic fields in the frequency range from 0.1 to 10 THz. Potential applications of these electromagnetic fields include the whole body scanners, which currently apply millimeter waves just below the terahertz range, but future scanners will use higher frequencies in the terahertz range. These and other applications will bring along human exposure to these fields. Up to now, only a limited number of investigations on biological effects of terahertz electromagnetic fields have been performed. Therefore, research is strongly needed to enable reliable risk assessment.Cells were exposed for 2 h, 8 h, and 24 h with different power intensities ranging from 0.04 mW/cm(2) to 2 mW/cm(2), representing levels below, at, and above current safety limits. Genomic damage on the chromosomal level was measured as micronucleus formation. DNA strand breaks and alkali-labile sites were quantified with the comet assay. No DNA strand breaks or alkali-labile sites were observed as a consequence of exposure to terahertz electromagnetic fields in the comet assay. The fields did not cause chromosomal damage in the form of micronucleus induction.

  14. Abnormal responses of electronic pocket dosimeters caused by high frequency electromagnetic fields emitted from digital cellular telephones.

    PubMed

    Deji, Shizuhiko; Nishizawa, Kunihide

    2005-09-01

    High frequency electromagnetic fields emitted from digital cellular telephones (cell phones) occasionally cause abnormally high and erroneous indicated dose readings on electronic pocket dosimeters (EPDs). Electric field strength distribution around a cell phone transmitting 1.5 GHz band with a maximum power of 0.8 W was analyzed by using an isotropic probe with tri-axial dipole antennas. Five types of EPDs were exposed to the fields for 50 s under configurations relative to the cell phone. The electric field distribution expanded around the phone's antenna and had a maximum electric field strength of 36.5 +/- 0.3 V m(-1). The cell phone gave rise to erroneous indicated dose readings on four out of five EPDs. The maximum value of erroneous indicated dosage for 50 s reached 1,283 microSv, which was about 2.6% of the annual effective dose limit of 50 mSv. The electromagnetic susceptibility of the EPDs was higher in the sections where the semiconductor detectors or electric circuit boards were located. The distance required to prevent electromagnetic interference differed for each EPD and ranged from 2.0 to 21.0 cm from the cell phone. The electric and magnetic field immunity levels of the EPDs varied from 9.2 V m(-1) to greater than 37.6 V m(-1), and from 0.03 A m(-1) to greater than 0.51 A m(-1). The EPDs displayed erroneous dose readings during exposure but recovered their normal performance after the cell phone ceased transmitting. The electromagnetic immunity levels of the EPDs were either equal to or greater than the IEC-standard. The immunity levels should be enhanced greater than the IEC-standard from the standpoint of radiation protection. The simplest and most reliable measure to prevent potential malfunction is to prohibit the radiation workers from carrying cell phones to their workplace.

  15. Localized electromagnetic and weak gravitational fields in the source-free space.

    PubMed

    Borzdov, G N

    2001-03-01

    Localized electromagnetic and weak gravitational time-harmonic fields in the source-free space are treated using expansions in plane waves. The presented solutions describe fields having a very small (about several wavelengths) and clearly defined core region with maximum intensity of field oscillations. In a given Lorentz frame L, a set of the obtained exact time-harmonic solutions of the free-space homogeneous Maxwell equations consists of three subsets (storms, whirls, and tornados), for which time average energy flux is identically zero at all points, azimuthal and spiral, respectively. In any other Lorentz frame L', they will be observed as a kind of electromagnetic missile moving without dispersing at speed Velectromagnetic storms, whirls, tornados, and weak gravitational fields with similar properties are also presented. The properties of these fields are illustrated in graphic form.

  16. Radiation of electromagnetic waves by a dipole in an external uniform electrostatic field

    NASA Astrophysics Data System (ADS)

    Manaenkov, S. I.

    2017-01-01

    Exact solution for the electromagnetic field densities E and H of a dipole of uniformly accelerated point-charges with identical masses is discussed. It is shown that, for any fixed time t and a large distance R between the center of the dipole and the fieldpoint, | E| R -4, | H| R -5, while for large c| t| R, | E| | H| 1/ R as in spherical electromagnetic waves. Nevertheless, any irreversible radiation of electromagnetic waves is absent since the wave zone does not exist.

  17. Electromagnetic Near Field Measurements of Two Critical Assemblies

    SciTech Connect

    Goettee, Jeffrey David

    2015-11-03

    The reactors employed, Godiva IV and WSMR Fast Burst Reactor, are described first. Then the point reactor kinetics model, electromagnetic potential, and the measurement of kinetics quantities are successively discussed. In summary, reactor power produces measurable electric energy. The electric signal mimics power curve for prompt burst operations - features in logarithmic derivatives match. The electric signature should be dependent on the power and not the derivative; therefore, steady-state modes should be measurable.

  18. Study of the shielding performances of different materials regarding Electromagnetic Field Interference

    NASA Astrophysics Data System (ADS)

    Conecici, L. M.; Munteanu, C.; Purcar, I. M.

    2017-05-01

    This paper presents a computer-aided comparison of some of the most used electromagnetic shielding materials. Computer-aided design (CAD) model and the computer aided engineering (CAE) simulation technologies are used for the analysis of the electromagnetic field shielding performances of each material individually and a comparison will be established. The main topic of this comparison is to establish a proper shielding material for ElectroMagnetic Interference (EMI) sources. A three-dimensional (CAD) model of the circuit breaker coil designed in PTC Creo Elements v.18.1 environment was analyzed in Ansoft Maxwell v.15 environment in order to compute the electromagnetic field distribution. The residual (EMI) values are compared to one another and the best shielding material will be presented for this circumstances.

