Dynamical phase transition of a periodically driven DNA

Replication and transcription are two important processes in living systems. To execute such processes, various proteins work far away from equilibrium in a staggered way. Motivated by this, aspects of hysteresis during unzipping of DNA under a periodic drive in non-equilibrium conditions are studied. A steady state phase diagram of a driven DNA is proposed which is experimentally verifiable. As a two state system, we also compare the results of DNA with that of an Ising magnet under an asymmetrical variation of magnetic field.Comment: 8 pages, 6 figures, Accepted version in PR

Corrosion of Reinforced Concrete and Its Protection

Concrete is used as construction material in the form of plain or reinforced concrete through out the world. It has to withstand the physical, chemical and environmental effects for fulfilling the durability characteristics. The environmental changes due to pollution, lack of main-tenance, poor quality of work, lack of supervision, use of defective materials etc have also taken a heavy toll of concrete structures. Among various factors affecting the reinforced concrete structures the atmosphere, water, salts are most common factors which play a key role for reinforcement corrosion. The damage due to corrosion is a serious effect upon the mechanical properties of concrete structures. Once the corrosion of reinforcement starts due to formation of oxide and if the structure is under load, the stress act-ing on it increases. In such case the ultimate tensile stress (UTS) exceeds and finally the structure fails. The present paper highlights the corrosion of rein-forced concrete structures, factors influencing corrosion of reinforcement, and its remedial measures to some extent

Zeno blocking of interplanar tunneling by intraplane inelastic scattering in layered superconductors: a generalized spin-boson analysis

Following an earlier proposal that the observed temperature dependence of the normal-state c-axis resistivity of oxide superconductors can be understood as arising from the inhibition of electron transport along the c axis due to in-plane incoherent inelastic scatterings suffered by the tagged electron, we consider a specific form for the interaction Hamiltonian. In this, the tagged electron is coupled to bosonic baths at adjacent planes (the baths at any two planes being uncorrelated) and is coupled also to the intraplane momentum-flip degree of freedom via the bath degrees of freedom. Thus our model Hamiltonian incorporates the earlier proposed picture that each in-plane inelastic scattering event is like a measurement of which plane the electron is in, and this, as in the quantum Zeno effect, leads to the suppression of interplane tunneling. In the present scenario it is the baths which bring about a coupling between the intraplane and interplane degrees of freedom. For simplicity we confine ourselves to dynamics in two adjacent planes and allow for two states only, as far as momentum flips due to scattering are concerned. In the case when the intraplane dynamics is absent, our model reduces effectively to the usual spin-boson model. We solve for the reduced tunneling dynamics of the electron using a non-Markovian master equation approach. Our numerical results on the survival probability of the electron in the initial plane show that the intraplane momentum flips lead to further inhibition of the interplane tunneling over and above the inhibition effected by pure spin-boson dynamics