Electric and Magnetic fields due to Dirac particles in FRW spacetime

Some solutions of the Maxwell equations with Dirac particles for the source in FRW spacetime are discussed. The Green's function of the equation for the radial component of the Maxwell fields, F_{r\eta} and F_{\theta\phi} is solved. Green's function is found to reduce to that of Minkowskian spacetime in the appropriate limit. Also, the Lienard-Wiechert type solution is derived. Also, the solutions with the Dirac particle current is also presented. It is found that the F_{r\eta} is composed of even angular momentum states while the odd states constitue F_{\theta\phi} .Comment: 8 pages including 2 figure

Pharmacognostical and preliminary phytochemical screening of the corm of Stephania hernandifolia (Willd.) Walp.

The aim of the study is to cover the pharmacognostical and preliminary phytochemical screening of the corm of Stephania hernandifolia (Willd.) Walp. Stephania hernandifolia (Willd.) Walp. belonging to the family Menispermaceae is a natural taxon. The plant was collected from the Darjeeling district of West Bengal, India, during summer and was authenticated by the botanist. Pharmacognostical study included macroscopical characters, microscopical characters, physico-chemical constants and fluorescence analysis. Preliminary phytochemical screening includes phytochemical extraction, phytochemical testing and thin layer chromatography (TLC). In macroscopical studies of the corm, it was found that, it’s shape was spherical, size was about 8 to 20 cm in length and 10 to 20 cm broad, colour was brown (Rusty), surface was rough, odour was not specific, taste was bitter, direction of growth was vertical, the surface has many circular and slightly raised spots. In microscopical studies of corm, it were found that it has periderm, vascular bundles, thin phelloderm cells, ground parenchymatous cells, dense masses of starch grains and wide circular secretory cavities were seen. In powder microscopy, sclereids and vessel elements have been observed with short sclerenchyma. Physico-chemical parameters like total ash value (13 % w/w), acid insoluble ash value (2.66 %w/w), water-soluble ash value (2.50 %w/w) and sulphated ash value (3.33 %w/w) were observed. Alcohol soluble extractive value (7.23 %w/w), water-soluble extractive value (10.84 %w/w) were also observed and loss on drying was observed as 2.50 %w/w. The foaming index was found to be 111.11. Preliminary phytochemical studies show the presence of alkaloids, carbohydrates, Steroids, Saponin, tannin and phenolic compounds flavanoids, and lignin in ethanolic extract and carbohydrates, Saponin, tannin and phenolic compounds flavanoids, and lignin in aqueous extract. Performing TLC of ethanolic extract using chloroform: ethanol (30:70) and methanol: water (70: 30) as solvent system, few spots were identified. The study helps in the correct identification of the plant. The presence of alkaloids and flavanoids explains that the plant must have valuable medicinal properties which must be explored

Optimization of the level of ingredients for functional dairy beverage using response surface methodology (RSM)

The present investigation was undertaken to optimize the level of ingredients (milk fat, sugar, and mango pulp) for functional dairy beverage using Response Surface Methodology. Central Composite Rotatable Design with milk fat (%), sugar (%), and mango pulp (var. Chaunsa, %) as independent variables produced 20 different combinations that were used to investigate the effect on viscosity (cP), antioxidant activity, and overall acceptability. The response surface three dimensional graphs were plotted as a function of two variables to show the effect of level of ingredients on physico-chemical and sensory properties of the beverage. Significant correlation models were established with the coefficient of correlation (R2) greater than 0.8. An optimization of process variables was attempted for maximum antioxidant activity and overall acceptability. ANOVA tables revealed that increase in fat and sugar levels lowered the antioxidant activity, while enhancement of mango pulp significantly increased both antioxidant activity and overall acceptability of the beverage. The optimized levels of ingredients were 0.5% milk fat, 6.0% sugar and 30% mango pulp

Competing spin transfer and dissipation at Co/Cu(001) interfaces on femtosecond timescales

By combining interface-sensitive non-linear magneto-optical experiments with femtosecond time resolution and ab-initio time-dependent density functional theory, we show that optically excited spin dynamics at Co/Cu(001) interfaces proceeds via spin-dependent charge transfer and backtransfer between Co and Cu. This ultrafast spin transfer competes with dissipation of spin angular momentum mediated by spin-orbit coupling already on sub 100 fs timescales. We thereby identify the fundamental microscopic processes during laser-induced spin transfer at a model interface for technologically relevant ferromagnetic heterostructures.Comment: 5 pages, 4 figure

Semiclassical ordering in the large-N pyrochlore antiferromagnet

We study the semiclassical limit of the $Sp(N)$ generalization of the pyrochlore lattice Heisenberg antiferromagnet by expanding about the $N \to \infty$ saddlepoint in powers of a generalized inverse spin. To leading order, we write down an effective Hamiltonian as a series in loops on the lattice. Using this as a formula for calculating the energy of any classical ground state, we perform Monte-Carlo simulations and find a unique collinear ground state. This state is not a ground state of linear spin-wave theory, and can therefore not be a physical (N=1) semiclassical ground state.Comment: 4 pages, 4 eps figures; published versio

Strengthening of heat damaged reinforced concrete cylinders

The purpose of this study is to investigate the effectiveness of various strengthening techniques in restoring heat damaged reinforced concrete. A series of 40 reinforced concrete cylinders were tested under concentric compression after being jacketed externally with high strength fiber reinforced concrete (HSFRC), Ferrocement (FC) and Glass fiber reinforced polymer (GFRP) jackets. Concrete specimens were exposed to elevated temperatures ranging from room temperature to 900 ºC. The overall response of strengthened specimens was investigated vis-à-vis un-strengthened specimens in terms of axial compression, axial displacement and axial stress strain behaviour. The results indicate that important gains in strength and ductility can be achieved by strengthening heat – damaged R.C cylinders by HSFRC, FC and GFRP external Jacketing. GFRP jacketing was found to be the most effective method of strengthening fire or heat damaged concrete structures