The mineralogy and mode of occurrence of the platinoid and associated minerals in the Merensky horizon of the Western Bushveld

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The Discrete radon transform: A more efficient approach to image reconstruction

The Radon transform and its inversion are the mathematical keys that enable tomography. Radon transforms are defined for continuous objects with continuous projections at all angles in [0,π). In practice, however, we pre-filter discrete projections take

The course of disability in the very old :drivers and trajectories

PhD ThesisIn recent decades the rapid growth in the numbers of the very old, those aged 85 years and above, has made them the fastest growing age group of most populations worldwide. Nevertheless we know little about their health and disability, the latter being a particularly important aspect of quality of life for individuals but also more widely as a major determinant for residential care. This thesis uses a unique study, the Newcastle 85+ Study, a longitudinal, population based cohort study of people born in 1921 and aged 85 years at first interview in 2006, to explore the disablement process in very late life through three substantive sub-studies. In the first sub-study I explore how disability unfolds through the order of loss in basic and instrumental activities of daily living [(I)ADLs, these being the building blocks of disability. (I)ADLs were lost in a specific order, activities requiring long distance mobility and balance (for example shopping) being lost first and those requiring upper body strength (e.g. dressing, feeding) last and with little difference between men and women. The second sub-study examines the impact of specific diseases on disability onset and finds that arthritis, diabetes and cognitive impairment were similarly disabling for men and women, cardiac disease was more disabling in women, and cardiovascular disease and respiratory disease disabling for women only. The final sub-study uses novel statistical techniques to uncover patterns of disability from age 85 to 90. Four distinct trajectories of disability were found for both sexes, with a disability-free trajectory being identified in men but not women, and all other trajectories showing increasing levels of disability. These sub-studies are discussed in the light of other literature, the extent to which they explain the greater disability yet survival of women (the disability-survival paradox), and the implications for the future

Hegel\u27s Unconscious: Analyzing Matter in the Philosophy of Nature

This thesis analyzes the structural position of matter within the philosophical system of nineteenth century German philosopher Georg Wilhelm Friedrich Hegel. Concentrating on the Philosophy of Nature, it reads Hegel’s treatment of matter psychoanalytically and semiotically as the unconscious to his anthropological (spiritual) and logical philosophy, which otherwise constitutes the majority of his writings. To do so, this thesis explores a proliferation of figurative language throughout Hegel’s text, specifically in his writing on mechanics, light, the elements, and organic life. In this investigation, Hegel’s work is considered alongside the work of Julia Kristeva, Georges Bataille, Gaston Bachelard, and Rodolphe Gasché, among others, in order to more fully explore how matter might act as a conceptual repository for what is repressed in the construction of philosophical systems. Implicitly, this thesis also attempts to provide a critique of the ideological appropriation of the philosophical category of reality

Lossless Image Compression via Predictive Coding of Discrete Radon Projections

International audienceThis paper investigates predictive coding methods to compress images represented in the Radon domain as a set of projections. Both the correlation within and between discrete Radon projections at similar angles can be exploited to achieve lossless compression. The discrete Radon projections investigated here are those used to define the Mojette transform first presented by Guedon et al. [Psychovisual image coding via an exact discrete Radon transform, in: T.W. Lance (Ed.), Proceedings of the Visual Communications AND Image Processing (VCIP), May 1995, Taipei, Taiwan, pp. 562-572]. This work is further to the preliminary investigation presented by Autrusseau et al. [Lossless compression based on a discrete and exact radon transform: a preliminary study, in: Proceedings of the IEEE International Conference on Acoustics, Speech, and Signal Processing (ICASSP), vol. II, May 2006, Toulouse, France, pp. 425-428]. The 1D Mojette projections are re-arranged as two dimensional images, thus allowing the use of 2D image compression techniques onto the projections. Besides the compression capabilities, the Mojette transforms brings an interesting property: a tunable redundancy. As the Mojette transform is able to both compress and add redundancy, the proposed method can be viewed as a joint lossless source-channel coding technique for images. We present here the evolution of the compression ratio depending on the chosen redundancy

HIGH-RESOLUTION STABLE ISOTOPE ANALYSIS OF BIOGENIC CARBONATES AS PROXY EVIDENCE FOR HOLOCENE ENVIRONMENTAL CHANGE: EXAMPLES FROM AUTHIGENIC LAKE CARBONATE AND BIVALVE ISOTOPE PROFILES

