1,720,955 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
Astronomical Catalogue Cross Identification for Data Mining and Statistical Analysis of the Infrared and Faint Radio Sky
No full textCross-identifying complex radio sources with optical or infrared counterparts in surveys such as the Australia Telescope Large Area Survey (ATLAS) has traditionally been performed by a visual inspection of individual sources. However, with new surveys from the Australian Square Kilometre Array Pathfinder detecting many tens of million of radio sources such an approach is no longer feasible. The Likelihood Ratio (LR) allows the use of additional data about survey objects to be cross matched rather than just position and proximity, such as flux, probability distribution and catalogue surface density. This thesis presents a new software algorithm (LRPY - Likelihood Ratio in PYthon) to automate the process of cross-identifying radio sources with catalogues at other wavelengths using the LR. I demonstrate LRPY by applying it to the ATLAS Data Release 3 and a Spitzer-based multi-wavelength catalogue, identifying 3,848 cross matched sources using my LR-based selection criteria. I found that LRPY could be extended to identify radio sources with multiple infrared counterparts many of which I identify as interacting galaxy pairs. In addition I also investigated if LRPY could be used to select radio sources with more complex morphology, such as double lobe radio sources. This extension to the algorithm is shown to work well in identifying the host of many double lobe radio sources. A subset of 1987 cross matched sources in this thesis have flux density values for all four bands in the Spitzer/IRAC instrument, which allowed me to use various criteria to distinguish between active galactic nuclei (AGN) and star-forming galaxies (SFG). I found that 936 radio sources (≈47%) meet both of the Lacy and Stern AGN selection criteria. Of the matched sources, 295 have spectroscopic redshifts and we examine the radio to infrared flux ratio vs redshift, proposing an AGN selection criterion below the Elvis radio-loud (RL) AGN limit for this dataset. Taking the union of all three AGN selection criteria I have identified 956 cross matched sources as AGN (≈48%). From this dataset, we find a decreasing fraction of AGN with lower radio flux densities consistent with other results in the literature. I found there is a strong power law correlation demonstrated using the complete Fusion dataset seen in the AGN arm of the MIR [3.6]-[5.8] vs [4.5]-[8.0] plot for the LACY AGN selection wedge, but there was no such strong correlation for the Stern AGN wedge of the MIR [5.8]-[8.0] vs [3.6]-[4.5] colour-colour plot. Due to this I have analysed the cross matched sources in this thesis for a power law relationship, it was apparent that for the MIR [3.6]-[5.8] vs [4.5]-[8.0] colour-colour plots used for Lacy AGN selection the correlation between the AGN candidate infrared flux ratios to the power-law locus is very strong in the AGN arm. The Stern MIR colour-colour criteria [5.8]-[8.0] vs [3.6]-[4.5] shows no strong correlation for the AGN candidate infrared flux ratios to the power-law locus for the cross matched sources. I have also looked at the relationship between the MIR 8.0µm to radio 1.4GHz relationship, there is a clear distinction between AGN and SFG's. I have also looked at the relationship between the Radio L₁.₄GHz and MIR luminosities L₃.₆µm and L₄.₅µm, as prior work had provided existence of a correlation. What was found is that the higher redshift sources (z>0.3) lie within the top right quadrant of the plots, when the Stern and Lacy AGN are identified we see the majority of these AGN also lie within this same quadrant. Looking at the AGN selected sources we see a slope close to unity at both MIR wavelengths, for 3.6µm the slope is m = 1.004 ± 0.155 and at 4.5µm it was found to be m = 0.980 ± 0.153. I conclude the thesis by summarizing the work and discussing future work to be undertaken as a result of the research
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
Development of Very Long Baseline Interferometry (VLBI) techniques in New Zealand: Array simulation, image synthesis and analysis
No full textThis thesis presents the design and development of a process to model Very Long Base Line Interferometry (VLBI) aperture synthesis antenna arrays. In line with the Auckland University of Technology (AUT) Institute for Radiophysics and Space Research (IRSR) aims to develop the knowledge, skills and experience within New Zealand, extensive use of existing radio astronomical software has been incorporated into the process namely AIPS (Astronomical Imaging Processing System), MIRIAD (a radio interferometry data reduction package) and DIFMAP (a program for synthesis imaging of visibility data from interferometer arrays of radio telescopes). This process has been used to model various antenna array configurations for two proposed New Zealand sites for antenna in a VLBI array configuration with existing Australian facilities and a passable antenna at Scott Base in Antarctica; and the results are presented in an attempt to demonstrate the improvement to be gained by joint trans-Tasman VLBI observation. It is hoped these results and process will assist the planning and placement of proposed New Zealand radio telescopes for cooperation with groups such as the Australian Long Baseline Array (LBA), others in the Pacific Rim and possibly globally; also potential future involvement of New Zealand with the SKA. The developed process has also been used to