Thin-shell wormholes in Einstein and Einstein-Gauss-Bonnet theories of gravity

We review recent works on the possibility for eternal existence of thin-shell wormholes on Einstein and Einstein-Gauss-Bonnet gravity. We introduce thin-shell wormholes that are categorized into a class of traversable wormhole solutions. After that, we discuss stable thin-shell wormholes with negative-tension branes in Reissner-Nordstr\"om-(anti) de Sitter spacetimes in $d$ dimensional Einstein gravity. Imposing $Z_2$ symmetry, we construct and classify traversable static thin-shell wormholes in spherical, planar and hyperbolic symmetries. It is found that the spherical wormholes are stable against spherically symmetric perturbations. It is also found that some classes of wormholes in planar and hyperbolic symmetries with a negative cosmological constant are stable against perturbations preserving symmetries. In most cases, stable wormholes are found with the appropriate combination of an electric charge and a negative cosmological constant. However, as special cases, there are stable wormholes even with a vanishing cosmological constant in spherical symmetry and with a vanishing electric charge in hyperbolic symmetry. Subsequently, the existence and dynamical stability of traversable thin-shell wormholes with electrically neutral negative-tension branes is discussed in Einstein-Gauss-Bonnet theory of gravitation. We consider radial perturbations against the shell for the solutions, which have the $Z_2$ symmetry. The effect of the Gauss-Bonnet term on the stability depends on the spacetime symmetry.Comment: 52pages, 17figures, 6tables. This article belongs to the Special Issue Recent Advances in Wormhole Physics (MDPI). This article is based on arXiv:1411.5454 [gr-qc] and arXiv:1506.08550 [gr-qc

On-line Identification of Electro-Conductivity in Electrolytic Solutions

An on-line method is proposed to identify electro-conductivity in electrolytic solutions. The method uses a model of a cell of electrolytic solutions in a micro reactor modeled by an electronic circuit. The circuit consists of a cell part with a resister and a capacitor connected in series and a measurement part having a resister. Then the resistance and the capacitance of the cell part are identified to calculate the electro-conductivity. The identification scheme is the least-square method with a forgetting factor calculated on-line. To avoid the effect of differentiation of measured signals, a filter is added to the identification method. The effectiveness of the proposed control scheme is shown by numerical simulation.</p

IRE1-XBP1 Pathway of the Unfolded Protein Response Is Required during Early Differentiation of C2C12 Myoblasts

ArticleInternational Journal of Molecular Sciences. 21(1): 182. (2019)journal articl