The purpose of this paper is to explore how accretion discs manifest the phenomenon of transient growth on a global scale. We investigate analytically the time response of a thin accretion disc to particular axisymmetric perturbations. To facilitate an analytical treatment we replace the energy equation with a general polytropic assumption. The asymptotic expansion of Kluźniak & Kita (2000), wh...

The purpose of this paper is to explore the steady state and dynamical behavior of thin, axisymmetric, viscous accretion disks. To facilitate an analytical treatment we replace the energy equation with a general polytropic assumption. The asymptotic expansion of Kluźniak & Kita (2000, Three-dimensional structure of an alpha accretion disk [arXiv:astro-ph/0006266]), which extended the method of ...

Polytropic murine leukemia viruses (MLVs) are generated by recombination of ecotropic MLVs with members of a family of endogenous proviruses in mice. Previous studies have indicated that polytropic MLV isolates comprise two mutually exclusive antigenic subclasses, each of which is reactive with one of two monoclonal antibodies termed MAb 516 and Hy 7. A major determinant of the epitopes disting...

Following an approach initially outlined by McKee & Holliman [5], we investigate the structure and stability of dense, starless molecular cloud cores. We model those as spherical clouds in hydrostatic equilibrium and supported against gravity by thermal, turbulent, and magnetic pressure. We determine the gas pressure by solving for thermal equilibrium between heating and cooling, while the turb...

This paper develops understanding and appropriate techniques for characterising mist generation from super-saturated liquid-air systems. Whilst the technology for this technique originates from Wilson (1897), to date mainly a qualitative understanding of the relationship between mist characteristics and initial control conditions exists. Here, an improved design of cloud chamber, which facilita...

Spherically symmetric hydrodynamical outflows accelerated thermally in the vicinity of a compact object are studied by generalizing an equation of state with a variable effective polytropic index, appropriate to describe relativistic temperatures close to the central object and nonrelativistic ones further away. Relativistic effects introduced by the Schwarzschild metric and the presence of rel...

The Rayleigh-Taylor instability plays an important role in the dynamics of several astronomical objects, in particular, in supernovae (SN) evolution. In this paper we develop an analytical approach to study the stability analysis of spherical expansion of the SN ejecta by using a special transformation in the co-moving coordinate frame. We first study a non-stationary spherical expansion of a g...

We investigate the structure of self-gravitating polytropic stellar systems. We present a method which allows to obtain approximate analytical solutions, ψn+ǫ(x), of the nonlinear Poisson equation with the polytropic index n+ ǫ, given the solution ψn(x) with the polytropic index n, for any positive or negative ǫ such that |ǫ| ≪ 1. Application of this method to the spherically symmetric stellar ...

Classical self-similar solutions to the interaction of two arbitrary planar rarefaction waves for the polytropic Euler equations in two space dimensions are constructed. The binary interaction represents a major type of interaction in the two-dimensional Riemann problems, and includes in particular the classical problem of the expansion of a wedge of gas into vacuum. Based on the hodograph tran...

Mammalian genomes harbor a large number of retroviral elements acquired as germ line insertions during evolution. Although many of the endogenous retroviruses are defective, several contain one or more intact viral genes that are expressed under certain physiological or pathological conditions. This is true of the endogenous polytropic retroviruses that generate recombinant polytropic murine le...