1,721,051 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
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
Variable Range Hopping in Metal Oxide Semiconductors: Low Temperature Transport Measurements on SnO2 and TiO2 Thin Films
Full text linkSpintronik ergänzt die konventionelle Halbleiterelektronik bereits an vielen Stellen der Informationstechnologie, die dadurch neben dem elektronischen Freiheitsgrad der Ladung auch den des Elektronenspins nutzen kann. Die klassische Trennung von elektronischer Datenverarbeitung und magnetischer Speicherung in der Informationstechnologie wurde mit der Entdeckung magnetoresistiver Effekte in magnetischen Schichtsystemen aufgehoben - an dieser Stelle treten die beiden Elektroneneigenschaften Spin und Ladung in Wechselwirkung.
Die enge Verknüpfung der magnetischen und elektrischen Eigenschaften erfordert ein genaues Verständnis der elektronischen Vorgänge in dotierten Metalloxid-Halbleitern, um Materialien wie die zwei Verbindungen SnO2 und TiO2 gezielter für spintronische Anforderungen zu modellieren. Zu diesem Zweck wurden Untersuchungen an diesen Materialien unternommen, um die grundlegenden Prozesse der Schichtherstellung, der Nachbehandlungen und die morphologische Charakterisierung bis zu deren Auswirkungen auf die elektrischen Transportmechanismen und die magnetische Phänomenologie zu studieren.
In der vorliegenden Arbeit werden die Herstellung von dünnen Zinndioxid- und Titandioxid-Schichten und die Resultate verschiedener physikalischer Charakterisierungsmethoden beschrieben. Die beiden Metalloxide wurden mit einem Sputterverfahren und mit einem thermischen Verdampfungsverfahren als dünne Schichten aufgebracht. Es wurden Mikroskop- und Röntgen-Beugungsuntersuchungen durchgeführt, um die Morphologie der Materialien zu untersuchen. Einige SnO2-Proben wurden einem Annealing unterzogen, die TiO2-Schichten wurden nachträglich mit Fe-Ionen dotiert. Die Untersuchungen konnten in einigen Fällen ferromagnetische Ordnung in TiO2:Fe mit Ordnungstemperaturen über 300 K bestätigen. Die Leitfähigkeitsmessungen der Schichten identifizieren den dominierenden Leitungsmechanismus als Variable Range Hopping zwischen lokalisierten Zuständen tief in der Bandlücke.Spintronics already increase the functionality of conventional semiconductor electronics, by utilizing the degree of freedom of the electrons charge and spin at the same time. The traditional separation of electronical data processing and magnetical data storage has been overturned by the discovery of magneto resistive effects in magnetic layer structures - at this point the spin and the charge of the electron interact.
To use compounds like SnO2 and TiO2 for spintronic devices a detailed understanding of the electronical processes in such materials is required. Mainly that is the close interconnection between magnetical and electronical properties in doped metal oxide semiconductors. For this purpose the fundamental processes of thin film deposition, the effects of secondary treatment and the morphological properties of these materials have been investigated, to study the influence on the electrical transport and the magnetical phenomenology.
In this work different deposition methods for tin dioxide und titanium dioxide thin films are described and the results of several physical characterizations are shown. Both compounds have been deposited as thin films with sputtering and with thermal evaporation. Investigations of the materials morphology were done by transmission electron and atomic force microscopy and X-Ray diffraction. Some SnO2 samples have been annealed, while the TiO2 thin films have been doped with Fe ions post-preparational. In some cases the results show ferromagnetical behaviour in TiO2:Fe with ordering temperatures above 300 K. The conductivity measurements identify the Variable Range Hopping of localized states in the band gap as the dominating electronic transport process
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Herstellung und Charakterisierung von dünnen Schichten aus MnSi, MnGe und Mn1-xFexSi: Magnetische Eigenschaften unter dem Einfluss von Verspannungen und Dünnschichteffekten
