Bulk Viscosity

Sucralose is a commonly employed artificial sweetener that behaves very differently than its natural disaccharide counterpart, sucrose, in terms of its interaction with biomolecules. The presence of sucralose in solution is found to destabilize the native structure of two model protein systems: the globular protein bovine serum albumin and an enzyme staphylococcal nuclease. The melting temperature of these proteins decreases as a linear function of sucralose concentration. We correlate this destabilization to the increased polarity of the molecule. The strongly polar nature is manifested as a large dielectric friction exerted on the excited-state rotational diffusion of tryptophan using time-resolved fluorescence anisotropy. Tryptophan exhibits rotational diffusion proportional to the measured bulk viscosity for sucrose solutions over a wide range of concentrations, consistent with a Stokes-Einstein model. For sucralose solutions, however, the diffusion is dependent on the concentration, strongly diverging from the viscosity predictions, and results in heterogeneous rotational diffusion.

The Fractal-Hue Quantum Field Theory (FHQFT) introduces a recursive, multi-scale framework for modeling quantum fields as fractal-holographic entities embedded in hue-stratified manifolds. Unlike conventional field theories constrained by integer-dimensional topologies, FHQFT leverages spectral projectors, UV-regularized hue gradients, and nonlocal coherence structures to encode field dynamics across nested scales. The theory integrates Dirac and Klein-Gordon solvers modulated by hue parameters, enabling novel interpretations of spinor behavior, entropy stratification, and renormalization flows.

FHQFT predicts emergent holographic dualities and topological transitions governed by fractal Laplacians and entropy-weighted projector dynamics, offering a generative model for quantum entanglement, anomaly resolution, and field localization. Its recursive geometry supports both phenomenological applications and abstract topological classifications, bridging the gap between high-energy physics and geometric field theory. The framework is poised to redefine foundational approaches to quantum coherence, holography, and the structure of spacetime.

We study vacuum fluctuation properties of an ensemble of SU(N) gauge theory configurations, in the limit of many colors, viz. N c → ∞, and explore the statistical nature of the topological susceptibility by analyzing its critical behavior at a non-zero-vacuum parameter θ and temperature T. We find that the system undergoes a vacuum phase transition at the chiral symmetry restoration temperature as well as at an absolute value of θ. On the other hand, the long-range correlation length solely depends on θ for the theories with critical exponent e = 2 or T = T d + 1, where T d is the decoherence temperature. Furthermore, it is worth noticing that the unit-critical exponent vacuum configuration corresponds to a non-interacting statistical basis pertaining to a constant mass of η .

We investigate the effects of the accretion of phantom energy with non-zero bulk viscosity onto a Schwarzschild black hole and show that black holes accreting viscous phantom energy will lose mass rapidly compared to the non-viscous case. When matter is incorporated along with the phantom energy, the black holes meet with the same fate as bulk viscous forces dominate matter accretion. If the phantom energy has large bulk viscosity, then the mass of the black hole will reduce faster than in the small viscosity case.

In the present study, we have investigated inflationary cosmological model with flat potential and bulk viscosity taking Bianchi Type VI 0 space-time as a source. To get the deterministic model of universe, we have also assumed that shear () is proportional to expansion () (Thorne [31]) and  = constant as considered by Zimdahal [29] where  is the coefficient of bulk viscosity. We find that the observations of inflationary cosmology i.e. slow role parameters (,), third slow parameter (S) and anisotropic parameter (Ã m ) are in excellent agreement with the Planck ( ) results [39]. We also find that spatial volume increases exponentially representing inflationary scenario of the universe. The model in general represents anisotropic space time but isotropizes when n = 1. The model also represents accelerating and decelerating phases of universe which matches with latest observations of universe. The rate of Higgs field is initially large but decreases with time and vanishes for large value of time. The model has Point Type singularity at T = 0 (MacCallum [30]).

