8,736 research outputs found

    Role of Dream in Kui-Culture

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    The dream is a state of mind while asleep. It is a reflection of one's thought, imagination and intuition. Everybody, even a blind can have dreams. Dreams have influenced the lives of people since the beginning across civilisations in myriad ways. It is now part of the legend that Queen Mayadevi of King Sudhodan had a dream that an elephant is entering her body. To explain the dream the wise men of the royal court were consulted. The opinion was the queen would beget a son who has qualities of a superman, who can become a "chakravarti" or an ascetic. The Child became the Buddha, the enlightened one. Similarly, the Queen of Julius Caesar had a dram that the statue of Caesar in the market place is bleeding and she apprehended a danger to the life of her husband. It was for the dream; she pleaded Caesar not to go to the party by his friends in which Caesar was ultimately stabbed to death. In both the instances, the dreams were indicative of the coming events

    Dynamics of Magnetized Bulk Viscous Strings in Brans-Dicke Gravity

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    We explore locally rotationally symmetric Bianchi I universe in Brans-Dicke gravity with self-interacting potential by using charged viscous cosmological string fluid. We use a relationship between the shear and expansion scalars and also take the power law for scalar field as well as self-interacting potential. It is found that the resulting universe model maintains its anisotropic nature at all times due to the proportionality relationship between expansion and shear scalars. The physical implications of this model are discussed by using different parameters and their graphs. We conclude that this model corresponds to an accelerated expanding universe for particular values of the parameters.Comment: 17 pages, 6 figure

    Highly Excited Core Resonances in Photoionization of Fe XVII : Implications for Plasma Opacities

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    A comprehensive study of high-accuracy photoionization cross sections is carried out using the relativistic Breit-Pauli R-matrix (BPRM) method for (hnu + Fe XVII --> Fe XVIII + e). Owing to its importance in high-temperature plasmas the calculations cover a large energy range, particularly the myriad photoexciation-of-core (PEC) resonances including the n = 3 levels not heretofore considered. The calculations employ a close coupling wave function expansion of 60 levels of the core ion Fe XVIII ranging over a wide energy range of nearly 900 eV between the n = 2 and n = 3 levels. Strong coupling effects due to dipole transition arrays 2p^5 --> 2p^4 (3s,3d) manifest themselves as large PEC resonances throughout this range, and enhance the effective photoionization cross sections orders of magnitude above the background. Comparisons with the erstwhile Opacity Project (OP) and other previous calculations shows that the currently available cross sections considerably underestimate the bound-free cross sections. A level-identification scheme is used for spectroscopic designation of the 454 bound fine structure levels of Fe XVII. Level-specific photoionization cross sections are computed for all levels. In addition, partial cross sections for leaving the core ion Fe XVII in the ground state are also obtained. These results should be relevant to modeling of astrophysical and laboratory plasma sources requiring (i) photoionization rates, (ii) extensive non-local-thermodynamic-equilibrium models, (iii) total unified electron-ion recombination rates including radiative and dielectronic recombination, and (iv) plasma opacities. We particularly examine PEC and non-PEC resonance strengths and emphasize their expanded role to incorporate inner-shell excitations for improved opacities, as shown by the computed monochromatic opacity of Fe XVII.Comment: 12 pages, 5 figures, Physical Review A (in press

    Higher Dimensional Dust Cosmological Implications of a Decay Law for Λ\Lambda Term : Expressions for Some Observable Quantities

