introduction: the main goal of spect imaging is to determine activity distribution inside the organs of the body. however, due to photon attenuation, it is almost impossible to do a quantitative study. in this paper, we suggest a mathematical relationship between activity distribution and its corresponding projections using a transfer matrix. monte carlo simulation was used to find a precise tr...

At present, one of the main methods minimizing risk resulting from electromagnetic information leakage is to attenuate undesired levels radiated and conducted disturbances generated by IT equipment, as these can carry processed said equipment. Attenuation compromising emissions most commonly handled with filters a sufficiently high insertion loss. This article defines an original analytical rel...

introduction: photon attenuation in tissues is the primary physical degrading factor limiting both visual qualitative interpretation and quantitative analysis capabilities of reconstructed single photon emission computed tomography (spect) images. the aim of present study was to investigate the effect of attenuation correction on the detection of activation foci following statistical analysis w...

objective(s): in spect, the sinogram contains scatter and lack of attenuated counts that degrade the reconstructed image quality and quantity. many techniques for attenuation and scatter correction have been proposed. an acceptable method of correction is to incorporate effects into an iterative statistical reconstruction. here, we propose new maximum likelihood expectation maximization (mlem) ...

the strong ground motions recorded during the 2002 avaj earthquake have been used to estimates wave attenuation, qβ, and spectral decay parameter, κ, for the avaj region. qβ for shear wave is estimatedas a function of frequency in the range of 0.6- 18 hz. the results show that qβ increases with frequency in theform of qβ=62.7 f 0.9. our estimates are within the estimated range for different par...

a considerable amount of energy is released in the form of shock wave from explosive charge detonation. shock wave energy is responsible for the creation of crushing and fracture zone around the blast hole. the rest of the shock wave energy is transferred to rock mass as ground vibration. ground vibration is conveyed to the adjacent structures by body and surface waves. geological structures li...

Characteristics of ground motions close to the earthquake source can be considerably different from those of far-field motions which should be considered in design process of structures. The current study aimed to present new design response spectra for Iranian seismic design code taking into account the near-fault effects. For this purpose, a new attenuation relation based on the ground motion...

We examined the attenuation and integration of spontaneous excitatory postsynaptic potentials (sEPSPs) in the dendrites of presumed motoneurons (MNs) of organotypic rat spinal cord cultures. Simultaneous whole cell recordings in current-clamp mode were made from either the soma and a dendrite or from two dendrites. Direct comparison of the two voltage recordings revealed that the membrane poten...

Abstract We consider the propagation of gravitational waves in late-time Universe presence matter distribution inhomogeneities, and we also cosmic fluid to be viscous. In this work, investigate cumulative effect inhomogeneities viscosity cosmic-fluid on observables associated with sources waves. Employing Buchert’s averaging procedure backreaction framework, a model spacetime which is distribut...