2,703 research outputs found

    A New Dawn : Mathematical Modelling of the Sun’s Atmosphere

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

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    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

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    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

    Three Flavor Neutrino Oscillations in Matter: Flavor Diagonal Potentials, the Adiabatic Basis and the CP phase

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    We discuss the three neutrino flavor evolution problem with general, flavor-diagonal, matter potentials and a fully parameterized mixing matrix that includes CP violation, and derive expressions for the eigenvalues, mixing angles and phases. We demonstrate that, in the limit that the mu and tau potentials are equal, the eigenvalues and matter mixing angles theta_12 and theta_13 are independent of the CP phase, although theta_23 does have CP dependence. Since we are interested in developing a framework that can be used for S matrix calculations of neutrino flavor transformation, it is useful to work in a basis that contains only off-diagonal entries in the Hamiltonian. We derive the "non-adiabaticity" parameters that appear in the Hamiltonian in this basis. We then introduce the neutrino S matrix, derive its evolution equation and the integral solution. We find that this new Hamiltonian, and therefore the S matrix, in the limit that the mu and tau neutrino potentials are the same, is independent of both theta_23 and the CP violating phase. In this limit, any CP violation in the flavor basis can only be introduced via the rotation matrices, and so effects which derive from the CP phase are then straightforward to determine. We show explicitly that the electron neutrino and electron antineutrino survival probability is independent of the CP phase in this limit. Conversely, if the CP phase is nonzero and mu and tau matter potentials are not equal, then the electron neutrino survival probability cannot be independent of the CP phase

    Review Article: MHD Wave propagation near coronal null points of magnetic fields

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    We present a comprehensive review of MHD wave behaviour in the neighbourhood of coronal null points: locations where the magnetic field, and hence the local AlfvĂ©n speed, is zero. The behaviour of all three MHD wave modes, i.e. the AlfvĂ©n wave and the fast and slow magnetoacoustic waves, has been investigated in the neighbourhood of 2D, 2.5D and (to a certain extent) 3D magnetic null points, for a variety of assumptions, configurations and geometries. In general, it is found that the fast magnetoacoustic wave behaviour is dictated by the AlfvĂ©n-speed profile. In a ÎČ=0 plasma, the fast wave is focused towards the null point by a refraction effect and all the wave energy, and thus current density, accumulates close to the null point. Thus, null points will be locations for preferential heating by fast waves. Independently, the AlfvĂ©n wave is found to propagate along magnetic fieldlines and is confined to the fieldlines it is generated on. As the wave approaches the null point, it spreads out due to the diverging fieldlines. Eventually, the AlfvĂ©n wave accumulates along the separatrices (in 2D) or along the spine or fan-plane (in 3D). Hence, AlfvĂ©n wave energy will be preferentially dissipated at these locations. It is clear that the magnetic field plays a fundamental role in the propagation and properties of MHD waves in the neighbourhood of coronal null points. This topic is a fundamental plasma process and results so far have also lead to critical insights into reconnection, mode-coupling, quasi-periodic pulsations and phase-mixing
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