1,720,964 research outputs found
Simulation of gamma-ray shielding properties for materials of medical interest
No full textRadiation that is emitted from unstable nuclei during radioactive decay is an important phenomenon to be used in large fields, and thus, radiation shielding properties are important especially for gamma rays. Thus, in the present work, the radiation shielding properties in terms of linear attenuation coefficients and some other quantities for medical interest materials of water, fat and bone have been obtained. The results simulated by Phy-X/PSD online code the energy range of 10(-3)-10(5) MeV
Radiation dose measurement on bone scintigraphy and planning clinical management
No full textRadiation has been used in a variety of different fields since its discovery. It is very important in medial sector for both diagnosis and also for treatment. In this study, the radiation dose rate emitted to the environment after radiopharmaceutical injection was determined using patients undergoing bone scintigraphy imaging. Radiation dose rate measurements were performed at different distances from the patient and at different levels of the patient. Measurements were done at different times to determine the relationship between radiation dose rate and time. The radiation dose rate emitted by the patient was measured after an average of 10.21, 42.36, and 76.28 min of injection. In order to see the relationship between radiation dose rate and distance, measurements were done at 25, 50, 100, and 200 cm distance from the patient. The measured average radiation dose rate at 1 m distance from the patients' chest level and 10.21 min after radiopharmaceutical injection was 16.27 mu Sv h(-1). Then, the average radiation dose rate decayed down to 13.65 mu Sv h(-1) after 42.36 min, while the measured average radiation dose rate after 76.28 min was lower as 12.41 mu Sv h(-1) at 100 cm from patient's chest level
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Full text linkWe 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
An extensive study on the neutron-gamma shielding and mass stopping power of (70-x) CRT-30K<sub>2</sub>O-xBaO glass system for <SUP>252</SUP>Cf neutron source
No full textakkurt, iskender/0000-0002-5247-7850;The present study focuses on the charged-uncharged particles shielding performance of the addition of a mixed type of cathode ray tube (CRT) in a glass system that is irradiated by the Cf-252 neutron source via the MCNPX simulation and analytical calculations, as well as Phy-X: PSD and SRIM software. The CRT waste glass is inserted into the glass system with (70-x) CRT-30K(2)O-xBaO general formula for x = 0, 10, 20 mol% that produces CG1, CG2, and CG3 glass shielding materials. Using Watt Fission Distribution (WFD) and Doppler Effect (DE) the neutron-gamma photon spectra were extracted for shielded (in the presence of the glass materials) and unshielded (in air) cases. Some calculated attenuation parameters related to the neutron deduced that CG1 is the best neutron attenuator among the selected glass samples. Moreover, by increasing the density of the glass from CG1 to CG3, the ascending trend is observed for the linear attenuation coefficient (LAC, cm(-1)) of the studied glass, and the best shielding competence is monitored for CG3. Furthermore, two sharp peaks are found in Z(eff) graphs which may be due to K-edge absorption of Ba and Pb elements and by decreasing the Pb element from CG1 to CG3 the second peak gradually becomes smooth. In addition, Mass Stopping Power/ Projected Ranges of the proton (H-1) and alpha particles (He+2) are also estimated by SRIM code and findings show that CG1 can better stop proton and alpha particles in comparison with the other chosen glass structures
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