Current Issue : January - March Volume : 2020 Issue Number : 1 Articles : 5 Articles
The application of the grazing-incidence small-angle X-ray scattering (GISAXS) technique\nfor the investigation of three-dimensional lattices of nanostructures is demonstrated. A successful\nanalysis of three-dimensionally ordered nanostructures requires applying a suitable model for the\ndescription of the nanostructure ordering. Otherwise, it is possible to get a good agreement between\nthe experimental and the simulated data, but the parameters obtained by fitting may be completely\nincorrect. In this paper, we theoretically examine systems having different types of nanostructure\nordering, and we show how the choice of the correct model for the description of ordering influences\nthe analysis results. Several theoretical models are compared in order to show how to use GISAXS\nin the investigation of self-assembled arrays of nanoparticles, and also in arrays of nanostructures\nobtained by ion-beam treatment of thin films or surfaces. All models are supported by experimental\ndata, and the possibilities and limitations of GISAXS for the determination of material structure\nare discussed....
Our study aims to determine diagnostic reference levels (DRL) for chest front\nexamination in postero anterior (PA) for optimizing patient entrance surface\ndose (ESD) and dose-area product (DAP) of patients in west of Cote dâ??Ivoire.\n90 patients from three hospitals undergoing conventional radiology were\nconsidered. The ESD and DAP for each patient were obtained during chest\nradiography (PA) examination. The measurements were performed with the\ndevice call Dose-Area Product-meter (DAP-meter) with brand Diamentor\nM4-KDK, type 11017. The DRL were obtained in applying the 75th percentile\nstatistical method to the obtained ESD and DAP. The obtained DRL in ESD\nfor chest radiography for all rooms is 0.40 mGy and in DAP is 54.85 cGy.cm^2.\nOur DRL for ESD is higher than those obtained in Abidjan District and in\nother countries like UK and Cameroon. Our DRL for DAP is higher than\nthose from Abidjan and all other countries for which a similar study was\nmade. The comparison of these values to those from Abidjan and other\ncountries, shows us that radiology technicians can make efforts to choose radiological\nparameters to reduce ESD. They must use convenable the X-rays\ntube to reduce DAP by reducing the patient exposure surface....
The observed properties of Gamma-Ray Bursts such as rapid variability of\nX-ray light curve and large energies strongly signature the compact binary,\ndisk accreting system. Our work particularly highlights the extremely rotating,\ndisk accreting black holes as physical source of the flares variability and\nX-ray afterglow plateaus of GRBs. We investigate the compact binary mergers\n(neutron star - neutron star and neutron star onto black hole) and gravitational\ncore collapse of super massive star, where in both cases hyper-accreting\nKerr hole is formed. The core collapse in a powerful gravitational wave explained\nas a potential source for the radiated flux of hard X-rays spectrum.\nWe described the evolution of rapidly rotating, accreting BH in general relativity\nand the relativistic accretion flow in resistive MHD for viscous radiation.\nWe compute the structure of accretion disk, the accretion luminosity of\nthe dynamical evolution of inner accretion disk and precisely determine their\nradiation spectra, and compare to observational data of X-ray satellites. Finally,\nwe obtained the resulting disk radiation basically explained as the X-ray\nluminosity of the central source, such as LMC X-1 and GRO J1655-40. These\nresults are interestingly consistent with observational data of galactic X-ray\nsource binary systems such as X-ray luminosities of Cygnus X-1 and Seyfert\ngalaxies (NGC 3783, NGC 4151, NGC 4486 (Messier 87)) which are powerful\nemitters in X-ray and gamma-ray wavebands of the observed X-ray variability\nwith typical luminosity....
The speed of light in a vacuum is a constant of special relativity, electromagnetic\nwave theories, and astrophysical distances. However, several measurements\nof its speed (c ) at locations on the Earthâ??s surface seem to vary at different\ntimes during the last century. Efforts have been made on instruments\nperformance to achieve a unique viable value in any spacetime referential.\nThe time-variability on c -values obtained is here addressed inside the gravity\nfield (g ) in which the measurements of c have been estimated. It appears a\ncorrelation of c and g both daily (tidal) and yearly (no-tidal) variations which\nsuggest that the gravity acceleration control the c -variability everywhere in a\nspacetime referential. Implications of this model provide a sensitivity constant\nof c from g , and the estimates of c on planets of the solar system where g\nvalues are known. It is deduced an upper limit of gravity in black hole that\ncan cancel the speed of light in the horizon....
The presence of the dark energy allows both the acceleration and the expansion\nof the universe. In the case of a constant equation of state for dark energy\nwe derived an analytical solution for the Hubble radius in terms of the\nhypergeometric function. An approximate Taylor expansion of order seven is\nderived for both the constant and the variable equation of state for dark\nenergy. In the case of the Cardassian cosmology, we also derived an analytical\nsolution for the Hubble radius in terms of the hypergeometric function. The\nastronomical samples of the distance modulus for Supernova (SN) of type Ia\nallows the derivation of the involved cosmological in the case of constant equation\nof state, variable equation of state and Cardassian cosmology....
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