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Charged Phonons. II. Second Quantization and Its Application to Galvanomagnetic Effect
Get PDFこの論文は国立情報学研究所の電子図書館事業により電子化されました
Charged Phonons III : Dispersion Relations in Metals
Get PDFこの論文は国立情報学研究所の電子図書館事業により電子化されました。連続媒質と見做された格子イオン系によって生ずるベクトルポテンシャルA及びスカラポテンシャルφに対して電子系が線型に応答する系を考える。弱磁場の場合はイオンのラーマ振動は電子によって遮蔽されphononとAlfven waveが生ずるが,磁場が高くなって,例えばそのエネルギー密度が電子数密度とFermiエネルギーとの積程度になると,イオンのラーマ振動は遮蔽されなくなりcharged phononが現われる。charged phononの伝播方向と磁場方向のなす角度をθとすると,右旋回分極ε=1に対しては(H^2_0/8π)|cosθ|>1/6n_0mv^2_0,左旋回分極ε=-1に対してはc^2q^2|cosθ|>Ω^2_pがその臨界条件となる。一方弱磁場に対して現われていたAlfven waveは前者の臨界値を境に,ε=±1に対してphononの寄与を凌駕し,更に強い磁場領域ではphononの効果は消失していく。従ってこの領域の磁場では当該モデルに於る格子イオンの効果は消失し,代ってほゞ電子-イオンガスの性質を現わすようになる。この臨界磁場はθ=0,横分極の音速=4.50×10^5cm/secのLi金属では,H_e～1.2MOeであり,例えば10MOeも印加すればAlfven waveの(位相速度)^2は(3.86×10^6)^2cm/secとなってphononの(音速)^2の73.6倍となる
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
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
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