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Electromagnetic Radiation

P Lunkenheimer, S Emmert, R Gulich, M Köhler, M Wolf, M Schwab, A Loidl
Why does a microwave oven work? How does biological tissue absorb electromagnetic radiation? Astonishingly, we do not have a definite answer to these simple questions because the microscopic processes governing the absorption of electromagnetic waves by water are largely unclarified. This absorption can be quantified by dielectric loss spectra, which reveal a huge peak at a frequency of the exciting electric field of about 20 GHz and a gradual tailing off toward higher frequencies. The microscopic interpretation of such spectra is highly controversial and various superpositions of relaxation and resonance processes ascribed to single-molecule or molecule-cluster motions have been proposed for their analysis...
December 2017: Physical Review. E
Julio C Hernández, J Adrián Reyes
We analyzed the optical band gaps for axially propagating electromagnetic waves throughout a metallic doped cholesteric elastomer. The composed medium is made of metallic nanospheres (silver) randomly dispersed in a cholesteric elastomer liquid crystal whose dielectric properties can be represented by a resonant effective uniaxial tensor. We found that the band gap properties of the periodic system greatly depend on the volume fraction of nanoparticles in the cholesteric elastomer. In particular, we observed a displacement of the reflection band for quite small fraction volumes whereas for larger values of this fraction there appears a secondary band in the higher frequency region...
December 2017: Physical Review. E
Yu O Averkov, Yu V Prokopenko, V M Yakovenko
The interaction between a tubular beam of charged particles and a dispersive metamaterial of cylindrical configuration has been investigated theoretically. This metamaterial may have negative permittivity and negative permeability simultaneously over a certain frequency range where it behaves like a left-handed metamaterial. The dispersion equation for the eigenmodes spectra of a metamaterial and the coupled modes spectra of the system have been derived and numerically analyzed. It has been found that the absolute beam instability of bulk-surface waves occurs because of peculiarities of the eigenmodes spectra of a left-handed metamaterial...
July 2017: Physical Review. E
Johan F Triana, Daniel Pelaez Ruiz, Jose Luis Sanz-Vicario
The quantum photodynamics of a simple diatomic molecule with a permanent dipole immersed within an optical cavity containing a quantized radiation field is studied in detail. The chosen molecule under study, lithium fluoride (LiF), is characterized by the presence of an avoided crossing between the two lowest 11Σ potential energy curves (covalent-ionic diabatic crossing). Without field, after prompt excitation from the ground state 11Σ, the excited nuclear wave packet moves back and forth in the upper 21Σ state, but in the proximity of the avoided crossing, the non-adiabatic coupling transfers part of the nuclear wave packet to the lower 11Σ state, which eventually leads to dissociation...
January 16, 2018: Journal of Physical Chemistry. A
Jean-Michel Friedt, Gilles Martin, Gwenhael Goavec-Mérou, David Rabus, Sébastien Alzuaga, Lilia Arapan, Marianne Sagnard, Émile Carry
Passive wireless transducers are used as sensors, probed by a RADAR system. A simple way to separate the returning signal from the clutter is to delay the response, so that the clutter decays before the echoes are received. This can be achieved by introducing a fixed delay in the sensor design. Acoustic wave transducers are ideally suited as cooperative targets for passive, wireless sensing. The incoming electromagnetic pulse is converted into an acoustic wave, propagated on the sensor substrate surface, and reflected as an electromagnetic echo...
January 16, 2018: Sensors
Kemal Ertilav, Fuat Uslusoy, Serdar Ataizi, Mustafa Nazıroğlu
Mobile phone providers use electromagnetic radiation (EMR) with frequencies ranging from 900 to 1800 MHz. The increasing use of mobile phones has been accompanied by several potentially pathological consequences, such as neurological diseases related to hippocampal (HIPPON) and dorsal root ganglion neuron (DRGN). The TRPV1 channel is activated different stimuli, including CapN, high temperature and oxidative stress. We investigated the contribution TRPV1 to mitochondrial oxidative stress and apoptosis in HIPPON and DRGN following long term exposure to 900 and 1800 MHz in a rat model...
January 13, 2018: Metabolic Brain Disease
Tiecheng Wang, Shihao Zhang
Second harmonic generation from the two-layer structure where a transition-metal dichalcogenide monolayer is put on a one-dimensional grating has been studied. This grating supports bound states in the continuum which have no leakage lying within the continuum of radiation modes, we can enhance the second harmonic generation from the transition-metal dichalcogenide monolayer by more than four orders of magnitude based on the critical field enhancement near the bound states in the continuum. In order to complete this calculation, the scattering matrix theory has been extended to include the nonlinear effect and the scattering matrix of a two-dimensional material including nonlinear terms; furthermore, two methods to observe the bound states in the continuum are considered, where one is tuning the thickness of the grating and the other is changing the incident angle of the electromagnetic wave...
