1,721,070 research outputs found
Internal Bremsstrahlung emission during 32P decay
No full textThe aim of this work is to experimentally investigate the role of Internal Bremsstrahlung (IB) in the decay of 32P, a pure β-emitter with end-point energy of 1.71 MeV and half-life of 14.28 days. IB is a continuous electromagnetic radiation occurring in β-decay, that had been widely studied in the past years. Its contribution, even if appreciable, is neglected in Monte Carlo (MC) simulation as well as in dosimetric and radiation protection calculations. Ionization current measurements were carried out using a well ionization chamber and compared with MC simulations, performed in the GAMOS (GEANT4-based Architecture for Medicine-Oriented Simulations) framework. Two experimental data sets of 32P IB spectra, taken from the literature, were used to model the IB photon spectral distribution and to include IB emission as an additional source term in MC calculation. Without IB, MC simulations underestimate up to about −18% the measured exposure, whereas the inclusion of IB according to either of the two spectra lead to differences of +2% or +8%. Consequently, the IB process is relevant for high-energy pure β-emitters such as 32P, and its contribution should be considered in all the dosimetric and radioprotection calculations
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
Relevance of Internal Bremsstrahlung for estimating the exposure to pure beta emitters
No full textAim/Introduction: β-decay is accompanied by Internal Bremsstrahlung (IB) consisting of the emission of photons showing a continuous energy spectrum. Although theoretical approaches have been developed and several measurements have been carried out for modelling the IB spectral distribution, this process is disregarded in most estimates of exposure to pure βemitters. In our recent work [1], we demonstrated that the contribution of IB to the exposure to a 90Y source can ben worth of consideration. We set up two models for the IB spectral distribution and implemented them in Monte Carlo (MC) simulations to evaluate the absorbed dose in case of external irradiation from liquid sources in vials, both without and with the emission of IB photons. We found that, depending on the chosen model, IB photons can contribute to the total absorbed dose up to 30-
60%.The aim of this study was to compare our MC simulations with radiometric measurements for a 90Y source and to extend the analysis also to other high-energy beta emitters such as 32P. Materials and Methods: We compared radiometric measurements in a well ionization chamber with Monte Carlo simulations for 32P and 90Y. MC setup was preliminarily validated by comparing measurements and simulations for 57Co, 133Ba, 137Cs and 60Co γ-emitters. Measurements were carried out using a commercial radionuclide calibrator and, for each isotope, a vial was filled with a standardized solution. MC simulations were performed using GAMOS. Concerning 32P and 90Y, a first set of MC estimates was obtained by neglecting IB photons; then, IB spectral distribution was properly modelled for each beta emitter and a second set of simulations was run including IB photons. Results: We found that MC estimates deviate up to about -15% from measurements when IB process is disregarded in simulations, while the inclusion of IB photons allows achieving a reasonable agreement thus also giving indications on the appropriate modelling of the IB spectral distribution. The obtained results outline the need to include IB
among the interaction processes to be considered when high-energy pure β-emitters are simulated. Conclusion: IB process is usually neglected when estimating the exposure to pure beta emitters. However, we demonstrated that for high-energy beta emitters such as 90Y and 32P, Internal Bremsstrahlung can play a relevant role for enhancing the absorbed dose values. For some β-emitters, the inclusion of IB in MC simulations deserves, in our opinion, consideration. References: [1] Italiano A., et al. Physica Medica 2020;76:159-65
Relevance of Internal Bremsstrahlung photons from 90Y decay: an experimental and Monte Carlo study
No full textInternal Bremsstrahlung (IB) is a continuous electromagnetic radiation accompanying beta decay; however, this process is not considered in radiation protection studies, particularly when estimating exposure from beta-decaying radionuclides. The aims of the present work are: i) to show that neglecting the IB process in Monte Carlo (MC) simulation leads to an underestimation of the energy deposited in a ionization chamber, in the case of a high-energy pure beta emitter such as Yttrium-90 (90Y), and ii) to determine the most reliable choice of source term for 90Y IB to be used in MC simulations. For this radionuclide, commonly employed in nuclear medicine and radiochemistry applications, experimental data acquired with a well ionization chamber have been compared with Monte Carlo (MC) calculations carried out in the GAMOS framework. Simulations that do not include the effect of the IB process, are found to give results underestimating the experimental values by 12–14%. Consequently, two models for the IB energy spectra, previously described by Italiano et al. [1], have been implemented using MC simulation and a good agreement has been achieved with one of them. We therefore conclude that inclusion of IB process in Monte Carlo simulation packages is advisable for a more accurate and complete treatment of electromagnetic interactions
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
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
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