See a list of publications below or visit the Photonics academic staff page and click on a particular  member of staff to access their personal web page, which includes a list of their own publications.

Search or filter publications

Filter by type:

Filter by publication type

Filter by year:

to

Results

  • Showing results for:
  • Reset all filters

Search results

  • Journal article
    Garcia E, Hayden A, Birts C, Britton E, Cowie A, Pickard K, Mellone M, Choh C, Derouet M, Duriez P, Noble F, White MJ, Primrose JN, Strefford JC, Rose-Zerilli M, Thomas GJ, Ang Y, Sharrocks AD, Fitzgerald RC, Underwood TJ, MacRae S, Grehan N, Abdullahi Z, de la Rue R, Noorani A, Elliott RF, de Silva N, Bornschein J, ODonovan M, Contino G, Yang T-P, Chettouh H, Crawte J, Nutzinger B, Edwards PAW, Smith L, Miremadi A, Malhotra S, Cluroe A, Hardwick R, Davies J, Ford H, Gilligan D, Safranek P, Hindmarsh A, Sujendran V, Carroll N, Turkington R, Hayes SJ, Ang Y, Preston SR, Oakes S, Bagwan I, Save V, Skipworth RJE, Hupp TR, ONeill JR, Tucker O, Taniere P, Owsley J, Crichton C, Schusterreiter C, Barr H, Shepherd N, Old O, Lagergren J, Gossage J, Davies A, Chang F, Zylstra J, Sanders G, Berrisford R, Harden C, Bunting D, Lewis M, Cheong E, Kumar B, Parsons SL, Soomro I, Kaye P, Saunders J, Lovat L, Haidry R, Eneh V, Igali L, Welch I, Scott M, Sothi S, Suortamo S, Lishman S, Beardsmore D, Anderson C, Smith ML, Secrier M, Eldridge MD, Bower L, Achilleos A, Lynch AG, Tavare Set al., 2016,

    Authentication and characterisation of a new oesophageal adenocarcinoma cell line: MFD-1

    , Scientific Reports, Vol: 6, Pages: 32417-32417, ISSN: 2045-2322

    New biological tools are required to understand the functional significance of genetic events revealed by whole genome sequencing (WGS) studies in oesophageal adenocarcinoma (OAC). The MFD-1 cell line was isolated from a 55-year-old male with OAC without recombinant-DNA transformation. Somatic genetic variations from MFD-1, tumour, normal oesophagus, and leucocytes were analysed with SNP6. WGS was performed in tumour and leucocytes. RNAseq was performed in MFD-1, and two classic OAC cell lines FLO1 and OE33. Transposase-accessible chromatin sequencing (ATAC-seq) was performed in MFD-1, OE33, and non-neoplastic HET1A cells. Functional studies were performed. MFD-1 had a high SNP genotype concordance with matched germline/tumour. Parental tumour and MFD-1 carried four somatically acquired mutations in three recurrent mutated genes in OAC: TP53, ABCB1 and SEMA5A, not present in FLO-1 or OE33. MFD-1 displayed high expression of epithelial and glandular markers and a unique fingerprint of open chromatin. MFD-1 was tumorigenic in SCID mouse and proliferative and invasive in 3D cultures. The clinical utility of whole genome sequencing projects will be delivered using accurate model systems to develop molecular-phenotype therapeutics. We have described the first such system to arise from the oesophageal International Cancer Genome Consortium project.
  • Conference paper
    Chakraborty BK, Bhuyan MK, Kumar S, 2016,

    Adaptive propagation-based skin segmentation method for color images

    Segmentation of skin regions from color images has many important Computer Vision applications. But, accuracy of existing skin detection methods are severely affected by the color similarity between the background and actual skin regions. Probabilistic approaches using skin probability maps (SPMs) can solve this problem to an extent. In this paper, a novel method has been proposed which uses seeded region growing method. Region growing is implemented by an adaptive cost propagation and neighborhood analysis scheme. The initial seeds are obtained from the SPM. It is observed from the experimental results that the proposed method can perform better compared to the existing skin segmentation methods for different illumination and background conditions.
  • Conference paper
    Kumar S, Bhuyan MK, Chakraborty BK, 2016,

