1,720,962 research outputs found
Benchmarking human performance in semi-automated image segmentation
No full textSemi-automated segmentation algorithms hold promise for improving extraction and identification of objects in images such as tumors in medical images of human tissue, counting plants or flowers for crop yield prediction or other tasks where object numbers and appearance vary from image to image. By blending markup from human annotators to algorithmic classifiers, the accuracy and reproducability of image segmentation can be raised to very high levels. At least, that is the promise of this approach, but the reality is less than clear. In this paper, we review the state-of-the-art in semi-automated image segmentation performance assessment and demonstrate it to be lacking the level of experimental rigour needed to ensure that claims about algorithm accuracy and reproducability can be considered valid. We follow this review with two experiments that vary the type of markup that annotators make on images, either points or strokes, in tightly controlled experimental conditions in order to investigate the effect that this one particular source of variation has on the accuracy of these types of systems. In both experiments, we found that accuracy substantially increases when participants use a stroke-based interaction. In light of these results, the validity of claims about algorithm performance are brought into sharp focus, and we reflect on the need for a far more control on variables for benchmarking the impact of annotators and their context on these types of systems.Mathematics of Information Technology and Complex Systems (MITACS) Globallink Progra
Spine segmentation in computed tomography images using geometric flows and shape priors
No full textSurgical treatment of spine-related injuries requires the placement of pedicle screws. Precise localization of the individual vertebrae and surrounding tissues is thus essential toavoid damage to nearby regions. Image-guided surgery can help in surgical planning andthus improve prognosis. During surgery, preoperative patient scans are registered to intraoperative scans which allows surgeons to track the location of the surgical toolsand better visualize their position with respect to the actual anatomy. In this thesis, wepresent a semi-automated pipeline to segment the human spinal column in computed tomography scans. These segmented anatomical structures wouldthus act as a model to which the intraoperative scans are later registered. We incorporate ashape prior into geometric active contours to augment the segmentation produced using region andboundary based terms. We have also applied ideas based on anisotropic diffusion and fluxcomputation to preprocess the volumes to address the challenges faced when working with CT scans, such as region inhomogeneities within and outside the spine and a lack of signalat the vertebral boundaries due to partial volume effects. We validateour approach on three datasets and achieve results comparable to the state of the art. Our method alsoprovides good localization and segmentation of the spinal canal and intervertebral discs as offshoots.Les opérations chirurgicales des lésions de la colonne vertébrale nécessitent la mise en place de vis pédiculaires. Localiser précisément les vertèbres et les tissus environnants est donc indispensable pour éviter dendommager les régions voisines. Guider le chirurgien par l’image aide à la planification chirurgicale et améliore donc le pronostic. Pendantl’opération, des scans préopératoires des patients sont recalés sur des images captées en direct, ce qui permet aux chirurgiens de localiser leurs outils et mieux visualiser leur position par rapport à l’anatomie du patient. Dans cette thése, nous présentons un processus semi-automatisé pour segmenter des scanners de tomodensitométrie et en extraire la colonne vertébrale. Ainsi segmentées, ces structures peuvent alors servir de modéle pour un recalage futur au moment de l’opération. Nous utilisons des contours géométriques actifs, s’appuyant sur la détection des contours, des régions, et utilisant une connaissance a priori de ces formes afin d’affiner la segmentation. Nous avons également utilisé des principes de la diffusion anisotrope et de calculs de flux afin de prétraiter les volumes. En effet, il s’agit de répondre aux défis usuels de la tomodensitométrie, comme par exemple l’hétérogénéité à l’intérieur et à l'extérieur de la colonne vertébrale ou les perturbations liées à la limite de résolution. Nous validons notre approche sur trois jeux de données et nous obtenons des résultats comparables à l’état de l’art. De notre méthode découle aussi une bonne localisation et une bonne segmentation du canal rachidien et des disques intervertébraux
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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