1,721,050 research outputs found
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
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Increased Resolution in Black and White Film Digitization Utilizing a Narrow Bandpass Light Source
No full textIn an effort to preserve and to provide access to their collections of black and white film negatives, many institutions (museums, libraries, archives, etc) are digitizing these collections. Several international committees were formed to define the needed image quality and created digitization guidelines with specifics for different material types to ensure that collection materials are properly documented and digitally preserved. Current practices for digitizing black and white negatives involve many different technologies, most of which incorporate broad-band "white" light sources. To assist with black and white film digitization image quality improvement efforts and standardizations, the author explores the benefits of utilizing a camera sensor without a
color filter array and differing narrow-band light sources to mitigate image degradation caused by diffraction and chromatic change of focus. This thesis demonstrates that utilizing this technique enhances the optical resolution, or modulation transfer function, of the imaging setup with minimal drawbacks as is discussed in this thesis
Modeling charge collection in x-ray imagers
No full textWe present a TCAD simulation-based investigation of charge transport and charge collection mechanisms of a pinned photodiode pixel for X-ray imaging. Following static simulations to determine the electric-field and potential profiles, charge collection was analyzed with transient numerical simulations. A new, simple and computationally affordable calculation based on the extension of Ramo's theorem to account for carrier diffusion is proposed to estimate the trajectories of the generated carriers and the corresponding currents at the device terminals. The new method is validated and successfully compared to the time-dependent TCAD simulations of a p-i-n diode and a template 3D pinned photodiode
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
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Analysis of the Use of Monoenergetic X-rays in Mammography
No full textThis thesis studies the advantages of monoenergetic X-rays for mammography as a replacement for conventional broad-spectrum X-rays. Monoenergetic X-rays have the potential to enhance image quality with a reduced patient dose, although the extent of this potential is unknown. With the recent development of a practical monoenergetic X-ray source, where the X-rays are generated through X-ray fluorescence, it is prudent to examine their potential benefits.
Monte Carlo Simulations were used in the study to produce images of breast phantoms containing signals (which mimic tumors) using a basic photon physics model. The phantom composition is 50% fibro-glandular/50% adipose tissue and varies in thickness from 3 - 10 cm. Ten signals of different thicknesses (from 1 to 10 mm) within a phantom are composed of 100% fibro-glandular tissue. Contrast-to-noise squared per mean glandular dose was established as the figure of merit (FOM) used to assess the performance of simulation output.
We find that the optimal energy for our simulations varied with breast-phantom thickness and composition and that substantial performance improvements are observed compared to conventional spectral imaging. However, contrast-to-noise squared per mean glandular dose, the selected FOM, has known drawbacks as a performance indicator, with its deficiency in correlating actual signal detectability. Therefore, it is recommended that the study be continued and utilizes the industry standard ideal model observer, Hotelling detectability, as the FOM.Release after 06/01/2024Originally set to release after 2024-01-01; embargo extended to 2024-06-01 per author request on 2023-12-21, Kimberl
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
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Phase Defect Modeling and Testing
No full textAn anomalous phase defect has been observed in a particular type of broadband coating which exhibits a dispersive effect on transmitted imagery, decreasing the perceived contrast at specific wavelengths. This paper provides an overview of coating methods and technology with potential sources of defects and outlines the development of a physical optics defect model based on observed spectral data. Model results are then used to investigate the impact of defect size and position on an image transmitted through the coating as a function of wavelength. Lastly, an overview of a proposed laboratory window screening method is provided, which will screen a coated spare window filter for the presence of defects
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