The asymmetric ABAB-matrix model describes the transfer matrix of threedimensional Lorentzian quantum gravity. We study perturbatively the scaling of the ABAB-matrix model in the neighbourhood of its symmetric solution and deduce the associated renormalization of three-dimensional Lorentzian quantum gravity. pacs: 04.60Gw, 04.20Gz, 04.60Kz, 04.60Nc Presented by J.J. at the Workshop on Random Ge...

We study the geometry of compact Lorentzian manifolds that admit a somewhere timelike Killing vector field, and whose isometry group has infinitely many connected components. Up to a finite cover, such manifolds are products (or amalgamated products) of a flat Lorentzian torus and a compact Riemannian (resp., lightlike) manifold.

A conventional Stokes description of polarized light is considered in a four-dimensional Lorentzian space, developing a seminal idea of Paul Soleillet [Ann. Phys. (Paris) 12, 23 (1929)]. This provides a striking interpretation for the degree of polarization and the Stokes decomposition of light beams. Malus law and reciprocity theorems for polarizers are studied using this Lorentzian formalism.

The aim of this paper is to determine Frenet-Serret invariants of non-null curves in Lorentzian 5-space. First, we define a vector product of four vectors, by this way, we present a method to calculate Frenet-Serret invariants of the non-null curves. Additionally, an algebraic example of presented method is illustrated. Keywords—Lorentzian 5-space; Frenet-Serret Invariants; Nonnull Curves.

We study the geometric structure of Lorentzian spin manifolds, which admit imaginary Killing spinors. The discussion is based on the cone construction and a normal form classification of skew-adjoint operators in signature (2, n−2). Derived geometries include Brinkmann spaces, Lorentzian Einstein-Sasaki spaces and certain warped product structures. Exceptional cases with decomposable holonomy o...

The object of the present paper is to study three-dimensional Lorentzian -Sasakian manifolds which are Ricci-semisymmetry, locally symmetric and have -parallel Ricci tensor. An example of a three-dimensional Lorentzian -Sasakian manifold is given which verifies all the Theorems.

In this note a proof is given for local existence and uniqueness of minimal surfaces with the topology of the halfplane respectively a cylinder of Lorentzian type with values in certain Lorentzian manifolds for given initial values up to the first derivatives. Global existence is proved for the case that the target manifold is diffeomorphic to Rn.

We present a reduced magnetohydrodynamic (MHD) mathematical model describing the dynamical behavior of highly conducting plasmas with frozen-in magnetic fields, constrained by assumption that, there exists frame reference, where field vector, $\mathbf{B}$, is aligned plasma velocity $\mathbf{u}$, at each point. call this solution "stream-aligned MHD" (SA-MHD). Within framework model, electric f...

aligned and random nanocomposite nanofibrous scaffolds were electrospun from polycaprolactone (pcl), poly (vinyl alcohol) (pva) and hydroxyapatite nanoparticles (nha). the morphology and mechanical characteristics of the nanofibers were evaluated using scanning electron microscopy and tensile testing, respectively. scanning electron microscopy revealed fibers with an average diameter of 123 ± 3...