1,721,003 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
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
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
Geometallurgical Evaluation of the Nkout (Cameroon) and Putu (Liberia) Iron Ore Deposits
No full textThe Nkout (Cameroon) and Putu (Liberia) oxide facies iron ore deposits comprise fresh magnetite banded iron formation (BIF) at depth, which weathers towards the surface, forming high grade martite–goethite ores. This study aimed to improve the mineralogical understanding of these deposits in order to predict their metallurgical responses. It concentrated on developing the QEMSCAN® technique and testing its application to these ore types, but also used a variety of other analysis methods. The QEMSCAN® species identification protocol was developed to include three goethite entries: goethite/limonite, phosphorus-bearing and aluminium-bearing goethite. QEMSCAN® was also used to distinguish between the iron oxides using their backscattered electron signals. To test the correlation between the mineralogy and metallurgical characteristics, magnetic separations were carried out.
The samples were divided into 4 main groups based on their whole rock Fe content, determined by XRF analysis, and their degree of weathering: enriched material, weathered magnetite itabirite, transitional magnetite itabirite and magnetite itabirite. Quartz and Al oxide and hydroxide minerals such as gibbsite are the major gangue minerals in the magnetite BIF and martite–goethite ores respectively. From the QEMSCAN® analysis it was concluded that the iron oxides are closely associated and liberation of them individually is poor. Liberation increases when they are grouped together as iron oxide. Chamosite concentrations > 6 wt. % significantly lower liberation of the iron oxides. From the metallurgical testing, it was concluded that iron oxide modal mineralogy gives an indication of iron recovery but other QEMSCAN® data such as mineral association and liberation could be important especially if the iron oxide minerals are not liberated. Grain size and instrument characteristics also affect recovery of iron minerals.
There is no evidence to show that there is any structural control on the BIF mineralisation at Nkout because metamorphism has significantly affected the lithological characteristics. The BIF mineralised zones occur as stacks with no particular stratigraphic relationship. Alteration and stratigraphy are the main controls on the martite–goethite ores. These results are applicable to most other BIFs so that as direct shipping ores are exhausted, the approach used here can help to develop the lower grade portions of the deposits.Association of Commonwealth Universitie
The Geological Controls on the Heavy Rare Earth Element Enriched Alteration Zone of Area 4, Lofdal, Khorixas, Namibia
No full textThe “heavy” rare earths (HREEs) are the most critical of all REEs, and are attracting much market and exploration attention today since China imposed export quotas in 2011.
The Lofdal Intrusive Complex, Khorixas, Namibia is enriched with heavy rare earth (HREE) mineralisation within the late hydrothermal zones associated with carbonatites, proximate to the complex’s syenite intrusions, and are generally controlled by older basement structures. One of these enriched HREE alteration zones is “Area 4”, now a proven CIM NI 43-101 compliant indicated and inferred resource, and sits at the top for REE basket price in the TMR world index of REE projects.
Brecciated fenite zones are repeatedly overprinted, commonly hosting greater HREE mineralisation amongst the “busiest” overprints. The fenitisation and brecciation providing the ground preparation for REE deposition in Area 4 have similarities to the Kangankunde and Chilwa carbonatite complexes in Malawi, where HREE enrichment can be found in proximal brecciated fenite zones.
90% of the HREE deportment in Area 4 is in the mineral xenotime, and is commonly associated with rutile (+/-Nb), apatite, zircon, aeschynite, synchysite, and thorite. Variations of this assemblage reside in carbonate phases (calcite, dolomite, ankerite), albite, phlogopite-biotite, and magnetite/hematite.
This study enhances the characterisation of the HREE mineral resource in Area 4 by combining details of drill core textural features, whole-rock major to trace element data analysis (ICP-MS) through the alteration zone and HREE mineralisation, with petrological and geochemical analysis of the major HREE bearing phases. 41 samples, representing a range of xenotime mineralised intercepts, of have been analysed petrologically via microscopy, cathodoluminescence and SEM/EDS; and geochemically via EPMA.
The variability, fractionation, and partitioning between the REE in the Area 4 xenotimes is compared to synthetic analogues, and to other xenotimes of the Lofdal Complex outside of Area 4, and compared to xenotimes from Witwatersrand, South Africa, and from Browns Range, Australia.
REE budget in xenotime can vary in proportion, as well as other element substitution and replacement into either the Y-site (A), or PO4 site (T). Substitutions into the xenotime lattice importantly include Th and U. Tested here is whether variations in ionic radii between the REE in xenotime can provide valuable clues to formational environment, and help to delineate differentiation in paragenses. Gd is in a unique position as it marks the change from unpaired to paired electrons in the filling stages of 4f orbitals, and Gd is shared between the second and the third tetrad. How the GdPO4 polymorph relates across the miscibility gap between LREE phosphate (monazite) and HREE (xenotime) in the Area 4 xenotimes appears temperature dependent. Experimental studies here have shown that in greater overprinted sections modifying fluids effectively “steal” Gd from xenotime to be lost to the fluid, and to LREE phases such as synchysite. Any xenotime that re-crystallises from these lower temperature fluids has been shown to have a higher HREE content, lower Th, but smaller grain size. Corrosion and re-precipitation of xenotime leads to Th being expelled from hydrothermal fluid leading Th to form its own phase, i.e. the silicate thorite, albeit proximal to xenotime, but importantly not substituting into the xenotime lattice, and that this is also shown to be temperature dependent.
Textural and compositional data indicate hydrothermal modification of earlier REE bearing phases. Suggested REE transporting ligands in carbo-hydrothermal fluids to later modifying hydrothermal fluids are perhaps a combination, and evolution through, HCO3, PO4 and HS, for example at >300°C, to Cl complexing ligands at to lower temperature <300°C . Decompression as a result of pregnant solution migrating into open space in fractures, fluid/rock interaction with albite, and especially dolomite, have been shown to be effective factors in depositing xenotime from solution.
The different stages of hydrothermal activity have been shown to have implications on the chemical and physical structure of the xenotime. This variability has economic implications when it comes to targeting ore, and to mineral processing
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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