In the present work, we analyzed the Kantowski-Sachs cosmological model and teleparallel gravity, where a bulk viscous fluid containing one-dimensional cosmic strings is the source for the energy−momentum tensor. To obtain the deterministic solution of the field equations, we employed the proportionality condition linking the shear scalar (σ) and the expansion scalar (θ), establishing a relationship between metric potentials. Another approach employed is the hybrid expansion law (HEL). The discussion focuses on the behavior of the accelerating universe concerning the specific choice of a nonlinear (or power law model) of teleparallel gravity f (T) = αT + βT m , where T is the torsion scalar, α , and β are model parameters and m is restricted to greater than or equal to 2. The effective equation of the state parameter (ω e f f) of models will support the acceleration of the universe. We observed that the null and weak energy conditions are obeyed but violate the strong energy condition as per the present accelerating expansion. Under specific model parameter constraints, the universe shows a transition from a decelerating to an accelerating phase.

We have investigated an inhomogeneous Bianchi type-I cosmological model with electromagnetic field based on Lyra geometry. A new class of exact solutions have been obtained by considering the potentials of metric and displacement field are functions of coordinates t and x. The physical behavior of the obtained model is discussed.

NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0). You must give appropriate credit to authors and reference this article if parts of the article are reproduced in any manner. Applicable licensing terms are at https://creativecommons. org/licenses/by-nc-nd/4.0/. Global Journal of Science Frontier Research: F Mathematics and Decision Sciences Volume 22 Issue 1 Version 1.0 Year 2022 Type : Double Blind Peer Reviewed International Research Journal Publisher: Global Journals Online ISSN: 2249-4626 & Print ISSN: 0975-5896

By considering f (R) gravity models, the cosmic evolution is modified with respect to the standard ΛCDM scenario. In particular, the thermal history of particles results modified. In this paper, we derive the evolution of relics particles (WIMPs) assuming a reliable f (R) cosmological solution and taking into account observational constraints. The connection to the PAMELA experiment is also discussed. Results are consistent with constraints coming from BICEP2 and PLANCK experiments.

Bianchi type-V cosmological model along with perfect fluid and heat conduction have been discussed in the presence of Lyra's geometry. By using the law of variation for the mean Hubble parameter the solution contains heat conduction and gauge function for and , which is related to the average scale factor of metric factor of metric and gives decelerating parameter. We discussed heat transmission stages from initial time to the late time of the universe. The relation between density and pressure is discussed. We obtain a constant decelerating parameter. Physical interpretation and thermodynamic laws are discussed.

Bianchi type-I magnetized cosmological models with time-dependent gauge function β for stiff fluid distribution within the framework of Lyra geometry are investigated. To get the deterministic model of the universe, we have assumed that eigenvalue (σ 1 1) of shear tensor (σ j i) is proportional to the expansion (θ). This leads to A = (BC) n where A, B and C are metric potentials. The physical and geometrical aspects of the models and singularities in the models are discussed.

The diploma thesis deals with pressure pulsations in pipeline system with dynamic muffler. There is presented original geometry of side-branch resonator. Pressure pulsations are solved by a created mathematical model, numerical simulations and verified by an experimental approach. The influence of dynamic and bulk viscosity is involved in derived governing equations. A system of nonlinear equations is solved by genetic algorithm and frequency dependent relationship of bulk viscosity of air is determined afterwards. The correct function of used pressure sensors is tested. The processing of experimental data is performed by the fast Fourier transform with coherent sampling. Finally, a comparison of analytical, numerical and experimental approaches is introduced for different geometric variants of presented muffler

The present study deals with the Bianchi type-III cosmological model with special form of deceleration parameter in presence of perfect fluid in f(R, T) theory of gravity proposed by Harko et al.(2011). The solutions of the field equations have been obtained by applying the law of special form deceleration parameter proposed by Singha and Debnath (2009). The physical and geometrical parameters of the model are obtained and discussed in details.

In this paper, Bianchi type–III dark energy model with variable equation of state (EοS) has been investigated in scale covariant theory of gravitation formulated by Canuto et al. (Phys. Rev. Lett. 39: 429, 1977). Special law of Hubble parameter proposed by Bermann (Nuovo-Cimento 74; 182, 1983) being incorporated to obtain the solutions of field equations. Some physical properties of the model are also discussed.

