1,720,967 research outputs found
Theory of Refraction, Ray-Wave Tilt, Hidden Momentum, and Apparent Topological Phases in Isotropy-Broken Materials based on Electromagnetism of Moving Media
Get PDFOne of the problems of physics arguably greater in stature than even mathematical Hilberts problems is the mysterious nature of electromagnetic momentum in materials. In this paper we show that the difference between the Minkowski and Abraham momenta, which is composed of the Roentgen and Shockley hidden momenta, is directly related to the phenomenon of refraction and the tilt of rays from the wavefront propagation direction. We demonstrate that individual electromagnetic waves with non-unit indices of refraction n appear as quasistatic high-k waves to an observer in the proper frames of the waves. When Lorentz transformed into the material rest frames these high-k waves are Fresnel-Fizeau dragged from rest to their phase velocities and acquire longitudinal hidden momentum and related refractive properties. On the material level all electromagnetic waves belong to Fresnel wave surfaces topologically classified according to hyperbolic phases by Durach and determined from the electromagnetic material parameters. To moving observers, material parameters appear modified, which leads not only to the alterations of Fresnel wave surfaces, but even the topological classes of the materials may appear differently in moving frames. We discuss the phenomenon of the electromagnetic momentum tilt, defined as non-zero angle between Abraham and Minkowski momenta or equivalently between the rays and the wavefront propagation direction. We show that momentum tilt is only possible in isotropy-broken media, where E and H fields can be longitudinally polarized in presence of electric and magnetic bound charge waves. The momentum tilt can be understood as differential aberration of rays and waves when observed in material rest frame.21 pages, 6 figure
Giant Plasmonic Energy and Momentum Transfer on the Nanoscale
Get PDFWe have developed a general theory of the plasmonic enhancement of many-body phenomena resulting in a closed expression for the surface plasmon-dressed Coulomb interaction. It is shown that this interaction has a resonant nature. We have also demonstrated that renormalized interaction is a long-ranged interaction whose intensity is considerably increased compared to bare Coulomb interaction over the entire region near the plasmonic nanostructure. We illustrate this theory by re-deriving the mirror charge potential near a metal sphere as well as the quasistatic potential behind the so-called perfect lens at the surface plasmon (SP) frequency. The dressed interaction for an important example of a metal–dielectric nanoshell is also explicitly calculated and analyzed. The renormalization and plasmonic enhancement of the Coulomb interaction is a universal effect, which affects a wide range of many-body phenomena in the vicinity of metal nanostructures: chemical reactions, scattering between charge carriers, exciton formation, Auger recombination, carrier multiplication, etc. We have described the nanoplasmonic-enhanced Förster resonant energy transfer (FRET) between quantum dots near a metal nanoshell. It is shown that this process is very efficient near high-aspect-ratio nanoshells. We have also obtained a general expression for the force exerted by an electromagnetic field on an extended polarizable object. This expression is applicable to a wide range of situations important for nanotechnology. Most importantly, this result is of fundamental importance for processes involving interaction of nanoplasmonic fields with metal electrons. Using the obtained expression for the force, we have described a giant surface-plasmoninduced drag-effect rectification (SPIDER), which exists under conditions of the extreme nanoplasmonic confinement. Under realistic conditions in nanowires, this giant SPIDER generates rectified THz potential differences up to 10 V and extremely strong electric fields up to 10^5-10^6 V/cm. It can serve as a powerful nanoscale source of THz radiation. The giant SPIDER opens up a new field of ultraintense THz nanooptics with wide potential applications in nanotechnology and nanoscience, including microelectronics, nanoplasmonics, and biomedicine. Additionally, the SPIDER is an ultrafast effect whose bandwidth for nanometric wires is 20 THz, which allows for detection of femtosecond pulses on the nanoscale
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
On the Nature of Plasmon Drag Effect
No full textLight-matter momentum transfer in plasmonic materials is theoretically discussed in the framework of a plasmonic pressure mechanism taking into account nonequilibrium electron dynamics and the thermalization process. We show that our approach explains the experimentally observed relationship between the plasmon-related electromotive force and the absorption and allows one to correctly predict the magnitude of the plasmon drag electromotive force in flat metal films. We extend our theory to metal films with modulated profiles and show that the simple relationship between plasmonic energy and momentum transfer holds at relatively small amplitudes of height modulation and an approximation of laminar electron drift. The theoretical groundwork is laid for further investigations of shape-controlled plasmon drag in nanostructured metal
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