  19. Environmental impact of the use of radiofrequency electromagnetic fields in physiotherapeutic treatment.

    PubMed

    Gryz, Krzysztof; Karpowicz, Jolanta

    2014-01-01

    Electromagnetic fields used in physiotherapeutic treatment affect not only patients, but also physiotherapists, patients not undergoing treatment and electronic medical equipment. The aim of the work was to study the parameters of the electromagnetic fields of physiotherapeutic devices with respect to requirements regarding the protection of electronic devices, including medical implants, against electromagnetic intererence, and the protection of the general public (patients not undergoing treatment and bystanders), as well as medical personnel, against the health hazards caused by electromagnetic exposure. The spatial distribution of electric and magnetic field strength was investigated near 3 capacitive short-wave and 3 long-wave diathermies and 3 ultrasound therapy units, as along with the capacitive electric currents caused by electromagnetic field interaction in the upper limbs of the physiotherapists operating these devices. The physiotherapists' exposure to electromagnetic fields depends on the spatial organisation of the workspace and their location during treatment. Electric fields able to interfere with the function of electronic medical implants and in whic anyone not undergoing treatment should not be present were measured up to 150-200 cm away from active applicators of short-wave diathermy, and up to 40-45 cm away from long-wave diathermy ones. Electric fields in which workers should not be present were measured up to 30-40 cm away from the applicators and cables of active short-wave diathermy devices. A capacitive electric current with a strength exceeding many times the international recommendations regarding workers protection was measured in the wrist while touching applicators and cables of active short-wave diathermy devices. The strongest environmental electromagnetic hazards occur near short-wave diathermy devices, and to a lesser degree near long-wave diathermy devices, but were not found near ultrasound therapy units.

  20. Pulsed electromagnetic fields after rotator cuff repair: a randomized, controlled study.

    PubMed

    Osti, Leonardo; Buono, Angelo Del; Maffulli, Nicola

    2015-03-01

    The current study tested the hypothesis that the use of pulsed electromagnetic fields after rotator cuff repair is effective in the short term as an adjuvant treatment to reduce local inflammation, postoperative joint swelling, and recovery time, as well as to induce pain relief. Sixty-six patients who underwent shoulder arthroscopy for repair of small to medium rotator cuff tears were randomly divided into 2 groups with a block randomization procedure. Thirty-two patients underwent arthroscopic rotator cuff repair and application of pulsed electromagnetic fields postoperatively; 34 patients underwent rotator cuff repair and placebo treatment (placebo group). All patients had the same postoperative rehabilitation protocol. At 3 months from the index procedure, visual analog scale, range of motion, and University of California at Los Angeles and Constant scores were significantly better in the pulsed electromagnetic fields group than in the placebo group (P<.05). Three patients in the pulsed electromagnetic fields group and 7 patients in the placebo group had mild to moderate capsulitis (P=.2). Severe capsulitis occurred in 1 patient in the pulsed electromagnetic fields group and 2 patients in the placebo group (P=.6). At the last follow-up (minimum, 2 years), clinical and functional outcomes were further improved in both groups, with no significant intergroup differences. Application of pulsed electromagnetic fields after rotator cuff repair is safe and reduces postoperative pain, analgesic use, and stiffness in the short term. At 2 years, no difference was seen in outcomes in patients who did or did not undergo treatment with pulsed electromagnetic fields. Copyright 2015, SLACK Incorporated.

  1. Electromagnetic instability in plasmas heated by a laser field.

    PubMed

    Bendib, A; Bendib-Kalache, K; Cros, B; Deutsch, C; Maynard, G

    2017-02-01

    Electromagnetic instability is investigated in homogeneous plasmas heated by a laser wave in the range α=v_{0}^{2}/v_{t}^{2}≤2, where v_{0} is the electron quiver velocity and v_{t} is the thermal velocity. The anisotropic electron distribution function that drives unstable quasistatic electromagnetic modes is calculated numerically with the Vlasov-Landau equation in the high ion charge number approximation. A dispersion relation of electromagnetic waves which accounts for further nonlinear terms on v_{0}^{2} from previous results is derived. In typical simulation with ion charge number Z=13, a temperature T=5keV, a density n=9.8×10^{20}cm^{-3}, and a laser wavelength λ_{laser}=1.06μm, growth rates larger than 10^{12}s^{-1} in the quasicollisionless wave-number range were found for α≥1. In the same physical conditions and in the mildly collisional range a growth rate about 10^{11}s^{-1} was also obtained. The extent of the growth wave-number region increases significantly with increasing α.

  2. Electromagnetic instability in plasmas heated by a laser field

    NASA Astrophysics Data System (ADS)

    Bendib, A.; Bendib-Kalache, K.; Cros, B.; Deutsch, C.; Maynard, G.

    2017-02-01

    Electromagnetic instability is investigated in homogeneous plasmas heated by a laser wave in the range α =v02/vt2≤2 , where v0 is the electron quiver velocity and vt is the thermal velocity. The anisotropic electron distribution function that drives unstable quasistatic electromagnetic modes is calculated numerically with the Vlasov-Landau equation in the high ion charge number approximation. A dispersion relation of electromagnetic waves which accounts for further nonlinear terms on v02 from previous results is derived. In typical simulation with ion charge number Z =13 , a temperature T =5 keV , a density n =9.8 ×1020c m-3 , and a laser wavelength λlaser=1.06 μ m , growth rates larger than 1012s-1 in the quasicollisionless wave-number range were found for α ≥1 . In the same physical conditions and in the mildly collisional range a growth rate about 1011s-1 was also obtained. The extent of the growth wave-number region increases significantly with increasing α .

  3. Design considerations for near-field enhancement in optical antennas

    NASA Astrophysics Data System (ADS)

    Fernández-García, Roberto; Sonnefraud, Yannick; Fernández-Domínguez, Antonio I.; Giannini, Vincenzo; Maier, Stefan A.

    2014-01-01

    Nanoantennas for visible and infrared radiation can strongly enhance the interaction of light with matter by their ability to localise electromagnetic fields on nanometric scales. This allows for the engineering of the absorption and radiation capabilities of nanoemitters, such as dye molecules or quantum dots. In this article, we discuss the main parameters influencing the near-field enhancement provided by dimer-type nanoantennas, the configuration most thoroughly studied in the literature. To facilitate the design of structures, we analyse the influence of the substrate, adhesion layers and a reflective metal underlayer, as well as their arrangement in a periodic fashion. We also highlight the factors which increase the damping of the localised plasmonic modes and the spectral differences between far and near-field resonances.

  4. [Reaction of the endocrine system to continuous and intermittent electromagnetic fields].

    PubMed

    Zagorskaia, E A

    1989-01-01

    This paper reviews Soviet and foreign data about the effects of low frequency electromagnetic fields of continuous and intermittent generation on the endocrine system of animals and humans. It has been shown that the pituitary-adrenal, pituitary-thyroid and reproductive systems are sensitive to these effects. It is postulated that the endocrine responses to electromagnetic effects are similar to the general adaptive reactions to various pathophysiological exposures.

