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An operating systems consisting of a firm and its customers is modeled in this paper. It is imperative for managers to know whether customers are lead time sensitive or price sensitive.

Application of ratio objectives to explore profits of firms in different capacity expansions with the help of no-linear programming is analyzed.

We report the synthesis of nanocrystalline calcium carbonate with varying particle sizes by precipitation techniques from an aqueous solution of calcium nitrate and sodium carbonate at controlled pH. The particle size of the carbonate powder was precisely controlled by changing the precursor concentration. The synthesized carbonate powders were characterized by using scanning electron microscopy, X-ray diffraction technique, and transmission electron microscopy. The particle size, along with the crystallite size of as-synthesized carbonate powder, decreases with increasing precursor concentration. The non-isothermal decomposition kinetics of the carbonate powder was also evaluated by using near to the modified Arrhenius equation's exact solution. The experimental results were best fitted at n = 0.5, and the one-dimensional diffusion-controlled transport process mechanism (D 1) and one-dimensional phase boundary movement mechanism (R 1) was found to be very close fit of the corresponding evaluated g(α) value. The apparent activation energy of the nano calcium carbonate decomposition was found in the range of 120–175 kJ/mol, which is also inherently functioning with the average particle size. The apparent activation energy of decomposition of CaCO 3 found to be decreased with decreasing average particle size of nanocrystalline calcium carbonate. [ABSTRACT FROM AUTHOR]

Abstract: We propose a new model of a gravastar in () anti-de Sitter spacetime. This new three-dimensional configuration has three different regions with different equations of state: [I] Interior: , ; [II] Shell: , ; [III] Exterior: , . The outer region of this gravastar corresponds to the exterior () anti-de Sitter spacetime, popularly known as the BTZ spacetime. Like BTZ model, Λ is taken to be negative, which at the junction turns out to be positive as required by stability of gravastar and mathematical consistency. After investigating the Interior spacetime, Shell and Exterior spacetime we have highlighted different physical features in terms of Length and Energy, Entropy, and Junction conditions of the spherical distribution. It is shown that the present model of charge-free gravastar in connection to the exterior () anti-de Sitter spacetime or the BTZ spacetime is non-singular. [Copyright &y& Elsevier]

We consider a static spherically symmetric charged anisotropic fluid source of radius ∼10−16 cm by introducing a variable Λ dependent on the radial coordinate r under general relativity. From the solution sets a possible role of the cosmological constant is investigated which indicates the dependency of energy density on it. [Copyright &y& Elsevier]

In this paper, we examine the universe's expansion in f (R , L m) gravity for a particular form of f (R , L m) = R 2 + L m n. The field equations for flat FLRW metric with matter Lagrangian L m = ρ are derived. Hubble parameter in terms of red-shift(z) are derived using the linear form of Equation of State (EoS) parameter ω = w 0 + w 1 z. By using Bayesian statistical techniques based on χ 2 -minimization technique, we have obtained the best fit values of the model parameters of this model for cosmic chronometer and supernovae Pantheon datasets. The evolution of the equation of state parameter(ω), energy density (ρ), pressure (p), cosmographic parameters, and the impact of the energy conditions with best-fit values of the model parameters are all thoroughly examined. We have also analyze Om diagnostic's behaviour and determine the present age of universe for this model. • We examine the universe's expansion for a particular form of f(R,Lm). • We have obtained the best fit values of model parameters for CC and joint datasets. • Energy density, pressure, cosmographic parameters are thoroughly examined. • We have analysed Om diagnostic's behaviour and determine the age of universe. [ABSTRACT FROM AUTHOR]

The foundation of this paper is to present a comparative study of the properties of anisotropic solutions for compact stars in the framework of modified f (Q , T) gravity for the first time under the schemes of vanishing complexity, embedding class one, conformally flat and conformally Killing, where Q is the nonmetricity scalar and T is the trace of the energy-momentum tensor. The model f (Q , T) = ϕ Q + α Q n + 1 − γ (1 − e − Q / γ) + β T is chosen in order to compare the results of the various forms f (Q , T) and f (Q) gravity theories. The f (Q , T) and f (Q) gravities in this model are then further simplified to depend on parameters ϕ , α , γ & β. Then, we discussed several approaches to determining the spherically symmetric spacetime components. Schwarzschild geometry represents the exterior spacetime, while a Tolman-Kuchowiz spacetime is used to examine the spherically symmetric spacetime inside the interior geometry. Many properties of compact stars are investigated, like energy density, energy conditions, pressure profiles, sound speeds, gradients, adiabatic index, TOV equation, mass function, compactness, and redshift function are all carefully examined in order to complete the analysis. We have compiled results for both stable and unstable scenarios, derived from gravity theories categorized into various cases, with solutions considered under different frameworks such as Tolman-Kuchowiz spacetime, embedding class 1 spacetime, the vanishing complexity condition, the conformally flat condition, and the conformal Killing vector condition. [ABSTRACT FROM AUTHOR]

Abstract: This is a continuation and generalization of our earlier work on gravastar in anti-de Sitter space–time to -dimensional solution of charged gravastar. Morphologically this gravastar contains three regions, namely: (i) charged interior, (ii) charged shell and (iii) electrovacuum exterior. We have studied different characteristics in terms of Length and Energy, Entropy, and Junction conditions of the spherical charged distribution. It is shown that the present model of charged gravastar is non-singular and represents itself an alternative of black hole. [Copyright &y& Elsevier]

