Domain walls in Born-Infeld-dilaton background

We study the dynamics of domain walls in Einstein-Born-Infeld-dilaton theory. Dilaton is non-trivially coupled with the Born-Infeld electromagnetic field. We find three different types of solutions consistent with the dynamic domain walls. For every case, the solutions have singularity. Further more, in these backgrounds, we study the dynamics of domain walls. We qualitatively plot various form of the bulk metrics and the potential encountered by the domain walls. In many cases, depending upon the value of the parameters, the domain walls show bouncing universe and also undergo inflationary phase followed by standard decelerated expansion.Comment: 18 pages,6 figures,latex, References added, Some points clarifie

Correspondence between Electro-Magnetic Field and other Dark Energies in Non-linear Electrodynamics

In this work, we have considered the flat FRW model of the universe filled with electro-magnetic field. First, the Maxwell's electro-magnetic field in linear form has been discussed and after that the modified Lagrangian in non-linear form for accelerated universe has been considered. The corresponding energy density and pressure for non-linear electro-magnetic field have been calculated. We have found the condition such that the electro-magnetic field generates dark energy. The correspondence between the electro-magnetic field and the other dark energy candidates namely tachyonic field, DBI-essence, Chaplygin gas, hessence dark energy, k-essenece and dilaton dark energy have been investigated. We have also reconstructed the potential functions and the scalar fields in this scenario.Comment: 11 pages, 7 figure

Protection from experimental colitis by theaflavin-3,3'-digallate correlates with inhibition of IKK and NF-κB activation

Background and purpose: Inflammatory bowel disease (IBD) is associated with activation of nuclear factor κ B (NF-κB) involved in regulating the expression of inducible nitric oxide synthase (iNOS) and proinflammatory cytokine genes. As theaflavin-3,3'-digallate (TFDG), the most potent anti-oxidant polyphenol of black tea, down-regulates NF-κB activation, we investigated if TFDG is beneficial in colonic inflammation by suppressing iNOS and proinflammatory cytokines. Experimental approach: The in vivo efficacy of TFDG was assessed in mice with trinitrobenzene sulfonic acid (TNBS)-induced colitis. Both mRNA and protein levels of proinflammatory cytokines and iNOS were analyzed in colon tissue treated with or without TFDG. NF-κB activation was determined by electrophoretic mobility shift assay and levels of NF-κB inhibitory protein (IκBα) were analyzed by Western blotting. Key results: Oral administration of TFDG (5 mg kg-1 daily i.g.) significantly improved TNBS-induced colitis associated with decreased mRNA and protein levels of TNF-α, IL-12, IFN- and iNOS in colonic mucosa. DNA binding and Western blotting revealed increase in NF-κB activation and IκB depletion in TNBS-treated mice from Day 2 through Day 8 with a maximum at Day 4, which resulted from increased phosphorylation of IκB and higher activity of IκB kinase (IKK). Pretreatment with TFDG markedly inhibited TNBS-induced increases in nuclear localization of NF-κBα, cytosolic IKK activity and preserved IκBα in colon tissue. Conclusions and Implications: TFDG exerts protective effects in experimental colitis and inhibits production of inflammatory mediators through a mechanism that, at least in part, involves inhibition of NF-κB activation