نتایج جستجو برای: attenuation relationship

تعداد نتایج: 600334  

2006
John H. Bradford

I investigate the frequency dependence of attenuation and problems with measuring the intrinsic attenuation in reflection data. It is well established that in many materials attenuation is approximately linear with frequency over the bandwidth of the GPR signal, with a slope characterized by a constant Q* parameter. I show the relationship of Q* to the parameters describing Cole-Cole relaxation...

Journal: :medical journal of islamic republic of iran 0
mb tavakoli from the department of medical physics and medical engineering, school of medicine, isfahan

currently available non-invasive clinical methods for diagnosing osteoporosis are mainly associated with ionizing radiation. ultrasonic assessment of bone disease is a more recent technology. a theoretical explanation for the relationship between ultrasonic parameters and bone structure is necessary. thus, two types of bone samples of perspex (hap) and perspex-glass beads were produced. each ty...

Journal: :iranian journal of nuclear medicine 2006
mohsen bakhshandeh hossein rajabi masoud vafamanesh ali akbar sharafi shahram seifollahi

introduction: nowadays, imaging of the myocardial perfusion (mpi) using the single photon emission tomography (spet) in the diagnosis of coronary artery disease, especially myocardial ischemia, is of great importance. in contrast to the coronary artery angiography, mpi is non-invasive, less expensive and more physiological. unfortunately, this image is affected by the some artifacts. these arti...

Journal: :Journal of medicinal chemistry 2008
Danni Harris Terry Clayton James Cook Peyman Sahbaie Robert F Halliwell Roman Furtmüller Sigismund Huck Werner Sieghart Timothy M DeLorey

Ligands that bind to the benzodiazepine binding site on the GABA A receptor can attenuate or potentiate cognition. To investigate this property, the chemical determinants favoring selective binding or selective activation of the alpha5beta2gamma2 and alpha1beta2gamma2 GABA A receptor isoforms were examined. A 3D-pharmacophore, developed from a diverse set of BDZR ligands, was used as an initial...

Azim Arbabi Hossein Masoumi Manijeh Mokhtari-Dizaji Mohsen Bakhshandeh

Background & Aims: Today, different imaging techniques have been studied in the reading of radiationsensitive polymer gels dosage. Due to limitations of imaging techniques such as magnetic resonance imaging (MRI) and computed tomography (CT), ultrasound techniques are proposed for dose-dependent parameter extraction. In this study, using MAGIC-f (methacrylic and ascorbic acid in gelatin initiat...

Journal: :The Journal of adolescent health : official publication of the Society for Adolescent Medicine 2011
Dhruv Khullar Nicolas M Oreskovic James M Perrin Elizabeth Goodman

PURPOSE To assess whether dispositional optimism is associated with adiposity and to explore whether dispositional optimism mediates the relationship between parent education and adiposity (body mass index [BMI] z-score). METHODS Multivariate regression analyses of data were collected from 1,298 non-Hispanic black and white adolescents aged 12-19 years from a single Midwestern public school d...

Journal: :Applied radiation and isotopes : including data, instrumentation and methods for use in agriculture, industry and medicine 2008
Saxby Brown Dale L Bailey Kathy Willowson Clive Baldock

This study has investigated the relationship between linear attenuation coefficients (mu) and Hounsfield units (HUs) for six materials covering the range of values found clinically. Narrow-beam mu values were measured by performing radionuclide transmission scans using (99m)Tc, (123)I, (131)I, (201)Tl and (111)In. The mu values were compared to published data. The relationships between mu and H...

2011
A. F. Ahmad Z. Abbas Suzan J. Obaiys M. A. Jusoh Z. A. Talib

The analysis and optimal design of a microstrip sensor for measuring the water content of rubber latex is described. The microstrip structure consists of one layer: substrate, protective layer and semi-infinite layer of wet medium. A functional relationship has been developed between the attenuation and the water content of the latex, and close agreement has been found between the computed and ...

2012
Amanda S. Therrien James Lyons Ramesh Balasubramaniam

The Lombard effect describes the automatic and involuntary increase in vocal intensity that speakers exhibit in a noisy environment. Previous studies of the Lombard effect have typically focused on the relationship between speaking and hearing. Automatic and involuntary increases in motor output have also been noted in studies of finger force production, an effect attributed to mechanisms of se...

2002
Hong Cui Elling W. Jacobsen

As chemical plants are becoming more and more tightly integrated, with extensive material and energy recycling, the need for improving their dynamic properties through process design modifications is increasing. However, this is not a trivial task since process integration usually also introduces a relatively complex relationship between properties of the individual units and the overall plant....

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