Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 20 of 42 for “"Specific Absorption Rate (SAR)."”.
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IDENTIFICATION OF Cav 3.2 T-TYPE VOLTAGE GATED CALCIUM CHANNELS AS KEY MEDIATORS OF TARGETED INHIBITION OF HEPATOCELLULAR CARCINOMA BY AMPLITUDE-MODULATED RADIOFREQUENCY ELECTROMAGNETIC FIELDS
… mechanism of action w e have a ssessed the Specific Absorption Rate (SAR) level and dis tribution inside the human body . Additionally, we performed various i n vitro and in vivo experiments that were exposed to HCC - specific AM RF EMF using systems replicating human exposure levels and …
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Evaluation of nanoparticles-based thermotherapy for cancer
… iron oxide nanoparticles can be used to generate heat for the treatment of cancer. With suitable coating, these nanoparticles are biocompatible, stable in solution, and absorbed by tumor cells in good contrast. The mechanism of heating is mainly due to Neel relaxation process and a quantity …
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Modeling and calculation of the specific absorption rate for multi-antenna mobile devices
… the human exposure to the RF radiation, the specific absorption rate (SAR) is introduced as a measure. Regulatory agencies have standards limiting the maximum SAR to ensure safety. In order to comply with the regulations, the SAR induced in the human head and body should be evaluated by …
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Influência do tamanho de nanopartículas em suas propriedades de hipertermia magnética
… de campo magnético AC, para o cálculo do Specific Absorption Rate (SAR). Foi observado que existe um limite para o diâmetro da nanopartícula, no qual a relaxação de Neél deixa de ser o mecanismo principal ao aquecimento e a histerese passa a contribuir
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Compact planar wearable ultra wideband antenna for on-body applications
… have been reported in this thesis. The substrates of the proposed antennas have been made of jeans while radiators were made of copper tapes. Simulated and measured performances of the antennas in terms of return loss and radiation patterns have been discussed in this work. Recorded results …
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Investigation, design and implementation of circular-polarised antennas for satellite mobile handset and wireless communications. Simulation and measurement of microstrip patch and wire antennas for handheld satellite mobile handsets and investigations of polarization polarity, specific absorption rate, and antenna design optimization using genetic algorithms.
… antennas are investigated and discussed to operate at L band (1.61-1.6214GHz) and ISM band (2.4835-2.5GHz) A substantial size reduction was achieved compared to conventional designs by introducing special modifications to the antenna geometries. Most of the antennas are designed to produce …
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Coil performance evaluation based on electrodynamics : tools for hardware design and validation in magnetic resonance imaging
… are shown, and coil performance maps are generated based on the ratio of experimentally measured SNR to this ultimate intrinsic SNR. Parallel excitation, which involves independent transmission with multiple RF coils distributed around the body, can be used to improve the homogeneity of RF …
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Parallel transmission for magnetic resonance imaging on a 9.4 Tesla Human System.
… in actual experiments. In this thesis, we demonstrate the first successful implementation of parallel transmission at an ultrahigh field of 9.4 Tesla (T) in the human brain with an eight-channel transmit system, using accelerated (x 4) RF pulses designed to create arbitrarily shaped excitation …
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Fast simulation of E1, B1 and Specific Absorption Rate for 7T MRI with the use of graphical processors
Specific Absorption Rate (SAR) is a dominant constraint in high field MR, and has been a topic of much recent interest with developments of parallel transmission systems (pTx). While real-time estimates of local SAR over large volumes as well as SAR-constrained pTx RF design are highly desirable …
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Numerical field simulation for parallel transmission in MRI at 7 tesla
… improvement to coil design that has been demonstrated to mitigate B1* inhomogeneity, manifest as center brightening, for high-field magnetic resonance imaging (MRI). Parallel transmission achieves spatially-tailored pulses through multiple radiofrequency (RF) excitation coils that can be …
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Mitigating Inhomogeneity in High-Field MRI Excitations: Arbitrary Waveform Optimization and Multiphoton Parallel Transmission (MP-pTx)
… (and ultimately heating), quantified as the specific absorption rate (SAR). To address these challenges, we introduce a method for optimizing patient-specific pulses using a global waveform (Ritz) approach, enabling rapid, in-scanner optimization. While pTx effectively addresses flip angle …
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Enhanced Microwave Hyperthermia using Nanoparticles
… the nanoparticles allow the electromagnetic absorption to be focused in the tumor and can be used to treat deep tumors in organs, such as the liver. Iron oxide magnetic nanoparticles were considered for this study as they are non-toxic and bio-compatible. For the case of breast cancer, the …
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Balanced antennas for mobile handset applications. Simulation and Measurement of Balanced Antennas for Mobile Handsets, investigating Specific Absorption Rate when operated near the human body, and a Coplanar Waveguide alternative to the Balanced Feed.
… on the mobile phone ground plane. The specific absorption rate (SAR) performance of the antenna is also studied experimentally by measuring antenna near field exposure. The measurement results are correlated with the calculated ones. A new dual-band balanced antenna using coplanar …
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Low-power dual-band on-body antenna for wireless body sensor networks
… the optimum design of the on-body antenna to operate as a central antenna for WBAN. Five types of helical antennas are proposed in the present thesishaving a dual-frequency operation at 2.45 GHz and 5.8 GHz. The proposed antennas are optimized to maximize the Signal-to-Noise-Ratio (SNR) and, …
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Interaction of Nanoparticles with RF, AC, and Static Magnetic Fields in Thermal and Non-Thermal Cancer Therapy Applications
… effective in ablating tumors are non-target specific. The dissertation focus on alternate thermal and non-thermal approaches inducing cancer cell apoptosis by external magnetic fields. Nanoparticle based target specific rf hyperthermia is explored by designing an LCR resonator. Specific …
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Multiphoton Parallel Transmit MRI for Flip Angle Mitigation Without SAR Concerns
… power dissipation in the body, known as the specific absorption rate (SAR). In pTx, SAR strongly depends on how the array elements are energized and must be modeled for each excitation pulse using a body model that accurately approximates the subject. This thesis presents a novel use of the …
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Design and comparative performance evaluation of novel mobile handset antennas and their radiative effects on users.
… efficiency and low profile antennas with low absorption losses by the user are desirable. The Planar Inverted-F Antenna (PIFA) is shown to result into low SAR values and high efficiency when operating in the proximity of the user. Despite these advantages, PIFA is also characterised by narrow …
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Magnetic resonance spectroscopic imaging using parallel transmission at 7T
… in this dissertation aims to provide the necessary means for using spectroscopic imaging for reliable and robust whole brain metabolite detection and quantification at high main field strengths. It addresses the challenges mentioned above by improving both the excitation and the readout …
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Implanted Antennas and Intra-Body Propagation Channel for Wireless Body Area Network
… antenna needs to be small while it maintains Specific Absorption Rate (SAR) and is able to cope with the detuning effect due to the electrical properties of human body tissues. Most of the proposed antennas for implanted applications are electric field antennas, which have a high near-zone …
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