    An efficient face model for facial expression recognition

    Existing facial expression recognition (FER) algorithms aim to extract discriminative features from a face. These discriminative features can be extracted only from the informative regions of a face. In this view, several face models are proposed which are mainly intended to extract geometrical features from a face, and hence these models may not be suitable for extract discriminative texture features from a face. We proposed a novel face model based on projection analysis of a face. Our proposed projection analysis evaluates the distribution of informative regions of a face. This is done by projecting the expressive face images onto their corresponding neutral images. Hence, the proposed face model can efficiently extract distinctive texture features from a face. Additionally, the proposed face model can extract geometrical features as well. The performance of the proposed face model is evaluated on MUG datasets which shows that the proposed face model outperforms several existing face models. Also, the proposed face model can give a recognition accuracy of 97.3% which is significantly better than the performance of state-of-the-art face models.
  • Journal article
    Kumar S, Bhuyan MK, Chakraborty BK, 2016,

    Extraction of informative regions of a face for facial expression recognition

    , Iet Computer Vision, Vol: 10, Pages: 567-576, ISSN: 1751-9632

    The aim of facial expression recognition (FER) algorithms is to extract discriminative features of a face. However, discriminative features for FER can only be obtained from the informative regions of a face. Also, each of the facial subregions have different impacts on different facial expressions. Local binary pattern (LBP) based FER techniques extract texture features from all the regions of a face, and subsequently the features are stacked sequentially. This process generates the correlated features among different expressions, and hence affects the accuracy. This research moves toward addressing these issues. The authors' approach entails extracting discriminative features from the informative regions of a face. In this view, they propose an informative region extraction model, which models the importance of facial regions based on the projection of the expressive face images onto the neural face images. However, in practical scenarios, neutral images may not be available, and therefore the authors propose to estimate a common reference image using Procrustes analysis. Subsequently, weighted-projection-based LBP feature is derived from the informative regions of the face and their associated weights. This feature extraction method reduces miss-classification among different classes of expressions. Experimental results on standard datasets show the efficacy of the proposed method.
  • Journal article
    Murphy L, French P, Waters A, Clement WA, Kubba Het al., 2016,

    Dorsal midline tongue masses in children

    , INTERNATIONAL JOURNAL OF PEDIATRIC OTORHINOLARYNGOLOGY EXTRA, Vol: 13, Pages: 40-43, ISSN: 1871-4048
  • Conference paper
    Lepert G, Gouveia RM, Connon CJ, Paterson Cet al., 2016,

    High-resolution imaging of limbal structural properties using Brillouin spectro-microscopy

    , Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404
  • Conference paper
    Gore DM, French P, O'Brart D, Dunsby C, Allan BDSet al., 2016,

    NC-1059 peptide-assisted transepithelial riboflavin penetration in an ex-vivo rabbit corneal model

    , Annual Meeting of the Association-for-Research-in-Vision-and-Ophthalmology (ARVO), Publisher: ASSOC RESEARCH VISION OPHTHALMOLOGY INC, ISSN: 0146-0404
  • Journal article
    Chennell G, Willows RJW, Warren SC, Carling D, French PMW, Dunsby C, Sardini Aet al., 2016,

    Imaging of Metabolic Status in 3D Cultures with an Improved AMPK FRET Biosensor for FLIM

    , Sensors, Vol: 16, ISSN: 1424-8239

    We describe an approach to non-invasively map spatiotemporal biochemical and physiological changes in 3D cell culture using Forster Resonance Energy Transfer (FRET) biosensors expressed in tumour spheroids. In particular, we present an improved Adenosine Monophosphate (AMP) Activated Protein Kinase (AMPK) FRET biosensor, mTurquoise2 AMPK Activity Reporter (T2AMPKAR), for fluorescence lifetime imaging (FLIM) readouts that we have evaluated in 2D and 3D cultures. Our results in 2D cell culture indicate that replacing the FRET donor, enhanced Cyan Fluorescent Protein (ECFP), in the original FRET biosensor, AMPK activity reporter (AMPKAR), with mTurquoise2 (mTq2FP), increases the dynamic range of the response to activation of AMPK, as demonstrated using the direct AMPK activator, 991. We demonstrated 3D FLIM of this T2AMPKAR FRET biosensor expressed in tumour spheroids using two-photon excitation.
  • Conference paper
    Kinsler P, Gratus J, McCall MW, Thompson RTet al., 2016,

