1,720,988 research outputs found
Signatures Of Inhomogeneous Electronic State In Quantum Limit In Graphite
No full textIn-plane magnetoresistance (MR) measurements performed on highly oriented pyrolytic graphite (HOPG) in Corbino-disk geometry revealed signatures of the electronic inhomogeneous state. In particular, the obtained results showed that besides of the Shubnikov-de-Haas (SdH) effect, the magnetic field B > 4 T triggers MR oscillations of a different origin that are spatially asymmetric. The possible coexistence of different electronic states in quantized magnetic field is discussed. © 2009 World Scientific Publishing Company.23Dez/1327232726Iye, Y., (1982) Phys. Rev. B, 25, p. 5478(1984) Phys. Rev. B, 30, p. 7009Timp, G., Dresselhaus, P.D., Chieu, T.C., Dresselhaus, G., Iye, Y., (1983) Phys. Rev. B, 28, p. 7393Iye, Y., Dresselhaus, G., (1985) Phys. Rev. Lett, 54, p. 1182Fukuyama, H., Platzman, P.M., Anderson, P.W., (1979) Phys. Rev. B, 19, p. 5211Kopelevich, Y., Lemanov, V.V., Moehlecke, S., Torres, J.H.S., (1999) Phys. Solid State, 41, p. 1959Kopelevich, Y., Torres, J.H.S., da Silva, R.R., Mrowka, F., Kempa, H., Esquinazi, P., (2003) Phys. Rev. Lett, 90, p. 156402Tesanovic, Z., Rasolt, M., (1989) Phys. Rev. B, 39, p. 2718Akera, H., MacDonald, A.H., Girvin, S.M., Norman, M.R., (1991) Phys. Rev. Lett, 67, p. 2375Lukyanchuk and Y. Kopelevich, Phys. Rev. Lett. 93, 166402 (2004)Csathy, G.A., Tsui, D.C., Pfeiffer, L.N., West, K.W., (2004) Phys. Rev. Lett, 92, p. 25680
Ferromagnetic And Superconducting Instabilities In Graphite
No full textThis chapter outlines the ferromagnetic and superconducting instabilities in graphite. A structural disorder, topological defects, or adsorbed foreign atoms can be responsible for the occurrence of both ferromagnetic and superconducting patches in graphitic structures. It is suggested that the ferromagnetism in microporous carbon and nominal rh-C60 samples has a common origin, possibly associated with fullerene-like fragments. There exists both experimental and theoretical evidence that fullerene-like fragments, with positive and/or negative curvature, should be a common feature of microporous carbons. Such fragments should naturally appear in rh-C6o samples with partially destroyed C6o molecules. It is found that an adsorption followed by a desorption of oxygen gas at the graphite surface is responsible for the appearance and vanishing of the ferromagnetism, respectively. It is observed that as the applied field increases, the normal state orbital diamagnetism of graphite overcomes the paramagnetic contribution to the magnetization resulting in a negative total magnetization. The results indicate that the superconducting state is highly anisotropic and is associated with the graphite planes. © 2006 Elsevier B.V. All rights reserved.417436Kopelevich, Y., Lemanov, V.V., Moehlecke, S., Torres, J.H.S., (1999) Physics of the Solid State, 41, p. 1959Kopelevich, Y., Lemanov, V.V., Moehlecke, S., Torres, J.H.S., (1999) Fizika Tverd. Tela, 41, p. 2135Kopelevich, Y., Esquinazi, P., Torres, J.H.S., Moehlecke, S., (2000) J. Low Temp. Phys., 119, p. 691Kopelevich, Y., Esquinazi, P., Torres, H.S., da Silva, R.R., Kempa, H., Mrowka, F., Ocaña, R., (2003) Studies of High-Tc Superconductors, 45, p. 59. , Nova Sci Pub., N.Y. A.V. Narlikar (Ed.)Kopelevich, Y., Esquinazi, P., Torres, J.H.S., da Silva, R.R., Kempa, H., (2003) Advances in Solid State Physics, 43, p. 207Makarova, T.L., Sundqvist, B., Höhne, R., Esquinazi, P., Kopelevich, Y., Scharff, P., Davydov, V.A., Rakhmanina, A.V., (2001) Nature, 413, p. 716Wood, R.A., Lewis, M.H., Lees, M.R., Bennington, S.M., Cain, M.G., Kitamura, N., (2002) J. Phys.: Condens. Matter, 14, pp. L385Narozhnyi, V.N., Müller, K.-H., Eckert, D., Teresiak, A., Dunsch, L., Davydov, V.A., Kashevarova, L.S., Rakhmanina, A.V., (2003) Physica B, 329, p. 1217Coey, J.M.D., Venkatesan, M., Fitzgerald, C.B., Douvalis, A.P., Sanders, I.S., (2002) Nature, 420, p. 156Wang, X., Liu, Z.X., Zhang, Y.L., Li, F.Y., Lin, C.Q., (2002) J. Phys.: Condens. Matter., 14, p. 10265Kopelevich, Y., da Silva, R.R., Torres, J.H.S., Penicaud, A., Kyotani, T., (2003) Phys. Rev. B, 68, p. 092408da Silva, R.R., Torres, J.H.S., Kopelevich, Y., (2001) Phys. Rev. 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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
High-temperature Superconductivity In Graphite-sulfur Composites: Theoretical Analysis
No full textRecently superconductivity in graphite-sulfur composites was experimentally observed. In this work we have analyzed the electronic structure changes associated with the presence of sulfur atoms in one and two dimensional graphite layers. We have considered ordered and disordered sulfur atoms distributions in many configurations. The density of states (DOS) of these structures were obtained using the negative factor counting (NFC) technique coupled to a tight-binding Hamiltonian (Hückel type). Our results indicate that the incorporation of sulfur atoms at edge graphite layers (changing their global geometric curvature and increasing the DOS at the Fermi level) might be in the origin of the graphite superconductivity.689127132Da Silva, R.R., Tores, J.H.S., Kopelevich, Y., (2001) Phys. Rev. Lett., 87, pp. 147001-147011González, J., Guinea, F., Vozmediano, M.A.H., (2001) Phys. Rev. B, 63, p. 134421Nagamatsu, J., Nakagawa, N., Muranaka, T., Zenitani, Y., Akimitsu, J., (2001) Nature (London), 410, p. 63Dean, P., Martin, J.L., (1960) Proc. Roy. Soc., A259, p. 409Ladik, J., Seel, M., Otto, P., Bakhshi, A.K., (1986) Chem. Phys., 108, p. 203Galvão, D.S., Dos Santos, D.A., Laks, B., De Melo, C.P., Caldas, M.J., (1989) Phys. Rev. Lett., 63, p. 786Lavarda, F.C., Dos Santos, M.C., Galvão, D.S., Laks, B., (1994) Phys. Rev. Lett., 73, p. 1267Galvão, D.S., Laks, B., Da Silva, R.R., Torres, J.H.S., Kopelevich, Y., to be publishe
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
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