Massless particles in S-Matrix theory

Imperial Users onl

Prediction of PWR fuel cladding failure strain in a loss-of-coolant accident

Imperial Users onl

Microwave cavity light shining through a wall optimization and experiment

It has been proposed that microwave cavities can be used in a photon regeneration experiment to search for hidden sector photons. Using two isolated cavities, the presence of hidden sector photons could be inferred from a 'light shining through a wall' phenomenon. The sensitivity of the experiment has strong a dependence on the geometric construction and electromagnetic mode properties of the two cavities. In this paper we perform an in depth investigation to determine the optimal setup for such an experiment. We also describe the results of our first microwave cavity experiment to search for hidden sector photons. The experiment consisted of two cylindrical copper cavities stacked axially inside a single vacuum chamber. At a hidden sector photon mass of 37.78 micro eV we place an upper limit on the kinetic mixing parameter chi = 2.9 * 10^(-5). Whilst this result lies within already established limits our experiment validates the microwave cavity `light shining through a wall' concept. We also show that the experiment has great scope for improvement, potentially able to reduce the current upper limit on the mixing parameter chi by several orders of magnitude.Comment: To be published in PR

'Makings of the self and of the sun': Modernist Poetics of Climate Change

This thesis aims to formulate a critical methodology and a poetics that engage with climate change. It critiques the Romantic and social justice premises of literary ecocriticism, arguing that a modernist poetics more capably articulates the complexities exacerbated in anthropogenic climate change. Analysing the form of a range of modernist work, I assess its expression of the human–climate relations at the root of the planet's present state, and trace this work's influence on contemporary climate change poetry. Ecocriticism's topical approaches to nature and the environment have been constitutively unable to grapple with climate change until the discipline's recent synthesis of literary theory, and the emergence of a 'material ecocriticism' informed by developments in environmental sociology, ethics and philosophy. Modernist aesthetics has an array of concerns in common with this critical thinking on climate change, and the reciprocity of the two prompts my rereading here of key modernist texts. T. S. Eliot's 'The Waste Land' is seen to reveal civilisation's inability to suppress or surpass its environment; Wallace Stevens's opus exposes the necessarily fictive quality of our relations with nature; Basil Bunting extends Stevens's reconsideration of Romanticism with the diminishment of selfhood and breakdown of order in his poetry; while David Jones's 'The Anathemata' employs the scope of modernist poetics to understand the prehistoric climate change that enabled the emergence of civilisation. By being conscious of modernist traditions, new work – as exemplified here by Jorie Graham's 'Sea Change' – acknowledges the role of human culture in creating the world imaginatively and phenomenally. As contemporary climate change poetry moves away from using culturally familiar elegiac modes, it benefits from a fuller range of resources to articulate the entanglement and hybridity of nature and culture in the twenty-first century

A note on the discovery of stone tools on Erith Island, the Kent Group, Bass Strait

Between Erith and Dover there is what is known among the local fisherman as 'The Swashway', a low spit of pebbles linking the two islands at low tide but covered by broken surf at other times. Overlooking this swashway is a saddle some 40-50m above sea level mantled with deep sand deposits, part of which is now being scoured away by the wind. It was here that the first flake had been found, and we quickly confirmed this find by discovering about a score more flakes and tools mostly heavily wind eroded on the floor of this saddle

A theoretical and computational study of heterogeneous spatio-temporal distributions arising from density-dependent animal movement with applications to slugs in arable fields

Understanding the dynamics of pest populations is essential for pest management in agriculture. Slugs alone can cause large amounts of economic damage if their population is not controlled, usually by the application of chemical pesticides. However, there is pressure to reduce the amount of pesticide used because of the potential effects on human health and the environment. One solution to this problem is to target the application of pesticide only on areas of high population density. This thesis thoroughly investigates the mechanisms in individual movement that can lead to the formation of heterogeneous spatial distributions in a population. Using an individual based model, we show that when an animal's direction of movement is dependent on the population density in its immediate surroundings, the population can form several clusters of high density. We show that the characteristics of the clusters and their temporal stability are dependent on how individual animals move, with Brownian motion producing dense stable clusters and Lévy flight producing dynamic clusters that are highly volatile. We confirm the existence of density dependent movement behaviour through an analysis of spatial tracking data from a field experiment where slugs were released in either a group or individually. Differences in individual movement seen in the data are shown to produce a heterogeneous population distribution through another individual based model. Finally, we analyse data of slug trap counts and discuss methods that can be used for identifying high density patches that should be targeted by pesticide

Facile synthesis of 7-alkyl-1,2,3,4-tetrahydro-1,8-naphthyridines as arginine mimetics using a Horner-Wadsworth-Emmons-based approach

Integrin inhibitors based on the tripeptide sequence Arg-Gly-Asp (RGD) are potential therapeutics for the treatment of idiopathic pulmonary fibrosis (IPF). Herein, we describe an expeditious three-step synthetic sequence of Horner-Wadsworth-Emmons olefination, diimide reduction, and global deprotection to synthesise cores for these compounds in high yields (63-83% over 3 steps) with no need for chromatography. Key to this transformation is the phosphoramidate protecting group, which is stable to metalation steps