Purely magnetic locally rotationally symmetric spacetimes

We consider all purely magnetic, locally rotationally symmetric (LRS) spacetimes. It is shown that such spacetimes belong to either LRS class I or III by the Ellis classification. For each class the most general solution is found exhibiting a disposable function and three parameters. A Segré classification of purely magnetic LRS spacetimes is given together with the compatibility requirements of two general energy–momentum tensors. Finally, implicit solutions are obtained, in each class, when the energy–momentum tensor is a perfect fluid.

Home range, habitat selection and diet of foxes (vulpes vulpes) in a semi-urban riparian environment

Between 2000 and 2002 the home range, habitat selection and diet of foxes were examined in the Dandenong Creek Valley, Melbourne, Australia. The mean home range was 44.6 ha (range 19.2–152.6 ha). A significant selection towards blackberry and gorse used as diurnal shelter was found during the day with an active avoidance of less structurally complex vegetation types. Although there was obvious selection of certain habitats, the diet of the foxes was highly general and opportunistic and thus offers little potential as a factor to manipulate in order to reduce fox abundance. Given the strong preference for blackberry and gorse as a shelter resource, a habitat-manipulation strategy is suggested whereby patches of blackberry and gorse are removed and replaced with less structurally complex vegetation. Such a strategy has the potential to influence the density of foxes in semi-urban riparian environments such as those discussed in this study.

Scope for further analytical solutions for constant flux infiltration into a semi-infinite soil profile or redistribution in a finite soil profile.

We attempt to generate new solutions for the moisture content form of the one-dimensional Richards' [1931] equation using the Lisle [1992] equivalence mapping. This mapping is used as no more general set of transformations exists for mapping the one-dimensional Richards' equation into itself. Starting from a given solution, the mapping has the potential to generate an infinite number of new solutions for a series of nonlinear diffusivity and hydraulic conductivity functions. We first seek new analytical solutions satisfying Richards' equation subject to a constant flux surface boundary condition for a semi-infinite dry soil, starting with the Burgers model. The first iteration produces an existing solution, while subsequent iterations are shown to endlessly reproduce this same solution. Next, we briefly consider the problem of redistribution in a finite-length soil. In this case, Lisle's equivalence mapping is generalized to account for arbitrary initial conditions. As was the case for infiltration, however, it is found that new analytical solutions are not generated using the equivalence mapping, although existing solutions are recovered.

High technology nanocomposite fibres: Development of melt spun semi-aromatic polyamide nanocomposite fibres

Novel polyamide nanocomposite fibres have been produced by compounding semi aromatic Poly (m-xylene adipamide) (MXD6) and organophilic Montmorillonite (MMT). Partially orientated fibres (POF) of MXD6 nanocomposite were obtained by melt spinning on a multifilament fibre extrusion system at three different speeds. The effect of the drawing velocity
on the mechanical properties of the filaments has been determined. Tensile measurements indicated that the introduction of the nanoparticies by melt intercalation improves the tenacity and toughness of the resulting polyamide fibres. The microstructure of the nanocomposites was examined by X-ray diffraction and Transmission Electron Microscope (TEM) and shown to
be an exfoliated disordered structure. The thermal stability of MXD6 nanocomposites was analysed by thermo gravimetric analysis (TGA) suggesting stabilisation of the clay and the polymer systems above 450°C.

Food utilisation and digestive ability of aquatic and semi-terrestrial crayfishes, Cherax destructor and Engaeus sericatus (Astacidae, Parastacidae)