    Dispersion in space-time transformation optics

    , URSI International Symposium on Electromagnetic Theory (EMTS), Publisher: IEEE, ISSN: 2163-405X

    The use of spacetime cloaking to hide events is an intriguing trick, but the unavoidable presence of dispersion limits the performance of any implementation, and needs to be accounted for. We show how the dispersion changes under transformation.
  • Journal article
    Carter IE, Weir K, McCall MW, Parker ARet al., 2016,

    Variation in the circularly polarized light reflection of Lomaptera (Scarabaeidae) beetles

    , Journal of the Royal Society Interface, Vol: 13, ISSN: 1742-5689

    An extended spectroscopic study on the left-through-left circularly polarised reflection spectra of a large number of beetles from the Australasian Scrabaeidae:Cetoniinae of the Lomaptera genus was undertaken. We have obtained a five-category spectral classification.The principal spectral features, which even within the genus range from blue to infra-red, are related to structural chirality in the beetle shells. The detailed features of each spectral classification are related to different structural perturbations of the helix including various pitch values and abrupt twist defects. These spectral characteristics and associated shell structures are confirmed on the basis of simple modelling. An important conclusion from our study is that the simple helical structure resulting in a single symmetric Bragg peak is not thedominant spectral type. Rather the reality is a rich tapestry of spectral types. One intriguing specimen is identified via an SEM micrograph to consist of a double interstitial helix leadingto a particular double-peak spectrum.
  • Conference paper
    Friddin MS, Bolognesi G, Elani Y, Brooks N, Law R, Seddon J, Neil M, Ces Oet al., 2016,

    The optical assembly of bilayer networks from cell-sized droplets for synthetic biology

    , Systems and Synthetic Biology
  • Journal article
    Margineanu A, Chan JJ, Kelly DJ, Warren S, Flatters D, Kumar S, Katan M, Dunsby C, French PMWet al., 2016,

    Screening for protein-protein interactions using Förster resonance energy transfer (FRET) and fluorescence lifetime imaging microscopy (FLIM)

    , Scientific Reports, Vol: 6, ISSN: 2045-2322

    We present a high content multiwell plate cell-based assay approach to quantify protein interactions directly in cells using Förster resonance energy transfer (FRET) read out by automated fluorescence lifetime imaging (FLIM). Automated FLIM is implemented using wide-field time-gated detection, typically requiring only 10 s per field of view (FOV). Averaging over biological, thermal and shot noise with 100’s to 1000’s of FOV enables unbiased quantitative analysis with high statistical power. Plotting average donor lifetime vs. acceptor/donor intensity ratio clearly identifies protein interactions and fitting to double exponential donor decay models provides estimates of interacting population fractions that, with calibrated donor and acceptor fluorescence intensities, can yield dissociation constants. We demonstrate the application to identify binding partners of MST1 kinase and estimate interaction strength among the members of the RASSF protein family, which have important roles in apoptosis via the Hippo signalling pathway. KD values broadly agree with published biochemical measurements.
  • Journal article
    Rutter GA, Semplici F, Mondragon A, Macintyre B, Madeyski-Bengston K, Persson-Kry A, Ramne A, Marley A, McGinty J, French P, Soedling H, Yokosuka R, Gaiten J, Lang J, Migrenne-Li S, Philippe E, Herrera PL, Magnan C, da Silva Xavier Get al., 2016,

    Cell type-specific deletion in mice reveals roles for PAS kinase in insulin and glucagon production