  5. Electromagnetic Imaging of CO2 Sequestration at an Enhanced-Oil-Recovery Site

    SciTech Connect

    Kirkendall, B; Roberts, J

    2004-02-17

    The two year LDRD-ER-089 project Electromagnetic Imaging of CO{sub 2} Sequestration at an Enhanced-Oil-Recovery Site used a dual track approach to imaging and interpreting the effectiveness and migration of CO2 injection at an enhanced oil recovery site. Both field data and laboratory data were used together to aid in the interpretation and understanding of CO{sub 2} flow in a heavily fracture enhanced oil recovery site. In particular, project highlights include; {lg_bullet} The development of a low-noise digital field system to measure the EM induction response to CO{sub 2} in a variety of field conditions. Central to this system is a low-noise induction receiver antenna that can measure the low-energy response of the CO{sub 2}. This system has consistently measured a shallow pseudo-miscible CO{sub 2} flood at source frequencies between 2.0 kHz and 10 kHz. In addition, the existing and added oil and brine in the formation have also been characterized. {lg_bullet} Comparisons of cross-well images with induction logs acquired before drilling suggest the EM induction resolution for CO2 imaging is equivalent with applications to waterflood imaging completed at LLNL. {lg_bullet} The development and use of laboratory equipment to conduct fluid and gas time-lapsed injection studies of core samples using fluids acquired in the field. Measurements of the resistivity during this injection process and the ability to make instantaneous measurements of the frequency response provide a unique dataset for interpretation. {lg_bullet} The development of an optimum finite difference grid spacing that allows for stable inversions at different frequencies. {lg_bullet} The use of time-lapse field images to show the change of electrical conductivity in the field scales to the laboratory results. Using this result, we can approximate an interpretation of field images based on the rate-of-change of the laboratory results. {lg_bullet} The application of Q-domain processing is not

  6. In vitro electromagnetic stimulation to enhance cell proliferation in extracellular matrix constructs with and without metallic nanoparticles.

    PubMed

    Grant, Daniel N; Cozad, Matthew J; Grant, David A; White, Richard A; Grant, Sheila A

    2015-11-01

    Extremely low frequency electromagnetic fields (ELF-EMFs) can induce beneficial effects including enhanced protein synthesis and cell proliferation on healing bone and skin wounds. This study investigated the effects of ELF-EMFs on acellular tissue constructs with and without gold nanoparticles (AuNPs) to determine if cell proliferation could be increase and thus provide an enhanced mechanism for in vitro cell seeding on tissue engineered constructs. Different sized AuNPs, 20 and 100 nm, were conjugated to acellular porcine tissue, seeded with L929 murine fibroblasts and exposed to a continuous 12 gauss, 60 Hz electromagnetic field for 2 hours each day up to 10 days. Scanning electron microscopy and cell culture assays were performed to ascertain cell proliferation and viability before and after exposure. Results indicate the ELF-EMF stimulation significantly increased cell proliferation. The presence of AuNPs did not boost the stimulatory effects, but they did demonstrated higher rates of proliferation from day 3 to day 10. In addition, unstimulated 100 nm AuNPs constructs resulted in significant increases in proliferation as compared to unstimulated crosslinked constructs. In conclusion, ELF-EMF stimulation enhanced cellular proliferation and while the presence of AuNPs did not significantly enhance this effect, AuNPs resulted in increased proliferation rates from day 3 to day 10.

  7. Gold nanoparticle dimer plasmonics: finite element method calculations of the electromagnetic enhancement to surface-enhanced Raman spectroscopy.

    PubMed

    McMahon, Jeffrey M; Henry, Anne-Isabelle; Wustholz, Kristin L; Natan, Michael J; Freeman, R Griffith; Van Duyne, Richard P; Schatz, George C

    2009-08-01

    Finite element method calculations were carried out to determine extinction spectra and the electromagnetic (EM) contributions to surface-enhanced Raman spectroscopy (SERS) for 90-nm Au nanoparticle dimers modeled after experimental nanotags. The calculations revealed that the EM properties depend significantly on the junction region, specifically the distance between the nanoparticles for spacings of less than 1 nm. For extinction spectra, spacings below 1 nm lead to maxima that are strongly red-shifted from the 600-nm plasmon maximum associated with an isolated nanoparticle. This result agrees qualitatively well with experimental transmission electron microscopy images and localized surface plasmon resonance spectra that are also presented. The calculations further revealed that spacings below 0.5 nm, and especially a slight fusing of the nanoparticles to give tiny crevices, leads to EM enhancements of 10(10) or greater. Assuming a uniform coating of SERS molecules around both nanoparticles, we determined that regardless of the separation, the highest EM fields always dominate the SERS signal. In addition, we determined that for small separations less than 3% of the molecules always contribute to greater than 90% of the signal.

  8. Radiation enhanced efficiency of combined electromagnetic hyperthermia and chemotherapy of lung carcinoma using cisplatin functionalized magnetic nanoparticles.

    PubMed

    Babincová, M; Kontrisova, K; Durdík, S; Bergemann, C; Sourivong, P

    2014-02-01

    The effect of trimodality treatment consisting of hyperthermia, cisplatin and radiation was investigated in two non-small lung carcinoma cell lines with different sensitivities to cisplatin. Hyperthermia treatment was performed using heat released via Neél and Brown relaxation of magnetic nanoparticles in an alternating magnetic field. Radiation with dose 1.5 Gy was performed after 15 min electromagnetic hyperthermia and cisplatin treatment. Electromagnetic hyperthermia enhanced cisplatin-induced radiosensitization in both the cisplatin-sensitive H460 (viability 11.2 +/- 1.8 %) and cisplatin-resistant A549 (viability 14.5 +/- 2.3 %) lung carcinoma cell line. Proposed nanotechnology based trimodality cancer treatment may have therefore important clinical applications.

