Static Einstein-Maxwell Solutions in 2+1 dimensions

We obtain the Einstein-Maxwell equations for (2+1)-dimensional static space-time, which are invariant under the transformation $q_0=i\,q_2,q_2=i\,q_0,\alpha \rightleftharpoons \gamma$. It is shown that the magnetic solution obtained with the help of the procedure used in Ref.~\cite{Cataldo}, can be obtained from the static BTZ solution using an appropriate transformation. Superpositions of a perfect fluid and an electric or a magnetic field are separately studied and their corresponding solutions found.Comment: 8 pages, LaTeX, no figures, to appear in Physical Review

Synthesis And Characterization Of Polyynes End-Capped By Biphenyl Groups ({\Alpha},{\Omega}-Biphenylpolyynes)

Stable polyyne chains terminated with biphenyl end groups (a,u-biphenylpolyynes) were synthesized in a single step through a simple procedure by using the Cadiot-Chodkiewicz reaction conditions. The a,ubiphenylpolyynes were separated through HPLC analysis and identified by means of their electronic absorption spectra. The a,u-biphenylpolyynes were studied by FT-IR and Raman spectroscopy and the spectral interpretation was supported with DFT calculations. A peculiarly low reactivity of a,u-biphenylpolyynes with ozone was observed.Comment: The research leading to these results has received funding from the European Research Council Consolidator Grant EspLORE (ERC-2016-CoG Grant No.724610

All Static Circularly Symmetric Perfect Fluid Solutions of 2+1 Gravity

Via a straightforward integration of the Einstein equations with cosmological constant, all static circularly symmetric perfect fluid 2+1 solutions are derived. The structural functions of the metric depend on the energy density, which remains in general arbitrary. Spacetimes for fluids fulfilling linear and polytropic state equations are explicitly derived; they describe, among others, stiff matter, monatomic and diatomic ideal gases, nonrelativistic degenerate fermions, incoherent and pure radiation. As a by--product, we demonstrate the uniqueness of the constant energy density perfect fluid within the studied class of metrics. A full similarity of the perfect fluid solutions with constant energy density of the 2+1 and 3+1 gravities is established.Comment: revtex4, 8 page

Can a Kasner Universe with a Viscous Cosmological Fluid be Anisotropic?

A Bianchi type -I metric of Kasner form is considered, when the space is filled with a viscous fluid. Whereas an ideal (nonviscous) fluid permits the Kasner metric to be anisotropic provided that the fluid satisfies the Zel'dovich equation of state, the viscous fluid does not permit the Kasner metric to be anisotropic at all. In the latter case, we calculate the Kasner (isotropic) metric expressed by the fluid's density, pressure, and bulk viscosity, at some chosen instant $t=t_0$. The equation of state is also calculated. The present paper is related to a recent Comment of Cataldo and del Campo [Phys. Rev. D, scheduled to April 15, 2000], on a previous work of the present authors [Phys. Rev. D {\bf 56}, 3322 (1997)].Comment: 8 pages, LaTeX, no figures. To appear in PR

The role of spelling in learning to read.

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139815/1/LangandEdnPaper.pd

Regular charged black hole construction in 2+1 -dimensions

It is well-known that unlike its chargeless version the charged Banados-Teitelboim-Zanelli (BTZ) black hole solution in 2+1- dimensional spacetime is singular. We construct a charged, regular extension of the BTZ black hole solution by employing nonlinear Born-Infeld electrodynamics, supplemented with the Hoffmann term and gluing different spacetimes. The role of the latter term is to divide spacetime in a natural way into two regions by a circle and eliminate the inner singularity. Thermodynamics of such a black hole is investigated by Kaluza-Klein reduction to the 1+1-dimensional dilaton gravity.Comment: 9 pages, 2 figures, final version for publication in Physics Letters