In this work, we aim to investigate the dominant scattering and mobility limiting in a one-dimensional semiconductor device, such as gallium arsenide nanowire. First, the interaction of phonon-electron in a one-dimensional semiconductor device is described and then, using the sheet wave function, some of the carrier scatterings of this system is investigated in terms of quantities such as the density of one-dimensional carriers and temperature. These scatterings include phonon scattering, such as the scattering of acoustic phonons, through the deformation potential coupling, the scattering of acoustic phonons by piezoelectric coupling and the scattering of polar optical phonons, which we first computed and then plotted. We have shown that the mobility limited scattering of carriers in the range of low and high temperatures are acoustic phonon deformation potential scattering and polar longitudinal optical phonon scattering respectively. By increase of linear carrier concentration and nanowire radius the mobility of carriers is enhanced in a given temperature. The dominant scattering in the temperature range (4-300K) is deformation potential and is independent of the carrier concentration and nanowire radius. For high carrier density and nanowire radius the dominant scattering in the temperature range (300-500K) is polar optical phonon scattering

Replacing the wormhole geometry with an equivalent medium using the perturbation theory of scattering and the Born approximation, we have calculated the differential scattering cross section of electromagnetic waves by a traversable wormhole. It is shown that scattering at long wavelenghts can essentially distinguish wormhole from ordinary scattering object. Some of the zeros of the scattering cross section are determined which can be used for estimating the radius of the throat of wormholes. The known result that in this kind of scattering the linear polarization remains unchanged is verified here.

One of the most important parameters in x-ray CT imaging is the noise induced by detected scattered radiation. The detected scattered radiation is completely dependent on the scanner geometry as well as size, shape and material of the scanned object. The magnitude and spatial distribution of the scattered radiation in x-ray CT should be quantified for development of robust scatter correction techniques. Empirical methods based on blocking the primary photons in a small region are not able to extract scatter in all elements of the detector array while the scatter profile is required for a scatter correction procedure. In this study, we measured scatter profiles in 64 slice CT scanners using a new experimental measurement. To measure the scatter profile, a lead block array was inserted under the collimator and the phantom was exposed at the isocenter. The raw data file, which contained detector array readouts, was transferred to a PC and was read using a dedicated GUI running under MatLab 7.5. The scatter profile was extracted by interpolating the shadowed area. The scatter and SPR profiles were measured. Increasing the tube voltage from 80 to 140 kVp resulted in an 80% fall off in SPR for a water phantom (d=210 mm) and 86% for a polypropylene phantom (d = 350 mm). Increasing the air gap to 20.9 cm caused a 30% decrease in SPR. In this study, we presented a novel approach for measurement of scattered radiation distribution and SPR in a CT scanner with 64-slice capability using a lead block array. The method can also be used on other multi-slice CT scanners. The proposed technique can accurately estimate scatter profiles. It is relatively straightforward, easy to use, and can be used for any related measurement.

The Earth’s atmosphere is an environment replete with particles of differ-ent sizes with various refractive indices which affect the light radiation traveling through it. The Mie scattering theory is one of the well-known light scattering techniques ap-plicable to modeling of electromagnetic scattering from tiny atmospheric particles or aerosols floating in the air or within the clouds. In this study, the scattering charac-teristics of atmospheric particles are investigated for a wide range of particle types and particle sizes within the framework of Mie’s theory. The scattering and back-scattering coefficients are calculated and it is observed that the maximum scattering occurs for particle sizes comparable to the radiation wavelength while the spherical particles with diameters much greater than the wavelength scatter the least. The calculations were carried out in the MATLAB environment and the results demonstrate that the scat-tering anisotropy has a direct relation with diameter of the particles.

Scattered photons are one of the main causes of degrading the contrast of lesions and resolution in SPECT imaging of the heart that result in error in quantification. The usual technique for the rejection of scattered photons is through energy windowing. However, because of limited energy resolution of current scintillation cameras it is impossible to avoid scatter photons from detection. Modeling of Compton scattering through finding suitable functions was proposed in this study. These functions were used for scatter correction through deconvolution in next step. Monte Carlo simulation was used for creating projections of three different activity sources: a line source passed through left ventricle, a point source placed in left ventricle and finally real activity distribution of Tc-99m in torso organs. All of these sources were placed in a digital attenuation phantom which modeled a real patient body. Images of primary and scattered photons were acquired separately. Convolution and 2D deconvolution in Fourier domain was applied for estimating the primary projections through total ones. In the first step, scatter and total images were modeled as convolution of a modified exponential function with primary image. The best exponent value was determined for each of 64 views (0.115 to 0.150 according to heart to detector distance). In the next step, these functions were used for scatter correction through deconvolution. Sum of the square differences between the primary and scatter corrected images were decreased considerably, myocardium to cavity contrast increased for all of 64 views (34% ± 10%). Good agreement between the real primary and scatter corrected images were also found.Discussion and These results indicate that deconvolution technique for the scatter compensation can significantly reduce the degrading roles of scattering in quantitative SPECT imaging.