  9. Differentiation of osteoprogenitor cells is induced by high-frequency pulsed electromagnetic fields.

    PubMed

    Teven, Chad M; Greives, Matthew; Natale, Ryan B; Su, Yuxi; Luo, Qing; He, Bai-Cheng; Shenaq, Deana; He, Tong-Chuan; Reid, Russell R

    2012-03-01

    Craniofacial defect repair is often limited by a finite supply of available autologous tissue (ie, bone) and less than ideal alternatives. Therefore, other methods to produce bony healing must be explored. Several studies have demonstrated that low-frequency pulsed electromagnetic field (PEMF) stimulation (ie, 5-30 Hz) of osteoblasts enhances bone formation. The current study was designed to investigate whether a Food and Drug Administration-approved, high-frequency PEMF-emitting device is capable of inducing osteogenic differentiation of osteoprogenitor cells. Osteoprogenitor cells (commercially available C3H10T1/2 and mouse calvarial) in complete Dulbecco modified Eagle medium were continuously exposed to PEMF stimulation delivered by the ActiPatch at a frequency of 27.1 MHz. Markers of cellular proliferation and early, intermediate, and terminal osteogenic differentiation were measured and compared with unstimulated controls. All experiments were performed in triplicate. High-frequency PEMF stimulation increases alkaline phosphatase activity in both cell lines. In addition, high-frequency PEMF stimulation augments osteopontin and osteocalcin expression as well as mineral nodule formation in C3H10T1/2 cells, indicating late and terminal osteogenic differentiation, respectively. Cellular proliferation, however, was unaffected by high-frequency PEMF stimulation. Mechanistically, high-frequency PEMF-stimulated osteogenic differentiation is associated with elevated mRNA expression levels of osteogenic bone morphogenetic proteins in C3H10T1/2 cells. Our findings suggest that high-frequency PEMF stimulation of osteoprogenitor cells may be explored as an effective tissue engineering strategy to treat critical-size osseous defects of the craniofacial and axial skeleton. ALP, alkaline phosphatase; BMP, bone morphogenetic protein; ERK-1, extracellular signal-regulated kinase 1; iCALs, immortalized calvarial cells; IHC, immunohistochemical; MAP, mitogen-activated protein

  10. Classical electromagnetic fields from quantum sources in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Holliday, Robert; McCarty, Ryan; Peroutka, Balthazar; Tuchin, Kirill

    2017-01-01

    Electromagnetic fields are generated in high energy nuclear collisions by spectator valence protons. These fields are traditionally computed by integrating the Maxwell equations with point sources. One might expect that such an approach is valid at distances much larger than the proton size and thus such a classical approach should work well for almost the entire interaction region in the case of heavy nuclei. We argue that, in fact, the contrary is true: due to the quantum diffusion of the proton wave function, the classical approximation breaks down at distances of the order of the system size. We compute the electromagnetic field created by a charged particle described initially as a Gaussian wave packet of width 1 fm and evolving in vacuum according to the Klein-Gordon equation. We completely neglect the medium effects. We show that the dynamics, magnitude and even sign of the electromagnetic field created by classical and quantum sources are different.

  11. On the determination of the electromagnetic field upon scattering by a small inhomogeneous spherical object

    SciTech Connect

    Shalashov, A. G. Gospodchikov, E. D.

    2016-10-15

    An efficient and fairly simple method of solving the problem of the incidence of a plane electromagnetic wave on an inhomogeneous object with specified spherically symmetric distributions of its electric permittivity and magnetic permeability is presented. The fields inside the object and the integrated scattering and absorption cross sections are found by assuming the object to be small compared to the vacuum wavelength. Since no constraints are imposed on the scales of the fields inside the object, the method is suitable for investigating complex cases, including those associated with the local amplification and absorption of the electromagnetic field in inhomogeneous resonant media.

  12. All-dielectric nanostructures for low-loss field enhanced spectroscopy and imaging (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Yano, Taka-aki; Tsuchimoto, Yuta; Hayashi, Tomohiro; Hara, Masahiko

    2016-09-01

    Dielectric nanostructures with high refractive index and low optical loss have attracted considerable attention as an alternative to plasmonic nanostructures. We experimentally demonstrated to control the visible electromagnetic resonances of Si-based core-shell nanostructures by thermally varying the core-shell ratio. We also found a Fano resonance which was generated by the interference between the electric and magnetic dipole moments excited in the core-shell nanostructures. The all-dielectric nanostructures realized low energy loss and high electromagnetic field enhancement comparable with that exhibited by plasmonic nanostructures. These unique optical properties would enable us to demonstrate effective field-enhanced spectroscopy and imaging with low heat generation.

  13. The nonextensive parameter for nonequilibrium electron gas in an electromagnetic field

    SciTech Connect

    Yu, Haining; Du, Jiulin

    2014-11-15

    The nonextensive parameter for nonequilibrium electron gas of the plasma in an electromagnetic field is studied. We exactly obtained an expression of the q-parameter based on Boltzmann kinetic theories for plasmas, where Coulombian interactions and Lorentz forces play dominant roles. We show that the q-parameter different from unity is related by an equation to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the gas. The effect of the magnetic field on the q-parameter depends on the overall bulk velocity. Thus the q-parameter for the electron gas in an electromagnetic field represents the nonequilibrium nature or nonisothermal configurations of the plasma with electromagnetic interactions. - Highlights: • An expression of the q-parameter is obtained for nonequilibrium plasma with electromagnetic interactions. • The q-parameter is related to temperature gradient, electric field strength, magnetic induction as well as overall bulk velocity of the plasma. • The q-parameter represents the nonequilibrium nature of the complex plasma with electromagnetic interactions.

  14. [Proposal for magnetic/electromagnetic fields protection norms on national level].

    PubMed

    Dordević, Drago; Raković, Dejan

    2008-01-01

    The modern life is not possible without application of magnetic/electromagnetic fields, which can be both helpful and harmful for human body. The non-ionizing radiation, especially magnetic/electromagnetic fields of all frequencies (0-300 GHz), can have many harmful effects on the human health that is confirmed by numerous epidemiological studies, studies with volunteers, animal studies, and in vitro studies. Proposal for magnetic/electromagnetic fields protection norms on national level based on the WHO Program for Environment, International Commission on Non-Ionizing Radiation Protection (ICNIRP)], and WHO International EMF Project. Protection from harmful effects of the magnetic/electromagnetic fields is still a great problem in many countries of modern society--huge costs, impaired quality of life, and more important, damage to the human health. Numerous data and publications of harmful effects of the magnetic/electromagnetic fields represents one's country basic necessary documentation for making decisions and law documents for protection norms on national level concerning the health maintenance according to the ICNIRP normatives.

  15. Influence of extremely low frequency electromagnetic fields on growth performance, innate immune response, biochemical parameters and disease resistance in rainbow trout, Oncorhynchus mykiss.