January 8, 2018: Optics Express
Wei Guo
In this work, a dielectric at a finite temperature is modeled as an ensemble of identical atoms moving randomly around where they are trapped. Light reflection from the dielectric is then discussed in terms of atomic radiation. Specific calculation demonstrates that because of the atoms' thermal motion, Brewster's angle is, in principle, temperature-dependent, and the dependence is weak in the low-temperature limit. What is also found is that the Brewster's angle is nothing but a result of destructive superposition of electromagnetic radiation from the atoms...
January 1, 2018: Journal of the Optical Society of America. A, Optics, Image Science, and Vision
Sungho Choi, Hwanjeong Cho, Matthew S Lindsey, Cliff J Lissenden
Elevated temperature, gamma radiation, and geometric constraints inside dry storage casks for spent nuclear fuel represent a harsh environment for nondestructive inspection of the cask and require that the inspection be conducted with a robotic system. Electromagnetic acoustic transducers (EMATs) using non-contact ultrasonic transduction based on the Lorentz force to excite/receive ultrasonic waves are suited for use in the robotic inspection. Periodic permanent magnet EMATs that actuate/receive shear horizontal guided waves are developed for application to robotic nondestructive inspection of stress corrosion cracks in the heat affected zone of welds in stainless steel dry storage canisters...
January 11, 2018: Sensors
Chao Tang, Chuanjun Yang, Hui Yu, Shen Tian, Xiaomei Huang, Weiyi Wang, Peng Cai
Photosynthesis of Microcystis aeruginosa under Electromagnetic Radiation (1.8 GHz, 40 V/m) was studied by using the proteomics. A total of 30 differentially expressed proteins, including 15 up-regulated and 15 down-regulated proteins, were obtained in this study. The differentially expressed proteins were significantly enriched in the photosynthesis pathway, in which the protein expression levels of photosystems II cytochrome b559 α subunit, cytochrome C550, PsbY, and F-type ATP synthase (a, b) decreased...
January 11, 2018: Scientific Reports
Andrea Zangari, Davide Micheli, Roberta Galeazzi, Antonio Tozzi
Electromagnetic radiation, in the visible and infrared spectrum, is increasingly being investigated for its possible role in the most evolved brain capabilities. Beside experimental evidence of electromagnetic cellular interactions, the possibility of light propagation in the axon has been recently demonstrated using computational modelling, although an explanation of its source is still not completely understood. We studied electromagnetic radiation onset and propagation at optical frequencies in myelinated axons, under the assumption that ion channel currents in the node of Ranvier behave like an array of nanoantennas emitting in the wavelength range from 300 to 2500 nm...
January 11, 2018: Scientific Reports
Osman Balci, Nurbek Kakenov, Ertugrul Karademir, Sinan Balci, Semih Cakmakyapan, Emre O Polat, Humeyra Caglayan, Ekmel Özbay, Coskun Kocabas
Metamaterials bring subwavelength resonating structures together to overcome the limitations of conventional materials. The realization of active metadevices has been an outstanding challenge that requires electrically reconfigurable components operating over a broad spectrum with a wide dynamic range. However, the existing capability of metamaterials is not sufficient to realize this goal. By integrating passive metamaterials with active graphene devices, we demonstrate a new class of electrically controlled active metadevices working in microwave frequencies...
January 2018: Science Advances
Kyu Been Kwon, Teyoun Kang, Hyung Seon Song, Young-Kuk Kim, Bernhard Ersfeld, Dino A Jaroszynski, Min Sup Hur
Emission of radiation from electrons undergoing plasma oscillations (POs) at the plasma frequency has attracted interest because of the existence of intriguing and non-trivial coupling mechanism between the electrostatic PO and the emitted electromagnetic wave. While broadband emission from plasma waves in inhomogeneous plasma is well known, the underlying physics of narrowband emission at the plasma frequency observed in experiments and in solar radio-bursts is obscure. Here we show that a spatially-localized plasma dipole oscillation (PDO) can be generated when electrons are trapped in a moving train of potential wells produced by the ponderomotive force of two slightly detuned laser pulses that collide in plasma and give rise to a burst of quasi-monochromatic radiation...
January 9, 2018: Scientific Reports
Massimo Zecchin, Mara Severgnini, Alba Fiorentino, Vincenzo Livio Malavasi, Loris Menegotti, Filippo Alongi, Domenico Catanzariti, Barbara Alicja Jereczek-Fossa, Michele Stasi, Elvio Russi, Giuseppe Boriani
The management of patients with a cardiac implanted electronic device (CIED) receiving radiotherapy (RT) is challenging and requires a structured multidisciplinary approach. A consensus document is presented as a result of a multidisciplinary working group involving cardiac electrophysiologists, radiation oncologists and physicists in order to stratify the risk of patients with CIED requiring RT and approaching RT sessions appropriately. When high radiation doses and beam energy higher than 6MV are used, CIED malfunctions can occur during treatment...