    , Diabetologia, Vol: 59, Pages: 1938-1947, ISSN: 1432-0428

    Background and Aims. Per-Arnt-Sim domain containing kinase (PASK) is a nutrient regulated protein kinase previously implicated in the control of insulin gene expression and glucagon secretion. Here, we explore the roles of the kinase in the control of islet hormone release by generating mice deleted selectively for the Pask gene in pancreatic beta or alpha cells. Methods. Floxed alleles of Pask were produced by homologous recombination and animals bred with mice bearing beta (Ins1Cre, PaskBKO), or alpha (PPG-Cre; PaskAKO) cell selective Cre recombinase alleles. Glucose homeostasis and hormone secretion in vivo and in vitro, gene expression, and islet cell mass, were measured using standard techniques.Results. Ins1Cre-based recombination led to efficient beta cell targeted deletion of Pask. Beta cell mass was reduced by 36.5% (p<0.05) compared to controls in PaskBKO mice, as well as in global null Pask mice (38%, p<0.05). PaskBKO mice displayed normal body weight and fasting glycemia, but slightly impaired glucose tolerance, and beta cell proliferation, after maintenance on a high fat diet. Whilst glucose tolerance was unaffected in PaskAKO mice, glucose infusion rates were increased, and glucagon secretion tended to be lower, during hypoglycemic clamps. Though alpha cell mass was increased (21.9%, p<0.05), glucagon release at low glucose was impaired (p<0.05) in PaskAKO islets. Conclusions. The present findings demonstrate cell autonomous roles for PASK in the control of pancreatic endocrine hormone secretion. Differencesbetween the glycemic phenotype of global versus cell type specific null mice suggest important roles for tissue interactions in the control of glycemia by the kinase.
  • Conference paper
    Murray RT, Runcorn TH, Kelleher EJR, Guha S, Taylor JRet al., 2016,

    Mid-Infrared Difference Frequency-Generation with Synchronized Fiber Lasers

    , Advanced Solid State Lasers
  • Conference paper
    Murray RT, Runcorn TH, Kelleher EJR, Taylor JRet al., 2016,

    Watt-level Nanosecond 589 nm Source by SHG of a Cascaded Raman Amplifier

    , Advanced Solid State Lasers 2016
  • Journal article
    Taylor JR, 2016,

    Tutorial on fiber-based sources for biophotonic applications

    , Journal of Biomedical Optics, Vol: 21, ISSN: 1560-2281

    Fiber-based lasers and master oscillator power fiber amplifier configurations are described. These allow spectral versatility coupled with pulse width and pulse repetition rate selection in compact and efficient packages. This is enhanced through the use of nonlinear optical conversion in fibers and fiber-coupled nonlinear crystals, which can be integrated to provide all-fiber pump sources for diverse application. The advantages and disadvantages of sources based upon supercontinuum generation, stimulated Raman conversion, four-wave mixing, parametric generation and difference frequency generation, allowing spectral coverage from the UV to the mid-infrared, are considered.
  • Journal article
    Goodacre R, Sergo V, Barr H, Sammon C, Schultz ZD, Baker MJ, Graham D, Marques MP, Sulé-Suso J, Livermore J, Faulds K, Sinjab F, Matousek P, Campbell CJ, Dluhy R, Gardner P, Phillips C, Diem M, Wood B, Apolonskiy A, Kazarian S, Fullwood L, Gough K, Petrich W, Lloyd G, Ibrahim O, Cinque G, Sockalingum GD, Stone N, Kendall C, McAughtrie S, Perez-Guaita D, Clark L, Gerwert K, Bonifacio A, Notingher I, Lasch P, Bhargava R, Lepert G, Mader K, Paterson Cet al., 2016,

    Clinical Spectroscopy: general discussion

    , Faraday Discussions, Vol: 187, Pages: 429-460, ISSN: 1364-5498
  • Conference paper
    Kumar S, Bhuyan MK, 2016,

