357 research outputs found

    Kinetic simulations of X-B and O-X-B mode conversion

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    We have performed fully-kinetic simulations of X-B and O-X-B mode conversion in one and two dimensional setups using the PIC code EPOCH. We have recovered the linear dispersion relation for electron Bernstein waves by employing relatively low amplitude incoming waves. The setups presented here can be used to study non-linear regimes of X-B and O-X-B mode conversion.Comment: 4 pages, 3 figure

    Correlation between Laser Fluorescence Readings and Volume of Tooth Preparation in Incipient Occlusal Caries In Vitro

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    This study evaluated the correlation between laser fluorescence readings and the extent of incipient occlusal caries as measured by the volume of tooth preparation in vitro.One hundred and three permanent molars and premolars containing incipient occlusal pit-and-fissure caries and sound occlusal surfaces (1/4 of the sample, control) were selected. DIAGNOdent (KaVo Dental Corporation, Lake Zurich, IL, USA) readings were obtained according to manufacturer instructions. Caries was removed with 1/4 round burs in high speed. The volume of tooth preparation was measured using a surrogate measure based on the amount of composite needed to fill the preparations. Sensitivity and specificity using different cutoff values were calculated for lesions/preparations extending into dentin. The results were analyzed statistically.The Pearson correlation for preparation volume and DIAGNOdent reading measurements was low ( r  = 0.285). Sensitivity and specificity of DIAGNOdent for detection of dentinal lesions were 0.83 and 0.60, and 0.66 and 0.73 for the cutoff values of 20 and 30, respectively.Within the limitations of this study, laser fluorescence measured with DIAGNOdent does not correlate well with extent of carious tooth structure in incipient occlusal caries.Clinicians should not rely only on DIAGNOdent readings to determine the extension of incipient occlusal caries.( J Esthet Restor Dent 22:31–41, 2010)Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78687/1/j.1708-8240.2009.00309.x.pd

    Recent progress with the MAST synthetic aperture imaging radiometer

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    The MAST Synthetic Aperture Microwave Imaging (SAMI) radiometer is an antenna array designed to image thermal microwave emission from MAST fusion plasmaaSAMl is now installed on MAST and preliminary data has been taken. This data clearly show the presence of electrostatic to electromagnetic mode conversion and the circumstances under which this mode conversion take place are strongly related to the pedestal density gradient and magnetic field. These quantities are valuable in understanding tokamak pedestal behaviour and are especially important to models of the Edge Localised Mode (ELM). This paper describes SAMIs design and construction, as well as fist signals showing the presence of mode conversion

    A high-k mm-wave scattering diagnostic for measuring binormal wavenumber electron scale turbulence on MAST-U

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    We describe a high-k mm-wave scattering diagnostic for measuring binormal wavenumber electron scale turbulence on the MAST-U spherical tokamak. Gaussian wave optics and beam-tracing calculations are presented that show the predicted spatial and wavenumber resolution of the diagnostic along with the sensitivity of measurement. The proposed system will operate at a frequency of 376GHz and will facilitate adjustable localization of the turbulence measurement from the magnetic axis out to the plasma edge
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