model a phased building schedule for the SKA in Australia and the addition of two antennas in New Zealand. This has been presented to the wider astronomical community via the Royal Astronomical Society of New Zealand Journal, and is summarized in this thesis with some additional material. A new measure of quality (“figure of merit”) for comparing the original model image and final CLEAN images by utilizing normalized 2-D cross correlation is evaluated as an alternative to the existing subjective visual operator image comparison undertaken to date by other groups. This new unit of measure is then used in the presentation of the results to provide a quantative comparison of the different array configurations modelled. Included in the process is the development of a new antenna array visibility program which was based on a Perl code script written by Prof Steven Tingay to plot antenna visibilities for the Australian Square Kilometre Array (SKA) proposal. This has been expanded and improved removing the hard coded fixed assumptions for the SKA configuration, providing a new useful and flexible program for the wider astronomical community. A prototype user interface using html/cgi/perl was developed for the process so that the underlying software packages can be served over the web to a user via an internet browser. This was used to demonstrate how easy it is to provide a friendlier interface compared to the existing cumbersome and difficult command line driven interfaces (although the command line can be retained for more experienced users)
Astronomical Catalogue Cross Identification for Data Mining and Statistical Analysis of the Infrared and Faint Radio Sky
No full textCross-identifying complex radio sources with optical or infrared counterparts in surveys such as the Australia Telescope Large Area Survey (ATLAS) has traditionally been performed by a visual inspection of individual sources. However, with new surveys from the Australian Square Kilometre Array Pathfinder detecting many tens of million of radio sources such an approach is no longer feasible. The Likelihood Ratio (LR) allows the use of additional data about survey objects to be cross matched rather than just position and proximity, such as flux, probability distribution and catalogue surface density. This thesis presents a new software algorithm (LRPY - Likelihood Ratio in PYthon) to automate the process of cross-identifying radio sources with catalogues at other wavelengths using the LR. I demonstrate LRPY by applying it to the ATLAS Data Release 3 and a Spitzer-based multi-wavelength catalogue, identifying 3,848 cross matched sources using my LR-based selection criteria. I found that LRPY could be extended to identify radio sources with multiple infrared counterparts many of which I identify as interacting galaxy pairs. In addition I also investigated if LRPY could be used to select radio sources with more complex morphology, such as double lobe radio sources. This extension to the algorithm is shown to work well in identifying the host of many double lobe radio sources. A subset of 1987 cross matched sources in this thesis have flux density values for all four bands in the Spitzer/IRAC instrument, which allowed me to use various criteria to distinguish between active galactic nuclei (AGN) and star-forming galaxies (SFG). I found that 936 radio sources (≈47%) meet both of the Lacy and Stern AGN selection criteria. Of the matched sources, 295 have spectroscopic redshifts and we examine the radio to infrared flux ratio vs redshift, proposing an AGN selection criterion below the Elvis radio-loud (RL) AGN limit for this dataset. Taking the union of all three AGN selection criteria I have identified 956 cross matched sources as AGN (≈48%). From this dataset, we find a decreasing fraction of AGN with lower radio flux densities consistent with other results in the literature. I found there is a strong power law correlation demonstrated using the complete Fusion dataset seen in the AGN arm of the MIR [3.6]-[5.8] vs [4.5]-[8.0] plot for the LACY AGN selection wedge, but there was no such strong correlation for the Stern AGN wedge of the MIR [5.8]-[8.0] vs [3.6]-[4.5] colour-colour plot. Due to this I have analysed the cross matched sources in this thesis for a power law relationship, it was apparent that for the MIR [3.6]-[5.8] vs [4.5]-[8.0] colour-colour plots used for Lacy AGN selection the correlation between the AGN candidate infrared flux ratios to the power-law locus is very strong in the AGN arm. The Stern MIR colour-colour criteria [5.8]-[8.0] vs [3.6]-[4.5] shows no strong correlation for the AGN candidate infrared flux ratios to the power-law locus for the cross matched sources. I have also looked at the relationship between the MIR 8.0µm to radio 1.4GHz relationship, there is a clear distinction between AGN and SFG's. I have also looked at the relationship between the Radio L₁.₄GHz and MIR luminosities L₃.₆µm and L₄.₅µm, as prior work had provided existence of a correlation. What was found is that the higher redshift sources (z>0.3) lie within the top right quadrant of the plots, when the Stern and Lacy AGN are identified we see the majority of these AGN also lie within this same quadrant. Looking at the AGN selected sources we see a slope close to unity at both MIR wavelengths, for 3.6µm the slope is m = 1.004 ± 0.155 and at 4.5µm it was found to be m = 0.980 ± 0.153. I conclude the thesis by summarizing the work and discussing future work to be undertaken as a result of the research
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
- …
