Strings with a confining core in a Quark-Gluon Plasma

We consider the intersection of N different interfaces interpolating between different $Z_N$ vacua of an SU(N) gauge theory using the Polyakov loop order parameter. Topological arguments show that at such a string-like junction, the order parameter should vanish, implying that the core of this string (i.e. the junction region of all the interfaces) is in the confining phase. Using the effective potential for the Polyakov loop proposed by Pisarski for QCD, we use numerical minimization technique and estimate the energy per unit length of the core of this string to be about 2.7 GeV/fm at a temperature about twice the critical temperature. For the parameters used, the interface tension is obtained to be about 7 GeV/fm$^2$. Lattice simulation of pure gauge theories should be able to investigate properties of these strings. For QCD with quarks, it has been discussed in the literature that this $Z_N$ symmetry may still be meaningful, with quark contributions leading to explicit breaking of this $Z_N$ symmetry. With this interpretation, such {\it QGP} strings may play important role in the evolution of the quark-gluon plasma phase and in the dynamics of quark-hadron transition.Comment: 18 pages, 6 figures, RevTe

Genetic variability, characters association and path analysis for yield and fruit quality components in Brinjal

The experiment was done at AB District Seed Farm, BCKV, Kalyani Simanta, West-Bengal, India during autumn-winter 2013-14 and 2014-15. The characters that exhibited higher Phenotypic and Genotypic Co-efficient of variation values were number of fruits per plant (76.86, 75.63%), fruit weight (43.88, 41.34%), harvest index (23.57, 22.29%), fruit yield per plant (53.61, 51.17%), anthocyanin in peel, total phenols and DPPH (2,2-diphenyl-l-picryl hydrazyl) free radical scavenging (FRS) capacity indicating that a greater amount of genetic variability was present for these characters which provide greater scope for selection. High heritability coupled with high genetic advance as percent of mean was observed for the characters like plant height, days to 1st flowering, days to 50% flowering, number of fruits per plant, fruit weight, harvest index, fruit yield per plant, total sugar, anthocyanin in peel, total phenols and DPPH FRS capacity depicting that these traits were under the strong influence of additive gene action and hence simple selection based on phenotypic performance of these traits would be more effective. Fruit yield per plant showed highly positive significant correlation with number of primary branches per plant, number of fruits per plant, harvest index, vitamin-A and total phenols and significant negative correlation with days to 1st flowering, TSS, total sugars and total protein. Number of fruits per plant imparted the highest positive direct effect on yield followed by harvest index, fruit weight, days to 50% flowering and anthocyanin in peel. Number of fruits per plant and days to flowering were emerged as the main casual factors for positive or negative association of several characters with fruit yield per plant. Therefore, selection for fruit yield per plant based on these characters would be reliable

Site-specific spin crossover in Fe2_{2}TiO4_{4} post-spinel under high pressures to near a megabar

X-ray diffraction studies to ~90 GPa at room temperature show that Fe$_{2}$TiO$_{4}$ ferrous inverse spinel undergoes the following sequence of structural transitions : cubic (Fd3m) to tetragonal (I41/amd)to orthorhombic(Cmcm) to orthorhombic(Pmma),at the indicated onset transition pressures. Within the Cmcm phase, site-specific spin crossover is initiated and involves only highly distorted octahedral sites constituting ~25% of all Fe locations. This is manifest as a steeper volume decrease of dV/V0 ~ 3.5% beyond ~40 GPa and an emergent diamagnetic component discerned in 57Fe M\"ossbauer spectroscopy at variable cryogenic temperatures. A subsequent Cmcm to Pmma Fe/Ti disorder-order reconfiguration is facilitated at 6-fold coordinated (octahedral) sites. The rest of the high-spin Fe in 6-fold and 8-fold coordinated sites (~75% abundance) in the Pmma phase exhibit average saturation internal magnetic fields of H$_{hf}$ ~ 42 T to ~90 GPa, typical of spin-only (orbitally quenched) Fermi-contact values. By contrast average H$_{hf}$ ~ 20 T values, signifying unquenched orbital moments, occur below the 40-45 GPa spin-crossover initiation regime in the Cmcm phase. Therefore site-specific spin crossover invokes a cooperative lattice response and polyhedral distortions at the rest of the high-spin Fe sites, translating to 3d level (sub-band) changes and consequential orbital moment quenching. Near ~90 GPa Fe$_{2}$TiO$_{4}$ is a partially spin-converted chemically ordered Pmma post-spinel structure having a persistent charge gap of ~100 meV. Despite structural symmetry changes, partial spin crossover and lattice compressibility resulting in a ~33% total reduction in unit-cell volume and corresponding 3d bandwidth broadening, strong electron correlations persist at high densification.Comment: 35 Pages and 7 Figure

