Nonlinear Alfvén wave dynamics at a 2D magnetic null point: ponderomotive force

Context: In the linear, β = 0 MHD regime, the transient properties of magnetohydrodynamic (MHD) waves in the vicinity of 2D null points are well known. The waves are decoupled and accumulate at predictable parts of the magnetic topology: fast waves accumulate at the null point; whereas Alfvén waves cannot cross the separatricies. However, in nonlinear MHD mode conversion can occur at regions of inhomogeneous Alfvén speed, suggesting that the decoupled nature of waves may not extend to the nonlinear regime. Aims: We investigate the behaviour of low-amplitude Alfvén waves about a 2D magnetic null point in nonlinear, β = 0 MHD. Methods: We numerically simulate the introduction of low-amplitude Alfvén waves into the vicinity of a magnetic null point using the nonlinear LARE2D code. Results: Unlike in the linear regime, we find that the Alfvén wave sustains cospatial daughter disturbances, manifest in the transverse and longitudinal fluid velocity, owing to the action of nonlinear magnetic pressure gradients (viz. the ponderomotive force). These disturbances are dependent on the Alfvén wave and do not interact with the medium to excite magnetoacoustic waves, although the transverse daughter becomes focused at the null point. Additionally, an independently propagating fast magnetoacoustic wave is generated during the early stages, which transports some of the initial Alfvén wave energy towards the null point. Subsequently, despite undergoing dispersion and phase-mixing due to gradients in the Alfvén-speed profile (∇c_A ≠ 0) there is no further nonlinear generation of fast waves. Conclusions: We find that Alfvén waves at 2D cold null points behave largely as in the linear regime, however they sustain transverse and longitudinal disturbances - effects absent in the linear regime - due to nonlinear magnetic pressure gradients

Conservation Easements and the Doctrine Of Merger

McLaughlin talks about conservation easements and the doctrine of merger. This article explains that merger generally should not occur in such cases because the unity of ownership that is required for the doctrine to apply typically will not be present. For merger to occur, the two estates must be in the same person at the same time and in the same right

What's in a name? the UK newspapers' fabrication and commodification of Foxy Knoxy

This chapter analyses how, immediately after the arrest of Amanda Knox, the UK’s national press played a pivotal role in transforming the American student into ‘Foxy Knoxy’, the duplicitous, psychologically disturbed femme fatale who orchestrated and participated in the sexually motivated murder of her flatmate, Meredith Kercher. This case exemplifies what happens when UK reporting restrictions do not apply, leaving journalists free to employ imaginative practices to create the infotainment spectacle that ‘Foxy Knoxy’ became and to ignore her legal right to a presumption of innocence. It is also the first example of journalists mining suspects’ social media sites and re-contextualising their text and images to provide ‘evidential’ sources of a guilty persona

The censor without, the censor within: the resistance of Johnstone’s improv to the social and political pressures of 1950s Britain

Keith Johnstone's improv, popularly known through the Theatresports format, was forged in the cultural and historical context of 1950s Britain. In this paper I will argue that Johnstone's incarnation of theatrical improvisation was defined by its reaction to the normalising forces exerted by the social elite upon the broader population and by civilised society upon the individual. Johnstone's improv was a reaction against the Lord Chamberlain’s power to censor the British stage and a challenge to the internalised 'censor' British society of the time implanted in the minds of his students, stunting their creative imaginations. Johnstone borrowed elements of professional wrestling to break down the regimented conventions of the theatre space and enliven the spectator-performer relationship. As well as echoing Roland Barthes’ idealistic analysis of professional wrestling (Barthes, 1984: n.p.), Johnstone’s improv shares Barthes’ critique of the authority of the author and allows meaning to be generated out of the encounter between performers and spectators in the instant of the performance’s emergence. Through these processes, Johnstone’s improv defies the censor without (The Lord Chamberlain) by rooting out the censor within (the socially learnt inhibitions to the creative imagination). By delineating the political and social pressures at play in the historical context of 1950s Britain and the ways that the stylistic conventions of Johnstone's improv resist and subvert these forces, I will demonstrate the emancipatory power latent in this mode of popular performance. This is a particularly timely analysis given the increasing authority of free market economics to dictate what appears on contemporary British stages, and the internalised censor that panoptical CCTV and social media is implanting within the minds of British citizens today

The spontaneity drain: the social pressures that shaped and then exiled Keith Johnstone's improvisation

Keith Johnstone’s Improvisation had an oppositional relationship to the social and historical conditions of 1950s Britain under which it developed. Its structure and performative dynamic were protests against the normalising forces exerted by the social elite upon the broader population and by civilised society upon the individual. Within this context, the Royal Court Theatre acted as an incubator that allowed Johnstone to develop his subversive theories of performance, drawing on elements of professional wrestling to break down the regimented conventions of the theatre space and enliven the spectator-performer relationship. Eventually Johnstone entered a self-imposed exile from the society that shaped this form of performance and established The Loose Moose Theatre in Calgary, Canada. This paper will analyse three relationships vital to this narrative: The oppositional reaction of Johnstone's improvisation to the social pressures of 1950's Britain, the creative glasshouse that The Royal Court Theatre provided for Johnstone within this broader cultural context, and the effects that the new social situation of Calgary, Canada had on Johnstone's practice. At the conclusion of the paper I will draw out the consequences of these analyses for contemporary British society and attempt to identify the normalising forces at work within this context, how our arts institutions and creative incubators might foster novel reactions to these pressures, and how public policy might be shaped in order to encourage artists to remain in Britain so that we might benefit from their continued contribution to our cultural discourses

Something in the Water? Testing for Groundwater Quality Information in the Housing Market

I test the level of information regarding possible groundwater contamination in the residential real estate market in Washington County, Minnesota. An approximately seven square-mile trichloroethylene plume has affected hundreds of households’ water supplies since at least 1988 in the region. I find that homeowners were initially well-informed by market forces, but were later somewhat misinformed by government actions regarding the potential of water contamination from the plume. A disclosure law passed in 2003 may have added new, low-cost, and imperfect information to the market that could explain the change in informational awareness.disclosure law, environmental disamenity, groundwater, groundwater contamination, hedonic model, incomplete information, water quality, real estate, Consumer/Household Economics, Resource /Energy Economics and Policy,