December 24, 2017: International Journal of Cardiology
Sachiko Kodera, Jose Gomez-Tames, Akimasa Hirata
BACKGROUND: Two international guidelines/standards for human protection from electromagnetic fields define the specific absorption rate (SAR) averaged over 10 g of tissue as a metric for protection against localized radio frequency field exposure due to portable devices operating below 3-10 GHz. Temperature elevation is suggested to be a dominant effect for exposure at frequencies higher than 100 kHz. No previous studies have evaluated temperature elevation in the human head for local exposure considering thermoregulation...
January 8, 2018: Biomedical Engineering Online
Andrew M Harris
OBJECTIVE: To compare radiation dosage to the Urologist using an over-couch system, X-ray tube over table, and an under-couch system, X-ray tube under table. Urologist continue to perform more endoscopic surgery requiring fluoroscopy. Fluoroscopy, or electromagnetic radiation, can cause cellular damage when passing through tissue. These systems are compared with respect to radiation dosage to the urologist. METHODS: A single urologic surgeon utilized a dosimeter badge while using an over-couch system...
January 2, 2018: Urology
William C Jackson, Robert T Dess, Dale W Litzenberg, Pin Li, Matthew Schipper, Seth A Rosenthal, Garrick C Chang, Eric M Horwitz, Robert A Price, Jeff M Michalski, Hiram A Gay, John T Wei, Mary Feng, Felix Y Feng, Howard M Sandler, Robert E Wallace, Daniel E Spratt, Daniel A Hamstra
PURPOSE: The use of stereotactic body radiation therapy (SBRT) for prostate cancer has been reported predominantly from single institutional studies, although concerns for broader adoption exist. METHODS AND MATERIALS: From 2011 through 2013, 66 men were accrued to a phase 2 trial at 5 centers. SBRT consisted of 5 fractions of 7.4 Gy to a total dose of 37 Gy using conventional linear accelerators. Electromagnetic transponders were used for motion management. Health-related quality of life (HRQOL) was evaluated via the Expanded Prostate Cancer Index Composite 26 questionnaire...
January 2018: Practical Radiation Oncology
Javier Cardona, Martin B Sweatman, Leo Lue
The dielectric response of fluids to electromagnetic radiation in the microwave region originates from processes occurring at the molecular level. Understanding these processes in more detail is relevant to many fields, such as microwave heating, fluid mixing, and separation technologies. In this work, we use molecular dynamics simulations to study the dielectric spectra of ethanol/water mixtures. We compare our predictions with experimental results at different compositions. We show how the dielectric response can be estimated to a high level of accuracy using three dielectric relaxations: a dominant and slower process at microwave frequencies and two faster processes...
January 4, 2018: Journal of Physical Chemistry. B
Yan-Yun Lin, Tao Wu, Jun-Ye Liu, Peng Gao, Kang-Chu Li, Qi-Yan Guo, Meng Yuan, Hai-Yang Lang, Li-Hua Zeng, Guo-Zhen Guo
More studies that are focused on the bioeffects of radio-frequency (RF) electromagnetic radiation that is generated from the communication devices, but there were few reports with confirmed results about the bioeffects of RF radiation on reproductive cells. To explore the effects of 1950 MHz RF electromagnetic radiation (EMR) on mouse Leydig (TM3) cells. TM3 cells were irradiated or sham-irradiated continuously for 24 h by the specific absorption rate (SAR) 3 W/kg radiation. At 0, 1, 2, 3, 4, and 5 days after irradiation, cell proliferation was detected by cell counting kit-8 (CCK-8) method, cell cycle distribution, percentage of apoptosis, and cellular reactive oxygen species (ROS) were examined by flow cytometry, Testosterone level was measured using enzyme-linked immunosorbent assay (ELISA) assay, messenger ribonucleic acid (mRNA) expression level of steroidogenic acute regulatory protein (StAR) and P450scc in TM3 cells was detected by real-time polymerase chain reaction (PCR)...
December 23, 2017: International Journal of Environmental Research and Public Health
M Schanz, M Endres, K Löwe, T Lienig, O Deppert, P M Lang, D Varentsov, D H H Hoffmann, O Gutfleisch
Permanent magnet quadrupoles (PMQs) are an alternative to common electromagnetic quadrupoles especially for fixed rigidity beam transport scenarios at particle accelerators. Using those magnets for experimental setups can result in certain scenarios, in which a PMQ itself may be exposed to a large amount of primary and secondary particles with a broad energy spectrum, interacting with the magnetic material and affecting its magnetic properties. One specific scenario is proton microscopy, where a proton beam traverses an object and a collimator in which a part of the beam is scattered and deflected into PMQs used as part of a diagnostic system...
December 2017: Review of Scientific Instruments
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