Neutrino coupling to cosmological background: A review on gravitational Baryo/Leptogenesis

In this work we review the theories of origin of matter-antimatter asymmetry in the Universe. The general conditions for achieving baryogenesis and leptogenesis in a CPT conserving field theory have been laid down by Sakharov. In this review we discuss scenarios where a background scalar or gravitational field spontaneously breaks the CPT symmetry and splits the energy levels between particles and anti-particles. Baryon or Lepton number violating processes in proceeding at thermal equilibrium in such backgrounds gives rise to Baryon or Lepton number asymmetry.Comment: 62 pages, no figures. Invited review to appear in IJMP

Leptogenesis from Spin-Gravity Coupling Following Inflation

The energy levels of the left and the right handed neutrinos is split in the background of gravitational waves generated during inflation which in presence of lepton number violating interactions gives rise to a net lepton asymmetry at equilibrium. Lepton number violation is achieved by the same dimension five operator which gives rise to neutrino masses after electro-weak symmetry breaking. A net baryon asymmetry of the same magnitude can be generated from this lepton asymmetry by electroweak sphaleron processes.Comment: Journal version (accepted for publication in Phys. Rev. Lett.

Total knee replacement: a randomized study of clonidine and dexmedetomidine used for epidural postoperative analgesia

Background: Epidural anaesthesia with adjuvant is the preferred method for intra and postoperative pain relief after total knee replacement surgeries   but search for ideal adjuvant for prolonging the duration of postoperative analgesia without any side effect goes on. This study was conducted to evaluate the onset, extent and duration of sensory and motor block and side effects of clonidine or dexmedetomidine when used as an adjuvant in epidural anaesthesia in total knee replacement.Methods: 60 patients of ASA status I and II, posted for total knee replacement were randomly allocated into two groups of 30 each. Group I group patients received 18 ml of 0.5% levobupivacaine and clonidine 2 mcg/kg in epidural route and Group II group patients received 18 ml of 0.5% levobupivacaine and dexmedetomidine 1.5 mcg/kg in epidural route. Intraoperative and postoperative block characteristics as well as hemodynamic parameters were observed and recorded.Results: Dexmedetomidine had an earlier onset and longer duration of sensory and motor block in comparison to clonidine. Sedation scores were statistically significant with dexmedetomidine group in comparison to clonidine group.Conclusions: Dexmedetomidine was a better than clonidine as an adjuvant to levobupivacaine in epidural anaesthesia in total knee replacement