Mass formulae for spherically symmetric stellar configurations in five dimensional space-time

An expression is derived where the mass is connected to an integral over the pressure of gravitating matter in the frame work of five dimensional(5D) space-time.Comment: 5 pages Latex, No figur

Kozmološki model sa strunama i stranom kvarkovskom tvari u Kantowski-Sachsovom prostoru-vremenu

We study the string cloud cosmological model in the context of Kantowski-Sachs space-time. For this purpose, the Einstein\u27s field equations are solved for Kantowski-Sachs space-time with strange quark matter coupled to the string cloud by using the relation between metric potentials. The physical and kinematical parameters of the models are studied.Proučavamo kozmološki model s oblakom struna u Kantowski-Sachsovom prostoruvremenu. S tim su ciljem riješene Einsteinove jednadžbe polja za Kantowski-Sachsov prostor-vrijeme, sa stranom kvarkovskom tvari vezanom s oblakom struna, primjenom relacija među metričkim potencijalima. Razmatraju se fizički i kinematički parametri modela

Kozmološki model sa strunama i stranom kvarkovskom tvari u Kantowski-Sachsovom prostoru-vremenu

We study the string cloud cosmological model in the context of Kantowski-Sachs space-time. For this purpose, the Einstein\u27s field equations are solved for Kantowski-Sachs space-time with strange quark matter coupled to the string cloud by using the relation between metric potentials. The physical and kinematical parameters of the models are studied.Proučavamo kozmološki model s oblakom struna u Kantowski-Sachsovom prostoruvremenu. S tim su ciljem riješene Einsteinove jednadžbe polja za Kantowski-Sachsov prostor-vrijeme, sa stranom kvarkovskom tvari vezanom s oblakom struna, primjenom relacija među metričkim potencijalima. Razmatraju se fizički i kinematički parametri modela

Implications of Social Media and Socio-Economic Activities on Micro and Small Enterprises in India

Purpose: The purpose of this research is to examine the implications of social media and socio-economic activities on micro and small enterprises in India.   Theoretical framework: The study will be based on the theories of social capital, network effects, and digital divide.   Design/methodology/approach: The research will be conducted using a mixed-methods approach, including both qualitative and quantitative data collection methods. Surveys and interviews will be conducted with micro and small enterprise owners in India to gather data on their use of social media and their socio-economic activities.   Findings: The findings of the study will explore the ways in which social media and socio-economic activities impact the growth and success of micro and small enterprises in India. This includes the potential for increased connectivity and networking opportunities, as well as the potential for digital divide and limited access to resources.   Research, practical and social implications: The research will have implications for policymakers and small business owners in India, as it will provide insight into the potential benefits and challenges of using social media for small business growth and success. It will also contribute to the broader literature on the impact of digital technologies on small businesses in developing countries.   Originality/value: This study fills a gap in the literature by focusing on the specific context of micro and small enterprises in India, and by using a mixed-methods approach to explore the implications of social media and socio-economic activities on these businesses

Bianchijev kozmološki model tipa I u Lyrinoj mnogostrukosti

Bianchi type-I cosmological model in Lyra\u27s manifold is obtained assuming a massless scalar field as the source of gravitational field. Some physical and geometrical properties of the model are discussed.Razvili smo Bianchijev kozmološki model tipa I u Lyrinoj mnogostrukosti kada je izvor gravitacijskog polja bezmaseno skalarno polje. Raspravljaju se neka fizička i geometrijska svojstva modela

Bianchijev kozmološki model tipa I u Lyrinoj mnogostrukosti

Bianchi type-I cosmological model in Lyra\u27s manifold is obtained assuming a massless scalar field as the source of gravitational field. Some physical and geometrical properties of the model are discussed.Razvili smo Bianchijev kozmološki model tipa I u Lyrinoj mnogostrukosti kada je izvor gravitacijskog polja bezmaseno skalarno polje. Raspravljaju se neka fizička i geometrijska svojstva modela

LRS Bianchi Type V Universe in Creation-Field Cosmology

Abstract. The Hoyle-Narlikar C-field cosmology with LRS Bianchi type-V space-time has been studied. Using methods of Narlikar and Padmanabham [1], the solutions have been obtained when the creation field C is a function of time t only. The geometrical and physical aspects of the model are also examined

Multi-fluid cosmology: An illustration of fundamental principles

Our current understanding of the Universe depends on the interplay of several distinct "matter" components, which interact mainly through gravity, and electromagnetic radiation. The nature of the different components, and possible interactions, tends to be based on the notion of coupled perfect fluids (or scalar fields). This approach is somewhat naive, especially if one wants to be able to consider issues involving heat flow, dissipative mechanisms, or Bose-Einstein condensation of dark matter. We argue that a more natural starting point would be the multi-purpose variational relativistic multi-fluid system that has so far mainly been applied to neutron star astrophysics. As an illustration of the fundamental principles involved, we develop the formalism for determining the non-linear cosmological solutions to the Einstein equations for a general relativistic two-fluid model for a coupled system of matter (non-zero rest mass) and "radiation" (zero rest mass). The two fluids are allowed to interpenetrate and exhibit a relative flow with respect to each other, implying, in general, an anisotropic Universe. We use initial conditions such that the massless fluid flux dominates early on so that the situation is effectively that of a single fluid and one has the usual Friedmann-Lemaitre-Robertson-Walker (FLRW) spacetime. We find that there is a Bianchi I transition epoch out of which the matter flux dominates. The situation is then effectively that of a single fluid and the spacetime evolves towards the FLRW form. Such a transition opens up the possibility of imprinting observable consequences at the specific scale corresponding to the transition time.Comment: 12 pages, 6 figures, version taking account of referee remark

Variable Modified Chaplygin Gas in Anisotropic Universe with Kaluza-Klein Metric

In this work, we have consider Kaluza-Klein Cosmology for anisotropic universe where the universe is filled with variable modified chaplygin gas (VMCG). Here we find normal scalar field $\phi$ and the self interacting potential $V(\phi)$ to describe the VMCG Cosmology. Also we graphically analyzed the geometrical parameters named {\it statefinder parameters} in anisotropic Kaluza-Klein model. Next, we consider a Kaluza-Klein model of interacting VMCG with dark matter in the Einstein gravity framework. Here we construct the three dimensional autonomous dynamical system of equations for this interacting model with the assumption that the dark energy and the dark matter are interact between them and for that we also choose the interaction term. We convert that interaction terms to its dimensionless form and perform stability analysis and solve them numerically. We obtain a stable scaling solution of the equations in Kaluza-Klein model and graphically represent solutions.Comment: 11 pages, 13 figure

Reconstruction of f(R)f(R), f(T)f(T) and f(G)f(\mathcal{G}) models inspired by variable deceleration parameter

We study an special law for the deceleration parameter, recently proposed by Akarsu and Dereli, in the context of $f(R)$, $f(T)$ and $f(\mathcal{G})$ theories of modified gravity. This law covers the law of Berman for obtaining exact cosmological models to account for the current acceleration of the universe, and also gives the opportunity to generalize many of the dark energy models having better consistency with the cosmological observations. Our aim is to reconstruct the $f(R)$, $f(T)$ and $f(\mathcal{G})$ models inspired by this law of variable deceleration parameter. Such models may then exhibit better consistency with the cosmological observations.Comment: 18 pages, Published online in Astrophys. Space. Sc