In this paper we are to study homogeneous and anisotropic Bianchi type-V universe in presence of viscous fluid as source of matter with time function gravitational constant G and cosmological term . The viscosity coefficient is regarded as a power function of matter density in the first case whereas in other case it is considered as proportional to scale of expansion. Physically realistic solutions of the field equations are obtained by using a fractional form of Hubble's parameter, which leads an early deceleration and late time acceleration of the universe. Certain physical and geometrical behaviors of the models are also studied.

We analyze late-time evolution of the Universe in the framework of the self-consistent model, in which the dark matter is influenced by the Archimedean-type force proportional to the four-gradient of the dark energy pressure. The dark energy is considered as a fluid with the equation of state of the relaxation type, which takes into account a retardation of the dark energy response to the Universe accelerated expansion. The dark matter is guided by the Archimedean-type force, which redistributes the total energy of the dark fluid between two its constituents, dark energy and dark matter, in the course of the Universe accelerated expansion. We focus on the constraints for the dark energy relaxation time parameter, for the dark energy equation of state parameter, and for the Archimedean-type coupling constants, which guarantee the Big Rip avoidance. In particular, we show that the Archimedean-type coupling protects the Universe from the Big Rip scenario with asymptotically infinite negative dark energy pressure, and that the Little Rip is the fate of the Universe with the Archimedean-type interaction inside the dark fluid.

The effect of bulk viscosity on the evolution of the spatially flat Friedmann–Lemaitre–Robertson–Walker (FLRW) models in the context of open thermodynamical systems, which allow for particle creation, is analysed within the framework of Brans–Dicke (BD) theory. The BD field equations are modified with the incorporation of a creation pressure and bulk viscous stress. A class of physically plausible models has been taken into consideration. The behaviour of the particle number density and bulk viscosity is discussed with the evolution of the Brans–Dicke scalar field.

The present study deals with spatially homogeneous and totally anisotropic locally rotationally symmetric (LRS) Bianchi type I cosmological model with variable G and Λ in presence of imperfect fluid. To get the deterministic model of Universe, we assume that the expansion (θ) in the model is proportional to shear (σ). This condition leads to A = ℓB n , where A, B are metric potential. The cosmological constant Λ is found to be decreasing function of time and it approaches a small positive value at late time which is supported by recent Supernovae Ia (SN Ia) observations. Also it is evident that the distance modulus curve of derived model matches with observations perfectly.

In this paper we discuss the law of variation of scale factor a = (t k e t) 1 n which yields a time-dependent deceleration parameter (DP) representing a new class of models that generate a transition of universe from the early decelerated phase to the recent accelerating phase. Exact solutions of Einstein's modified field equations with perfect fluid and heat conduction are obtained within the framework of Sáez-Ballester scalartensor theory of gravitation and the model is found to be in good agreement with recent observations. We find, for n = 3, k = 1, the present value of DP in derived model as q0 = −0.67 which is very near to the observed value of DP at present epoch. We find that the time-dependent DP is sensible for the present day Universe and give an earmark description of evolution of universe. Some physical and geometric properties of the models are also discussed.

Sucralose is a commonly employed artificial sweetener that behaves very differently than its natural disaccharide counterpart, sucrose, in terms of its interaction with biomolecules. The presence of sucralose in solution is found to destabilize the native structure of two model protein systems: the globular protein bovine serum albumin and an enzyme staphylococcal nuclease. The melting temperature of these proteins decreases as a linear function of sucralose concentration. We correlate this destabilization to the increased polarity of the molecule. The strongly polar nature is manifested as a large dielectric friction exerted on the excited-state rotational diffusion of tryptophan using time-resolved fluorescence anisotropy. Tryptophan exhibits rotational diffusion proportional to the measured bulk viscosity for sucrose solutions over a wide range of concentrations, consistent with a Stokes−Einstein model. For sucralose solutions, however, the diffusion is dependent on the concentration, strongly diverging from the viscosity predictions, and results in heterogeneous rotational diffusion.

This paper deals with Bianchi type VI 0 anisotropic cosmological models filled with a bulk viscous cosmic fluid in the presence of time-varying gravitational and cosmological constant. Physically realistic solutions of Einstein's field equations are obtained by assuming the conditions 1) the expansion scalar is proportional to shear scalar 2) the coefficient of the bulk viscosity is a power function of the energy density and 3) the cosmic fluid obeys the barotropic equation of state. We observe that the corresponding models retain the well established features of the standard cosmology and in addition, are in accordance with recent type Ia supernovae observations. Physical behaviours of the cosmological models are also discussed.

