1,721,279 research outputs found
Size effect in waveguide coupled whispering gallery mode disk resonators
No full textWe investigate the bound and evanescent fields of the optical whispering gallery modes which are supported by a toroid microcavity and which may be used for a wide range of applications. Results of simulations using finite-difference time domain solutions of Maxwell's equations are compared with semi-analytical solutions based on coupled mode theory. Key parameters such as resonance frequencies, transmittance characteristics, coupling efficiencies, and bending/scattering losses are analyzed as a function of experimental variables such as size, distance, and fabrication roughness. Finally, the feasibility of single-atom detection is discussed
High-Q micro-resonators for trapping and detecting a single atom on a chip
No full textRecent progress in the manufacturing of high Q dielectric microresonant structures enables their use as photonic devices that can manipulate and/or detect single atoms on a nanometer scale. Of specific interest is the wafer-based manufacturing of resonators where a good control of the physical characteristics can be achieved during fabrication and during operation, while at the same time allowing integration with other functions on the chip. We also discuss experimental feasibility and compare with first experiments in the field
Single-atom detection using whispering gallery modes of microdisk resonators
No full textWe investigate the possibility of using dielectric microdisk resonators for the optical detection of single atoms trapped and cooled in magnetic microtraps near the surface of a substrate. The bound and evanescent fields of optical whispering-gallery modes are calculated and the coupling to straight waveguides is investigated using finite-difference time domain solutions of Maxwell's equations. Results are compared with semianalytical solutions based on coupled mode theory. We discuss atom detection efficiencies and the feasibility of nondestructive measurements in such a system depending on key parameters such as disk size, disk-waveguide coupling, and scattering losses
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
Possibility of single-atom detection on a chip
No full textWe investigate the optical detection of single atoms held in a microscopic atom trap close to a surface. Laser light is guided by optical fibers or optical microstructures via the atom to a photodetector. Our results suggest that with present-day technology microcavities can be built around the atom with sufficiently high finesse to permit unambiguous detection of a single atom in the trap with 10 µs of integration. We compare resonant and nonresonant detection schemes and discuss the requirements for detecting an atom without causing it to undergo spontaneous emission
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
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