نتایج جستجو برای: backscatter media
تعداد نتایج: 285634 فیلتر نتایج به سال:
Acoustic backscatter contrast in depositional sediments under salmon farm cages in the Bay of Fundy, Canada, was correlated with localized changes in (unknown) sediment geotechnical properties, as indicated by 4 independent measures of organic enrichment. Sediment total sulfides and redox potentials, enzyme hydrolyzable amino acids, sediment profile imaging and macrofaunal samples, taken at mid...
In previous work, we demonstrated that accurate backscatter coefficient measurements are obtained with a data reduction method that explicitly accounts for experimental factors involved in recording echo data. An alternative, relative processing method for determining the backscatter coefficient and the attenuation coefficient is presented here. This method involves comparison of echo data from...
Dental restorations, fixed prosthodontics, and implants affect dose distribution in head and neck radiation therapy due to the high atomic number of the materials utilized. The backscatter of electrons from metallic materials due to the impinging treatment x-ray results in localized dose enhancements. These dose enhancements cause localized mucositis in patients who have dental work, a signific...
INTRODUCTION We studied ultrasound features of muscle after nerve injury. METHODS We evaluated ultrasound measurements of muscle thickness and backscatter in injured and contralateral uninjured elbow flexors of 51 children with newborn brachial plexus palsy (NBPP) and compared the results to elbow flexor function (Active Movement Scale), defined as normal, moderate, or severe. RESULTS Compa...
QuikSCAT backscatter is generally higher over urban areas than surrounding vegetated areas. Azimuthal anisotropy has been observed over some urban areas, but the strength of the azimuthal anisotropy in the urban backscatter signal has not been well quantified. This study investigates radar azimuthal anisotropy in urban areas. QuikSCAT L1B σ observations are compared for urban, non-urban, and un...
Aerosol extinction profiles are derived from backscatter data by constraining the retrieval with column aerosol optical thickness (AOT), for example from coincident MODIS observations and without reliance on a priori assumptions about aerosol type or optical properties. The backscatter data were acquired with the NASA Langley High Spectral Resolution Lidar (HSRL). The HSRL also simultaneously m...
HAMDAN O, KHALI AZIZ H & ABD RAHMAN K. 2011. Remotely sensed L-band SAR data for tropical forest biomass estimation. Several attempts have been made to obtain forest stand parameters such as stand volume, stand density, basal area, biomass and carbon (C) stocks from synthetic aperture radar (SAR) data. However the relationship between these parameters and radar backscatter has been a challengin...
This study was performed to investigate the relationship between the cyclic variation of integrated backscatter and myocardial wall thickening in stunned myocardium. Different definitions of cyclic variation were evaluated to be able to compare with other studies. Ultrasound data were acquired from 10 open-chested Yorkshire pigs (25-33 kg) at baseline, during regional ischemia and during 30 min...
In the framework of the European Aerosol Research Lidar Network to Establish an Aerosol Climatology (EARLINET), 19 aerosol lidar systems from 11 European countries were compared. Aerosol extinction or backscatter coefficient profiles were measured by at least two systems for each comparison. Aerosol extinction coefficients were derived from Raman lidar measurements in the UV (351 or 355 nm), an...
This article investigates into the feasibility of using gamma radiation Compton backscatter spectra as a means of material characterization, with the view to developing a portable, hand held probe for investigative purposes such as searching for illicit substances hidden in wall or car door cavities.
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