Cylindrical solutions in braneworld gravity

In this article we investigate exact cylindrically symmetric solutions to the modified Einstein field equations in the brane world gravity scenarios. It is shown that for the special choice of the equation of state $2U+P=0$ for the dark energy and dark pressure, the solutions found could be considered formally as solutions of the Einstein-Maxwell equations in 4-D general relativity.Comment: 12 pages, RevTex format, typos corrected and references added. Accepted for publication in PR

Tetrads in Geometrodynamics

A new tetrad is introduced within the framework of geometrodynamics for non-null electromagnetic fields. This tetrad diagonalizes the electromagnetic stress-energy tensor and allows for maximum simplification of the expression of the electromagnetic field. The Einstein-Maxwell equations will also be simplified

Sifat-sifat Quasi-ideal-γ Pada Semigrup-γ

Semigrup-Г S merupakan generalisasi dari semigrup. Semigrup- Г S adalah semigrup yang memuat pemetaan S×Г×S→S , yaitu (a ,γ,b) ↦aγb∈S dan memenuhi aγbμc=aγbμc untuk semua a,b,c∈S dan γ,μ∈Г . Quasi-ideal- Г Q dimana Q merupakan himpunan bagian tak kosong dari semigrup- Г S disebut quasi-ideal-Г Q jika SГQ∩QГS⊆Q . Irisan dari semua quasi-ideal-Г Q yang memuat A dengan A merupakan himpunan bagian dari semigrup- Г S , sehingga quasi-ideal- Г Q merupakan quasi-ideal-Г Q terkecil yang memuat A

Purely electromagnetic spacetimes

Electrovacuum solutions devoid of usual mass sources are classified in the case of one, two and three commuting Killing vectors. Three branches of solutions exist. Electromagnetically induced mass terms appear in some of them.Comment: 8 page

PENYELESAIAN SENGKETA DI PERBANKAN SYARIAH KHUSUSNYA PEMBIAYAAN AKAD MURABAHAH

Title disputes in Islamic banking, especially in murabaha financing agreement. The purpose of this study was to determine the development of the Islamic banking law in the world, especially in financing murabaha contract, thus standardizing contracts particularly in dispute resolution will ensure legal protection and legal certainty in every transaction made and can be used as a reference in the resolution that appears in the cult. Types of research used in this study is a normative legal research, legislation and approach of this study requires secondary data (material law) primary data, and tertiary legal materials to equip.Data used consists of primary legal materials are materials that consist of laws and regulations applicable to the problem under study. Secondary legal materials or literature consists of books, articles, working in the legal field, magazines, and materials related to the study of law. Tertiary legal materials legal materials that explain the legal materials of primary and secondary legal materials, the use of Indonesian dictionary. Results from this study is for those who aspire to conduct transactions in Islamic banking, especially in murabaha financing agreement must meet the requirements of Islamic law. In view of the scholars, the general power of attorney is not justified because it does not meet the requirements in harmony and power. This can lead wakalah contract null and void. When the lifeboat issue in accordance with the provisions of Law No. 21 of 2008 outlines the settlement of disputes in accordance with the Treaty

Noncommutative Einstein-Maxwell pp-waves

The field equations coupling a Seiberg-Witten electromagnetic field to noncommutative gravity, as described by a formal power series in the noncommutativity parameters $\theta^{\alpha\beta}$, is investigated. A large family of solutions, up to order one in $\theta^{\alpha\beta}$, describing Einstein-Maxwell null pp-waves is obtained. The order-one contributions can be viewed as providing noncommutative corrections to pp-waves. In our solutions, noncommutativity enters the spacetime metric through a conformal factor and is responsible for dilating/contracting the separation between points in the same null surface. The noncommutative corrections to the electromagnetic waves, while preserving the wave null character, include constant polarization, higher harmonic generation and inhomogeneous susceptibility. As compared to pure noncommutative gravity, the novelty is that nonzero corrections to the metric already occur at order one in $\theta^{\alpha\beta}$.Comment: 19 revtex pages. One refrence suppressed, two references added. Minor wording changes in the abstract, introduction and conclusio

Carter-like constants of the motion in Newtonian gravity and electrodynamics

For a test body orbiting an axisymmetric body in Newtonian gravitational theory with multipole moments Q_L, (and for a charge in a non-relativistic orbit about a charge distribution with the same multipole moments) we show that there exists, in addition to the energy and angular momentum component along the symmetry axis, a conserved quantity analogous to the Carter constant of Kerr spacetimes in general relativity, if the odd-L moments vanish, and the even-L moments satisfy Q_2L = m (Q_2/m)^L. Strangely, this is precisely the relation among mass moments enforced by the no-hair theorems of rotating black holes. By contrast, if Newtonian gravity is supplemented by a multipolar gravitomagnetic field, whose leading term represents frame-dragging (or if the electrostatic field is supplemented by a multipolar magnetic field), we are unable to find an analogous Carter-like constant. This further highlights the very special nature of the Kerr geometry of general relativity.Comment: 4 page