In this paper we consider the quantization of a scalar field coupled to gravity at one loop order. We investigate the divergences appearing in the mass (i.e. φ 2) term in the effective action. We use the Vilkovisky-DeWitt effective action technique which guarantees that the result is gauge invariant as well as gauge condition independent in contrast to traditional calculations. Our final result is to identify the complete pole part of the effective action.

By considering f (R) gravity models, the cosmic evolution is modified with respect to the standard ΛCDM scenario. In particular, the thermal history of particles results modified. In this paper, we derive the evolution of relics particles (WIMPs) assuming a reliable f (R) cosmological solution and taking into account observational constraints. The connection to the PAMELA experiment is also discussed. Results are consistent with constraints coming from BICEP2 and PLANCK experiments.

In this paper we discuss some consequences of cosmological models in which the primordial cosmic matter is described by a relativistic imperfect fluid. The latter takes into account the dissipative effects (bulk viscosity) arising from different cooling rates of the fluid components in the expanding Universe. We discuss, in particular, the effects of the bulk viscosity on Big Bang Nucleosynthesis and on the thermal relic abundance of particles, looking at recent results of PAMELA experiment. The latter has determined an anomalous excess of positron events, which cannot be explained by conventional cosmology and particle physics.

This paper deals with the study of five dimensional non-static plane symmetric cosmological model within the framework of Lyra's manifold when the source of the gravitational field is perfect fluid with pressure equal to energy density. The cosmological solutions have been analyzed through various physical and geometrical properties.

In this paper we present a bulk viscous magnetized Bianchi type IX string cosmological model in general relativity. In order to find determinate solution of the investigated model, we assume the conditions :(i) Scalar expansion is proportional to shear scalar and (ii) ξθ = constant, where ξ is bulk viscosity and θ is scalar expansion. Some physical and geometrical properties of the investigated model are also discussed.

An attempt has been taken to study the minimally interacting fields, dark matter and holographic dark energy in scalar tensor theory formulated by Saez and Ballester. The exact solution of the field equations is obtained by using the fact that the scalar expansion of the universe is proportional to the shear scalar. Some physical and geometrical aspects of the model are also discussed.

Dissipative features of dark matter affect its clustering properties and could lead to observable consequences for the evolution of large-scale structure. We analyse the evolution of cold dark matter density perturbations allowing for the possibility of bulk viscous pressure in a causal dissipative theory. Our analysis employs a Newtonian approximation for cosmological dynamics and the transport properties of bulk viscosity are described by the Israel-Stewart theory. We obtain a third order evolution equation for density perturbations. For some parameter values the density contrast can be suppressed compared to results obtained in the ΛCDM scenario. For other values causal bulk viscous dark matter can exhibit an enhancement of clustering.

We perform a global analysis of curved Friedmann-Robertson-Walker cosmologies in the presence of a viscous fluid. The fluid's bulk viscosity is governed by a first order theory recently proposed in [18], and the analysis is carried out in a compactified parameter space with dimensionless coordinates. We provide stability properties, cosmological interpretation and thermodynamic features of the critical points.

Bianchi type II massive string cosmological models with magnetic field and time dependent gauge function () in the frame work of Lyra's geometry are investigated. The magnetic field is in YZ-plane. To get the deterministic solution, we have assumed that the shear () is proportional to the expansion (). This leads to = , where R and S are metric potentials and n is a constant. We find that the models start with a big bang at initial singularity and expansion decreases due to lapse of time. The anisotropy is maintained throughout but the model isotropizes when = 1. The physical and geometrical aspects of the model in the presence and absence of magnetic field are also discussed.

Bianchi Type-I cosmological model in the presence of Saez-Ballester theory gravitation is studied. An exact solution of the field equation is given by considering the cosmological model yield a metric potential included with a real number. The relation between the deceleration parameter and Hubble parameter and average scale factor is used in that cosmological model. The effect of the viscosity on the entropy of the universe is utilized by energy momentum tensor with bulk viscous terms in a conservative manner. We obtained a formula for calculating the entropy of the universe in terms of viscosity and used it to compare to the study. Also, various physical and kinematical properties have been discussed.

