278 research outputs found
Strings with a confining core in a Quark-Gluon Plasma
We consider the intersection of N different interfaces interpolating between
different 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. 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 symmetry may still be
meaningful, with quark contributions leading to explicit breaking of this
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
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
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
Nanoparticle-Mediated Photodynamic Therapy for Mixed Biofilms
Wounds associated with diabetes are difficult to heal and often stay unhealed, leading to higher morbidity and mortality in the diabetic population. A major barrier to the successful healing of chronic diabetic wounds is the presence of biofilm-mediated infections. In recent years, photodynamic therapy (PDT) has emerged as a promising treatment modality for the management of chronic wounds. The objective of the present study was to evaluate the effectiveness of toluidine blue- (TB-) loaded nanoparticle-mediated PDT in eradicating antibiotic-resistant polymicrobial biofilms of Pseudomonas aeruginosa and methicillin-resistant Staphylococcus aureus in an in vitro model. Dioctyl sodium sulfosuccinate (aerosol OT, AOT)-alginate nanoparticles with high TB loading (10.8±2.2%) were formulated using a double emulsification cross-linking method. TB nanoparticles induced effective killing of planktonic P. aeruginosa (3.5 log10 CFU) and S. aureus (>5 log10 CFU) and their combined biofilms (2.8 log10 CFU for P. aeruginosa versus 3.4 log10 CFU for S. aureus). While P. aeruginosa biofilm was more resistant when compared to that of S. aureus, our results demonstrated effective eradication of complex biofilms of dual bacterial strains in vitro
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
Analysis of Flow Fields in a Flexible Tube with Periodic Constriction
Numerical techniques based on pressure-velocity formulation have been adopted to solve approximately, the governing equations for viscous flows through a tube (simulating an artery) with a periodic constriction. The effect of the constriction as well as the rigid of the tube, on the flow characteristics, and its consequences for arterial disease is the focus of this investigation. The unsteady incompressible Navier-Stokes equations are solved by using the finite-difference technique in staggered grid distribution. The haemodynamic factors like wall shear stress, pressure and velocity are analyzed through their graphical representations. Maximum resistance is attained in case of rigid stenosed tube rather than the flexible one. The main result is to contribute that the recirculating region is larger in case of a rigid tube than that of flexible one
Soil Quality Parameters and Carbon Stock as Influenced by Fodder Grasses and Organic Amendments in an Alfisol of Northeastern India
Intensive tillage, cultivation along the slope, low input, minimal nutrient replacement and high rainfall are among major causes of land degradation in the north eastern hill (NEH) region (Ghosh et al. 2009). Maintaining and enhancing soil quality are crucial to sustaining agricultural productivity and environmental quality (Lal, 2004). Continuous cropping, without use of conservation-effective measures, has negative effects on the soil and environment (e.g., loss of SOC, soil erosion, water pollution). Thus, soil management methods are needed that enhance use efficiency of inputs, reduce losses and minimize adverse impacts on the environment (Bilalis et al. 2009). Perennial grasses provide year- round ground cover, which reduces run-off and soil erosion from sloping land (Ghosh et al. 2009).
Cultivation of forages in degraded and sloping lands not only supply green palatable fodders to livestocks but also rehabilitates the degraded soils by improving physico-chemical properties. Forages have strong root systems compared to field crops (such as rice, maize etc.), protect soil and improve aggregation (Ghosh et al. 2009). Soils under perennial grasses and those which are undisturbed for a long time are potential C sinks because the grasses add organic matter (OM) to soils through root growth, and decline in OM decomposition because of lack of tillage. Further, conversion of degraded cropland soils to forages and perennial grasses lead to C sequestration (Grandy and Robertson, 2007).
Thus, present investigation was conducted with the objective to assess the impact of perennial forage grasses and organic amendments on soil properties and C-sequestration potential
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