On the Definition of Averagely Trapped Surfaces

Previously suggested definitions of averagely trapped surfaces are not well-defined properties of 2-surfaces, and can include surfaces in flat space-time. A natural definition of averagely trapped surfaces is that the product of the null expansions be positive on average. A surface is averagely trapped in the latter sense if and only if its area $A$ and Hawking mass $M$ satisfy the isoperimetric inequality $16\pi M^2 > A$, with similar inequalities existing for other definitions of quasi-local energy.Comment: 4 page

Enduring perceptions: Placenaming and the perception of Louisiana’s salt dome islands

© 2016 – Institute of Island Studies, University of Prince Edward Island, Canada. Salt domes are geological features that occur when areas of salt deposits are pressured into layers above them, causing dome shaped distortions in horizontal strata. In some instances, the distortions protrude above flat areas of land or else appear underwater as seamounts. In the case of the five Louisiana salt dome hills considered in this article, their distinct elevation above the swampy bayous and flatlands surrounding them has led to their characterisation as islands by indigenous Atakapa-Ishak peoples and by subsequent Francophone and Anglophone settlers. The article considers the ways in which the five salt domes’ islandness has been perceived, enhanced and/or undermined by various local inhabitants and/or the industries that have operated on them. Discussion of these aspects involves consideration of the manner in which the salt dome islands’ islandness is mutable and complex, particularly with regard to human impacts. This mutability is discussed with regard to both individual island placenames and the islands’ overall designations

Gaming e tide: E territorialisation of temporarily exposed English sandbanks for social cricket events

© 2017 Institution for Marine and Island Cultures, Mokpo National University. Over the last 200 years a number of sandbanks that rise above the surface of the sea or river estuaries for brief periods during low tide points have been site of cricket matches organised by teams based in adjacent coastal areas. The most regular locations for such performances have been the Goodwin Sands (an area of sandbanks located in the English Channel, close to the coast of the English county of Kent) and the Bramble Bank in the Solent. Other locations, such as banks in the River Tamar, have also seen one-off events of this kind. The article identifies these sports occasions as constituting particular forms of temporary territorialisations of space that adapt aspects of the game for the conditions of rapidly changing locations. The annual matches provide an example of the human rendition of spaces as temporary island neighbourhoods, the ephemerality of which is key to their attraction and meaning. Notably, they also involve a return to conventions of traditionally recognised ‘fair play’ in cricket that have significantly diminished in the modern form of the game. In this manner, the temporary spaces of the sandbanks allow for a revival of customs that relate to earlier participatory performance traditions and allow these to be re-affirmed

Oecusse and the Sultanate of Ocussi-Ambeno: Pranksterism, misrepresentation and micro-nationality

Occussi-Ambeno, a fictional sultanate initially conceived by Aotearoan/ Zealander anarchist artist Bruce Grenville in 1968 and represented and developed by him and others over the last fifty years, is notable as both an early example of a virtual micronation (i.e. a type that does not attempt to enact itself within the physical territory it claims) and as an entity affixed to an entire pre-existent territory (in the case of the Sultanate of Occussi- Ambeno, that of Oecusse on the north-west coast of the island of Timor). The latter aspect is pertinent in that however imaginary the micronation is, its association with a region of a small state raises questions concerning the ethics of (mis)representation. This is particularly pertinent in the case of Oecusse, which was occupied by Indonesian forces in 1975 and had its distinct identity subsumed within the Indonesian state until Timor-Leste (and Oecusse as its exclave) successfully gained independence in 2002. Discussions in the article compare the anarcho- pranksterist impulse behind the creation of the Sultanate of Occussi-Ambeno and its manifestation in visual media – primarily through the design and production of ‘artistamps’ (faux postage stamps) – to related economic and socio-political contexts

Secessionism, submergence and Siteresponsive art: The Embassy of the Commonwealth of New Bayswater at the 1st Fremantle Biennale

© 2018, Shima Publications (Australia). Assertions of territorial and, particularly, micronational secession have often been highly performative and/or rhetorical. In this regard, they closely parallel aspects of conceptual, performance and installation art practice. It is unsurprising then that a number of prominent micronations have been formed by artists in response to local issues and/or as components of broader artistic projects. The Embassy of the Commonwealth of New Bayswater, created by Perth artist Jessee Lee Johns for the inaugural Fremantle Biennale in 2017, is a prime example of site-responsive art's ability to provide illuminating representations of key issues in local discourse. The installation merits sustained consideration in this journal due to its intersection with recent debates concerning micronationality in the form of its wry engagement with aspects of Western Australian secessionist politics. Its other significant aspect is its address to issues of sea level rise, encroachment and submergence - a phenomenon whose impacts are likely to over-ride the viability of many low-lying territories let alone any secessionist pretensions individuals or communities inhabiting them may have

Gravitational radiation from dynamical black holes

An effective energy tensor for gravitational radiation is identified for uniformly expanding flows of the Hawking mass-energy. It appears in an energy conservation law expressing the change in mass due to the energy densities of matter and gravitational radiation, with respect to a Killing-like vector encoding a preferred flow of time outside a black hole. In a spin-coefficient formulation, the components of the effective energy tensor can be understood as the energy densities of ingoing and outgoing, transverse and longitudinal gravitational radiation. By anchoring the flow to the trapping horizon of a black hole in a given sequence of spatial hypersurfaces, there is a locally unique flow and a measure of gravitational radiation in the strong-field regime.Comment: 5 revtex4 pages. Additional comment

Salt marsh synthesis: Local politics, local identity perception and autonomy initiatives on canvey island (Essex, UK)

© 2018 — Institute of Island Studies, University of Prince Edward Island, Canada. Canvey Island, located on the north side of the Thames Estuary, has experienced periodic inundations since its earliest periods of settlement. The island was sparsely populated until the late 1800s when a series of developments, including the construction of fixed links to the mainland, attracted migrants from the East End of London who went on to form the core of the present-day population. The recent and relatively homogenous nature of this migration pattern has led to a local perception of difference from the more established communities of the adjacent Essex shore. The latter factor has contributed to a growing push for local autonomy on the island, which has connected with broader national political trends. The article identifies the manner in which experiences and perceptions of insularity can foster distinct senses of local difference and marginalisation that result in autonomy initiatives at grassroots levels. With regard to the latter, parallels are also drawn with previous local autonomy initiatives in the United Kingdom, particularly those of the Isle of Dogs in 1970. The article also emphasises the role of the imagination and representation of locality in promotional, popular cultural and political discourse that informs senses of community identity in various ways