The Holography Hypothesis in Pre-Big-Bang Cosmology with String Sources

The holographic ratio in Pre-big bang string cosmology is obtained in the presence string sources. An iterative procedure is adopted to solve the equations of motion and derive the ratio in four dimensional world. First the zeroth order ratio is computed in the remote past, i.e. at $t=-\infty$, then the holographic ratio is obtained taking into account the evolution of the backgrounds following the iterative procedure. The corrections to the zeroth order value of the ratio depends on the form of the initial number distribution of the strings chosen. Moreover, we estimate the holographic ratio in the recent past (i.e. when $\gamma=-\frac{1}{d}$) and in the remote past (i.e. when $\gamma= 0$), $\gamma\equiv\frac{p}{\varrho}$, in different dimensions in the Einstein frame and in the string frame. We find that in the first case it has similar time dependences in both the frames, especially in four dimensions the ratio is explicitly computed to be the same in the two cases, whereas for $\gamma=0$ case the time dependence is different.Comment: 33 pages, latex, five figure

Perfect Teleportation and Superdense Coding With W-States

True tripartite entanglement of the state of a system of three qubits can be classified on the basis of stochastic local operations and classical communications (SLOCC). Such states can be classified in two categories: GHZ states and W-states. It is known that GHZ states can be used for teleportation and superdense coding, but the prototype W-state cannot be. However, we show that there is a class of W-states that can be used for perfect teleportation and superdense coding.Comment: 9 pages, no figur

Low-energy quenching of positronium by helium

Very low-energy scattering of orthopositronium by helium has been investigated for simultaneous study of elastic cross section and pick-off quenching rate using a model exchange potential. The present calculational scheme, while agrees with the measured cross section of Skalsey et al, reproduces successfully the parameter ^ 1Z_{\makebox{eff}}, the effective number of electrons per atom in a singlet state relative to the positron. Together with the fact that this model potential also leads to an agreement with measured medium energy cross sections of this system, this study seems to resolve the long-standing discrepancy at low energies among different theoretical calculations and experimental measurements.Comment: 4 latex pages, 3 postscript figure

Meteorological observations required for future weather modification programs

Meteorological observations required for computer models describing weather modification experiment

Self-Gravitational Corrections to the Cardy-Verlinde Formula and the FRW Brane Cosmology in SdS_5 Bulk

The semiclassical corrections to the Cardy-Verlinde entropy of a five-dimensional Schwarzschild de-Sitter black hole (SdS_5) are explicitly evaluated. These corrections are considered within the context of KKW analysis and arise as a result of the self-gravitation effect. In addition, a four-dimensional spacelike brane is considered as the boundary of the SdS_5 bulk background. It is already known that the induced geometry of the brane is exactly given by that of a radiation-dominated FRW universe. By exploiting the CFT/FRW-cosmology relation, we derive the self-gravitational corrections to the first Friedmann-like equation which is the equation of the brane motion. The additional term that arises due to the semiclassical analysis can be viewed as stiff matter where the self-gravitational corrections act as the source for it. This result is contrary to standard analysis that regards the charge of SdS_5 bulk black hole as the source for stiff matter. Furthermore, we rewrite the Friedmann-like equation in a such way that it represents the conservation equation of energy of a point particle moving in a one-dimensional effective potential. The self-gravitational corrections to the effective potential and, consequently, to the point particle's motion are obtained. A short analysis on the asymptotic behavior of the 4-dimensional brane is presented.Comment: 16 pages, LaTeX; (v2) references added and correcte

Role of Characterisation in Mineral Seperation by Froth Flotation

The paper emphasises the rationale behind characterisation in mineral separation by froth flotation . Inspite of the vital role of characterisation in mineral engineering, the entrire global effort in this area is weak. Without adeq-uate characterisation one can not understand the system under consideration and the reproducibility of the data collected in an incompletedly characterised system will be always questionable. The importance of characterisation in the context of froth flotation has been discussed under six headings namely, solid phase, aqueous phase including solutes, gas or the second liquid phase, the three kinds of interface & interline, flow & force parameters and end products. Exam-ples have been cited based on author's own work and also from literature

Minerals and their Exploitation in Ancient and Pre-modern India

The paper highlights the archaeological and literary evidence corroborating ancient India's primacy in the field of mineralogy and metallurgy. As we knew mineral is a naturally occuring crystalline element or a compound having definite chemical composition, and formed as a product of inorganic processes. The synthesis of new amorphous forms, biologically precipitated materials have put mineralogy at a cross-road. Both the scientist and archaeologists have legitimately taken broader interest in 'materials'. The paper gives stress on India's primacy in lapidary art, chalcedony, conch-shell, pearl, diamond, beryl, emerald, many other gems, and metallurgical prac-tices related to laminated and forged iron, brass, zinc, crucible steel. etc, Further, it has been attempted to trace the history, technology and occurrence of various minerals from evidence excavated by archeologists. The sample has been taken from the various periods right from pre-Harappan civilisation of India to modern India