Radon Projections as Image Descriptors for Content-Based Retrieval of Medical Images

Clinical analysis and medical diagnosis of diverse diseases adopt medical imaging techniques to empower specialists to perform their tasks by visualizing internal body organs and tissues for classifying and treating diseases at an early stage. Content-Based Image Retrieval (CBIR) systems are a set of computer vision techniques to retrieve similar images from a large database based on proper image representations. Particularly in radiology and histopathology, CBIR is a promising approach to effectively screen, understand, and retrieve images with similar level of semantic descriptions from a database of previously diagnosed cases to provide physicians with reliable assistance for diagnosis, treatment planning and research. Over the past decade, the development of CBIR systems in medical imaging has expedited due to the increase in digitized modalities, an increase in computational efficiency (e.g., availability of GPUs), and progress in algorithm development in computer vision and artificial intelligence. Hence, medical specialists may use CBIR prototypes to query similar cases from a large image database based solely on the image content (and no text). Understanding the semantics of an image requires an expressive descriptor that has the ability to capture and to represent unique and invariant features of an image. Radon transform, one of the oldest techniques widely used in medical imaging, can capture the shape of organs in form of a one-dimensional histogram by projecting parallel rays through a two-dimensional object of concern at a specific angle. In this work, the Radon transform is re-designed to (i) extract features and (ii) generate a descriptor for content-based retrieval of medical images. Radon transform is applied to feed a deep neural network instead of raw images in order to improve the generalization of the network. Specifically, the framework is composed of providing Radon projections of an image to a deep autoencoder, from which the deepest layer is isolated and fed into a multi-layer perceptron for classification. This approach enables the network to (a) train much faster as the Radon projections are computationally inexpensive compared to raw input images, and (b) perform more accurately as Radon projections can make more pronounced and salient features to the network compared to raw images. This framework is validated on a publicly available radiography data set called "Image Retrieval in Medical Applications" (IRMA), consisting of 12,677 train and 1,733 test images, for which an classification accuracy of approximately 82% is achieved, outperforming all autoencoder strategies reported on the Image Retrieval in Medical Applications (IRMA) dataset. The classification accuracy is calculated by dividing the total IRMA error, a calculation outlined by the authors of the data set, with the total number of test images. Finally, a compact handcrafted image descriptor based on Radon transform was designed in this work that is called "Forming Local Intersections of Projections" (FLIP). The FLIP descriptor has been designed, through numerous experiments, for representing histopathology images. The FLIP descriptor is based on Radon transform wherein parallel projections are applied in a local 3x3 neighborhoods with 2 pixel overlap of gray-level images (staining of histopathology images is ignored). Using four equidistant projection directions in each window, the characteristics of the neighborhood is quantified by taking an element-wise minimum between each adjacent projection in each window. Thereafter, the FLIP histogram (descriptor) for each image is constructed. A multi-resolution FLIP (mFLIP) scheme is also proposed which is observed to outperform many state-of-the-art methods, among others deep features, when applied on the histopathology data set KIMIA Path24. Experiments show a total classification accuracy of approximately 72% using SVM classification, which surpasses the current benchmark of approximately 66% on the KIMIA Path24 data set

Design with the Desert

Typical development in the American Southwest often resulted in scraping the desert lands of the ancient living landscape, to be replaced with one that is human-made and dependent on a large consumption of energy and natural resources. This transdisciplinary book explores the natural and built environment of this desert region and introduces development tools for shaping its future in a more sustainable way. It offers valuable insights to help promote ecological balance between nature and the built environment in the American Southwest-and in other ecologically fragile regions around the world

Earth Resources. A continuing bibliography with indexes, issue 25, April 1980

The bibliography lists 380 reports, articles, and other documents introduced into the NASA scientific and technical information system between January 1, 1980 and March 31, 1990. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis

Cainozoic evolution and hydrogeology of Lake Lewis Basin, Central Australia

Research in Lake Lewis basin in central Australia has investigated the geology, geomorphology and hydro geology of this intermontane Cainozoic basin that overlies the Proterozoic Arunta Craton. The evolution of the area from before Tertiary basin inception to the present-day has been examined. Observations of the structural architecture of the basin have been integrated with models for intracratonic basin evolution, involving reactivation of ancient basement faults. Prior to basin inception, the Palaeozoic and Mesozoic landscape was a highly irregular topography of steep bedrock ranges, valleys and inselbergs. Analysis of geophysical and sedimentological data has enabled reconstruction of the patterns of Tertiary infill within the 200 m deep basin. Lacustrine sedimentation dominated the Palaeogene, infilling a deep structural trough north of the MacDonnell Ranges. Subsequent sedimentation during the Neogene involved accumulation of thick alluvial fan deposits over the basal clay, with the lacustrine depocentre moved northward to the present site of Lake Lewis. A drying phase occurred towards the end of the Tertiary, when fluvial and lacustrine sediments were calcretised, then silicified. At least 80 m of lacustrine clay, the Anmatyerre Clay, accumulated in Lake Lewis in the Neogene-Pleistocene. This uniform clay was deposited in perennial lakewaters, infilling depressions in the heterogeneous basement topography. The Anmatyerre palaeolake was probably an overflow lake during most of its history, with westward outflow at 570 m AHD (Australian Height Datum). The catchment was evidently highly efficient in delivery of runoff from the mountains to the lake and no depositional breaks are apparent. This lake, at its maximum capacity, was up to 19 m deep and covered an area in excess of 3,000 km² , over 12 times the size of the present playa. The BrunhesMatuyama palaeomagnetic polarity reversal (780 ka) is identified in the Anmatyerre Clay at 8 m depth beneath the playa surface. A major switch in sedimentation style followed the Anmatyerre lacustral phase, with hydrologic closure of the basin during more arid conditions. The Early Tilmouth beds were deposited in a <9 m deep lake, the Tilmouth palaeolake, that extended to the 560 m AHD level and covered an area of >l375 km² , 5.5 times the size of the present playa. Hydro logic closure of the basin and high evaporation rates resulted in accumulation of solutes in the system. Saturation with respect to CaC03 and CaS04.2H20 was reached and large volumes of calcium carbonate (calcrete) and gypsum consequently precipitated in the depocentre. The Early Tilmouth beds progressively interacted with saline groundwaters during variable climatic and hydrologic conditions. The timing of the pivotal switch from the perennial Anmatyerre lacustral phase to the more variable Tilmouth lacustral phase is poorly constrained. Extrapolation from records from analogous monsoon dominated lake basins suggests that deposition of the Anmatyerre Clay may have ceased in the Middle Pleistocene, possibly during the severe Marine Isotope Stage (MIS) 10 glacial period. Much of the overlying Early Tilmouth beds may have been deposited during the MIS 7 interglacial period. Attenuation of the main Tilmouth lacustral phase was followed by a deflationary episode. Resumed lacustrine sedimentation involved more intense interaction with saline groundwaters in a greatly contracted, shallow lake setting, and deposition of the highly gypseous Late Tilmouth beds. This lacustral phase may have occurred during early MIS 5, the last interglacial period. An optically stimulated luminescence (OSL) date from a regional linear dunefield in the basin indicates an episode of dune mobility before 95 ka. Arid periods and the continued dominance of highly saline groundwaters followed the Tilmouth lacustral period at Lake Lewis, heralding playa conditions during the Late Pleistocene. Large volumes of gypsum in the form of thick aeolian sand deposits in playa islands and playa-fringing dunes are a legacy of high groundwater tables, moderate or high recharge, evaporative pumping at the playa and possible episodes of enhanced windiness. Interspersed stable periods and the influence of meteoric waters on playa processes are indicated by gypcretisation of respective gypsum sand units in the playa islands. Widespread quartz dunes across the basin landscape represent a period of maximum aridity, at around 23-21 ka. Subsequent ameliorated climatic conditions are represented by strandlines surrounding Lake Lewis that attest to inundation by floodwaters, and substantial fluvial sedimentation along the creeks. OSL dates indicate that the latter sediments span the period 19 - 0 ka. This latest period in the evolution of the basin is additionally represented by reduction of aeolian activity, major disruption of dunefields by floodwaters, and karstic degradation of calcrete ground. Groundwater evolution since hydrologic closure of the basin has followed a CaC0₃ - CaS0₄.2H₂0 path. Precipitation of large volumes of calcium carbonate and gypsum during various phases in the Quaternary has led to near-depletion of dissolved Ca stores in the system. The present-day brine is enriched in Na-Cl-S0₄ and has a salinity of 210,000 mgL⁻¹ (Total Dissolved Solids). High concentrations of dissolved silica, combined with the availability of a favourable host in the form of karstified calcrete, and continued high evaporation rates have promoted precipitation of large amounts of opaline and chalcedonic silica around the playa. Groundwaters flowing lakeward from the silicified calcrete aureole have consequently become silica-depleted. This has greatly impinged upon the brine composition and on diagenetic processes beneath the playa. The zeolite mineral, analcime, Na(A1Si2)06.H20, is precipitating authigenically in the Anmatyerre Clay in the face of silica-deficient, sodium-enriched brine. These findings have resulted in the first detailed investigation of the formation of zeolites in an Australian salt lake setting. Analysis of diagenetic minerals at Lake Lewis has underscored the importance of the antithetic relationship between active silica precipitation, shoreward, in the playa margins, and active analcime crystallisation lakeward, beneath the playa. Despite being the furthest from the coast of Australia's salt lakes, lying at the southern edge of influence of the Australian monsoon, the research reveals that Lake Lewis has, through long periods of its evolution, been a well-watered and efficient lake basin. Available rainfall continues to be efficiently delivered to the lake in today's semi-arid climatic regime. This is attributed to the orographic influence of the adjacent ranges, the high catchment area to lake area ratio and the centripetal drainage system that feeds the lake directly from the encompassing mountains. Notwithstanding the effective delivery of available rainfall, the lake system evolved to a groundwater dominated regime during the Late Pleistocene and has continued to be substantially governed by groundwater processes. The distinctive diagenetic processes currently operating at the depocentre are driven by both the chemical composition of groundwaters and the intensity of evaporation in the current climatic regime