Consistent interactions that can be added to a two-dimensional, free Abelian gauge theory comprising a special class of BF-type models and a collection of vector fields are constructed from the deformation of the solution to the master equation based on specific cohomological techniques. The deformation procedure modifies the Lagrangian action, the gauge transformations, as well as the accompanying algebra of the interacting model.

In this paper, we have studied on Bianchi type-III space-time with time varying Λ in presence of bulk viscosity and Chaplygin gas in the context of Lyra geometry. We solve the Einstein field equations by using the relation B = C as the expansion scalar (Θ) is proportional to the Shear scalar (σ).We find the cosmological parameters by using EoS of Chaplygin gas and the relation ΩM + ΩΛ = 1, also we observed the behavior of the gauge function β and Λ against time. Some Physical and Geometrical behaviour of the model are discussed.

Bianchi Type-I cosmological model in the presence of Saez-Ballester theory gravitation is studied. An exact solution of the field equation is given by considering the cosmological model yield a metric potential included with a real number. The relation between the deceleration parameter and Hubble parameter and average scale factor is used in that cosmological model. The effect of the viscosity on the entropy of the universe is utilized by energy momentum tensor with bulk viscous terms in a conservative manner. We obtained a formula for calculating the entropy of the universe in terms of viscosity and used it to compare to the study. Also, various physical and kinematical properties have been discussed.

An anisotropic Bianchi type-III cosmological model is investigated in the presence of a bulk viscous fluid within the framework of Lyra geometry with time-dependent displacement vector. It is shown that the field equations are solvable for any arbitrary function of a scale factor. To get the deterministic model of the universe, we have assumed that (i) a simple power-law form of a scale factor and (ii) the bulk viscosity coefficient are proportional to the energy density of the matter. The exact solutions of the Einstein’s field equations are obtained which represent an expanding, shearing, and decelerating model of the universe. Some physical and kinematical behaviors of the cosmological model are briefly discussed.

We give a new criterion of quark confinement/deconfinement by deriving a low-energy effective theory of QCD. The effective theory can explain Abelian dominance in low-energy physics of QCD, especially, quark confinement. Finally, we apply the above criterion to the large flavor QCD and discuss its phase structure. The result suggests the existence of conformal phase.

The present study deals with spatially homogeneous and totally anisotropic Bianchi type-V cosmological model in presence of bulk viscous fluid source with time dependent gravitational constant G and cosmological term  . The coefficient of bulk viscosity  is considered to be a quadratic function of Hubble parameter H (i.e. 2 2 1 0 H H        , where 0  , 1  and 2  are constants). Exact solution of Einstein’s field equations are obtained by using a particular form of Hubble’s parameter H i.e.   1 ) (   n a m a H , where 0  m , 1  n , a being a scale factor and a a H   , which provides an early deceleration and late time acceleration of the universe. From state finder diagnosis  s r, the behavior of the universe in different stages during the evolution is exhibits.

Bianchi type-V string cosmological models in general relativity are investigated. To get the exact solution of Einstein's field equations, we have taken some scale transformations used by Camci et al [Astrophys. Space Sci. 275, 391 (2001)]. It is shown that Einstein's field equations are solvable for any arbitrary cosmic scale function. Solutions for particular forms of cosmic scale functions are also obtained. Some physical and geometrical aspects of the models are discussed.

Cosmological models with time varying gravitational constant, G, and cosmological constant , in the presence of viscous fluid in Kaluza-Klein metric were investigated. The solutions to Einstein Field Equation were obtained for different types of G, with bulk coefficient ξ = ξ 0 ρ d (where ρ is density of the Universe, d is some constant) and lambda = αH 2 + βR −2 where H and R are Hubble parameter and scale factor respectively. Two possible models are suggested, one where G is proportional to H and, the other where G is inversely proportional to H. While the former leads to a non-singular model, the latter results in an inflationary model. Both Cosmological models show that the Universe is accelerating; but at the early stage of the Universe the behaviour of both models is quite different,which has been studied through the variation of decelerating parameter q with time.