Scattered photon is one of the main defects that degrade the quality and quantitative accuracy of nuclear medicine images. Accurate estimation of scatter in projection data of SPECT is computationally extremely demanding for activity distribution in uniform and non-uniform dense media. The objective of this paper is to develop and validate a scatter correction technique that use an accurate analytical model based on Klein_Nishina scatter equation and compare Klein_Nishina scatter estimation with triple energy window. In order to verify the proposed scattering model several cylindrical phantoms were simulated. The linear source in the cylindrical Phantoms was a hot rod filled with 99mTc. K factor defines as the ratio of scatter resulting from MC simulation to scatter estimated from Klein_Nishina formula. Also a SPECT/CT scan of the image quality phantom was acquired. Row data were transferred to a PC computer for scatter estimation & processing of the images using MLEM iterative algorithm in MATLAB software. The scatter and attenuation compensated images by the proposed model had better contrast than uncorrected and only attenuation corrected images. The K-factors that used in proposed model doesn’t vary with different activities & diameters of linear source and they’re just a function of depth and composition of pixels. Based on Mont Carlo simulation data, the K_N formula that used in this study demonstrates better estimation of scattered photons than TEW. Proposed scattered correction algorithm will improve 52.3% in the contrast of the attenuated corrected images of image quality phantom.

Typology of dispersal in peri-urban areas of KarajAbstractThe latest scientific findings in the field of urban sprawl have often focused on typology; Therefore, in the present article, with the aim of identifying different types of scattered urban species in the metropolis of Karaj, an attempt has been made to examine the views on typology, identification criteria of each species and how to classify different species in the metropolis of Karaj. The research area was 10 areas of Karaj metropolis. Data were collected using library and field methods. The data type included demographic data of the Statistics Center and location-based data of the National Mapping Organization and Karaj Municipality. The data analysis method was performed quantitatively using Moran coefficient, kernel density, space arrangement analysis, shape index and Boolean logic. The results indicate that the city of Karaj is experiencing unorganized and ugly growth and is facing different types of urban dispersion. The type of low density and continuous scattering of urban sprawl covers the largest volume of the city area and is mainly located in the urban edges of Karaj. However, there are other types, such as linear or band scattering, jumping scattering, or nodal scattering; But dominance is a continuous, low-density scattering or edge scatter; Therefore, it can be said that dispersal in the city of Karaj has not developed with a single form and pattern; It has been associated with various forms and species.Keywords: Urban Sprawl, Sprawl Typology, Linear Sprawl, Low Density Growth, Discontinuous Physical Growth, Karaj Metropolis  Typology of dispersal in peri-urban areas of KarajAbstractThe latest scientific findings in the field of urban sprawl have often focused on typology; Therefore, in the present article, with the aim of identifying different types of scattered urban species in the metropolis of Karaj, an attempt has been made to examine the views on typology, identification criteria of each species and how to classify different species in the metropolis of Karaj. The research area was 10 areas of Karaj metropolis. Data were collected using library and field methods. The data type included demographic data of the Statistics Center and location-based data of the National Mapping Organization and Karaj Municipality. The data analysis method was performed quantitatively using Moran coefficient, kernel density, space arrangement analysis, shape index and Boolean logic. The results indicate that the city of Karaj is experiencing unorganized and ugly growth and is facing different types of urban dispersion. The type of low density and continuous scattering of urban sprawl covers the largest volume of the city area and is mainly located in the urban edges of Karaj. However, there are other types, such as linear or band scattering, jumping scattering, or nodal scattering; But dominance is a continuous, low-density scattering or edge scatter; Therefore, it can be said that dispersal in the city of Karaj has not developed with a single form and pattern; It has been associated with various forms and species.Keywords: Urban Sprawl, Sprawl Typology, Linear Sprawl, Low Density Growth, Discontinuous Physical Growth, Karaj Metropolis Typology of dispersal in peri-urban areas of KarajAbstractThe latest scientific findings in the field of urban sprawl have often focused on typology; Therefore, in the present article, with the aim of identifying different types of scattered urban species in the metropolis of Karaj, an attempt has been made to examine the views on typology, identification criteria of each species and how to classify different species in the metropolis of Karaj. The research area was 10 areas of Karaj metropolis. Data were collected using library and field methods. The data type included demographic data of the Statistics Center and location-based data of the National Mapping Organization and Karaj Municipality. The data analysis method was performed quantitatively using Moran coefficient, kernel density, space arrangement analysis, shape index and Boolean logic. The results indicate that the city of Karaj is experiencing unorganized and ugly growth and is facing different types of urban dispersion. The type of low density and continuous scattering of urban sprawl covers the largest volume of the city area and is mainly located in the urban edges of Karaj. However, there are other types, such as linear or band scattering, jumping scattering, or nodal scattering; But dominance is a continuous, low-density scattering or edge scatter; Therefore, it can be said that dispersal in the city of Karaj has not developed with a single form and pattern; It has been associated with various forms and species.Keywords: Urban Sprawl, Sprawl Typology, Linear Sprawl, Low Density Growth, Discontinuous Physical Growth, Karaj Metropolis

