Kinetics of Phase Transitions in Quark Matter

We study the kinetics of chiral transitions in quark matter using a phenomenological framework (Ginzburg-Landau model). We focus on the effect of inertial terms on the coarsening dynamics subsequent to a quench from the massless quark phase to the massive quark phase. The domain growth process shows a crossover from a fast inertial regime [with $L(t) \sim t (\ln t)^{1/2}$] to a diffusive Cahn-Allen regime [with $L(t)\sim t^{1/2}$].Comment: 17 pages with 4 figures. Published in Euro Physics Letters (EPL). arXiv admin note: substantial text overlap with arXiv:1209.6137, arXiv:1101.050

Ordering dynamics of self-propelled particles in an inhomogeneous medium

Ordering dynamics of self-propelled particles in an inhomogeneous medium in two-dimensions is studied. We write coarse-grained hydrodynamic equations of motion for coarse-grained density and velocity fields in the presence of an external random disorder field, which is quenched in time. The strength of inhomogeneity is tuned from zero disorder (clean system) to large disorder. In the clean system, the velocity field grows algebraically as $L_{\rm V} \sim t^{0.5}$. The density field does not show clean power-law growth; however, it follows $L_{\rm \rho} \sim t^{0.8}$ approximately. In the inhomogeneous system, we find a disorder dependent growth. For both the density and the velocity, growth slow down with increasing strength of disorder. The velocity shows a disorder dependent power-law growth $L_{\rm V}(t,\Delta) \sim t^{1/\bar z_{\rm V}(\Delta)}$ for intermediate times. At late times, there is a crossover to logarithmic growth $L_{\rm V}(t,\Delta) \sim (\ln t)^{1/\varphi}$, where $\varphi$ is a disorder independent exponent. Two-point correlation functions for the velocity shows dynamical scaling, but the density does not

Structural Basis for the Anomalously Low Spontaneous Polarisation Values of the Polar Phase of Sr1-xCaxTiO3 (x=0.02, 0.04): Evidence for a Ferrielectric Ordering

Full pattern Le-Bail refinement using x-ray powder diffraction profiles of Sr1-xCaxTiO3 for x=0.02, 0.04 in the temperature range 12 to 300 K reveals anomalies in the unit cell parameters at 170, 225 K due to an antiferrodistortive (cubic to tetragonal I4/mcm) phase transition and at ~32, ~34 K due to a transition to a polar phase (tetragonal I4/mcm to orthorhombic Ic2m), respectively. The lower transition temperatures obtained by us are in excellent agreement with those reported on the basis of the dielectric studies by Bednorz and Muller, [10] who attributed these to ferroelectric transition. Rietveld analysis of the diffraction profiles of the polar phase reveals off-centre displacements of both Sr2+/Ca2+ and Ti4+ ions in the X-Y plane along pseudocubic directions, in agreement with the experimentally reported direction of easy polarization by Bednorz and Muller, but the resulting dipole moments are shown to be ferrielectrically coupled in the neighbouring (001) planes along the [001] direction leading to anomalously low values of the spontaneous polarization at 12K.Comment: 5 pages, 4 figures and 1 tabl

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

Comparing the effects of alternate day and daily thyroxine replacement therapy in subclinical hypothyroidism

Background:  Subclinical hypothyroidism (SCH) is defined as serum thyroid-stimulating hormone (TSH) level above upper limit of normal despite normal levels of serum free thyroxine.  According to recommendations, L-thyroxine treatment for hormone replacement therapy should be continued on daily basis. However, some trials have challenged daily regimen for management of hypothyroidism and have suggested dosage scheduling at weekly, twice-a-week or alternate day as possible alternatives having similar effect as for daily regimen.Methods: Study was prospective randomized cross-over intervention design.  Thyroid functions (T3, T4 and TSH) were measured using third generation non-isotopic immunochemiluminescence method using standard protocol. 120 patients with clinically established hypothyroidism were enrolled in study.Results: Difference in mean TSH levels of group I and group II were not found to be statistically significant at baseline (8.247±2.288 mIU/ml versus 8.210±2.650; p=0.935), at 6 weeks (2.337±1.792 mIU/ml versus 2.843±2.410 mIU/ml; p=0.195) and at 12 weeks (2.508±1.180 mIU/ml versus 2.831±1.200 mIU/ml; p=0.191). Difference in mean T3 levels of group I and group II were not found to be statistically significant at baseline (1.118±0.199 ng/dl versus 1.184±0.187 ng/dl; p=0.061), at 6 weeks (1.266±0.295 ng/dl versus 1.196±0.289 ng/dl; p=0.192) and at 12 weeks (1.121±0.211 ng/dl versus 1.179±0.203 ng/dl; p=0.174). Difference in mean T4 levels group I and group II were not found to be statistically significant at baseline (8.422±2.054 µg/dl versus 7.899±2.333 µg/dl; p=0.196), at 6 weeks (8.852±2.836 µg/dl versus 8.533±2.672 µg/dl; p=0.527) and at 12 weeks (8.159±2.235 µg/dl versus 7.990±2.463 µg/dl; p=0.728).Conclusions: The findings of present study show that alternate day L-thyroxine is a viable solution for the management of SCH. 

Statistical Mechanics of DNA unzipping under periodic force: Scaling behavior of hysteresis loop

A simple model of DNA based on two interacting polymers has been used to study the unzipping of a double stranded DNA subjected to a periodic force. We propose a dynamical transition, where without changing the physiological condition, it is possible to bring DNA from the zipped/unzipped state to a new dynamic (hysteretic) state by varying the frequency of the applied force. Our studies reveal that the area of the hystersis loop grows with the same exponents as of the isotropic spin systems. These exponents are amenable to verification in the force spectroscopic experiments.Comment: Accepted for publication in Physical Review Letter