1,721,023 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
Evaluation of Thallium Bromide as a Room Temperature Gamma-ray Detector
Get PDFGamma-ray spectroscopy is a common non-destructive assay method used in the identification and characterisation of radioactive samples at nuclear sites. Room temperature semiconductor detectors (RTSD) are often deployed for portable gamma-ray detection during nuclear decommissioning. Thallium bromide (TlBr) is a novel RTSD which offers enhanced sensitivity over competing materials, such as cadmium zinc telluride (CZT), due to its increased atomic number and density. However, the longevity of TlBr devices is limited by ionic polarization of the crystal when an external bias is applied, which leads to the corrosion of the metal electrodes. The work reported here aimed to develop TlBr devices with metal oxide contacts to suppress the polarization effect and extend device lifetime.
Monte Carlo simulations, using the Geant4 toolkit, were used to compare the sensi- tivity of TlBr and CZT devices to gamma-rays with energies of interest to nuclear assay (0 to 1.4 MeV). It was found that gamma-rays within this energy range typically penetrate much further into the CZT crystal whilst undergoing a larger fraction of multiple scatter- ing events. It was also shown that TlBr sensors with dimensions of 1.0 × 1.0 × 0.4 cm3 were as efficient at detecting 662.0 keV gamma-rays compared to 1.0 × 1.0 × 1.0 cm3 of CZT. These results were used to inform the design of devices used in experimental studies.
A suite of thin TlBr samples were fabricated by the author with In, indium tin oxide (ITO) and SnO2 electrodes. The samples underwent X-ray photoelectron spectroscopy (XPS) and it was established, using the Kraut method of band alignment, that a type II staggered heterojunction formed at the metal oxide/TlBr interfaces. Current-voltage measurements determined that these contacts acted Ohmically in the ranges ± 100 V and that they had very low leakage currents. Due to the fact that metal oxides are less reactive than pure metals, and because of their comparable electronic behaviour, metal oxides may be used in place of metal as contacts on TlBr radiation detectors.
Finally, In and ITO contacted TlBr devices (with dimensions 1.0 × 1.0 × 0.4 cm3) were fabricated by scientists at CapeSym, Inc. and underwent radiometric testing by the author at the University of Liverpool. The noise sensitivity of both detectors was increased by a voltage dependent electric field breakdown, which may have been caused by the polarisation phenomena. Both detectors displayed a range of signal amplitudes after being exposed to Cs-137 radiation, suggesting that charge had not been completely collected. This is most likely because the saturation voltage could not be reached before the electric field breakdown, as well as the presence of trapping centers within the crystal bulk. Energy spectra was collected for the In/TlBr device during irradiation from Cs-137 and Na-22 source. The full energy photopeak could not be resolved, but the shifting Compton edge illustrated the energy sensitivity of the device. These findings demonstrate that this thesis’ technique for developing energy sensitive TlBr detectors was successful. However, further work needs to be taken to improve charge collection within TlBr detectors and to compare the spectral response of metal and metal oxide contacted devices
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
Electrical properties of Cadmium Telluride Thin Film Solar Cells Activated with Magnesium Chloride
Get PDFDispelling 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
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