Effects of insect herbivores on early successional habitats

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Revolutionary Trickster Communities: Re-presenting Folk Heroes in Contemporary African American Novels

In this thesis, the three novelists, as tricksters, manipulate one’s reading process by overlapping the visible with the invisible world. This thesis explores the tricksters communities and will focus on the novelists as trickster. Sherley Anne Williams, Ernest Gaines, and Gloria Naylor parody the rebel or loner trickster tradition in literature and conceptualize a world in which African Americans, white Americans, and Native Americans work communally to deconstruct the stereotypes associated with race, age, and gender. The authors use parody as a humorous narrative technique. The humor enables the modern reader to look into the past at the wrongs imposed on African Americans by chattel slavery. Their works educate contemporary readers about the perils of slavery, racism of the 1970’s, and multicultural intolerance still present in contemporary America. Including multi-ethnic, androgynous, and various-aged members within their revolutionary trickster communities. In conclusion, these authors offer hope of growing intercommunication and tolerance among the races

Constraining sub-grid physics with high-redshift spatially-resolved metallicity distributions

Aims. We examine the role of energy feedback in shaping the distribution of metals within cosmological hydrodynamical simulations of L* disc galaxies. While negative abundance gradients today provide a boundary condition for galaxy evolution models, in support of inside-out disc growth, empirical evidence as to whether abundance gradients steepen or flatten with time remains highly contradictory. Methods. We made use of a suite of L* discs, realised with and without "enhanced" feedback. All the simulations were produced using the smoothed particle hydrodynamics code Gasoline, and their in situ gas-phase metallicity gradients traced from redshift z similar to 2 to the present-day. Present-day age-metallicity relations and metallicity distribution functions were derived for each system. Results. The "enhanced" feedback models, which have been shown to be in agreement with a broad range of empirical scaling relations, distribute energy and re-cycled ISM material over large scales and predict the existence of relatively "flat" and temporally invariant abundance gradients. Enhanced feedback schemes reduce significantly the scatter in the local stellar age-metallicity relation and, especially, the [O/Fe]-[Fe/H] relation. The local [O/Fe] distribution functions for our L* discs show clear bimodality, with peaks at [O/Fe] = -0.05 and +0.05 (for stars with [Fe/H] > -1), consistent with our earlier work on dwarf discs. Conclusions. Our results with "enhanced" feedback are inconsistent with our earlier generation of simulations realised with "conservative" feedback. We conclude that spatially-resolved metallicity distributions, particularly at high-redshift, offer a unique and under-utilised constraint on the uncertain nature of stellar feedback processes

Dryden\u27s Adaptations of Shakespeare

It is the purpose of this study to discuss Dryden\u27s adaptations of Shakespeare\u27s The Tempest, Antony and Cleopatra, and Troilus and Cressida. As a background for this study, Restoration drama will be discussed from the standpoint of the following criteria: relationship to Elizabethan drama; Restoration audiences, theaters, and fashion; adaptations, primarily of Shakespeare; D’Avenant, Dryden, and heroic drama; and finally, English opera in the Restoration period. The first of the five chapters in this discussion will be concerned with the items listed above. Succeeding chapters in order will discuss Dryden\u27s adaptations of Shakespeare’s The Tempest, Antony and Cleopatra, Troilus and Cressida, and in a summary chapter some critical conclusions will be given. In chapters two, three, and four dealing with the plays of Shakespeare which Dryden adapted, the discussion will be concerned with the theme of the plays, the structure, the plot, major and important minor characters, and imagery, and it will close with a critical summary

Properties of simulated Milky Way-mass galaxies in loose group and field environments

We test the validity of comparing simulated field disk galaxies with the empirical properties of systems situated within environments more comparable to loose groups, including the Milky Way's Local Group. Cosmological simulations of Milky Way-mass galaxies have been realised in two different environment samples: in the field and in environments with similar properties to the Local Group. Apart from the environments of the galaxies, the samples are kept as homogeneous as possible with equivalent ranges in last major merger time, halo mass and halo spin. Comparison of these two samples allow for systematic differences in the simulations to be identified. Metallicity gradients, disk scale lengths, colours, magnitudes and age-velocity dispersion relations are studied for each galaxy in the suite and the strength of the link between these and environment of the galaxies is studied. The bulge-to-disk ratio of the galaxies show that these galaxies are less spheroid dominated than many other simulated galaxies in literature with the majority of both samples being disk dominated. We find that secular evolution and mergers dominate the spread of morphologies and metallicity gradients with no visible differences between the two environment samples. In contrast with this consistency in the two samples there is tentative evidence for a systematic difference in the velocity dispersion-age relations of galaxies in the different environments. Loose group galaxies appear to have more discrete steps in their velocity dispersion-age relations. We conclude that at the current resolution of cosmological galaxy simulations field environment galaxies are sufficiently similar to those in loose groups to be acceptable proxies for comparison with the Milky Way provided that a similar assembly history is considered.Comment: 16 pages, 11 figures, abstract abridged for arXiv. Accepted for publication in Astronomy & Astrophysic

Hierarchical formation of bulgeless galaxies II: Redistribution of angular momentum via galactic fountains

Within a fully cosmological hydrodynamical simulation, we form a galaxy which rotates at 140 km/s, and is characterised by two loose spiral arms and a bar, indicative of a Hubble Type SBc/d galaxy. We show that our simulated galaxy has no classical bulge, with a pure disc profile at z=1, well after the major merging activity has ended. A long-lived bar subsequently forms, resulting in the formation of a secularly-formed "pseudo" bulge, with the final bulge-to-total light ratio B/T=0.21. We show that the majority of gas which loses angular momentum and falls to the central region of the galaxy during the merging epoch is blown back into the hot halo, with much of it returning later to form stars in the disc. We propose that this mechanism of redistribution of angular momentum via a galactic fountain, when coupled with the results from our previous study which showed why gas outflows are biased to have low angular momentum, can solve the angular momentum/bulgeless disc problem of the cold dark matter paradigm.Comment: 9 Pages, 10 Figures, accepted MNRAS version. Comments welcom