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The human eye can distinguish as many as 10,000 different colours but is far less sensitive to variations in intensity1, meaning that colour is highly desirable when interpreting images. However, most biological samples are essentially transparent, and nearly invisible when viewed using a standard optical microscope2. It is therefore highly desirable to be able to produce coloured images without needing to add any stains or dyes, which can alter the sample properties. Here we demonstrate that colorimetric histology images can be generated using full-sized plasmonically active microscope slides. These slides translate subtle changes in the dielectric constant into striking colour contrast when samples are placed upon them. We demonstrate the biomedical potential of this technique, which we term histoplasmonics, by distinguishing neoplastic cells from normal breast epithelium during the earliest stages of tumorigenesis in the mouse MMTV-PyMT mammary tumour model. We then apply this method to human diagnostic tissue and validate its utility in distinguishing normal epithelium, usual ductal hyperplasia, and early-stage breast cancer (ductal carcinoma in situ). The colorimetric output of the image pixels is compared to conventional histopathology. The results we report here support the hypothesis that histoplasmonics can be used as a novel alternative or adjunct to general staining. The widespread availability of this technique and its incorporation into standard laboratory workflows may prove transformative for applications extending well beyond tissue diagnostics. This work also highlights opportunities for improvements to digital pathology that have yet to be explored.

The invention of phase contrast microscopy revolutionized optics, enabling the visualization of highly optically transparent samples without the need for staining. The technique utilizes phase shifts within the sample and is routinely employed in the characterization of biological material and other weakly interacting objects. However, the demand for increased contrast and quantification has continued to drive research into more advanced approaches to phase imaging. Here, we demonstrate that the combination of ptychographic coherent diffractive imaging with plasmonically active metamaterials yields a massive enhancement of both the reconstructed phase and amplitude by exploiting near-field interactions at the metamaterial surface. We present results from nanofabricated samples and tissue sections with thickness ranging from 4 nm to 4 μm. In addition to enabling quantitative phase imaging of metamaterials, this approach opens the way to imaging a wide range of extremely thin or highly transparent objects previously inaccessible to optical microscopy.

Here we report the results of shear-mode thicknesses and absorption coefficient measurements made on neat membranes using scanning near-field optical microscopy (SNOM). Biomimic neat membranes composed of two different types of phoshpholipid molecules: 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1,2- dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) were found to exhibit different absorption coefficients under the SNOM. The localization of the lipids could be identified and correlated to the morphology of the membrane domains indicating that SNOM can be an effective and accurate approach for the label-free characterization of the structure-function relationships in cell membranes.

Characterising and understanding the mechanisms involved in cell death are especially important to combating threats to human health, particularly for the study of antimicrobial peptides and their effectiveness against pathogenic fungi. However, imaging these processes often relies on the use of synthetic molecules which bind to specific cellular targets to produce contrast. Here we study yeast cell death, induced by the anti-fungal peptide, NaD1. By treating yeast as a model organism we aim to understand anti-fungal cell death processes without relying on sample modification. Using a quantitative phase imaging technique, ptychography, we were able to produce label free images of yeast cells during death and use them to investigate the mode of action of NaD1. Using this technique we were able to identify a significant phase shift which provided a clear signature of yeast cell death. Additionally, ptychography identifies cell death much earlier than a comparative fluorescence study, providing new insights into the cellular changes that occur during cell death. The results indicate ptychography has great potential as a means of providing additional information about cellular processes which otherwise may be masked by indirect labelling approaches.

The spatial resolution of diffractive imaging techniques depends upon the numerical aperture of the detected scatter rather than any image forming optics. Fresnel coherent diffractive imaging has been developed over the past decade as a means for examining regions of interest within continuous samples and for overcoming many of the stagnation issues traditionally associated with coherent diffractive imaging. Ptychography meanwhile has been developed independently as a method of reconstructing the transmission function of extended objects from diffraction data recorded using a sequence of multiple overlapping probes on the sample. The relatively recent combination of these two methods has been found to provide substantial benefits over either of the two techniques when applied separately. The experimental requirements and basic principles of ptychographic Fresnel diffraction tomography are reviewed in this paper.

The advent of (sub)microscopic focused X-ray beams at third generation synchrotron sources has opened up possibilities for the characterisation of material structure and mechanical behaviour with unprecedented spatial resolution. Crucially, the non-destructive nature and fast rate of X-ray data collection allow in situ deformation to be studied. In this review, we concentrate on the inelastic deformation response of ductile metallic (poly)crystals. We describe a range of diffraction-based techniques we have developed including monochromatic beam reciprocal space mapping, scanning “pink” beam micro-diffraction compound topography, and white beam Laue micro-diffraction. We compare the results obtained using each of the above techniques, and assess and review the insights that they afford into micro-scale material deformation.