Baryon inhomogeneity generation via cosmic strings at QCD scale and its effects on nucleosynthesis

We have earlier shown that cosmic strings moving through the plasma at the time of a first order quark-hadron transition in the early universe can generate large scale baryon inhomogeneities. In this paper, we calculate detailed structure of these inhomogeneities at the quark-hadron transition. Our calculations show that the inhomogeneities generated by cosmic string wakes can strongly affect nucleosynthesis calculations. A comparison with observational data suggests that such baryon inhomogeneities should not have existed at the nucleosynthesis epoch. If this disagreement holds with more accurate observations, then it will lead to the conclusions that cosmic string formation scales above $10^{14} - 10^{15}$ GeV may not be consistent with nucleosynthesis and CMBR observations. Alternatively, some other input in our calculation should be constrained, for example, if the average string velocity remains sufficiently small so that significant density perturbations are never produced at the QCD scale, or if strings move ultra-relativistically so that string wakes are very thin, trapping negligible amount of baryons. Finally, if quark-hadron transition is not of first order then our calculations do not apply.Comment: 24 pages, 5 figures, minor changes, version to appear in Phys. Rev.

Measuring Cosmic Defect Correlations in Liquid Crystals

From the theory of topological defect formation proposed for the early universe, the so called Kibble mechanism, it follows that the density correlation functions of defects and anti-defects in a given system should be completely determined in terms of a single length scale $\xi$, the relevant domain size. Thus, when lengths are expressed in units of $\xi$, these distributions should show universal behavior, depending only on the symmetry of the order parameter, and space dimensions. We have verified this prediction by analyzing the distributions of defects/anti-defects formed in the isotropic-nematic phase transition in a thin layer of nematic liquid crystals. Our experimental results confirm this prediction and are in reasonable agreement with the results of numerical simulations.Comment: 15 pages, 4 figures, minor changes, few new references adde

Numerical Modeling of a Stenosed Artery Using Mathematical Model of Variable Shape

The intention of the present work is to carry out a systematic analysis of flow behavior in a two-dimensional tube (modeled as artery) with a locally variable shaped constrictions. The simulated artery, containing a viscous incompressible fluid representing the flowing blood, is treated to be complaint as well as rigid tube. The shape of the stenosis in the arterial lumen is chosen to be symmetric as well as asymmetric about the middle cross section perpendicular to the axis of the tube in order to improve resemblance to the in-vivo situation. The constricted tube is transformed into a straight tube and the resulting governing equations are solved by a numerical method with Reynolds number and ‘n’, a number giving the shape of the constriction as parameters. The influences of these parameters on the haemodynamic factors like wall shear stress, pressure and velocity have been analyzed. The present findings demonstrate that the flow resistance decreases as the shape of a smooth stenosis changes and maximum resistance is attained in case of a symmetric stenosis. But the length of separation increases in case of asymmetric constrictions and the oscillation in the shear layer appears earlier in case of asymmetric constriction than that in the case of symmetric constriction. Maximum resistance is attained in case of rigid stenosed tube rather than the flexible one

Cosmic string induced sheet like baryon inhomogeneities at quark-hadron transition

Cosmic strings moving through matter produce wakes where density is higher than the background density. We investigate the effects of such wakes occurring at the time of a first order quark-hadron transition in the early universe and show that they can lead to separation of quark-gluon plasma phase in the wake region, while the region outside the wake converts to the hadronic phase. Moving interfaces then trap large baryon densities in sheet like regions which can extend across the entire horizon. Typical separation between such sheets, at formation, is of the order of a km. Regions of baryon inhomogeneity of this nature, i.e. having a planar geometry, and separated by such large distance scales, appear to be well suited for the recent models of inhomogeneous nucleosynthesis to reconcile with the large baryon to photon ratio implied by the recent measurements of the cosmic microwave background power spectrum.Comment: 8 pages, 3 figure

Effects of Suction and Blowing on Flow Separation in a Symmetric Sudden Expanded Channel

A numerical simulation has been carried out to study the laminar flow in a symmetric sudden expanded channel subjected to a uniform blowing/suction speed placed at the lower and upper porous step walls. The governing equations for viscous flow have been solved using finite-difference techniques in pressure-velocity formulation. The results obtained here have been compared with the available experimental and numerical results of similar problems. It is noted that the recirculating region formed near the step walls diminishes in its length for increasing values of blowing speed applied at the porous step walls. For a suitable blowing speed, the recirculation zone disappears completely. The critical Reynolds number for the flow bifurcation (i.e. flow asymmetry) is obtained and it increases with the increase of the blowing speed. The critical Reynolds number for symmetry breaking of the flow decreases with the increasing values of suction speeds. The primary and the secondary recirculating regions formed near the channel walls are controlled using blowing