Swirling astrophysical flows - efficient amplifiers of Alfven waves

We show that a helical shear flow of a magnetized plasma may serve as an efficient amplifier of Alfven waves. We find that even when the flow is purely ejectional (i.e., when no rotation is present) Alfven waves are amplified through the transient, shear-induced, algebraic amplification process. Series of transient amplifications, taking place sequentially along the flow, may result in a cascade amplification of these waves. However, when a flow is swirling or helical (i.e., some rotation is imposed on the plasma motion), Alfven waves become subject to new, much more powerful shear instabilities. In this case, depending on the type of differential rotation, both usual and parametric instabilities may appear. We claim that these phenomena may lead to the generation of large amplitude Alfven waves and the mechanism may account for the appearance of such waves in the solar atmosphere, in accretion-ejecion flows and in accretion columns. These processes may also serve as an important initial (linear and nonmodal) phase in the ultimate subcritical transition to MHD Alfvenic turbulence in various kinds of astrophysical shear flows.Comment: 12 pages, 11 figures, accepted for publication (25-11-02) in Astronomy and Astrophysic

On linear coupling of acoustic and cyclotron waves in plasma flows

It is found that in magnetized electrostatic plasma flows the velocity shear couples ion-acoustic waves with ion-cyclotron waves and leads, under favorable conditions, to their efficient reciprocal transformations. It is shown that in a two-dimensional setup this coupling has a remarkable feature: it is governed by equations that are exactly similar to the ones describing coupling of sound waves with internal gravity waves [Rogava & Mahajan: Phys. Rev. E vol.55, 1185 (1997)] in neutral fluid flows. Using another noteworthy quantum mechanical analogy we calculate transformation coefficients and give fully analytic, quantitative description of the coupling efficiency for flows with low shearing rates.Comment: 5 pages, no figures. Submitted to "Physics of Plasmas

The Role of The Georgian Orthodox Church in Resistance to LGBTQ Equality: Examining Discourses and Geopolitical Implications

This thesis examines the discourses employed by the Georgian Orthodox Church's (GOC) regarding LGBTQ rights. It explores the geopolitical position of the GOC through the discourses utilised and inspects intersections with the discourses of the far-right groups in relation to LGBTQ equality. Through qualitative research using critical discourse analysis, the study uncovers the dynamics of the GOC’s rhetoric. By referring to the theories about nationalism, sexuality and geopolitics and their intersection comprehensive analysis of the GOC’s discourses is achieved. The research showed that the GOC uses the discourse of religious nationalism by establishing a strong link between being Georgian and being an Orthodox Christian and portrays LGBTQ equality as a threat to Georgian traditions. It also utilises concepts discussed in relation to human rights which allows the GOC to present its discourses in the broader framework of cultural relativism and implies that it does not discriminate against LGBTQ people, but rather defends traditional values and interests of the majority. Far-right groups have adopted the same discourse as the Church and reject the idea of LGBTQ as something forced from the West. In this regard, the Georgian far-right is no different from worldwide populist tactic to defend traditional values from the West. As the research indicated, regarding LGBTQ rights the GOC has employed the similar discourse as Russia. Far-right groups employ the same religious nationalistic discourse and they oppose EU integration referring to it as a threat to Georgian identity

Amplification of MHD waves in swirling astrophysical flows

Recently it was found that helical magnetized flows efficiently amplify Alfv\'en waves (Rogava et al. 2003, A&A, v.399, p.421). This robust and manifold nonmodal effect was found to involve regimes of transient algebraic growth (for purely ejectional flows), and exponential instabilities of both usual and parametric nature. However the study was made in the incompressible limit and an important question remained open - whether this amplification is inherent to swirling MHD flows per se and what is the degree of its dependence on the incompressibility condition. In this paper, in order to clear up this important question, we consider full compressible spectrum of MHD modes: Alfv\'en waves (AW), slow magnetosonic waves (SMW) and fast magnetosonic waves (FMW). We find that helical flows inseparably blend these waves with each other and make them unstable, creating the efficient energy transfer from the mean flow to the waves. The possible role of these instabilities for the onset of the MHD turbulence, self-heating of the flow and the overall dynamics of astrophysical flows are discussed.Comment: 8 pages, 9 figures, accepted for publication (18.03.2003) in the "Astronomy and Astrophysics