Search results for "electromagnetic"
showing 10 items of 1595 documents
Optical absorption of torus-shaped metal nanoparticles in the visible range
2007
Received 22 November 2007; published 19 December 2007We theoretically and experimentally investigated the optical response of a thin metal nanotorus in the visiblerange. The close formulas describing the extinction cross sections of a torus are obtained in the nonretardedapproximation. We demonstrate a good agreement between numerical simulations and experimental data. Ourfindings show that the main resonance is highly sensitive to the external medium and the geometrical param-eters of the particle.DOI: 10.1103/PhysRevB.76.245422 PACS number s : 78.67.Bf, 73.20.Mf, 78.20.Ci
Lack of mutagenic and co-mutagenic effects of magnetic fields during magnetic resonance imaging
2001
Mutagenic and co-mutagenic effects of static, pulsed bipolar gradient, and high-frequency magnetic fields, as well as combinations of them, were examined using the Ames test. The Ames test using Salmonella typhimurium bacteria, wild-type strain RTA, preincubation assay, without metabolic activation, was performed. All combinations of magnetic fields were tested with and without co-exposure to N-methyl-N′-nitro-N-nitrosoguanidine and benzo[a]pyrene-4,5-oxide, ethylene oxide, carboplatin, or cisplatin. As expected, chemical mutagens caused a clear-cut increase of the revertants in the Ames test. However, neither the static fields nor a combination of a static magnetic field with the time-vary…
SU-FF-T-62: Dosimetric Evaluation of An Internal Shielding Used with a HDR Skin Applicator
2009
Purpose: The Valencia HDR skin applicators are accessories of the microSelectron HDR afterloading system (Nucletron) cup shaped to limit the dose to the irradiation area. Applicators sizes are: diameter 2 and 3 cm. The typical prescription depth is 3 mm. This work aims to evaluate the backscatter and electron contamination of an internal shielding used to reduce the dose to the ocular globe when the lesion is located at the eyelid. Monte Carlo(MC) and experimental methods have been used. Method and Materials: The geometry has been: the Valencia applicator (2 cm diameter) on the surface of a solid polystyrene slab phantom; inside, a 2 mm lead slab located at 3 mm depth. MC simulation charact…
Study of a Novel High Permeability Ferrite Sheet Intended for Near Field Communication Systems
2019
The reduction of embedded portable devices involves a magnetic field interference problem when it integrates Near Field Communication (NFC) due to the presence of conductive surfaces such as ground planes, batteries or metallic enclosures. This contribution is focused on analyzing the ability of an innovative magnetic shielding based on flexible sintered ferrite sheets (FSFS) with the aim of improving the performance of that kind of systems. Thereby, a NFC emitter antenna is characterized when it is close to a conductive surface through an electromagnetic (EM) scanner. The EM scanner composed by a matrix of near field probes that make it possible to determine the effectiveness of the FSFS. …
Transcranial Magnetic Resonance Imaging-Guided Focused Ultrasound with a 1.5 Tesla Scanner: A Prospective Intraindividual Comparison Study of Intraop…
2021
Background: High-quality intraoperative imaging is needed for optimal monitoring of patients undergoing transcranial MR-guided Focused Ultrasound (tcMRgFUS) thalamotomy. In this paper, we compare the intraoperative imaging obtained with dedicated FUS-Head coil and standard body radiofrequency coil in tcMRgFUS thalamotomy using 1.5-T MR scanner. Methods: This prospective study included adult patients undergoing tcMRgFUS for treatment of essential tremor. Intraoperative T2-weighted FRFSE sequences were acquired after the last high-energy sonication using a dedicated two-channel FUS-Head (2ch-FUS) coil and body radiofrequency (body-RF) coil. Postoperative follow-ups were performed at 48 h usin…
Imaging of Located Buried Defects in Metal Samples by an Scanning Microwave Microscopy
2011
Abstract A non-destructive method is proposed to detect the located buried defects using scanning microwave microscopy. Based on the “skin effect”, our recent developments authorize 3D tomography with nanometric resolution. This technique associates the electromagnetic microwave measurement using a Vector Network Analyzer (VNA) with the nanometer-resolution positioning capabilities of an Atomic Force Microscope. At each used frequency, an incident electromagnetic wave is send to the sample and the reflected wave gives information on a specific depth layer in the material. With a large bandwidth of frequencies, a 3D tomography is allowed inside the material. With characteristic tools of nano…
Analysis of the atmospheric and emissivity influence on the splitwindow equation for sea surface temperature
1994
Abstract In this paper we have analysed the effects of the different atmospheric species (water vapour, fixed gases and aerosols) and the surface emissivity on the split-window method for determining the sea surface temperature. The widely used split-window method is based on the differential absorption of water vapour in the atmospheric window 10.5ndash;12.5 μm. Other atmospheric species with absorption coefficients different to that of water vapour can then have a large influence on the split-window. The effect of gases, such as C02, N20, CH4, CO and 03, and maritime aerosols is evaluated by comparing the effect of the water vapour alone. To do this we simulated AVHRR measurements in chan…
EP-1590: Shielding design and fetal dose evaluation of a breast cancer pregnant patient undergoing HDR Ir-192 brachytherapy
2015
New insights into seismic absorption imaging
2020
Abstract In recent years, attenuation has been used as a marker for source and dynamic Earth processes due to its higher sensitivity to small variations of lithospheric properties compared to seismic velocity. From seismic hazard analysis to oil and gas exploration and rock physics, many fields need a better reconstruction of energy absorption, a constituent of seismic attenuation generally considered a reliable marker of fluid saturation in space. Here, we propose absorption tomography (AT), a technique grounded on the principles of scattering tomography and Multiple Lapse Time Window Analysis. We benchmark its efficiency to image absorption in space by comparing its results with those obt…
Structure determination and homogeneous optical properties of CdS/HgS quantum dots
1997
The structural and optical properties of heterogeneous semiconductor nanoparticles consisting of CdS and HgS are investigated by High Resolution Electron Microscopy (HRTEM) and selective spectroscopy like Hole Burning (HB) and Fluorescence Line Narrowing (FLN). The HRTEM study shows that epitaxy is possible in nanocrystals, provided the crystallites have well defined faceted shapes to begin with. From the HB- and FLN experiments homogeneous absorption and fluorescence spectra are calculated. It could be shown that the absorption is coupled to HgS-like phonons (250 cm -1 ) whereas the emission frequency is closer to the LO phonon frequency of CdS.