High-Resolution Microwave Near-Field Imaging Using Resonance Probes

A novel microwave high-resolution near-field imaging technique is proposed and experimentally evaluated in reflectometry imaging scenarios involving planar metal-dielectric structures. Two types of resonance near field probes-a small helix antenna and a loaded subwavelength slot aperture are studied in this paper. These probes enable very tight spatial field localization with the full width at half maximum around one tenth of a wavelength, λ, at λ/100-λ/10 standoff distance. Importantly, the proposed probes permit resonance electromagnetic coupling to dielectric or printed conductive patterns, which leads to the possibility of very high raw image resolution with imaged feature-to-background contrast greater than 10-dB amplitude and 50° phase. In addition, high-resolution characterization of target geometries based on the cross correlation image processing technique is proposed and assessed using experimental data. It is shown that printed elements features with subwavelength size ~λ/15 or smaller can be characterized with at least 10-dB resolution contrast.

Imaging the cool stars in the interacting binaries AE Aqr, BV Cen and V426 Oph

It is well known that magnetic activity in late-type stars increases with increasing rotation rate. Using inversion techniques akin to medical imaging, the rotationally broadened profiles from such stars can be used to reconstruct `Doppler images' of the distribution of cool, dark starspots on their stellar surfaces. Interacting binaries, however, contain some of the most rapidly rotating late-type stars known and thus provide important tests of stellar dynamo models. Furthermore, magnetic activity is thought to play a key role in their evolution, behaviour and accretion dynamics. Despite this, we know comparatively little about the magnetic activity and its influence on such binaries. In this review we summarise the concepts behind indirect imaging of these systems, and present movies of the starspot distributions on the cool stars in some interacting binaries. We conclude with a look at the future opportunities that such studies may provide.

Image, Video and 3D Data Registration: Medical, Satellite and Video Processing Applications with Quality Metrics

Data registration refers to a series of techniques for matching or bringing similar objects or datasets together into alignment. These techniques enjoy widespread use in a diverse variety of applications, such as video coding, tracking, object and face detection and recognition, surveillance and satellite imaging, medical image analysis and structure from motion. Registration methods are as numerous as their manifold uses, from pixel level and block or feature based methods to Fourier domain methods.

This book is focused on providing algorithms and image and video techniques for registration and quality performance metrics. The authors provide various assessment metrics for measuring registration quality alongside analyses of registration techniques, introducing and explaining both familiar and state-of-the-art registration methodologies used in a variety of targeted applications.

Key features:
- Provides a state-of-the-art review of image and video registration techniques, allowing readers to develop an understanding of how well the techniques perform by using specific quality assessment criteria
- Addresses a range of applications from familiar image and video processing domains to satellite and medical imaging among others, enabling readers to discover novel methodologies with utility in their own research
- Discusses quality evaluation metrics for each application domain with an interdisciplinary approach from different research perspectives

Electromagnetic Focusing and Imaging in Stratified Media Using Gradient Phase Profiled Conjugating Lens

High-resolution imaging of a dipole source in stratified medium based on negative refraction is presented in this paper. Compensation of the material parameter contrast at the stratified media interface is achieved using a gradient phase profiled conjugating lens (GPCL). It is shown both analytically and numerically that the phase gradient applied across the GPCL positioned at the interface of vertically stratified media enables a high-quality image of a dipole source in a mirror symmetric position with respect to the lens plane. The analytical closed form expression of the phase gradient function is derived using Huygens-Kirchhoff principle. The result is applicable to media with arbitrary stratification and material parameters, including lossy materials. The mechanism for formation of the dipole image in the stratified medium and aberration due to the dielectric contrast at the interface, particularly electromagnetic loss, is discussed in detail. The efficacy of gradient phase and amplitude aberration compensations mechanisms available through the GPCL is articulated. The results of the study are of importance in a wide range of imaging problems in stratified media for medical, civil, and military applications.

Real-time imaging of novel spatial and temporal responses to photodynamic stress.

Cells subjected to various forms of stress have been shown to induce bystander responses in nontargeted cells, thus extending the stress response to a larger population. However, the mechanism(s) of bystander responses remains to be clearly identified, particularly for photodynamic stress. Oxidative stress and cell viability were studied on the spatial and temporal levels after photodynamic targeting of a subpopulation of EMT6 murine mammary cancer cells in a multiwell plate by computerized time-lapse fluorescence microscopy. In the targeted population a dose-dependent loss of cell viability was observed in accordance with increased oxidative stress. This was accompanied by increased oxidative stress in bystander populations but on different time scales, reaching a maximum more rapidly in targeted cells. Treatment with extracellular catalase, or the NADPH oxidase inhibitor diphenyleneiodinium, decreased production of reactive oxygen species (ROS) in both populations. These effects are ascribed to photodynamic activation of NADPH-oxidase in the targeted cells, resulting in a rapid burst of ROS formation with hydrogen peroxide acting as the signaling molecule responsible for initiation of these photodynamic bystander responses. The consequences of increased oxidative stress in bystander cells should be considered in the overall framework of photodynamic stress.