1,721,012 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
Magnetic petrology of the Ross Orogen in Oates Land (Antarctica)
No full textThis paper presents the results of a pilot study on the magnetic petrology of basement rock units
in the Ross Orogen in Oates Land (Antarctica). Magnetic susceptibilities of migmatitic gneisses – the
dominant lithology - are generally low (ilmenite+/-graphite-bearing rocks), with the exception of two
occurrences (magnetite+/-green spinel-bearing rocks) at Harald Bay and Burnside Ridge. Similar low values
are typical for most Granite Harbour Intrusives, except for the variably mylonitic Exiles Nunataks granite
and the Archangel Nunataks gabbros and pyroxenites, which are among the most magnetic rock types in the
area. Metamorphosed mafic and ultramafic rocks, occurring in outcrop as volumetrically minor bodies (lenses
of 1 dm to 10 m size), are variably but generally about one order of magnitude more highly magnetic than
country gneisses.
Petrological investigations on representative samples indicate that nearly pure or low-Ti magnetite is the only
ferrimagnetic phase, irrespective of lithologic type, and magnetic susceptibility values are always positively
correlated with the modal amount of magnetite. The rare occurrence of magnetite in the opaque mineralogy
of migmatitic gneisses indicates that appropriate chemical and fO2 conditions were only locally attained in
the region, and microstructural evidence indicate that magnetite possibly formed at different metamorphic
stages during the post–peak decompressional path at high T and/or the retrograde path. In variably magnetic
ultramafic and mafic lenses magnetite (almost pure to low-Ti) typically occurs as very fine grained opaque
inclusions in secondary hornblende and/or chlorite. This evidence indicates that a high proportion of
magnetite is of secondary origin and related to amphibolite grade or lower grade metamorphic processes.
Titanomagnetite and exolution features are documented in the gabbros from Archangel Nunataks, in which
the decrease of magnetite content is inversely correlated with the extent of sub-solidus late-magmatic reequilibration
(replacement of pyroxene by hornblende). Similar microstructural evidence of re-equilibration
during cooling was also found in the highly magnetic magnetite-bearing mylonitic hornblende-biotite granites
from Exiles Nunataks.
All highly magnetic rock units represent potential petrologic sources of regional crustal magnetic anomalies
in the Oates Land region as revealed by aeromagnetic surveys. In particular, the Exiles Nunataks magnetitebearing
granites are clearly marked by aeromagnetic anomalies forming a small part of the “Matusevich
Anomaly”, a prominent magnetic anomaly, co-linear with the Matusevich Glacier. The gabbros as exposed in
the southestermost Archangel Nunataks are correlated with a distinct high-amplitude anomaly that occurs at
this location and delineates the extent of the gabbroic intrusion itself. Significant volumes of metamorphosed
mafic/ultramafic rocks may account for the high-frequency anomaly chains flanking the main part of the
Matusevich Anomaly in the Lazarev Mountains
Gold-bearing veins in transcrustal fault zone in the Transantarctic Mountains (northern Victoria Land, Antarctica)
No full textVariations 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
Gold-bearing veins in northern Victoria Land, (Antarctica): structure, hydrothermal alteration and implications for the paleo-pacific margin of Gondwana
No full textAppropriate 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
Developing and testing multimedia educational tools to teach Polar Sciences in the Italian school
No full textHysteroscopic retrieval of occult IUD.
No full textThe direct view of the uterine cavity offered by hysteroscopy can provide valuable information about the position of an IUD, its condition, and its relationship with other formations, thereby facilitating its removal. The diagnostic and therapeutic reliability of this technique was analyzed in 8 women with occult IUDs. Involved were 3 Nova T IUDs, 2 Gravigards, 2 Minigravigards, and 1 Progestasert device. 1 patient had undergone unsuccessful curettage for removal of the IUD; none of the other women had experienced any surgical manipulation prior to the hysteroscopy. The surgery consisted of 4 steps: 1) distention of the uterine cavity by insufflation of carbon dioxide, 2) hysteroscopic location of the IUD, 3) sighted grasping of the IUD or IUD segment with forceps, and 4) removal of the device together with the hysteroscope under dynamic vision. Hysteroscopic location and removal were successful in all 8 patients, with no complications. Hysteroscopy is thus recommended as an alternative retrieval technique, especially in cases when it is necessary to assess the deterioration and possible myometrial penetration of the IUD or the inflammation of the uterine cavity
First finding of syntectonic gold mineralization in northern Victoria Land (Antarctica): a clue for the Paleo-Pacific margin of Gondwana
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