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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
Winter expedition to the Southwestern Kara Sea investigations on formation and transport of turbid sea-ice = Winter-Expedition in die südwestliche Kara-See
No full textFrühdiagenetische Mineralisationsprozesse und Mobilität der Spurenmetalle Cd, Pb und Cu im Porenwasser eines Elbwatt-Sediments (2. Teil: Laborarbeit)
No full textUnter Einsatz eines Vielkammer-Dialysebrettes wurde im Friihjahr 1990 ein Porenwasserprofil eines ungestörten Elbwatt-Sediments gewonnen. Die Porenwässer wurden mit Hilfe von polarographischen, voltammetrischen und einigen weiteren chemischen Methoden bezüglich der Mobilität und Bindungsformen von Spurenmetallen untersucht. Die Durchführung thermodynamischer Gleichgewichtsrechnungen ermöglichte eine Abschätzung von Mineralisations- und Lösungsprozessen im Sedimentkörper. Aufgrund der Beobachtung von Fällungsprodukten am Dialysebrett und infolge der durchgeführten Messungen konnte eine Horizont-Differenzierung des Sedimentkörpers in oxisches Milieu, wechselnd oxisch / postoxisches Milieu und permanent postoxisches Milieu vorgenommen werden. Diese Milieu-Einteilung wurde durch die thermodynamischen Gleichgewichtsrechnungen bestätigt. Besonderes Augenmerk wurde auf die Bindungsformen und Mineralisationsprozesse im postoxischen Sedimentmilieu gerichtet. Das oxische Milieu beschränkt sich in den Sedimenten des Heuckenlocks auf den oberen cm. Indikatoren hierfür waren eine stark vermehrte Freisetzung der Spurenmetalle Cadmium, Kupfer und auch Blei aus der mineralisierten organischen Substanz sowie das Fehlen von Fe(II) im Porenwasser und die Ausbildung besonders kräftiger Oxidhydratkrusten am Dialysebrett. Die Spurenmetall-Konzentrationen werden in der oxischen Zone also durch die Freisetzung aus der organischen Substanz und die Adsorption an den frisch gebildeten Oxidhydraten kontrolliert. Das periodisch oxisch / postoxische Milieu ist während der sauerstoffbeeinflußten Phasen von starker Oxidhydratbildung gekennzeichnet. Diese werden unter anaeroben Bedingungen nicht vollständig wieder gelöst. Die Spurenmetall-Konzentrationen liegen unter denen der oxischen Zone. Die Kontrolle der Konzentration erfolgt über die Adsorption der Metalle (Cd, Cu) an den Oxidhydraten und die Bildung inerter Komplexe. Ebenso kann die Fällung von Metallsulfiden eine Rolle spielen. Die Sulfidgehalte liegen jedoch unter der Bestimmungsgrenze von ca. 100 nM und konnten trotz des Einsatzes sehr empfindlicher polarographischer Meßmethoden nicht detektiert werden. Die wechselnd oxisch / postoxische Schicht (und auch die oxische Schicht) sind an Fe-Sulfid und Eisenphosphat deutlich untersättigt. Gleiches gilt für Mangansulfid und -phosphat. Dies beruht auf der Oxidation des Sulfids und der Adsorption des Phosphat-Anions an den Oxidhydraten. Im permanent postoxischen Milieu zeigen die thermodynamischen Gleichgewichtsrechnungen, daß die Konzentrationen der Spurenmetalle über die Bildung von Metallsulfiden kontrolliert werden. Schon bei Sulfidkonzentrationen von 100 nM kommt es zur massiven Bildung von sulfidischen Mineralen. Die von WALLMANN (1990) in Suspensionsversuchen gemachte Beobachtung, daß im postoxischen Milieu bereits eine Fällung von Sulfidmineralen bei Sulfidkonzentrationen unter 1 μM (BERNER 1981) stattfindet, konnte erstmals in einem Geländeversuch verifiziert werden. Es gelang zusätzlich, die Bestimmungsgrenze für Sulfid in natürlichen Porenwässern mit Hilfe polarographischer Meßmethoden auf 0.1 μM zu senken. Die Konzentrationen der Spurenmetalle in der Lösung waren etwa vergleichbar mit denen der wechselnd oxisch / postoxischen Schicht. Die starke Übersättigung in den unteren Profilbereichen zeigt an, daß neben dem (steigenden) Sulfidgehalt vor allem inerte organische Komplexe und Kolloide die Spurenmetall-Konzentrationen in der Lösung kontrollieren. Die permanent postoxische Zone ist ebenfalls durch Sättigung an Eisenphosphat gekennzeichnet. Übersättigung gilt für das gesamte Profil an Eisen- und Mangankarbonat; die Bildung dieser Minerale ist offensichtlich kinetisch gehemmt. Ein weiterer Ansatz dieser Arbeit bestand darin, das Meßverfahren und die Meßparameter an der rotierenden Quecksilberfilmelektrode für Spurenmetall-Bestimmungen im unteren ppt-Bereich (ng/l) zu modifizieren. Die Rotel-Elektrode erwies sich als sehr leistungsfähig; so konnten die Bestimmunggrenzen für Cadmium und Blei unter den gegebenen Laborbedingungen auf 5-15 ppt gesenkt werden. Im Zuge der Messungen zeigten sich jedoch Metall-Konzentrationen in den Porenlösungen, die einen weiteren Einsatz der rotierenden Quecksilberfilmelektrode nicht ratsam erscheinen ließen. Dennoch ist der Einsatz dieser Methode bei entsprechender Einarbeitung des Benutzers und Qualität der Meßapparaturen als probates Meßverfahren in der Spurenanalytik zu betrachten