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    In this paper we have considered the multidimensional cosmological implications of a decay law for Λ\Lambda term that is proportional to ÎČaša\beta \frac{\ddot {a}}{a}, where ÎČ\beta is a constant and aa is the scale factor of RW-space time. We discuss the cosmological consequences of a model for the vanishing pressure for the case k=0k=0. It has been observed that such models are compatible with the result of recent observations and cosmological term Λ\Lambda gradually reduces as the universe expands. In this model Λ\Lambda varies as the inverse square of time, which matches its natural units. The proper distance, the luminosity distance-redshift, the angular diameter distance-redshift, and look back time-redshift for the model are presented in the frame work of higher dimensional space time. The model of the Freese {\it et al.} ({\it Nucl. Phys. B} {\bf 287}, 797 (1987)) for n=2n=2 is retrieved for the particular choice of A0A_{0} and also Einstein-de Sitter model is obtained for A0=2/3A_{0} = {2/3}. This work has thus generalized to higher dimensions the well-know result in four dimensional space time. It is found that there may be significant difference in principle at least, from the analogous situation in four dimensional space time.Comment: 10 pages, no figure, to be appear in IJMP

    Bianchi Type-II String Cosmological Models in Normal Gauge for Lyra's Manifold with Constant Deceleration Parameter

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    The present study deals with a spatially homogeneous and anisotropic Bianchi-II cosmological models representing massive strings in normal gauge for Lyra's manifold by applying the variation law for generalized Hubble's parameter that yields a constant value of deceleration parameter. The variation law for Hubble's parameter generates two types of solutions for the average scale factor, one is of power-law type and other is of the exponential form. Using these two forms, Einstein's modified field equations are solved separately that correspond to expanding singular and non-singular models of the universe respectively. The energy-momentum tensor for such string as formulated by Letelier (1983) is used to construct massive string cosmological models for which we assume that the expansion (Ξ\theta) in the model is proportional to the component σ 11\sigma^{1}_{~1} of the shear tensor σij\sigma^{j}_{i}. This condition leads to A=(BC)mA = (BC)^{m}, where A, B and C are the metric coefficients and m is proportionality constant. Our models are in accelerating phase which is consistent to the recent observations. It has been found that the displacement vector ÎČ\beta behaves like cosmological term Λ\Lambda in the normal gauge treatment and the solutions are consistent with recent observations of SNe Ia. It has been found that massive strings dominate in the decelerating universe whereas strings dominate in the accelerating universe. Some physical and geometric behaviour of these models are also discussed.Comment: 24 pages, 10 figure

    X-ray He-like ions diagnostics: New Computations for Photoionized Plasmas: I. preliminary considerations

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    Using the new version of the photoionization code Titan designed for plane-parallel photoionized thick hot media, which is unprecedented from the point of view of line transfer, we have undertaken a study of the influence of different parameters on the He-like and H-like emission of a medium photoionized by an X-ray source. We explain why in modelling the emitting medium it is important to solve in a self-consistent way the thermal and ionization equilibria and to take into account the interconnection between the different ions. We give the equivalent widths of the sum of the He-like triplets and the triplet intensity ratios GG and RR, for the most important He-like ions, for a range of density, column density, and ionization parameter, in the case of constant density media. We show that the line intensities from a given ion can be accounted for, either by small values of both the column density and of the ionization parameter, or by large values of both quantities, and it is necessary to take into account several ions to disentangle these possibilities. We show also that a "pure recombination spectrum" almost never exists in a photoionized medium: either it is thin, and resonance lines are formed by radiative excitation, or it is thick, and free-bound absorption destroys the resonance photons as they undergo resonant diffusion.Comment: 19 pages, 14 figures, accepted in A &

    Bianchi Type I Magnetofluid Cosmological Models with Variable Cosmological Constant Revisited

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    The behaviour of magnetic field in anisotropic Bianchi type I cosmological model for bulk viscous distribution is investigated. The distribution consists of an electrically neutral viscous fluid with an infinite electrical conductivity. It is assumed that the component σ11\sigma^{1}_{1} of shear tensor σij\sigma^{j}_{i} is proportional to expansion (Ξ\theta) and the coefficient of bulk viscosity is assumed to be a power function of mass density. Some physical and geometrical aspects of the models are also discussed in presence and also in absence of the magnetic field.Comment: 13 page
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