    Neutral expression modeling in feature domain for facial expression recognition

    , Pages: 224-228

    Facial expression recognition (FER) is an active pattern recognition problem in the field of computer vision. The objective of FER algorithms is to extract discriminative features from a face. From the Ekman's theory, any expression is a result from deviation of their neutral state. So, the analysis of expressive images with respect to neutral expression could be important for facial expression recognition. However, neutral images of different subjects comprise large variability in shapes as well as in texture. Hence, alignment is a primary step to minimize shape and texture variations of neutral images of different subjects. We propose to align neutral images of different subjects in the feature domain using Procrustes analysis. Subsequently, modeling of shape-free neutral images is done using Principal Component Analysis (PCA). Projection of expressive image onto the neutral subspace helps to divide an image into two components namely neutral component and expressive component. Proposed method extracts features from both the components. Extracted features are divided into a number of blocks and subsequently, dimensionality of each block is reduced with multiple discriminant analysis (MDA). The reduced feature is used to train supervised support vector machine (SVM) classifier. Experimental results show the efficacy of the proposed approach.
  • Conference paper
    Woodward RI, Murray RT, Phelan CF, de Oliveira REP, Li S, Eda G, de Matos CJSet al., 2016,

    Characterization of the nonlinear susceptibility of monolayer MoS2 using second- and third-harmonic generation microscopy

    , CLEO:2016 Laser Science to Photonic Applications, Publisher: OSA, Pages: STu1R.3-STu1R.3

    Second- and third-harmonic generation microscopy of monolayer MoS2 is reported for imaging and characterization of the material's nonlinearity. A telecommunication wavelength pump is used, revealing the material's promise for use in nonlinear optical devices.
  • Conference paper
    Friddin MS, Bolognesi G, Elani Y, Brooks N, Law R, Seddon J, Neil M, Ces Oet al., 2016,

    Optical tweezers to assemble 2D and 3D droplet interface bilayer networks from cell-sized droplets

    , EMBL Microfluidics
  • Journal article
    Lepert G, Gouveia RM, Connon CJ, Paterson Cet al., 2016,

    Assessing corneal biomechanics with Brillouin spectro-microscopy

    , Faraday Discussions, Vol: 187, Pages: 415-428, ISSN: 1364-5498

    A new Brillouin spectro-microscope was designed and built to investigate the mechanical properties of bovine and human corneas. This instrument integrates a single-stage virtually imaged phased array spectrometer with a novel adaptive-optics interferometric filter to achieve unprecedented rejection of the elastic background signal. As a result, highly-resolved, reproducible data from both thin and thick collagen-based materials were obtained. In particular, this technique is capable of rigorously measuring the relative stiffness of different areas of human corneas, thus providing a true non-contact method to characterise the fundamental mechanical features of both live and fixed biological tissue samples.
  • Journal article
    Kumar S, Lockward N, Ramel M-C, Correia T, Ellis M, Alexandrov Y, Andrews N, Patel R, Bugeon L, Dallman M, Brandner S, Arridge S, Katan M, McGinty J, Frankel P, French PMWet al., 2016,

    Quantitative in vivo optical tomography of cancer progression & vasculature development in adult zebrafish

    , Oncotarget, Vol: 7, Pages: 43939-43948, ISSN: 1949-2553

    We describe a novel approach to study tumour progression and vasculature development in vivo via global 3-D fluorescence imaging of live non-pigmented adult zebrafish utilising angularly multiplexed optical projection tomography with compressive sensing (CS-OPT). This “mesoscopic” imaging method bridges a gap between established ~μm resolution 3-D fluorescence microscopy techniques and ~mm-resolved whole body planar imaging and diffuse tomography. Implementing angular multiplexing with CS-OPT, we demonstrate the in vivo global imaging of an inducible fluorescently labelled genetic model of liver cancer in adult non-pigmented zebrafish that also present fluorescently labelled vasculature. In this disease model, addition of a chemical inducer (doxycycline) drives expression of eGFP tagged oncogenic K-RASV12 in the liver of immune competent animals. We show that our novel in vivo global imaging methodology enables non-invasive quantitative imaging of the development of tumour and vasculature throughout the progression of the disease, which we have validated against established methods of pathology including immunohistochemistry. We have also demonstrated its potential for longitudinal imaging through a study of vascular development in the same zebrafish from early embryo to adulthood. We believe that this instrument, together with its associated analysis and data management tools, constitute a new platform for in vivo cancer studies and drug discovery in zebrafish disease models.
  • Journal article
    Murray RT, Runcorn TH, Kelleher EJR, Taylor JRet al., 2016,

    Highly efficient mid-infrared difference-frequency generation using synchronously pulsed fiber lasers