    PubMed

    Nofouzi, Katayoon; Sheikhzadeh, Najmeh; Mohamad-Zadeh Jassur, Davood; Ashrafi-Helan, Javad

    2015-06-01

    The effects of extremely low frequency electromagnetic fields on rainbow trout growth performance, innate immunity and biochemical parameters were studied. Rainbow trout (17-18 g) were exposed to electromagnetic fields (15 Hz) at 0.01, 0.1, 0.5, 5 and 50 µT, for 1 h daily over period of 60 days. Growth performance of fish improved in different treatment groups, especially at 0.1, 0.5, 5 and 50 µT. Immunological parameters, specifically hemagglutinating titer, total antiprotease and α1-antiprotease levels in treatment groups, were also enhanced. Total protein and globulin contents in the serum of fish exposed to 0.1, 0.5, 5 and 50 µT were significantly higher than those in the control group. No significant differences were found in serum enzyme activities, namely aspartate aminotransferase and alanine aminotransferase of fish in all treatment groups. Conversely, alkaline phosphatase level decreased in fish exposed to 0.01 and 50 µT electromagnetic fields. Meanwhile, electromagnetic induction at 0.1, 0.5, 5 and 50 µT enhanced fish protection against Yersinia ruckeri. These results indicated that these specific electromagnetic fields had possible effects on growth performance, nonspecific immunity and disease resistance of rainbow trout.

  16. Theoretical study of electromagnetic electron cyclotron waves in the presence of AC field in Uranian magnetosphere

    NASA Astrophysics Data System (ADS)

    Pandey, R. S.; Kaur, Rajbir

    2015-10-01

    Electromagnetic electron cyclotron (EMEC) waves with temperature anisotropy in the magnetosphere of Uranus have been studied in present work. EMEC waves are investigated using method of characteristic solution by kinetic approach, in presence of AC field. In 1986, Voyager 2 encounter with Uranus revealed that magnetosphere of Uranus exhibit non-Maxwellian high-energy tail distribution. So, the dispersion relation, real frequency and growth rate are evaluated using Lorentzian Kappa distribution function. Effect of temperature anisotropy, AC frequency and number density of particles is found. The study is also extended to oblique propagation of EMEC waves in presence and absence of AC field. Through comprehensive mathematical analysis it is found that when EMEC wave propagates parallel to intrinsic magnetic field of Uranus, its growth is more enhanced than in case of oblique propagation. Results are also discussed in context to magnetosphere of Earth and also gives theoretical explanation to existence of high energetic particles observed by Voyager 2 in the magnetosphere of Uranus. The results can present a further insight into the nature of electron-cyclotron instability condition for the whistler mode waves in the outer radiation belts of Uranus or other space plasmas.

  17. Pro-oxidant effects of extremely low frequency electromagnetic fields in the land snail Helix aspersa.

    PubMed

    Regoli, Francesco; Gorbi, Stefania; Machella, Nicola; Tedesco, Sara; Benedetti, Maura; Bocchetti, Raffaella; Notti, Alessandra; Fattorini, Daniele; Piva, Francesco; Principato, Giovanni

    2005-12-15

    Pro-oxidant effects of extremely low frequency (ELF) 50-Hz magnetic fields were investigated in the land snail Helix aspersa exposed both in short-term laboratory treatments and under field conditions by maintaining the organisms in the proximity of a power line for up to 2 months. Oxidative perturbations were investigated as individual antioxidants (catalase, glutathione reductase, glutathione S-transferases, and total glutathione) and total scavenging capacity toward peroxyl radicals and hydroxyl radicals. Accumulation of lipid peroxidation products, destabilization of lysosomal membranes, and loss of DNA integrity were also evaluated as markers of cell damage. The overall results indicated an oxidative challenge caused by ELF magnetic fields with particularly prompt and sensitive responses for catalase, glutathione reductase, and the overall capability to neutralize peroxyl radicals. Cell injuries occurred to different extents according to duration and intensity of electromagnetic exposure and confirmed complex cause-effect relationships between pro-oxidant factors, efficiency of antioxidant defenses, and the onset of oxidative toxicity. This study highlights the importance of a multimarker approach for detecting a wide panel of biological responses, the necessity of investigating the long-term effects of early oxidative responses, and the role of ELF in enhancing susceptibility to other forms of pathologies or diseases.

  18. Interplay between Rashba interaction and electromagnetic field in the edge states of a two-dimensional topological insulator

    NASA Astrophysics Data System (ADS)

    Dolcini, Fabrizio

    2017-02-01

    The effects of Rashba interaction and electromagnetic field on the edge states of a two-dimensional topological insulator are investigated in a nonperturbative way. We show that the electron dynamics is equivalent to a problem of massless Dirac fermions propagating with an inhomogeneous velocity, enhanced by the Rashba profile with respect to the bare Fermi value vF. Despite the inelastic and time-reversal breaking processes induced by the electromagnetic field, no backscattering occurs without interaction. The photoexcited electron densities are explicitly obtained in terms of the electric field and the Rashba interaction, and are shown to fulfill generalized chiral anomaly equations. The case of a Gaussian electromagnetic pulse is analyzed in detail. When the photoexcitation occurs far from the Rashba region, the latter effectively acts as a "superluminal gate" boosting the photoexcited wave packet outside the light-cone determined by vF. In contrast, for an electric pulse overlapping the Rashba region, the emerging wave packets are squeezed in a manner that depends on the overlap area. The electron-electron interaction effects are also discussed, for both intraspin and interspin density-density coupling. The results suggest that Rashba interaction, often considered as an unwanted disorder effect, may be exploited to tailor the shape and the propagation time of photoexcited spin-polarized wave packets.

  19. Detection of buried targets using a new enhanced very early time electromagnetic (VETEM) prototype system

    USGS Publications Warehouse

    Cui, T.J.; Chew, W.C.; Aydiner, A.A.; Wright, D.L.; Smith, D.V.

    2001-01-01

    In this paper, numerical simulations of a new enhanced very early time electromagnetic (VETEM) prototype system are presented, where a horizontal transmitting loop and two horizontal receiving loops are used to detect buried targets, in which three loops share the same axis and the transmitter is located at the center of receivers. In the new VETEM system, the difference of signals from two receivers is taken to eliminate strong direct-signals from the transmitter and background clutter and furthermore to obtain a better SNR for buried targets. Because strong coupling exists between the transmitter and receivers, accurate analysis of the three-loop antenna system is required, for which a loop-tree basis function method has been utilized to overcome the low-frequency breakdown problem. In the analysis of scattering problem from buried targets, a conjugate gradient (CG) method with fast Fourier transform (FFT) is applied to solve the electric field integral equation. However, the convergence of such CG-FFT algorithm is extremely slow at very low frequencies. In order to increase the convergence rate, a frequency-hopping approach has been used. Finally, the primary, coupling, reflected, and scattered magnetic fields are evaluated at receiving loops to calculate the output electric current. Numerous simulation results are given to interpret the new VETEM system. Comparing with other single-transmitter-receiver systems, the new VETEM has better SNR and ability to reduce the clutter.

