1,857 research outputs found

    Compact multi-aperture imaging with high-angular-resolution

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    Previous reports have demonstrated that it is possible to emulate the imaging function of a single conventional lens with an NxN array of identical lenslets to provide an N-fold reduction in imaging-system track length. This approach limits the application to low-resolution imaging. We highlight how using an array of dissimilar lenslets, with an array width that can be much wider than the detector array, high-resolution super-resolved imaging is possible. We illustrate this approach with a ray-traced design and optimization of a long-wave infrared system employing a 3x3 array of free-form lenslets to provide a four-fold reduction in track length compared to a baseline system. Simulations of image recovery show that recovered image quality is comparable to that of the baseline system

    Multi-aperture foveated imaging

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    Foveated imaging, such as that evolved by biological systems to provide high angular resolution with a reduced space–bandwidth product, also offers advantages for man-made task-specific imaging. Foveated imaging systems using exclusively optical distortion are complex, bulky, and high cost, however. We demonstrate foveated imaging using a planar array of identical cameras combined with a prism array and superresolution reconstruction of a mosaicked image with a foveal variation in angular resolution of 5.9:1 and a quadrupling of the field of view. The combination of low-cost, mass-produced cameras and optics with computational image recovery offers enhanced capability of achieving large foveal ratios from compact, low-cost imaging systems

    An Investigation into Geocapability and Future 3 Curriculum Thinking in Geography

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    This thesis explores the extent to which the concept of the ‘capability approach’ can be applied to thinking about the value, aims and outcomes of a geography education. ‘Geocapability’ articulates the extent to which the powerful knowledge of geography is an essential component of a school geography curriculum. The thesis includes an empirical study of geography departments in two contrasting schools. Through interviews with teachers, pupils, parents, school leaders and governors, an understanding was gained about the way teachers view the curriculum, and the considerations and influences on their work. A teacher workshop was held to provide an insight into the ‘curriculum making’ process. Analysis of the data indicated that there was a variety of views of the aims of education, the significance of knowledge within it and the responsibility teachers have for the curriculum content. Discussion of the data identified that geocapability can provide a structured way for teachers to conceptualise a geography curriculum as it links broad educational aims, with geography as powerful knowledge to pupil outcomes in terms of life choices. The thesis makes an original contribution to the field of geography education in a number of ways. Although a capability approach is familiar in several fields within education studies this is the first that links capabilities with the subject curriculum. It is the first school-based empirical study into geocapability which has helped to further and refine the concept. A conceptual model of geocapability is proposed to structure curriculum thinking for school geography teachers which enables teachers to conceptualise a knowledge led geography curriculum with broader educational aims and outcomes. A practical curriculum planning tool, the geocapability ‘Framework’ is developed, tested and presented to help teachers ensure that powerful geographical knowledge is at the heart of a geography curriculum

    Tertiary Coal Resources, Eastern Arctic Archipelago

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    CINENet: deep learning-based 3D cardiac CINE MRI reconstruction with multi-coil complex-valued 4D spatio-temporal convolutions

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    Cardiac CINE magnetic resonance imaging is the gold-standard for the assessment of cardiac function. Imaging accelerations have shown to enable 3D CINE with left ventricular (LV) coverage in a single breath-hold. However, 3D imaging remains limited to anisotropic resolution and long reconstruction times. Recently deep learning has shown promising results for computationally efficient reconstructions of highly accelerated 2D CINE imaging. In this work, we propose a novel 4D (3D + time) deep learning-based reconstruction network, termed 4D CINENet, for prospectively undersampled 3D Cartesian CINE imaging. CINENet is based on (3 + 1)D complex-valued spatio-temporal convolutions and multi-coil data processing. We trained and evaluated the proposed CINENet on in-house acquired 3D CINE data of 20 healthy subjects and 15 patients with suspected cardiovascular disease. The proposed CINENet network outperforms iterative reconstructions in visual image quality and contrast (+ 67% improvement). We found good agreement in LV function (bias ± 95% confidence) in terms of end-systolic volume (0 ± 3.3 ml), end-diastolic volume (- 0.4 ± 2.0 ml) and ejection fraction (0.1 ± 3.2%) compared to clinical gold-standard 2D CINE, enabling single breath-hold isotropic 3D CINE in less than 10 s scan and ~ 5 s reconstruction time

    A versatile panel of reference gene assays for the measurement of chicken mRNA by quantitative PCR

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    Quantitative real-time PCR assays are widely used for the quantification of mRNA within avian experimental samples. Multiple stably-expressed reference genes, selected for the lowest variation in representative samples, can be used to control random technical variation. Reference gene assays must be reliable, have high amplification specificity and efficiency, and not produce signals from contaminating DNA. Whilst recent research papers identify specific genes that are stable in particular tissues and experimental treatments, here we describe a panel of ten avian gene primer and probe sets that can be used to identify suitable reference genes in many experimental contexts. The panel was tested with TaqMan and SYBR Green systems in two experimental scenarios: a tissue collection and virus infection of cultured fibroblasts. GeNorm and NormFinder algorithms were able to select appropriate reference gene sets in each case. We show the effects of using the selected genes on the detection of statistically significant differences in expression. The results are compared with those obtained using 28s ribosomal RNA, the present most widely accepted reference gene in chicken work, identifying circumstances where its use might provide misleading results. Methods for eliminating DNA contamination of RNA reduced, but did not completely remove, detectable DNA. We therefore attached special importance to testing each qPCR assay for absence of signal using DNA template. The assays and analyses developed here provide a useful resource for selecting reference genes for investigations of avian biology
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