The geography fieldwork experience: Spain 2008

In the last week of April, Dr Tony Mellor and five colleagues from the School of Applied Sciences took 34 Geography students on field work to Andalucia in southern Spain. This residential trip takes place annually as part of a core module on the second year of the BSc (Hons) Geography degree programme. The module enables students to: (a) apply skills of observation, measurement and data collection in a real world field context, (b) demonstrate skills in project design, report writing, oral presentation and group work, and (c) describe and interpret physical and environmental processes operating in the study area and discuss howthey contribute to the distinctiveness of its landscapes

Tree Diagrams for String Links

In previous work, the author defined the intersection graph of a chord diagram associated with string links (as in the theory of finite type invariants). In this paper, we classify the trees which can be obtained as intersection graphs of string link diagrams.Comment: 12 pages, 14 figure

Finite Type Link Homotopy Invariants

Bar-Natan used Chinese characters to show that finite type invariants classify string links up to homotopy. In this paper, I construct the correct spaces of chord diagrams and Chinese characters for links up to homotopy. I use these spaces to show that the only rational finite type invariants of link homotopy are the pairwise linking numbers of the components.Comment: 15 pages, many figures. Revised to acknowledge work of Bar-Natan, Garoufalides, Rozansky and Thurston. Revised again to clarify the exposition in section

Structure and optics of the anterior segment of the cetacean eye : a thesis presented in fulfilment of the requirements for the degree of Master of Philosophy at Massey University

The anterior segment of the mammalian eye is concerned with the function and maintenance of its optical components, the most important of these being the maintenance of transparency and stable intraocular pressure. The structures of the eye change throughout life. Continuous growth occurs in the lens, and a number of other changes associated with aging also occur, many of which reduce visual capacity. Many of these manifest in humans because of their long life span but have very little relevance in terms of survival. However, other long lived animals such as some birds, reptiles and whales, could be severely compromised by complete or partial blindness associated with aging. The aims of this study were to evaluate the importance of vision as a sense in whales by observation of the structure and optics of the anterior segment, and compare the findings with other species whose visual functions are well known. Pathological changes were recorded where appropriate. The findings in this thesis are based on a three year survey of eyes from 45 whales in which i) differences between species in the size of the globe, lens, and cornea are described ii) the unique histological structure of the uveal tract is demonstrated and defined iii) evidence of emmetropia in both air and water from NMR images of two eyes is given iv) lens shape and capsular features which indicate that there could be a capacity for accommodation, are described, and v) lens pathology (four cataracts and one case of phacolysis) is described in five animals. The largest whales (baleen and sperm) had the largest eyes, but this was mainly due to the thickness of sclera. Internal dimensions showed little variation with respect to body size, suggesting that there is an upper limit on internal size which is dependant on the focal length of the lens, a structure which enlarges only slightly with age. Corneal and lens sizes were especially large in the baleen whales, and particularly small in the sperm whale. The uveal tract was found to be very vascular when compared to other species, and particularly well innervated with specialised nerve endings which are thought to be unique to cetaceans. Although the findings are not conclusive, evidence from this study suggests that the whales' unique uveal vasculature and aqueous drainage methods may be instrumental in modifying the dioptric strength of the eye. The abundance of specialised pressure-receptors in the ciliary body indirectly supports a proposed mechanism for this, whereby the engorged ciliary body raises intraocular pressure causing increased corneal curvature, and releases tension on the zonule to allow 'rounding up' of the lens. Optically, the study showed that eyes from two long-finned pilot whales were emmetropic by virtue of a cornea with only a very small amount of optical power in both air and water, and a very powerful lens (about 72D in water). Emmetropia was thus not affected unduly by transition from air to water as it is in most mammals, where the cornea is optically very significant in air but neutral in water. Lenses in both animals showed an unusual 'bump' on the central posterior : surface, and the increased radius of curvature in this area was responsible for the very high dioptric strength of the lenses. The prevalence of lens pathology, particularly cataracts in young animals, was high. but in all cases the cause was unknown

Finite Type Link Concordance Invariants

This paper is a generalization of the author's previous work on link homotopy to link concordance. We show that the only real-valued finite type link concordance invariants are the linking numbers of the components.Comment: 19 pages, many figures. Section 4 contained serious errors, and has been removed. To appear in The Journal of Knot Theory and its Ramification

Tree Diagrams for String Links II: Determining Chord Diagrams

In previous work, we defined the intersection graph of a chord diagram associated with a string link (as in the theory of finite type invariants). In this paper, we look at the case when this graph is a tree, and we show that in many cases these trees determine the chord diagram (modulo the usual 1-term and 4-term relations).Comment: 14 pages, many figure