    , Optics Letters, Vol: 41, Pages: 2446-2449, ISSN: 1539-4794

    We report the development of a high average power, picosecond-pulse, mid-infrared source based on difference-frequency generation (DFG) of two synchronous master oscillator power fiber amplifier systems. The generated idler can be tuned over the range 3.28–3.45 μm delivering greater than 3.4 W of average power, with a maximum pump to total DFG power conversion efficiency of 78%. The benefits of a synchronously pumped scheme, compared to CW seeding of DFG sources, are discussed.
  • Journal article
    Arbabzadah EA, Damzen MJ, 2016,

    Fibre-coupled red diode-pumped Alexandrite TEM00 laser with single and double-pass end-pumping

    , Laser Physics Letters, Vol: 13, ISSN: 1612-202X

    We report the investigation of an Alexandrite laser end-pumped by a fibre-coupled red diode laser module. Power, efficiency, spatial, spectral, and wavelength tuning performance are studied as a function of pump and laser cavity parameters. It is the first demonstration, to our knowledge, of greater than 1 W power and also highest laser slope efficiency (44.2%) in a diode-pumped Alexandrite laser with diffraction-limited TEM00 mode operation. Spatial quality was excellent with beam propagation parameter M 2 ~ 1.05. Wavelength tuning from 737–796 nm was demonstrated using an intracavity birefringent tuning filter. Using a novel double pass end-pumping scheme to get efficient absorption of both polarisation states of the scrambled fibre-delivered diode pump, a total output coupled power of 1.66 W is produced in TEM00 mode with 40% slope efficiency.
  • Journal article
    Kim Y, Warren SC, Stone JM, Knight JC, Neil MAA, Paterson C, Dunsby CW, French PMWet al., 2016,

    Adaptive Multiphoton Endomicroscope Incorporating a Polarization-Maintaining Multicore Optical Fibre

    , IEEE Journal of Selected Topics in Quantum Electronics, Vol: 22, ISSN: 1558-4542

    We present a laser scanning multiphoton endomicroscopewith no distal optics or mechanical components that incorporatesa polarization-maintaining (PM) multicore optical fibre todeliver, focus, and scan ultrashort pulsed radiation for two-photonexcited fluorescence imaging. We show theoretically that the use ofa PM multicore fibre in our experimental configuration enhancesthe fluorescence excitation intensity achieved in the focal spot comparedto a non-PM optical fibre with the same geometry and con-firm this by computer simulations based on numerical wavefrontpropagation. In our experimental system, a spatial light modulator(SLM) is utilised to program the phase of the light input to each ofthe cores of the endoscope fibre such that the radiation emergingfrom the distal end of the fibre interferes to provide the focusedscanning excitation beam. We demonstrate that the SLM can enabledynamic phase correction of path-length variations across themulticore optical fibre whilst the fibre is perturbed with an updaterate of 100 Hz.
  • Conference paper
    Maioli V, Gorlitz F, Warren S, Kumar S, French PMW, Chennell G, Sardini A, Carling D, Alwes F, Dunsby CWet al., 2016,

    Three-dimensional fluorescence imaging by stage-scanning oblique plane microscopy

    , Conference on Three-Dimensional and Multidimensional Microscopy - Image Acquisition and Processing XXIII, Publisher: SPIE, ISSN: 0277-786X
  • Journal article
    Andrews N, Ramel M-C, Kumar S, Alexandrov Y, Kelly DJ, Warren SC, Kerry L, Lockwood N, Frolov A, Frankel P, Bugeon L, McGinty J, Dallman MJ, French PMWet al., 2016,

    Visualising apoptosis in live zebrafish using fluorescence lifetime imaging with optical projection tomography to map FRET biosensor activity in space and time