Both Engaeus sericatus and Cherax destructor are omnivorous crayfishes consuming a variety of food items. Materials identified in the faeces of both E. sericatus and C. destructor consisted of mainly plant material with minor amounts of arthropod animals, algae and fungi. The morphology of the gastric mill of C. destructor suggests that it is mainly involved in crushing of food material while the gastric mill of E. sericatus appears to be better suited to cutting of food material. Given this, the gastric mill of E. sericatus may be better able to cut the cellulose and hemicellulose fibres associated with fibrous plant material. In contrast, the gastric mill of C. destructor appears to be more efficient in grinding soft materials such as animal protein and algae. Both species accumulated high amounts of lipids in their midgut glands (about 60% of the dry mass) which were dominated by triacylglycerols (81–82% of total lipids). The dominating fatty acids were 16:0, 16:1(n-7), 18:1(n-9), 18:2(n-6), and 18:3(n-3). The two latter fatty acids can only be synthesised by plants, and are thus indicative of the consumption of terrestrial plants by the crayfishes. The similarity analysis of the fatty acid patterns showed three distinct clusters of plants and each of the crayfish species. The complement of digestive enzymes, proteinases, total cellulase, endo-β-1,4-glucanase, β-glucosidase, laminarinase and xylanase within midgut gland suggests that both C. destructor and E. sericatus are capable of hydrolysing a variety of substrates associated with an omnivorous diet. Higher activities of total cellulase, endo-β-1,4-glucanase and β-glucosidase indicate that E. sericatus is better able to hydrolyse cellulose within plant material than C. destructor. In contrast to E. sericatus, higher total protease and N-acetyl-β-d-glucosaminidase activity in the midgut gland of C. destructor suggests that this species is better able to digest animal materials in the form of arthropods. Differences in total cellulase and gastric mill morphology suggest that E. sericatus is more efficient at digesting plant material than C. destructor. However, the contents of faecal pellets and the fatty acid compositions seem to indicate that both species opportunistically feed on the most abundant and easily accessible food items.

Semi-hyperbolic mappings in Banach spaces

The definition of semi-hyperbolic dynamical systems generated by Lipschitz continuous and not necessarily invertible mappings in Banach spaces is presented in this thesis. Like hyperbolic mappings, they involve a splitting into stable and unstable spaces, but a slight leakage from the strict invariance of the spaces is possible and the unstable subspaces are assumed to be finite dimensional. Bi-shadowing is a combination of the concepts of shadowing and inverse shadowing and is usually used to compare pseudo-trajectories calculated by a computer with the true trajectories. In this thesis, the concept of bi-shadowing in a Banach space is defined and proved for semi-hyperbolic dynamical systems generated by Lipschitz mappings. As an application to the concept of bishadowing, linear delay differential equations are shown to be bi-shadowing with respect to pseudo-trajectories generated by nonlinear small perturbations of the linear delay equation. This shows robustness of solutions of the linear delay equation with respect to small nonlinear perturbations. Complicated dynamical behaviour is often a consequence of the expansivity of a dynamical system. Semi-hyperbolic dynamical systems generated by Lipschitz mappings on a Banach space are shown to be exponentially expansive, and explicit rates of expansion are determined. The result is applied to a nonsmooth noninvertible system generated by delay differential equation. It is shown that semi-hyperbolic mappings are locally φ-contracting, where -0 is the Hausdorff measure of noncompactness, and that a linear operator is semi-hyperbolic if and only if it is φ-contracting and has no spectral values on the unit circle. The definition of φ-bi-shadowing is given and it is shown that semi-hyperbolic mappings in Banach spaces are φ-bi-shadowing with respect to locally condensing continuous comparison mappings. The result is applied to linear delay differential equations of neutral type with nonsmooth perturbations. Finally, it is shown that a small delay perturbation of an ordinary differential equation with a homoclinic trajectory is ‘chaotic’.

Financial liberalisation in Vietnam : impact on loans from informal, formal and semi-formal providers

This paper commences with an overview of the Vietnamese financial sector and a survey of the main reforms to this sector implemented since the late 1980s. A descriptive analysis is then provided, which compares some key characteristics of pre- and post-financial reform borrowing and savings activities using the Vietnam Living Standard Surveys of 1992/93 and 1997/98.

SEMI-SYNTHETIC MATERIAL

The invention relates to a modified ultra-fine natural fibre powder for use in a melt forming process for the preparation of a semi-synthetic material, the powder including particles of a natural fibre modified to improve the heat stability of the natural fibre powder particles during said melt forming process. The invention also relates to a semi-synthetic material including a modified ultra-fine natural fibre powder and a synthetic polymer component.

Semi-synthetic material

The invention relates to a modified ultra-fine natural fibre powder for use in a melt forming process for the preparation of a semi-synthetic material, the powder including particles of a natural fibre modified to improve the heat stability of the natural fibre powder particles during said melt forming process. The invention also relates to a semi-synthetic material including a modified ultra-fine natural fibre powder and a synthetic polymer component.