Biogenic carbonates are valuable archives of paleoenvironmental information because they record chemical signatures of ambient environmental conditions during their formation. Therefore, long-term records of biogenic carbonates provide long-term records of environmental conditions that can be utilized to develop climate histories for specific regions to explore past climatic change. Traditionally, these studies have been conducted with low temporal resolution owing to analytical or economical restrictions. Although these records provide valuable information surrounding long-term climatic change, they lack the resolution to resolve the short-term climatic oscillations such as the Pacific Decadal Oscillation and El Niño Southern Oscillation that drive environmental change. This dissertation focuses on using high-resolution stable isotope analysis of biogenic carbonates for paleoenvironmental reconstruction and associated applications. Three studies are presented herein, applying increasing sampling resolution from sub-centennial, to sub-decadal, to sub-seasonal, that illustrate the diversity of paleoenvironmental information gained with each increase in resolution. The first study uses sub-centennial oxygen isotope analysis of authigenic lake carbonate to assess how climate change has affected precipitation patterns in the southern Yukon Territory from the end of the last glacial to the present day. Large changes in atmospheric circulation patterns associated with changes in the strength of the North Pacific High and the Aleutian Low pressure systems lead to variations in the oxygen isotope value of precipitation in the southwest Yukon Territory recorded in the oxygen isotope values of lake carbonate. The degradation of a glacial anticyclone led to a reduction in strength of the Aleutian Low coupled with an increase in the strength of the North Pacific High resulting in an increase in summer precipitation to the southwest Yukon represented by an increase in effective moisture following the transition from the Late Pleistocene to the Early Holocene. The second study is a sub-decadal oxygen isotope record of lacustrine carbonate stretching back 8,000 years to quantify the strength and state of the Pacific/North American (PNA) Index through time. This study relies on the relationship between the PNA Index and the oxygen isotope values of precipitation from central Canada (Birks and Edwards, 2009), and the ability of Sturgeon Lake to accurately represent 18O values of precipitation. Results show that the strength of the PNA varied through time. The Early to Mid-Holocene (8,000- 4,200 years BP) is characterized by large fluctuations between PNA+ and PNA– phases; PNA–-like conditions dominate the period after 4,200 years BP; and ~1,800 years BP PNA+-like conditions resume. Changes in the Holocene PNA pattern are shown to be contemporaneous with similar changes in Holocene records of El Niño illustrating the intrinsic relationship between Pacific climate patterns. The final study uses sub-seasonal oxygen isotope records from bivalves derived from an overwash deposit to define the seasonality of the deposit. Data indicate a late spring to early summer timing of deposition that presents an alternative interpretation to the previous late fall tsunami origin hypothesis. In conclusion, this dissertation focused on improving our understanding of how paleoenvironmental information is archived in biogenic carbonates by focusing on the use of high-resolution sampling strategies. Modifying the sampling resolution resulted in an enhanced understanding of how short-term climate oscillations drive climate and illustrates how the type of paleoenvironmental information generated varies with sampling resolution

Fast Mojette Transform for Discrete Tomography

A new algorithm for reconstructing a two dimensional object from a set of one dimensional projected views is presented that is both computationally exact and experimentally practical. The algorithm has a computational complexity of O(n log2 n) with n = N^2 for an NxN image, is robust in the presence of noise and produces no artefacts in the reconstruction process, as is the case with conventional tomographic methods. The reconstruction process is approximation free because the object is assumed to be discrete and utilizes fully discrete Radon transforms. Noise in the projection data can be suppressed further by introducing redundancy in the reconstruction. The number of projections required for exact reconstruction and the response to noise can be controlled without comprising the digital nature of the algorithm. The digital projections are those of the Mojette Transform, a form of discrete linogram. A simple analytical mapping is developed that compacts these projections exactly into symmetric periodic slices within the Discrete Fourier Transform. A new digital angle set is constructed that allows the periodic slices to completely fill all of the objects Discrete Fourier space. Techniques are proposed to acquire these digital projections experimentally to enable fast and robust two dimensional reconstructions.Comment: 22 pages, 13 figures, Submitted to Elsevier Signal Processin

Redundant Image Representation via Multi-Scale Digital Radon Projection

International audienceA novel ordering of digital Radon projections co-efficients is presented here that enables progressive image reconstruc- tion from low resolution to full resolution. The digital Radon transform applied here is the Mojette transform first defined by Guedon et al. in [1]. The Mojette transform is a natural way to generate redundancy to any specified degree and has been demonstrated to be useful for redundant representation for robust data storage and transmission. Combining this with the wavelet transform facilitates compression, i.e., joint source-channel coding, along with the additional property of scalability

Lossless Image Compression and Selective Encryption Using a Discrete Radon Transform

International audienceIn this paper we propose a new joint encryption and loss- less compression technique designed for large images 1 . The proposed technique takes advantage of the Mojette transform properties, and can easily be included in a distributed storage architecture. The basic crypto-compression scheme presented is based on a cascade of Radon projection which enables fast encryption of a large amount of digital data. Standard encryp- tion techniques, such as AES, DES, 3DES, or IDEA can be applied to encrypt very small percentages of high resolution images. As the proposed scheme uses standard encryption, and only transmits uncorrelated data along with the encrypted part, this technique takes benefit of the security related to the chosen encryption standard, here, we assess its performances in terms of processing time and compression ratio

Projections of dependency and associated social care expenditure for the older population in England to 2038: effect of varying disability progression

Objectives: to assess the effect of recent stalling of life expectancy and various scenarios for disability progression on projections of social care expenditure between 2018 and 2038, and the likelihood of reaching the Ageing Society Grand Challenge mission of five extra healthy, independent years at birth. Design: two linked projections models: the Population Ageing and Care Simulation (PACSim) model and the Care Policy and Evaluation Centre long-term care projections model, updated to include 2018-based population projections. Population: PACSim: about 303,589 individuals aged 35 years and over (a 1% random sample of the England population in 2014) created from three nationally representative longitudinal ageing studies. Main outcome measures: Total social care expenditure (public and private) for older people, and men and women's independent life expectancy at age 65 (IndLE65) under five scenarios of changing disability progression and recovery with and without lower life expectancy. Results: between 2018 and 2038, total care expenditure was projected to increase by 94.1%-1.25% of GDP; men's IndLE65 increasing by 14.7% (range 11.3-16.5%), exceeding the 8% equivalent of the increase in five healthy, independent years at birth, although women's IndLE65 increased by only 4.7% (range 3.2-5.8%). A 10% reduction in disability progression and increase in recovery resulted in the lowest increase in total care expenditure and increases in both men's and women's IndLE65 exceeding 8%. Conclusions: interventions that slow down disability progression, and improve recovery, could significantly reduce social care expenditure and meet government targets for increases in healthy, independent years