An interfacial approximation of the streamer stage in the evolution of sparks and lightning can be written as a Laplacian growth model regularized by a ‘kinetic undercooling’ boundary condition. We study the linear stability of uniformly translating circles that solve the problem in two dimensions. In a space of smooth perturbations of the circular shape, the stability operator is found to have...

The purpose of the studies presented in this paper is to point out the need for further work towards a definitive answer to the following question: How do perturbations of a rotating black hole get radiated away? Using the Teukolsky formalism [1], we can search for an answer to that question by studying the evolution of a complex spin-weighted wavefunction that is defined in terms of curvature ...

This paper investigates the evaluation of the sensitivity, with respect to tangential perturbations of the singular point, of boundary integrals having either weak or strong singularity. Both scalar potential and elastic problems are considered. A proper definition of the derivative of a strongly singular integral with respect to singular point perturbations should accommodate the concomitant p...

We provide an in-depth investigation of quasinormal-mode oscillations of Kerr black holes with nearly extremal angular momenta. We first discuss in greater detail the two distinct types of quasinormal mode frequencies presented in a recent paper [1]. One set of modes, that we call “zerodamping modes”, has vanishing imaginary part in the extremal limit, and exists for all corotating perturbation...

Harmonic perturbations are studied for a plane parallel model for the solar magnetic atmosphere. In the present model, the magnetic field lines are horizontal, the sound speed and the Alfvén speed are constants. It is known that in this model, analytical solutions can be obtained for linearized perturbations. The harmonic perturbations can either propagate as MHD modes modified by the action of...

Tour into the picture (TIP) proposed by Horry et al.13 is a method for generating a sequence of walk-through images from a single reference picture (or image). By navigating a 3D scene model constructed from the picture, TIP produces convincing 3D effects. Assuming that the picture has one vanishing point, they proposed the scene modeling scheme called spidery mesh. However, this scheme has to ...

In the intersecting brane configurations with any number n of extra dimensions, we obtain a localized gravity on the n orthogonal non-solitonic or solitonic (n+2)-branes in the presence of higher curvature terms. In the presence of such terms there would exist a non vanishing brane tension at the four-dimensional brane intersection of the (2 + n)-branes. The effective 4d Planck scale MP l is de...

‎The object of the present paper is to study spacetimes admitting‎ ‎quasi-conformal curvature tensor‎. ‎At first we prove that a quasi-conformally flat spacetime is Einstein‎ ‎and hence it is of constant curvature and the energy momentum tensor of such a spacetime satisfying‎ ‎Einstein's field equation with cosmological constant is covariant constant‎. ‎Next‎, ‎we prove that if the perfect flui...

The paper addresses the question of the abolition of the Stability and Growth Pact. More and more authors and policymakers are arising the negative impacts of the European deficit rule on the countries and their ability to respond an asymmetric economic shock. Some others are asking for a redefinition of the Pact. If the focus is only fiscal and in light of the non-respect of the Pact by two of...