Scatter radiation is one of the major sources of error in nuclear medicine data processing. Different methods of scatter correction have been introduced in order to improve the quality of data. However the best method is to avoid recording of scatter photons in acquisition. The only difference between scattered and non-scattered photons is the energy. Pulse height analyzer is the only option available to discriminate primary photons from scattered ones. Energy resolution of the gamma camera is gradually improving consequently the energy window width has to be decreased accordingly. In this study we tried to determine the most appropriate energy window width for present gamma camera systems. Methods and Materials: Since it is not possible to retrieve the data spectrum from the most of the gamma camera systems, a simple method was developed to extract the data from the image of the energy spectrum. Using a scatter phantom different level of scatter and count rate were generated and corresponding energy spectrum data were analyzed. It was assumed that around the peak of the spectrum, the primary photons obey a Gaussian distribution. The data were analyzed using three different methods. All methods prove that the optimum window width regarding the present gamma camera energy resolution is 15%. At this level, the scattered radiation is decreased to 5%. In comparison to the conventional widow width of 20%, the sensitivity does not change dramatically. At the present, for most gamma camera, the energy window width of 20% is recommended. However occasionally energy window width of 15% and 25% are also used. In this study the energy spectrum at different levels of scatter were analyzed and the most suitable energy window width was found to be 15% for the gamma camera having approximate energy resolution of 11%. At this window setting the scatter decreases to 5% of the total counts recorded. Visually the quality of the images dose not improves significantly. However accuracy of data quantification improve significantly.

In the present work the first and second order scattering amplitudes and the related phase were calculated in the charge transfer channel. The positronium formation, with the impact of molecular hydrogen ion, has been carried out using multiple channel scattering formulation and transition matrix. The calculation of differential cross section has been done by varying the scattering angle from 0 to 180 in the fixed orientation of the molecule. In the next calculation the scattering angles were fixed while the spatial molecular orientation was varied. At last the calculated differential cross section was compared with available results in the literature. The scattering angle spanned from 0 to 180 degrees in the second order nuclear and electronic terms were calculated while the molecular orientation was assumed to be fixed. Otherwise, the scattering angles were fixed in the calculation of the corresponding amplitudes while the orientation was varied. At last our calculations were compared with available results

In the present work, we studied the α- 4He particle elastic scattering by measuring cross section with halo Effective Field Theory (hEFT) at low energies. In this article, we considered α- 4He elastic scattering in S-wave state at the very low energy. The α- 4He elastic scattering amplitude comprises the initial s-wave strong and Coulomb interaction at leading order. Because of the unnaturally large scattering length of the aαα, it is considered as a halo system. We defined the lagrangian of this system and then calculated the T-matrix for the scattering amplitude at leading order by using of the Feynman diagrams. Data of the α- 4He elastic scattering refer basically to the low energy extending to 0.29 MeV, the total cross section that with this approach has been calculated will be σ_t≃ 16:0226 mb. It was shown that, the presented strategy can be efficiently developed for the other halo nucleus.