Predicting the fatigue lifetime of components relies on a knowledge of the residual elastic strain present throughout the bulk of the material. Non-destructively mapping the complete strain distribution throughout large volumes presents significant practical challenges. Recently a technique known as Bragg-edge neutron transmission has been developed as a means of non-destructive bulk elastic strain evaluation. Whilst conventional radiography measures the integral absorption, Bragg-edge neutron transmission probes the average strain along the incident beam direction. A “strain radiogram” is thus a two-dimensional average projection of the strain within the sample. Here we demonstrate how strain radiograms can be used for “neutron strain tomography” and we present and contrast two different approaches to the problem of characterising spatially resolved elastic strains.

For high performance, safety-critical applications, such as aerospace components, in-depth understanding of the material's response to complex loading conditions is essential. Moreover, it is vital to know how the material behaviour may be modified as a consequence of fatigue loading and how its eventual failure occurs. Unlike bulk properties, such as stiffness, yield stress, etc. that depend on the average response of the grains in a polycrystal, material failure is determined by “weakest link” type mechanisms. These depend strongly on grain-level deformation behaviour and grain-to-grain interactions. Micro-beam Laue diffraction is a powerful tool to probe these phenomena. However, the classical setup is limited to the study of sample surface regions or thin sections, due to the limited penetration into the sample at photon energies of 5 – 25 keV. A much more useful tool for the material scientist and engineer would allow the probing of grain-level orientation and stress in thicker sections of engineering components. To this end, we have developed the high energy transmission Laue (HETL) technique, an extension of the micro-beam Laue technique to significantly higher photon energies (50 – 150 keV). For the imaging of lattice orientation and elastic strain in three dimensions, we propose two alternative approaches: Laue orientation tomography (LOT) and high energy differential aperture X-ray microscopy (HEDAXM). In this paper an overview of the recent progress in HETL, LOT and HEDAXM measurements will be given and some first results illustrating the potential of these techniques presented.

Methods for imaging cellular architecture and ultimately macromolecular complexes and individual proteins, within a cellular environment, are an important goal for cell and molecular biology. Coherent diffractive imaging CDI is a method of lensless imaging that can be applied to any individual finite object. A diffraction pattern from a single biological structure is recorded and an iterative Fourier transform between real space and reciprocal space is used to reconstruct information about the architecture of the sample to high resolution. As a test system for cellular imaging, we have applied CDI to an important human pathogen, the malaria parasite, Plasmodium falciparum. We have employed a novel CDI approach, known as Fresnel CDI, which uses illumination with a curved incident wavefront, to image red blood cells infected with malaria parasites. We have examined the intrinsic Xray absorption contrast of these cells and compared them with cells contrasted with heavy metal stains or immunogold labeling. We compare CDI images with data obtained from the same cells using scanning electron microscopy, light microscopy, and scanning Xray fluorescence microscopy. We show that CDI can offer new information both within and at the surface of complex biological specimens at a spatial resolution of better than 40 nm. and we demonstrate an imaging modality that conveniently combines scanning Xray fluorescence microscopy with CDI. The data provide independent confirmation of the validity of the coherent diffractive image and demonstrate that CDI offers the potential to become an important and reliable new highresolution imaging modality for cell biology. CDI can detect features at high resolution within unsectioned cells. © 2008 International Society for Advancement of Cytometry

The study of business and politics is attracting new interest, perhaps due to changing configurations of power in Western societies undergoing rapid but uneven structural and cultural change. Previous debates have demonstrated the inadequacy of the pressure group model, primarily because of its insensitivity to the socio-economic foundations of power and the significance of the cultural context. This paper reviews the approach proposed by Charles E. Lindblom's Politics and Markets, examines some attempts to refine that approach and advances some criticisms of a general methodological nature. It is suggested that neo-marxist perspectives are more likely than post-pluralist ones to be able to comprehend the articulation of agency and context, or behaviour and structure. A concluding section points to the relative paucity of Australian work on business and politics, notes the contributions of Connell and Irving and Tsokhas, and suggests that the increasingly important and volatile field of banking and finance has been especially neglected.

The threads of business, charity and sentiment have always been tangled in the provision of student housing; although the mix of these has varied depending on whether the dominant provider has been the churches, the State or the market. This paper reviews some major studies of student housing; provides an introductory survey of its development and levels of current provision in Australia; reviews some of the supply and financing issues which student housing presently confronts; and conjectures on the evolution of government policy. The formative role student housing can play and the educational support it can provide may be important, especially in a period when higher education is becoming a narrower and more utilitarian experience, but not always a more satisfying one.