275,901 research outputs found
Growth of ultrathin twin-free b-oriented YBa2Cu3O7–x films
No full textTwin-free b-oriented YBa2Cu3O7–x films with a thickness less than 40 nm have been epitaxially grown on (100)SrLaGaO4 crystals. Based on the temperature dependence of resistance, the onset temperature of the transition to the superconducting state is found to be 90 K; the transition width is 4 K. The film growth has been performed in two stages. A (100)PrBa2Cu3O7 – x buffer layer was previously grown on a (100)SrLaGaO4 substrate by rf magnetron sputtering in an Ar–O2 gas mixture at a continuous and monotonic increase in temperature from 660 to 830°C. The main YBa2Cu3O7 – x film was grown on the buffer layer surface by pulsed laser deposition in an oxygen medium at a fixed temperature (800°C). The above processes were implemented in different chambers, which were connected by a vacuum channel for transporting samples. Both films were grown in situ, without contacting atmosphere in all growth stages. An X-ray diffraction study has shown that the YBa2Cu3O7 – x films are single-crystal and free of precipitates of other phases and domains of other orientations
Growth of twin-free b-oriented YBa2Cu3O7−x films
No full textYBa2Cu3O7−x films of b orientation have been grown on the surface of (100)SrLaGaO4 crystal. It is demonstrated that the films pass to the superconducting state at a temperature of 89 K. In the non superconducting region, the film resistance decreases linearly with a decrease in temperature at a rate of 30 Ω per 100°C. According to the X-ray diffraction data on the crystallographic structure of the YBa2Cu3O7−x films, they are single-crystal and b-oriented. It is shown that the films contain no domains of other crystallographic orientations, including a-oriented domains. Therefore, the films are free of structural twins
Temperature sensitivity and noise of Josephson detector on bicrystal sapphire substrates at 77 K
No full textCitation for the published paper: Tarasov, M. ; Stepantsov, E. ; Kalaboukhov, A. (2007) "Temperature sensitivity and noise of Josephson detector on bicrystal sapphire substrates at 77 K". JETP Letters, vol. 86(11), http://d
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Dispelling the Myths Behind First-author Citation Counts
No full textWe 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
Mining e-mail content for author identification forensics
No full textWe describe an investigation into e-mail content mining for author identification, or authorship attribution, for the purpose of forensic investigation. We focus our discussion on the ability to discriminate between authors for the case of both aggregated e-mail topics as well as across different email topics. An extended set of e-mail document features including structural characteristics and linguistic patterns were derived and, together with a Support Vector Machine learning algorithm, were used for mining the e-mail content. Experiments using a number of e-mail documents generated by different authors on a set of topics gave promising results for both aggregated and multi-topic author categorisation
Author Co-Citation Analysis (ACA): a powerful tool for representing implicit knowledge of scholar knowledge workers
No full textIn the last decade, knowledge has emerged as one of the most important and valuable organizational assets. Gradually this importance caused to emergence of new discipline entitled ―knowledge management‖. However one of the major challenges of knowledge management is conversion implicit or tacit knowledge to explicit knowledge. Thus Making knowledge visible so that it can be better accessed, discussed, valued or generally managed is a long-standing objective in knowledge management. Accordingly in this paper author co- citation analysis (ACA) will be proposed as an efficient technique of knowledge visualization in academia (Scholar knowledge workers)
Study of in-plane electrical transport anisotropy of a-axis oriented YBa2Cu3O7-δ nanodevices
No full textIn the present work, we report the growth of fully untwinned high-quality a-axis-oriented YBa2Cu3O7-δ films on (100) SrLaGaO4 substrates by using PrBa2Cu3O7-δ as a buffer layer. We also fabricated nanowires at different angles γ with respect to the [0,1,0] direction of the substrate and studied the in-plane anisotropy of the critical current density, which we explained by considering the anisotropy in the coherence length ξ and London penetration depth λL. Finally, half-integer Shapiro-like steps measured in slightly underdoped c-axis oriented (γ=90°) nanowires point towards a different transport regime, which could shed light on intriguing issues of high-critical-temperature superconductors
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