Generalized likelihood ratio test for optical subpixel objects’ detection with hypothesis-dependent background covariance matrix

Much interest has arisen in the problem of detecting weak optical subpixel objects in a sequence of images immersed in a heavy homogeneous Gaussian clutter background. In optical systems, the presence of the objects changes the background plus the channel noise covariance matri

Proceedings of the Augmented VIsual Display (AVID) Research Workshop

The papers, abstracts, and presentations were presented at a three day workshop focused on sensor modeling and simulation, and image enhancement, processing, and fusion. The technical sessions emphasized how sensor technology can be used to create visual imagery adequate for aircraft control and operations. Participants from industry, government, and academic laboratories contributed to panels on Sensor Systems, Sensor Modeling, Sensor Fusion, Image Processing (Computer and Human Vision), and Image Evaluation and Metrics

Air-Water Gas Transfer

A more complete understanding of the mechanisms involved in the exchange of gases between the atmosphere and the sea is needed if we are to address various environmental issues, and is essential to improved modeling of global climate. This volume contains selected papers from the Third International Symposium on Air-Water Gas Transfer, held at the University of Heidelberg, in Heidelberg, Germany from July 24-27, 1995. The papers are arranged into seven parts: Physical and Chemical Mechanisms, Waves and Turbulence, Breaking Waves and Bubbles, Measuring Technology, Laboratory Measurements and Facilities, Field Measurements, Remote Sensing, and Global Modeling. Emphasis is given to the transfer of carbon dioxide and other radiatively important gases, reflecting current interest in potential global warming. Breaking waves and the bubbles thereby generated play a prominent role in that regard. Also featured are non-invasive measurement technologies, many of which lend themselves to remote sensing applications. Those interested in chemical engineering, fluid mechanics, hydrology, hydraulics, environmental engineering, water quality engineering, climatology, meteorology, and oceanography will find this work a valuable resource

Modelling the behaviour of granular material on the surface of asteroids and under different gravity conditions (e.g., Mars, the Moon)

This thesis, at the interface between the scientific disciplines of planetary science and granular physics, has two key components, both of which intend to increase our understanding of granular dynamics in varying gravitational conditions. The dynamics of granular materials are involved in the evolution of solid planets and small bodies in our Solar System, whose surfaces are generally covered with regolith. Understanding granular dynamics is also critical for the design and/or operations of landers, sampling devices and rovers to be included in space missions. The first component of this thesis is the validation of the hard-sphere discrete element method implementation in the N-body code pkdgrav to model the dynamics of granular material. By direct comparison with results from laboratory experiments, it is demonstrated that the hard-sphere discrete element method implementation in pkdgrav is valid for modelling granular material in dilute regimes and is capable of reproducing the complex dynamical behaviour of a specific dense system as well. The second component is focussed on the AstEx parabolic flight experiment. This experiment, with the aim of characterising the response of granular material to rotational shear forces in a microgravity environment, was designed, constructed, flown and the data were analysed as part of this thesis. It was found that the effect of constant shearing on a granular material in a direction perpendicular to the gravity field is not strongly influenced by gravity. The AstEx experiment has demonstrated, for the first time, that the efficiency of granular convection may decrease in the presence of a weak gravitational field, similar to that on the surface of small bodies. The first measurements of transient weakening of granular material after shear reversal in microgravity are also reported. Results suggest that the force contact network may be weaker in microgravity, although the influence of any change in the contact network is felt by the granular material over much larger distances. This may have important implications for our interpretation of asteroid surfaces. Continued advancement of our understanding of granular materials in varying gravitational conditions requires futher experiments and the development of the soft-sphere discrete element method implementation in pkdgrav in order to model the granular regimes that are inaccessbile to the hard-sphere implementation

Development and characterisation of synthetic model lipid membranes under linear and non-linear microscopy.

Lipid domains provide a framework for localised functionality of the cellular membrane through transient coordination of certain lipids and membrane proteins into structurally distinct, stabilised heterogeneous membrane regions. Present experimental studies fall short of conclusively proving lipid domain existence within the plasma membrane due to the lack of label-free, chemically sensitive nanoscale detection. Herein, I present my progress towards developing novel, label-free optical microscopy techniques to over- come these limitations. Giant unilamellar vesicles (GUVs) represent a simple model of cellular membranes and are well suited for the study of lipid domains. In this thesis, I discuss the demonstration of a novel, label free method to directly assess GUV lamellarity: Quantitative differential interference contrast microscopy (qDIC). Under qDIC, a contrast image is produced which encodes the difference in optical phase (hence optical path length) after propagation through two adjacent points of the sample. I show that, with appropriate data analysis applied to qDIC contrast images, we are able to measure membrane lamellarity directly with sub-nm precision. I then demonstrate the application of this method to static synthetic membranes exhibiting lipid domains: Planar Lipid Bilayer Patches (PLBPs). Sub-nm thickness differences (∼9Å) attributable to coexisting lipid domains are resolved and quantified. Overall, these results demonstrate that label free qDIC is a rapid, non-perturbing, sensitive and accurate method, providing an alternative to fluorescence microscopy, for quantitative studies of lipid domains in model membranes. Furthermore, I discuss correlative qDIC and Coherent Anti-Stokes Ra- man scattering microscopy (CARS) of PLBPs with lipid domains. CARS microscopy has emerged in the last decade as a powerful, chemically specific multi-photon imaging method which overcomes the sensitivity and speed limitations of spontaneous Raman scattering, and enables rapid quantitative analysis of lipids label-free. I demonstrate application of broadband hyper-spectral CARS imaging over the CH 2,3 stretching vibrational resonances, combined with in-house developed phase-corrected Kramers Krönig (PCKK) analysis, which allowed us to resolve and quantify the chemical components of lipid domains at the single bilayer level. Stimulated Raman loss (SRL) microscopy is an alternative, chemically specific, non-linear imaging modality recently implemented within our research group. In contrast to CARS microscopy, SRL rejects non-resonant background providing high contrast imaging of single lipid bilayers comparable to fluorescence imaging. I demonstrate early application of SRL at the single bilayer level across the CH 2,3 stretch region. During this project a number of notable achievements have been made. A novel qDIC method has been developed and utilised. CARS microscopy has been applied to determine lipid liquid phase at both single frequency and hyper-spectral imaging modalities. SRL microscopy has then been applied, demonstrating superior contrast to that seen under CARS. These studies form the foundation for further chemically specific investigation