Image registration under conformal diffeomorphisms : a thesis presented in partial fulfilment of the requirements for the degree of Doctor of Philosophy in Mathematics at Massey University, Palmerston North, New Zealand

Image registration is the process of finding an alignment between two or more images so that their appearance matches. It has been widely studied and applied to several fields, including medical imaging and biology (where it is related to morphometrics). In biology, one motivation for image registration comes from the work of Sir D'Arcy Thompson. In his book On Growth and Form he presented several examples where a grid superimposed onto a two-dimensional image of one species was smoothly deformed to suggest a transformation to an image of another species. His examples include relationships between species of fish and comparison of human skulls with higher apes. One of Thompson's points was that these deformations should be as `simple' as possible. In several of his examples, he uses what he calls an isogonal transformation, which would now be called conformal, i.e., angle-preserving. His claims of conformally-related change between species were investigated further by Petukhov, who used Thompson's grid method as well as computing the cross-ratio (which is an invariant of the Möbius group, a finite-dimensional subgroup of the group of conformal diffeomorphisms) to check whether sets of points in the images could be related by a Möbius transformation. His results suggest that there are examples of growth and evolution where a Möbius transformation cannot be ruled out. In this thesis, we investigate whether or not this is true by using image registration, rather than a point-based invariant: we develop algorithms to construct conformal transformations between images, and use them to register images by minimising the sum-of-squares distance between the pixel intensities. In this way we can see how close to conformal the image relationships are. We develop and present two algorithms for constructing the conformal transformation, one based on constrained optimisation of a set of control points, and one based on gradient flow. For the first method we consider a set of different penalty terms that aim to enforce conformality, based either on discretisations of the Cauchy-Riemann equations, or geometric principles, while in the second the conformal transformation is represented as a discrete Taylor series. The algorithms are tested on a variety of datasets, including synthetic data (i.e., the target is generated from the source using a known conformal transformation; the easiest possible case), and real images, including some that are not actually conformally related. The two methods are compared on a set of images that include Thompson's fish example, and a small dataset demonstrating the growth of a human skull. The conformal growth model does appear to be validated for the skulls, but interestingly, not for Thompson's fish

Laser-induced breakdown spectroscopy experimentation and applications

This is an era of rapid production and fast growth. Reliable and fast analytical testing techniques are an essential part of manufacturing industries and testing and certifying authorities. Laser-Induced Breakdown Spectroscopy (LIBS) is one of the highly potential techniques to compete in this competitive arena for rapid elemental analysis which can be further used for real-time composition monitoring in the production line, post-production inspection, scrap sorting and even for classification of biological samples. In addition, remote and stand-off modes of operation increase the application potential of LIBS by many folds. It can be deployed in physically inaccessible or potentially unsafe areas. Compact LIBS systems have made its portability possible which implies ease of in-situ deployment

Rotherham, rochdale, and the racialised threat of the 'Muslim Grooming Gang'

For over a decade, British Muslims have been at the forefront of political, media and societal concerns in regards to terrorism, radicalisation, women’s rights, segregation and, most recently, the sexual exploitation and abuse of young women. Demonised, marginalised and criminalised due to inflammatory political rhetoric, inaccurate, irresponsible and sensationalist media reporting, discriminatory counter terrorism policies and legislation and state surveillance, British Muslims have emerged as a perceived racialised threat. This has continued apace with the onset of the Rochdale and Rotherham ‘grooming’ child sexual abuse scandals which in popular discourse have been dominated by representations focusing on race, ethnicity and the dangerous masculinities of Muslim men. This disproportionate and racist narrative served to both frame and limit the debate relating to the sexual exploitation and violence experienced by young female victims at a pivotal moment when the issue had been brought to national attention. This article compares and contrasts the representations and discourse of racialised and non-racialised reporting of child sexual abuse and situates the ‘grooming’ scandals in the context of anti-Muslim racism. It argues that the development of the British Muslim as a racialised threat is a current and on-going legacy of colonialism in which this group experiences discriminatory ‘othering’ processes resulting in their marginalisation

Association of drusen deposition with choroidal intercapillary pillars in the aging human eye

PURPOSE. To determine the pattern of drusen accumulation with age and to investigate the initial sites of deposition and their relationship to choroidal capillaries in human donor eyes from the eye bank of Moorfields Eye Hospital.METHODS. Wholemounted, hydrated preparations of the choriocapillaris and Bruch's membrane from donor eyes ranging from 42 to 95 years, with or without retinal pigment epithelium (RPE), were examined by conventional and confocal microscopy. Drusen were visualized by their autofluorescence.RESULTS. In all age groups studied autofluorescent drusen were present at the equator but were not found centrally where the vascular architecture is different, being tubular rather than a honeycomb pattern. Autofluorescing drusen were strongly associated with the lateral walls of the choriocapillaris (an area commonly known as the intercapillary pillars of the choriocapillaris (P = 0.028; Wilcoxon signed ranks test). Nonfluorescing drusen were occasionally seen centrally, but were not easily identified, and because of their large size, their localization with respect to capillary walls was not possible.CONCLUSIONS. These results strongly support the notion that autofluorescent drusen are not randomly distributed and have a specific spatial relationship to choroidal vessel walls. That equatorial drusen fluoresce, whereas central drusen do not, suggests that they may have different chemical compositions at the two sites and possibly different significance in age-related macular disease

Immunisation programmes in Sindh and Balochistan desperately need a shot in the arm

Pakistan has a high infant mortality rate, which is linked to low levels of immunisation. There is an urgent need for coordination among institutes for reducing demand and supply gaps in enhancing immunisation coverage nationally write Ghamz E Ali Siyal and Shahbaz Tufail

Un ordonnanceur assurant des services différenciés relatifs basés sur le délai

peer reviewedNous proposons l'ordonnanceur RD-VC garantissant des services différenciés (DiffServ) relativement quantifiés basés sur le délai. Un tel ordonnanceur assure que différentes classes de service obtiennent des délais inversement proportionnels à des indices de qualité fixés, quelle que soit la charge du réseau, et sans signalisation, ni contrôle d'admission. De plus, bien que cet algorithme ne s'applique qu'aux classes de services, les délais relatifs sont également respectés pour chaque flux composant ces agrégats. Ceci permet d'assurer des qualités de service au niveau des (micro)flux sans que leur grand nombre ne conduise à un effondrement du système. L'algorithme offre de bonnes performances tout en étant très peu coûteux : le traitement par paquet est très léger et il n'est même pas nécessaire de disposer d'une file d'attente par classe de service

Health State Utility Values for Age-Related Macular Degeneration: Review and Advice

Health state utility values are a major source of uncertainty in economic evaluations of interventions for age-related macular degeneration (AMD). This review identifies and critiques published utility values and methods for eliciting de novo utility values in AMD. We describe how utility values have been used in healthcare decision making and provide guidance on the choice of utility values for future economic evaluations for AMD. Literature was searched using PubMed, and health technology assessments (HTA) were searched using HTA agency websites to identify articles reporting utility values or approaches to derive utility values in AMD and articles applying utilities for use in healthcare decision making relating to treatments for AMD. A total of 70 studies qualified for data extraction, 22 of which were classified as containing utility values and/or elicitation methods, and 48 were classified as using utility values in decision making. A large number of studies have elicited utility values for AMD, although those applied to decision making have focused on a few of these. There is an appreciation of the challenges in the measurement and valuation of health states, with recent studies addressing challenges such as the insensitivity of generic health-related quality of life (HRQoL) questionnaires and utility in the worse-seeing eye. We would encourage careful consideration when choosing utility values in decision making and an explicit critique of their applicability to the decision problem