The marine geology of Mossel Bay, South Africa

Includes bibliographical references.This thesis presents work undertaken to better understand the complex evolution of the terrestrial landscape now submerged by high sea levels offshore of Mossel Bay along the South Coast of South Africa. Three marine geophysical surveys and scuba diving were used to examine evidence of past sea-level fluctuations and interpret geological deposits on the seafloor. Additional geological mapping of coastal outcrops was carried out to link land and sea features and rock samples were dated using Optically Stimulated Luminescence (OSL). Geophysical investigations include a regional seismic survey extending from Still Bay in the west to Buffels Bay in the east out to a maximum water depth of 110 m; a high-resolution investigation of the Mossel Bay shelf using multibeam bathymetry, side-scan sonar and sub-bottom profiling; and a shallow seismic pinger survey of Swartvlei, the most prominent coastal lake in the Wilderness Embayment. This study presents 9 discrete seismic sequences, and describes major offshore geomorphic features such as submerged sea cliffs, palaeo-coastal zones and fluvial systems. Oscillation in sea level between ca. 2.7 and 0.9 Ma likely resulted in the formation of the prominent -45 m terrace, which separates a relatively steep inner from a low-gradient mid shelf. Beach and dune deposits span from Marine Isotope Stage 15 (MIS 15) (582 ka) to Recent based on an age model that integrates OSL ages and the established eustatic sea-level record. The most prominent deposits date from the MIS 6 glacial to MIS 5 interglacial periods and include incised lowstand river channels and regressive aeolianites that extended at least 10 km inland from their associated palaeoshorelines. The MIS 5 deposits include transgressive beachrock, an extensive foreshore unit which prograded on the MIS 5e highstand, and regressive beach and dune deposits on the shelf associated with the subsequent fall in sea level. MIS 4 lowstand incised river channels were infilled with sediment truncated during rapid landward shoreface migration at the MIS 4 termination. Lowenergy, back-barrier MIS 4/3 sediments are preserved as a result of overstepping associated with meltwater pulses of the MIS 2 termination. The MIS 1 sediment wedge comprises reworked sediment and is best developed on the inner shelf. Holocene highstand sedimentation continues to prograde. Accommodation space for coastal deposits is controlled by antecedent drainage pathways and the gradient of the adjacent inner continental shelf. The geological deposits on the emergent shelf indicate a greatly expanded glacial coastal plain that potentially received more rain feeding low-gradient meandering rivers and wetland lakes. These extensive wetland environments provided a rich source of diverse food types which along with abundant marine resources on the shoreline made the Southern Coastal Plain an ideal habitat for our ancestors

