Dynamic contrast-enhanced CT in the investigation of tumour angiogenesis and haemodynamics

This manuscript presents an investigation and application of the medical radiographic technique of Dynamic Contrast-enhanced Computed Tomography with an emphasis on its application to the measurement of tissue perfusion using the techniques of CT Perfusion. CT Perfusion was used in association with Fluoro- Deoxy Glucose Positron Emission Tomography (FDG PET) to investigate altered blood flow due to the angiogenic effects of tumour in the clinical setting of medical imaging for cancer diagnosis and staging. CT perfusion, CT enhancement and Doppler ultrasound studies were compared in a series of patient studies performed for the assessment of metastatic liver disease. There was good correlation between all techniques for the arterial phase but not between Doppler measurements of the portal phase and any CT measurement. A new method was developed for quantifying CT perfusion and enhancement values, the Standardised Perfusion Value (SPV) and the Standardised Enhancement Value (SEV). The SPV was shown to correlate with FDG uptake in a series of 16 patient studies of lung nodules, an unexpected and potentially important finding that if confirmed in a larger study may provide an additional diagnostic role for CT in the assessment of lung nodules. Investigation of a commercially available package for the determination of CT Perfusion, CT Perfusion GE Medical Systems, was undertaken in a small series of brain studies for assessment of acute stroke. This data set showed the technique to positively identify patients with non-hemorrhagic stroke in the presence of a normal conventional CT, to select those cases where thrombolysis is appropriate, and to provide an indication for prognosis. An investigation of the accuracy and cost-effectiveness of FDG PET in solitary pulmonary nodules using Australian data was carried out. FDG PET was found to be accurate, cost saving and cost effective for the characterisation of indeterminate solitary pulmonary nodules in Australia. This work was expanded to include the impact of quantitative contrast enhancement CT (QECT) on the cost-effectiveness of FDG PET. The addition of QECT is a cost effective approach, however whether QECT is used alone or in combination with FDG PET will depend on local availability of PET, the cost of PET with respect to surgery and the prior probability of malignancy. A published review of CT perfusion, clinical applications and techniques, is included in the body of the work. Dynamic contrast-enhanced CT and FDG PET were used to investigate blood flow, expressed as SPV, and metabolic relationships in non-small cell lung cancers (NSCLC) of varying size and stage. A significant correlation between SPV and FDG uptake was only found for tumours smaller than 4.5 cm2. Blood flow-metabolic relationships are not consistent in NSCLC but depend on tumour size and stage. Dynamic contrast-enhanced CT as an adjunct to an FDG study undertaken using integrated PET-CT offers an efficient way to augment the assessment of tumour biology with possible future application as part of clinical care. In summary the work has developed a method for standardizing the results of dynamic contrast-enhanced CT and investigated its potential when applied with FDG PET to improve the diagnosis and staging of cancers

Classification of unarmed/armed personnel using the NetRAD multistatic radar for micro-Doppler and singular value decomposition features

In this letter, we present the use of experimental human micro-Doppler signature data gathered by a multistatic radar system to discriminate between unarmed and potentially armed personnel walking along different trajectories. Different ways of extracting suitable features from the spectrograms of the micro-Doppler signatures are discussed, particularly empirical features such as Doppler bandwidth, periodicity, and others, and features extracted from singular value decomposition (SVD) vectors. High classification accuracy of armed versus unarmed personnel (between 90% and 97% depending on the walking trajectory of the people) can be achieved with a single SVD-based feature, in comparison with using four empirical features. The impact on classification performance of different aspect angles and the benefit of combining multistatic information is also evaluated in this letter

Estimating the Number of Stable Configurations for the Generalized Thomson Problem

Given a natural number N, one may ask what configuration of N points on the two-sphere minimizes the discrete generalized Coulomb energy. If one applies a gradient-based numerical optimization to this problem, one encounters many configurations that are stable but not globally minimal. This led the authors of this manuscript to the question, how many stable configurations are there? In this manuscript we report methods for identifying and counting observed stable configurations, and estimating the actual number of stable configurations. These estimates indicate that for N approaching two hundred, there are at least tens of thousands of stable configurations.Comment: The final publication is available at Springer via http://dx.doi.org/10.1007/s10955-015-1245-