We consider the homogeneous and isotropic cosmological fluid dynamics which is compatible with a homothetic, timelike motion, equivalent to an equation of state ρ + 3P = 0. By splitting the total pressure P into the sum of an equilibrium part p and a non-equilibrium part Π, we find that on thermodynamical grounds this split is necessarily given by p = ρ and Π = − 4 3 ρ, corresponding to a dissipative stiff (Zel'dovich) fluid.

Relativistic high energy heavy ion collision cross sections have been interpreted in terms of almost ideal liquid droplets of nuclear matter. The experimental low viscosity of these nuclear fluids have been of considerable recent quantum chromodynamic interest. The viscosity is here discussed in terms of the string fragmentation models wherein the temperature dependence of the nuclear fluid viscosity obeys the Vogel-Fulcher-Tammann law.

The calculation of the transport coefficients of the strong quark-gluon plasma (sQGP), i.e. sheer viscosity $\eta$, heat conductivity $\gk$ and bulk viscosity $\zeta$, in the first Chapman-Enskog approximation is presented. Their formulation in terms of two-fold integrals depending on the particle interaction, known as relativistic omega integrals, is derived and their evaluation in the ultrarelativistic limit is worked out assuming a cross section independent of the relative and total momentum of two colliding particles. We find a suppression of the bulk viscosity and a pronounced temperature dependence for the sheer viscosity and heat conductivity. However, at high temperatures, they scale with the third and second power of the temperature respectively as expected. Furthermore, we find that all results in this ultrarelativistic expansion are dominated by the leading order contribution.

FRW models of the universe have been studied in the cosmological theory based on Lyra's manifold. A new class of exact solutions has been obtained by considering a time dependent displacement field for variable deceleration parameter from which three models of the universe are derived (i) exponential (ii) polynomial and (iii) sinusoidal form respectively. The behaviour of these models of the universe are also discussed. Finally some possibilities of further problems and their investigations have been pointed out.

The semi-phenomenological improved holographic model for QCD is confronted with data of the pure glue, large-Nc gauge theory. After fitting two phenomenological parameters in the potential, the model can reproduce in detail all thermodynamic functions at finite temperature. It also reproduces in detail all known spin-0 and spin-2 glueball observables at zero temperature and predicts the rest of the 0 ++ and 2 ++ towers. A similar two parameter fit in the CP-odd sector postdicts the correct second 0 + − glueball mass, and predicts the rest of the 0 +− tower. – 1 – Contents

A new class of a spatially homogeneous and anisotropic Bianchi type-I cosmological models of the universe for perfect fluid distribution within the framework of scalar-tensor theory of gravitation proposed by Saez and Ballester (Phys. Lett. 113:467, 1986) is investigated. To prevail the deterministic solutions we choose the different scale factors which yield time-dependent deceleration parameters (DP) representing models which generate a transition of the universe from the early decelerated phase to the recent accelerating phase. Three different physically viable models of the universe are obtained in which their anisotropic solutions may enter to some isotropic inflationary era. The modified Einstein's field equations are solved exactly and the models are found to be in good concordance with recent observations. Some physical and geometric properties of the models are also discussed.

Bianchi type V bulk viscous fluid cosmological models are investigated. Using a generation technique (Camci et al., 2001), it is shown that the Einstein's field equations are solvable for any arbitrary cosmic scale function. The viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density. Solutions for particular forms of cosmic scale functions are also obtained. Some physical and geometric aspects of the models are also discussed.

We have investigated an LRS Bianchi Type I models with bulk viscosity in the cosmological theory based on Lyra’s geometry. A new class of exact solutions have been obtained by considering a time-dependent displacement field for a constant value of the deceleration parameter and viscosity coefficient of bulk viscous fluid is assumed to be a power function of mass density. The physical behaviour of the models is also discussed.

We have investigated Bianchi type-IX dust filled universe for ideal fluid distribution in creation field in which creation field is a function of time t only. To get deterministic cosmological model, we have assumed a supplementary condition a = bn, where a and b are metric potential and n is constant. Also, we have study the physical and geometrical parameters of the said cosmological model.