1,721,314 research outputs found
Modification of Fano resonances by resonant polaron coupling in bulk GaAs.
No full textStrong modifications of the magneto-excitonic Fano lineshapes have been observed in the photoluminescence-excitation spectra of bulk GaAs when the energies of the transitions are tuned by an external magnetic field. We identify the origin of these changes as resonant polaronic coupling between the electrons or holes, forming the excitons, with longitudinal-optical phonons, in conduction and valence bands respectively. The resonant polaron effect alters the magneto-excitonic discrete states, destroying the quantum interferences responsible for the Fano asymmetry
Quenching of Fano resonances due to electron-phonon polaronic interaction
No full textWe have observed distinct Fano resonances in the pseudo-absorption spectra of GaAs in an external magnetic field. The polaronic interaction quenches the resonances whenever the energies of the electrons (holes) of a magneto-exciton are tuned, by the magnetic field, to one longitudinal-optical phonon above the fundamental Landau level in the conduction- (valence-) band. A line shape analysis of the resonances yields a singular behavior of the parameters characterizing the Fano profiles
LINEAR AND NONLINEAR OPTICAL PROPERTIES OF AlGaAs/AlAs MULTIPLE-QUANTUM-WELLS AT ROOM TEMPERATURE
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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
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
Evolution of Fano resonances in two- and three dimensional semiconductors with a magnetic fiel
No full textWe have studied the evolution of Fano resonances with an external magnetic field, applied in the Faraday configuration, in two- and three-dimensional semiconductors, by low-temperature photoluminescence excitation spectroscopy. The behavior of the spectra with increasing magnetic field strength depends strongly on the dimensionality of the system: Fano resonances emerge in 3D systems, while those lines which are asymmetric at zero field in 2D systems become more Lorentzian-like due to the suppression of interference paths
Modulation of Fano resonances by an external magnetic field in semiconductor quantum wells
No full textWe have studied the dimensionality dependence of the behavior of Fano resonances in the photoluminescence excitation spectra of GaAs---AlxGa1−xAs heterostructures in a magnetic field applied in the Faraday configuration. A striking difference is observed between quasi-two and quasi-three-dimensional systems: while the Fano profiles evolve into Lorentzian lineshapes in two-dimensional systems, Fano resonances emerge from the continuum in three-dimensional-systems with increasing magnetic field
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