Monostatic and Bistatic Radar Measurements of Birds and Micro-drone

This paper analyses the experimental results from recent monostatic and bistatic radar measurements of multiple birds as well as a quadcopter micro-drone. The radar system deployed for these measurements was the UCL developed NetRAD system. The aim of this work is to evaluate the key differences observed by a radar system between different birds and a micro-drone. Measurements are presented from simultaneous monostatic co/cross polarized data as well as co-polar bistatic data. The results obtained show comparable signature within the time domain and a marked difference in the Doppler domain, from the various birds in comparison to the micro-drone. The wing beat properties of the birds are shown for some cases which is a stark contrast to the rotor blade micro-Doppler signatures of the drone

Reclaiming "The Land", restoring "The Garden"? Georgic in the modernist moment and beyond

To scrutinize georgic’s position between progress and tradition, this article will focus on the way those forces become legible in poems composed between the end of the First and Second World Wars. I will examine Vita Sackville-West’s long georgics “The Land” (1926) and The Garden (1946) to argue that they indicate the scope of what is possible in the genre given the challenges of both modernity and modernism. Her poems demonstrate that, in seeking to navigate the changing material and cultural landscapes, the labour of maintaining an imaginative tradition can be both productive and problematic. The article will assess the way Sackville-West positions herself as a writer in relation to the figures of the agricultural labourer and gardener and to the classical tradition, as well as her claims about the language in which georgic can and should be written. Each poem will also be compared to the poetry and criticism of her modernist contemporary T.S. Eliot, with particular reference to “The Waste Land, Four Quartets” and his essay “Tradition and the Individual Talent.” Engaged in a struggle on both agricultural and cultural fronts, “The Land” and “The Garden” are prone to inconsistency and, even by their own standards, failure. But in these failures as well as their successes both poems are committed to finding a way of writing human engagement with the land and literature. As such, they can be instructively read in the present moment to prompt questions about the way we engage with land and language in the Anthropocene, negotiating between competing modes of writing and more broadly between natural and human agency.Para examinar la posición geórgica entre el progreso y la tradición, este artículo se centrará en cómo esas fuerzas se hacen legibles en poemas compuestos entre el final de la Primera y la Segunda Guerra Mundial. Examinaré los largos geórgicos de Vita Sackville-West, “The Land” (1926) y “The Garden” (1946) para argumentar su lugar en el género ante los desafíos, tanto de la modernidad como del modernismo. Sus poemas demuestran que, al navegar por un paisaje cambiante, tanto material como cultural, la labor de mantener una tradición imaginativa es a la vez productiva y problemática. El artículo evaluará cómo Sackville-West se posiciona como escritora en relación con las figuras del trabajador agrícola y el jardinero y con la tradición clásica, así como sus declaraciones sobre el lenguaje en el que el geórgico puede y debe escribirse. Cada poema se comparará también con la poesía y la crítica de su contemporáneo modernista T.S. Eliot, con especial referencia a “The Waste Land, Four Quartets” y su ensayo “Tradition and the Individual Talent”. Comprometidos en un doble frente, agrícola y cultural, “The Land” and “The Garden” tienden a la inconsistencia e, incluso para sus propios estándares, al fracaso. Pero tanto en estos fracasos como en sus éxitos, ambos poemas se comprometen a encontrar una forma de escribir el compromiso humano con la tierra y la literatura. Como tales, pueden leerse de manera instructiva en el momento presente para plantear preguntas sobre cómo nos relacionamos con la tierra y el lenguaje en el Antropoceno, negociando entre modos de escritura que compiten entre sí y, más ampliamente, entre la agencialidad natural y la humana

Feature diversity for optimized human micro-doppler classification using multistatic radar

