1,720,993 research outputs found
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
Petrography and mineralogy of the C29/30 Candle Lake Kimberlite, Saskatchewan, Canada
Full text linkPetrography and mineralogy of the C29/30 Candle Lake kimberlite (Saskatchewan, Canada) was studied to understand the characteristics of the kimberlite. Using standard optical microscopy three units where distinguished; pyroclastic kimberlite; resedimented volcaniclastic kimberlite and a crystal tuff kimberlite unit. Each kimberlite unit has been classified based on textural relationships between magmaclasts and the interstitial matrix, as well as phenocrysts, macrocrysts and minor mineral phases within the magmaclasts ... The mineralogy of the C29/30 is typical of an archetype kimberlite. The minerals analyzed include spinels, serpentine, olivine, carbonates, phlogopite, perovskite, apatite, garnets, ilmenite and magnetite ... The eruption was shallow and excavated Mannville sandstones, Paleozoic limestone and any Colorado mudstone if present. The eruption style was probably dry-phreatomagmatic. This is supported by the shallow bowl shape of the kimberlite body with a depth to width ratio of 1:5
X-ray diffraction and Rietveld structural refinement of selected fluoroperovskites
Full text linkThis study presents an X-ray diffraction analysis and Rietveld structural
refinement of selected synthetic fluoroperovskite-type compounds including the Na1-xKxMgF3 solid solution series in addition to synthetic analogues of cryolite (Na2NaAlF6)
and simmonsite (Na2LiAlF6).
The Na1-xKxMgF3 solid solution series is comprised of three structurally distinct
perovskite phases. In order of increasing potassium they are; orthorhombic (Pbnm, a =
5.3609(1), b = 5.4862(1), c = 7.6661(1), Z = 4) in the x = 0 - 0.35 compositional range, tetragonal (P4/mbm, a = 5.444(3), c = 3.9217(3), Z = 2) in the x = 0.40 ~ 0.46
compositional range and cubic (see document
Accessory rare metal mineralization in the Coldwell Alkaline Complex, Northwest Ontario
Full text linkAccessory rare metal mineralization has been investigated in seven
lithologies in intrusive Centres I and III of the Coldwell alkaline complex. All
units contain minerals that are enriched in a suite of granitophlle elements,
which typically include Nb, REE, Y, Th, U and Zr. Mineral abundances,
composition, and mode of occurrence differ between units.
Centre III is characterized by crystallization of subhedral-to-euhedral
chevkinite, pyrochlore and monazite from late-stage melts or residual pore
fluids in the more-evolved quartz and ferro-edenite syenites. These minerals
are invariably altered to fluorocarbonate or recrystallized by later F‘ and
C032-bearing deuteric fluids. The Centre I, ferroaugite syenite minerals
exhibit similar morphological and replacement textures to those present in
Centre III. In contrast, the Craddock Cove syenite is mildly K and
Fe-metasomatised with incipient replacement of plagioclase and amphibole by
K-feldspar, zircon, fluorocarbonate, Nb-rutile (?), allanite, and rare chevkinite.
Fe-rich fluids under oxidizing conditions are believed to have precipitated
Fe3+ bearing fluorocarbonate in which one third of the (REE)F layers are
replaced by Fe3+ layers.
Most Centre I rare earth minerals are enriched in the HREE relative to those
from centre III, in particular pyrochlore, fluorocarbonate, allanite in the
eastern contact pegmatites and the quartz syenite dykes. Compositional data
for adjacent syntaxial intergrown domains of bastnaesite, synchysite, and
parisite indicate that HREE-enrichment may, in part, be influenced by the Ca
content of the species.
The highest contents of Ce (4193 ppm), Zr (1613 ppm), V (650 ppm), Th (223
ppm) and U (428 ppm) were found in the quartz syenite dykes intruding the
Craddock Cove syenite and Port Munroe megaxenolith. The emplacement of the
quartz syenite dykes and the introduction of the metasomatizing fluids of the
Craddock Cove syenite may be temporally related to the differentiation of
residual fluids in the apical zone of the Centre I magma chamber. Complexing
of F and CO32- with rare metals may have permitted their concentration,
transportation and precipitation in structurally favourable settings. The
megaxenoliths have been susceptible to brittle fracturing and should be
considered primary targets for further exploration. The Craddock Cove syenites,
although intruded by the dykes, may have been hot during dyke emplacement and
therefore not as prone to brittle fracturing
Petrology, geochemistry, sulphide and platinum-group element mineralization of the Geordie Lake intrusion, Coldwell Complex, Ontario
Full text linkPGE-bearing Geordie Lake intrusion is located in the north-central region of the Coldwell comples near the town of Marathon.The Geordie Lake Intrusion (GLI) consists of alternating zones of
layering-free troctolite and olivine gabbro outcropping in the north-central
part of the Coldwell alkaline complex, northwestern Ontario. The troctolite
exhibits harrisitic texture in which dendritic olivine (F044-56), plagioclase
(An48-57), and skeletal magnetite are the main constituents. Small amounts
of clinopyroxene (Di36Hd60Ae4-Di30Hd66Ae4) are present in the troctolite.
The ophitic olivine gabbro consists of clinopyroxene (Di4iHd54Ae5
Di29Hd66Ae5), plagioclase (An46-54), altered olivine, and skeletal
magnetite. Some gabbros contain high-alumina clinopyroxenes
(Ti-Px4CATS48Ae48-Ti-PxgCATS42Ae5o). Mineral chemistry and
whole-rock geochemistry indicate that the troctolite and gabbro are not
related by differentiation and their parent magma is a relatively evolved
low-alumina tholeiite. The GLI is characterized by high Sr, Rb, Ba, Th, Ta and
light rare-earth element (LREE) content but low in Ni and Cr content.
Europium anomalies are absent. Fe-Ti oxide geothermometry and
geobarometry of the troctolite and olivine gabbro give an average
equilibration temperature of 603° ± 35°C and oxygen fugacity of bar.
Disseminated chalcopyrite is the dominant style of Cu-sulphide
mineralization in the GLI. Massive chalcopyrite aggregates are rare
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