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Dārjiling, India

Tamang A.,Darjeeling Government College | Potapov A.A.,Bashkir State University | Lukmanova R.,M. Akmullah Bashkir State Pedagogical University | Izmailov R.,M. Akmullah Bashkir State Pedagogical University | Nandi K.K.,North Bengal University
Classical and Quantum Gravity | Year: 2015

In this paper, we wish to investigate certain observable effects in the recently obtained wormhole solution of the Eddington-inspired Born-Infeld (EiBI) theory, which generalizes the zero-mass Ellis-Bronnikov wormhole of general relativity. The solutions of EiBI theory contain an extra parameter κ having the inverse dimension of the cosmological constant Λ, and which is expected to modify various general relativistic observables such as the masses of wormhole mouths, tidal forces and light deflection. A remarkable result is that a non-zero κ could prevent the tidal forces in the geodesic orthonormal frame from becoming arbitrarily large near a small throat radius (r0 ∼0) contrary to what happens near a small Schwarzschild horizon radius (M∼0). The role of κ in the flare-out and energy conditions is also analyzed, which reveals that the energy conditions are violated. We show that the exotic matter in the EiBI wormhole cannot be interpreted as a phantom (ω = pr/ρ <-1) or ghost field φ of general relativity due to the fact that both ρ and p r are negative for all κ. © 2015 IOP Publishing Ltd. Source

Pandit D.,Variable Energy Cyclotron Center | Mukhopadhyay S.,Variable Energy Cyclotron Center | Bhattacharya S.,Darjeeling Government College | Pal S.,Variable Energy Cyclotron Center | And 2 more authors.
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2010

The energy spectrum of the high energy γ-rays in coincidence with the prompt γ-rays has been measured for the spontaneous fission of 252Cf. The nucleus-nucleus coherent bremsstrahlung of the accelerating fission fragments is observed and the result has been substantiated with a theoretical calculation based on the Coulomb acceleration model. The width of the giant dipole resonance (GDR) decay from the excited fission fragments has been extracted for the first time and compared with the thermal shape fluctuation model (TSFM) in the liquid drop formalism. The extracted GDR width is significantly smaller than the predictions of TSFM. © 2010 Elsevier B.V. All rights reserved. Source

Chakraborty S.,Darjeeling Government College | Ray M.,University of Calcutta | Ray S.,University of Calcutta
Fish and Shellfish Immunology | Year: 2010

Toxicity of arsenic was investigated in the gill of Lamellidens marginalis by exposing the animals to sublethal concentrations of sodium arsenite for a maximum period of 30 days in controlled laboratory conditions. Arsenite exposure inhibited the activities of acid phosphatase (ACP), alkaline phosphatase (ALP), glutamate oxaloacetate transaminase (GOT), glutamate pyruvate transaminase (GPT) and acetlycholinesterase (AChE) in a dose and time dependent manner. Depletion in cytotoxic molecule like nitric oxide (NO) and suppression of phenoloxidase (PO) activity suggests an immune compromise in the animal. Inhibition in the activities of glutathione-s-transferase (GST) and catalase (CAT) in the species indicate impairment of its vital detoxification process and elevated oxidative stress respectively. Histopathology of the gill indicates arsenite induced damage of the organ leading to its possible dysfunction. The toxic exposure ravaged the structure and impaired the functions of the gill of the animal which might restrict its proper gaseous exchange, filter feeding and elicitation of immune responses against pathogens. © 2010 Elsevier Ltd. Source

This study, based on an investigation of morphology (as assessed through field and herbarium studies), leaf anatomy (stomata and vein islets), and pollen morphology (LM and SEM) reveals that Gaultheria stapfiana Airy Shaw is a distinct species and not a variant within of the G. hookeri C.B.Clarke as proposed by Ruizheng & P.F. Stevens (2005). Line drawings, photographs of living plants and specimens, photographs of leaf anatomical characters, and pollen of G. stapfiana and its allies, show that this species is clearly delimited from both G. hookeri and G. fragrantissima Wall. © 2012 Magnolia Press. Source

Panda S.,Darjeeling Government College
Journal of Japanese Botany | Year: 2012

The genus Diplarche Hook. f. & Thomson (Ericaceae) is recorded for the first time from Arunachal Himalaya, India. The genus comprises two species in the world, of which D, multiflora Hook, f. & Thomson is recorded based on the Kingdon-Ward collection from Arunachal Pradesh. The species is described here along with photographs of the herbarium specimen to facilitate identification in the field. Source

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