  20. Exact Electromagnetic Fields Produced by a Finite Wire with Constant Current

    ERIC Educational Resources Information Center

    Jimenez, J. L.; Campos, I.; Aquino, N.

    2008-01-01

    We solve exactly the problem of calculating the electromagnetic fields produced by a finite wire with a constant current, by using two methods: retarded potentials and Jefimenko's formalism. One result in this particular case is that the usual Biot-Savart law of magnetostatics gives the correct magnetic field of the problem. We also show…

  1. Public health risk from ELF (electromagnetic fields) exposure -- can it be assessed

    SciTech Connect

    Aldrich, T.E.; Easterly, C.E.

    1988-01-01

    Extremely low frequency electromagnetic fields (ELF) are a ubiquitous environmental agent. There are persistent indications that these fields have biologic activity, and consequently, there may be a deleterious component to their action. Epidemiologic researchers of ELF face several methodological obstacles, and quantitative risk assessment is in a quandary. Simply stated there is a need for more data---especially with regard to exposure assessment.

  2. Quantum analysis of fluctuations of electromagnetic fields in heavy-ion collisions

    NASA Astrophysics Data System (ADS)

    Zakharov, B. G.

    2017-06-01

    We perform quantum calculations of fluctuations of the electromagnetic fields in AA collisions at RHIC and LHC energies. The analysis is based on the fluctuation-dissipation theorem. We find that in the quantum picture the field fluctuations are very small. They turn out to be much smaller than the predictions of the classical Monte Carlo simulation with the Woods-Saxon nuclear density.

  3. Exact Electromagnetic Fields Produced by a Finite Wire with Constant Current

    ERIC Educational Resources Information Center

    Jimenez, J. L.; Campos, I.; Aquino, N.

    2008-01-01

    We solve exactly the problem of calculating the electromagnetic fields produced by a finite wire with a constant current, by using two methods: retarded potentials and Jefimenko's formalism. One result in this particular case is that the usual Biot-Savart law of magnetostatics gives the correct magnetic field of the problem. We also show…

  4. Molecular based magnets comprising vanadium tetracyanoethylene complexes for shielding electromagnetic fields

    DOEpatents

    Epstein, Arthur J.; Morin, Brian G.

    1998-01-01

    The invention presents a vanadium tetracyanoethylene solvent complex for electromagnetic field shielding, and a method for blocking low frequency and magnetic fields using these vanadium tetracyanoethylene compositions. The compositions of the invention can be produced at ambient temperature and are light weight, low density and flexible. The materials of the present invention are useful as magnetic shields to block low frequency fields and static fields, and for use in cores in transformers and motors.

  5. Molecular based magnets comprising vanadium tetracyanoethylene complexes for shielding electromagnetic fields

    DOEpatents

    Epstein, A.J.; Morin, B.G.

    1998-10-13

    The invention presents a vanadium tetracyanoethylene solvent complex for electromagnetic field shielding, and a method for blocking low frequency and magnetic fields using these vanadium tetracyanoethylene compositions. The compositions of the invention can be produced at ambient temperature and are light weight, low density and flexible. The materials of the present invention are useful as magnetic shields to block low frequency fields and static fields, and for use in cores in transformers and motors. 21 figs.

  6. Magnetic field instability of a plasma in a beam of electromagnetic radiation

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    1980-04-01

    A beam of electromagnetic radiation can generate magnetic fields in plasmas. It is shown that those fields grow significantly when the incident radiation is sufficiently strong. We obtain expressions for the characteristic time of the growth of the fields as well as for their spatial distribution and point out a possible mechanism, which can lead to the formation of a quasi-stationary state. The maximum value of the magnetic field strength is estimated.

  7. Low-frequency pulsed electromagnetic fields significantly improve time of closure and proliferation of human tendon fibroblasts

    PubMed Central

    2014-01-01

    Background The promotion of the healing process following musculoskeletal injuries comprises growth factor signalling, migration, proliferation and apoptosis of cells. If these processes could be modulated, the healing of tendon tissue may be markedly enhanced. Here, we report the use of the Somagen™ device, which is certified for medical use according to European laws. It generates low-frequency pulsed electromagnetic fields that trigger effects of a nature that are yet to be determined. Methods A 1.5-cm wide, linear scrape was introduced into patellar tendon fibroblast cultures (N = 5 donors). Treatment was carried out every second day. The regimen was applied three times in total with 30 minutes comprising pulsed electromagnetic field packages with two fundamental frequencies (10 minutes of 33 Hz, 20 minutes of 7.8 Hz). Control cells remained untreated. All samples were analyzed for gap closure time, proliferation and apoptosis one week after induction of the scrape wound. Results The mean time for bridging the gap in the nontreated cells was 5.05 ± 0.33 days, and in treated cells, it took 3.35 ± 0.38 days (P <0.001). For cell cultures with scrape wounds, a mean value for BrdU incorporation of OD = 0.70 ± 0.16 was found. Whereas low-frequency pulsed electromagnetic fields treated samples showed OD = 1.58 ± 0.24 (P <0.001). However, the percentage of apoptotic cells did not differ between the two groups. Conclusions Our data demonstrate that low-frequency pulsed electromagnetic fields emitted by the Somagen™ device influences the in vitro wound healing of patellar tendon fibroblasts and, therefore, possibly increases wound healing potential. PMID:24996421

  8. Low-frequency pulsed electromagnetic fields significantly improve time of closure and proliferation of human tendon fibroblasts.