Abstract: We propose a new model of a gravastar admitting conformal motion. While retaining the framework of the Mazur–Mottola model, the gravastar is assumed to be internally charged, with an exterior defined by a Reissner–Nordström instead of a Schwarzschild line element. The solutions, obtained by exploiting an assumed conformal Killing vector, involve (i) the interior region, (ii) the shell, and (iii) the exterior region of the sphere. Of these three cases the first one is of primary interest since the total gravitational mass here turns out to be an electromagnetic mass under some specific conditions. This suggests that the interior de Sitter vacuum of a charged gravastar is essentially an electromagnetic mass model that must generate gravitational mass which provides a stable configuration by balancing the repulsive pressure arising from charge with its attractive gravity to avert a singularity. Therefore the present model, like the Mazur–Mottola model, results in the construction of a compact astrophysical object, as an alternative to a black hole. We have also analyzed various other aspects such as the stress energy tensor in the thin shell and the entropy of the system. [Copyright &y& Elsevier]

We explore possibility to find out a new model of gravastars in the extended D -dimensional Einstein–Maxwell space–time. The class of solutions as obtained by Mazur and Mottola of a neutral gravastar [1,2] have been observed as a competent alternative to D -dimensional versions of the Schwarzschild–Tangherlini black hole. The outer region of the charged gravastar model therefore corresponds to a higher dimensional Reissner–Nordström black hole. In connection to this junction conditions, therefore we have formulated mass and the related Equation of State of the gravastar. It has been shown that the model satisfies all the requirements of the physical features. However, overall observational survey of the results also provide probable indication of non-applicability of higher dimensional approach for construction of a gravastar with or without charge from an ordinary 4-dimensional seed as far as physical ground is concerned. [ABSTRACT FROM AUTHOR]

In the present Letter we search for a new wormhole solution inspired by noncommutative geometry with the additional condition of allowing conformal Killing vectors (CKV). A special aspect of noncommutative geometry is that it replaces point-like structures of gravitational sources with smeared objects under Gaussian distribution. However, the purpose of this letter is to obtain wormhole solutions with noncommutative geometry as a background where we consider a point-like structure of gravitational object without smearing effect. It is found through this investigation that wormhole solutions exist in this Lorentzian distribution with viable physical properties. [ABSTRACT FROM AUTHOR]

Abstract: Considering the flat rotation curves as input and treating the matter content in the galactic halo region as quark matter, we have found out a background spacetime metric for the region of the galactic halo. We obtain fairly general conditions that ensure that gravity in the halo region is attractive. We also investigate the stability of circular orbits, along with a different role for quark matter. Bag-model quark matter meeting these conditions therefore provides a suitable model for dark matter. [Copyright &y& Elsevier]

In the present paper, we propose a stellar model under the f (T) gravity following the conjecture of Mazur-Mottola [1,2] known in literature as gravastar , a viable alternative to the black hole. This gravastar has three different regions, viz., (A) Interior core region, (B) Intermediate thin shell, and (C) Exterior spherical region. It is assumed that in the interior region the fluid pressure is equal to a negative matter-energy density providing a constant repulsive force over the spherical thin shell. This shell at the intermediate region is assumed to be formed by a fluid of ultrarelativistic plasma and the pressure, which is directly proportional to the matter-energy density according to Zel'dovich's conjecture of stiff fluid [Zel'dovich (1972) [3] , does nullify the repulsive force exerted by the interior core region for a stable configuration. On the other hand, the exterior spherical region can be described by the exterior Schwarzschild-de Sitter solution. With all these specifications we have found out a set of exact and singularity-free solutions of the gravastar which presents several physically interesting as well as valid features within the framework of alternative gravity. [ABSTRACT FROM AUTHOR]

• ICT-enabled ecosystems improve fruit and vegetable consumption for farmers in Odisha. • Farm-level homegrown consumption mediates overall fruit and vegetable consumption. • Retail interventions must go beyond improving access and focus on demand generation. • Intersectoral policy-making approaches are needed to bridge value chain efforts. This paper reports results of a quasi-experimental study designed to assess the impact of an information and communication technology (ICT) –enabled ecosystem, led by the social enterprise eKutir, on household fruit and vegetable consumption in Odisha, India. eKutir aims at providing self-sustaining solutions to poverty and undernutrition in developing countries by leveraging ICTs through ecosystem development anchored into a distributed micro-entrepreneurial strategy. eKutir's farming micro-entrepreneurs (FME) provide agricultural knowledge, inputs, and market linkages at household and community level, followed by progressive integration of other micro-entrepreneurs at different points along the value chain on both supply and demand sides. The present case examined core FMEs along with retail micro-entrepreneurs (RMEs) deployed in low-resource rural and urban communities. Structural equation modeling was used to compare rural outcomes and the role of homegrown consumption as a mediator. Multivariable linear regression and ANOVA were used to test group differences in the urban sample. Positive β coefficients represent an increase in fruit and vegetable consumption in communities exposed to the eKutir ecosystem in contrast to the comparison group. Farmers in rural communities exposed to the eKutir ecosystem consumed more overall fruit and vegetables (β = 0.30, p < 0.001) and fruits alone (β = 0.53, p < 0.05) than those farmers in comparison villages unexposed to the eKutir ecosystem. This effect was concentrated in households exposed to both FMEs + RMEs (β = 0.60, p < 0.0001) and was mediated by homegrown consumption. A non-significant directional effect was observed in comparing fruit and vegetable consumption in rural households exposed to RMEs only over comparison communities. Urban consumers, exposed to the eKutir ecosystem through access to RMEs operating in their neighborhood community, did not increase their fruit or vegetable consumption compared to non-intervention communities. The results reveal the potential of reaching nutritional impacts through homegrown consumption and with farm-level support outside of governmental/philanthropic interventions through an ICT-enabled social enterprise. They also underscore, however, the challenges of both changing eating behaviour and intervening along the agri-food value chain. Implication for more effective digital ecosystem design and intersectoral policies are discussed. [ABSTRACT FROM AUTHOR]