1,720,953 research outputs found
DETERMINATION OF PATIENT SPECIFIC S-VALUES CORRELATED WITH NONINVASIVE PATIENT ATTRIBUTES
No full textIntroduction: Nuclear medicine procedures are the second largest source of medical ionizing radiation, behind only computed tomography. The current population has been exposed to medical imaging more than previous generations, therefore knowledge of absorbed dose (ionizing) is not only an important component of patient care, but may have epidemiological implications as well. Unlike other modalities, in nuclear medicine a clinician can often decrease the patient’s administered activity at the expense of extending the acquisition time, administration therefore is not a binary decision . It should be noted radionuclide dosimetry can be accurately calculated if sufficient data is available. However, in most cases crucial information such as uptake, biokinetics and anatomical details cannot or will not be known a priori. Furthermore, the dosimetric process is often arduous, requiring intensive resources with respect to personnel and technology. Convenient models based on MIRD formalism have been developed to overcome the aforementioned challenges. Unfortunately, the models are not patient specific which causes inaccuracies, one such shortcoming centers around spatial variances. In the MIRD schema S values denote the mean absorbed dose to a target volume (organ) per unit activity in a source region (organ). The S values are based on phantom models for specific radionuclides, in the MIRD schema they are separable from the kinetic aspects of nuclear medicine. To improve patient specific nuclear medicine dosimetry S values will be determined for patients directly. The analysis will be conducted for radionuclides of interest and select organs. The range of organ S values will be examined to determine the need of personalization and its possible benefit. The results will be benchmarked against modern phantom models (dosimetric software), with the goal of personalizing phantom results through the utilization of basic patient attributes.
Methods: To evaluate the variances between the S-values of patients and phantoms, one needs diagnostic images. The gold standard modality of anatomical imaging is computed tomography. Fifty-six patient computed tomography exams were made available by the National Institutes of Health (NIH), along with information regarding the patient’s sex, age, height and weight. The patient images were de-identified prior, the clinical images contained the structures of the Chest, Abdomen and Pelvis of persons. The diagnostic images (CT) were segmented by TotalSegmentator which is a deep learning model, resulting in various structures. These structures were used to in part to create a source distribution and a lattice model for Monte Carlo implementation. The source energies and yields regarding emission was obtained from ICRP 107. Radiation transport is one of the areas that has greatly benefited from Monte Carlo methods. The Monte Carlo simulations conducted in this work utilize MCNP 6.2 which is a general-purpose, continuous-energy, generalized-geometry, time-dependent, Monte Carlo radiation transport code. The S values were calculated for a number of target organs (spleen, kidneys, pancreas, stomach, liver and lungs) resulting from activity in the patient’s kidneys for (Tc-99m, F-18, Lu-177 and I-131). The results were compared and benchmarked versus NCINM a modern dosimetry program based in part on phantom models. Results: The variation of S values for adult target organs were found to significant. The variation between the minimum and maximum S values for patients ranged from a two-fold to a five-fold factor and therefore supports the need for personalization. Benchmarking the S values with NCINM revealed in most cases the phantoms were contained within the patient’s distribution if not centered, which adds to the simulation’s credibility. The patient specific values were normalized to their appropriate NCINMphantom models. Significant correlation was found between the patient’s BMI and their normalized S values irrespective of radionuclide. The correlation is believed to be due to internal shielding. Based on a linear fit the NCINM model was extended or personalized. This extension greatly reduced the variation between actual S values and the NCINM dosimetry model. The interquartile range of the distribution of most organ S values were decreased by 50 percent
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
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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