Newtonian nonlinear hydrodynamics and magnetohydrodynamics

We use covariant methods to analyse the nonlinear evolution of self-gravitating, non-relativistic media. The formalism is first applied to imperfect fluids, aiming at the kinematic effects of viscosity, before extended to inhomogeneous magnetised environments. The nonlinear electrodynamic formulae are derived and successively applied to electrically resistive and to highly conductive fluids. By nature, the covariant equations isolate the magnetic effects on the kinematics and the dynamics of the medium, combining mathematical transparency and physical clarity. Employing the Newtonian analogue of the relativistic 1+3 covariant treatment, also facilitates the direct comparison with the earlier relativistic studies and helps to identify the differences in an unambiguous way. The purpose of this work is to set the framework and take a first step towards the detailed analytical study of complex nonlinear systems, like non-relativistic astrophysical plasmas and collapsing protogalactic clouds.Comment: Typos corrected, references added and updated (MNRAS in press

Primordial magnetic seed field amplification by gravitational waves: comment on gr-qc/0503006

We consider the amplification of cosmological magnetic fields by gravitational waves as it was recently presented in [gr-qc/0503006]. That study confined to infinitely conductive environments, arguing that on spatially flat Friedmann backgrounds the gravito-magnetic interaction proceeds always as if the universe were a perfect conductor. We explain why this claim is not correct and then re-examine the Maxwell-Weyl coupling at the limit of ideal magnetohydrodynamics. We find that the scales of the main results of [gr-qc/0503006] were not properly assessed and that the incorrect scale assessment has compromised both the physical and the numerical results of the paper. This comment aims to clarify these issues on the one hand, while on the other it takes a closer look at the gauge-invariance and the nonlinearity of [gr-qc/0503006].Comment: Revised version, to appear in PR

Emerging Scathed: A Critical Analysis of Current Approaches to Domestic Violence – Fusing Punitive & Restorative Solutions

As the UK is taking steps to emerge from Covid-19 pandemic related restrictions, the tail-end of the pandemic itself seemingly in sight, as people, a Nation, residents of this world, we are faced with certain grim realities. One such reality, is the knowledge that during the extended lockdown period there was a substantial increase in ‘police recorded domestic abuse crimes’ (Ivandic, Kirchmaeir and Linton, 2021). Specifically, Refuge and Respect, charities against domestic violence, submitted, in a BBC report, an astounding 60-70% increase in reports of domestic violence to their call centres from female and male victims respectively, during the initial period of lockdown, describing it as an ‘epidemic beneath a pandemic’ (June, 2021). In a quick turn of events, present Government responded quickly. Not only was additional funding provided to preventative and reporting services, but new legislation was passed, the Domestic Abuse Act 2021, helping to illustrate and cement the seriousness of domestic violence. Yet, despite their efforts, both the legislation passed, and the funding provided should not, in fact, serve as the end-goal for the cause. Rather, as cornerstones of a movement, they should pave the way for additional survivor-centred approaches to take root. The newly enacted legislation purports to be supportive of a legal approach predominantly punitive in nature, focusing on the offender, rather than restorative thus aiming to rectify the harm afflicted upon the victims of domestic abuse. The article at hand will attempt to illustrate how overemphasis on a punitive approach might not necessarily be in the public’s best interest. Acknowledging the legislation’s marginal attempts at a dual approach, a further attempt will be made to critically analyse current measures and how while they may be a significant step in the right direction, better provisions could have been enacted in certain circumstances. On a final note, an effort will be made to demonstrate how specific restorative practices can be highly beneficial in dealing with certain instances of domestic violence, when utilised in tandem with the current punitive approach