This paper investigates the selection of different combinations of features at different multistatic radar nodes, depending on scenario parameters, such as aspect angle to the target and signal-to-noise ratio, and radar parameters, such as dwell time, polarisation, and frequency band. Two sets of experimental data collected with the multistatic radar system NetRAD are analysed for two separate problems, namely the classification of unarmed vs potentially armed multiple personnel, and the personnel recognition of individuals based on walking gait. The results show that the overall classification accuracy can be significantly improved by taking into account feature diversity at each radar node depending on the environmental parameters and target behaviour, in comparison with the conventional approach of selecting the same features for all nodes

Gait Classification Based on Micro-Doppler Features

This paper focuses on the classification of human gaits based on micro-Doppler signatures. The micro-Doppler signatures can represent detailed information about the human gaits, which helps in judging the threat of a personnel target. The proposed method consists of three major steps. Firstly, the micro-Doppler signatures are obtained by performing time-frequency analysis on the radar data. Then two micro-Doppler features are extracted from the time-frequency domain. Finally, the one-versus-one support vector machine (SVM) is used to realize multi-class classification. Experiments on real data show that, with the selected features, high classification accuracy of the human gaits of interest can be achieved

Tracing water masses and pollution in the Southern Ocean using neodymium and lead isotopes

Trace elements and their isotopes play a vital role in the ocean as participants in, and tracers of, processes of interest to climate change and environmental pollution. This thesis focuses on the use of isotopic variations in neodymium (Nd) and lead (Pb) to understand the cycling of these elements in the Southern Ocean. Neodymium isotopes have been used as a palaeo-proxy to understand changes in Antarctic Bottom Water (AABW) circulation through time. The biogeochemical processes controlling Nd in seawater, however, remain under-constrained due to a paucity of modern observations in the Southern Ocean. In chapter 2, Nd isotope and rare earth element (REE) data are presented for the Wilkes Land continental margin. In this region, AABW exhibits a distinct εNd signature that is intermediate between Atlantic and Pacific sector AABW. The REE data confirm that the εNd signature is not caused by distinct local continental inputs but by mixing of advected AABW with (modified) Circumpolar Deep Water (CDW). Anthropogenic emissions from mining, smelting and fossil fuel combustion are important sources of oceanic Pb contamination. Seawater Pb isotope data, however, is currently severely limited by analytical challenges such as sample contamination, time-consuming extraction procedures and insufficient instrumental detection limits. In chapter 3, a novel method is presented for the determination of seawater Pb isotope compositions and concentrations. The method encompasses solid-phase extraction of Pb from seawater with Nobias chelate PA-1 resin followed by multi-collector inductively coupled mass spectrometry (MC-ICP-MS) analyses using a 207Pb-204Pb double-spike to correct for instrumental mass discrimination. When compared to an established double-spike procedure that employs thermal ionisation mass spectrometry (TIMS), the results are unbiased by systematic error and demonstrates improved precision for the and the minor 204Pb ratios (by about a factor of 2). In chapter 4, the new method is applied to seawater samples from the Australian sector of the Southern Ocean to assess the sources and processes governing the distribution of Pb in this region. Surface waters exhibit a high fraction of anthropogenic Pb (~30–50%). Reversible scavenging and equilibrium exchange are the dominant processes responsible for the vertical transport of this anthropogenic Pb to deeper waters. These processes may account for ~80% of the observed dissolved Pb isotope in the intermediate depth waters at the Polar Front. Overall, the thesis highlights the essential role that isotope analyses play in deconvolving the processes responsible for the biogeochemical cycling of Nd and Pb in the ocean.Open Acces

Dynamic Hand Gesture Classification Based on Radar Micro-Doppler Signatures

Dynamic hand gesture recognition is of great importance for human-computer interaction. In this paper, we present a method to discriminate the four kinds of dynamic hand gestures, snapping fingers, flipping fingers, hand rotation and calling, using a radar micro-Doppler sensor. Two micro-Doppler features are extracted from the time-frequency spectrum and the support vector machine is used to classify these four kinds of gestures. The experimental results on measured data demonstrate that the proposed method can produce a classification accuracy higher than 88.56%