13,075 research outputs found

    Image Similarity Metrics in Image Registration

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    Measures of image similarity that inspect the intensity probability distribution of the images have proved extremely popular in image registration applications. The joint entropy of the intensity distributions and the marginal entropies of the individual images are combined to produce properties such as resistance to loss of information in one image and invariance to changes in image overlap during registration. However information theoretic cost functions are largely used empirically. This work attempts to describe image similarity measures within a formal mathematical metric framework. Redefining mutual information as a metric is shown to lead naturally to the standardised variant, normalised mutual information

    Improving Techniques to Study Equine Cervical Mucociliary Clearance

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    Bacterial uterine infections inflict major losses on the equine breeding industry. These infections usually arise from bacteria introduced at breeding. Micro-currents propelled by ciliated cells between the folds of the uterus and cervix have been proposed as a means by which contaminants are expelled. Previous data have shown possible ciliary micro-currents propelling carbon particles, occasionally rotating, through cervical folds. However, adherence to the epithelium may have interfered with movement of carbon in these studies. Therefore, we tested potentially non-adherent substances to reveal ciliary micro-currents on the equine cervix under high magnification video-endoscopy. We hypothesized that polyethylene green microspheres 1 - 5 μm and 50 μm in diameter, would be superior to carbon in revealing micro-currents on the cervical epithelium and that 50 μm hemispherically coated bichromal microspheres would display rotation. A suspension containing these microspheres and carbon was deposited onto the cervix of 5 estrous mares and movement of each type of particle was recorded under high video endoscopy for approximately 10 - 20 minutes. In more than 50% of each video recording the field of view was obscured by camera movement or poor positioning. However, the remainder of the recording contained short segments in which the interactions between the epithelium and particles were observable. All observable segments were then analyzed for the presence or absence of desired (visibility, motion, and rotation) and undesired (aggregation) criteria for each type of particle. Particles were scored for the prevalence of these desired and undesired criteria according to the number of video segments in which they were observed. Data were analyzed by the Kruskal-Wallis test. Backward rotation of bichromal spheres was interpreted as evidence of ciliary activity. Overall, carbon scored equal to or higher than the microspheres, leading to rejection of the hypothesis. Of the microspheres, the bichromal microspheres scored highest overall, but tended to aggregate more than the green microspheres, aggregation being undesirable. Subjective assessment concluded that cervical movement was closely related to respiratory movements of the mare, and that the constantly moving cervical folds helped clear the deposited particles. These data may improve detection of mucociliary clearance in the cervix and uterus and may assist future studies to detect impaired mucociliary clearance in infertile mares

    Review: Virtue Information Literacy: Flourishing in an Age of Information Anarchy

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    Review of Bivens-Tatum, W. (2022). Virtue information literacy: Flourishing in an age of information anarchy. Library Juice Press

    Fidelity metrics for virtual environment simulations based on spatial memory awareness states

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    This paper describes a methodology based on human judgments of memory awareness states for assessing the simulation fidelity of a virtual environment (VE) in relation to its real scene counterpart. To demonstrate the distinction between task performance-based approaches and additional human evaluation of cognitive awareness states, a photorealistic VE was created. Resulting scenes displayed on a headmounted display (HMD) with or without head tracking and desktop monitor were then compared to the real-world task situation they represented, investigating spatial memory after exposure. Participants described how they completed their spatial recollections by selecting one of four choices of awareness states after retrieval in an initial test and a retention test a week after exposure to the environment. These reflected the level of visual mental imagery involved during retrieval, the familiarity of the recollection and also included guesses, even if informed. Experimental results revealed variations in the distribution of participants’ awareness states across conditions while, in certain cases, task performance failed to reveal any. Experimental conditions that incorporated head tracking were not associated with visually induced recollections. Generally, simulation of task performance does not necessarily lead to simulation of the awareness states involved when completing a memory task. The general premise of this research focuses on how tasks are achieved, rather than only on what is achieved. The extent to which judgments of human memory recall, memory awareness states, and presence in the physical and VE are similar provides a fidelity metric of the simulation in question

    Ray model and ray-wave correspondence in coupled optical microdisks

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    We introduce a ray model for coupled optical microdisks, in which we select coupling-efficient rays among the splitting rays. We investigate the resulting phase-space structure and report island structures arising from the ray-coupling between the two microdisks. We find the microdisks's refractive index to influence the phase-space structure and calculate the stability and decay rates of the islands. Turning to ray-wave correspondence, we find many resonances to be directly related to the presence of these islands. We study the relation between the (ray-picture originating) island structures and the (wave-picture originating) spectral properties of resonances, especially the leakiness of the resonances which is represented as the imaginary part of the complex wave vector.Comment: 9 pages, 8 figure

    Temperature dependence of surface stress across an order-disorder transition: p(1x2)O/W(110)

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    Strain relaxations of a p(1x2) ordered oxygen layer on W(110) are measured as a function of temperature across the disordering transition using low-energy electron diffraction. The measured strains approach values of 0.027 in the [1-10] and -0.053 in the [001] direction. On the basis of the measured strain relaxations, we give quantitative information on temperature-dependent surface stress using the results of ab initio calculations. From the surface formation energy for different strains, determined by first-principles calculations, we estimate that surface stress changes from -1.1 for the ordered phase to -0.2N/m for the disordered one along [1-10], and from 5.1 to 3.4 N/m along [001]. Moreover, our observation that the strains scale inversely with domain size confirms that the strain relaxation takes place at the domain boundaries.Comment: 8 pages, 5 figure

    Joint Anglo-Soviet biological surveillance exercise on River Dnieper

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    As one part of an on-going programme concerned with environmental protection as provided for under the terms of a UK/USSR Joint Environmental Protection Agreement signed in London, 21 May 1974, a seminar — ”The elaboration of the scientific basis for monitoring the quality of surface water by hydrobiological indices” was held at Valdai in Russia 12—14 July, 1976. As a continuation of this theme it was agreed that delegations of hydrobiologists from each side should carry out reciprocal visits to carry out comparative field tests on selected systems of biological surveillance in use in the respective countries. In May 1978 a team of British hydrobiologists visited the USSR, under the auspices of the Department of Environment, to carry out joint exercises on the River Dnieper and some tributaries. This paper reports the results of selected methods used by the British side when applied to the conditions found in the River Dnieper
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