We have studied the plane symmetric cosmological solutions for quark matter coupled with the string cloud and domain walls in the context of Rosen’s (General Relativity and Gravitation 4: 435, 1973) bimetric theory. It is observed that, in this theory, string cloud and domain walls do not exist. As we know that, at the early stage of evolution of the universe, domain walls as well as COSMIC STRINGS do appear which lead to the formation of galaxies. Thus, it may be said that the bimetric relativity does not help to describe the early era of the universe.

In this study, nonlinear vibration of axially moving STRINGS in thermal environment is investigated. The vibration characteristics of the system such as natural frequencies, time domain response and stability states are studied at different temperatures. The velocity of the axial movement is assumed to be constant with minor harmonic variations. It is presumed that the system and the environment are in thermal equilibrium. Using Hamilton’ s principle, the system equation of motion, and t† he boundary conditions are derived and then solved by applying Multiple Time Scales (MTS) method. The effect of temperature on the vibration characteristics of the system such as linear and nonlinear natural frequencies, stability, and critical speeds is investigated. Considering ideal and non-ideal boundary conditions for the supports, nonlinear vibration of the system is discussed for three different excitation frequencies. The bifurcation diagrams for ideal and non-ideal boundary conditions are presented under the influence of temperature at various speeds.

In this paper, using simulation code CRPropa3. 0, the propagation of 104 primary COSMIC rays of proton and iron with energy range of 1018 to 1021 eV was simulated. The spectra of the secondary photons and electron-positrons generated in the interactions of ultra-high energy COSMIC rays (UHECRs) with COSMIC background photons were investigated. The photon and electron spectra considered here are generated in photopion production, beta decay, and pair production. The minimum energy of primaries and the spectral index of source injection is changed separately and the effect of these changes on the spectra is investigated. Also, the total primary energy percent which transfers to secondaries, is calculated. It is found that for both primaries, lowering the minimum energy of the primaries leads to the decrease of the flux of secondaries. This also results in the decrease of the total energy percent carried by beta and photopion products and the increase of the energy percent of pair production. Finally, in is shown that by increasing the spectral index, the flux and the energy percent of all secondaries decreases for proton and iron primaries.

In this paper we examine asymptotically anti de Sitter rotating black string solutions of four-dimensional Einsteinian cubic gravity in the presence of nonlinear Born-Infeld electrodynamics. By assuming that the solutions are completely regular at the horizon and studying the asymptotic and near-horizon behavior of the solutions, we compute independently the Hawking temperature, the Wald entropy, the mass, the angular momentum, the charge and the electrostatic potential, and show that the first law of thermodynamics for rotating black STRINGS with non-linear Born-Infeld source holds exactly in Einsteinian cubic gravity. We also show that when the nonlinear parameter goes to infinity, the solutions tend to those obtained from Maxwell’s electrodynamics

In this paper, after addressing various future singularities, predicted for Cosmos, an introductory note on Rastall theory is provided. Thereinafter, considering a flat Universe, the Friedmann equations of Rastall theory are derived, and the possibility of obtaining various singularities are studied in two cases. In the first case, the COSMIC fluid is an isotropic and homogenous fluid while the ratio of its pressure and density is constant. In the second case, the mentioned ratio is not always constant and Universe evolves with a specified rate. The study claims that whereas it is not predicted any future singularity for the first model of cosmos, some types of future singularities may be inevitable in the second one.

COSMIC Rays (CR) travel at speeds essentially indistinguishable from the speed of light. However whilst travelling through magnetic fields, both regular and turbulent, they are delayed behind the light since they are usually charged particles and their paths are not linear. Those delays can be so long that they are an impediment to correctly identifying sources which may be variable in time. Furthermore deduction of CR sources without knowing CR time delays is not possible, so the magnitude of such delays will be discussed and compared to the characteristic time variation of possible COSMIC ray sources.

In this paper, we have presented a power law scaling Kaluza-Klein cosmological model dominated by two interacting perfect fluid components during expansion. Barotropic equations of state for pressure and density are considered to get determinate solutions of the field equations. We have shown that the components are not conserved separately because of mutual interaction between the two fluids, and the energy densities are proportional to 1/t2.

man with going on to perfection can be the symbol of the names of Allah (Asmaa’ul Allah) and the vicegerent of God on earth. The holy Quran in Baqarah chapter, verses 30-33, has presented the man’s capacity to achieve the position of the vicegerent of God on earth. In these verses, Allah announces to the angels that He has appointed a vicegerent on earth with the creation of man and afterwards in order to clarify the position of the vicegerent of God on earth, He mentions that vicegerent of God on earth is who has the knowledge to the names of Allah (Asmaa’ul Allah). Therefore, there is a close and deep relationship between the knowledge of man to the names of Allah and the vicegerent of God on earth. The exegetes have determined several attitudes for the meaning of the names of Allah and how to achieve its knowledge. Mulla Sadra in his interpretation for this verse believes that the meaning of teaching the names of Allah (Asmaa’ul Allah) to Adam (peace be upon him) is the manifestation of man for the names and attributes of Allah and comprehending all man’s knowledge and shows that how man’s universality can make him be worthy of being the vicegerent on earth and achieving to the position of and COSMIC Guardianship (Vellayat Takvini - Creational Guardianship).