Full text linkIn magnetic materials without structural inversion symmetry the Dzyaloshinskii-Moriya interaction favours a perpendicular orientation of neighbored spins, which leads to a helical magnetic ground state. In an external magnetic field a variety of magnetic phases is realized, for example a skyrmion lattice in the A-phase close to the magnetic ordering temperature Tord. Skyrmions are topologically stable spin whirls offering, e.g., promising potential in the field of data storage. The compounds MnSi, MnGe and Mn1-xFexSi, which crystallize in the cubic B20 structure, belong to the most prominent examples of this materials' class. Thin films of the B20 compounds are of special interest, since anisotropies are induced by finite size effects and strain, which are able to stabilize the skyrmion phase in extended regions of the magnetic phase diagram. During this work MnSi thin films were grown by molecular beam epitaxy on Si(111) substrates. On the one hand samples were prepared by deposition of a Mn layer onto the substrate and subsequent annealing. This way Mn reacts with Si from the substrate to form MnSi. On the other hand films were grown by simultaneous deposition of Mn and Si. Susceptibility measurements reveal that Tord is thickness dependent for MnSi thin films. While films thicker than 10 nm possess an enhanced Tord of 43 K compared to the bulk value of 29 K, Tord decreases for thinner films. From this thickness dependence the spin-spin correlation length has been determined. The magnetic phase diagram of MnSi thin films was investigated by magnetization and magnetoresistivity measurements. The saturation field is enhanced compared to bulk MnSi and for applied magnetic fields below saturation further transitions into different magnetic phases occur. Moreover, resistivity measurements on MnSi thin films were performed under hydrostatic pressure, which can completely suppress magnetic order. At high pressure non-Fermi liquid behaviour could be identified by a T3/2 law of the resistivity at low temperatures. In the second part of this work MnGe and Mn1-xFexSi thin films were prepared on Si(111) substrates. While MnGe films posses a high magnetic ordering temperature of 200 K, magnetic order is suppressed for x = 0.15 +- 0.05 in Mn1-xFexSi thin films.In magnetischen Materialien, deren Struktur keine Inversionssymmetrie besitzt, begünstigt die Dzyaloshinskii-Moriya-Wechselwirkung eine senkrechte Ausrichtung benachbarter Spins, was zu einer helikalen magnetischen Struktur im Grundzustand führt. Durch ein externes Magnetfeld können verschiedene Phasen induziert werden, darunter ein Skyrmionengitter in der A-Phase direkt unterhalb der Ordnungstemperatur TOrd. Skyrmionen sind topologisch stabile Spinwirbel, die vielversprechende Anwendungsmöglichkeiten z. B. in der Datenspeicherung bieten. Die Verbindungen MnSi, MnGe and Mn1-xFexSi, die in der kubischen B20-Struktur kristallisieren, sind prominente Vertreter dieser Materialien. Dünne Filme der B20-Verbindungen sind von besonderem Interesse, da hier Anisotropien durch Verspannungen und Dünnschichteffekte hervorgerufen werden. Diese können die Skyrmionenphase in einem großen Bereich des magnetischen Phasendiagramms stabilisieren. In dieser Arbeit wurden dünne MnSi-Schichten mittels Molekularstrahlepitaxie auf Si(111) Substraten gewachsen. Einerseits wurden Filme hergestellt, indem eine Mn-Schicht auf dem Si-Substrat abgeschieden und anschließend einlegiert wurde, so dass das Mangan mit dem Silizium des Substrats zu MnSi reagiert. Andererseits wurden Filme durch gleichzeitiges Aufdampfen von Mn und Si gewachsen. In Suszeptibilitätsmessungen zeigte sich, dass TOrd für die MnSi-Filme eine Dickenabhängigkeit aufweist. Während sich die dickeren Filme durch ein gegenüber dem Volumenmaterial erhöhtes TOrd von 43 K auszeichnen, ist TOrd für die sehr dünnen Filme reduziert. Anhand der Dickenabhängigkeit von TOrd konnte die Spin-Spin-Korrelationslänge bestimmt werden. Das magnetische Phasendiagramm der dünnen MnSi-Filme wurde mittels Magnetisierungs- und Magnetowiderstandsmessungen untersucht. Dabei konnten im Vergleich zum Volumenmaterial erhöhte kritische Felder sowie weitere Übergänge in unterschiedliche magnetische Phasen beobachtet werden. Des Weiteren wurden Widerstandsmessungen an einer dünnen MnSi-Schicht unter hydrostatischem Druck durchgeführt. Diese zeigten, dass die magnetische Ordnung vollständig unterdrückt werden kann. Abweichungen vom Modell einer Fermi-Flüssigkeit wurden bei hohen Drücken durch ein T3/2-Verhalten des Widerstandes nachgewiesen. Im zweiten Teil der Arbeit wurden MnGe- und Mn1-xFexSi-Filme auf Si(111) hergestellt. Während die MnGe-Filme ein TOrd von 200 K besitzen, wird die Ordnung in Mn1-xFexSi-Filmen für x= 0,15 +- 0,05 unterdrückt
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