    PubMed

    Seeliger, Claudine; Falldorf, Karsten; Sachtleben, Jens; van Griensven, Martijn

    2014-07-05

    The promotion of the healing process following musculoskeletal injuries comprises growth factor signalling, migration, proliferation and apoptosis of cells. If these processes could be modulated, the healing of tendon tissue may be markedly enhanced. Here, we report the use of the Somagen™ device, which is certified for medical use according to European laws. It generates low-frequency pulsed electromagnetic fields that trigger effects of a nature that are yet to be determined. A 1.5-cm wide, linear scrape was introduced into patellar tendon fibroblast cultures (N = 5 donors). Treatment was carried out every second day. The regimen was applied three times in total with 30 minutes comprising pulsed electromagnetic field packages with two fundamental frequencies (10 minutes of 33 Hz, 20 minutes of 7.8 Hz). Control cells remained untreated. All samples were analyzed for gap closure time, proliferation and apoptosis one week after induction of the scrape wound. The mean time for bridging the gap in the nontreated cells was 5.05 ± 0.33 days, and in treated cells, it took 3.35 ± 0.38 days (P <0.001). For cell cultures with scrape wounds, a mean value for BrdU incorporation of OD = 0.70 ± 0.16 was found. Whereas low-frequency pulsed electromagnetic fields treated samples showed OD = 1.58 ± 0.24 (P <0.001). However, the percentage of apoptotic cells did not differ between the two groups. Our data demonstrate that low-frequency pulsed electromagnetic fields emitted by the Somagen™ device influences the in vitro wound healing of patellar tendon fibroblasts and, therefore, possibly increases wound healing potential.

  9. Effects of pulsed electromagnetic fields on cognitive processes - a pilot study on pulsed field interference with cognitive regeneration.

    PubMed

    Maier, R; Greter, S-E; Maier, N

    2004-07-01

    Due to the ubiquitous use of cellular phones much has been speculated on secondary effects of electromagnetic irradiation emitted by those. Additionally, several studies have reported vegetative alterations as well as effects on the neuronal and molecular levels in humans. Here, using a psycho-physiological test paradigm, we examined effects of exposure to pulsed electromagnetic fields on cognitive performance. In 11 volunteers, we tested cognitive processing under field exposure (GSM standard) and under field-free conditions. To examine the hypothesized effect of pulsed fields, we applied an auditory discrimination task and determined the participant's current 'Order Threshold' value. Following a first test cycle, the volunteers had to relax for 50 min while being, or not, exposed to pulsed electromagnetic fields. Subsequently, the test was repeated. Data acquired before and after the resting phase were compared from both experimental conditions. We found that nine of the 11 test participants (81.8%) showed worse results in their auditory discrimination performance upon field exposure as compared with control conditions. Group data comparison revealed a statistical significance of P = 0.0105. We could show that the participants' cognitive performance was impaired after exposure to pulsed electromagnetic fields. With regard to this finding, we recommend that the use of cellular phones should be restricted generally and in particular in respect of physical hazard of high-risk groups, e.g. elderly, children and ill people.

  10. Quantitative evaluation of electromagnetic enhancement in surface-enhanced resonance Raman scattering from plasmonic properties and morphologies of individual Ag nanostructures

    NASA Astrophysics Data System (ADS)

    Yoshida, Ken-Ichi; Itoh, Tamitake; Tamaru, Hiroharu; Biju, Vasudevanpillai; Ishikawa, Mitsuru; Ozaki, Yukihiro

    2010-03-01

    The electromagnetic (EM) enhancement in surface-enhanced resonance Raman scattering (SERRS) is quantitatively evaluated for rhodamine molecules adsorbed on Ag nanostructures. Polarization dependence of the plasma resonance (plasmon resonance) and the SERRS spectra from single isolated Ag nanostructures was evaluated to determine one-to-one relationship between optical anisotropy of plasma resonance, that of SERRS, and the morphology of the nanostructures. Experimental observations were compared with finite-difference time-domain calculations of the EM field induced by plasma resonance using individual morphology of the nanostructures. The experimental enhancement factor of SERRS ˜109 was consistent with that of the calculations within a factor of ˜2 for three excitation wavelengths. We conclusively fortify the indispensible importance of SERRS-EM theory with our results to design metal nanostructures generating strong EM enhancement.

  11. Influence of electromagnetic field intensity on the metastable zone width of CaCO3 crystallization in circulating water

    NASA Astrophysics Data System (ADS)

    Wang, Jianguo; Liang, Yandong; Chen, Si

    2016-09-01

    In this study, changes in the metastable zone width of CaCO3 crystallization was determined through conductivity titration by altering electromagnetic field parameters applied to the circulating water system. The critical conductivity value and metastable zone curves of CaCO3 crystallization were determined under different solution concentrations and electromagnetic field intensities. Experimental results indicate that the effect of the electromagnetic field intensity on the critical conductivity value intensifies with the increase of solution concentration. Moreover, the metastable zone width of CaCO3 crystallization increases with the increase of electromagnetic field intensity within 200 Gs, thereby prolonging the induction period of nucleation.

  12. Chronic prenatal exposure to the 900 megahertz electromagnetic field induces pyramidal cell loss in the hippocampus of newborn rats.

    PubMed

    Bas, O; Odaci, E; Mollaoglu, H; Ucok, K; Kaplan, S

    2009-07-01

    Widespread use of mobile phones which are a major source of electromagnetic fields might affect living organisms. However, there has been no investigation concerning prenatal exposure to electromagnetic fields or their roles in the development of the pyramidal cells of the cornu ammonis in postnatal life. Two groups of pregnant rats, a control group and an experimental group, that were exposed to an electromagnetic field were used. For obtaining electromagnetic field offspring, the pregnant rats were exposed to 900 megahertz electromagnetic fields during the 1-19th gestation days. There were no actions performed on the control group during the same period. The offspring rats were spontaneously delivered--control group (n = 6) and electromagnetic field group (n = 6). Offspring were sacrificed for stereological analyses at the end of the 4th week. Pyramidal cell number in rat cornu ammonis was estimated using the optical fractionator technique. It was found that 900 megahertz of electromagnetic field significantly reduced the total pyramidal cell number in the cornu ammonis of the electromagnetic field group (P < 0.001). Therefore, although its exact mechanism is not clear, it is suggested that pyramidal cell loss in the cornu ammonis could be due to the 900 megahertz electromagnetic field exposure in the prenatal period.

  13. [Mechanism of the effect of weak electromagnetic fields on the living body].

    PubMed

    Sidorenko, V M

    2001-01-01

    By using the model conceptions of the dielectric polarization theory, a new mechanism for the effect of electromagnetic field was proposed. The model enables one to explain the experimentally observed influence of low-frequency weak electromagnetic field on biological objects. It was shown that, at the cellular and subcellular levels, an increase in the intensity of the electric component of external electromagnetic field can occur. The magnitude of this increase is determined by the ratio of the contributions of the medium polarization and the depolarizing factor (which depends on body shape) to the total effect. As a result of this increase, a potential comparable with intrinsic biological values can be generated on neuron membranes, which must elicit nervous and physiological responses of the organism.