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
Die Laptevsee - eine Schlüsselregion für den Fremdstoffeintrag in das arktische Meereis
No full textLarge areas of the inner Siberian Laptev Sea are covered during winter (October to May) by a coastal fast ice canopy. Due to offshore winds the edge of fast ice is bordered by an as much as 2000 km long and 30 km wide zone of open water (flaw lead). The maintainance and width of the flaw lead and the dynamics of the adjacent dritt ice cover depend significantly on regional and local wind regimes. The Laptev Sea flaw lead heat fluxes and ice production rates were estimated by onedimensional energy balance calculations for the 1991/92 winter season. Based on the division of the flaw lead into 14 sub-sections, regional initial new ice formation over open water was estimated considering meteorological and oceanographic parameters. Accordingly, western, southern and northeastern flaw lead sections are characterized by highest new ice production rates. These lead sections are maintained for as long as 3 or 4 weeks due to regional offshore winds. The total amount of new ice (approx. 250 km3) produced in the Laptev Sea flaw lead during 1991/92 cold season contributes only 2.5 % to the volume of pack formed in the entire Central Arctic Ocean in the same period. Hence, while the Laptev Sea flaw lead produces considerable amounts of new ice on local scales, however, it does not play the part of the most "significant sea ice factory" for the entire Arctic Ocean. The Laptev Sea ice-rafted material reveals clear sedimentological similarities to local shelf surface deposits. Especially the silt fraction of both environments shows considerable conformity in respect to total fraction percentages, high quartz/feldspar contents, percentages of sub-fractions and the degree of roundness. The clay fraction of both sample groups reveals significant similarities in respect to mineral assembiages, such as smectite and illite content, as well. Diverging sedimentological parameters are documented in snow sediments and suspended particulate matter, respectively. Hence, in particular eolian contribution to sea ice sediments is of minor importance. The similar sedimentological characteristics of shelf bottom and sea ice sediments in the Laptev Sea point to turbulent hydrodynamic processes, which resuspend bottom material, litt it up to the water surface and incorporate the sediment into the newly formed ice. Langmuir circulation, thermohaline convection and wave action can serve as possible motors for the entrainment mechanisms such as suspension freezing, near surface slush-ice filtration and anchor ice formation. Nearly identical patterns of Polychlorinated Biphenyls (PCS) in Laptev Sea ice- and shelf-surface sediments support the assumption of bottom sediment entrainment into locally formed ice steered by hydrodynamic processes. On the basis of averaged sediment concentrations in the ice produced in the entire flaw lead and assuming that the turbid new ice from this area is advected to the Central Arctic Basin, the sediment expert can be estimated to amount 10 Mill. t during one winter season. Released in the Norwegian-Greenland Sea, this material can contribute roughly 28 % to the annual deep-sea
sediment accumulation rate in that area. Another 11 Mill. t of sediment, incorporated in the Laptev Sea fast-ice cover, can be locally released, re-distributed and re-deposited during the melt season. Using smectite in sea ice sediments as a mineralogical tracer, the general division of the Transpolar Drift into Siberian and Polar Branch, respectively, can be confirmed. Accordingly, smectiterich sediments in the Siberian Branch originate from the Laptev Sea or the eastern Kara Sea, whereas smectite-poor materials in the Polar Branch probably are derived from easterly shelf regions such as East Siberian or Chukchi Seas
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
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