Assessing the potential for suffusion in sands using x-ray micro-CT images

Internal erosion is a major safety concern for embankment dams and flood embankments and is the focus of much research internationally. Suffusion is a mechanism of internal erosion which affects gap-graded or broadly graded cohesionless soils and is characterised by selective removal of fine material, leaving behind a coarse material with increased hydraulic conductivity. Early studies on suffusion proposed design criteria based on laboratory testing, and presented conceptual models to explain the results in terms of grain-scale behaviour. The study by Kenney & Lau (1985) identified three criteria for suffusion: 1 – Fine particles must be free to move (mechanical criterion); 2 – Fine particles must be small enough to fit through the void space between coarse particles (geometric criterion); 3 – Fluid flowing through the void space must have sufficient velocity to transport the fine particles (hydraulic criterion). Recent studies have examined the first two criteria using grain-scale models with idealised particles, including analytical models and discrete element models (DEM) with circular or spherical particles. This thesis presents a new methodology, using non-destructive 3D imaging (micro-CT) to characterise the internal microstructure in physical specimens of sands and glass beads. This methodology involved the development of innovative image processing and numerical techniques to quantify unstable particle assemblies and to measure particle size distributions and void constriction size distributions. The new method was validated and was shown to produce good agreement with existing methods for idealised particle configurations, however the results for real sand specimens provided new insights into the effects of particle shape, particle size distribution and density on void constriction sizes. Furthermore, the 3D images of real specimens have provided new insights into the appropriateness of existing conceptual models for gap-graded particle structures. These results were used to critically examine and evaluate existing mechanical and geometric criteria for suffusion. The 3D images showed, qualitatively, that the void structures in sands varied significantly from those in porous rocks – which had been the basis for the majority of existing grain-scale fluid flow models. To examine this issue quantitatively, computational fluid dynamics (CFD) simulations were performed within the 3D images of sands and glass beads, in parallel to laboratory permeameter tests on the same materials. The results presented in this thesis provided entirely new insights into the patterns of fluid flow in sands, they allowed correlations to be made between fluid flow and void constriction sizes and also showed how local velocities varied from volume-average discharge and seepage velocities. This study provides new information to support, clarify and improve upon the current understanding of suffusion, filtration and seepage flows in sands. The detailed methodology and results also highlight issues of great importance to future micro-scale modelling of these phenomena.Open Acces

Earth Resources: A continuing bibliography with indexes

This bibliography lists 623 reports, articles, and other documents introduced into the NASA scientific and technical information system between April 1 and June 30, 1983. Emphasis is placed on the use of remote sensing and geophysical instrumentation in spacecraft and aircraft to survey and inventory natural resources and urban areas. Subject matter is grouped according to agriculture and forestry, environmental changes and cultural resources, geodesy and cartography, geology and mineral resources, hydrology and water management, data processing and distribution systems, instrumentation and sensors, and economic analysis

Research selections 2009.

The important thing in science is not so much to obtain new facts as to discover new ways of thinking about them ~ William Lawrence Bragg. Each day at the Australian Nuclear Science and Technology Organisation (ANSTO) is an opportunity to do just that. The chance to see the world and play a role in shaping that world through the prisms of our science. To build on existing knowledge, discovered knowledge, shared knowledge, all offering profound insights into issues as fundamental as the deepest laws of nature through to the basic human factor of everyday issues including food, water and health. And it is because of those everyday issues that impact ordinary people that ANSTO exists. ANSTO scientists and their collaborators have and continue to discover new information about the way the world works ranging from biology and health through to physics and material science. These discoveries allow for new ways to approach healthcare, our environment and our safety. Through state-of-the-art facilities ANSTO and the international research community advance and contribute to knowledge of how the world works, at the atomic level