    , Journal of Biophotonics, Vol: 9, Pages: 414-424, ISSN: 1864-0648

    Fluorescence lifetime imaging (FLIM) combined with optical projection tomography (OPT) has the potential to map Förster resonant energy transfer (FRET) readouts in space and time in intact transparent or near transparent live organisms such as zebrafish larvae, thereby providing a means to visualise cell signalling processes in their physiological context. Here the first application of FLIM OPT to read out biological function in live transgenic zebrafish larvae using a genetically expressed FRET biosensor is reported. Apoptosis, or programmed cell death, is mapped in 3-D by imaging the activity of a FRET biosensor that is cleaved by Caspase 3, which is a key effector of apoptosis. Although apoptosis is a naturally occurring process during development, it can also be triggered in a variety of ways, including through gamma irradiation. FLIM OPT is shown here to enable apoptosis to be monitored over time, in live zebrafish larvae via changes in Caspase 3 activation following gamma irradiation at 24 hours post fertilisation. Significant apoptosis was observed at 3.5 hours post irradiation, predominantly in the head region.
  • Conference paper
    McCall MW, 2016,

    Transformation optics, curvature and beyond (Conference Presentation)

    , Conference on Metamaterials X, Publisher: Society of Photo-optical Instrumentation Engineers (SPIE), ISSN: 1996-756X

    Although the transformation algorithm is very well established and implemented, some intriguing questions remain unanswered. 1) In what precise mathematical sense is the transformation optics algorithm ‘exact’? The invariance of Maxwell’s equations is well understood, but in what sense does the same principle not apply to acoustics (say)? 2) Even if the fields are transformed in a way that apparently mimic vacuum perfectly, it is easy to construct very simple examples where the impedance of the transformed medium is no longer isotropic and homogeneous. This would seem to imply a fundamental shortcoming in any claim that electromagnetic cloaking has been reduced to technology. 3) Transformations are known to exist that introduce a discrepancy between the Poynting vector and the wave-vector. Does this distinction carry any physical significance? We have worked extensively on understanding a commonality between transformation theories that operates at the level of rays – being interpreted as geodesics of an appropriate manifold. At this level we now understand that the *key* problem underlying all attempts to unify the transformational approach to disparate areas of physics is how to relate the transformation of the base metric (be it Euclidean for spatial transformation optics, or Minkowskian for spacetime transformation optics) to the medium parameters of a given physical domain (e.g. constitutive parameters for electromagnetism, bulk modulus and mass density for acoustics, diffusion constant and number density for diffusion physics). Another misconception we will seek to address is the notion of the relationship between transformation optics and curvature. Many have indicated that transformation optics evinces similarities with Einstein’s curvature of spacetime. Here we will show emphatically that transformation optics cannot induce curvature. Inducing curvature in an electromagnetic medium requires the equivalent of a gravitational sou
  • Conference paper
    Andrews N, Ramel MC, Kumar S, Alexandrov Y, Kelly DJ, Warren SC, Kerry L, Lockwood N, Frolov A, Frankel P, Bugeon L, McGinty J, Dallman MJ, French PMWet al., 2016,

    Fluorescence lifetime optical projection tomography and FRET applied to visualizing apoptosis in live zebrafish larvae

    We present the application of FLIM-OPT to read out biological function in live transgenic zebrafish larvae using a genetically expressed cleavable FRET biosensor for Caspase-3 as an indicator of gamma radiation induced apoptosis.
  • Conference paper
    Watson TJ, Andrews N, Harry E, Bugeon L, Dallman MJ, French PMW, McGinty Jet al., 2016,

    Remote focal scanning and sub-volume optical projection tomography

    We present a platform for sub-volume optical projection tomography utilising an electrically tunable lens and tracking technology. Applied to 3D fluorescent bead phantoms and zebrafish embryos, we demonstrate an improvement in resolution and light collection efficiency with respect to conventional optical projection tomography.

This data is extracted from the Web of Science and reproduced under a licence from Thomson Reuters. You may not copy or re-distribute this data in whole or in part without the written consent of the Science business of Thomson Reuters.

Request URL: http://www.imperial.ac.uk:80/respub/WEB-INF/jsp/search-t4-html.jsp Request URI: /respub/WEB-INF/jsp/search-t4-html.jsp Query String: id=211&limit=30&resgrpMemberPubs=true&page=13&resgrpMemberPubs=true&respub-action=search.html Current Millis: 1771761079715 Current Time: Sun Feb 22 11:51:19 GMT 2026