نتایج جستجو برای: attenuation relationships
تعداد نتایج: 275770 فیلتر نتایج به سال:
bioremediation, the process by which microorganisms degrade organic compounds to non-toxic or less toxic substances, has been widely used for cleanup of coastal ecosystems after oil spills. in this study, the hydrocarbon degradation rate and half lives in three bioremediation strategies (natural attenuation, biostimulation, and bioaugmentation) were compared in weathered crude oil (wco) contami...
ultrasonic testing (ut), a nondestructive testing (ndt) method, is under development for quality determination of agricultural products, although it has long been used in the food industry. determination and measurement of product quality are important in modern agricultural research. noninvasive/nondestructive quality determination is a novel aspect of the postharvest process in which paramete...
introduction: the main purpose of this study was to compare transient ischemic dilation (tid) ratios in spect-low dose ct and spect myocardial perfusion imaging (mpi) by application of different quantitative programs and quantify the possible shift in the upper normal limits of tid ratio in the spect-ct mpi. methods: 149 patients with low pre-test probability for coronary artery disease (cad),...
it has been proved that ultrasonic energy can considerably increase the amount of oil recovery in animmiscible displacement process. although many studies have been performed on investigating theroles of ultrasonic waves, based on the best of our knowledge, little attention has been paid to evaluatewave attenuation parameter, which is an important parameter in the determination of the energydel...
objective: in this study, we aimed to validate the accuracy of computed tomography-based attenuation correction (ctac) using the bilinear scaling method.methods: the measured attenuation coefficient (μm) was compared to a theoretical attenuation coefficient (μt ) using four different ct scanners and an rmi 467 phantom. the effective energy of the ct beam x-rays was calculated, using the aluminu...
OBJECTIVES To investigate how 3 measures of health literacy correlate with age and the explanatory roles of fluid and crystallised cognitive abilities in these relationships among older adults. DESIGN Cross-sectional baseline analysis of the 'LitCog' cohort study. SETTING 1 academic internal medicine clinic and 5 federally qualified health centres in Chicago, USA. PARTICIPANTS English-spe...
Estimating total ultrasound attenuation from backscatter data is essential in the field of quantitative ultrasound (QUS) because of the need to compensate for attenuation when estimating the backscatter coefficient and QUS parameters. This work uses a reference phantom method of attenuation estimation to create a spatial map of attenuation slope (AS) from backscatter radio-frequency (RF) data o...
Prokaryotic transcription attenuation mechanisms are described in which different metabolic signals and sensing events are used to regulate transcription termination at sites preceding structural genes. Suggestive eukaryotic examples also are mentioned.
Rhizophora wood exhibits characteristics of interaction with radiation similar to those of water. Recently, a novel model based on MCNP4C code has been proposed for calculation of mass attenuation coefficients for some polymers. The aim of this study is to determine the mass attenuation coefficients for Rhizophora wood in energy range 15.77-60 keV using this model. First, the mentioned model wa...
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