  14. Growth stimulation of biological cells and tissue by electromagnetic fields and uses thereof

    NASA Technical Reports Server (NTRS)

    Wolf, David A. (Inventor); Goodwin, Thomas J. (Inventor)

    2004-01-01

    The present invention provides systems for growing two or three dimensional mammalian cells within a culture medium facilitated by an electromagnetic field, and preferably, a time varying electromagnetic field. The cells and culture medium are contained within a fixed or rotating culture vessel, and the electromagnetic field is emitted from at least one electrode. In one embodiment, the electrode is spaced from the vessel. The invention further provides methods to promote neural tissue regeneration by means of culturing the neural cells in the claimed system. In one embodiment, neuronal cells are grown within longitudinally extending tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time varying electrical current is conducted, the conductive channels being positioned within a culture medium.

  15. Growth Stimulation of Biological Cells and Tissue by Electromagnetic Fields and Uses Thereof

    NASA Technical Reports Server (NTRS)

    Wolf, David A. (Inventor); Goodwin, Thomas J. (Inventor)

    2002-01-01

    The present invention provides systems for growing two or three dimensional mammalian cells within a culture medium facilitated by an electromagnetic field, and preferably, a time varying electromagnetic field. The cells, and culture medium are contained within a fixed or rotating culture vessel, and the electromagnetic field is emitted from at least one electrode. In one embodiment, the electrode is spaced from the vessel. The invention further provides methods to promote neural tissue regeneration by means of culturing the neural cells in the claimed system. In one embodiment, neuronal cells are grown within longitudinally extending tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time varying electrical current is conducted, the conductive channels being positioned within a culture medium.

  16. [Improvement of light-cured indirect inlays durability by means of electromagnetic field].

    PubMed

    Nidzel'skiĭ, M Ia; Korotetskaia-Zinkevich, V L

    2014-01-01

    The main strength characteristics of light-cured resins used for replacement of dental hard tissues defects are destructive stress by compression, microhardness, resistance to abrasion, impact and water absorption. The study focuses on some strength features of composite materials for inlays processed by electromagnetic field. Four sample series of light cured resin (Charisma, Heraus Kulzer, Germany) were used to assess strength features changes in various curing methods: 10 control samples were polymerized by conventional light-curing device, while 30 were additionally processed by electromagnetic field of various intensity (60, 80 and 100 Oe, 10 samples for each group). The obtained results confirm the positive effects of electromagnetic field on strength features of light-cured resins which improves the quality of inlays.

  17. Separation of particles, suspended in a conducting liquid, with the help of an alternating electromagnetic field

    SciTech Connect

    Korovin, V.M.

    1986-01-01

    The author studies MHD flow at low Reynolds numbers past a spherical particle with conductivity ..cap alpha../sub 1/ greater than or equal to0, moving in a viscous fluid at rest with conductivity ..cap alpha../sub 2/ not = ..cap alpha../sub 1/, filling the interior space of a long solenoid fed by an alternating current. It is shown that aside from the electromagnetic force calculated from the analog of Archimedes' principle, and from the Lorentz force arising from the interaction of eddy currents flowing in th particle with the magnetic field, the particle is also subjected to an electromagnetic propulsive force. A formula relating the local characteristics of the electromagnetic field with the velocity of the particle put into motion by the field but neglecting inertial effects is obtained.

  18. Growth Stimulation of Biological Cells and Tissue by Electromagnetic Fields and Uses Thereof

    NASA Technical Reports Server (NTRS)

    Wolf, David A. (Inventor); Goodwin, Thomas J. (Inventor)

    2002-01-01

    The present invention provides systems for growing two or three dimensional mammalian cells within a culture medium facilitated by an electromagnetic field, and preferably, a time varying electromagnetic field. The cells, and culture medium are contained within a fixed or rotating culture vessel, and the electromagnetic field is emitted from at least one electrode. In one embodiment, the electrode is spaced from the vessel. The invention further provides methods to promote neural tissue regeneration by means of culturing the neural cells in the claimed system. In one embodiment, neuronal cells are grown within longitudinally extending tissue strands extending axially along and within electrodes comprising electrically conductive channels or guides through which a time varying electrical current is conducted, the conductive channels being positioned within a culture medium.

  19. Particle Production in Strong Electromagnetic Fields in Relativistic Heavy-Ion Collisions

    DOE PAGES

    Tuchin, Kirill

    2013-01-01

    I reviewmore » the origin and properties of electromagnetic fields produced in heavy-ion collisions. The field strength immediately after a collision is proportional to the collision energy and reaches ~ m π 2 at RHIC and ~ 10 m π 2 at LHC. I demonstrate by explicit analytical calculation that after dropping by about one-two orders of magnitude during the first fm/c of plasma expansion, it freezes out and lasts for as long as quark-gluon plasma lives as a consequence of finite electrical conductivity of the plasma. Magnetic field breaks spherical symmetry in the direction perpendicular to the reaction plane, and therefore all kinetic coefficients are anisotropic. I examine viscosity of QGP and show that magnetic field induces azimuthal anisotropy on plasma flow even in spherically symmetric geometry. Very strong electromagnetic field has an important impact on particle production. I discuss the problem of energy loss and polarization of fast fermions due to synchrotron radiation, consider photon decay induced by magnetic field, elucidate J / ψ dissociation via Lorentz ionization mechanism, and examine electromagnetic radiation by plasma. I conclude that all processes in QGP are affected by strong electromagnetic field and call for experimental investigation.« less

  20. Effects of electric field and structure on the electromagnetically induced transparency in double quantum dot

    NASA Astrophysics Data System (ADS)

    Bejan, D.

    2017-05-01

    We theoretically investigated the effects of electric field and structural parameters of the confining potential on the optical properties of a GaAs/AlGaAs double quantum dot related to the occurrence of the electromagnetically induced transparency phenomenon, using the compact density-matrix formalism and the effective mass approximation. The dependences of the absorption coefficient, refraction index and light group velocity on the Rabi frequency of the control field, intensity of the static electric field, asymmetry parameter of the potential and dot dimension are discussed in detail. It is found that electromagnetically induced transparency occurs in the system for intermediate field values and its transparency window for probe field absorption and sub- and super-luminal frequency interval of the probe field are blueshifted by the increment of the electric field strength and dot dimension but are redshifted by the augment of the asymmetry parameter of the potential.